Untitled - Latin American Journal of Aquatic Research
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Untitled - Latin American Journal of Aquatic Research
Latin American Journal of Aquatic Research www.lajar.cl ISSN 0718 -560X www.scielo.cl CHIEF EDITOR Sergio Palma Pontificia Universidad Católica de Valparaíso, Chile [email protected] ASSOCIATE EDITORS Cristian Aldea Universidad de Magallanes, Chile Álvaro J. Almeida Bicudo Universidad Federal Rural de Permambuco, Brasil José Angel Alvarez Perez Universidade do Vale do Itajaí, Brasil Patricio Arana Pontifícia Universidad Católica de Valparaíso, Chile Eduardo Ballester Universidade Federal do Paraná, Brasil Sandra Bravo Universidad Austral de Chile, Chile Claudia S. Bremec Instituto de Investigación y Desarrollo Pesquero, Argentina Enrique A. Crespo Centro Nacional Patagónico, Argentina Patricio Dantagnan Universidad Católica de Temuco, Chile Enrique Dupré Universidad Católica del Norte, Chile Diego Giberto Instituto de Investigación y Desarrollo Pesquero, Argentina Maurício Laterça-Martins Universidade Federal de Santa Catarina, Brasil César Lodeiros-Seijo Instituto Oceanográfico de Venezuela Universidad de Oriente, Venezuela Beatriz E. Modenutti Universidad Nacional del Comahue Argentina Luis M. Pardo Universidad Austral de Chile, Chile Guido Plaza Pontificia Universidad Católica de Valparaíso, Chile Jesús T. Ponce Universidad Autónoma de Nayarit, México Ricardo Prego Instituto de Investigaciones Marinas, España Erich Rudolph Universidad de Los Lagos, Chile Nelson Silva Pontificia Universidad Católica de Valparaíso, Chile Oscar Sosa-Nishizaki Centro de Investigación Científica y Educación Superior de Ensenada, México Ingo Wehrtmann Universidad de Costa Rica Costa Rica Financiamiento parcial de CONICYT obtenido en el Concurso “Fondo de Publicación de Revistas Científicas año 2015” Escuela de Ciencias del Mar, Pontificia Universidad Católica de Valparaíso Casilla 1020, Valparaíso, Chile, Fax: 56-32-2274206, E-mail: [email protected] INVITED REVIEWERS IN REGULAR ISSUES OF VOLUME 43 (2015) Alejandro Abarca Universidad Tecnológica de Chile Coquimbo, Chile Isabel Abdo Centro de Investigación en Alimentos y Desarrollo Sonora, México Bernabé Aguilar Universidad de Guadalajara, Guadalajara, México Gabriel Aguirre Universidad Autónoma de Tamaulipas, Tamaulipas, México Gabriela Aguirre Universidad de Cádiz, Cádiz, España Jorge Alfaro Universidad Nacional, Heredia, Costa Rica Carlos Alvarez Universidad Autónoma Metropolitana, Iztapalapa, México Luis Alvarez Grupo Piscimar, La Habana, Cuba Píndaro Alvaréz Instituto Politécnico Nacional, Sinaloa, México Gustavo Arencibia Centro de Investigaciones Pesqueras, La Habana, Cuba Lenin Arias Rodríguez Universidad Juárez Autónoma de Tabasco, Tabasco, México Iván Arismendi Oregon State University, Oregon, United State of America Eddie Aristizabal Instituto Nacional de Investigación y Desarrollo Pesquero Mar del Plata, Argentina Antônio Ávila Centro APTA, Instituto de Pesca Santos, Brasil Julia Azanza Instituto Superior de Tecnologías y Ciencias Aplicadas La Habana, Cuba Pedro Báez Museo Nacional de Historia Natural Santiago, Chile Christine Band Instituto Politécnico Nacional, Ciudad de México México Benjamín Barón Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, México Roberto Bastias Pontificia Universidad Católica de Valparaíso Valparaíso, Chile Marcela Bastidas Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina Raymond Bauer University of Louisiana, Louisiana, Estados Unidos Mauro Belleggia Instituto Nacional de Investigación y Desarrollo Pesquero Mar del Plata, Argentina Victoria Besada Instituto Español de Oceanografía, Madrid, España Álvaro Bicudo Universidad Federal Rural de Pernambuco, Garanhuns, Brazil Ramon Bonfil Universidade Federal Rural, Recife, Brasil Sandra Bravo Universidad Austral de Chile, Puerto Montt, Chile Odalisca Breedy Universidad de Costa Rica, San José, Costa Rica Alejandro Buschmann Universidad de los Lagos, Puerto Montt, Chile José Caballero Centro de Investigación Científica de Yucatán Yucatán, México Ariel Cabreira Instituto Nacional de Investigación y Desarrollo Pesquero Buenos Aires, Argentina Marco Cadena Universidad Autónoma de Baja California Sur, México Danilo Calliari Universidad de la República, Montevideo, Uruguay Antonio Camacho Universidad de Valencia, Valencia, España Bernardita Campos Universidad de Valparaíso, Valparaíso, Chile Jaime Cantera Universidad del Valle, Cali, Colombia Nicolás Castañeda Universidad Autónoma de Sinaloa, Sinaloa, México Leonardo Castro Universidad de Concepción, Concepción, Chile Rosario Cisneros Instituto del Mar del Perú, Callao, Perú Mauricio Coelho Universidade do Estado de Santa Catarina, Santa Catarina, Brasil Gabriel Claramunt Universidad Arturo Prat, Iquique, Chile Wilfrido Contreras Universidad Juárez Autónoma de Tabasco Tabasco, México Bruno Correa Centro de Información de Recursos Ambientales Santa Catarina, Brazil Marco Correa Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile Alessandra Cristina Universidade Federal do Ceará, Fortaleza, Brasil José Cuesta Consejo Superior de Investigaciones Científicas Cádiz, España Natalia da Costa Marchiori Empresa Pesquisa Agropecuária Extensão Rural de Santa Catarina, Itajaí, Brasil Lilian da Silva Universidade Federal do Paraná, Paraná, Brasil Patricia da Silva Universidade Federal da Paraíba, Paraíba, Chile Patricio Dantagnan Universidad Católica de Temuco, Temuco, Chile Marcos De Donato Universidad de Oriente, Cumaná, Venezuela Patricio De Los Ríos Universidad Católica de Temuco, Temuco, Chile Luisa Delgado Universidad de Chile, Santiago, Chile Juan Díaz Pontificia Universidad Católica de Valparaíso Valparaíso, Chile Verónica Diaz Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina Mariano Diez Centro Austral de Investigaciones Científicas, Ushuaia, Argentina Magda Domínguez Instituto Nacional de Pesca, Ciudad de México, México Fernanda Duarte Universidade Federal de Pernambuco, Pernambuco, Brasil Rodolfo Elias Universidad Nacional de Mar del Plata, Buenos Aires, Argentina Ileana Espejel Universidad Autónoma de Baja California, Ensenada, México Michael Frick Caretta Research Project, Georgia, United State of America Mario Galaviz Universidad Autónoma de Baja California Baja California, México José Gallardo Pontificia Universidad Católica de Valparaíso Valparaíso, Chile Ricardo Galleguillos Universidad de Concepción, Concepción, Chile Felipe Galván Centro Interdisciplinario de Ciencias Marinas, La Paz, México Jonatan Gardner Victoria University of Wellington, Wellington, New Zealand Manuel García Universidad Autónoma de Guadalajara, Guadalajara, México Rebeca Gasca El Colegio de la Frontera Sur, Villahermosa, México Gabriel Genzano Universidad Nacional de Mar del Plata, Mar del Plata, Argentina Juliana Giménez Universidad de Buenos Aires, Buenos Aires, Argentina Ligia Gonçalves Instituto Nacional de Pesquisas da Amazônia, Manaus, Brasil Paola González Universidad Católica de la Santísima Concepción Concepción, Chile Alejandro Guerra Centro de Investigaciones Marinas, Vigo, España Sandra M. Guerrero Universidad Nacional Autónoma de México Ciudad de México, México María Fernández Universidad Nacional de Río Cuarto, Córdoba, Argentina Manuel Haimovici Universidade Federal do Rio Grande, Rio Grande, Brasil Cesar Hernández Universidad Autónoma de Tamaulipas, Victoria Tamaulipas, México Daniel Hernández Universidad Autónoma del Estado de Morelos, Morelos, México María Hernández Universidad Juárez Autónoma de Tabasco, Tabasco, México Martha Hernández Instituto Tecnológico de Boca del Río, Veracruz, México Milton Hernández Instituto Tecnológico de Mazatlán, Mazatlán, México Monica Hoffmeyer Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina Margaret Hunter Southeast Ecological Science, Gainesville, United State José Iannacone Universidad Nacional Federico Villarreal, Lima, Perú Carlos Jara Universidad Austral de Chile, Valdivia, Chile Shaleyla Kelez Centro para la Conservación Integral de los Ecosistemas Marinos del Pacífico del Este, San Borja, Perú Maurício Laterça Universidade Federal de Santa Catarina, Florianópolis, Brasil Javier Legua Instituto de Fomento Pesquero, Valparaíso, Chile Mairin Lemus Universidad de Oriente, Sucre, Venezuela Carlos Lezama Universidad de Colima, Colima, México Alejandra Llanos-Rivera Universidad de Concepción, Concepción, Chile Karin Lohrmann Universidad Católica del Norte, Coquimbo, Chile Luis Lopes Universidad de São Paulo, Sao Paulo, Brasil Daniel López Universidad de Playa Ancha, Valparaíso, Chile Inmaculada López La Universidad de Granada, Granada, España Laura López Universidad de Buenos Aires, Buenos Aires, Argentina Luis López Instituto Español de Oceanografía, Islas Canarias, España Sebastián López Universidad Andres Bello, Santiago, Chile Christopher Lowe California State University Long Beach, California United State of America Antonio Luna Instituto Politécnico Nacional, Sinaloa, México Cristiana Maciel Universidade Federal do Pará, Pará, Brasil Lidia Mansur Pontificia Universidad Católica de Chile, Santiago, Chile Alfonso Mardones Universidad Católica de Temuco, Temuco, Chile Luis Martínez Universidad de Sonora, Sonora, México Marcel Martínez Centro de Investigación en Alimentación y Desarrollo, Sonora, México Silvio Maurano Universidade de Recife, Recife, Brasil Ricardo Medina Universidad Central de Las Villas, Santa Clara, Cuba Paola Mejía Fundación SQUALUS, Cali, Colombia Anselmo Miranda Universidad Estatal de Sonora, Sonora, México Vivian Montecinos Universidad de Chile, Santiago, Chile Cassiano Monteiro Universidade Federal Fluminense, Niterói, Brasil Américo Montiel Universidad de Magallanes, Punta Arenas, Chile Erika Montoya Instituto de Investigaciones Marinas y Costeras, Santa Marta Colombia María Cristina Morales Universidad Católica del Norte, Coquimbo, Chile María Monroy Universidad Nacional Autónoma de México, Ciudad de México México Francisco Moyano Universidad de Almería, Almería, España Pablo Muniz Universidad de la República, Montevideo, Uruguay Jorge Navarro Universidad Austral de Chile, Valdivia, Chile Marcelo Oliva Universidad de Antofagasta, Antofagasta, Chile Alfreldo Olivera Universidad Rural Federal de Pernambuco, Recife, Brasil Mauricio Ortiz International Commission for the Conservation of Atlantic Tunas Madrid, España Natalia Ospina Universidad de Varsovia, Varsovia, Polonia Yannis Papastamatiou University of St Andrews, Scotland, United Kingdom Jorge Paramo Universidad de Magdalena, Santa Marta, Colombia Germán Pequeño Universidad Austral de Chile, Valdivia, Chile Alitiene Pereira Empresa Brasileira de Pesquisa Agropecuária, Brasilia, Brasil Juan Pérez El Colegio de la Frontera Sur, Chiapas, México Montserrat Pérez Instituto Español de Oceanografía, Vigo, España Omar Pérez Utah State University, Utah, United State of America Jorge O. Pierini Universidad Nacional del Sur, Bahía Blanca, Argentina Marcelo Pinheiro Universidade Estadual Paulista, São Paulo, Brasil Sheng-Ping Wang National Taiwan Ocean University, Keelung, Taiwan Guido Plaza Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile German Poleo Universidad Lisandro Alvarado, Barquisimeto, Venezuela Jesús Ponce Universidad Autónoma de Nayarit, Nayarit, México Ricardo Prego Instituto de Investigaciones Marinas, Vigo, España Laura Prosdocimi Universidad de Buenos Aires, Buenos Aires, Argentina José Possebon Universidad de São Paulo, São Paulo, Brasil Andre Punt University of Washington, Washington, United State of America Javier Quiñones Universidad de Concepción, Concepción, Chile Ilie Racotta Centro de Investigaciones Biológicas del Noroeste, La Paz México Joana Raimundo Instituto Português do Mar e da Atmosfera, Lisboa, Portugal Sebastián Reyes Universidad Austral de Chile, Valdivia, Chile Francisco Rocha Universidad de Vigo, Vigo, España Gustavo Rodríguez Universidad Autónoma de Sinaloa, Sinaloa, México Jorge Rodríguez Instituto Politécnico Nacional, Ciudad de México, México Sara Rodríguez Universidad Austral de Chile, Valdivia, Chile Uriel Rodríguez Research and Development Center, São Paulo, Brasil Pablo Rojas Instituto de Fomento Pesquero, Valparaíso, Chile Elizabeth Romagosa Instituto de Pesca, São Paulo, Brasil Giovanna Romano Stazione Zoologica Anton Dohrn, Napoli, Italia María Soledad Romero Universidad Católica del Norte, Coquimbo, Chile Erich H. Rudolph Universidad de Los Lagos, Osorno, Chile Guilerme Rupp Universidade Federal de Santa Catarina, Florianópolis, Brasil Italo Salgado Universidad Católica de Temuco, Temuco, Chile Arturo Sánchez Centro de Investigaciones Biológicas del Noroeste La Paz, Baja California Sur, México Pedro Saucedo Centro de Investigaciones Biológicas del Noroeste La Paz, Baja California Sur, México Kurt Schaefer Inter-American Tropical Tuna Commission California, United State of America Rodrigo Schveitzer Universidad de São Paulo, São Paulo, Brasil Manuel Segovia Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, México Chugey Sepulveda Institute of Environmental Research, Oceanside United State of America Roger Sepulveda Universidad Austral de Chile, Valdivia, Chile Abilio Soares-Gomes Universidade Federal Fluminense, Niterói, Brasil Leonardo Tachibana Instituto de Pesca, São Paulo, Brasil María Isabel Toledo Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile Natalia Trabal Centro de Investigaciones Biológicas del Noroeste La Paz, Baja California Sur, México Mauricio Urbina University of Canterbury, Mánchester, United Kingdom Ivan Valdevenito Universidad Catolica de Temuco, Tamuco, Chile Marcia Vanacor Instituto Capixaba de Pesquisa, Vitória, Brasil Teodoro Vaske Junior Universidade Federal de Pernambuco, Pernambuco, Brasil Luz A. Velasco Universidad del Magdalena, Santa Marta, Colombia María Vega Instituto Politécnico Nacional, Yucatán, México Maria Teresa Viana Universidad Autónoma de Baja California, Ensenada, México Felipe Vieira Universidad Federal de Santa Catarina, Florianópolis, Brasil Leandro Vieira Universidad de São Paulo, São Paulo, Brasil Manuel Villar Universidad de Granada, Granada, España Fresia Villalobos Universidad de Costa Rica, San José, Costa Rica Ingo Wehrtmann Universidad de Costa Rica, San José, Costa Rica Gabriela Williams Centro Nacional Patagónico, Chubut, Argentina Vernónica Williner Instituto Nacional de Limnología, Santa Fe, Argentina Roberto Zamora Instituto Tecnológico de Conkal, Yucatán, México Escuela de Ciencias del Mar, Pontificia Universidad Católica de Valparaíso Casilla 1020, Valparaíso, Chile, Fax: (56-32) 2274206, E-mail: [email protected] LATIN AMERICAN JOURNAL OF AQUATIC RESEARCH Lat. Am. J. Aquat. Res., 43(5) 2015 CONTENTS Reviews Erich H. Rudolph Current state of knowledge on Virilastacus species (Crustacea, Decapoda, Parastacidae). Estado de conocimiento de las especies de Virilastacus (Crustacea, Decapoda, Parastacidae)…………………………………..………………….…………807-818 Marcelo García-Guerrero, Rodolfo de los Santos Romero, Fernando Vega-Villasante & Edilmar Cortes-Jacinto Conservation and aquaculture of native freshwater prawns: the case of the cauque river prawn Macrobrachium americanum (Bate, 1868). Conservación y cultivo de especies nativas de langostinos: el caso del cauque Macrobrachium americanum (Bate, 1868).……………………..………………………………………………………………………….………..819-827 Research Articles Rafael Vieira de Azevedo, Karolina dos Santos-Costa, Karen Figueiredo de Oliveira, Fábio Flores-Lopes, Eduardo Arruda Teixeira-Lanna & Luís Gustavo Tavares-Braga Responses of Nile tilapia to different levels of water salinity. Respuestas de la tilapia del Nilo a diferentes niveles de salinidad del agua………………………………………………………………………………………...…………….………..…828-835 Italo Salgado-Leu & Albert G.J. Tacon Effects of different protein and carbohydrate contents on growth and survival of juveniles of southern Chilean freshwater crayfish, Samastacus spinifrons. Efecto de diferentes niveles de proteína y carbohidratos sobre el crecimiento y sobrevivencia de juveniles del camarón de río del sur de Chile, Samastacus spinifrons……………….……………….…836-844 Gema Hidalgo, Wilmer Toledo & Alejandro Granados-Barba Diversidad y distinción taxonómica de la macrofauna en fondos blandos de la plataforma norte y suroccidental cubana. Macrofaunal diversity and taxonomic distinctness in soft bottoms of the northern and southwestern Cuban shelf… 845-855 Norberto Capetillo-Piñar, Marcial Trinidad Villalejo-Fuerte & Arturo Tripp-Quezada Distinción taxonómica de los moluscos de fondos blandos del Golfo de Batabanó, Cuba. Taxonomic distinctness of softbottoms mollusks from Gulf of Batabanó, Cuba……………………………………………………………..….…………….…856-872 Laura Vidal, Adriana Vallarino, Ileana Benítez & Jorge Correa Implementación del plan estratégico Ramsar en humedales costeros de la Península de Yucatán: normativas y regulación. Implementation of the Ramsar strategic plan in coastal wetlands of the Península de Yucatán: regulations and normativity……………………………………………………………………………………….…………….…..….……………….873-887 Wilson Massamitu Furuya, Mariana Michelato, Ana Lúcia Salaro, Thais Pereira da Cruz & Valéria Rossetto Barriviera-Furuya Estimation of the dietary essential amino acid requirements of colliroja Astyanax fasciatus by using the ideal protein concept. Estimación de los requerimientos dietéticos de aminoácidos esenciales de colliroja, Astyanax fasciatus, basadas en el concepto de proteína ideal corporal………………………………………………………………………..….…………..…….888-894 Larissa G. Paiva, Luana Prestrelo, Kiani M. Sant’Anna & Marcelo Vianna Biometric sexual and ontogenetic dimorphism on the marine catfish Genidens genidens (Siluriformes, Ariidae) in a tropical estuary. Biometría sexual y dimorfismo ontogenético en el bagre marino Genidens genidens (Siluriformes, Ariidae), en un estuario tropical…………………………………………………………………………………………..…...……………….895-903 Emmanuel Villanueva-Gutiérrez, Luis Rafael Martínez-Córdova, Marcel Martínez-Porchas & Miguel Antonio Arvayo Efecto de la adición de un extracto acuoso de pionilla Lasianthaea podocephala en el cultivo del camarón blanco del Pacífico Litopenaeus vannamei en condiciones de laboratorio. Effect of the addition of an aqueous extract of the San Pedro Daisy Lasianthaea podocephala, in the culture of the Pacific white shrimp, Litopenaeus vannamei, under laboratory conditions………………………………….…………………………………….….……………………………..….…………….….904-911 www.scielo.cl/imar.htm www.lajar.cl Anayeli Gutiérrez-Dagnino, Antonio Luna-González, Jesús A. Fierro-Coronado, Píndaro Álvarez-Ruíz, María del Carmen Flores-Miranda, Saraí Miranda-Saucedo, Violeta Medina-Beltrán & Ruth Escamilla-Montes Efecto de la inulina y del ácido fúlvico en la supervivencia, crecimiento, sistema inmune y prevalencia de WSSV en Litopenaeus vannamei. Effect of inulin and fulvic acid on survival, growth, immune system, and WSSV prevalence in Litopenaeus vannamei.……………….……………………………………………………………………..….……………...….…912-921 Eulogio Soto, Williams Caballero & Eduardo Quiroga Composition and vertical distribution of metazoan meiofauna assemblages on the continental shelf off central Chile. Composición y distribución vertical de los ensambles de meiofauna metazoaria en la plataforma continental frente a Chile central.………………….……………..……….………………………………………………………………..….……………….…922-935 Huann Carllo Gentil-Vasconcelos & Marcos Tavares-Dias First study on infestation of Excorallana berbicensis (Isopoda: Corallanidae) on six fishes in a reservoir in Brazilian Amazon during dry and rainy seasons. Primer estudio de la infestación de Excorallana berbicensis (Isopoda: Corallanidae) en seis peces en un embalse del Amazonas brasileño durante las estaciones seca y lluviosa…………....…….…936-943 Ricardo Yuji-Sado, Fernanda Raulino-Domanski, Patricia Franchi de Freitas & Francielli Baioco-Sales Growth, immune status and intestinal morphology of Nile tilapia fed dietary prebiotics (mannan oligosaccharidesMOS). Crecimiento, estado inmunológico y morfología intestinal de la tilapia del Nilo alimentadas con prebióticos (mananoligosacáridos-MOS) en la dieta………………….………………………………………………………………..….……………….…944-952 Marcos F. Quiñones-Arreola, G. Fabiola Arcos-Ortega, Vicente Gracia-López, Ramón Casillas-Hernández, Charles Weirich, Terry Morris, Mariana Díaz-Tenorio & Cuauhtémoc Ibarra-Gámez Reproductive broodstock performance and egg quality of wild-caught and first-generation domesticated Seriola rivoliana reared under same culture conditions. Desempeño reproductivo y calidad de huevos en reproductores de origen silvestre y domesticado-F1 de jurel Seriola rivoliana bajo las mismas condiciones de cultivo………...….……………….953-962 Thiago Fernandes A. Silva, Thalita R. Petrillo, Jefferson Yunis-Aguinaga, Paulo Fernandes-Marcusso, Gustavo da SilvaClaudiano, Flávio Ruas de Moraes & Julieta R. Engrácia de Moraes Effects of the probiotic Bacillus amyloliquefaciens on growth performance, hematology and intestinal morphometry in cage-reared Nile tilapia. Efectos del probiótico Bacillus amyloliquefaciens en el crecimiento, hematología y morfometría intestinal en tilapias del Nilo criadas en balsa jaula…………………….……………………..……….……..….……………….963-971 July A. Suárez, Ligia E. Urrego, Andrés Osorio & Hiara Y. Ruiz Oceanic and climatic drivers of mangrove changes in the Gulf of Urabá, Colombian Caribbean. Controladores oceánicos y climáticos de cambios en los manglares en el Golfo de Urabá, Caribe colombiano….….….……………….972-985 Short Communications Felipe Becerril-Morales & Juan Pablo Alcántar-Vázquez Atypical feminized male's agonistic behavior relative to males and females of Nile tilapia (Oreochromis niloticus L.). Comportamiento agonístico de machos feminizados atípicos en relación a machos y hembras de tilapia del Nilo (Oreochromis niloticus L.)……………………………………..…………….………………………………….…………….…986-992 Alfredo Borie, Natalia P.A. Bezerra, Sebastian A.L. Klarian & Paulo Travassos Soundscape of a management and exploitation area of benthic resources in central Chile. Paisaje acústico de un área de manejo y explotación de recursos bentónicos en Chile Central……………..……………….……..….……...……….…993-997 María Angélica Larraín, Nelson F. Díaz, Carmen Lamas, Carla Uribe, Felipe Jilberto & Cristián Araneda Heterologous microsatellite-based genetic diversity in blue mussel (Mytilus chilensis) and differentiation among localities in southern Chile. Diversidad genética del mejillón (Mytilus chilensis) y diferenciación entre localidades del sur de Chile usando marcadores microsatélites heterólogos….………………..……………………….….……..….……….….…998-1010 Elizabeth Labastida, Dorka Cobián, Yann Hénaut, María del Carmen García-Rivas, Pedro P. Chevalier & Salima MachkourM´Rabet The use of ISSR markers for species determination and a genetic study of the invasive lionfish in Guanahacabibes, Cuba. Uso de marcadores ISSR para la determinación de especies y estudios genéticos del pez león, especie invasora en Guanahacabibes, Cuba………………………………..…………….………………………………….……..….………………1011-1018 www.scielo.cl/imar.htm www.lajar.cl Libertad Alzamora-Gonzales, Carolina de Amat-Herbozo, Erasmo Colona-Vallejos, Elizabeth Cervantes-Aguilar, Richard Dyer Velarde-Álvarez, Ronald Aquino-Ortega & Miguel Ángel Aguilar-Luis Método rápido para la cuantificación de leucocitos sanguíneos y su utilidad en la evaluación del estado de salud en trucha arcoíris Oncorhynchus mykiss. Rapid method for counting of blood leukocytes and its usefulness in health status assessment of rainbow trout (Oncorhynchus mykiss) …..………….…………………………….……..….………………1019-1023 Italo Fernández, Marco Antonio Retamal, Miguel Mansilla, Francisco Yáñez, Víctor Campos, Carlos Smith, Guillermo Puentes, Ariel Valenzuela & Hernán González Analysis of epibiont data in relation with the Debilitated Turtle Syndrome of sea turtles in Chelonia mydas and Lepidochelys olivacea from Concepción coast, Chile. Análisis de los datos de epibiontes en relación con el Síndrome de Debilitamiento de Tortugas marinas en Lepidochelys olivacea y Chelonia mydas de la costa de Concepción, Chile..1024-1029 www.scielo.cl/imar.htm www.lajar.cl Lat. Am. J. Aquat. Res., 43(5): 807-818, 2015 Current state of knowledge on Virilastacus species DOI: 10.3856/vol43-issue5-fulltext-1 807 Review Current state of knowledge on Virilastacus species (Crustacea, Decapoda, Parastacidae) Erich H. Rudolph1 Departamento de Ciencias Biológicas y Biodiversidad, Universidad de Los Lagos P.O. Box 933, Osorno, Chile 1 Corresponding author: Erich H. Rudolph ([email protected]) ABSTRACT. The genus Virilastacus was created in 1991 to accommodate Parastacus araucanius Faxon, 1914. At present, Virilastacus comprises four burrowing species, three of which were described at the beginning of the XXI century, and biological knowledge about these species is mainly limited to taxonomic and distributional aspects. This review compiles published information about these species, together with other data available to the author in order to update the current state of biological knowledge and, in turn, to promote the conservation of these species. An upgraded diagnosis of the genus Virilastacus is provided, together with information related to each species with regard to: distinctive morphological traits, geographic distribution, habitat, burrow morphology, burrowing behavior, body size, sexual system, and state of conservation. Some aspects related to morphological adaptations to their burrowing life style, phylogenetic affinities and main threats to conservation are also discussed. It is concluded that biological knowledge about these four species is scarce and fragmentary; furthermore, they are currently under threat as a result of anthropogenic activities that are degrading and fragmenting their habitat. Keywords: Virilastacus, burrowing crayfish, morphology characters, geographic distribution, sexual system, habitat, conservation status, Chile. Estado de conocimiento de las especies de Virilastacus (Crustacea, Decapoda, Parastacidae) RESUMEN. El género Virilastacus fue creado en 1991 para ubicar a Parastacus araucanius Faxon, 1914. Actualmente Virilastacus reúne a cuatro especies excavadoras, tres de ellas descritas a comienzos del siglo XXI, cuyo conocimiento biológico se circunscribe principalmente a aspectos taxonómicos y distribución. Esta revisión recopila la información publicada de estas especies, junto a otros datos accesibles al autor, para actualizar el conocimiento biológico y a la vez promover su conservación. Se proporciona una diagnosis actualizada del género, y de cada especie se entrega información sobre: rasgos morfológicos distintivos, distribución geográfica, hábitat, morfología de las galerías, comportamiento excavador, tamaño corporal, sistema sexual y estado de conservación. También se comentan algunas de las adaptaciones morfológicas a su estilo de vida excavador, sus afinidades filogenéticas y las principales amenazas a su conservación. Se concluye que el conocimiento biológico de estas cuatro especies es escaso y fragmentario, y que ellas se encuentran amenazadas por actividades antropogénicas que están degradando y fragmentando su hábitat. Palabras clave: Virilastacus, camarones excavadores, caracteres morfológicos, distribución geográfica, sistema sexual, hábitat, estado de conservación, Chile. INTRODUCTION At the beginning of the XX century, 10 species of the family Parastacidae had been described for South America, all grouped within one genus: Parastacus. Riek (1971) separated them into the genera Samastacus _______________________ Corresponding editor: Ingo Wehrtmann and Parastacus; he assigned two species [Parastacus spinifrons (Philippi, 1882) and Parastacus araucanius Faxon, 1914] to the genus Samastacus, in view of the following characteristics: P1 dactyls moving horizontally and phallic papillae being relatively long, articulated tubular projections. The other species, whose 808 Latin American Journal of Aquatic Research dactyls move vertically and phallic papillae are only small non-articulated protuberances, remained within Parastacus. Additionally, Riek (1971) characterized these genera in ecological terms: the Parastacus species as burrowers and inhabitants of underground waters, while the Samastacus species were characterized as weak burrowers, inhabiting rivers and lakes. After a period of 69 years, during which the only knowledge about Samastacus araucanius (Faxon, 1914) was based on the type specimen, Jara (1983) collected a second specimen, a male captured in the Botanical Gardens of the Universidad Austral de Chile (Valdivia), cohabitating with Parastacus nicoleti (Philippi, 1882). Rudolph & Rivas (1988) collected the third representative of this species, also a male in Hualqui (Concepción) cohabiting with Parastacus pugnax (Poeppig, 1835). These discoveries provided sufficient evidence to exclude the occurrence of S. araucanius in open waters, as had been suggested in Faxon’s (1914) description of the location where the type material was obtained: “in a waterfall in Corral”. Based on this evidence, as well as on morphological differences [which were already mentioned by Jara (1983) and Rudolph & Rivas (1988)], Hobbs (1991) separated these two species into the genera Samastacus (S. spinifrons) and Virilastacus (V. araucanius); this author also provided diagnoses of the three South American genera of Parastacidae. Crandall et al. (2000) validated these three genera, based on the sequencing of 500 nucleotides of the 16S mitochondrial DNA gene in seven of the ten species of South American parastacids. Rudolph & Crandall (2005, 2007, 2012) described three new species of Virilastacus, extended their geographic range, and confirmed that all the species of this genus were burrowers. In the present review, the scarce information published on the Virilastacus species is compiled and systematized, together with other data available to the author, with the aim to update the biological knowledge about this species and, in turn, to promote effective conservation measures. Family Parastacidae Huxley, 1879 Genus Virilastacus Hobbs, 1991 Diagnosis Rostrum short. Carapace lacking spines, tubercules and postorbital ridges; anterolateral portion of branchiocardiac groove clearly separated from the portion subparallel to cervical groove, which is located close to upper third portion of cephalothorax. Viewed dorsally, cervical groove V-shaped, except in V. retamali. Pleon lacking spines and tubercles; pleura of first abdominal segment distinct from and partly overlapped by that of the second abdominal segment. Telson without transverse suture and wholly calcified; posterior half with dorsomedian longitudinal groove. Ventral surface of ischipodite of third maxilliped bearing a median longitudinal band of tubercules; inside half of this surface with tufts of rigid setae; distolateral end of podomere rounded, except in V. jarai; merus lacking spines or tubercules; exopodite reaches distal end of merus. Caudal molar process of mandible quadricuspid in V. araucanius and V. jarai; tricuspid in V. rucapihuelensis and V. retamali; nodular cusp on proximal margin of cuspidal triangle. P1 chelae dimorphic, with almost completely tuberculated palms, but lacking spines or large tubercules; ventrolateral borders tuberculated to slightly subtoothed; carpus lacking large tubercules medially or ventrally, when upper surface held in a horizontal plane, dactyl moving obliquely in V. rucapihuelensis and V. jarai, and subhorizontally in V. araucanius and V. retamali. No occurrence of male and female gonopores in the same individual, except in V. rucapihuelensis. Male genitalia with a semi-rigid, tubular, thin, articulated, and very long phallic papilla extending forward from coxae in very close proximity to each other; lacking male cuticle partition, except in V. rucapihuelensis. Sternite XIII with an anterior medial plate, and posterior orifice. Viewed caudally, lateral processes of sternite XIV separated by a pronounced vertical fissure. Type species. Parastacus araucanius Faxon, 1914: 553 Gender: Male Etymology. From the Latin virilis = masculine; socalled because of its comparatively long phallic papilla (Hobbs, 1991; Rudolph & Crandall, 2012). Virilastacus araucanius (Faxon, 1914) (Fig. 1a) Common name: Dwarf crayfish Synonymy Parastacus araucanius Faxon, 1914: 353, pp. 4, Figs. 1-3; Van Straelen, 1942: 9; Holthuis, 1952: 84; Bahamonde & López, 1963: 126 and 127, maps 1 and 2; Jara, 1983: R-163. Samastacus araucanius Riek, 1971: 135; Manning & Hobbs, 1977: 159; Rudolph & Rivas, 1988: 73, Fig. 1; Hobbs, 1989: 80, Fig. 374; Buckup & Rossi, 1993: 167, Figs 11-13; Martínez et al., 1994: 9, Figs. 1-11. Distinctive morphological characteristics Cephalothorax smooth, coloration: olive green. Small eyes. Rostrum short, reaching distal end of middle podomere of antennal flagellum; dorsally excavated. Rostral carina long and slightly prominent. Cervical groove weakly “V” shaped. Areola narrow and extended. Antennal scale short with one small distolateral spine. Basal podomere of antennula lacking Current state of knowledge on Virilastacus species 809 Figure 1. Virilastacus araucanius (Faxon, 1914). a) Dorsal view of male. Scale bar = 17.9 mm, b) partial view of habitat, c) overhead view of chimneys. Photos: E. Rudolph. spines. Opposable margin of propodite without pilosity, bearing 11 to 18 teeth; dactyl moving sub horizontally, opposable margin bearing nine to 15 teeth. Individuals with female or male gonopores. Elongated phallic papilla reaches base of lateral process of XII body segment. In males, P5 coxae lack cuticle partition. Pleon coloration light brown. Telson subrectangular, dorsomedian longitudinal groove, and prominent spine on each lateral border (Faxon, 1914; Riek, 1971; Hobbs, 1991; Rudolph & Crandall, 2012). Species relatively small. The largest specimen caught is a female, measuring 28.7 mm cephalothorax length (CL) (74.8 mm total length). The smallest specimen collected is also a female, 18.3 mm CL (Martínez et al., 1994). In the case of males, maximum and minimum sizes recorded are 26.0 and 19.0 mm CL respectively (Faxon, 1914; Jara, 1983). A summary of distinctive morphological features of the four species of Virilastacus is provided in Table 1. Geographic distribution V. araucanius has been recorded from areas surrounding Concepción (36°46’22”S, 73°03’47”W), Valdivia (39°48′30″S, 73°14′30″W), and Maicolpué (40°36’27,74”S, 73°44’01,44”W) (Faxon, 1914; Jara, 1983; Rudolph & Rivas, 1988; Hobbs, 1991; Martínez et al., 1994; Bahamonde et al., 1998). This discontinuous distribution may only be apparent, since it coincides with the presence of university research centers in these three areas (Jara et al., 2006). Nevertheless, recordings of V. araucanius in Maicolpué (Bahamonde et al., 1998) should be reviewed, given that they may correspond to specimens of either V. rucapihuelensis or V. retamali, described after the studies of Bahamonde et al. (1998), in a location (Rucapihuel) situated only 15 km from Maicolpué. Finally, recordings of V. araucanius suggest that it is distributed between the coast and the Coastal Cordillera mountain range; the extent of occurrence is estimated at 11.571,64 km2 (Ministerio del Medio Ambiente, 2013a). Habitat V. araucanius inhabits underground waters in topographic basins with evergreen lowland forest associations. Almost all recordings of this species occur in these biotopes, commonly referred to as “vegas” or “hualves” (Fig. 1b). Only the discovery of V. araucanius in the Botanical Gardens of the Universidad Austral de Chile in Valdivia (Jara, 1983; Hobbs, 1991) indicates its presence in flatter zones, subject to considerable anthropic intervention. Specimens of this species have also been found coexisting with P. nicoleti (Jara, 1994; Jara et al., 2006) in the same Botanical Gardens. A similar situation occurs in the locality of Hualqui (46o56´S, 72o55´W), where specimens of V. araucanius have been found cohabiting with P. pugnax (Rudolph & Rivas, 1988). Burrow morphology The burrows constructed by V. araucanius are shallow (<1 m), but quite complex, with multiple ramifications, many of them almost parallel to the surface, which complicates their capture, whether manually or by suction methods. In winter, V. araucanius constructs mud “chimneys” 2.0-6.0 cm high, located around the entrance orifices of their burrows (Jara, 1994) (Fig. 1c). According to the classification of burrowing crayfish 810 Latin American Journal of Aquatic Research proposed by Hobbs (1942), V. araucanius would be a primary burrower, since it builds complex burrows are not connected to permanent water bodies, and the entire life cycle of this species occurs inside the burrows. Sexual system Descriptions of external sexual characteristics, together with some anatomical analyses of gonads and gonoducts, suggest that V. araucanius is a gonochoric species. Adult females have ellipsoidal gonopores, partially surrounded by setae and covered by a noncalcified membrane. These characteristics, suggesting the occurrence of functional gonopores, are very similar to those observed in V. rucapihuelensis adult females (Rudolph et al., 2007). Males have an elongated, calcified phallic papilla ( = 3.1 ± 0.4 mm; n = 12) and the respective gonopore opens at the apical end (Rudolph & Rivas, 1988; Hobbs, 1991; Martínez et al., 1994; Rudolph & Almeida, 2000). Conservation status Bahamonde et al. (1998) categorized V. araucanius as Insufficiently Known throughout its entire geographic range. Nevertheless, they warned that water pollution and substrate modification within its distribution area could cause negative effects on the conservation of these populations. Rudolph & Crandall (2007) classified the species as Vulnerable through its geographic distribution range, based on the B1ab (iii) criteria of the IUCN Red List (2001). Buckup (2010a) classified it as Data Deficient. The Ministerio de Medio Ambiente (2013a) described it as Vulnerable, in accordance with the B1ab (iii) + 2ab (iii) criteria of the IUCN Red List (2001). Finally, Almerao et al. (2014) also endorsed this latter categorization. Virilastacus rucapihuelensis Rudolph & Crandall, 2005 (Fig. 2a) Common name: Vega crayfish Synonym: Virilastacus araucanius Rudolph & Rojas, 2003: 835, Figs. 1-8 Distinctive morphological characteristics Cephalothorax with small tubercles only in anteroventral regions of branchiostegites. Small eyes. Rostrum short, reaching distal margin of basal podomere of antennal flagellum; dorsally concave. Rostral carina long and prominent. Epistome anteromedian lobe resembles a triangle. Cervical groove “V” shaped. Basal podomere of antennula with small spine. Dorsal surface of P1 carpus with faint median groove, opposable margin of propodite bearing 5 to 9 teeth with pilosity on both sides, but only of their proximal group, dactyl moving obliquely. Abdominal pleura ventral Figure 2. Virilastacus rucapihuelensis Rudolph & Crandall, 2005. a) Dorsal view of specimen. Scale bar = 14.0 mm, b) partial view of habitat. Photos: E. Rudolph. margins almost straight. Individuals with supernumerary gonopores. In adult females, pleura of second pleomere with wide anteroventral flap, weakly calcified. Males with slightly elongated phallic papillae that reach the base of the P4 coxae. In males, P5 coxae with cuticle partition. Telson subrectangular, lateral margins almost parallel, each of them with a small, blunt spine. Light brown body coloration (Rudolph & Crandall, 2005, 2012). This species is slightly larger than V. araucanius. The largest specimen collected (33.6 mm CL) is an intersex individual in female phase and the smallest, a primary female with 4.4 mm CL (Rudolph et al., 2007) (Table 1). Geographic distribution This species has been reported from five nearby sites in the Coastal Cordillera of the province of Osorno, southern Chile: Rucapihuel (40°35’00.64”S, 73°34’42. 96”W), Coiguería (40°35’17.62”S, 73°32’10.00”W), Carrico (40°35’34.14”S, 73°31’19.70”W), Contaco (40°36’01.50”S, 73°31’00.97”W), and Loma de la Piedra (40°40’13.59”S, 73°30’51.42”W) (Rudolph & Crandall, 2005; Grosso & Peralta, 2009). The extent of Current state of knowledge on Virilastacus species 811 Table 1. Morphological characters useful for distinguish the four presently identified species of Virilastacus (Modified from Rudolph & Crandall, 2012). Character V. araucanius V. rucapihuelensis V. retamali V. jarai Excavated Long and not very prominent Small Short. Distolateral spine small Spine absent Concave Long and prominent Concave Short and prominent Small Short. Distolateral spine small Small spine Large Long. Distolateral spine large Large spine Concave Short and little prominent Small Short. Distolateral spine small Large spine Molariform Quadricuspide Dentiform Tricuspide Molariform Tricuspide Molariform Quadricuspide Resembles a rhombus With anterolateral tubercles small Resembles a triangle With anterolateral tubercles small Resembles a rhombus With anterolateral tubercles large Resembles a rhombus With anterolateral tubercles large External distal border With a band of small, blunt tubercules and scarce pilosity Without extension With a band of small, blunt tubercles and scarce pilosity Without extension With a band of large, prominent tubercles and abundant pilosity Without extension With a band of small, blunt tubercles and abundant pilosity With a large extension Opposable Propo margin Pilosity Absent Only on both sides of the proximal group of teeth On both sides of the entire row of teeth Number of teeth Between 11 and 18 Between 5 and 9 Between 13 and 17 Throughout the dorsal side and only on the basal zone of the ventral side Between 11 and 22 Dactylus Movement Number of teeth Precervical cephalothorax Subhorizontal Between 9 and 15 Dorsal ridges absent Oblique Between 5 and 10 Dorsal ridges absent Subhorizontal Between 10 and 15 With 4, smooth dorsal ridges Narrow and extended Weakly V-shaped Close together Female or male In close proximity, long and thin Absent Narrow and extended Strongly V-shaped Widely separated Supernumerary Widely separated, more robust and shorter Present Wide and short U-shaped Close together Female or male Very close together, very long and thin Absent Oblique Between 9 and 15 With 4 smooth dorsal ridges, or with 2, or absent Wide and extended Strongly V-shaped Close together Female or male Very close together, long and thin Absent With a small anterior lobe, partially overlapped by the S2 pleuron Anterior lobe absent, not overlapped by S2 pleuron Flap absent Flap present With a small anterior lobe, partially overlapped by the S2 pleuron Flap absent With a small anterior lobe, total or partially overlapped by S2 pleuron Flap absent Subretangular Prominent and sharp Semi-marshland, perennially green areas Subretangular Small and blunt Semi-marshland, perennially green areas Subtriangular Prominent and sharp Peatlands Subtriangular Small and sharp Fragment semimarshland, perennially green areas Rostrum Dorsodistal surface Rostral carina Eyes Antennal scale Basal Podomere Antennula Mandible Cephalic molar process Caudal molar process Epistome Anteromedial lobe Posterior plate Ischium of Maxilliped 3 Ventral surface Areola Cervical groove P4 Coxae Gonopores Phallic Papillae Male Cuticle Partition Pleomere pleura Somite 1 Somite 2 of the adult females Telson Form Lateral spines Habitat 812 Latin American Journal of Aquatic Research their occurrence covers 39.3 km2 (Ministerio de Medio Ambiente, 2013b). Habitat V. rucapihuelensis inhabits underground waters in biotopes locally called “vegas” or “hualves” (Rudolph & Crandall, 2005) (Fig. 2b). The soil profile of the “vegas” located in Rucapihuel includes two layers composed of fine clay sand. The upper layer comprises abundant iron oxides, the lower layer (80 cm below the soil surface) is of sandy gravel. In the winter, the phreatic level is close to or above the surface, and in summer, it descends as far as 1.0 or 1.5 m below the surface (Bedatou et al., 2010). After carrying out yearround monthly recordings of some physicochemical parameters of the water inside the burrows, Martínez (2005) verified that temperature fluctuated between 11 y 19°C, pH between 4.1 and 5.3, and dissolved oxygen between 2.6 and 6.5 mg L-1; on the other hand, total hardness remained constant at 17.8 ppm de CaCO3. Burrow morphology and burrowing behavior The burrow morphology is variable. Some have several relatively complex entrance orifices (diameter 2.5-3.5 cm) with multiple ramifications in the subsoil. Some of these connected to a terminal chamber with a slightly larger diameter than the tunnel, situated between 1 and 1.2 m below the surface. Others are blind tunnels (Type 1 burrow, Fig. 3a). Other burrows have only one subvertical tunnel (3 to 4.5 cm diameter and up to 66 cm depth) with a few blind tunnels emerging from the uppermost section. The lower terminal section of this system is a sub-horizontal chamber with a slightly wider diameter than the tunnel (Bedatou et al., 2010) (Type 2 burrow, Fig. 3b). V. rucapihuelensis forms small pellets (8-10 mm maximum diameter) from the excavated material, and these pellets are deposited in the winter around the entry orifices of the burrows, forming “chimneys” of up to 12 cm height (Rudolph & Crandall, 2005) (Fig. 3c), these burrows are usually inhabited by one specimen; nevertheless, in springsummer, it may be possible to find a female with a variable number of recently released juveniles in some of these burrows. According to Hobbs´ (1942) classification, aspects such as excavating complex burrows, distanced from permanent water bodies, together with no recordings of specimens outside the burrows, suggest that this species can be considered as a primary burrower. Sexual system V. rucapihuelensis presents partial protandric hermaphroditism with primary males and females (Rudolph Figure 3. Virilastacus rucapihuelensis Rudolph & Crandall, 2005. a) Lateral view of mould type 1 burrow, b) lateral view of mould type 2 burrows, c) overhead view of chimney. Arrowheads = surface entrances. Photos: a) and b) E. Bedatou; c) E. Rudolph. et al., 2007). Depending on the presence or absence of gonopores in the P3 and P5 coxae; externally, six sexual forms may be distinguished. Anatomical analyses of the gonads and gonoducts of these sexual forms enabled us to ascertain the presence of three basic sexual types: primary males, primary females, and intersex specimens. These latter comprise one malephase and two female-phase forms, that would originate from male-phase intersex individuals (Rudolph et al., 2007). Fecundity The species produced up to 74 eggs, incubated by a primary female of 27.9 mm CL. The lowest fecundity (three eggs) observed was in a primary female of 23.1 mm CL (Rudolph et al., 2007). Conservation status Rudolph & Crandall (2007), based on the B1 ab (iii) criteria of the IUCN Red List (2001), classified V. rucapihuelensis as Endangered in its entire distribution range, while Buckup (2010b) classified it as Data Deficient. The Ministerio de Medio Ambiente (2013b) classified it as Endangered, maintaining that it meets the B1 ab (iii) + 2ab (iii) criteria of the IUCN Red List (2001). Finally, Almerao et al. (2014) suggested that V. rucapihuelensis is Critically Endangered, considering that it falls within the B1 ab (iii) criteria associated with this category. Current state of knowledge on Virilastacus species 813 Figure 4. Virilastacus retamali Rudolph & Crandall, 2007. a) Dorsal view of specimen. Scale bar = 12.0 mm, b) partial view of habitat, c) lateral view of chimney. Photos: E. Rudolph. Virilastacus retamali Rudolph & Crandall, 2007 (Fig. 4a) Common name: Peatland crayfish Distinctive morphological characteristics Precervical cephalothorax with four smooth ridges. Eyes comparatively large. Rostrum short reaches distal margin of middle podomere of antennal flagellum; dorsally concave. Rostral carina short and prominent. Cervical groove “U” shaped. Areola wide and short. Antennal scale long with large distolateral spine. Epistome anteromedian lobe resembling a rhombus. Basal podomere of antennula with large spine. Opposable margin of P1 propodite bearing 13 to 17 teeth, with pilosity on both sides of the row of teeth. Dactyl moving subhorizontally. Abdominal pleura with rounded ventral margins. Telson with converging lateral margins resembling a triangle, with prominent, sharp marginal spines. Individuals with female or male gonopores. Phallic papillae very elongated, reaching as far as the base of the P3 coxae. Males without cuticular partition in P5 coxae. Cephalothorax dark-olive green and pleon light olive green (Rudolph & Crandall, 2007, 2012). Species is small (17.9-30.0 mm CL; = 21.1 ± 3.0 mm CL; n = 21), but the only size data available derives from the type series specimen (Rudolph & Crandall, 2007) (see Table 1). Geographic distribution This parastacid, recorded in two Coastal Cordillera localities in the provinces of Osorno and Llanquihue, southern Chile: Rucapihuel (40º35’00.08”S, 73º34’ 44.3”W), and Estaquilla (41º25’15.93”S, 73º46’51. 74”W) (Rudolph & Crandall, 2007) extends its occurrence approximately 3.200 km2 (Rudolph, 2010). Habitat Both of these V. retamali populations inhabit geogenous peatlands, i.e., depend on rainwater and superficial underground waters to supply hydric needs (Kulzer & Cook, 2001). These peatlands originated in a small endorreic basin generated by the holocenic deglacialization where, over the course of time, organic matter has been deposited (Grignola & Ordoñez, 2002). This organic material originated from the partially decomposed, loosely compacted vegetal remains of the genus Sphagnum, mixed with woody fragments, gramineous and humus particles, accumulated in an anoxic environment, highly saturated with water all year round (Grignola & Ordoñez, 2002) (Fig. 4b). On capturing the type series, (17 December 2002), the water analyzed inside the burrows had a pH of 4.7, dissolved oxygen of 2.8 mg L-1, constant hardness of 17.8 ppm of CaCO3, and a temperature of 12.5ºC (Rudolph & Crandall, 2007). Burrow morphology Virilastacus retamali excavates shallow burrows (45 cm depth approximately) with few ramifications. A mold made with polyester resin (Bedatou et al., 2010) revealed six main entrances, with diameters ranging from 3.0 to 3.5 cm. Fifteen centimeters below the surface, three of these entrances converged into a short, subhorizontal tunnel; one of its ends projected slightly upwards to form a short blind tunnel; the other extreme is connected to a main sub-horizontal tunnel. The remaining three entrances converged at a depth of 30 cm, at the other end of the main tunnel. In the winter, the species constructs “chimneys” reaching an average height of 3.9 cm (SD = ± 0.729; n = 8) (Fig. 4c). Unlike the other species of the genus, V. retamali has been observed and captured outside its burrows, in nearby 814 Latin American Journal of Aquatic Research surface pools. Based on these observations and according to Hobbs´s criteria (1942), V. retamali can be categorized as a secondary burrowing species (Rudolph & Crandall, 2007). Sexual system No external morphological evidence of intersexuality has been detected in the type series (Rudolph & Crandall, 2007), suggesting that this species is gonochoric. Females smaller than 20.0 mm CL have strongly calcified semi-ellipsoidal gonopores, while females larger than 20.0 mm CL have apparently functional ellipsoidal gonopores, given that they are only partially calcified and surrounded by abundant pilosity. Males have a very elongated phallic papilla ( = 3.5 ± 0.5 mm) (Rudolph & Crandall, 2007). Conservation status Rudolph & Crandall (2007) classified V. retamali as an Endangered throughout its entire geographic range, given that it would meet the B1 ab(iii) criteria of the IUCN (2001) Red List for this category. Nevertheless, Buckup (2010c) classified it as Data Deficient, while Almerao et al. (2014) supported the endangered species classification of Rudolph & Crandall (2007). Virilastacus jarai Rudolph & Crandall, 2012 (Fig. 5a) Common name: Angeline crayfish Distinctive morphological characteristics Precervical cephalothorax with four, two or lacking smooth dorsal ridges. Eyes small. Rostrum short, reaching distal margin of the middle podomere of antennal flagellum; dorsally concave. Rostral carina short, weakly prominent. Epistome anteromedial lobe resembling a rhombus. Cervical groove “V” shaped. Areola wide and extended. Opposable margin of P1 propodite bearing 11 to 22 teeth with pilosity along the length of dorsal side, while only on basal part of ventral side. Dactyl moving obliquely. Abdominal pleura with straight ventral margins. Telson subtriangular with a small, sharp spine in each lateral margin. Individuals with female or male gonopores. Phallic papillae elongated, reaching base of lateral process of XII body segment. Males lacking cuticular partition in P5 coxae. Cephalothorax and P1 chelipeds olive green. Pleon and caudal fan light brown (Rudolph & Crandall, 2012). It is a small species; size in the type series ranges from 6.7 to 24.8 mm CL ( = 17.5± 6.1 mm) (Rudolph & Crandall, 2012) (see Table 1). Geographic distribution Virilastacus jarai has only been recorded in the type locality, a fragment of wetland situated in the “El Porvenir” sector (37º26’39.84”S, 72º18’37.12”W), 1.5 km northwest of the town of Los Ángeles in centralsouthern Chile (Rudolph & Crandall, 2012). Habitat The species inhabits the underground waters of a fragment of semi-marshland, located in a topographic basin of 861 m2 at 152 m above sea level. This area is flooded for six months of the year (May to October) and the phreatic level remains below the surface in springsummer (Fig. 5b). The soil, characterized by a large accumulation of organic material, in addition to the high percentage of moisture originating from partially decomposed vegetal remains. On capturing the type series (13 June 2010), analysis of the water inside the burrows was as follows: dissolved oxygen = 4.9 mg L-1, temperature = 14.1ºC, pH = 6.5, and constant hardness of 53.4 ppm of CaCO3 (Rudolph & Crandall, 2012). Burrowing behavior The species excavates shallow (<1 m), but complex burrows, not connected to lothic or lenthic waters (Rudolph & Crandall, 2012). In winter, it also constructs “chimneys” around the entrance orifices of the burrows (Fig. 5c). Outside the burrows, no specimens have been found, which suggest that the entire life cycle of V. jarai occurs inside the burrows. According to the Hobbs´s (1942) criteria, the species can be considered as a primary burrower. Sexual system The revision of the type series revealed the occurrence of an intersex individual; however, this is not sufficient evidence to maintain that this is a transitional stage of an eventual sex change or, even less likely, that the species presents some form of hermaphroditism. Consequently, the evidence available suggests that V. jarai would be a gonochoric species (Rudolph & Crandall, 2012). Conservation status Rudolph & Crandall (2012) categorized V. jarai as Critically Endangered. This conclusion was based on the B1ab (ii) criteria of the IUCN Red List (2001) for this category, i.e., an estimated extent of occurrence of less than 100 km2, only known recording in one location, and a projected decline in habitat quality. The V. jarai habitat has been subject to deforestation in the recent past to clear land for agricultural purposes. At present, this land has been divided up and the topography modified to accommodate building development projects resulting from the rapid expansion of the town of Los Ángeles. Almerao et al. (2014) endorsed categorizing V. jarai as a critically endangered species. Current state of knowledge on Virilastacus species 815 Figure 5. Virilastacus jarai Rudolph & Crandall, 2012. a) Dorsolateral view of specimen. Scale bar = 9.0 mm, b) partial view of habitat, c) lateral view of chimney. Photos: E. Rudolph. REMARKS The four Virilastacus species are endemic to Chile and have a restricted geographic range, distributed between the coastline and the Coastal Cordillera, from Concepción (36o46’S) to Estaquilla (41o25’S), except for V. jarai, whose presence has only been recorded in one location, to the east of the coastal Cordillera (Fig. 6). Furthermore, within this coastal fringe, populations present a clearly discontinuous distribution, associated with wetlands. These species are burrowers, and although their burrows are shallow (<1.5 m), have multiple ramifications and are much elaborated (Bedatou et al., 2010). The most significant morphological adaptations to this life style include the following aspects: (1) body without large protuberances, facilitating their movement inside the tunnels; (2) highly developed cephalothorax, in comparison to the scarcely developed pleon; (3) cephalothorax taller than broad, which increases the volume of the branchial chamber and makes it possible to house larger branchia than those species that inhabit open waters; (4) P1 chelae relatively large and vertically orientated, and (5) reduced eye size (Rudolph, 1997; Reynolds et al., 2013). They also share some biological characteristics of all freshwater astacids (Families Astacidae, Cambaridae and Parastacidae) such as: low fecundity, direct development with hatching in the juvenile stage, extended parental care up to the second juvenile stage, as well as omnivorous feeding habits (Rudolph & Rojas, 2003; Rudolph, 2013). Like the other species of these three families, they are very important functional elements in the linmic ecosystems, both as prey and as consumers (Jara et al., 2006; Almerao et al., 2014). Nevertheless, Figure 6. Geographical distribution of Virilastacus species. Gray fringe = Virilastacus araucanius; ● Virilastacus jarai; □ Virilastacus rucapihuelensis;▐ Virilastacus retamali. 816 Latin American Journal of Aquatic Research biological knowledge about these species is limited mainly to taxonomic and distributional aspects, with some information about their sexual system. Three of the four species have separate sexes while V. rucapihuelensis presents partial protandric hermaphroditism, with primary males and females (Rudolph et al., 2007). Similarly, some information has been acquired about their phylogenetic affinities (Rudolph & Crandall, 2007, 2012). Reconstruction of phylogenetic relationships revealed the monophyly of the Virilastacus genus and of each one of its species. Furthermore, they showed that there is clear genetic differentiation between V. jarai and the other species of the genus. Virilastacus jarai is situated in a different basal clade with respect to the clade of the other three species, with V. araucanius being the species phylogenetically closest to V. jarai. Moreover, the incubation period of V. rucapihuelensis and probably that of the other three species extends from mid-winter to mid-summer (from July to February) (Rudolph et al., 2007). Recently, the Ministerio del Medio Ambiente (2013a, 2013b) and Almerao et al. (2014), based on the IUCN (2001) Red List criteria, have reevaluated and updated the state of conservation of Chilean and South American parastacids, respectively. Notwithstanding these updates, no effective measures for their protection have been implemented yet and, as a result, the conservation of the Virilastacus species is still under threat. Included among these threats are: (1) drainage of the “vegas” for forestry, farming and livestock development; (2) use of chemicals (agricultural fertilizers and pesticides); (3) clearing of vegetation and subsequent replacement of vegetation coverage; (4) free-range pig farming, which removes the original vegetation and compacts the soil, and (5) cattle farming, with trampling and destruction of the burrows. These threats are degrading, fragmenting, and ultimately decreasing the geographical extension of their habitat. Furthermore, certain intrinsic characteristics of parastacids [i.e., slow growth, low fecundity, delayed sexual maturity and long periods of embryonic and early post-embryonic development (Holdich, 1993; Rudolph, 2013)], together with the restricted geographic range and scarce mobility of the Virilastacus species, render them particularly vulnerable to the aforementioned threats. At present, the Chilean parastacids in general, and the Virilastacus species in particular, are not threatened by invasive exotic species (Rudolph, 2013). However, this threat could materialize in the near future, if we consider that Procambarus clarkii (Girard, 1852), a species native to North America and with considerable adaptive plasticity, has been introduced successfully to almost all continents, and has already been recorded in Colombia, Ecuador and Brazil (Valencia-López et al., 2012; Almerao et al., 2014). Furthermore, recent studies revealed numerous areas in the southern cone of South America (Argentina, Paraguay, Uruguay, and Chile) suitable for P. clarkii occupation (Palaoro et al., 2013). Fortunately, these four species are not under threat from fishery activities for human consumption, because they are small species whose edible part (the pleon) is underdeveloped, thus, meat yield is very meager; these species also construct very complex burrows and considerable effort is required to capture them. Finally, part of their geographic range is located to the south of the Toltén River (39oS), where the local inhabitants have no tradition of consuming these types of crustaceans. Could this lack of socio-economic significance account for the lack of legislation regulating their protection? Probably not considering that other Chilean parastacids exposed to elevated extraction pressure for human consumption purposes (i.e., Samastacus spinifrons and Parastacus pugnax) and neither is protected. Minimum biological knowledge (distribution range, habitat type, life style, size, incubation period, and state of conservation) necessary to establish regulations is now available. Legislation in this respect, together with regulating compliance with the law, would greatly contribute towards the conservation of Chilean parastacids. It is believed that protection of these species can be achieved, considering that the Ministry of Environment has announced a series of measures in both the National Plan of Action on Climate Change and the draft law for the creation of a Biodiversity and Protected Areas Service. ACKNOWLEDGEMENTS The author is grateful to the Research Department of the Universidad de Los Lagos, Osorno, Chile, for financially supporting many of the studies carried out on Virilastacus, in addition to the publication of this article. The collaboration of Susan Angus with the translation of the paper is appreciated. REFERENCES Almerao, M.P., E. Rudolph, C. Souty-Grosset, K. Crandall, L. Buckup, J. Amouret, A. Verdi, S. Santos & P.B. Araujo. 2014. The native South American crayfishes (Crustacea, Parastacidae): state of knowledge and conservation status. 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Rudolph, E. & A. Almeida. 2000. On the sexuality of South American Parastacidae (Crustacea, Decapoda). Invest. Rep. Dev., 37(3): 249-257 Rudolph, E. & K.A. Crandall. 2005. A new species of burrowing crayfish, Virilastacus rucapihuelensis (Crustacea: Decapoda: Parastacidae), from southern Chile. Proc. Biol. Soc. Wash., 118(4): 765-776. Rudolph, E. & K.A. Crandall. 2007. A new species of burrowing crayfish Virilastacus retamali (Decapoda: Parastacidae) from the southern Chilean peatland. J. Crustacean Biol., 27(3): 502-512. Received: 12 December 2014; Accepted: 15 July 2015 Rudolph, E. & K.A. Crandall. 2012. A new species of burrowing crayfish, Virilastacus jarai (Crustacea, Decapoda, Parastacidae) from central-southern Chile. Proc. Biol. Soc. Wash., 125(3): 258-275. Rudolph, E. & H. Rivas. 1988. Nuevo hallazgo de Samastacus araucanius (Faxon, 1914) (Decapoda, Parastacidae). Biota, 4: 73-78. Rudolph, E. & C. Rojas. 2003. 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Bogotá D.C., pp. 275-321. Lat. Am. J. Aquat. Res., 43(5): 819-827, 2015of the river prawn Macrobrachium americanum (Bate, 1868) The case DOI: 10.3856/vol43-issue5-fulltext-2 819 Review Conservation and aquaculture of native freshwater prawns: the case of the cauque river prawn Macrobrachium americanum (Bate, 1868) Marcelo García-Guerrero1, Rodolfo de los Santos Romero1 Fernando Vega-Villasante2 & Edilmar Cortes-Jacinto3 1 Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional-Instituto Politécnico Nacional (CIIDIR-IPN) Unidad Oaxaca, Santa Cruz Xoxocotlán, Oaxaca, México 2 Centro de Investigaciones Costeras, El Centro Universitario de la Costa Universidad de Guadalajara Puerto Vallarta, Jalisco 3 Centro de Investigaciones Biológicas del Noroeste (CIBNOR), La Paz, B.C.S., México Corresponding author: Marcelo U. García-Guerrero ([email protected]) ABSTRACT. Latin America has a high diversity of Macrobrachium prawns, some of them with commercial interest. Among them, the cauque river prawn Macrobrachium americanum is a large prawn of the western coast with commercial value due to its size and taste, but it has been extensively subjected to fishery exploitation, leading to population decline. Cultivation is an option for commercial production and conservation. Some research focused on domestication has been performed. Here, we revise the status of that research and discuss possibilities for sustainable freshwater prawn aquaculture in Mexico and elsewhere in Latin America. Keywords: Macrobrachium americanum, river prawn, production, management, aquaculture. Conservación y cultivo de especies nativas de langostinos: el caso del cauque Macrobrachium americanum (Bate, 1868) RESUMEN. América Latina tiene una gran diversidad de langostinos Macrobrachium, algunos de ellos con interés comercial. Entre ellos, el cauque, Macrobrachium americanum, una especie de la costa occidental de América que tiene valor comercial por su tamaño y sabor, que está ampliamente sujeto a explotación pesquera, que ha causado la disminución de sus poblaciones. El cultivo es una opción para su conservación y producción comercial. En el presente trabajo se revisó el estado de la investigación sobre la especie y se discuten sus posibilidades para la acuicultura sostenible en México y en otros países Latinoamericanos. Palabras clave: Macrobrachium americanum, langostino, producción, manejo, acuiculura. INTRODUCTION Freshwater Macrobrachium prawns are an important product both cultivated and extracted from rivers, mostly in Asia and Latin America (Grave et al., 2008). These prawns can be cultivated in simple facilities using low-cost methods (Valenti & New, 2000; Wahab et al., 2012). The less intensive farming operations and lower costs of freshwater prawn’s production compared to marine shrimp could make their culture an option for sustaining rural cultivation by small-scale farmers and local markets (Valenti & New, 2000; Kutty, 2005; Martínez-Córdova et al., 2009; Tidwell & D’Abramo, ______________________ Corresponding editor: Erich Rudolph 2010). There are some successful examples of intense production in several regions of the world (Valenti & New, 2000; Wahab et al., 2012; Almeida & MoraesValenti, 2012; Hongtuo et al., 2012; Nair & Salin, 2012; Na-Nakorn & Jintasataporn, 2012). In Asia, prawn farming is an important activity in expansion that plays an important role in alleviating poverty, generating employment and foreign currency (Wahab et al., 2012). Its expansion should continue if aquaculture is to satisfy the global demand for food products (Ross et al., 2008; Martínez-Córdova et al., 2009). However, today, expansion relies on a range of aquatic species representing only a small fraction of 820 Latin American Journal of Aquatic Research those with potential for aquaculture (Ross & Beveridge, 1995). This is particularly true in the case of Latin American Macrobrachium prawns, since only few species are fished or cultivated. This work discusses the potential for aquaculture of one of them, the cauque prawn (Macrobrachium americanum Bate, 1868; Fig. 1), provides information on the research status, and clarifies issues related to its exploitation. General panorama of prawn culture in Latin America Most Latin American countries are multicultural with many human societies still maintaining ancient traditions and having a very high biodiversity in their regions. In these countries, and Mexico in particular, ancient tradition related to the exploitation criteria of fisheries are still subjected to ancient methods, as they are part of strong traditional roots. Because of this, in addition to poverty issues, some of these fishery resources in the region are over-exploited and seem to be causing an adverse impact on particular populations. Freshwater prawns are not exempt of these effects. Most commercially available prawns come from informal fisheries since aquaculture is not practiced due to the lack of proper cultivation techniques for native species and the lack of sufficient research. Therefore, in Latin America this enterprise has failed to expand. This can be improved with the generation of research and proper management policies (Wahab et al., 2012; García-Guerrero et al., 2013). Why cultivate native species? In Mexico, the Comision Nacional para la Biodiversidad (CONABIO) identified four priorities related to conservation of live resources: a) protection and conservation, b) evaluation of biodiversity, c) planning and management of information, and d) diversification of resources use. The last statement involves cultivation of native species under sustainable aquaculture to minimize impacts caused by introduced species (Ross et al., 2008; Somoza & Ross, 2011). To be successful, farming should have a constant, readily available and affordable seed supply and, as far as possible, mostly of native species, including prawns. Native species are already adapted; there would be no heating expenses or costly facilities so production costs will be low. It is easy to avoid inbreeding problems by incorporating wild individuals (García-Guerrero & Apun-Molina, 2008; Hongtuo et al., 2012). Their cultivation could be an income source to local settlements and may provide relief to wild populations impacted by overexploitation and pollution (Schwantes et al., 2009). The economic and environmental requirements of each country would determine if cultivation is profitable and whether it will reach markets as a live, fresh-killed, processed, or frozen product. In contrast, exotic species often bring complications because they may not be adapted to exotic weather or water conditions and may not resist local diseases or incur in inbreeding or disease problems due to stocks degradation (Nair & Salin, 2012; Na-Nakorn & Jintasataporn, 2012). In addition, foreign species frequently introduce new pathogens or parasites (Ross et al., 2008). Since M. rosenbergii is exotic in Latin America and production of this species has declined in most of the continent, cultivation techniques for native species are being considered (Valenti & MoraesRiodades, 2004; Goda, 2008; Vega-Villasante et al., 2011). These studies have investigated Latin American prawn species with aquaculture potential. Good examples are known for M. amazonicum, M. tenellum and M. americanum The Macrobrachium americanum case This prawn is distributed along the Pacific slope of America between Baja California (Mexico) and Peru, as well as at Cocos and Galapagos Islands (Holthius, 1980). It is still present in most coastal areas where the rivers empty into lagoons and then to the ocean (Hernández et al., 2007). In the past, it was collected in areas far from coastal plains and it was widely present even in habitats where the amount of water is minimal during dry seasons, since it is able to overcome natural barriers. However, current human activities are contributing to a severe decrease of its populations. It has become scarcer every year, and the current status of its populations is unknown in most of its distribution range. In recent years, there has been increased interest in commercial farming of this species among producers and research groups. However, since there are no techniques for its culture its farming cannot start in its native region in the near future. General biology M. americanum is a species with a wide distribution potential either along the coast or into the continental waters including freshwater lakes, reservoirs and rivers in tropical and subtropical areas of western Mexico (Hernandez et al., 2007), as this species can reach large distances from the coast (more than 150 km). It could become a good biological index of ecological fitness, considering that domestic, agricultural, industrial and human wastes cause pollution at different scales and may easily kill larvae and juveniles that are very sensitive to small concentrations of pesticides, heavy metals (Piyan et al., 1985; Adhicari et al., 2007), and other anthropogenic pollutants (Shinn-Pyng et al., 2005). Females can spawn several times each year and The case of the river prawn Macrobrachium americanum (Bate, 1868) 821 b a Figure 1. Macrobrachium americanum prawns. a) Male, b) females. produce from some hundreds to almost three thousand eggs at each spawning (García-Guerrero & Hendrickx, 2009). Males may grow to about 29 cm in total length; the reproductive season occurs from May-September (García-Guerrero, 2009). In the regions where these prawns still exist, river conditions change intensely with the season (high water flow from May to October and low water flow from November to April). This phenomenon allows its reproduction, but increases its exposure to fishing (García-Guerrero et al., 2013). Its larval development involves fifteen larval stages that need salty water to survive (Holtschmit & Pfeiler, 1984; Yamasaki-Granados et al., 2013). As in most Macrobrachium species, wild females breed and spawn in freshwater but planktonic larvae must grow in brackish water. At juvenile stage, they become benthonic and start migrating into inland freshwater (Horne & Besser, 1977; Bauer, 2011). Based on previous studies, it is known that juveniles and adults are easy to feed in captivity, since they can consume all kinds of food with animal protein, mainly commercial shrimp pellets, fish, or squid meat (García-Guerrero & Apun-Molina, 2008). Few formal general biology studies have been done in this species. García-Guerrero et al., (2011) studied how O2 consumption was related to size and water temperature highlighting the negative effect of low oxygen concentrations. García-Guerrero & Hendrickx (2009) described embryonic development and García-Guerrero (2009, 2010) and determined variations in the proximate composition of eggs incubated at different temperatures. As in most decapod egg lipids are the main component for energy production and protein is the most abundant component (Holland, 1978). Fisheries and aquaculture The first studies in Mexico started in the 1970’s; but most are informal reports, anecdotal or with conflicting results (Mercado, 1959; Rodríguez de la Cruz, 1965, 1967; Arana-Magallón, 1974). Some formal studies focused on the potential of this species for cultivation have been done but still not enough to support cultivation beyond experimental assays. Some assays have been done in captivity by Ruiz et al. (1996) or Arana & Ortega (2004), finding fast growth of juveniles kept at low densities in tanks. García-Guerrero & Apun-Molina (2008) studied how density and shelters affect survival and growth of juveniles. Prawns kept at low density with a shelter grew faster and survived longer. The last authors stated that one disadvantage is that M. americanum is a territorial prawn and often aggressive, a behavior that is enhanced in large specimens. Cannibalism is not rare and recently molted specimens are the most likely preys. Larval cultivation of M. americanum has been performed up to the postlarval stage, although very poor survival has been 822 Latin American Journal of Aquatic Research attained (Arana-Magallón, 1974; Monaco, 1975; Holtschmit & Pfeiler, 1984; Díaz-Monge et al., 2001; Yamasaki-Granados et al., 2013). Monaco (1975) was the first to complete all stages of larval development (53 days at 29 ± 5°C) but with very poor survival. Yamasaki-Granados et al. (2013) state that recently hatched larvae (0 -72 h) can eat dead or slow nauplii; but apparently, they do not fulfill nutritional requirements and they seem to be hard to catch for such larvae. In addition, Díaz-Monge et al. (2001) reported that Artemia nauplii (24 h after hatching) are larger than M. americanum larvae; therefore, they are not suitable as food during early stages of development. YamasakiGranados et al. (2013) stated that the most important tasks for raising larvae include monitoring physical and chemical parameters of the water, breeding quality of the adults, and the use of high nutritional value and small in size live food, at least during the first half of development. To be effective, the food must be easy to be recognized and captured (Yamasaki-Granados et al., 2013). These last authors suggest that feeding with rotifers, which can tolerate brackish water, might be an option to overcome this problem, in addition to monitoring strictly temperature and salinity. In fact, Yamasaki-Granados et al. (2013) offer a table of salinities for cultivating the larvae of this prawn. Macrobrachium larvae can be cultivated with success in clear fresh water (Daniels et al., 1992), but including microalgae is also common. From previous research on cultivating prawn larvae, microalgae are recognized for their role in removing wastes and controlling light and dissolved O2 to benefit larvae (Lober & Zeng, 2009; Nunes et al., 2011; Yamasaki-Granados et al., 2013). Most recently, a study by Rojo-Cebreros et al. (2013) found that M. americanum is a good companion for tilapia fish and does not interfere with fish production. In relation to fisheries and because of their biological cycle, M. americanum prawns are exposed to year-round overfishing and there is an established local market during the whole year, since this prawn is fished for local consumption or sold to restaurants close to the fishing area. There are no records on its fisheries and most information available is informal and comes from fishermen. In most places, populations have severely declined or disappeared by overfishing, illegal fishing practices, pollution, alteration of habitat, and intensive collection of seed and juveniles since these are also cached, dried, and sold as food for ornamental fish (García-Guerrero et al., 2013). It is possible that this last practice hinders new population recruitment, but its real impact has not been examined yet. Main concerns that are poorly explored Studies on growth rate, survival, mortality, as well as the detailed effect of most environmental parameters that may affect this prawn either in the wild or under culture are lacking. However, the most urgent topic that should be addressed is the development of larval culture techniques. Production of larvae is perhaps the most critical issue before considering a species as a good candidate for commercial cultivation. Monaco (1975) was perhaps the first to obtain the larval development, but with poor survival. Ever since, few studies have addressed this particular issue. Highquality, laboratory-reared larvae are essential because successful and profitable production requires a constant supply of high quality juveniles for stocking, since no commercial activity can rely forever on wild larvae or postlarvae (New, 2005, 2009; New & Nair, 2012); hence, commercial production will eventually fail (Hongtuo et al., 2012; Yamasaki-Granados et al., 2013). Previous studies on larval development provide clues on larval management and feeding. Small larvae make the cultivation of M. americanum a difficult challenge. In recent studies, such as those of YamazakiGranados et al., 2013, the fry or seed supply was the most urgent focus, and this remains so. Production technology for larvae has to be standardized before constant mass production of juvenile prawns can be achieved. A well developed protocol for rearing juveniles in the hatchery or in the laboratory is necessary because gathering of wild juveniles does not guarantee constant, homogeneous, and high quality fry for stocking (Gopal, 2002). Success strongly depends on a ready supply of fry from hatcheries, which often is the hardest bottleneck to overcome and one of the main requisites before introducing any aquatic species to commercial cultivation. In spite of previous studies that have advanced on M. americanum larval development, there is no reliable technique for cultivating these larvae (Yamasaki-Granados et al., 2013). The use of antibiotics to prevent or control infectious diseases is also understudied, as well as that of immune stimulants and probiotics in food and water (Yamasaki-Granados et al., 2013). These products must be strictly controlled and supervised prior to their application, because they can produce unwanted effects during cultivation or on the environment (Gatesoupe, 1999; Yamasaki-Granados et al., 2013). Other considerations include the physiological consequences on prawns exposed to high levels of nitrogenous wastes (Romano & Zeng, 2013). Specific diets have not been prepared for this prawn, even though its nutritional requirements are similar to that of other prawns. Behavior and genetic studies that lead to selection of docile, resistant, and fast-growing lineages for aquaculture are always required (Nguyen et al., 2009), but none have been made in this species, and there are no studies about mono-sex cultivation. Social structure and behavioral studies are also necessary for The case of the river prawn Macrobrachium americanum (Bate, 1868) assessing maximum densities and combinations of sizes, sex, and age classes to control crowding. Hybridization with other Macrobrachium species, marketing potential of the species out of its native area, and tolerance to viral or bacterial infections are also unknown and required. In relation to reproduction issues, berried females availability is of major importance. They can be captured from the wild, but quality may be uncertain and stress can inhibit the females from attending the grooming behavior of their egg masses (García-Guerrero, 2009). In turn, this will lead to egg loss or infections causing low hatching rates (García-Guerrero, 2009). Because of this, research must include laboratory-produced berried females. Mating in captivity is easy in prawns, despite cannibalism of soft-shelled females but a maturation diet has not been developed yet for this species (GarcíaGuerrero & Apun-Molina, 2008). Other reproduction issues, such as all the environmental cues that influence gonadal activity (Ross & Beveridge, 1995) are still unknown. In relation to grow-out, for juveniles or adults under cultivation, balanced pelletized diets fundamental for fast grow-out have not been developed (D’Abramo et al., 1997). Since feeding is the most expensive cost of production, 40-60% of the total budget (Akiyama et al., 1992), studies on high quality but cheap balanced diets are required. Aggressiveness and cannibalism are other main concerns; crowding stresses prawns, making them aggressive and prone to infections, parasites, or loss of appetite (Ross & Beveridge, 1995). This is worse among aggressive prawns, and M. americanum is particularly aggressive, with well-developed territorial behavior, particularly adult males (García-Guerrero & Apun-Molina, 2008). During confinement, crowding, lack of shelters, and inappropriate food will cause larger prawns to seriously injure or kill smaller ones (García-Guerrero & Apun-Molina, 2008). During postmolt, mortality rates increase, even if appropriate food and shelters are provided. To minimize this problem, research on strains with docile behavior must be performed, or techniques focused to deal with this issue must be developed. Other issues must be studied once the basic features limiting cultivation technology are clarified. Specific cultivation techniques are required, such as the use of all-male stock, strains that grow fast, use of cheap local materials and products that are compatible with aquaculture. Legislation policies, management, weather, availability and quality of water, road conditions, electricity, communication, and distance from the final market are other secondary issues to determine the best areas for native prawns cultivation. In the case of marketing, the adoption of native species new to aquaculture into semi-intensive and intensive produc- 823 tion requires the generation of a vast body of biotechnical information. This enterprise should be executed after exploring marketing chances of success. In some situations, large-scale production for processing and shipping may not be economically competitive with products imported from Asia (Tidwell, 2012). Finally, outdoor cultivation studies are needed since growth and performance in ponds have neither been investigated. DISCUSSION Macrobrachium americanum’s potential for culture is still to be clarified, but most cultivation techniques and management strategies could be adapted from studies and manuals dedicated to other species, such as M. rosenbergii (New, 2005) or M. tenellum (VegaVillasante et al., 2011). These studies state that native prawns cultivation could be profitable in the corresponding region. It provides working opportunities to low-income farmers, with a product that can give them a high return. It has happened in countries such as Thailand or India, in which the culture of prawns is common as part of an extensive strategy that implies the use of wild berried females or wild juveniles stocked in cheap facilities and managed by families (Na-Nakorn & Jintasataporn, 2012). In China, breeding and larval rearing of M. nipponense and grow-out production has been developed (Hongtuo et al., 2012). Research institutions, in the late 1980’s, have also standardized in India mass production of prawn juveniles of M. malcolmsonii and M. gangeticum, under controlled culture schemes based on seed production technology (Nair & Salin, 2012). Since 1996, various research groups in Brazil have worked with the experimental culture of M. amazonicum (e.g., MoraesValenti & Valenti, 2007, 2009). After a hard starting with some unsuccessful results, basic technology is now available for all phases of production of this latter species. In addition, in Brazil, hatchery studies of M. carcinus provide promising results (Rocha et al., 2011). All those previous reports suggest that culture in a profitable scheme is possible with M. americanum, or with other native species if proper techniques are developed. Macrobrachium prawns culture may have additional advantages: they are a good option for aquaculture in tropical and semi-tropical regions because all phases of cultivation can be done year round since they can be stocked or harvested at any time, and two or three grow-out cycles per year are possible, with good profits (Tidwell, 2012). These prawns can be raised without access to saltwater or expensive coastal lands and they do not require much fishmeal in their 824 Latin American Journal of Aquatic Research diet (Tacon & Metian, 2008). For example, Tidwell (2012) evaluated freshwater prawns for sustainability on the following criteria: 1) Use of marine resources, 2) risk of escape of cultivated animals to the wild, 3) risk of disease and parasite transfer to wild populations, 4) risk of pollution and habitat degradation, and 5) effective management. Freshwater prawns were rated as “low environmental concern” in the five categories and were designated as a “best choice”. He stated that prawns were one of the most sustainable seafood choices available, which means their cultivation could be environmentally safe. In fact, Ross & Beveridge (1995) mentioned that aquaculture of native species could be suitable in economic, biotechnical, and environmental terms. Of course, research on native species needs to be analyzed through different criteria prior to commercial production. If properly cultivated, markets could include, in addition to human consumption, ornamental trade and bait (AlmeidaMarques & Moraes-Valenti, 2012). In addition, aquaculture may help to protect a species from overfishing by giving additional product supply (Bowles et al., 2000). For example, wild populations of M. rosenbergii were overfished in Thailand, and expansion of agriculture, habitat destruction, and water pollution led to a rapid populations decline (Na-Nakorn & Jintasataporn, 2012). However, since 1977, prawnbreeding technology for this species has improved; it has been cultivated in Thailand and thereafter annual production has increased and wild populations are recovering. Some areas of Mexico and shores all along western Latin America are appropriate for the cultivation of M. americanum, because they provide land areas with suitable water and weather conditions. In addition, juveniles produced from hatchery-reared larvae may help restore wild populations if proper measures to preserve genetic diversity are included in those programs. However, to introduce prawn farming as an option is hard not only because of lack of technologies, but also because in certain areas active fishing still provides easily catch product. This means that people of those regions will prefer to capture the prawns for consumption or for sale in the wild instead of working with culture techniques, which implies more investment and more work. To make it worse, most countries where M. americanum lives have no fishery policies, or have policies that are not enforced. Specific social and economic factors are also involved, depending on the region. Since biodiversity must be preserved, development of sustainable aquaculture requires consideration of an ecosystem approach (Ross et al., 2008, MartínezCórdova et al., 2009), which can be reached only working with native species in both culture and conservation programs. If possible, conservation programs including all research areas should be financed or executed based on restoration programs of this living resource. Since this task can be expensive and lengthy, it is important to focus on the most important factors (Ross et al., 2008). Ross & Beveridge (1995) considered the most important issues to be classified with these criteria: 1) Basic biology: natural habitat and habits, basic ecology and functional biology. 2) Environmental physiology: optimum temperature, salinity and photoperiod for growth and survival. 3) Closed reproductive cycle: developing the conditions for the whole cycle in captivity. 4) Nutrition: identification of natural feeding strategy and food items, feeds, and diets. 5) Growing systems: development of appropriate physical and farming systems for the species, its environment and the socio-economic status of the communities. Of these, issues 1 and 2 are mostly known for M. americanum, whereas issue 3 (part of larval studies) is suggested as urgent and having priority over issues 4 and 5. Knowledge-oriented research on nutritional requirements at the various stages of life and on behavioral aspects (social stratification in pond culture under high densities) must be carried out simultaneously with studies identified as having the highest priority. Additionally, cultivation of M. carcinus, a co-generic species with M. americanum but distributed on the Atlantic side of the tropical Americas, may prove feasible if equivalent attention is given. CONCLUSIONS Current knowledge of M. americanum cultivation is not sufficient to support cultivation beyond research purposes. The main problem that prevents cultivation of M. americanum, on a commercial scale, is the requirement of strict water quality control. Aggressiveness seems to be the other major obstacle. To consider the species as a commercial culture option is still not clear given its cannibalistic behavior and the lack of proper larval production technologies. Because of this, the case of M. americanum as a good option for sustainable aquaculture should first be aimed at conservation purposes since it needs special attention as a natural resource that has to be protected. Future studies must consider intraspecific variation in lifehistory traits of separate populations, which differ in physiological responses to salinity, egg size, feeding, The case of the river prawn Macrobrachium americanum (Bate, 1868) and other variable larval traits. Outdoor cultivation assays in ponds and managed with different techniques are required to appraise production possibilities and limitations. ACKNOWLEDGEMENTS M. García Guerrero thanks the Secretaría de Investigación y Posgrado and Comisión de Fomento de Actividades Académicas del Instituto Politécnico Nacional for their financial support. E. 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Experimental culture of the river prawn Macrobrachium americanum larvae (Bate, 1868), with emphasis on the stocking density effect on survival. Lat. Am. J. Aquat. Res., 41(4): 793-800. Lat. Am. J. Aquat. Res., 43(5): 828-835, 2015 DOI: 10.3856/vol43-issue5-fulltext-3 Nile tilapia in saline water Research Article Responses of Nile tilapia to different levels of water salinity Rafael Vieira de Azevedo1, Karen Figueiredo de Oliveira2, Fábio Flores-Lopes3 Eduardo Arruda Teixeira-Lanna4, Sylvia Sanae Takishita5 & Luís Gustavo Tavares-Braga5 1 Universidade Estadual do Norte Fluminense Darcy Ribeiro-CCTA-LZNA Campos dos Goytacazes, RJ, Brasil 2 Universidade Federal do Ceará, Fortaleza, CE, Brasil 3 Universidade Estadual de Santa Cruz-DCB-Ilhéus, BA, Brasil 4 Universidade Federal de Viçosa, Viçosa, MG, Brasil 5 Universidade Estadual de Santa Cruz-DCAA-Ilhéus, BA, Brasil Corresponding author: Rafael Vieira de Azevedo ([email protected]) ABSTRACT. A 45 day experiment was carried out to evaluate the effect of water salinity on the performance, haematological parameters and histological characteristics of the gills of the Nile tilapia, Oreochromis niloticus. The water salinity levels evaluated were: 0, 7, 14 and 21 g L-1. Nile tilapia specimens (1.62 ± 0.01 g), distributed into 20 fibreglass tanks (100 L) at a density of 15 fish per tank. There were no significant differences of the water salinity levels on daily feed intake; however, there were differences (P < 0.05) on the daily weight gain, feeding conversion rate and survival. The best results were observed for the water salinity levels of 0 and 7 g L-1. There were no differences (P > 0.05) between these levels. Regarding the haematological parameters, it was observed that the percentage of the haematocrits and the erythrocyte count were influenced (P < 0.05) by the water salinity level, which was not observed for the leukocyte count. The observed histopathological alterations were chloride cell hypertrophy, epithelial lifting, structure alteration, telangiectasia, primary lamellae cells aggregation, fusion and occurrence of aneurisms of different sizes in some secondary lamellae. Regarding the frequency of gills infection intensity, there were slight changes between the salinities of 0, 7 and 14 g L-1 and moderate changes at 21 g L-1. It is concluded that Nile tilapia can be reared in water salinities of up to 7 g L -1 without damage to the parameters evaluated in this work. Keywords: Oreochromis niloticus, haematology, histopathological alterations, aquaculture. Respuestas de la tilapia del Nilo a diferentes niveles de salinidad del agua RESUMEN. Se realizó un experimento de 45 días para evaluar el efecto de la salinidad sobre el crecimiento, parámetros hematológicos y características histológicas de las branquias de la tilapia del Nilo, Oreochromis niloticus. Los niveles de salinidad fueron: 0, 7, 14 y 21 g L-1. Los especímenes de tilapia del Nilo (1,62 ± 0,01 g) se distribuyeron en 20 estanques de fibra de vidrio (100 L) a una densidad de 15 peces por estanque. No hubo diferencias significativas en los niveles de salinidad sobre el consumo diario de alimento, pero hubo diferencias (P < 0,05) en la ganancia diaria de peso, conversión alimenticia y supervivencia. Los mejores resultados se observaron en los niveles de salinidad de 0 y 7 g L-1, sin diferencias (P > 0,05) entre ellos. En cuanto a los parámetros hematológicos, se observó que el porcentaje de hematocrito y número de eritrocitos fueron influenciados (P < 0,05) por el nivel de salinidad, que no se observó para el recuento de leucocitos. Las alteraciones histopatológicas observadas fueron: hipertrofia de las células de cloruro, elevación epitelial, cambio en la estructura, telangiectasia, agregación de las células primarias de las laminillas, fusión y aparición de algunos aneurismas de diferentes tamaños en laminillas secundarias. En cuanto a la frecuencia de la intensidad en la infección de las branquias, hubo ligeros cambios entre las salinidades de 0,7 y 14 g L-1 y cambios moderados a 21 g L-1. Se concluye que la tilapia del Nilo se puede cultivar en salinidades de hasta 7 g L-1 sin daño a los parámetros evaluados en este trabajo. Palabras clave: Oreochromis niloticus, hematología, cambios histopatológicos, acuicultura. __________________ Corresponding editor: Jesús Ponce 828 1 829 2 Latin American Journal of Aquatic Research INTRODUCTION MATERIALS AND METHODS In regions where fresh water is scarce, fish farming in brackish or salt water can provide a source of extra income (Dimaggio et al., 2009; Marengoni et al., 2010; Jesus et al., 2011). Tilapias can be reared in this type of environment provided gradual acclimatization procedures are adopted (Likongwe et al., 1996; Dominguez et al., 2004). The Nile tilapia (Oreochromis niloticus) is widely cultivated in fresh water; however, it tolerates certain levels of salinity, being considered as euryhaline. Despite its good adaptation capacity to salinity, it is less tolerant than other species of tilapia such as O. aureus and O. mossambicus (Kamal & Mair, 2005). The way that each species of fish responds to different salinity levels allows evaluation of the best place for its culture. Thus, several studies have evaluated the influence of this parameter on the performance of euryhaline fish (Likongwe et al., 1996; Boeuf & Payan, 2001; Tsuzuki et al., 2006; Luz et al., 2008; Riche & Williams, 2010). Besides the performance it is necessary to evaluate the effect of the salinity on fish health and organs (Árnason et al., 2013). The digestive tube and the gills that remain in direct contact with water and under physical and chemical environment changes may suffer morphologic alterations (Reis et al., 2009; Yuan et al., 2010). The gills are vital structures for the fish health, being involved in the processes of osmoregulation and nitrogen composites excretion, as well as being the main site for gaseous exchanges. Some functional changes such as the gill epithelium chloride cells and Na+-K+-ATPase activity were observed during the adaptation of tilapia to saline water (Güner et al., 2005). Thus, any damage to the filaments and branchial lamellae that can interfere with their function, will compromise the survival of these animals (Winkaler et al., 2001; Reis et al., 2009). Histopathological studies have been developed to evaluate the effects of contaminants on fish health in the environment and to help establish a causal relationship between exposure to toxic substances and various biological responses (Schwaiger et al., 1997). There is an increased incidence of diseases and pathological conditions in fish, as well as a variety of aetiologies. This increase is an indicator of environmental stress and provides a definitive biological endpoint of the history of exposure to a pollutant (Schwaiger et al., 1997). The aim of this study was to evaluate the performance, haematologic parameters and histological characteristic of Nile tilapia gills submitted to different levels of water salinity. The experiment was carried out at Ilhéus city, Bahia, Brazil (14º47’20”S, 39º02’58”W), during 45 days, with 300 juvenile (1.62 ± 0.01 g) Nile tilapia of Thai ancestry, sexually reversed, bred in fresh water, in a completely randomised design with four treatments (salinity levels) and five repetitions. The fish were distributed into 20 cylindrical fibreglass tanks, with a useful volume of 100 L, at a density of 15 fishes per tank. The tanks were placed in a closed recirculation system in four groups, used with biological filters through four water pumps, one for each salinity level. Each tank received individual aeration by means of porous stones fed by a 1 hp air blower. During the fish acclimatization period, the salinity was raised by 2 g L-1 day-1 with seawater (35 g L-1) replacing the fresh water from the experimental tanks. The water salinity levels evaluated were 0, 7, 14 and 21 g L-1. The fish were fed an extruded commercial feed with 360 g kg-1 crude protein, 70 g kg-1 ether extract, 130 g kg-1 moisture, 120 g kg-1 mineral matter, 20 g kg-1 calcium, 10 g kg-1 phosphorus and 250 mg vitamin C (guarantee levels). The feed was ground in a knife mill with 1.0 mm sieve and supplied ad libitum four times a day (07:00 am, 10:00 am, 01:00 pm and 04:00 pm). Water-quality parameters were measured daily. Dissolved oxygen, pH and temperature were measured through multi-parameter devices (YSI model 55-12FT, YSI Corporation, Owings Mills, MA, USA); salinity was measured with a refractometer (Atago S/Mill-E, Atago Co. Ltd., Tokio, Japan). At the beginning of the experiment and after 45 days, all fish were weighed. The individual daily consumption of feed was obtained by the ratio between the total consumption of feed of each fish and the experimental period. The daily weight gain was calculated by difference between the final and initial weights of each fish relative to the experimental period. The feed conversion rate was calculated by the ratio between the feed consumed and the weight gain at the end of the experiment. The survival was calculated through the ratio between dead and live individuals. At the end of the experiment, after biometrics measurements, four specimens were randomly selected from each repetition for cardiac puncture blood collection (after anaesthesia with benzocaine 0.1 g L-1) with a syringe containing 10% EDTA (Ethylenediamine tetraacetic acid). The erythrocyte and leukocyte counts were determined by dilution and counting in a haemocytometer. The percentage of 830 3 Nile tilapia in saline water haematocrits was carried out according to the microhematocrit method. One specimen (tilapia) of each treatment was sacrificed (benzocaine) for the histopathological examination of the gills. The material was fixed in 10% formalin for a week and then preserved in 70% alcohol. The gills of the most external gill arches were removed, always on the right-hand side of the fish. The gills were decalcified with EDTA for a period ranging from three days to a week. The specimens were prepared for histological analysis using an ethanol routine dehydration technique, then impregnated and embedded in paraffin. Sections of 5-7 m were made with a microtome. The sections were stained with haematoxylin and eosin (H&E) for visualisation of the affected tissues and organs. For a better understanding of the results, the histopathological alterations were classified as scores of 0 to 3, where 0 = no alteration, 1 = slight alteration, 2 = moderate alteration, and 3 = severe alteration. The definitions slight, moderate and severe were modified from Poleksic & Mitrovic-Tutundzic (1994) and are characterised as follows: slight alteration (1) involves changes that do not damage gill tissues so that the restructuration and recovery of normal gill function can occur with improvement of the environmental conditions. These changes are limited to small parts of the gills or some filaments; for example, slight alteration of the epithelium of the primary lamella. Moderate alteration (2) involves more severe changes that lead to effects in tissues associated with the functioning of the organ. These lesions are reparable, but if wide areas of the gills are affected or maintained in situations of chronic pollution, they can lead to severe alterations, on practically the whole surface of the gills, for example, the epithelial lifting of secondary lamella. In cases of severe alteration (3), the recovery of the gill structure is not possible, even with improvement in water quality or no further exposure to a toxic stimulus, for example, aneurysms. This scale was used to determine the mean values of alteration intensities for each treatment. The presence of histopathological alterations for gills was determined semi-quantitatively by the degree of tissue alteration (Histopathological Alterations Index - HAI), based on the severity of the injuries. In the determination of the HAI (modified from Poleksic & Mitrovic-Tutundzic, 1994), the alterations in each organ were classified in progressive stages of tissue damage (Table 1). The HAI value was calculated for each animal using the following formula: HAI = (1X SI) + (10X SII) + (100X SIII), where I, II and III correspond to the number of stages of alterations 1, 2 and 3; and S represents the sum of the number of alterations for each particular stage. HAI values between 0 and 10 indicate normal functioning of the organ; values 11 to 20 indicate slight damage to the organ; 21 to 50 indicate moderate alterations in the organ; values 50 to 100 indicate severe lesions; and values >100 indicate irreparable lesions of the organ (Poleksic & Mitrovic-Tutundzic, 1994). Some cases were selected and photographed with the use of a photomicroscope. Data were analysed by ANOVA followed by Tukey’s test (P < 0.05). To set the best water salinity level was carried out the Regression analysis (P < 0.05). The non-parametric Mann-Whitney test for independent samples with P < 0.05 was used for comparison of anomaly intensity means between five specimens of each treatment. The differences between treatments were tested using non-parametric ANOVA. The degree of significance was 95%. Statistical analyses were carried out using the software R. RESULTS The addition of seawater to the fresh water did not change the parameters of water quality, dissolved oxygen, temperature and pH, monitored during the experimental period, which had been similar (P > 0.05) between the treatments and remained inside the acceptable range for fish breeding (Table 2). There was no effect (P > 0.05) of salinity levels on daily feed intake, obtaining an average 0.54 g day-1. The salinity levels affected the other variables of fish performance (Table 3). Water salinity levels had significant effect on the daily weight gain (P = 0.0267), feed conversion rate (P = 0.0072) and survival (P = 0.0005) of Nile tilapia. A significant reduction of these parameters was observed at 14 and 21 g L-1 of water salinity by Tukey’s test analysis. Regression analysis showed a quadratic behavior with better values for, respectively, daily weight gain, feed conversion rate and survival of 5.62, 2.08 and 4.19 g L-1 of water salinity (Figs. 1, 3). Regarding the haematological parameters evaluated, it was observed that the haematocrit (P = 0.0001) and the erythrocyte count (P = 0.0040) were influenced by the water salinity level with higher values in 0 and 7 g L-1; however, the leukocyte count did not change (P = 0.5376) regardless of the water salinity level (Table 4). Regression analysis showed a quadratic behavior with better values for, respectively, haematocrit and erythrocyte count of 0.92 and 2.39 g L-1 of water salinity (Figs. 4, 5). 4831 Latin American Journal of Aquatic Research Table 1. List of histopathologic alterations observed in the gills of Oreochromis niloticus. I, II and II – Severity stages of alterations. Stage I II III Histopathologic alterations in the gills Hypertrophy and hyperplasia of gill epithelium Sanguineous congestion Dilation of marginal vascular channels Lifting of respiratory epithelium Fusion and disorganisation of secondary gill lamellae Shortening of secondary lamellae Leukocyte infiltration of gill epithelium Aggregation of cells of the primary lamella Haemorrhage and rupture of lamellar epithelium Hypertrophy and hyperplasia of mucous cells Empty mucous cells or their disappearance Hypertrophy and hyperplasia of chloride cells Lamellar aneurism Necrosis and cell degeneration Lamellar telangiectasis Table 2. Mean values and standard deviation of the physical and chemical parameters of the water of the experimental tanks, in a accordance with the treatment. Parameter Dissolved oxygen (mg L-1) Temperature (ºC) pH Salinity (g L-1) 0 4.75 ± 0.63 28.19 ± 1.25 7.06 ± 0.71 0.02 ± 0.01 Salinity (g L-1) 7 14 4.58 ± 0.13 4.51 ± 0.48 28.33 ± 1.10 28.27 ± 0.96 7.16 ± 0.11 7.14 ± 0.13 7.06 ± 0.71 13.75 ± 1.17 21 4.32 ± 0.45 28.31 ± 0.99 7.14 ±0.14 20.73 ± 1.59 Table 3. Performance and survival of Nile tilapia cultured in different salinity levels. *Significant, NS: not significant. Means followed by different letters in the lines differ by Tukey’s test (P < 0.05). Variable Initial weight (g) Daily feed intake (g day-1) Daily weight gain (g day-1) Feed conversion (g g-1) Survival (%) 0 1.60 ± 0.21a 0.52 ± 0.01a 0.46 ± 0.01a 1.15 ± 0.10a 95.00 ± 5.53a Salinity (g L-1) 7 14 1.63 ± 0.19a 1.61 ± 0.15a 0.57 ± 0.07a 0.52 ± 0.07a a 0.52 ± 0.01 0.41 ± 0.02b a 1.10 ± 0.02 1.28 ± 0.05b a 97.33 ± 3.65 83.99 ± 3.64b Regarding the histological analysis, Nile tilapia gills have the same pattern as in other teleosts. The filament is covered by a stratified epithelium in the interlamellar region in which there are epithelial cells, melanocytes, lymphocytes, macrophages, granulocytes and eosinophils, as well as chloride cells. The structure of the gill arch and gill filaments shows mucosal cells. The secondary lamella is covered by a squamous epithelium that generally shows a thickness of one or two cell layers. Below the epithelium there are lamellar blood spaces that are bordered by pillar cells, which have a contractile function. In the outermost region of the 21 1.62 ± 0.22a 0.53 ± 0.06a 0.42 ± 0.02b 1.29 ± 0.05b 80.83 ± 9.25b F 2.54NS 2.79NS 3.64* 8.24* 15.87* secondary lamella, there is a blood vessel that has an internal covering of endothelium (Fig. 6). The histopathological alterations observed in Oreochromis niloticus were chloride cell hypertrophy, epithelial lifting, structure alteration, telangiectasia, aggregation of cells of primary lamellae, fusion and occurrence of various sizes aneurysms in some secondary lamellae. Slight alterations were observed in the first treatment, such as epithelial lifting and fusion of secondary lamellae and severe alterations such as telan- Nile tilapia in saline water Figure 1. Effect of water salinity levels on the daily weight gain of Nile tilapia. 8325 Figure 3. Effect of water salinity levels on the survival of Nile tilapia. respectively), indicating that individuals present irreparable injury in the body and that even if water conditions improve, the structure of the body cannot be recovered (Table 5). The high average values is due to the presence of aneurysms, which are regarded as a serious injury, in almost all the individuals. DISCUSSION Figure 2. Effect of water salinity levels on feed conversion rate of Nile tilapia. giectasia in a few secondary lamellae. In salinity of 7 g L-1, slight alterations were observed such as epithelial lifting, fusion of secondary lamellae, aggregation of cells in the primary lamella and severe alterations such as telangiectasia and aneurysms in a few secondary lamellae. In salinity of 14 g L-1 slight alterations were observed such as bifurcation of secondary lamellae, fusion of secondary lamellae, epithelial lifting and severe alterations such as telangiectasia and aneurysms with frequency higher than in previous treatments. In salinity of 21 g L-1 a greater number of slight alterations was observed, which were epithelial lifting, fusion of secondary lamellae, change in the structure of secondary lamellae, chloride cell hypertrophy, and aggregation of cells of the primary lamella. Telangiectasia and aneurysms were observed among the severe alterations. Only slight alterations (1) were found in salinities of 0, 7 and 14 g L-1 when we analysed the gills’ frequency of infection intensity; in salinity of 21 g L -1 we observed a high frequency of individuals with moderate alterations (2) (Fig. 7). The results of the Histopathological Alteration Index (HAI) showed that in all treatments there were averages above 100 (102.0, 136.7, 137.7 and 172.3, The fish survival and growth can be influenced by the water quality (Likongwe et al., 1996). The relationship between salinity and fish growth seems to be complex, because studies with different species have presented varied results. Similar results were reported by Likongwe et al. (1996), who evaluated different salinity levels (0, 8, 12 and 16 g L-1) and water temperature (24, 28 and 32ºC) on the performance of juvenile Nile tilapia (4.6 to 4.8 g), observing a better performance in the highest temperatures evaluated, and a decrease from 8 g L-1 of water salinity. They also observed that the combination between the salinity of 8 g L-1 and water temperature of 32ºC resulted in better feed conversion rate. The best performance of the fish cultivated in the lower water-salinity levels in this experiment can be related to the energy cost for the ionic regulation, which is lower when the fish are kept in an isotonic environment, where ionic gradients between the blood and the water are minimum, and this energy economy can be directed towards growth (Boeuf & Payan, 2001). Besides osmoregulation, the effect of water salinity on the performance of fish can be explained by its action upon digestive enzymes, where the exposure to different salinities modifies the water ingestion, altering the salinity of the intestinal content and affecting the activity of digestive enzymes (Moutou et al., 2004). This process can explain the worsening in the alimentary conversion and consequent worsening of the weight gain of tilapias in the highest salinities in this experiment. 6833 Latin American Journal of Aquatic Research Table 4. Hematological variables to Nile tilapia cultivated in different salinity levels. *Significant, NS: not significant. Means followed by different letters in the lines differ by Tukey’s test (P < 0.05). Variable Haematocrit (%) Erythrocyte (x106 µL-1) Leukocyte (x103 µL-1) Salinity (g L-1) 0 25.4 ± 1.82a 1.58 ± 0.20a 23.01 ± 8.63a 7 27.6 ± 1.72a 1.86 ± 0.29a 23.05 ± 10.21a 14 18.4 ± 1.34b 1.08 ± 0.15b 23.31 ± 7.04a 21 16.8 ± 3.11b 1.08 ± 0.15b 19.75 ± 3.11a F 16.95* 7.77* 0.42NS Figure 4. Effect of water salinity levels on the haematocrit of Nile tilapia. Figure 6. Histological sections of gills of Oreochromis niloticus specimens: a) Normal gill (1: primary lamella, 2: secondary lamella, H&E, 400x), b-d) Histopathological alterations. b and d) H&E 400x; c) H&E, 1000x; 3: telangiectasis; 4: aggregation of cells of the primary lamella; 5: hypertrophy of chloride cells; 6: intensive epithelial lifting; 7: lamellar aneurysms. Figure 5. Water salinity levels effect of upon erythrocyte count of Nile tilapia. In this study, although the leukocyte values were not influenced (P > 0.05) by the different water salinity levels, there was a decrease of these values with increased salinity. This small difference between the compared values may be due to the high standard deviation. The haematocrit and erythrocyte count found in this study for the water salinity levels of 0 and 7 g L-1 were similar to the reference erythrogram values for Nile tilapia observed by Barros et al. (2009) and Teixeira et al. (2012). However, for the salinity levels of 14 and 21 g L-1, the values were lower than those found by these authors. The study of the haematological analyses allows understanding of the influence of the nutritional and environmental conditions on fish health (Ranzani- Paiva & Silva-Souza, 2004). In this study, for the water salinity levels of 0 and 7 g L-1, the blood parameters for haematocrit percentage and erythrocyte and leukocyte counts were adequate and indicated healthy fish as described by Barros et al. (2009). In contrast, the amounts obtained for the water salinity levels of 14 and 21 g L-1 were inadequate, suggesting that the fish may have suffered stress caused by the higher levels of water salinity. The high variation between the haematological parameters has also been shown by Ranzani-Paiva & Silva-Souza (2004), who attributed this variation to internal and external factors. According to Aird (2000), the anaemia may be characterised when two or more blood parameters are below the normal average for the species. In this case, the haematocrit and erythrocyte values support this hypothesis for the water salinity levels of 14 and 21 g L-1. The increased water salinity probably damaged the erythropoiesis of juvenile tilapia, which could not main- 834 7 Nile tilapia in saline water Table 5. Results of histopathological alteration index (HAI) in each treatment. N: Number of individuals, M: means, SD: standard deviation. Salinity (g L-1) 0 7 14 21 Figure 7. Frequency of intensity of anomalies in gills, per treatment, during the study period. 0: without alterations, 1: slight alteration, 2: moderate alteration, and 3: severe alteration. tain the minimum necessary production of erythrocytes for health maintenance (Barros et al., 2009). Likewise, the number of leukocytes, which are part of the organism’s defence system, may have been reduced (although not presenting a significant difference) as a result of the stress caused by the highest salinity levels evaluated, damaging the organism’s defence functions, which can explain the highest mortality rates with the highest water salinity levels. Only a few micrometres separate the blood from the water in the gills (Yada et al., 2012), which not only facilitates the exchange of gases, but also allows the gill tissue to be exposed to variations in the environment. Consequently, the presence of toxic substances in the environment causes alterations in the vital functions carried out by the gills and alterations in the morphologic structure of these organs (Poleksic & Mitrovic-Tutundzic, 1994). Thus, the histopathological analysis of fish gills has been used as a tool that is extremely important in the evaluation of the quality of aquatic ecosystems. Physical and chemical changes in this ecosystem are rapidly reflected as quantifiable physiologic measurements in the fish. In general, reactions of the fish gills due to an irritant include inflammation, hyperplasia, lamellar fusion, excessive production of mucus, epithelial lifting, flattening of the secondary lamella and formation of aneurysms. Inflammation, hyperplasia, secretion of mucus and aneurysms were also observed in O. niloticus, demonstrating that the gills of these individuals had been affected by the action of various stressors (Schwaiger et al., 1997). Because of the epithelial lifting, there is an increase in the distance between the water and blood, impairing oxygen uptake. However, in these conditions, the fish increase their rate of respiration by compensating for the low entrance of oxygen (Emmanouil et al., 2008). N 5 5 5 5 Means of HAI SD 102.0 54.4 136.7 45.3 137.7 44.5 172.3 0.9 According to Winkaler et al. (2001), these types of histopathological lesions indicate that the fish respond to the effects of toxic agents present in the water. In this study, the high frequency of occurrence of telangiectasia and aneurysms may be associated with salinity. Stentiford et al. (2003) found an increased frequency of aneurysms in specimens captured in contaminated areas. These authors observed that these lesions, which cause disturbances in blood flow in the fish gills, can be associated with the presence of irritants in the water. Therefore, the presence of these alterations can be useful biomarkers for certain substances. Histopathological alterations such as lamellar aneurysm and epithelial lifting were also observed by Winkaler et al. (2001) in different species. The results of this study demonstrate that Nile tilapia can be raised in environments with moderate levels of water salinity. 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Histological and physiological biomarkers to assess fish health in Londrina streams, state of Paraná. Acta Sci., 23(2): 507-514. Yada, T., S.D. Mccormick & S. Hyodo. 2012. Effects of environmental salinity, biopsy, and GH and IGF-I administration on the expression of immune and osmoregulatory genes in the gills of Atlantic salmon (Salmo salar). Aquaculture, 362-363(1): 177-183. Yuan, X., H. Yang, L. Wang, Y. Zhou & H.R. Gabr. 2010. Effects of salinity on energy budget in pond-cultured sea cucumber Apostichopus japonicus (Selenka) (Echinodermata: Holothuroidea). Aquaculture, 306(2): 348-351. Lat. Am. J. Aquat. Res., 43(5): 836-844,Effects 2015 of protein and carbohydrate on juveniles of Samastacus spinifrons DOI: 10.3856/vol43-issue5-fulltext-4 8361 Research Article Effects of different protein and carbohydrate contents on growth and survival of juveniles of southern Chilean freshwater crayfish, Samastacus spinifrons Italo Salgado-Leu1 & Albert G.J. Tacon2 Escuela de Acuicultura, Universidad Católica de Temuco. Rudecindo Ortega 02950, Temuco, Chile 2 Aquatic Farms Ltd., 49-139 Kamehameha Hwy, Kaneohe, HI96744, USA 1 Corresponding author: Italo Salgado Leu ( [email protected]) ABSTRACT. In cultivated aquatic organisms nutritional requirements are critical, not only for their impact on production techniques, but also, for their high incidence on production costs. There is limited knowledge on some species such as the southern Chilean freshwater crayfish, Samastacus spinifrons. In order to generate practical knowledge, a study was carried out to determine protein and carbohydrate content requirements. These factors were evaluated upon their effects on growth and survival of juveniles. For this purpose, individual weight, biomass gain, survival, and feed conversion parameters were measured. The assay was carried out in 42 days, It was conducted in a flow through system, using 21 plastic tanks of 10.6 L capacity. Each tank was seeded with 20 juveniles weighing 50 mg average each. A 3x2 factorial design was proposed with three protein contents (20, 30, 40%) and two carbohydrate contents (low: from 16.3 to 23.5% and high: from 34.6 to 35.8%). Six treatments and three replicates were performed. Individuals were fed on apparent satiation once a day. The diets formulated with 30% of protein and the two carbohydrate contents resulted in higher biomass increases, food conversion efficiencies over 26%, and specific growth rate of 0.78%, all displaying significant differences. Survival showed highly significant differences; in all diets were superior to 60%, however the diets with 30% of protein surpassed 90%. Keywords: Samastacus spinifrons, Crustacea, diets, protein-carbohydrate content, southern Chile. Efecto de diferentes niveles de proteína y carbohidratos sobre el crecimiento y sobrevivencia de juveniles del camarón de río del sur de Chile, Samastacus spinifrons RESUMEN. En organismos cultivados, los requerimientos nutricionales, resultan ser de suma importancia, no sólo por sus impactos en las técnicas de producción, sino también por su alta incidencia en los costos de producción. Este conocimiento es escaso en algunas especies como el camarón de río del sur de Chile, Samastacus spinifrons. A fin de generar un conocimiento práctico, se definieron los requerimientos de proteínas y de carbohidratos y se evaluaron sus efectos en el crecimiento y supervivencia de juveniles. Para esto, se midió peso individual, biomasa ganada, supervivencia y parámetros de conversión alimenticia. La parte experimental se realizó en un sistema de flujo abierto, conformado por 21 estanques de plástico con capacidades de 10,6 L, durante un periodo de 42 días. Se sembraron 20 individuos en cada estanque con pesos individuales de 50 mg en promedio cada uno. Se propuso un diseño factorial de 3x2 con tres niveles de proteína (20, 30 y 40%) y dos niveles de carbohidrato (bajo: 16,3 a 23,5% y alto: 34,6 a 35,8%). Se desarrollaron seis tratamientos con tres réplicas. Los individuos fueron alimentados a aparente saciedad, una vez al día. Las dietas con 30% de contenido proteínico con ambos niveles de carbohidratos ofrecieron incrementos de biomasa más altos, eficiencia de conversión alimenticia de 26% y tasa de crecimiento específico de 0,78%, todos ellos con diferencias significativas. La supervivencia presentó diferencias altamente significativas, si bien en todas las dietas fue superior al 60%, en las dietas con 30% de proteína supeó el 90%. Palabras clave: Samastacus spinifrons, Crustacea, dietas, niveles de proteínas y carbohidratos, sur de Chile. INTRODUCTION In the Astacidea field, several investigations on the cultivation of species have been performed, the Astacus ____________________ Corresponding editor: Mauricio Laterça and Austropotamobius in Europe, the Pacifastacus and Procambarus in North America, and the Cherax in Australia and South America (Celada et al., 1989; Ackefors et al., 1992; Webster et al., 1994; Jones, 1995; Ghiasvand et al., 2012; Xu et al., 2013). 2837 Latin American Journal of Aquatic Research Chile is a country located in South America, sustaining one of the most intensive fish farming activities for salmon, and sharing with Norway the first places in salmon production (FAO, 2014). However, the country’s intention is to diversify its aquaculture activities towards other potential species. Thus, Chile has implemented a National Aquaculture Policy to fulfill this purpose. Among the species, with possibilities to diversify the aquaculture, four species of the family Parastacidae reported along the Chilean coast are identified. However, most of the attention has been drawn towards the southern Chilean crawfish, Samastacus spinifrons, characterized by its good flavor and corporal size. The existing data on S. spinifrons, is mostly on its biology (Rudolph, 2002, 2015) and on some preliminary production tests done by Fundación Chile (Augsburger, 2003). However, in order to reach an effective development of the cultured species, it is necessary to have the base of seed production to assure the following grow-out phase. A fundamental aspect to succeed with its culture is the knowledge of juvenile nutritional requirements (Saoud et al., 2012), from weaning to juvenile size, that allow them to be placed under growing techniques. S. spinifrons passes the larval period in the abdominal cavity of gravid females (Rudolph, 2002) as any other astacids (Jones, 1995) which is an advantage for cultural purposes. Protein will then be relevant to consider in for further stages, to generate information on their protein requirements. Probably in a similar way done for most practical shrimp diets based upon cost and growth response (Lim, 1997). Both elements are imperative to evaluate different protein dietary content and determine the optimal content to sustain maximum growth. Taking into account the above-mentioned considerations, and the nutritional importance in culturing production of aquatic species for juvenile S. spinifrons, the present study was performed to establish a protein content requirement, by setting up a factorial design (3x2) formulating diets with three different protein contents (20, 30 and 40%) and two carbohydrate contents (low and high). MATERIALS AND METHODS The assay was carried out at Universidad Católica de Temuco (UC Temuco) Aquaculture Department, and was conducted in a flow through system, using 21 rectangular plastic tanks of 10.6 L capacity with an open flow (Q) of 0.12 L min-1 with constant aeration. PVC pipe pieces of 1.27 cm diameter and length of 4 cm were placed into each tank as shelter elements. Twenty juveniles weighing 49.6 ± 4.82 mg were seeded into each tank and were maintained for 42 days. Six diets were formulated to contain three contents of protein and two relative carbohydrate contents. A 3×2 factorial design with three replicates per dietary treatment was used in this study. Diets were prepared with the ingredients indicated in Table 1. The feed formulation model was developed using an Excel software (Table 2) with the following factors and contents: three protein contents (20, 30 and 40%) and two carbohydrate contents (low: from 16.3 to 23.5% referred to as: “C low” and high: from 34.6 to 35.8%, named as: “C high”) (Table 3). Selected ingredients and prepared diets were analyzed at UC Temuco Aquaculture Department in the Nutritional Laboratory according to the Official Methods of Analysis (AOAC, 1998). For the food preparation, each grounded ingredient was passed through a 300 µm mesh size and weighed the recommended quantity according to the formulation. In the manufacture process of the experimental diets, dry ingredients, except wheat flour, were mixed during 40 min in a blender machine (Kitchen aid; model K5SS). Separately, wheat flour was hydrated and put under a cooking process for 15 min. The resulting gelatinized wheat was mixed with fish oil and a capsule of vitamin E (antioxidant). Finally, the oily gelatinized wheat was combined with other dry ingredients for further 45 min. A meat grinder machine RCA (1 HP) with a matrix screen of 1.5 mm orifices was used to make different pelleted diets. The pellets were dried during 36 h at 55°C and later stored under freezing conditions (-20ºC). The juveniles were fed once per day at same time and mortality was checked and removed. The amount of food provided in each diet was registered on a daily basis. The uneaten diet in each tank was removed every day before feeding with a suction tube and stored in separate recipients into the refrigerator, depending of the experimental unit. After seven days, the removed uneaten diet was defrosted and dried in a 55°C oven for 24 h. The removed uneaten diet was discounted from the food placed into each tank and then, the actual food consumption for each tank was determined. Individual weight was measured at the beginning and at the end of the experiment (day 42) with a Sartorious analytical scale (capacity of 217 g and precision of 0.0001 g). Growth parameters were calculated and evaluated: individual weight gain (mg), specific growth rate (SGR), biomass gain (%), and survival (%). Nutritional parameters were also evaluated: feed conversion ratio and feed conversion efficiency (%), according to De la Higuera (1987) and Bureau et al. (2002). 8383 Effects of protein and carbohydrate on juveniles of Samastacus spinifrons Table 1. Proximate composition (%) of ingredients used in the formulation of diets tested on Samastacus spinifrons juveniles. Crude protein Ether extract Nitrogen-free extract Crude fiber Ingredients Fishmeal 73.59 7.25 1.35 1.19 Blood meal 87.53 1.71 2.59 1.92 Lupine meal 49.23 10.59 32.73 3.64 Lupine fiber meal 3.00 0.70 35.40 50.10 Carrot meal 12.56 2.51 55.23 13.74 Kelp meal 14.89 0.65 56.27 5.75 Wheat meal 11.27 1.93 83.36 2.30 Fish oil 100.00 Ash 16.62 6.25 3.81 2.60 15.96 22.44 1.14 Water 10.34 5.44 9.33 8.20 16.19 23.25 12.65 Table 2. Composition of experimental diets (%), according to ingredient participation. CP: crude protein, C: carbohydrate. Diets Ingredients 20%CP 20%CP C low C high Fish meal 24.8 2.1 Blood meal 1.0 2.0 Lupine meal 1.0 30.4 Lupine fiber meal 38.0 29.6 Carrot meal 5.0 5.0 Kelp meal 4.0 4.0 Wheat meal 2.5 15.6 Fish oil 7.8 6.3 Vitamins and minerals 1.5 1.5 Inorganic 14.4 3.5 Normality, homoscedasticity and independence were tested previously on recollected data, then a twoway analysis of variance was applied to determine its interactions. If significant (P < 0.05) differences were found, Tukey tests were used to compare averages between treatments. In each carbohydrate content, protein diet contents were compared by one-way ANOVA followed by a Tukey test. All values were calculated using Minitab statistical software (version 16.1, Minitab State College, PA, USA). Electric heaters kept the water temperature at approximately 18ºC. Dissolved oxygen (5.2 ± 0.6 and pH (7.0 ± 0.2) were measured with YSI-85 equipment. RESULTS Growth parameters such as individual weight gain (mg), SGR, biomass gain (%), food conversion rate (FCR), food conversion efficiency (FCE-%) and survival rate (%) of S. spinifrons juveniles are shown in Table 4. No significant interactions (P > 0.05) were found for individual weight gain and SGR. Biomass gain and FCR were significantly high for diets with 30%CP 30%CP C low C high 23.0 4.0 14.0 3.9 2.1 47.4 36.0 14.5 5.0 5.0 4.0 4.0 2.6 16.0 4.7 1.6 1.5 1.5 7.1 2.1 40%CP 40%CP C low C high 23.1 1.0 23.0 21.0 8.0 41.5 30.5 0.1 5.0 5.0 4.0 4.0 2.6 24.8 2.0 0.1 1.5 1.5 0.3 1.0 30% CP followed by 20% CP in interactions with low carbohydrate concentration contents. 30% CP+C low exhibited significantly higher FCE than other combinations. Survival for 30% CP + C low was the highest value (95%) however, differences only showed to be significant with 20% CP + C low. Protein content behavior under relative low carbohydrate content, offered better growth values than relative high carbohydrate content, not only in biomass gain (Fig. 1), but also in all the other parameters measured (individual weight gain, SGR, FCR, and FCE). Survival had a punctual significant exception in 20% CP with C low (62.5%). Highest values were significantly recorded at 30% CP for biomass gain, FCR and FCE. For SGR, FCR and FCE, 30% CP was significantly different to 20% and 40% CP. For survival at C low significant differences were presented in all CP content, being 30% CP the best. At relative high carbohydrate content, there were no significant differences between protein contents. Curves for relative high carbohydrate content showed more flattened tendency form than relative low carbohydrate content. 4839 Latin American Journal of Aquatic Research Table 3. Proximate composition analysis (%) of experimental diets. CP: crude protein, C: carbohydrate. Diets Crude protein Ether extract Nitrogen-free extract Crude fiber Ash Water 20% CP+C low 20% CP+C high 30% CP+C low 30% CP+C high 40% CP+C low 40% CP+C high 20.8 19.4 30.5 29.5 41.1 41.0 6.7 6.8 9.5 4.4 5.3 2.3 23.5 34.6 22.2 34.9 16.3 35.8 21.4 18.9 19.8 11.2 18.6 3.5 23.6 7.3 14.2 6.3 7.4 5.5 4.1 13.0 3.8 13.7 11.4 11.9 Table 4. Samastacus spinifrons. Growth and survival of juveniles after 42 days of feeding on experimental diets containing different crude protein (20%, 30%, 40%), and relative carbohydrate contents (C high, C low) in diets. Different letters indicate significant difference (P < 0.05). SGR: specific growth rate, FCR: food conversion rate, FCE: food conversion efficiency. 20% Parameters Individual weight gain (mg) SGR Biomass gain (%) FCR FCE (%) Survival (%) C low 18.15 ± 0.91 0.67 ± 0.01 28.15 ± 3.18ab 3.18 ± 0.07ab 31.44 ± 0.69b 62.5 ± 3.54b 30% C high 16.30 ± 3.39 0.63 ± 0.09 19.25 ± 0.91b 3.34 ± 0.35b 30.09 ± 3.16b 85.0 ± 0.00a In both carbohydrate cases (relative low and high contents), growth parameters increased their performance from 20% up to 30% CP and then descended to 40% CP. Mean biomass gain data was fitted to a quadratic model to estimate the protein requirement according to the dose-response relationship. Optimum and maximum protein requirements were obtained by applying the following quadratic model: y = -1080x2 + 618.6x - 52.35 (determination coefficient R2 = 0.927). Calculations indicate the corresponding optimum protein content to be 28.6% CP at low carbohydrate content (Fig. 1), other parameters modelled followed the same pathway. Each curve models for corresponding parameters can be seen in Figure 1. DISCUSSION In the present study, 30% CP + C low, showed significantly better results in evaluating the growth parameters such as biomass gain, FCR and FCE. Individual weight gain and SGR showed similar values with no significant differences. Survival was higher than 82% for most combinations except for 20% CP+C low (62%). Dietary protein content have been studied for other crustacean species such as Macrobrachium rosenbergii, ranging from 150 to 400 g kg-1 (Balazs & Ross, 1976; New et al., 1980; D’Abramo & Reed, 1988; Mitra et C low 20.25 ± 0.63 0.83 ± 0.01 36.00 ± 1.83a 2.32 ± 0.14a 43.15 ± 2.63a 95.0 ± 0.00a C high 18.05 ± 0.77 0.72 ± 0.09 22.70 ± 1.98b 3.74 ± 0.06b 26.72 ± 0.43b 92.5 ± 3.53a 40% C low 13.90 ± 1.69 0.57 ± 0.04 22.25 ± 1.20b 3.73 ± 0.30b 26.86 ± 2.19b 82.5 ± 3.54a C high 16.90 ± 2.68 0.65 ± 0.07 19.3 ± 1.41b 3.98 ± 0.37b 25.2 ± 2.39b 85.0 ± 0.0a al., 2005; Teshima et al., 2006). High dietary protein content (500 g kg-1) reported maximum growth of M. rosenbergii post larvae (Heinen & Mansi, 1991). If the dietary protein content are too low (diet with 230 g kg-1 CP) the growth rate will be reduced (Balazs & Ross, 1976); Boonyaratpalin & New (1982) and Bartlett & Enkerlin (1983) (diet with 150 g kg-1 CP) and Zaki et al. (2002) (diet with 150-250 g kg-1 CP). This may be due to the utilization of protein by M. rosenbergii muscle tissue to maintain other vital functions (Goda, 2008). On the other side, growth depression was reported in prawn fed diets exceeding their protein requirement due to the excess dietary protein being metabolized by prawns as a source of energy and nitrogen excreted as ammonia (Burford et al., 2004). Hari & Kurup (2003) suggested that further increase over 300 g kg-1 CP in dietary protein does not have any added advantage in M. rosenbergii. Moreover, for 400500 g kg-1 CP resulted in growth depression as it can also be seen in the present work. These protein contents are within 30-35% CP requirements for juvenile M. rosenbergii (D’Abramo & New, 2000). Ackefors et al. (1992) suggested that commercial diets for juvenile Astacus astacus may contain approximately 30-35% protein, 20-25% carbohydrate and not more than 10% lipids for the best growth rate. Ghiasvand et al. (2012) expressed that Astacus leptodactylus can be fed a practical diet containing 30% protein content. Celada et al. (1989) 840 5 Effects of protein and carbohydrate on juveniles of Samastacus spinifrons Individual weight gain (mg) 25 1 y = -422.5x2 + 232.25x - 11.4 R² = 0.9383 20 SGR a a 0,8 b ab 15 b 0,6 b y = -145x2 + 90x + 4.1 R² = 0.197 10 y = -8.3333x2 + 5.1x - 0.0567 R² = 0.3838 0,4 0,2 5 Low carbohydrate High carbohydrate 0 10% 20% 30% 10% 40% 20% 10 FCR 4 b 20 y = -342.5x2 + 205.75x - 8.2 R² = 0.7762 5 -1080x2 + 618.5x - 52.35 R² = 0.9502 Low carbohydrate 0 10% 20% High carbohydrate 30% 40% a y = 113.67x2 - 65.433x + 11.72 R² = 0.9628 1 Low carbohydrate 10% 20% 10 y = -750x2 + 450x + 25 R² = 0.9 100 b a 80 b 20 40% Survival (%) 120 a 30 30% Diet protein level FCE 40 High carbohydrate 0 Diet protein level 50 b b 3 2 y= 40% y = -18.833x2 + 13.45x + 1.4033 R² = 0.3891 ab 25 15 5 a 30 30% Diet protein level Biomass gain (%) 35 High carbohydrate Low carbohydrate 0 Diet protein level 40 y = -20.667x2 + 11.9x - 0.88 R² = 0.9735 y = 93.667x2 - 80.667x + 42.483 R² = 0.7029 y = -1400x2 + 817.1x - 75.98 R² = 0.972 Low carbohydrate High carbohydrate b 60 c 40 20 y = -2250x2 + 1450x - 137.5 R² = 0.9847 Low carbohydrate High carbohydrate 10% 30% 0 0 10% 20% 30% 40% Diet protein level 0% 20% 40% 50% Diet protein level Figure 1. Protein content curves behavior of growth parameters and survival under low and high carbohydrate content in juveniles of Samastacus spinifrons. Same letters above points at low carbohydrate curve mean no significant differences. High carbohydrate curves did not present significant differences. reported that the best growth of juvenile Pacifastacus leniusculus was obtained with diets containing 27-33% protein from several fresh and artificially compounded diets and Gonzalez et al. (2012) expressed that a 40% of protein can be suitable in commercial dry diets for this species. For Cherax quadricarinatus, Webster et 6841 Latin American Journal of Aquatic Research al. (1994) indicated that a diet formulated with 33% protein appeared to be adequate for juvenile phase, whereas Zenteno-Savin et al. (2008) stated that 31% of protein is the content to satisfy nutritional requirements for optimal growth. Xu et al. (2013) reported that 2730% protein diet provided the same growth efficiency for Procambarus clarkia, P. leniusculus and P. clarkia. These last species seem to be closer to S. spinifrons in protein requirements than Cherax, which could be explained due temperature dependence as Cherax are more tropical than other colder species. Several statistical methods can be used to estimate nutrient requirements in dose-response experiments based on mathematical and biological assumptions and principles (Shearer, 2000). Estimates of requirements for maximum growth were obtained by fitting doseresponse data to a quadratic model. The results that S. spinifrons juveniles required between 28 and 29% dietary crude protein for optimum growth as a result to apply a model found (y = -1080x2 + 618.6x - 52.35). In this sense, Cortes et al. (2003) expressed protein requirement of 31%, calculated for C. quadricarinatus from using the same second order polynomial model than this present study (y = -0.0071x2 + 0.484x + 1.142). From a nutritional point of view, protein utilization indexes can be considered as good indicators of “protein sparing effect” (Goda, 2008). In the present study, the diet containing a protein content of 30% CP + C low, provided the highest growth indexes and dietary protein utilization efficiency compared with the higher dietary carbohydrate content. These results suggest that S. spinifrons could be using dietary carbohydrate as main energy source at lower contents to spare dietary protein for maximum growth. Similar results were obtained by D’Abramo & New (2000), and also by Goda (2008) for M. rosenbergii. Best FCR was presented at 30% CP + C low (2.32), less than those obtained by Jones et al. (1996) for C. destructor and Cortes et al. (2003) for C. quadricarinatus. Hari & Kurup (2003) reported their better FCR (2.84 and 2.89 for 300 and 350 g kg-1 CP diet, respectively) for M. rosenbergii juveniles, comparable with results obtained by Millikin et al. (1980), Ashmore et al. (1985) and Gomez et al. (1988). The decreased growth rate showed by juveniles over 40% CP can be attributed to the high rate of protein catabolism (Hari & Kurup, 2003). Growth depression was already reported in prawn fed diets exceeding their protein requirement as a result of toxicity (Zein-Eldin & Corliss, 1976). Regarding carbohydrate utilization, Bautista & Subosa (1997) mentioned that protein contents in diets improve growth when combined with carbohydrate contents. This means that carbohydrate is used as an economical energy source. In this study, two relative contents of carbohydrate were used: low content (16.3 to 23.5%) and high content (34.6 to 35.8%). Results showed that low relative content is enough to keep better growth parameters. In this sense, carbohydrate is used to build quitine (main component of exoskeleton) and also a component of fatty acids and sterols (Clifford & Brick, 1978; Kucharski & Da Silva, 1991; CruzSuarez, 1996). Diaz-Herrera et al. (1992) reported carbohydrates as main energy sources for metabolic requirements in post larvae and juveniles of M. rosenbergii; later supported by Luna et al. (2007). Rosas et al. (2000) stated the possibility to reduce protein contents in diets by carbohydrates included as starch ingredient. Survival for CP + Carbohydrate combinations showed values higher than 82%, except in 20% CP + C low (62.5%). They can be compared with others. Survival values during a period up to 94 days ranged between 65-85% for C. destructor (Jones et al., 1996). For C. quadricarinatus, Ponce et al. (1998) 60-95% of survival rate; Webster et al. (1994) 50-71%; Thompson et al. (2003a) 56-80%; Thompson et al. (2003b) 95100%; Jacinto et al. (2003) 65-89%; and Muzinic et al. (2004) 79-98%. 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Anais da 27 Reuniao Anual da Sociedade Brasileira de Zootecnia e 12 Reuniao da Asociacao Latino-Americana de Producto animal Campinas, Fundacao de Estudos Agrarios Luiz de Queiroz (FEALQ), Piracicaba, pp.737-778. Webster, C.D., L.S. Goodgame-Tiu, J.H. Tidwell & D.B. Rouse. 1994. Evaluation of practical feed formulations with different protein levels for juvenile red claw crayfish (Cherax quadricarinatus). Trans. Kentucky Acad. Sci., 55: 108-112. Xu, W., W. Liu, M. Shen, G. Li, Y. Wang & W. Zhang. 2013. Effect of different dietary protein and lipid levels on growth performance, body composition of juvenile red swamp crayfish (Procambarus clarkii). Aquacult. Int., 21(3): 687-697. Zaki, M.A., H.A. Mabrouk & A.A. Nour. 2002. Optimum dietary protein levels and stocking density for freshwater prawn Macrobrachium rosenbergii juveniles reared in concrete basins. Egyp. J. Anim. Produc., 7: 161-168. Effects of protein and carbohydrate on juveniles of Samastacus spinifrons Zein-Eldin, Z. & J. Corliss. 1976. The effect of protein levels and sources on growth of Penaeus aztecus. In: T.R.V. Pillay & J.A. Dill (eds.). Advances in Aquaculture. FAO Technical Conference on Aquaculture, Kyoto, Japan. Fishing News Books, Farnham, pp. 592-596. Received: 14 November 2014; Accepted: 10 July 2015 8449 Zenteno-Savin, T., E. Cortes-Jacinto, J. Vasquez-Medina & H. Villarreal-Colmenares. 2008. Oxidative damage in tissues of juvenile crayfish (Cherax quadricarinatus von Martens, 1808) fed with different levels of proteins and lipids. Hidrobiologica, 18(2): 147-154. Lat. Am. J. Aquat. Res., 43(5): 845-855, 2015 Diversidad de la macrofauna en fondos blandos de Cuba DOI: 10.3856/vol43-issue5-fulltext-5 845 Research Article Diversidad y distinción taxonómica de la macrofauna en fondos blandos de la plataforma norte y suroccidental cubana Gema Hidalgo1, Wilmer Toledo2 & Alejandro Granados-Barba3 Posgrado en Ecología y Pesquerías, Universidad Veracruzana, Independencia 30 Col. Centro, 94290, Boca del Rio, Veracruz, México 2 Instituto de Oceanología, 1ra. 18406 entre 184 y 186, Playa, La Habana, Cuba 3 Instituto de Ciencias Marinas y Pesquerías, Universidad Veracruzana, Hidalgo 617 Col. Río Jamapa, 94290, Boca del Río, Veracruz, México 1 Corresponding author: Gema Hidalgo ([email protected]) RESUMEN. Se evaluó la diversidad de la macrofauna en fondos blandos de la plataforma marina cubana norte y suroccidental. Se utilizaron índices de variación taxonómica que aportan una nueva dimensión en la interpretación de la diversidad de las comunidades, que son independientes del tipo de hábitat y del esfuerzo de muestreo, y tienen respuesta monotónica ante las perturbaciones del ambiente. La heterogeneidad de taxones fue significativamente mayor en los biotopos areno-fangoso con vegetación, arenoso con vegetación y arenoso con vegetación sobre fondo duro. La diversidad por biotopos reflejó un gradiente de menor a mayor tamaño de partícula y de ausencia a presencia de vegetación. La distinción taxonómica promedio (Δ +) esperada en estas zonas de la plataforma cubana es de 92,5, con límites de confianza de 95% entre 76,7 y 100. Las estaciones con distinción taxonómica promedio <92,5 y fuera del límite de confianza inferior, se pueden considerar con condiciones ambientales de deterioro o que favorecen la diversidad de algún grupo en particular. Los grupos dominantes en esta fracción del bentos son crustáceos y poliquetos, como ocurre en otras regiones tropicales y templadas. Estos resultados sirven de base para la evaluación y monitoreo ambiental del macrozoobentos como componente clave del funcionamiento de ecosistemas marinos en fondos blandos de Cuba. Palabras clave: macrozoobentos, diversidad, distinción taxonómica, fondos blandos, Cuba. Macrofaunal diversity and taxonomic distinctness in soft bottoms of the northern and southwestern Cuban shelf ABSTRACT. Diversity of macrofaunal groups in soft bottoms of the northern and southwestern Cuban shelf was assessed using taxonomic indices that depend on community structure, are independent of habitat type and sampling effort, and have a monotonic response to environmental disturbances. Taxa heterogeneity was significantly higher in sandy-muddy with vegetation, sandy with vegetation, and sandy with vegetation on hard bottom substrates. Biotopes diversity showed a gradient from smaller to greater particle size and from absence to presence of vegetation. Average taxonomic distinctness expected in these zones of the Cuban marine shelf is 92.5 with 95% confidence limits between 76.7 and 100. Sites with average taxonomic distinctness lower than 92.5 and outside the estimated confident limits can be considered environmentally deteriorated or favoring diversity of some particular groups. Dominant groups in this benthos fraction are crustaceans and polychaetes, which is consistent with studies in other tropical and temperate regions. These results constitute a baseline for environmental assessment and monitoring of macrofauna in Cuban soft bottoms, as a key component for marine ecosystems functioning. Keywords: macrofauna, diversity, taxonomic distinctness, soft bottoms, Cuba. INTRODUCCIÓN Los estudios sobre comunidades de la macrofauna bentónica a nivel mundial son numerosos y diversos; __________________ Corresponding editor: Diego Giberto entre éstos, se ha destacado su uso como bioindicadores de contaminación y perturbaciones ambientales (Covazzi-Harriague et al., 2007; Pires-Vanin et al., 2011), así como de la degradación de hábitats provoca- 846 Latin American Journal of Aquatic Research dos por actividades antrópicas como la minería (Savage et al., 2001), dragado (Chessa et al., 2007), eutrofización (Ferreira et al., 2011), actividades turísticas, portuarias, descargas residuales urbanas e industriales, y derrames de petróleo (Uhrin & Holmquist, 2003; Muniz et al., 2013; Pires-Vanin et al., 2013; Souza et al., 2013). En otro ámbito, se ha evaluado también la complejidad estructural del hábitat y su influencia sobre el macrozoobentos (Attril et al., 2000; Arocena, 2007), mientras que Biles et al. (2002), Norling et al. (2007), Lloret & Marín (2011) y Kristensen et al. (2014) analizaron la actividad bioperturbadora de estos organismos y su relación con la funcionalidad del ecosistema, estructura de comunidades y flujo de nutrientes en el sedimento. Otro aspecto común es destacar la importancia de la macrofauna asociada a especies de interés económico, e.g., con relación a fondos de pesca de camarón (Scelzo et al., 2002; Valdés et al., 2011), bancos ostrícolas (Susan-Tepetlan & Aldana-Aranda, 2007; Hernández-Ávila et al., 2013) y nidos de Malacanthus plumieri (Gutiérrez-Salcedo et al., 2007). En Cuba, la importancia ecológica y económica de las comunidades bentónicas ha sido reconocida desde la década de los 70’ en varios estudios (Armenteros et al., 2007; Arias-Schreiber et al., 2008; Ocaña et al., 2012). No obstante, no hay trabajos integradores sobre atributos de las comunidades de la macrofauna en fondos blandos de la plataforma marina cubana. Los estudios realizados son dispersos, y no tienen homogeneidad en cuanto a métodos de muestreo pues responden a diferentes objetivos. La diversidad bentónica es un indicador ampliamente utilizado, entre otros componentes del ecosistema, para evaluar la integridad ecológica en aguas marinas (Borja et al., 2009), y generalmente se hace a través del uso de índices que tienen diferentes consideraciones para su aplicación. Los índices de diversidad "tradicionales" tienen problemas con la dependencia del tamaño de muestra, y al momento de diferenciar las variaciones ambientales naturales de aquellas inducidas por acciones humanas (Mouillot et al., 2005). Al depender del esfuerzo de muestreo, estos índices subestiman la riqueza taxonómica real, por lo que se han propuesto herramientas tales como los índices de diversidad basados en la distancia taxonómica, definida por el número de nodos o longitud de la vía entre especies en el árbol o jerarquía taxonómica linneana (Warwick & Clarke 1995, 2001; Clarke & Warwick 1998, 2001a), como medida de su relación filogenética y presumiblemente funcional (Ricotta, 2005, Ricotta & Szeidl, 2006). Los índices de diversidad taxonómica se han estado valorando en diferentes ambientes (e.g., rocosos y dulceacuícolas) (Terlizzi et al., 2005; Heino et al., 2007), regiones y latitudes (e.g., polares, templadas y tropicales) (Conlan et al., 2004; Miranda et al., 2005; Nicholas & Trueman, 2005; Włodarska-Kowalczuk et al., 2005; Leonard et al., 2006), siendo una herramienta potencialmente útil para evaluar la diversidad en fondos blandos de distintas zonas de la plataforma insular cubana. El uso de los índices mencionados contribuye a la comprensión de la estructura y distribución de las comunidades para el monitoreo de los cambios en la calidad ecológica de los hábitats. En consecuencia, el propósito del presente estudio es comparar la abundancia de la macrofauna en diferentes biotopos sedimentarios de la plataforma marina cubana, y analizar su diversidad mediante el uso de diferentes índices ecológicos. MATERIALES Y MÉTODOS Diseño de la investigación Se analizó la diversidad taxonómica de la macrofauna en fondos blandos someros de la costa norte y suroccidental de Cuba (<20 m de profundidad). A partir de la literatura, bases de datos y mapas temáticos elaborados entre 1975 y 2009, se obtuvo datos de abundancia provenientes de 270 estaciones localizadas en diferentes zonas de la plataforma insular, y distribuidas como sigue: 22 en el archipiélago Los Colorados, Pinar del Río, zona noroccidental (Ibarzábal, 1982), 3 en Canasí, al Este de La Habana, zona noroccidental (Martínez-Daranas & Hidalgo, 2003), 74 en el Archipiélago Sabana Camagüey, zona norcentral (Jiménez & Ibarzábal, 1982; Sánchez-Noda et al., 2006), 19 en Moa, Holguín, zona nororiental (Hidalgo, 2004; Hidalgo & Busutil, 2008), 152 en el Golfo de Batabanó, zona suroccidental (Ibarzábal, 1990, 1993; Arias-Schreiber et al., 2008; Hidalgo & Areces, 2009). Los biotopos de las 270 estaciones se clasificaron, utilizando la información de mapas temáticos y/o descripciones de los tipos de fondo en la literatura consultada, de acuerdo al tamaño predominante de partículas de sedimento y a la presencia de vegetación acuática sumergida (algas y/o pastos marinos): F: fango (sedimentos finos, con predominio de limos y arcillas), FV: fango con vegetación, AF: areno-fangoso, AFV: areno-fangoso con vegetación, A: arena (donde el diámetro medio de partículas es >0.063 mm), AV: arenoso con vegetación, R: capa de sedimento sobre fondo rocoso, RV: capa de sedimento con vegetación sobre fondo rocoso. Diversidad de la macrofauna en fondos blandos de Cuba El equipo utilizado para la toma de muestras en los trabajos analizados varió, incluyendo dragas de gravedad, nucleadores y draga de succión operada mediante buceo autónomo. Este último, sugerido por Thomassin (1978), se utilizó en 81 de las 270 estaciones analizadas (Fig. 1), recogiendo el sedimento en un área efectiva de 0.1 m2 y 10 cm de profundidad, hacia un saco recolector de 0.5 mm de abertura de malla. Se usó una manga cónica adosada al tubo de succión y al cilindro que delimita el área de muestreo, según lo recomendado por Ibarzábal (1987), para retener organismos de la fauna que escapan con facilidad durante la colecta. En todos los casos las muestras se fijaron en solución de formaldehído al 4%, neutralizado con tetraborato de sodio, y se obtuvo la macrofauna retenida en el tamiz de 500 μm, para su cuantificación e identificación hasta la menor resolución taxonómica posible. Análisis de datos Se utilizaron índices de diversidad univariados, tanto clásicos como taxonómicos. Para hacer el análisis mediante los índices clásicos, se consideraron solo las abundancias directamente comparables de individuos provenientes de las 81 estaciones muestreadas con draga succionadora. Se determinó la diversidad (H') de Shannon & Weaver (1949) y la equidad (J') de Pielou (1966). Al utilizar diferentes fuentes de información sobre abundancia de la macrofauna bentónica en zonas del archipiélago cubano, obtenidas con distintos objetivos, el nivel taxonómico al que se realizó la identificación dentro de cada grupo no fue parejo, llegando algunos hasta especies, como poliquetos con 86 en el Golfo de Batabanó (Arias-Schreiber et al., 2008) y 98 en el Archipiélago Sabana Camagüey (Ibarzábal, 2007), mientras que otros aparecen solo hasta taxones superiores. Por tal motivo, para uniformar protocolos y homogeneizar los grados de precisión y exactitud del análisis, en el presente estudio se analizó el nivel taxonómico de clases de macrofauna, incluyendo 26 en total. Adicionalmente, para los crustáceos de la clase Malacostraca, dada su representatividad y variabilidad taxonómica, se consideró la clasificación hasta órdenes, incluyendo 11 órdenes, lo que hizo un total de 36 grupos analizados. Se compararon los índices de diversidad (H´) y equidad (J´) entre biotopos, mediante análisis de varianzas y pruebas de comparación de medias post-hoc (Zar, 1999). En el caso de los datos no paramétricos se utilizó el análisis de varianza de 847 Kruskal-Wallis. Ambas pruebas estadísticas se realizaron con un nivel de significación de 0,05 utilizando el programa Statistica 7.0 (StatSoft, Inc. 2004). Para el total de las 270 estaciones analizadas, cuyas muestras se tomaron con diferentes equipos, se obtuvo los siguientes índices: diversidad taxonómica (Δ), distinción taxonómica promedio (Δ+) y variación de la distinción taxonómica (Λ+), propuestos por Warwick & Clarke (1995). Para el procesamiento de los datos se utilizó el programa Primer 6.0.2 (Clarke & Gorley, 2006). Diversidad taxonómica: 𝛥 = [ 𝛴𝛴𝑖<𝑗 𝜔𝑖𝑗 𝑥𝑖 𝑥𝑗 ] 𝑁(𝑁 − 1) [ ] 2 ωij es la distancia taxonómica entre todos los pares de especies i,j; N = Σi xi el número total de individuos de la muestra, y se utilizaron además las siguientes expresiones: Distinción taxonómica promedio: 𝛥+ = [ 𝛴𝛴𝑖<𝑗 𝜔𝑖𝑗 ] 𝑆(𝑆 − 1) [ ] 2 Variación de la distinción taxonómica: 2 𝛬 + = [ 𝛴𝛴𝑖<𝑗 (𝜔𝑖𝑗 − 𝛥+ ) ] 𝑆(𝑆 − 1) [ ] 2 S = es el número de especies de la muestra Para analizar la variabilidad regional de estos índices, se elaboró una tabla comparativa de los valores de Δ, Δ+ y Λ+ de la macrofauna en las zonas estudiadas. Los índices de diversidad taxonómicos tienen la ventaja de tener respuesta monotónica y ser independientes del tipo de hábitat, del tamaño de muestra y de la presencia de especies raras. No obstante, se vuelven imprecisos cuando se dispone de escasas estaciones de muestreo (Clarke & Warwick, 2001b). Por ello, al haber solo tres estaciones próximas a Canasí, al noreste de La Habana, no se consideró en la tabla de índices por zona. RESULTADOS Abundancia e índices de diversidad La abundancia media (ind m-2) por biotopo varió entre 364,1 y 1470,9, siendo >1000 ind m-2 en el arenofangoso con vegetación y arenoso con vegetación, con predominio de poliquetos (Tabla 1). Este grupo constituyó el 31,8% de la densidad total, seguido por anfípodos (9,8%), nemátodos (9,2%), ostrácodos (8,7%), tanaidáceos (8,2%), misidáceos (4,5%), cumá- 848 Latin American Journal of Aquatic Research Figura 1. Mapa del área de estudio con las 81 estaciones muestreadas con draga succionadora (puntos rojos), ubicadas frente a Canasí (3), en el Archipiélago Sabana Camagüey (35) y Golfo de Batabanó (43). ceos (4,1%), bivalvos (4,0%), decápodos (2,8%), gastrópodos (2,7%), isópodos (2,5%) y otros grupos menores. El índice de diversidad (H') fue significativamente mayor en el biotopo de sedimento con vegetación sobre fondo rocoso (RV). Este se diferenció significativamente de los demás biotopos, excepto del arenofangoso con vegetación (AFV) y del arenoso con vegetación (AV) (Fig. 2). Los biotopos de fango (F) y sedimento con vegetación sobre fondo rocoso (RV) mostraron las mayores diferencias significativas. En cuanto a la equidad (J´), no hubo diferencias significativas entre biotopos (Fig. 3). La diversidad taxonómica (Δ) de los 14 filos identificados varió por zonas geográficas entre 58,4 y 75,9, y la distinción taxonómica promedio (Δ+), entre 84,5 y 92,4 (Tabla 2). La mayor variación de la distinción taxonómica (Λ+) se observó en el Golfo de Batabanó y el Archipiélago Sabana-Camagüey. La distinción taxonómica promedio (Δ+) esperada en estas zonas de la plataforma cubana fue de 92,5; con límites de confianza del 95% entre 76,7 y 100 (Fig. 4). Fuera del límite de confianza se encontraron 13 estaciones con diferentes biotopos y números de taxones. La zona de mayor precisión del estadístico se encontró entre 10 y 20 taxones. Diversidad de la macrofauna en fondos blandos de Cuba 849 Tabla 1. Abundancia media (ind m-2) y error estándar de los grupos más abundantes (>5%) y total por biotopos; entre paréntesis se indica el número de estaciones. F: fango, FV: fango con vegetación, AF: areno-fangoso, AFV: areno-fangoso con vegetación, A: arena, AV: arenoso con vegetación, R: capa de sedimento sobre fondo rocoso, RV: capa de sedimento con vegetación sobre fondo rocoso. Grupo Polychaeta Amphipoda Nematoda Ostracoda Tanaidacea Total F(16) AF(5) A(7) R(6) FV(13) 62,4±13,4 25,5±11,5 29,4±18,3 24,4±13,8 70,9±47,6 369,9±104,3 59,9±17,1 65±35,1 6,7±6,6 9,3±6,4 15,6±7,2 461,1±330,9 210,9±33,7 27,3±16,2 32,4±17,3 29,5±14,9 19,7±12,5 517,4±111 261,7±122,6 35±26,3 106,7±40,5 20,0±6,4 173,9±137,7 703±159 131.4±39 82.5±24,6 25,4±15,4 23.6±11,5 20.2±4,1 364,1±105,7 Figura 2. Valores del índice de diversidad de ShannonWeaver por biotopos (media ± error estándar). F: fango, AF: areno-fangoso, FV: fango con vegetación, R: capa de sedimento sobre fondo rocoso, A: arena, AFV: arenofangoso con vegetación, AV: arenoso con vegetación y RV: capa de sedimento con vegetación sobre fondo rocoso. F (7,73) = 2,3649; P = 0,031. Las letras a, b y c indican diferencias significativas con P < 0,05. DISCUSIÓN Se encontraron diferencias claras en las comunidades en cuanto a su composición y abundancia, según el tipo de biotopo, mediante los valores del índice de diversidad de Shannon-Weaver. La complejidad de hábitats, dada por el mayor tamaño de partículas de los sedimentos y la presencia de vegetación, influyó en la diversidad de grupos que se obtuvo en los biotopos RV, AV y AFV. Los factores y mecanismos que explican la relación entre la complejidad estructural de los hábitats y los patrones ecológicos de la macrofauna han sido analizados por varios autores (e.g., Hewitt et al., 2005; Hauser et al., 2006; Cortés et al., 2012), demostrando AFV(21) AV(10) 538,6±159,6 349±159,1 186,2±57,4 93,7±29,8 79,4±24,7 188±134 180,6±73,2 104±42,5 76,4±22 51,8±11,2 1470,9±383 1037,1±379,3 RV(3) 166,7±61,8 36,7±13,8 47,8±33,4 98,9±14,4 33,3±10,7 668,9±127,4 Figura 3. Valores del índice de equidad de Pielou por biotopos (media ± error estándar). R: capa de sedimento sobre fondo rocoso, A: arena, AFV: areno-fangoso con vegetación, F: fango, AF: areno-fangoso, FV: fangoso con vegetación, AV: arenoso con vegetación y RV: capa de sedimento con vegetación sobre fondo rocoso. H (7,81) = 5,0235; P = 0,6571. la importancia que tiene, tanto el incremento en superficie disponible para la fauna, como la configuración espacial y rugosidad del hábitat en sí, formando una variedad de microhábitats que favorecen la mayor riqueza de organismos. En el presente estudio esto parece haber influido positivamente en las abundancias de poliquetos y ostrácodos en particular. Los grupos dominantes en los biotopos (poliquetos, crustáceos), se encuentran comúnmente con mayor diversidad en esta fracción del bentos. Esto se ha evidenciado en diferentes regiones tropicales (Eklöf et al., 2005; Gutiérrez-Salcedo et al., 2007; Díaz-Díaz et al., 2013), subtropicales (Pires-Vanin et al., 2011, 2013) y templadas (Ríos et al., 2003; Moreira & Troncoso, 2007). En el biotopo de sedimento con vege- 850 Latin American Journal of Aquatic Research Tabla 2. Índices de diversidad taxonómicos en cinco zonas de la plataforma insular cubana. (Diversidad taxonómica Δ, distinción taxonómica promedio Δ+, variación de la distinción taxonómica Λ+). Zonas Archipiélago Sabana-Camagüey Moa Archipiélago Los Colorados Golfo de Batabanó Canasí Δ 58.4 63.8 65.1 70.1 75.9 Δ+ 90.1 89.5 92.4 84.5 92.1 Λ+ 332.3 284.3 278.7 376.9 286.7 tación sobre fondo rocoso (RV) se puede encontrar mayor diversidad, ya que generalmente en este tipo de fondo el macrofitobentos se encuentra en parches, lo que contribuye a la heterogeneidad de nichos y recursos, y crea un efecto de borde que proporciona mayor superficie de intercambio entre comunidades (Hewitt et al., 2002; Bouma et al., 2009). Estas condiciones deben favorecer la equidad entre grupos, que fue mayor en este biotopo, aun cuando no hubo diferencias significativas. Los fondos arenosos y areno-fangosos con vegetación (AV y AFV) también fueron propicios para el desarrollo de grupos como poliquetos y anfípodos. En estos biotopos, además de la complejidad estructural del hábitat, influye una mayor disponibilidad de alimento, a partir de la trama creada por las estructuras vegetales en deposición y la retención de partículas que contribuyen al detrito. Otros autores (Neira & Palma, 2007; Pires-Vanin et al., 2013; Jordana et al., 2015) también observaron que el porcentaje de arena y contenido de materia orgánica son los principales factores ambientales que determinan la composición de la macrofauna en fondos blandos. En los biotopos fangosos y desprovistos de vegetación, la menor complejidad estructural del hábitat, baja disponibilidad de oxígeno y poca estabilidad de los sedimentos, deben haber influido en su menor diversidad. La distinción taxonómica promedio (Δ+) de las comunidades analizadas en el Archipiélago SabanaCamagüey (ASC) y Moa fue muy similar, cercana a 90; sin embargo, en el ASC hubo mayor variación de la distinción taxonómica (Λ+), lo que indica que en Moa la mayoría de los grupos pertenecen a pocos taxones superiores. Esto evidencia las condiciones a que se encuentra expuesta esta zona marina, con la influencia de efluentes y residuos sólidos asociados a procesos minero-metalúrgicos que se desarrollan en la región, así como de aportes fluviales provenientes de actividades urbana y portuaria (Rodríguez & Acero, 2006; Cervantes et al., 2009, 2011). Entre los principales problemas ambientales generados por dichas actividades, se encuentra la resus- Figura 4. Distinción taxonómica promedio (Δ+) de la macrofauna en fondos blandos de las zonas estudiadas de la plataforma marina cubana, con límites de confianza del 95%. pensión de sedimentos, modificaciones del relieve submarino y alteraciones de la dinámica de los sedimentos, ingreso de contaminantes químicos tóxicos e incremento en la concentración de nutrientes (Rodríguez, 2006; Rodríguez & Acero, 2006). Todos estos fenómenos provocan diferentes grados de impacto e inciden en general sobre la estructura de las biocenosis. La menor variación de la distinción taxonómica donde el impacto de la contaminación es mayor, ha sido referida por Warwick et al. (2002) al comparar dos zonas costeras en el Reino Unido. Además, Tweedley et al. (2015) encontraron correlaciones significativas de la distinción taxonómica promedio (Δ+) y de la variación de la distinción taxonómica (Λ+) con concentraciones de siete metales pesados, por lo que consideran estos índices apropiados como indicadores de perturbaciones antropogénicas, y que permiten plantear condiciones regionales de referencia. En el Archipiélago Los Colorados, se encontró la estructura más diversa de las comunidades analizadas (Δ+ = 92,4), lo que podría indicar mejor calidad de hábitats, pues esta área ha tenido menor grado de perturbación humana. Es también notable que los menores valores de diversidad taxonómica (Δ = 58,4 y Δ = 63,8) se registraron en zonas con mayor carga contaminante por la influencia de actividades industriales y urbanas, en algunas bahías interiores del Archipiélago Sabana-Camagüey (Montalvo-Estévez et al., 2013) y Moa (Cervantes et al., 2011). En el Golfo de Batabanó, aunque se observó la menor distinción taxonómica promedio, la variación de la distinción taxonómica fue la mayor encontrada. Esto puede estar relacionado con diferencias en las estructuras tróficas en los biotopos, que influyen Diversidad de la macrofauna en fondos blandos de Cuba notablemente en este estadístico; la reducción en la diversidad trófica conlleva una reducción en la distinción taxonómica, aunque no necesariamente en la riqueza de especies (Warwick & Clarke, 1998). Según Mackie et al. (2005), en la Isla de Seychelles los valores de Δ+ fueron inferiores a los del mar de Irlanda (zona templada) y de una estación en Hong Kong (zona subtropical). Sin embargo, un análisis estructural detallado de las jerarquías taxonómicas mostró que Seychelles e Irlanda tuvieron igual número de entidades taxonómicas superiores, a niveles de familia a orden, pero en Seychelles hubo mayor número de especies dentro de algunas familias en particular, lo que resultó en una reducción relativa de Δ+, que representa la distancia taxonómica promedio ponderada entre cada par de especies de la muestra, y en un incremento relativo de su variación Λ+. Los valores de Δ entre 58,4 y 70,1 al excluir las estaciones de Canasí, fueron intermedios entre los encontrados por Warwick et al. (2002) en el Reino Unido (20-80), lo que pudiera deberse, además de las variaciones que se deducen a priori a partir de la diferencia latitudinal, al grado de resolución taxonómica y a las escalas espaciales analizadas, así como a diferencias en las condiciones de perturbación y degradación de los hábitats. Este índice es altamente dependiente de la distribución de abundancia de los taxones y, por tanto, sigue muy de cerca los cambios de H'. En ese sentido, es notable que en el presente estudio los valores de H' también fueron intermedios a los encontrados en el Reino Unido (0,5-2,5), tanto por Warwick et al. (2002), como por Chainho et al. (2010). Las estaciones analizadas en la plataforma cubana que se encontraron por debajo de los límites de confianza de la distinción taxonómica promedio (Δ+), y con alto número de taxones, tienen mayor número de grupos inferiores pertenecientes a una misma categoría superior, lo que indica un ambiente más favorable para el desarrollo y diversidad dentro de ese taxón, como es en este caso Crustacea. No extraña entonces que la tendencia general de H' y J´ no coincida con la de este índice (Δ+), pero sí más con la de los índices diversidad taxonómica (Δ) y variación de la distinción taxonómica Λ+, siendo mayores como promedio en el Golfo de Batabanó (H' = 2,40 y J´ = 0,69) que en el Archipiélago Sabana-Camagüey (H' = 2,27 y J´ = 0,63). El conocimiento actual sobre ecología de la macrofauna en hábitats tropicales es limitado comparado con el de zonas templadas y subtropicales (Helguera et al., 2011). En estos ambientes, dicha fracción del bentos alcanza una alta diversidad, incluso dentro de algunos taxones superiores como Polychaeta (Hernández-Alcántara et al., 2014). De ahí que el trabajo con niveles taxonómicos superiores a especie, o con grupos en particular, se ha considerado con fines prácticos en algunos estudios de evaluación de 851 impactos y biomonitoreo de la calidad ambiental, para optimizar el tiempo operacional y la relación costo/beneficio (Muniz & Pires-Vanin, 2005; Musco et al., 2009). En ocasiones se ha utilizado un enfoque de metanálisis a nivel de phylum, para comparar la severidad del estrés de las comunidades por perturbaciones antropogénicas en amplias regiones, pues las variaciones por causas naturales son menos evidentes a nivel de grandes grupos que de especies (Warwick & Clarke, 1993; Venturini et al., 2004; Somerfield et al., 2006). También se ha encontrado que el nivel taxonómico de familia es, en general, suficiente para evaluar los efectos de la contaminación en ambientes de sustratos blandos, sublitorales y estuarinos (Domínguez-Castanedo et al., 2007; Marrero et al., 2013). Al no contar con información homogénea de las abundancias hasta nivel de familias o especies de todos los grupos macrobentónicos en las zonas de estudio, el presente trabajo constituye un análisis general de la diversidad hasta grandes grupos, que aporta por primera vez un valor esperado de distinción taxonómica promedio (Δ+) de la macrofauna y sus límites de confianza en la plataforma cubana, como base o referencia para la prospección y monitoreo de estas comunidades, mediante el uso de estos índices de diversidad que no dependen del tipo de hábitat ni del tamaño de muestra, y para la descripción de los patrones detallados de especies en cada zona. CONCLUSIONES - Los biotopos con mayor diversidad de la macrofauna en fondos blandos de las zonas estudiadas de la plataforma cubana fueron areno-fangoso con vegetación (AFV), arenoso con vegetación (AV) y sedimento con vegetación sobre fondo rocoso (RV), reflejando un gradiente de menor a mayor tamaño de partícula y de ausencia a presencia de vegetación. - Las estaciones con distinción taxonómica promedio de la macrofauna menor que 92,5 y por fuera del límite de confianza inferior estimado, se pueden considerar con condiciones ambientales de deterioro, o que favorecen la diversidad de algún taxón en particular. - Los grupos dominantes de la macrofauna en fondos blandos de las zonas de estudio fueron poliquetos y crustáceos, lo que coincide con lo encontrado por otros autores en regiones tropicales y templadas. AGRADECIMIENTOS Agradecemos a Rosa del Valle y Macario Esquivel por su contribución en la búsqueda bibliográfica, al 852 Latin American Journal of Aquatic Research Consejo Científico del Departamento de Bentos del Instituto de Oceanología por las sugerencias en la elaboración del presente trabajo, a la Secretaría de Relaciones Exteriores del Gobierno de México y al Posgrado en Ecología y Pesquerías de la Universidad Veracruzana por su apoyo en la fase final del manuscrito, así como a los revisores anónimos y editores por sus comentarios y propuestas para mejorar el mismo. REFERENCIAS Arias-Schreiber, M., M. Wolff, M. Cano, B. MartínezDaranas, Z. Marcos, G. Hidalgo, S. Castellanos, R. del Valle, M. Abreu, J.C. Martínez, J. Díaz & A. Areces. 2008. Changes in benthic assemblages of the Gulf of Batabanó (Cuba) results from cruises undertaken during 1981-85 and 2003-04. Pan-Am. J. Aquat. Sci., 3(1): 49-60. Armenteros, M., J.P. Williams, G. Hidalgo & G. González-Sansón. 2007. 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Box 592, La Paz, 23096 Baja California Sur, México Corresponding author: Arturo Tripp-Quezada ([email protected]) RESUMEN. La distinción taxonómica es una medida de diversidad que presenta una serie de ventajas que dan connotación relevante a la ecología teórica y aplicada. La utilidad de este tipo de medida como otro método para evaluar la biodiversidad de los ecosistemas marinos bentónicos de fondos blandos del Golfo de Batabanó (Cuba) se comprobó mediante el uso de los índices de distinción taxonómica promedio (Delta+) y la variación en la distinción taxonómica (Lambda+) de las comunidades de moluscos. Para este propósito, se utilizaron los inventarios de especies de moluscos bentónicos de fondos blandos obtenidos en el periodo 1981-1985 y en los años 2004 y 2007. Ambos listados de especies fueron analizados y comparados a escala espacial y temporal. La composición taxonómica entre el periodo y años estudiados se conformó de 3 clases, 20 órdenes, 60 familias, 137 géneros y 182 especies, observándose, excepto en el nivel de clase, una disminución no significativa de esta composición en 2004 y 2007. A escala espacial se detectó una disminución significativa en la riqueza taxonómica en el 2004. No se detectaron diferencias significativas en Delta+ y Lambda+ a escala temporal, pero si a escala espacial, hecho que se puede atribuir al efecto combinado del incremento de las actividades antropogénicas en la región con los efectos inducidos por los huracanes. Estos resultados sugieren que el par de índices Delta+ y Lambda+ son buenos descriptores de la biodiversidad de las comunidades de moluscos bentónicos de fondos blandos del Golfo de Batabanó. Palabras clave: moluscos, distinción taxonómica, biodiversidad, fondos blandos, Golfo de Batabanó, Cuba. Taxonomic distinctness of soft-bottoms mollusks from Gulf of Batabanó, Cuba ABSTRACT. Taxonomic distinction is a measure of diversity that has a number of advantages that provides relevant connotation to theoretical and applied ecology. The usefulness of this type of measure as an alternative method for assessing the biodiversity of soft-bottom benthic marine ecosystems was tested using the indices of average taxonomic distinctness (Delta+) and variation in taxonomic distinctness (Lambda+) for mollusk communities of the Gulf of Batabanó (Cuba). For this purpose, inventories of soft bottom benthic mollusk species obtained in the period 1981-1985 and the years 2004/2007 were used. Both species lists were analyzed and compared at spatial and temporal scales. The taxonomic composition, between the period 1981-1985 and years 2004 and 2007, consisted of 3 classes, 20 orders, 60 families, 137 genera and 182 species observed. With the exception of the class level, a non-significant decrease of this composition in 2004 and 2007 was detected. At a spatial scale, a significant decrease in the taxonomic richness was observed in 2004. Significant differences were not detected in Delta+ and Lambda+ to time scale, but at spatial scale, results revealed significant differences that could be attributed to the combined effect of increased anthropogenic activities in the region with hurricane induced effects. These results suggest that the pair of indices, Delta+ and Lambda+, are good descriptors of the biodiversity of soft-bottom benthic mollusk communities in the Gulf of Batabanó. Keywords: mollusk, taxonomic distinctness, biodiversity, soft bottoms, Gulf of Batabanó, Cuba. INTRODUCCIÓN Para conocer los cambios o variaciones que tienen lugar en los ensamblajes de especies, sean estas ocasionadas _____________________ Corresponding editor: Ingo Wehrtmann por factores naturales y/o antropogénicos, la reconstrucción de datos históricos es un elemento esencial para lograr dicho objetivo (Falace, 2000). Los datos ambientales históricos pueden ser difíciles de interpretar 857 2 Latin American Journal of Aquatic Research cuando son analizados con medidas de riqueza y abundancia de especies. Lo expuesto anteriormente se debe a que esas medidas están afectadas por el tipo y complejidad del hábitat, métodos de muestreo, tamaño de muestra y esfuerzo de muestreo, así como por el conocimiento sistemático del grupo (o grupos) que esté bajo estudio o las discrepancias en la nomenclatura existente entre diferentes autores (Ceshia et al., 2007). Recientemente, algunos estudios ecológicos han propuesto el uso de las categorías taxonómicas superiores para evaluar los patrones espacio-temporales de la biodiversidad en las comunidades (Piazzi et al., 2002; Giangrande, 2003). En este contexto se han creados varios índices que incluyen en sus mediciones de diversidad, la afinidad taxonómica que existe entre las especies presentes en un sitio determinado. Dentro de estos, se tiene los índices de Distinción Taxonómica Promedio Delta+ (∆+, Clarke & Warwick, 1998) y la Variación de la Distinción Taxonómica Lambda+ (Λ+ Clarke & Warwick, 2001). Delta+ (∆+) es la distancia taxonómica promedio de las ramas del árbol taxonómico mediante el cual se conectan todos los pares de especies registradas en una muestra y puede interpretarse como la amplitud taxonómica promedio de la muestra. Lambda+ (Λ+) es la varianza de las distancias taxonómicas entre cada par de especies, que tiene la capacidad de distinguir diferencias entre la estructura taxonómica de las comunidades con algunos géneros que tengan alta riqueza de especies y otras con taxones superiores que tengan una o pocas especies. También se puede decir que este índice es un reflejo de cuan equitativo es el árbol taxonómico de una muestra (Clarke & Warwick, 1999). ∆+ y Λ+ están siendo ampliamente usadas para detectar los efectos causados por factores naturales y/o humanos en los ecosistemas (Brown et al., 2002; Ceshia et al., 2007; Hong & Zhinan, 2010; Tan et al., 2010; Xu et al., 2011, 2012). Esta utilidad se debe a que ambos índices no están influenciados por el número de especies, son poco afectados por el tipo y/o complejidad del hábitat y presentan un marco estadístico sobre el cual se puede obtener un valor estándar para realizar las comparaciones con los valores obtenidos a partir de las muestras de campo. Lo anterior evidencia que estos índices no precisan de sitios considerados como control (pocos perturbados) para probar la magnitud de sus cambios (Warwick & Clarke, 1995, 1998, 2001; Leonard et al., 2006). Además, sus cálculos se realizan a partir de simples listados o inventarios de especies, lo que les confiere un uso práctico en cuanto a costos y ahorro de tiempo y personal en la realización de estudios de monitoreo e impacto ambiental (Warwick & Light, 2002). La importancia y robustez de los índices de distinción taxonómica para evaluar la biodiversidad marina y el estado ecológico de los ecosistemas ha sido demostrada en diferentes grupos de organismos (Clarke & Warwick, 1998; Hall & Greenstreet, 1998; Price et al., 1999; Rogers et al., 1999; Warwick & Turk, 2002; Mouillot et al., 2005; Campbell & Novelo-Gutiérrez, 2007; Tan et al., 2010; Xu et al., 2011). También la sensibilidad de estos para detectar efectos negativos inducidos por las actividades humanas ha sido probada (Clarke & Warwick, 1998, 2001; Brown et al., 2002; Leonard et al., 2006; Somerfield et al., 2006; Hong et al., 2010; Xu et al., 2012) y cuestionada a través de diferentes escenarios de perturbaciones antropogénicas (Heino et al., 2005; Salas et al., 2006; Bevilacqua et al., 2011). Dentro de las comunidades zoobentónicas el Phylum Mollusca ha sido considerado como grupo focal para los estudios de biodiversidad en el ambiente marino, dado que es el segundo en cuanto a número de especies después de los artrópodos y presenta una gran variedad de taxones marinos bentónicos (Lalli & Parsons, 1997). Así mismo, los moluscos tienen un amplio espectro trófico que engloba prácticamente a todas las formas conocidas y presenta una elevada radiación evolutiva (Espinosa, 1992). Estas caracte-rísticas, hacen muy atractiva la sugerencia de utilizar a los moluscos para determinar los cambios o las variaciones en las comunidades ecológicas en una región determinada. En el Golfo de Batabanó (GB) los efectos de las perturbaciones naturales vinculadas al cambio climático (huracanes), combinados con diversas acciones antropogénicas (represamiento de los ríos, deforestación del manglar, construcción de diques, actividad industrial, entre otros), han permitido observar señales de deterioro ambiental en su medio físico y biológico. Dentro de los físicos, se han detectado cambios en la distribución textural de los sedimentos (Guerra et al., 2000) y en la evolución de la hidrodinámica sedimentaria (Acker et al., 2004). Como biológicos están la regresión y pérdida de áreas de pastos marinos en zonas en contacto con tierra firme en la costa norte del golfo (Cerdeira et al., 2008), cambios drásticos en la densidad, biomasa, riqueza de especies y estructura de las comunidades del bentos en varias zonas del litoral de su costa norte y al noreste de la Isla de La Juventud, asumiendo que estos cambios son debidos a las actividades humanas realizadas en la región desde hace 25 años (Arias-Schreiber et al., 2008). El objetivo del presente trabajo fue comprobar la aplicabilidad de los índices de distinción taxonómica en la malacofauna del GB, como herramienta para evaluar la biodiversidad en los ecosistemas bentónicos de fon- Distinción taxonómica de los moluscos del Golfo de Batabanó, Cuba dos blandos de esta región, analizando la estructura taxonómica de los ensamblajes de las especies de moluscos registradas en el periodo 1981-1985 y los años 2004 y 2007. MATERIALES Y MÉTODOS Área de estudio El GB es un cuerpo de agua semicerrado ubicado en la región suroccidental de Cuba (Fig. 1). Tiene una superficie aproximada de 21.305 km2, con una profundidad media de 6 m (Cerdeira et al., 2008). En su litoral norte (N) y oeste (O), Isla de La Juventud y en los centenares de cayos existentes en esta región se localizan franjas de bosques de mangles. En el litoral sur (S) está limitada por cayos, bajos y arrecifes coralinos costeros que en determinadas regiones emergen en forma de crestas arrecifales (GonzálezFerrer et al., 2004) y en otras están interrumpidas por algunos canales de entrada que en ocasiones presentan comuni-cación con el océano abierto (Fig. 1). En el litoral norte se localizan la mayoría de los asentamientos humanos donde se producen contaminantes residuales industriales, agropecuarios y domésticos que son vertidos a su interior. La circulación de la corriente marina es de este a oeste y describe una curva suave hacia el norte con baja velocidad (10,6 cm s -1) (Emilsson & Tápanes, 1971). Sus fondos van desde fangosos sin vegetación a los arenosos, arenosos fangosos y fango arenosos con o sin vegetación. En los fondos cubiertos por pastos marinos la especie que predominó fue la fanerógama marina Thalassia testudinum (Banks & König, 1805), la cual se presentó en diferentes densidades (Cerdeira et al., 2008). Procedencia de los datos y nomenclatura Se utilizó la información disponible de moluscos de fondos blandos obtenida en 41 sitios de muestreo distribuidos en el GB (Tabla 1, Fig.1). Los datos provienen de nueve prospecciones ecológicas realizadas en el periodo 1981-1985, en que se muestrearon 20 sitios (Tabla 1, Fig.1a) y en los años 2004 y 2007 en que se muestreó 21 sitios, de los cuales 13 fueron analizados en el 2004 (Tabla 1, Fig. 1b) y 8 en el 2007 (Tabla 1, Fig. 1c). Varios sitios de muestreo en 2004 y 2007 se ubicaron en los mismos sitios muestreados durante 1981-1985, mientras que otros se localizaron en áreas próximas a estos para establecer comparaciones. Siete sitios (21, 23, 24, 25, 30, 31, 33) de muestreo del 2004 se confinaron próximos al litoral de la costa norte del golfo, mientras que en 2007 todos se ubicaron alejados de esta zona (Figs. 1b, 1c). El periodo que se analizó en este estudio fue de 26 años. 8583 La información de 1981-1985 se obtuvo de Alcolado (1990) y se refiere solamente a la presencia de las especies de moluscos por sitio de muestreo. El elenco sistemático de las especies de moluscos del año 2004 fue obtenido de la base de datos del Instituto de Oceanología y el de 2007 mediante un crucero de investigación realizado por especialistas del Centro de Investigaciones Pesqueras de Cuba. En ambos elencos sistemáticos se tiene el listado del número de individuos por especie de molusco por cada sitio de muestreo, arte de muestreo, número de réplicas (Tabla 1) y una descripción detallada del hábitat béntico donde se localizaron. Para la colecta de las muestras de moluscos se utilizó una rastra epibentónica constituida por un copo interno con una malla de 4 mm de abertura y otro externo, protector, con una malla de 1 cm de abertura. En el periodo 1981-1985 y los años 2004 y 2007 las dimensiones de las mallas usadas para la colecta de los moluscos fueron similares. La diferencia de la rastra varió solamente en la amplitud de su zona de arrastre (Tabla 1). Los organismos colectados fueron pasados por un tamiz de 4 mm de abertura de malla para separarlos del sedimento y se seleccionaron solamente los vivos. Debido a la diferente naturaleza de los datos del periodo 1981-1985 con respecto a los de 2004 y 2007 y a las variaciones en el esfuerzo de muestreo (Tabla 1), los datos fueron estandarizados como presencia/ ausencia (p/a). Dicha estandarización permitió hacer uso de los índices Delta+ y Lambda+ ya que basan sus análisis en datos cualitativos (p/a) y son robustos a las diferencias de esfuerzo de muestreo (Warwick & Clarke, 1995, 1998, 2001). Un análisis de la eficiencia de muestreo en el periodo 1981-1985 y los años 2004 y 2007 se realizó mediante los estimadores de riqueza de especies no paramétricos Chao-2, Jacknife-1 y Jacknife-2, cuyos cálculos se realizaron con el programa PRIMER v6.1 (Clarke & Gorley, 2006). El resultado obtenido demostró que la eficiencia fue mayor (82%) en el periodo 1981-1985 que en los años 2004 y 2007 (50 y 68% respecti-vamente). Este resultado limita el uso de los índices clásicos de diversidad (Shannon-Wiener, Riqueza de Margalef, entre otros), así como los análisis de abundancias de las especies con fines comparativos, que es el objetivo propuesto en este estudio. Dada las limitaciones expuestas con anterioridad, se utilizó el índice de frecuencia de aparición de las especies (número de sitios de muestreo donde las especies aparecen contra el número total de sitios), para determinar cuáles presentaron mayor frecuencia de aparición o distribución espacial en el periodo y años analizados. Este índice se expresó como un porcentaje. 4859 Latin American Journal of Aquatic Research principal (Cuba) para la Zona II y mayor influencia marina en la Zona III (Figs. 1a-1c). Los nombres de las especies registradas en cada período fueron actualizados con la literatura taxonómica más reciente: Espinosa et al. (1995); Espinosa & Ortea (1998, 1999, 2001, 2003); Ortea & Espinosa (2001) y Mikkelsen & Bieler (2008). El ordenamiento taxonómico se basó fundamentalmente en Bouchet et al. (2005), Espinosa et al. (2005, 2007) y Espinosa & Ortea (2010). Análisis de datos Para estimar los índices de distinción taxonómica, una clasificación Linneana de cinco niveles (clase, orden, familia, género y especie), también llamada lista madre, se utilizó como proxy para representar las relaciones taxonómicas de los individuos de todas las especies registradas en el periodo 1981-1985 y años 2004 y 2007. Se estimaron los índices de Distinción Taxonómica Promedio (Delta+, ∆+) y Variación de la Distinción Taxonómica (Lambda+, Λ+) de las muestras a partir de las ecuaciones propuestas por Clarke & Warwick (1998, 2001). ∆+ = [∑∑ i<j w ij]/ [S(S-1)/2] Λ+ = [∑∑ i<j (wij -∆+) 2]/ [S(S-1)/2] Figura 1. Sitios de muestreos (números) de moluscos de fondos blandos del Golfo de Batabanó en el período 19811985 (a) y los años 2004 (b) y 2007 (c). Las líneas discontinuas señalan los límites imaginarios de las zonas (Zona I, Zona II y Zona III), en que se dividió la región estudiada. Para facilitar el análisis espacial la región se dividió en tres zonas de acuerdo al criterio de Arias-Schreiber et al. (2008). La Zona I, se enmarcó entre la Ensenada de La Broa y las aguas adyacentes del poblado Batabanó, Guanimar y el sector este del sur de la provincia de Pinar del Río, cerca de Punta Capitana, que se caracterizó por presentar la mayor concentración de focos contaminantes en la región (Perigó et al., 2005). La Zona II ubicada en la región oeste y Zona III ubicada en la región este, fueron propuestas considerando una mayor influencia de tierra firme de la isla dónde: wij es la distancia taxonómica (peso taxonómico) a través del árbol de clasificación Linneana de cualquier par de individuos, siendo el primero para la especie i y el segundo para la especie j y S el número total de especies en la muestra. El peso taxonómico (wij) es un valor que debe aumentar con la separación taxonómica entre las especies y para este trabajo los valores fueron dados de forma tal que hubiese un incremento constante de un nivel a otro, según lo propuesto por Clarke & Warwick (1999). Los valores de ∆+ y Λ+ fueron calculados usando la rutina Diverse del programa PRIMER 6.1 (Clarke & Gorley, 2006). Análisis espacio-temporal de los índices de distinción taxonómica A partir de la lista madre de especies de toda la región, con la subrutina Taxdtest del programa PRIMER 6 v.1 (Clarke & Gorley, 2006), se calcularon a través de la generación de submuestras (sublistas de números de especies) provenientes de 1000 iteraciones aleatorias sin remplazo los valores esperados de ∆+ y Λ+. Estos valores generan una distribución de probabilidad en forma de embudo con contornos de confianza al 95% cuando se grafican contra el número de especies. Este análisis se consideró para comparar los valores calculados de estos índices a partir de las muestras con los esperados o calculados a partir del proceso de iteración. Para el cálculo de los índices de distinción 8605 Distinción taxonómica de los moluscos del Golfo de Batabanó, Cuba Tabla 1. Tipo de arte, sitios y esfuerzo de muestreo y tipo de datos de las prospecciones ecológicas realizadas en el Golfo de Batabanó durante el periodo 1981-1985 y los años 2004 y 2007. A/m: amplitud o el ancho de la zona de arrastre (expresada en metros) de la rastra epibentónica. Número prospecciones ecológicas 7 Rastra epibentónica (1 m) Número/sitios muestreo 20 2004 1 Rastra epibentónica (0,70 m) 13 2007 1 Rastra epibentónica (0,70 m) 8 Periodo/Año 1981-1985 Arte/Muestreo taxonómica promedio y su variación se excluyeron los sitios 21 y 30, por presentar solo uno o dos individuos representando a una especie, lo que es insuficiente para realizar el cálculo de estos índices, ya que sus valores son atípicos (Clarke & Warwick, 1999). Esto condicionó al cálculo de los índices ∆+ y Λ+ solamente a 39 sitios. Para comprobar si la estructura taxonómica de la malacofauna de la región había tenido cambios a escala temporal en los 26 años, se calcularon los valores de los índices ∆+ y Λ+ para cada uno de los sitios muestreados en el periodo 1981-1985 y los años 2004 y 2007. Estos valores se contrastaron con la distribución probabilística en forma de embudo con límites de confianza del 95%. Análisis espacio-temporal de la estructura comunitaria de la malacofauna La riqueza taxonómica de la malacofauna de fondos blandos del GB se comparó entre el periodo 1981-1985 y los años 2004 y 2007 a escala espacial y temporal mediante el análisis del estadístico t. En aquellos casos que no se cumplió con la normalidad, se aplicó la prueba de Kruskal-Wallis (K-W). Además, se realizó el diagrama de caja y bigote (Box-Plot) para conocer cuales medianas diferían entre sí. Estos análisis estadísticos se realizaron con el programa Statgraphics Centurion XV (2007). La similitud de la estructura comunitaria entre 1981-1985 y los años 2004 y 2007 se comprobó mediante un análisis de clasificación, construyendo un dendrograma por el método de agrupamiento de pares con la media aritmética ponderada (UPGMA) (Clarke & Gorley, 2006). Las relaciones entre los sitios de muestreo (análisis espacial) se realizaron mediante la prueba de escalamiento multidimensional no métrico (nMDS). Para conocer el patrón de la estructura comunitaria de los moluscos de la región y para detectar la existencia de diferencias significativas entre los grupos formados se realizó la prueba ANOSIM (Clarke & Gorley, 2006). Las matrices de similaridad se obtuvieron mediante el uso del índice de Sorensen a Número réplicas Tipo/Datos Se desconoce Presencia/Ausencia 3 Número/Individuos 3 Número/Individuos partir de los datos de presencia/ausencia (p/a) de las especies. RESULTADOS Composición taxonómica Durante el periodo de estudio se registró un total de 182 especies de moluscos de fondos blandos en los 41 sitios de muestreo, distribuyéndose en 3 clases, 20 órdenes, 60 familias y 137 géneros (Anexo 1). Los bivalvos estuvieron representados por 89 especies, 10 órdenes, 23 familias y 71 géneros, los gasterópodos por 91 especies, 8 órdenes, 35 familias y 64 géneros, y los escafópodos por 2 especies, 2 órdenes, 2 familias y 2 géneros (Tabla 2). La composición taxonómica de las tres clases de moluscos (Bivalvia, Gastropoda y Scaphopoda), se caracterizó por una disminución del número de órdenes, familias, géneros y especies con respecto al periodo 1981-1985. Sin embargo dichas variaciones observadas no fueron significativas: bivalvos (t = 1,13; P = 0,36), gasterópodos (t = 2,67; P = 0,12) y escafópodos (t = 1,00; P = 0,40). La riqueza taxonómica disminuyó en 2004 y 2007 en todas las zonas estudiadas al compararla con la del período 1981-1985. Esta disminución fue estadísticamente significativa (K-W = 8,62; P = 0,03) para el 2004 debido a la baja riqueza encontrada en la Zona I (Fig. 2). Las tres clases de moluscos fueron halladas en el 95 y 35% de los sitios muestreados en el periodo 19811985 y 2007 respectivamente. Además, en el 2007 se registraron dos clases en el 65% de los sitios de muestreo. En el 2004 no se registraron las tres clases en ninguno de los sitios y se caracterizó por la presencia solamente de la clase Bivalvia en el 46,1% de los sitios. Desde el punto de vista temporal 32 especies de moluscos (17,5%) fueron comunes entre el periodo 1981-1985 y años 2004 y 2007 (Anexo 1). De las cuales 16 (50%) correspondieron a bivalvos, 15 (46,8%) a gasterópodos y 1 (3,1%) a escafópodos (Anexo 1). 861 6 Latin American Journal of Aquatic Research Tabla 2. Número de taxones en cada nivel de resolución taxonómica para cada clase de moluscos de fondos blandos del Golfo de Batabanó de los listados de especies analizados por cada año. Clases Bivalvia Gastropoda Niveles taxonómicos Orden Familia Género Especie Orden Familia Género Especie Scaphopoda Orden Familia Género Especie Año (s) 1981-1985 2004 10 8 21 14 59 28 72 32 7 6 35 16 65 20 89 20 2 2 2 2 1 1 1 1 1 1 1 1 2007 7 17 35 39 5 20 26 31 Total 10 23 71 89 8 35 64 91 2 2 2 2 Figura 2. Análisis espacial de la riqueza taxonómica de los moluscos de fondos blandos del Golfo de Batabanó registrada por zona (Zona I, Zona II y Zona III) para el período 1981-1985 y los años 2004 y 2007. Entre el 60% y 100% de los sitios muestreados se registraron 24 especies de moluscos en el periodo 19811985 y 9 en el 2007. Durante 1981-1985 esas especies estuvieron compuestas por 12 especies de bivalvos, 11 de gasterópodos y 1 de escafópodos y las del 2007 por 7 especies de bivalvos y 2 de gasterópodos. Ninguna especie fue registrada en el 60% de los sitios muestreados en el 2004 y solo 6 entre el 38 y 54% de los sitios y de ellas 5 fueron bivalvos y 1 de gasterópodos. Laevicardium serratum (100%), Cerithium eburneum (95%), Nassarius albus (95%), Columbella mercatoria (90%) y Antalis antillaris (90%) presentaron los mayores porcentajes de aparición durante 19811985. En el 2004 los bivalvos L. serratum, Tucetona pectinata y Chione cancellata presentaron los mayores porcentajes de aparición con el 54% de los sitios cada una, seguidas por Pitar fulminatus (46%), Ctena orbiculata y C. eburneum con el 38% cada una. En el 2007 los bivalvos Laevicardium serratum y C. cancellata se registraron en el 100% de los sitios de muestreo, seguidos por P. fulminatus y C. eburneum con el 87% cada una y T. pectinata con el 75%. Distinción taxonómica de los moluscos del Golfo de Batabanó, Cuba Variación temporal y espacial de la distinción taxonómica Los resultados expuestos en la Fig. 3 indican que ni en el periodo 1981-1985 ni en 2004 y 2007 se localizaron fuera de los contornos probabilísticos de la distribución esperada en ambos índices: Delta+ (∆+) y Lambda+ (Λ+). El valor esperado del índice de distinción taxonómica promedio ∆+ en los 26 años analizados fue de 87 y la variación en la distinción taxonómica Λ+ de 240. Los valores de ∆+ en 2004 y 2007 (86,21 y 86,90 respectivamente) fueron menores al de la media esperada y en 1981-1985 fue superior (87,28), no detectándose diferencias significativas (P > 0,05) en ambos casos. Para Λ+ los valores de los años 2004 (271,42) y 2007 (257,82) fueron superiores a la media esperada y menor (232,86) en 1981-1985, siendo no significativo (P > 0,05) (Figs. 3a-3b). Desde el punto de vista espacial la estructura taxonómica de los moluscos mostró diferencias significativas. Para ∆+ y Λ+ los sitios de muestreo del 19811985 se localizaron dentro de la distribución esperada con valores de ∆+ por encima o muy cerca de la media esperada (87) y con valores por debajo de la media esperada (240) para Λ+ (Figs. 3c-3d). Cuatro sitios (24, 25, 27 y 33) del año 2004 se localizaron fuera de la distribución esperada de ∆+, que presentaron valores menores (77,14; 81,44; 74, 29 y 58 respectivamente) y estadísticamente significativos (P ≤ 0,05) a la media esperada (87) y de estos el que presentó el menor valor fue el 33 (Fig. 3c). Para Λ+, cinco sitios de muestreo (24, 25, 27, 33 y 38) se localizaron fuera de la distribución esperada, de los cuales tres (24, 27 y 33) se ubicaron fuera del contorno probabilístico inferior y con valores bajos (48,98; 119,73 y 36 respectivamente) y significativos (P ≤ 0,05) respecto a la media esperada (240). Los sitios 25 de 2004 y 38 de 2007 se localizaron fuera y por encima del contorno probabilístico superior con valores altos (397,93 y 42,72 respectivamente) y significativos (P ≤ 0,05) respecto a la media esperada (Fig. 3d). Patrón espacio-temporal de la estructura comunitaria de los moluscos Los análisis de ordenación por escalamiento multidimensional no métrico (nMDS) y el de clasificación mostraron la formación de dos grupos bien definidos (Figs. 4a-4b). El análisis de clasificación identificó un grupo conformado por 2004 y 2007 y otro por 19811985 (Fig. 4a). El nMDS también identificó la formación de dos grupos pero en este caso de sitios de muestreo, los que están en correspondencia con el periodo y años analizados (Fig. 4b). El resultado del 862 7 ANOSIM mostró diferencias estadísticamente significativas entre los ensamblajes de moluscos del periodo 1981-1985 y los años 2004 y 2007 (R = 0,30; P = 0,01). DISCUSIÓN La no existencia de cambios significativos en la estructura taxonómica de los moluscos del periodo 1981-1985 y años 2004 y 2007 indicó que ambas estructuras se caracterizaron por la presencia de un buen número de categorías taxonómicas (elevada amplitud taxonómica), donde hubo una distribución equitativa de especies. Además, las especies que conformaron esta estructura taxonómica estaban taxonómicamente poco emparentadas entre sí. Situación similar se presentó en la composición taxonómica de las tres clases de moluscos registradas en el periodo 1981-1985 y años 2004 y 2007 (Tabla 2). El valor similar de ∆+ (87,28) en 1981-1985 y muy próximo (86,90) el del año 2007 respecto a la media esperada (87) (Fig. 3a), indicó que las estructuras taxonómicas de los ensamblajes de moluscos fueron las más estables durante los 26 años analizados. Dicha estabilidad pudo ser reflejo de un ambiente con muy bajo nivel de perturbación que permitió la coexistencia de un mayor número de especies en los diferentes hábitats bénticos de fondos blandos del GB. No obstante el valor ligeramente superior de ∆+ en el periodo 1981-1985 respecto a la media esperada, se debería a características ambientales muy particulares respecto a las de 2004 y 2007. La amplia distribución espacial (60-100% de los sitios de muestreo) de 32 especies de moluscos entre el periodo 1981-1985 y el 2007 demuestra la existencia de la estabilidad ambiental que existió en ese año al compararla con el año 2004. Sin embargo, el hecho que en el 95% de los sitios de muestreo se registraran las tres clases de moluscos y que la cantidad de especies de bivalvos (12) y gasterópodos (11) hayan sido similares en el periodo 1981-1985 indica que las condiciones ambientales en ese periodo fueron las más estables en los 26 años analizados. Las condiciones físicas, meteorológicas y bióticas de la región en el período 1981-1985 fueron muy diferentes a las de 2004 y 2007 y han quedado reflejadas en varios estudios, donde se ha demostrado la existencia de cambios sustanciales con el paso del tiempo. Puga et al. (2010) hallaron un aumento en la frecuencia e intensidad de los ciclones tropicales en Cuba a partir de 2001, muchos de los cuales afectaron al GB. Cambios de la hidrodinámica y depositación se- 863 8 Latin American Journal of Aquatic Research Figura 3. Embudo de confianza (media: línea discontinua e intervalos de confianza al 95%: línea continua) del índice de distinción taxonómica promedio (Delta+) y la variación de la distinción taxonómica (Lambda+) simulado de la lista madre de especies de moluscos del Golfo de Batabanó. Los puntos son los valores observados en el periodo 1981-1985 y años 2004 y 2007 (a y b: análisis temporal) y de los 39 sitios de muestreos (c y d: análisis espacial) analizados en el mismo periodo y años. Figura 4. a) Análisis de clasificación y b) ordenamiento multidimensional no métrico de la estructura comunitaria de los moluscos de fondos blandos del Golfo de Batabanó. Los sitios del 1-20 pertenecen al período 1981-1985 y del 21-41 a los años 2004 y 2007. Distinción taxonómica de los moluscos del Golfo de Batabanó, Cuba dimentaria (Giermo & Volkov, 1988; Acker et al., 2004; Guerra et al., 2000; Alonso-Hernández et al., 2011), así como de la calidad de las aguas y sedimentos (Perigó et al., 2005; Loza et al., 2007) y cambios en las comunidades bentónicas (Arias-Schreiber et al., 2008; Cerdeira et al., 2008; Lopeztegui & Capetillo, 2008), han sido señaladas en varias localidades del golfo, las que conjuntamente con la disminución en las capturas de especies de interés comercial (Claro et al., 1990; Baisre et al., 2003; Puga et al., 2010), dan indicios de cambios a escalas locales y mesoescala en esta región. La estructura taxonómica de los sitios de muestreo 24, 25, 27 y 33 del año 2004 se caracterizó por una reducción en el número de categorías taxonómicas (poca amplitud taxonómica) y una distribución desigual de las especies en esas categorías. Lo anterior indica que las especies que conformaron dicha estructura estuvieron taxonómicamente más emparentadas entre sí, demostrando la existencia de cierta inestabilidad ambiental. La menor distribución espacial (frecuencia de aparición de las especies <60% de los sitios de muestreo) de las especies de moluscos en el GB hallada en el año 2004 sería resultado de los efectos ocasionados por la combinación de factores naturales (huracanes) y humanos. El registro de una clase de moluscos en tres sitios de muestreo (21, 24 y 30), así como el hallazgo de dos clases en cuatro sitios (23, 25, 31, 33) que fueron ubicados en el litoral N del GB (Fig. 1b) dan evidencias que en esta región del golfo, los efectos inducidos por las actividades humanas (Montalvo et al., 2000; Perigó et al., 2005; MartínezDaranas et al., 2009) fueron una de las causas que afectaron la estructura taxonómica de los moluscos. Sin embargo, las diferencias en cantidad y tipo de moluscos registrados entre esos sitios, conllevan a pensar en que no todo el litoral N del GB presentó el mismo nivel de afectación generado por las actividades humanas. Esto requiere un estudio ecológico más detallado, que considere agentes contaminantes en agua y sedimentos, distancia a la costa de los sitios de muestreo y el análisis de varios grupos bentónicos para dilucidar la situación ambiental en esta región del golfo. Los valores bajos y significativos de ∆+ de los sitios de muestreo 24, 25, 27 y 33 del 2004, así como los bajos porcentajes de distribución espacial de las especies también pueden ser explicados por los efectos ocasionados por el impacto del huracán Charley (Categoría 3, escala Saffir-Simpson) en agosto de ese mismo año y a los inducidos indirectamente por los fuertes oleajes e intensas lluvias del huracán Iván (Categoría 5, escala Saffir-Simpson) durante su paso por los mares adyacentes al sur del golfo, un mes después (septiembre) del paso del Charley. Sin 864 9 embargo, los valores bajos y significativos de Λ+ observados en los sitios 24, 27 y 33 y alto y significativo para el sitio 25 proporcionan evidencias que el efecto de estos eventos no fue de igual magnitud en cada uno de ellos. En este contexto varias investigaciones han demostrado que los huracanes pueden inducir disminuciones, pérdidas o incrementos en la abundancia y diversidad de los organismos bentónicos de fondos blandos como fue la pérdida de algunas especies en Bahía Chesapeake, después del paso de la Tormenta Tropical Agnes en 1972 (Boesch et al., 1976) y en la comunidad bentónica de La Cuenca Cape Fear, después del Huracán Fran (Mallin et al., 1999). También la disminución no significativa en la infauna intermareal en Hawaii después del Huracán Iniki en 1992 (Dreyer et al., 2005), así como el incremento significativo de la diversidad de especies de invertebrados de fondos blandos, pero no significativo en el número total de individuos al Este de Virginia, después del Huracán Isabel (Hughes et al., 2009). Los huracanes son eventos catastróficos que alteran severamente los ecosistemas, induciendo un amplio rango de respuesta a la biota intermareal y submareal (Hughes et al., 2009). Esas respuestas estarán condicionadas según la intensidad y frecuencia de esos eventos, las características ecológicas de la zona impactada y determinados efectos negativos ocasionados por factores antropogénicos. Los más bajos y significativos valores de ∆+ y Λ+ hallados en los sitios 24 y 33 pudieron ser consecuencia de la combinación de los efectos ocasionados por los huracanes con las condiciones de deterioro que presentó la zona donde se ubicaron estos sitios debido a la pérdida de áreas de pastos marinos (Cerdeira et al., 2008). Esta situación es más drástica para el sitio 33 donde sus fondos están desprovistos de vegetación, además de presentar cierto nivel de afectación por contaminación orgánica (Perigó et al., 2005). Los efectos negativos observados en estos sitios (24 y 33) fueron similares a los obtenidos por Arias-Schreiber et al. (2008) e Hidalgo & Areces (2009), quienes detectaron diferencias significativas en la estructura de las comunidades bentónicas y valores bajos y significativos de biomasas y densidades del macrozoobentos en estos mismos sitios, al compararlos con los resultados obtenidos en 1981 por Alcolado (1990) e Ibarzábal (1990). También son similares a los obtenidos por Tan et al. (2010) y Xu et al. (2011) quienes demostraron que el par de índices ∆+ y Λ+ presentaron valores bajos y significativos en gradientes de estrés ambiental ocasionados por el impacto de diferentes actividades humanas. La reducción en el número de categorías taxonómicas observada en el sitio 27 se debería a la combi- 865 10 Latin American Journal of Aquatic Research nación de los efectos de los huracanes con las características intrínsecas del hábitat donde se localizó este sitio. Sus fondos se caracterizaron por ser fangosos con poca vegetación lo que habría generado determinadas condiciones ambientales que al combinarse con el efecto de los huracanes, afectaron la estructura taxonómica de las comunidades de moluscos. Ibarzábal (1982), Jiménez & Ibarzábal (1982) e Hidalgo & Areces (2009) registraron mayores diversidades de grupos taxonómicos en sustratos arenosos y arenofangoso con vegetación que en sedimentos fangosos, lo que refuerza la idea que el sustrato fangoso con vegetación puede estar imponiendo determinadas restricciones ambientales de manera natural que afectan la diversidad. La estructura taxonómica que caracterizó al sitio 25, aunque fue similar a la del sitio 27, reflejó la presencia de condiciones ambientales adversas. Señales de deterioro ambiental (pérdidas de áreas y/o disminución de cobertura de pastos marinos y presencia de altas densidades de especies oportunistas de poliquetos (Arias-Schreiber et al., 2008; Cerdeira et al., 2008) observadas en el área donde se localizó este sitio, hecho que puede justificar la afectación en la estructura taxonómica de estos organismos. La estructura taxonómica del sitio 38 muestreado en el 2007, indicó la presencia de una distribución desigual de las especies en las categorías taxonómicas. La escasa equidad registrada en bivalvos originó el alto valor y significativo de Λ+ (Fig. 3d). Dicha desigualdad se debió a la desproporción en el número de familias (3) y géneros (8) en el Orden Veneroida de la clase Bivalvia y a la elevada presencia de Tucetona pectinata (Orden Arcida). Respecto a los gasterópodos se observó una distribución equitativa de familias (1 ó 2 por orden) y géneros (1 por familia) en su estructura taxonómica. La baja heterogeneidad espacial que presentó este sitio ubicado en un fondo areno-fangoso sin o con muy poca vegetación, pudo causar la estructura taxonómica observada. Alcolado (1990), encontró en el periodo 1981-1985 que en el sector este del GB (zona donde se ubicó el sitio 38), se localizaron las mayores biomasas y densidades de bivalvos, evidencia que afirma que las condiciones ambientales en esta zona del golfo favorecen más a los organismos de esta clase de moluscos. Warwick & Clarke, (1995,1998) plantearon que los índices ∆+ y Λ+ no solamente pueden ser afectados por impactos antropogénicos o por contaminación ambiental, sino que también por las características edáficas del medio coincidiendo con los resultados observados en el sitio 38. Un resultado similar fue obtenido por Heino et al. (2005), Salas et al. (2006), Ceschia et al. (2007) y Bevilacqua et al. (2011) quienes al analizar la estructura taxonómica de los ensamblajes de diferentes organismos bentónicos en hábitats de sustratos blandos y duros en ríos y lagos de Finlandia y en varias regiones de la plataforma marina de Portugal, España e Italia, concluyeron que los índices ∆+ y Λ+ fueron afectados fuertemente por las características intrínsecas del hábitat, más que por la influencia antrópica. Análisis de la estructura comunitaria Desde el punto de vista espacial, los análisis de clasificación y multidimensional no métrico mostraron que las estructuras comunitarias de los moluscos en los años 2004 y 2007 fueron diferentes estadísticamente a las del periodo 1981-1985. Dicha diferencia se debería a: (1) la elevada similitud espacial (60-100% de los sitios de muestreo) en la composición de especies en el periodo 1981-1985 a diferencia de la baja similitud encontrada en 2004 y 2007; y (2) la similar equidad de especies de bivalvos y gasterópodos registrada en 19811985, respecto a la baja similaridad en la equidad en 2004 y 2007, en los cuales se observó la dominancia de bivalvos. El cambio de estructura comunitaria de los moluscos se explicaría por la inestabilidad ambiental registrada en 2004 y 2007. Esa inestabilidad ambiental fue mayor en el 2004 por haber sido la zona impactada directa o indirectamente por dos huracanes y por ubicarse sitios próximos al litoral de la costa N del GB, región afectada por la actividad antrópica (Perigó et al., 2005; Loza et al., 2007; Arias-Schreiber et al., 2008; Cerdeira et al., 2008; Lopeztegui & Capetillo, 2008). Un análisis detallado acerca de la elevada dispersión observada en los sitios de muestreo del 2004 (Fig. 4b), dio como resultado que varios de esos sitios se ubicaron fuera de los contornos de probabilidad de ∆+ (24, 25, 27 y 33) o presentaron valores bajos (24, 27 y 33) ó altos (25 y 38) de Λ+. Esto muestra que los resultados obtenidos por este par de índices, reflejan con cierta fidelidad, las características de los patrones de la estructura taxonómica de estos moluscos. Respecto a los cambios espaciales en la estructura taxonómica de los moluscos del GB puede resumirse que las mayores afectaciones se observaron en el litoral N de las tres zonas en que se dividió el golfo para su estudio. Sin embargo, en ciertas áreas (sitio: 27 de 2004 y 38 de 2007) no ubicadas en el litoral N, mostraron ciertos niveles de afectación en la estructura taxonómica de las comunidades de moluscos. Los resultados obtenidos permiten concluir que el par de índices ∆+ y Λ+ son buenos descriptores de la biodiversidad de la malacofauna de moluscos de fondos blandos del GB, así como para detectar los cambios ocurridos a escala temporal y espacial. La utilidad de Distinción taxonómica de los moluscos del Golfo de Batabanó, Cuba estos índices para revelar los efectos ocasionados por perturbaciones humanas y/o naturales también quedó demostrada, aunque para este caso en particular, se deberán desarrollar investigaciones futuras para confirmar estos resultados, contando con variables abióticas relacionadas con el impacto antrópico en la región, así como la existencia de información biótica y abiótica antes y después del paso de los huracanes. AGRADECIMIENTOS Se agradece el apoyo recibido por el proyecto SIP-IPN 20141032, así como al Instituto Politécnico Nacional de México a través de los programas, EDI, COFFA y BEIFI. 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Res., 18: 1213-1221. 869 14 Latin American Journal of Aquatic Research Anexo 1. Listado de especies ordenado en cinco niveles taxonómicos jerárquicos (clase, orden, familia, género y especies). Presencia (x) y especies comunes de moluscos (*) en el periodo 1981-1985 y años 2004 y 2007. Taxa Clase Bivalvia Arcida Arcoidea Glycymerididae Noetiidae Carditoida Crassatellidae Mytilliida Isognomonidae Mytilidae Pteriida Pinnidae Pteriidae Limida Limidae Ostreida Ostreidae Pectinoida Anomiidae Pectinidae Lucinoida Lucinidae 1981-1985 Acar domingensis (Lamarck, 1819) Anadara notabilis (Röding, 1798)* Arca imbricata (Bruguière, 1789)* Arca zebra (Swainson, 1833) Barbatia cancellaria (Lamarck, 1819) Fugleria tenera (C.B. Adams, 1845) Axinactis decusata (Linnaeus, 1758) Glycymeris undata (Linnaeus, 1778) Tucetona pectinata (Gmelin, 1791)* Arcopsis adamsi (Dall, 1886) x x x x Crassinella lunulata (Conrad, 1834) x Isognomon alatus (Gmelin, 1791) Isognomon radiatus (Anton, 1839) Brachidontes modiolus (Linnaeus, 1767) Hormomya exustus (Linnaeus, 1758) Lithophaga corrugata (Philippi, 1846) Lithophaga teres (Philippi, 1846) Modiolus americanos (Leach, 1815) Modiolus squamosus (Baeuperthuy, 1967) Musculus lateralis (Say, 1822) x x x x x x x Atrina seminuda (Lamarck, 1819) Pinna carnea (Lightfoot, 1786) Pinctada imbricata (Röding, 1798)* Pteria colymbus (Röding, 1798) x x x x Ctenoides mitis (Lamarck, 1807) Ctenoides scaber (Born, 1778) Lima caribaea (d´Orbigny, 1853) Limaria pellucida (C.B. Adams, 1846) x x x Dendostrea frons (Linnaeus, 1758) x Anomia simplex (d’Orbigny, 1853) Antillipecten antillarum (Récluz, 1853)* Argopecten gibbus (Linnaeus, 1758)* Caribachlamys ornata (Lamarck, 1819) Caribachlamys pellucens (Linnaeus, 1758) Caribachlamys sentis (Reeve, 1853) Euvola laurentii (Gmelin, 1791) Euvola raveneli (Dall, 1898) Euvola ziczac (Linnaeus, 1758) Lindapecten muscosus (Wood, 1828) Anodontia alba (Link, 1807) Callucina keenae (Chavan, 1971) Clathrolucina costata (d'Orbigny, 1846) Codakia orbicularis (Linnaeus, 1758)* Ctena orbiculata (Montagu, 1808)* Divalinga quadrisulcata (d’Orbigny, 1853)* Lucina pensylvanica (Linnaeus, 1758)* Lucinisca muricata (Spengler, 1778) Parvilucina pectinella (C.B. Adams, 1852) x x x x x Año(s) 2004 2007 x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x 870 15 Distinción taxonómica de los moluscos del Golfo de Batabanó, Cuba Continuación Taxa Clase Bivalvia Veneroida Cardiidae Chamidae Mactridae Semelidae Solecurtidae Tellinidae Ungulinidae Veneridae Myoida Corbulidae Clase Gastropoda Patellogastropoda Eoacmaeidae Vetigastropoda Calliostomatidae Fissurellidae Phasianellidae Trochidae 1981-1985 Americardia guppyi (Thiele, 1910) Americardia media (Linnaeus, 1758)* Dallocardia muricata (Linnaeus, 1758) Laevicardium serratum (Linnaeus, 1758)* Lucinidae sp. Papyridea soleniformis (Bruguière, 1789) Trigonocardia antillarum (d’Orbigny, 1853) Chama congregata (Conrad, 1833) Chama sarda Reeve, 1847 Mactrotoma fragilis (Gmelin, 1791) Semele bellastriata (Conrad, 1837) Semele proficua (Pulteney, 1799) Tagelus divisus (Spengler, 1794)* Acorylus gouldi (Hanley, 1837) Angulus mera (Say, 1834)* Eurytellina nitens C.B. Adams, 1845 Macoma tenta Say, 1834 Merisca aequistriata (Say, 1824) Merisca martinicensis (d'Orbigny, 1853) Psammotreta intastriata (Say, 1826) Scissula candeana (d’Orbigny, 1853)* Scissula sandix (Boss, 1968) Scissula similis Sowerby, 1806 Tellina radiata Linnaeus, 1758 Tellinella listeri (Röding, 1798) Diplodonta notata (Dall y Simpson, 1901) Diplodonta nucleiformis (Wagner, 1840) Diplodonta punctata (Say, 1822) Phlyctiderma semiaspera (Philippi, 1836) Anomalocardia cuneimeris (Conrad, 1840) Chione cancellata (Linnaeus, 1767)* Chionopsis intapurpurea (Conrad, 1840) Dosinia concentrica (Born, 1778) Globivenus rigida (Dillwyn, 1817) Gouldia cerina (C.B. Adams, 1845) Periglypta listeri (J.E.Gray, 1838) Pitar fulminatus (Menke, 1828) Pitar stimpsoni (Dall, 1889) Transennella conradina (Dall, 1884) Caryocorbula swiftiana (C.B. Adams, 1852) x x x Año(s) 2004 x x x x x x x x x x x x x x x 2007 x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x 1981-1985 Eoacmaea pustulata (Helbling, 1779) x Calliostoma jujubinum (Gmelin, 1791) Calliostoma pulchrum (C.B. Adams, 1850)* Diodora cayenensis (Lamarck, 1822 Diodora listeri (d’Orbigny, 1842) Emarginula phrixodes Dall, 1927 Eulithidium adamsi (Philippi, 1853) Eulithidium affine (C.B. Adams, 1850) Eulithidium bellum (M. Smith, 1937) Eulithidium thalassicola (Robertson, 1858) Cittarium pica (Linnaeus, 1758) Pseudostomatella coccinea (A. Adams, 1850) Pseudostomatella erythrocoma (Dall, 1889) Tegula excavata (Lamarck, 1822) x x x x x x x x x x x x x x x 2004 2007 x x x x x x 871 16 Latin American Journal of Aquatic Research Continuación Taxa Clase Bivalvia Turbinidae Cycloneritimorpha Neritidae Caenogastropoda Cerithiidae Cerithiopsidae Epitoniidae Eulimidae Modulidae Littorinimorpha Caecidae Calyptraeidae Cassidae Naticidae Ranellidae Rissoidae Strombidae Trividae Xenophoridae Neogastropoda Columbellidae Conidae Cystiscidae Fasciolariidae Marginellidae Tegula fasciata (Born, 1778)* Tegula lividomaculata (C.B. Adams, 1845) Lithopoma phoebium (Röding, 1798)* Turbo castanea (Gmelin, 1791)* 1981-1985 x x x x Smaragdia viridis (Linné, 1758) Año(s) 2004 x x x 2007 x x x x Cerithium eburneum (Bruguière, 1792)* Cerithium litteratum (Born, 1778) Cerithium lutosum (Menke, 1828) Cerithium muscarum (Say, 1832) Retilaskeya bicolor (C.B. Adams, 1845) Seila adamsi (H.C. Lea, 1845) Cycloscala echinaticosta (d’Orbigny, 1842) Epitonium lamellosum (Lamarck, 1822) Eulima bifasciata d’Orbigny, 1841 Hemiliostraca auricincta (Abbott, 1958) Melanella conoidea (Kurtz & Stimpson, 1851) Melanella eburnea (Mühlfeld, 1824) Melanella polita (Linnaeus, 1758) Modulus modulus (Linné, 1758)* x x x x x x x x x x x x x x Caecum pulchellum (Stimpson, 1851) Meioceras nitidum (Stimpson, 1851) Bostrycapulus aculeatus (Gmelin, 1791)* Crepidula depressa (Say, 1822) Crepidula navícula (Mörch, 1877) Cassis flammea (Linnaeus, 1758) Cassis tuberosa (Linnaeus, 1758) Charonia variegata (Lamarck, 1816) Natica lívida (Pfeiffer, 1840) Naticarius canrena (Linné, 1758)* Polinices lacteus (Guilding, 1854) Polinices uberinus (d’Orbigny, 1842) Tectonatica pusila (Say, 1822) Cymatium femorale (Linnaeus, 1758) Rissoinacancellina (Rolán Garcés, 2010) Rissoina multicostata (C.B. Adams, 1850) Lobatus costatus (Gmelin, 1791)* Lobatus gigas (Linnaeus, 1758) Lobatus raninus (Gmelin, 1791) Niveria quadripunctata (Gray, 1827) Pusula pediculus (Linné, 1758) Xenophora conchyliophora (Born, 1780) x x x x x x x x x x Columbella mercatoria (Linnaeus, 1758)* Costoanachis sparsa (Reeve, 1859) Zafrona pulchella (Blainville, 1829) Conasprella jaspidea (Gmelin, 1791)* Gibberula lavalleeana (d’Orbigny, 1842) Granulina ovuliformis (d’Orbigny, 1841) Persicula aff. fluctuata (C.B. Adams, 1850 Fasciolaria tulipa (Linnaeus, 1758) Leucozonia nassa (Gmelin, 1791) Polygona infundibula (Gmelin, 1791) Hyalina pallida (Linnaeus, 1758) Prunum apicinum (Menke, 1828)* Prunum batabanoensis (Espinosa & Ortea, 2002) Prunum caneli (Ortea &Espinosa, 2007) x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x 872 17 Distinción taxonómica de los moluscos del Golfo de Batabanó, Cuba Continuación Taxa Clase Bivalvia Mitridae Muricidae Nassariidae Olivellidae Pseudomelatomidae Raphitominae Allogastropoda Pyramidellidae Cephalaspidea Bullidae Haminoeoidae Cylichnidae Clase Scaphopoda Dentaliida Dentaliidae Gadilida Gadilidae Prunum guttatum (Dillwyn, 1817) Mitra nodulosa (Gmelin, 1791) Chicoreus brevifrons (Lamarck, 1822) Chicoreus florifer (Reeve, 1855) Chicoreus spectrum (Reeve, 1846) Coralliophila salebrosa (H. &A. Adams, 1863) Phyllonotus pomum (Gmelin 1791)* Vasula deltoidea (Lamarck, 1822) Vokesimurex rubidus (Baker, 1897) Nassarius albus (Say, 1822)* Olivella dealbata (Reeve, 1850) Olivella nivea (Gmelin, 1791) Crassispira fuscescens (Reeve, 1843) Pilsbryspira leucocyma (Dall, 1889) Daphnella lymneiformis (Kierner, 1840) 1981-1985 x x x Año(s) 2004 2007 x x x x x x x x x x x x Triptychus niveus Mörch, 1875 Turbonilla interrupta (Totten, 1835) x x Bulla striata Bruguière, 1792* Haminoea antillarum (d’Orbigny, 1841) Haminoea elegans (Gray, 1825) Acteocina candei (d’Orbigny, 1842) Cylichnella bidentata (d´Orbigny, 1842) x Antalis antillaris (d’Orbigny, 1842)* x Polyschides teraschistus (Watson, 1879) x x x x x x x x x x x x x x Lat. Am. J. Aquat. Res., 43(5): 873-887, 2015 Estrategia Ramsar en humedales costeros mexicanos DOI: 10.3856/vol43-issue5-fulltext-7 873 xxx Research Article Implementación del plan estratégico Ramsar en humedales costeros de la Península de Yucatán: normativas y regulación 1 Laura Vidal1, Adriana Vallarino2, Ileana Benítez3 & Jorge Correa3 UMDI, Facultad de Ciencias, UNAM, Puerto de Abrigo S/N, CP 97356 Sisal, Yucatán México 2 El Colegio de la Frontera Sur (ECOSUR), Av. Rancho Polígono 2-A Col. Ciudad Industrial, Lerma Campeche, Campeche, C.P. 24500, México 3 El Colegio de la Frontera Sur (ECOSUR), Ave. Centenario km 5.5, Chetumal Quintana Roo, C.P.77014, México Corresponding author: Laura Vidal ([email protected]) RESUMEN. Se analiza la forma en que México aplica la normativa y otras estrategias de manejo, para la protección de los humedales costeros y aves de humedal de la Península de Yucatán según el Plan Estratégico Ramsar 2009-2015, específicamente en dos de sus estrategias. Se analiza los criterios de regulación de los Programas de Manejo de Áreas Naturales Protegidas y Ordenamientos Ecológicos Territoriales identificando los aspectos científicos robustos en los que se fundamentan, así como en sus deficiencias bajo el concepto de integridad ecológica. En los resultados se observa: a) la necesidad de homogenizar el uso del término integridad en los instrumentos legales, b) crear una estructura jerárquica espacial de estrategias de manejo que favorezca la conectividad, c) reforzar en la delimitación de áreas de amortiguamiento de humedales y hábitats críticos de aves, d) incorporar reglas que protejan la heterogeneidad biológica espacio-temporal, los procesos ecológicos y las redes tróficas, y e) diseñar un reglamento para la restauración de humedales. Se concluye que el escenario normativo aplicable a la conservación de estos ecosistemas en México es aún muy ineficiente y que es necesario incorporar una visión sistémica para proteger estos ecosistemas. Se incluyen además, nueve recomendaciones para su mejoramiento. Palabras clave: normatividad, humedales costeros, aves de humedal, Ramsar, Península de Yucatán. Implementation of the Ramsar strategic plan in coastal wetlands of the Península de Yucatán: regulations and normativity ABSTRACT. The way how Mexico applies the normative and other management strategies, regarding coastal wetland and wetlands birds conservation of the Península de Yucatán following the Ramsar Strategic Plan 20092015 is analyzed. Regulatory criteria within Management Programs of Natural Protected Areas and Ecologic Ordinance Instruments were analyzed identifying strengths and weaknesses under an ecological integrity concept. Results show the need to homogenize the concept of integrity within regulation, to develop a hierarchical spatial structure for management strategies. It will: a) promotes connectivity, b) strength the perception of buffer zones and critical habitats, c) emphasize in the protection of biologic heterogeneity in space and time, ecological processes and trophic networks and, develop regulation about wetland restoration. We conclude that current normative framework is still very inefficient and a systemic vision is required to protect these ecosystems. Nine suggestions to improve the current scenario are included. Keywords: regulations, coastal wetlands, wetlands birds, Ramsar, Yucatán Peninsula. INTRODUCCIÓN Los humedales costeros poseen reconocimiento internacional por su extensión, variedad, importancia biogeográfica y amplia gama de bienes y servicios ambientales tales como retención de nutrientes, almace__________________ Corresponding editor: Sergio Palma namiento y purificación de agua, protección contra tormentas y huracanes (Hiraishi & Harada, 2003; Dahdouh-Guebas et al., 2005), mitigación de crecidas hídricas, estabilización de costas y control de erosión (Millennium-Ecosystem-Assessment, 2005). En 1975 el reconocimiento de su importancia generó la creación 874 xxx Latin American Journal of Aquatic Research de la Convención Relativa a los Humedales de Importancia Internacional (Ramsar) que enfatizó su valor como hábitats de aves acuáticas. En México la Convención Ramsar entró en vigor el 4 de noviembre de 1986 y bajo este compromiso se han designado 142 humedales con una superficie total de casi nueve millones de hectáreas en el territorio idóneas para ser incluidas en la Lista de Humedales de Importancia Internacional (CONANP, 2010). En la Península de Yucatán (PY) existen 23 sitios Ramsar, de los cuales 18 son humedales costeros tropicales con comunidades con manglar reconocidos nacionalmente por ser Regiones Hidrológicas Prioritarias y Áreas de Importancia para la Conservación de las Aves (AICAS) (Arizmendi & Márquez, 2000; CONABIO, 2009, 2010b, 2010a). Este tipo de humedales corresponde al 67% de los sitios Ramsar del país en la región del Golfo de México y a aproximadamente el 30% de los sitios Ramsar de la zona tropical caribeña, que junto con los arrecifes, son relevantes por la diversidad de servicios ambientales que proveen, amplia biodiversidad y endemismo. Se ha estimado que una población de 1.200 millones de aves migratorias utiliza estos humedales en la PY como zona de refugio, alimentación, anidación, crianza y descanso debido a la calidad del agua y gradientes de profundidad (MacKinnon, 2005; Correa-Sandoval & Contreras-Balderas, 2008). Estas aves pueden estar adaptadas a un amplio espectro de humedales (desde las aguas relativamente someras hasta los terrenos simplemente húmedos) de manera “obligada”, “facultativa” y “oportunista” (Weller, 1999) y su presencia ha sido determinante para el diseño y establecimiento de Áreas Naturales Protegidas (ANP) en la región. El proteger algunas colonias de estas aves por su unicidad, estado de amenaza, endemismo o como especies bandera o sombrilla (conceptos descritos por Roberge & Angelstam, 2004) ha favorecido la conservación de otras especies menos llamativas, ecológicamente no menos importantes o coexistentes con ellas en estos ecosistemas (BerlangaCano et al., 2000; Correa-Sandoval et al., 2000). Dada la naturaleza carismática de estas aves, en el país se ha generado una creciente demanda de usos turísticos para su avistamiento como una alternativa productiva para pobladores locales colindantes con humedales costeros. Siendo México signatario de la Convención Ramsar, está comprometido a seguir los lineamientos del Plan Estratégico para 2009-2015 (RAMSAR, 2008). En ellos se enfatiza la responsabilidad de cada país para evaluar sus necesidades de capacitación y formación con respecto a la aplicación de los mecanismos de política, legislación y gobierno institucional, y a fundamentar las estrategias de manejo sobre una base científica. Entre los mecanismos legislativos que se han diseñado para proteger a los humedales y manglares en México, destacan en orden cronológico: 1) Reglamento de la Ley de Aguas Nacionales que incorporó la definición de humedal en 1994 (DOF, 2011); 2) Ley General de Vida Silvestre, creada en julio 2000, que protege manglares pero no humedales en general, con la adición del Art. 60 Ter en febrero de 2007 (DOF, 2014a); 3) Norma Oficial Mexicana NOM022-SEMARNAT-2003 diseñada particularmente para proteger humedales costeros en zonas de manglar (DOF, 2004) y, 4) Ley de Aguas Nacionales que incorporó la definición de humedal en 2004 (DOF, 2013). Además, existen dos instrumentos de política ambiental definidos en la Ley General del Equilibrio Ecológico y la Protección al Ambiente (LGEEPA) (DOF, 2014b) que regulan el uso de suelo y las actividades que impactan negativa o positivamente el equilibrio ecológico y protegen indirectamente a los humedales. Estos instrumentos son: el establecimiento de ANP y la formulación del Ordenamiento Ecológico del Territorio (OET). En la Península de Yucatán, ambas estrategias de manejo (ANP y OET) coinciden geográficamente algunas veces. Pese a estos avances, existen cuestionamientos sobre los escasos y aislados logros respecto a la protección de los humedales costeros mexicanos (Azuela et al., 2008). Se ha cuestionado la eficiencia (grado de idoneidad que posee una norma jurídica para satisfacer la necesidad que se tuvo en cuenta al expedirla) y la eficacia (grado de acatamiento de una norma jurídica por quienes son sus destinatarios) de la legislación aplicable a tal materia basado en lo siguiente: a) todas las especies de manglar en el área (Rhizophora mangle, Laguncularia racemosa, Avicennia germinans y Conocarpus erectus) y varias especies de aves de humedal, algunas de ellas endémicas, están listadas como especies que requieren de protección especial o en alguna categoría de riesgo en la Norma Oficial Mexicana NOM-059SEMARNAT-2010 (DOF, 2010), en la lista de especies en riesgo de la Unión Internacional para la Conservación de la Naturaleza (UICN) o por la Convención sobre el Comercio Internacional de Especies Amenazadas de Flora y Fauna Silvestres (CITES) (CONABIO, 2010a); b) diversos hábitats en los humedales costeros de la PY de importancia crucial para la reproducción y alimentación de aves de humedal, han sufrido continua destrucción y severas modificaciones debido a cambios de uso de suelo, aprovechamiento descontrolado de recursos forestales y acuáticos, introducción de especies florísticas y faunísticas, incendios, contaminación y disminución de los flujos hídricos en los sistemas (Programas de Estrategia Ramsar en humedales costeros mexicanos manejo de ANP en la región-PM), y c) se ha estimado una tasa de pérdida de manglar anual de 1,8 a 3,2% para los tres estados de la Península utilizando fotografías aéreas (Batllori-Sampedro et al., 1999) e imágenes satelitales (INE, 2005). Algunos autores consideran que dada la ausencia de un instrumento de gestión ambiental nacional eficiente para temas prioritarios de conservación de estos ecosistemas y dadas las claras limitaciones de los alcances de las estrategias de gestión aisladas, es necesario construir mecanismos de coordinación administrativa y la armonización de políticas que hagan posible su complementariedad (Rivera-Arriaga & Villalobos, 2001; Carrillo, 2007). También se considera necesario evaluar la capacidad de gestión ambiental para identificar los planos de referencia que se consideran prioritarios en el manejo de este tema ambiental (Vidal, 2010). En consecuencia, este estudio tiene por objetivo identificar cómo México aborda las recomendaciones de gobierno del Plan Estratégico 2009-2015 Ramsar en la zona costera de la Península de Yucatán. Esto, particularmente a través del análisis de coincidencias, vacíos y contradicciones entre los instrumentos legislativos y a través de identificar los aspectos científicos en los que se fundamentan los criterios de regulación en dos de sus instrumentos de política ambiental, recurriendo al concepto de “integridad ecológica”. Esta información será de utilidad para quienes toman decisiones y son responsables de la elaboración y evaluación de estrategias de manejo de humedales costeros (y de algunos de los recursos faunísticos) de la Península de Yucatán, y será el primer paso para realizar una revisión nacional comprensiva sobre el marco jurídico que promueve la conservación y uso racional de los humedales en México, en atención a sus compromisos internacionales ambientales. MATERIALES Y MÉTODOS En seguimiento a dos de las estrategias del Plan Estratégico 2009-2015 Ramsar: a) diseño y evaluación de las necesidades de capacitación y formación en relación a la aplicación de estrategias normativas y, b) manejo de los humedales sobre una base científica, se analizaron los instrumentos legales aplicables a los humedales costeros con manglar de la Península de Yucatán, México. En la Península de Yucatán existen 18 sitios Ramsar que son humedales costeros con comunidades con manglar (asociaciones de mangle con tular, carrizal y petenes), que totalizan una extensión aproximada de un millón de hectáreas. Estos humedales costeros se 875 xxx alimentan de agua marina del Golfo de México y del Mar Caribe, y de aguas dulces continentales por afluentes superficiales importantes como los ríos Palizada, Chumpan, Mamantel, Candelaria, Champotón y Hondo en su parte sur-poniente y sur, y por descargas subterráneas a lo largo del resto de la costa dada la naturaleza cárstica del terreno (Tabla 1). Estrategia “a” El análisis de los mecanismos de legislación nacional respecto a la protección de humedales con manglar (estrategia a) se abordó en dos niveles. Como primer nivel, se estudió el uso del concepto de integridad ecológica en instrumentos legales ambientales de aplicación general en cualquier sitio del país. Entendida la integridad ecológica como la condición bajo la cual un sistema natural se auto-sostiene y auto-regula (Parrish et al., 2003). El concepto de integridad ecológica incluye: a) cadenas alimenticias completas con diversidad en todos los niveles tróficos (Young et al., 2010); b) especies nativas con poblaciones sanas (Parrish et al., 2003); c) procesos ecológicos naturales (flujos de nutrientes, de energía y de elementos funcionales) completos y sin alteraciones extremas (Guzy et al., 2012); d) composición y estructura florística y faunística estables (Cafaro & Primack, 2001); e) resiliencia, auto-recuperación (Hodgson et al., 2009); f) heterogeneidad espacio-temporal de ecosistemas y hábitats (Rasouli et al., 2012); g) balance físico y químico de sedimento y agua (Voss et al., 2012); h) balance de hidroperiodo (Davenport et al., 2010); i) productividad primaria y secundaria constantes (Taylor et al., 1993); j) degradación de materia orgánica constante (Fahring & Merriam, 1985) y k) conectividad, esto es, continuidad estructural y funcional en el espacio y en el tiempo, dispersión y flujo (Lopez-Duarte et al., 2012). Como segundo nivel, se identificó las deficiencias de las estrategias normativas encontradas en los instrumentos de política ambiental (OETs y ANP) de aplicación regional y local en tres estados de la Península (Campeche, Yucatán y Quintana Roo), bajo competencia de los tres órdenes de gobierno (Federal, Estatal y Municipal). Por una parte, de los modelos de OET que contienen Unidades de Gestión Ambiental (UGA) en zonas con manglares, se caracterizaron los criterios de regulación ecológica sobre humedales y aves de humedal en sus diferentes escalas de aplicación (Marino Regional, Regional Estatal (Costero) y Municipal (Local) (Figs. 1, 2). Se consideraron OET en varios momentos de su elaboración y decreto: de revisión (OE Municipales de Campeche: Calkini, Hecelchakan, Tenabo, Carmen, Palizada y el Estatal costero de Campeche), publicados (OE Municipal de Benito Juárez, de la región Corredor 876 xxx Latin American Journal of Aquatic Research Tabla 1. Características de los humedales de manglar en la Península de Yucatán enlistados como Sitios Ramsar, Regiones Hidrobiológicas prioritarias y Áreas de Importancia para la conservación de las aves (AICAS). En el nombre de cada área se indica entre paréntesis su superficie. APF-F: área de protección de flora y fauna, RB: reserva de la biósfera, RE: reserva ecológica. Estado Nombre y características Especie de aves bandera, sombrilla o de interés particular Campeche APF-F. Laguna de Términos (705.016 ha) Región de tres sistemas fluvio-lagunares que constituyen los humedales más importantes de Mesoamérica, con 127.000 ha de manglares. Sitio con las colonias de aves acuáticas de mayor tamaño en Mesoamérica. RB Los Petenes (857 ha) Comunidad de petenes (islotes de vegetación temporalmente inundados o bosques de manglar asociados a manantiales de agua subterránea y cenotes), pastos marinos y comunidades forestales de manglar botoncillo (C. erectus) y palo de Campeche (Haematoxilon campechanum). Áreas de lodos blanquizales. Yucatán RB Ría Celestún (81.482 ha) Comunidades de manglares, camas de pastos marinos, pequeños estuarios, dunas costeras, lagunas costeras hipersalinas, cuevas cársticas que propor cionan hábitat para especies de plantas y animales amenazadas y raras. Sitio de anidación de tortugas marinas, de descanso y alimentación para especies de aves migratorias y de colonias reproductoras de garzas. RE El Palmar (50.177 ha) Comunidades de manglares, camas de pastos marinos, llanuras de marea, dunas costeras, petenes, cenotes, bosques de pantano y bosques deciduos; zona de alimentación de patos, flamencos y de anidación de tortugas marinas. Jabiru (Jabiru mycteria), gaitán (Mycteria americana), cocopato (Eudocimus albus), garza blanca (Ardea alba), pichiche (Dendrogygna autumnalis). Jabiru (Jabiru mycteria), flamenco (Phoenicopterus ruber), garza tigre (Tigrisoma mexicanum), cerceta de alas azules (Anas discors), candelero (Himantopus mexicanus). Flamenco (Phoenicopterus ruber), garza tricolor (Egretta tricolor), garza blanca (Ardea alba). Flamenco (Phoenicopterus ruber), cerceta alas azules (Anas discors), pelícano alcatrás (Pelecanus erythrorynchos), garza melenuda (Egretta rufescens). RE Dzilam (61.707 ha) Reserva marina-costera con sistema hidrológico único llamado “anillo de cenotes” causado por el impacto de un meteorito. Pastos marinos, lagunas intermareales, dunas costeras, selva inundada, selva mediana y selva baja. Hábitat de más de 20.000 aves acuáticas. Flamenco (Phoenicopterus ruber), boxpato (Cairina moschata), anhinga (Anhinga anhinga). RB Ría Lagartos (60.348 ha) Sistema complejo de pequeños estuarios y lagunas costeras hipersalinas separadas por el mar de un cordón de dunas. Con influjo de algunos acuíferos subterráneos. Hábitat de variadas especies de fauna y flora amenazadas o en peligro. Flamenco (Phoenicopterus ruber), jabirú (Jabiru mycteria), camacho (Phalacrocorax auritus), garza kuka (Cochlearius cochlearius), chorlo silbador (Charadrius alexandrinus), playero occidental (Calidris mauri), playero mínimo (C. minutilla). Quintana Roo APF-F Yum Balam (154.052 ha) Lagunas costera con selva baja y mediana, manglares y petenes, Comunidades de palmas tasiste (Acoelorraphe wrightii). APF-F Manglares de Nichupté (4.257 ha) Comunidades densas de manglares en bandas (R. mangle, A. germinans, C. erectus, Laguncularia racemosa) que ofrecen protección a la costa y zonas de palmeras en condición de amenaza (Thrinax radiata). Con ruinas arqueológicas mayas. Flamenco (Phoenicopterus ruber), garza melenuda (Egretta rufescens), morfo blanco del garzón cenizo (Ardea herodias), chocolatera (Platalea ajaja). Rascón picudo (Rallus longirostris). RB Sian Ka’an (528.147 ha) Sitio Patrimonio de la Humanidad UNESCO Planicie costera cárstica, paralela a una barrera arrecifal de 120 km, con dos bahías someras rodeadas de manglares. Con numerosos cenotes inmersos en una selva tropical decidua. Comunidades endémicas de bosque de pantano y petenes. Hábitat de 320 especies. Pelícano café (Pelecanus occidentalis), camacho (Phalacrocorax auritus), garza blanca (Ardea alba), garza kuká (Cochlearius cochlearius), garza tigre (Tigrisonma mexicanum), cocopato (Eudocimus albus), chocolatera (Platalea ajaja). Estrategia Ramsar en humedales costeros mexicanos 877 xxx indicadores de sustentabilidad institucional (Tabla 2), como también en el manual Ramsar para examinar leyes e instituciones orientadas a promover la conservación y el uso racional de los humedales (RAMSAR, 2010). Estrategia “b” La estrategia “b” analiza la pertinencia de los criterios de regulación ecológica expresados en los OET y en los PM de la ANP para las zonas de humedal en base en una recopilación bibliográfica de la información científica que caracteriza ecológicamente las zonas habitadas por diversas familias de aves de humedal (hábitat, depredadores, alimento y principales amenazas). Se emplearon como referencias las compilaciones de Weller (1999), Perlo (2006), Llamosa (2011), Badillo et al. (2014) y del Cornell Lab of Ornithology (2010). RESULTADOS Figura 1. Humedales costeros de la Península de Yucatán donde confluyen Áreas Naturales Protegidas y Ordenamientos Ecológicos del Territorio. Fuente: modificado de mapa de ANP de CONANP. Cancún-Tulum, de región Costa Maya, de la región de Sian Ka´an, Territorial de Quintana Roo, Estatal costero de Yucatán (POETCY) y OE Marino Regional del Golfo de México y Mar Caribe (GoM y MC). Por otra parte, se identificaron las ANP de la PY con humedales costeros cuyos hábitat destacan por su importancia ecológica para aves de humedal, que son consideradas sitios Ramsar y que poseen PM vigentes (Laguna de Términos 1997, Río Lagartos 2000, Ría Celestún 2002, Dzilam 2006 y Los Petenes 2009). Se identificaron las reglas administrativas referentes a la protección y aprovechamiento de humedales y aves de humedal de manera explícita y se separaron en dos secciones para facilitar su análisis: a) acciones que se permiten o promueven y b) acciones que son prohibidas. Para caracterizar las reglas administrativas o criterios de regulación ecológica se emplearon cinco apartados temáticos relevantes a la preservación o impacto en estos recursos naturales: a) caminos y vialidades, b) flujos hídricos, c) fauna y flora silvestre, d) construcción y urbanización, y e) aprovechamiento de humedales. Posteriormente, cada aspecto de regulación ecológica se categorizó según los criterios utilizados para evaluar la capacidad de gestión ambiental compilados por Vidal (2010), basados en Estrategia “a” En el análisis de los mecanismos de legislación a escala nacional en relación a la protección de humedales con manglares, se observaron varias inconsistencias: a) a través de los ecosistemas que protegen (humedales, humedales costeros o manglares); y b) a través del uso del concepto de integridad. Mientras la NOM-022SEMARNAT-2003 establece las especificaciones para garantizar la integridad de los humedales costeros en zonas de manglar, el Art. 60 Ter de la LGVS prohíbe la ejecución de cualquier obra o actividad que afecte la integralidad de sus procesos y servicios ecológicos. Es decir, se utilizan dos términos gramaticalmente distintos "íntegro" e "integral", que podrían interpretarse con ambigüedad jurídica para dar protección legal a los humedales. La presencia temática de aspectos relevantes a la preservación o impacto en humedales y aves de humedal entre los criterios de regulación ecológica de los OET en los tres niveles espaciales (Marino Regional, Estatal Costero y Municipal) y las reglas de Programas de Manejo (PM) de ANP en zonas con manglares (Tabla 3) muestran que no existe una estructura jerárquica o anidada de estrategias de manejo a diferentes escalas. Parece que cada instrumento se ha diseñado sin consideración de las especificaciones de sus predecesores, los que se sobreponen geográficamente y fueron diseñados en otra escala espacial. Además, se observa que, aún en escala regional, sólo se hace particular énfasis en aspectos de regulación ecológica a pequeña escala: como impulsar programas de recuperación de especies enlistadas en la NOM-059SEMARNAT-2001 e implementar programas (o campañas) de reforestación y recuperación en los márgenes de ríos (manglares y humedales ribereños). 878 xxx Latin American Journal of Aquatic Research Figura 2. Jerarquía en el marco jurídico y político sobre la protección y aprovechamiento del ambiente y recursos naturales en México. ANP: Áreas Naturales Protegidas, OET: Ordenamientos Ecológicos del Territorio. Tabla 2. Criterios para evaluar la capacidad de gestión ambiental según su plano de referencia modificada por Vidal (2010). Criterios para evaluar capacidad de Gestión Ambiental Político-administrativos 1. Políticas de regulación y manejo. 2. Nivel de prioridad que el gobierno otorga a la protección del ambiente (financiamiento). 3. Viabilidad institucional (proyectos y programas a largo plazo y competencia institucional). 4. Calidad de la información disponible sobre causas de estrés ambiental y tasas de uso y deterioro ambiental (monitoreo), como también uso de información para planificación y mitigación. 5. Nivel de conocimiento y entrenamiento técnico de los manejadores (staff). 6. Recomendaciones técnicas, generalmente con respecto a infraestructura. Normativos 7. Existencia de un régimen de regulación que determine necesidades ambientales (presencia de instrumentos de política ambiental o de procedimientos administrativos para aplicar tal régimen). Sociales 8. Incorporación de factores socioculturales locales en el manejo y la planificación de los recursos. A escala estatal y municipal, los OE del estado de Quintana Roo poseen el mayor número de criterios de regulación en comparación con los otros estados. Sin embargo, aún para este estado existe un vacío en la elaboración de un instrumento costero general que favorezca una visión de continuidad ecológica. En algunos casos hay, además, criterios de regulación contradictorios sobre el aprovechamiento de los humedales o del corte de árboles de mangle en zonas adyacentes a la misma costa (e.g., áreas de manglar no podrán utilizarse para ninguna actividad productiva en el área de un OET mientras su aprovechamiento sí está permitido en un área colindante de otro OET, siempre que no exceda el 10% de la cobertura de mangle incluida en el predio, o mientras se sujete a los lineamientos del programa de manejo de la ANP). Por una parte, entre los criterios de regulación analizados en los OET, los aspectos de integridad ecológica que están presentes son: especies nativas sanas, conectividad y balance de hidroperiodo. Los bienes ambientales que se procura conservar, aunque escuetamente (15% de los criterios de regulación), son los flujos hídricos y la calidad del agua. Por otra parte, entre los PM de ANP se puede apreciar que el de Laguna de Términos contiene el mayor número de reglas de control con respecto a humedales y aves de humedal (12) y contempla tres de los cinco grupos temáticos analizados. El caso opuesto lo presenta el PM de Los Petenes, de reciente creación (2009) y estrechamente vinculado con Ría Celestún, cuyo PM es aún muy limitado en alcances. Los programas de manejo de las ANP revisados fueron dise- Tabla 3. Presencia temática en criterios de regulación y reglas de control de los Ordenamientos Ecológicos Territoriales (OE) y Programas de Manejo (PM) de ANP sobre humedales costeros y aves de humedal en la Península de Yucatán. GM: Golfo de México, MC: Mar Caribe. El símbolo √ señala que en ese instrumento el criterio o regla estaba presente. Estrategia Ramsar en humedales costeros mexicanos 879 xxx 880 xxx Latin American Journal of Aquatic Research ñados entre 1996-2009, y solo el de Laguna de Términos se encuentra en proceso de actualización. Cada PM tiene siete reglas que no parecen seguir un patrón particular. Mientras que algunos aspectos de integridad ecológica son muy repetidos entre los PM, otros simplemente no se consideran o lo hacen de manera muy limitada. Entre las reglas administrativas restrictivas explícitas sobre humedales o aves en los PM analizados, la mayoría están enfocadas a evitar: la introducción de especies alóctonas, la alteración de sitios de anidación y de reproducción, la perturbación de organismos silvestres y extracción de partes, la destrucción y aprovechamiento de especies de flora y fauna enlistadas como en categoría de riesgo (que incluyen los manglares) o en zonas núcleo y la modificación de flujos naturales y desecación de humedales. Las reglas propositivas incluyen: controles de navegación (velocidad, distancia de acercamiento a sitios con flamencos y uso de remos en zonas someras), permanencia de visitantes en sitios con fauna silvestre, manejo controlado de fauna silvestre para autoconsumo (principalmente) y establecimiento de la obligación de evitar ejercer presión (aquí empleado como estresor), a especies silvestres que se encuentren bajo alguna categoría de protección. Es decir, se vinculan solamente con dos aspectos de integridad ecológica: especies nativas sanas y balance de hidroperiodo. Entre ambos instrumentos, algunos aspectos de heterogeneidad de hábitats (áreas de anidación y reproducción), composición florística (reforestación, extracción forestal y recuperación de manglares) y balance físico y químico del agua (descargas de aguas residuales domésticas e industriales) se retoman marginalmente entre los criterios de regulación. Estrategia “b” La información científica que caracteriza ecológicamente a las 16 familias de aves de humedal más abundantes de la Península de Yucatán y que sustenta las reglas contenidas en los OET y los PM (Tabla 4, constituye además una selección de un total de 29 familias, para representar en forma más definida diferentes tipos de nichos ecológicos con respecto a alimentos, sitios de reproducción y depredadores. En relación a la presencia de los planos de referencia de gestión ambiental sobre la conservación de aves de humedal o humedales entre los criterios de regulación de los OET (Fig. 3) se observa una ausencia total de reglas sobre financiamiento y capacitación de personal y únicamente un caso para aspectos sociales (educación ambiental). En cambio, hay una mayor abundancia de reglas que necesitan información y monitoreo científico para ser aplicables (36%). Esta condición hace nece- sario evitar ciertas conductas basándose solamente en instrumentos normativos (leyes, reglamentos y NOMs), en procedimientos administrativos (Evaluación del Impacto Ambiental, diseños de zonas de exclusión o regulaciones del uso de suelo) y en prohibiciones explícitas (33%). DISCUSIÓN México, ante el compromiso internacional de haber firmado la convención Ramsar para conservar sus humedales, ha tenido importantes avances de gestión reconocidos internacionalmente durante la COP12 en junio 2015 en Uruguay. Entre ellos destacan: la elaboración (en proceso) del Inventario Nacional de Humedales; la implementación de la Estrategia Mexicana de Comunicación, Educación, Concienciación y Participación en Humedales (CECoP) 2010-2015; el impulso de crear una Norma Mexicana de Caudal Ecológico y el Programa Nacional de Reservas de Agua; y recientemente la formulación y lanzamiento de la Política Nacional de Humedales (Informe Nacional de México a la COP12 de Ramsar 2015). Sin embargo, a nivel operativo aún hace falta reforzar la congruencia entre los instrumentos legales aquí analizados y se requiere elaborar estrategias de manejo a escala regional. Estrategia “a” Algunas reformas recientes a la LGEEPA (mayo 2013) han logrado avances que refuerzan lo expresado en los lineamientos de las ANP. Por ejemplo, la introducción de especies exóticas invasoras en ANP, prohibida tajantemente (Art. 46) y el control de tráfico de embarcaciones en zonas marinas, limitado de acuerdo con el PM (Art. 48). Sin embargo, aún hay aspectos contradictorios, como por ejemplo: la desecación de humedales es permitida por la LAN, ya sea con fines de protección o para prevenir daños a la salud pública, mientras que entre las reglas administrativas de los PM esta misma acción se restringe. Por un lado, el uso indistinto de integro e integral en referencia al concepto de integridad ecológica en los instrumentos de legislación revisados en la estrategia “a” hace suponer que el término “daño a la integralidad del manglar” podría ser insuficiente para proteger manglares expeditamente. Esto es, por jerarquía de leyes en el Derecho Mexicano, una Ley General expedida por el Congreso de la Unión, como lo es la LGVS, tiene mayor rango y debe aplicarse por encima de una NOM, que en caso de contradicción, se aplicaría el término de “integralidad” determinado en la Ley General que es un término que no aparece en el diccionario de la Real Academia de la Lengua Española. 881 xxx Estrategia Ramsar en humedales costeros mexicanos Tabla 4. Caracterización ecológica de familias de aves acuáticas (Weller, 1999) que habitan en mayor abundancia los humedales costeros de la Península de Yucatán. Elaboración propia. *Sensibles a contaminantes. Orden taxonómico y nomenclatura de acuerdo a Chesser et al. (2010). Familia/especies en riesgo Alimento Hábitat de reproducción Depredadores Anatidae: Cairina moschata, Nomonix dominicus, Anas discors Phoenicopteridae: Phoenicopterus ruber Ciconiidae: Jabiru mycteria y Mycteria americana *Phalacrocoracidae: Phalacrocorax auritus, P. brasilianus *Anhingidae: Anhinga anhinga *Pelecanidae: Pelecanus occidentalis, Ardeidae: E. rufescens, Ardea alba, Ixobrychus exilis, Tigrisoma mexicanum, Cochlearius cochlearius, Threskiornithidae: Eudocimus albus, Platalea ajaja *Pandionidae: Pandion haliaetus Charadriidae: Charadrius alexandrinus, C. wilsonia, C. melodus Haematopodidae: Haematopus palliatus Recurvirostridae: Himantopus mexicanus, Recurvirostra americana Jacanidae: Jacana spinosa Plantas acuáticas, insectos, peces, plancton, crustáceos, frutos, Artrópodos, algas Crustáceos, materia orgánica Peces, anfibios, crustáceos, reptiles, aves, insectos Peces Pastos, raíces, vegetación variada Cocodrilos, mapaches, perros ferales, ratas, gavilanes Bajos de lodo y arena Árboles y arbustos Mapaches, perros ferales, jaguares Cocodrilos Árboles y arbustos Gaviotas, fragatas, iguanas. Peces Peces Árboles Árboles y arbustos Gaviotas, fragatas, iguanas. Gaviotas, fragatas, iguanas. Peces, crustáceos, pequeños anfibios, insectos Árboles y arbustos Tlacuaches, ratas, nutrias, urracas, gavilanes, halcones, iguanas y serpientes Peces, crustáceos, anfibios, insectos Peces Árboles y arbustos Gaviotas, fragatas, iguanas Copas de árboles Halcones Scolopacidae: Tringa flavipes, Calidris alba, C. mauri, C. minutilla Laridae: Leucophaeus atricilla, Larus argentatus, Sternulla antillarum Alcedinidae: Megaceryle torquata, M. alcyon, Chloroceryle amazona, C. americana, C. aenea Crustáceos, insectos, lapas, Playa arenosa con guijarros almejas, gusanos, poliquetos o conchas Gaviotas, fragatas, halcones, perros ferales Bivalvos, gusanos, poliquetos. Pequeños crustáceos, materia orgánica, poliquetos Playas con guijarros o conchas Playas arenosas con vegetación rastrera Mapaches, perros ferales, gaviotas Mapaches, perros ferales, gaviotas Vegetales, insectos, gusanos, moluscos Insectos, lapas, almejas, gusanos, poliquetos Vegetación herbácea emergente de agua dulce N/A Cocodrilos, mapaches, perros ferales, ratas, gavilanes N/A Peces Playa arenosa con guijarros o conchas Mapaches, perros ferales, otras gaviotas Peces Huecos en la tierra en la ribera de los cuerpos de agua Serpientes, urracas, iguanas Esta situación podría favorecer posturas en contra de la conservación de manglares en el campo litigioso. Como ejemplo de esto, Connolly (2008) asegura que esta situación de controversia en el campo de la interpretación jurídica por el uso de términos es común en los casos de regulación de humedales costeros en USA. A nivel de instrumentos de política ambiental, ambos (OET y ANP) requieren ser fortalecidos en México, debido a que presentan algunas debilidades evidentes, tal como se observa tanto en los resultados aquí presentados como en los discutidos por Cortina et al. (2007). Este estudio identificó en la caracterización temática de los criterios de regulación un particular én- 882 xxx Latin American Journal of Aquatic Research fasis en aspectos de regulación ecológica con aplicación a pequeña escala, es decir, reforestación y recuperación de especies amenazadas o en riesgo. Cortina et al. (2007) identificaron diversos problemas de carácter institucional y legal para las ANP y OET. Entre los primeros destaca, la ausencia de una definición clara y operativa de la “capacidad de carga del ecosistema” y de las “proporciones y límites de cambio aceptables” conceptos que son, indiscutiblemente, resultado de procesos de investigación científica en aspectos de integralidad ecológica de un ecosistema. Además, esos autores señalan, como ejemplo, las dificultades existentes para controlar la actividad turística en las ANP y las limitaciones para definir la cantidad óptima de visitas, en función del desconocimiento de los impactos ambientales que las actividades ocasionan en los recursos a conservar. Esto claramente es aplicable a la actividad turística de avistamientos de aves en humedales cuando no existe el diseño y aplicación de reglas que eviten costos ambientales indeseables en la integralidad del ecosistema. Además, Cortina et al. (2007) han identificado como problema legal y normativo de los OET locales y regionales el hecho que al estar supeditados a un OET federal del territorio (de mayor escala geográfica), estas disposiciones normativas pierden flexibilidad, y las contribuciones de mayor definición por la visión más detallada de los procesos que éstas representan se diluyen. Por lo tanto, el presente trabajo, con otro enfoque, evidencia la necesidad de conservar una escala regional en los OET cuando se trata de corredores biológicos de ecosistemas; de tal manera que los criterios de regulación, por una parte, no se pierdan en acciones de mínima escala y por otra parte, se reduzca la contradicción en el aprovechamiento o conservación de recursos naturales, como humedales y mangle, compartidos entre zonas adyacentes como ha sido el caso de los OET de Quintana Roo, claramente aquí mencionado. Se entiende que esta variabilidad se debe al momento político en el que cada instrumento se formuló, especialmente en lo referido a las modificaciones realizadas en la NOM-022 en el 2004. Actualmente, sin embargo, la controversia debe resolverse con la adición del Art. 60 Ter en la LGVS en el 2007, siempre y cuando se interprete el afectar la “integralidad” de los procesos y servicios ecológicos como afectar la “integridad”, en el sentido discutido anteriormente. El diseño de estrategias de manejo (planificación y atención de problemas de impacto ambiental) con consideración de escalas espaciales resulta esencial para su éxito; tanto así que actualmente se enfoca mucho esfuerzo en regionalizar las áreas marinas y costeras según sus características ecológicas (Espejel & Bermúdez, 2009). Desde hace dos décadas, Wiens (1989) reconoció que la probabilidad de mantener poblaciones silvestres dinámicas frecuentemente depende de estrategias de manejo a diferentes escalas espaciales. Esta visión es necesaria para la conservación, tanto de los humedales como para las aves de esta región. Especialmente para estas últimas, tanto para especies nativas como migratorias, y no sólo para las nativas como se incluye en los criterios de regulación analizados en los OET. Si bien es conocido que la habilidad de gestionar recursos para manejar efectivamente los humedales es mayor a escalas locales (parques, refugios y áreas de manejo), la escala a la cual el manejo tiene mayor repercusión biológica es mucho mayor (cuencas regionales) (Erwin, 2002; Quoc-Tuan et al., 2012). En este sentido, se debe enfatizar que el aspecto de conservar la conectividad, manifestado en los criterios de regulación analizados, sea en realidad operativo. De tal forma, se esperaría que las recomendaciones de mayor escala espacial favorecerán la conectividad (Hall et al., 2011) entre ANP regionales, resaltarán la conservación de los servicios ambientales de estos sistemas costeros y, si bien darán mayor importancia a las especies nativas regionales, no excluirán a las migratorias, independientemente de si están o no enlistadas en alguna categoría de riesgo. Estas condiciones no se cumplen actualmente en los ordenamientos analizados y ante ello, es necesario mejorarlos. Otro aspecto a destacar entre los criterios administrativos analizados es el tema de la restauración de humedales. Si bien la restauración es considerada una estrategia prioritaria en la Evaluación de los Ecosistemas del Milenio, también es cierto que obedece a diferentes motivaciones y paradigmas (Davenport et al., 2010; Jenkins et al., 2010). Estos van desde el deseo de recuperar ambientes degradados, obtención de beneficios económicos, publicidad e imagen, hasta motivaciones puramente tecnócratas. Por ello, propiciar esta política local o regionalmente, sin cuidado o control adecuados, puede implicar algunos riesgos a la integridad de los sistemas ecológicos (Hobbs et al., 2011; Ma et al., 2011) y a su conectividad. Otra línea potencial de mejora en el diseño de medidas de regulación y, de investigación en estos humedales es el aspecto del balance de hidro-periodo y la calidad del agua. Ambos son cruciales para la presencia de los humedales y si estos no se conservan cabalmente, los servicios ambientales que ofrecen, como aquéllos vinculados a la presencia de aves de humedal y al consecuente uso de éstas con fines turísticos, no será posible. Aunque estos aspectos están presentes en los criterios de regulación de los POET, Estrategia Ramsar en humedales costeros mexicanos profundizar en este tema, aportará más elementos para identificar las amenazas asociadas con la pérdida y degradación de los bienes y servicios ambientales, pero también para reconocer los posibles límites de una eventual regionalización que considere la conectividad entre los ecosistemas. Es importante mencionar que legalmente los PM de ANP pueden ser revisados y actualizados por lo menos cada cinco años (Art. 77 del Reglamento de la LGEEPA en materia de ANP). Asimismo, las reformas de febrero de 2005 y mayo de 2013 a la LGEEPA y su Reglamento en materia de ANP (DOF, 2000) determinaron los diferentes tipos de zonas y subzonas en que pueden dividirse sus territorios, así como las actividades permitidas y prohibidas dentro de cada una de ellas (Art. 47 Bis). Esta zonificación debe observarse de manera obligatoria y, constituye, una oportunidad para que la Comisión Nacional de Áreas Naturales Protegidas (CONANP) promueva la actualización de sus PM, tomando en cuenta la reciente información científica que apoya las acciones de conservación de la integridad y conectividad de los humedales. Estrategia “b” El análisis de las reglas administrativas restrictivas y propositivas sobre humedales o aves en los PM analizados y la información compilada en la Tabla 4 lleva a discutir dos aspectos: primero, que como algunos expertos sugieren, los estudios orientados a las acciones de conservación en estas zonas debieran beneficiar directa y principalmente los hábitats de aves migratorias amenazadas, no cinegéticas, y muchas veces endémicas (e.g., cigüeña jabirú, cigüeña americana, pato golondrino, cerceta aliazul clara, pato chalcuán, pato boludo chico, y martín pescador, listados en la NOM -059, UICN y CITES), más del 80% de las especies de aves de humedal registrados en la zona costera, quedarían desprotegidas. Segundo, hay aspectos de la integralidad ecológica de los humedales y de las aves de humedal ausentes en las reglas de los PM, que es necesario reforzar o incorporar en los instrumentos normativos para asegurar el mínimo impacto y estrés en los mismos. Algunos a reforzar son: dimensiones de las áreas de amortiguamiento para que los manglares no sean afectados por los cambios de flujos hídricos o desmonte y el porcentaje de cobertura forestal que debe ser conservado sin perturbación (Christensen et al., 2008; Quoc-Tuan et al., 2012), como también las distancias mínimas y tiempos máximos de acercamiento a los hábitats de descanso, anidación y alimentación de las aves. Se debe incorporar reglas sobre: la protección de vegetación arbustiva y herbácea asociada a los cuerpos de agua (no solo de árboles); la conservación de la integridad de las 883 xxx raíces de las comunidades forestales; la conservación de la heterogeneidad de comunidades biológicas y el mantenimiento de su conectividad con otros ecosistemas (Luther & Greenberg, 2009; Beger et al., 2010). Todo esto para asegurar el flujo de agua, nutrientes y energía determinantes para la sobrevivencia de aves de humedal (May et al., 2002). Se debe reforzar la aplicación del respeto a la capacidad de carga y límite de cambio aceptable para usos y aprovechamientos dentro de las ANP, tal como lo señalan los Art. 80 y 81 del reglamento de la LGEEPA en materia de ANP. Con respecto a las aves de humedal, es necesario incluir reglas sobre la determinación de áreas mínimas para la reproducción y anidación (aspectos que suelen ser empleados en los procedimientos de EIA); hábitats críticos de las presas y depredadores (aspectos que definen su nicho ecológico, Weller, 1999); control o eliminación de fauna feral y monitoreo, control y vigilancia relacionados con la descarga de contaminantes a los cuales varias familias de aves son muy sensibles (Luther & Greenberg, 2009; Beger et al., 2010). De no efectuarse estas modificaciones, es posible que las estrategias de manejo sean aún muy generales y que no aseguren la integridad de los ecosistemas de humedal. Se sugiere reforzar los mecanismos de participación de expertos para incluir criterios de manejo más precisos en los PM. Además se considera que la información debe ser individualizada por humedal, pero las prioridades de información para regularlos deben estar homogenizadas de manera que el tratamiento o manejo de estas áreas persigan los mismos objetivos y la aplicación normativa se facilite. En particular, esto es relevante para ecosistemas que funcionan como corredores biológicos a escala continental (como todos los humedales costeros de la Península de Yucatán), cuya protección diferenciada podría causar el aislamiento de poblaciones de aves de humedal y la pérdida de continuidad ecológica para aves migratorias. Es decir, aunque la conectividad ecológica se ha tratado de contemplar legalmente, mediante el establecimiento de zonas de amortiguamiento y zonas de influencia en la definición de los polígonos de las ANP, y que las reformas de 2007 a la LGEEPA pretendieron promover la continuidad ecológica de áreas protegidas a través de decretar que los PM sean considerados en la formulación de los OET, es necesario ahondar legal y prácticamente dicha formulación. El análisis de capacidad de gestión ambiental (Fig. 2) permite evidenciar un escaso interés en regular recursos financieros, humanos (con capacitación permanente) y materiales, así como la integración social en el manejo de los recursos naturales. Este 884 xxx Latin American Journal of Aquatic Research último aspecto debilita mucho la posibilidad de hacer eficiente la protección y conservación de recursos naturales. Los avances más notables en la última década en este tema se han logrado empleando estrategias de co-manejo y manejo participativo (es decir, manejo compartido entre usuarios y autoridades), más que diseñando e imponiendo reglas estrictas impuestas por las autoridades. Es necesario reforzar la participación social, la comprensión de las reglas y la confianza de los usuarios aún en caso de tener que aplicar el Principio Precautorio (tomar medidas de control aún con gran incertidumbre de información científica). Se concluye que el enfoque transversal (entre instrumentos) y espacial (a diferentes escalas) empleado en este análisis, permite detectar que el escenario jurídico global aplicable a la conservación de los humedales y aves de humedal de la región PY es aún ineficiente (Brañez, 2004) por las siguientes razones: a) Hay conceptos en sus instrumentos legales como “integralidad” por “integridad” que pueden favorecer la ambigüedad de interpretación jurídica. b) Aún hay ANP y OET sin reglas sobre la protección de los humedales costeros y de las aves de humedal de la PY. c) No existen las normas jurídico-ambientales necesarias para lograr una protección sistémica para que los humedales mantengan la integridad ecológica, particularmente la conectividad, el hidroperiodo con adecuado balance físico y químico, la degradación constante de materia orgánica, procesos ecológicos completos, cadenas alimentarias completas, productividad primaria y secundaria, heterogeneidad espacio-temporal y variedad florística y faunística. d) No existen suficientes elementos científicos sobre las causas de estrés ambiental en humedales y protección de aves en zonas de anidación, reproducción y alimentación, así como sobre los servicios ecológicos que ofrecen los humedales que se reflejen en criterios regulatorios. Recomendaciones para fortalecer las condiciones normativas a) Elaborar compendios de información científica básica necesaria para el diseño de reglas administrativas ad-hoc para cada ANP y sistemas de humedales (a nivel local y regional), pero homogenizando en temas prioritarios que deben regularse. b) Intensificar la investigación sobre nichos ecológicos y requerimientos de hábitats de las aves que habitan c) d) e) f) g) h) i) los humedales de la costa peninsular y reflejar tal información en los PM. Promover el diseño de estrategias y reglas de manejo que favorezcan la integridad de los ecosistemas y la conectividad entre ANP regionales y asegurar así, las medidas para conservar todos los servicios ambientales de estos sistemas costeros. Además, controlar el seguimiento de su aplicación. Procurar el diseño de reglas de manejo que incluyan la protección de diferentes doseles de la vegetación y variedades de hábitats (visión de sistema), de forma que no se espere proteger a las aves de humedal con reglas muy generales. Solicitar a las autoridades competentes en materia ambiental de los tres niveles de gobierno, que consideren una estructura jerárquica o anidada de estrategias de manejo a diferentes escalas espaciales (considerando zonas de amortiguamiento y zonas de influencia), que homogenice criterios y prioridades. De tal forma que, al validar los OET y PM se consideren las estrategias previamente diseñadas y se busque la congruencia y complementariedad entre ellas. Sin duda, la atención a los retos que México aborda en materia de planeación territorial y ecológica podrán ser de utilidad para otros países latinoamericanos, sobre todo para aquellos ecosistemas donde la conectividad es crítica. Diseñar y robustecer mecanismos de consulta a expertos y usuarios de bienes naturales para que participen en la evaluación de estrategias de manejo de recursos naturales en ANP (como el Directorio en línea de especialistas de manglares en México, promovido por la CONABIO como parte del programa “Los Manglares en México: estado actual y establecimiento de un programa de monitoreo a largo plazo”) y crear una base de datos sobre información científica de recursos naturales a nivel regional que pueda se consultada al actualizar PM. Incentivar a los ecólogos a involucrarse en los procesos del manejo de los recursos y ecosistemas naturales y a publicar en medios de difusión accesibles a los tomadores de decisiones. Realizar un análisis comprensivo de políticas públicas y un reglamento acerca de las estrategias de restauración de humedales costeros. Complementar con la evaluación de estrategias institucionales de manejo y conocimientos tradicionales acerca de estas estrategias para abordar los compromisos del Plan Estratégico Ramsar 2009-2015. AGRADECIMIENTOS Los autores agradecen al CONACyT y la Dirección General de Personal Académico (DGAPA) de la UNAM Estrategia Ramsar en humedales costeros mexicanos por su apoyo financiero para realizar estancias posdoctorales durante las cuales se elaboró este trabajo. Los autores agradecen al ICMyL (UNAM) por facilitar el uso del servicio bibliotecario, equipo de cómputo e instalaciones en la estación El Carmen durante la misma estancia posdoctoral. Agradecemos al Biol. Hernán Álvarez Guillén (estación El Carmen ICMyL) por su apoyo logístico en la búsqueda de material bibliográfico empleado en la elaboración de este documento y al M. en C. Imre Páramo por su apoyo en la edición del documento. REFERENCIAS Arizmendi, M.C. & L. Márquez. 2000. 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Watt. 2010. The emergence of biodiversity conflicts from biodiversity impacts: characteristics and management strategies. Biodivers. Conserv., 19: 3973-3990. Lat. Am. J. Aquat. Res., 43(5): 888-894, 2015 DOI: 10.3856/vol43-issue5-fulltext-8 Amino acid requirements of Astyanax fasciatus 888 1 Research Article Estimation of the dietary essential amino acid requirements of colliroja Astyanax fasciatus by using the ideal protein concept Wilson Massamitu Furuya1,2, Mariana Michelato2, Ana Lúcia Salaro3 Thais Pereira da Cruz1 & Valéria Rossetto Barriviera-Furuya1 1 Departamento de Zootecnia, Universidade Estadual de Ponta Grossa Av. Carlos Cavalcanti 4748, 84030-900, Uvaranas, Paraná, Brazil 2 Programa de Pós-Graduação em Zootecnia, Universidade Estaudual de Maringá Av. Colombo 5790, Zona 07, 87030-900, Maringá, Paraná, Brazil 3 Departmento de Biologia, Universidade Federal de Viçosa Avenida Peter Henry Rolfs s/n, Campus Universitário, Viçosa-MG, 36570-000, Brazil Corresponding author: Wilson Massamitu Furuya ([email protected]) ABSTRACT. Colliroja, Astyanax fasciatus, is a new aquaculture species, and information on its dietary essential amino acid requirements is lacking. The whole body composition of 120 farmed fish (16.2 ± 8.8 g) was determined to estimate the dietary essential amino acid requirement based on the ideal protein concept ((each essential amino acid/lysine) ×100), and the findings were correlated to the whole body essential amino acid content of Nile tilapia Oreochromis niloticus. The dietary essential amino acids, including cysteine and tyrosine, accounted for 5.46, 4.62, 1.16, 3.28, 5.63, 2.01, 2.59, 2.84, 4.66, 3.39, 0.65, and 3.51% of the total protein for lysine, arginine, histidine, isoleucine, leucine, methionine, methionine+tyrosine, phenylalanine, phenylalanine+tyrosine, threonine, tryptophan, and valine, respectively. There were positive linear and high correlations (r = 0.971) between the whole body amino acid profiles of colliroja and Nile tilapia. Thus, the whole body amino acid profile of colliroja might be used to estimate accurately the essential amino acid requirement. Keywords: Astyanax fasciatus, amino acids, nutrition, protein, ideal protein concept, aquaculture. Estimación de los requerimientos dietéticos de aminoácidos esenciales de colliroja, Astyanax fasciatus, basadas en el concepto de proteína ideal corporal RESUMEN. Colirroja, Astyanax fasciatus, es una nueva especie de la acuicultura y no hay información sobre sus requerimentos de aminoácidos esenciales en la dieta. Se determinó la composición corporal de 120 peces de cultivo (16,2 ± 8,8 g) para estimar los requirimientos nutricionales de aminoácidos essenciales en la dieta, incluyendo cistina y tirosina, basada en el concepto de proteína ideal ((cada aminoácido essencial/lisina) x 100) y los resultados se correlacionaron con el perfil corporal de la tilapia del Nilo Oreochromis niloticus. El perfil dietético de aminoácidos essenciales explica el 5,46, 4,62, 1,16, 3,28, 5,63, 2,01, 2,59, 2,.84, 4,66, 3,39, 0.65 y 3,51% de la proteína, respectivamente para lisina, arginina, histidina, isoleucina, leucina, metionina, metionina+cistina, fenilalanina, fenilalanina+tirosina, treonina, triptófano y valina. Hubo una alta correlación lineal positiva (r = 0,971) entre el perfil corporal de aminoácidos de colirroja y el de tilapia del Nilo. Por lo tanto, el perfil corporal de los aminoácidos basado en el concepto de proteína ideal podría ser utilizado para estimar con precisión el requisito de aminoácidos essenciales de colirroja. Palabras clave: Astyanax fasciatus, aminoácidos, nutrición, proteína, concepto de proteína ideal, acuicultura. INTRODUCTION Protein is the most costly portion of aquaculture feeds. Estimating the amino acid requirements of fish is im__________________ Corresponding editor: Ronaldo Cavalli portant, because fish do not actually require dietary protein, but a rather well-balanced supply of dietary amino acids. The essential amino acid requirements have been established for only a few cultured fish spe- 2889 Latin American Journal of Aquatic Research cies (NRC, 2011). Individual amino acid requirements for fish have been determined by using time-consuming and costly dose-response feeding assays. As an alternative, the whole body composition of a species can be used to estimate simultaneously the requirements for all ten essential amino acids (Tacon, 1989). This technique has been currently used to estimate the essential amino acid requirements for fish (Portz & Cyrino, 2003; Gurure et al., 2007), because there is high correlation between the content of dietary amino acids required determined using dose-response experiments and that of amino acids in the whole body tissue (Wilson & Poe, 1985). Since the amino acid requirements of a growing animal are known to be reflected by its amino acid composition (Mitchell, 1950), the ideal protein concept that uses the relationships of each essential amino acid profile in relation to lysine has been developed as a basis to formulate diets for fish (Furuya et al., 2004a; Kaushik & Seiliez, 2010; NRC, 2011). The advantage of this concept is that it can be adapted to various situations, provided the relationships between amino acids do not change for a given growth stage (Portz & Cyrino, 2003). For fish, the quantitative lysine requirement might vary, but not the ideal amino acid profile expressed relative to lysine. Given the dietary requirement for lysine, the requirement for the remaining essential amino acids can be predicted based on the relative ratio of amino acids in the whole body. A. fasciatus (Cuvier, 1819) is an omnivorous freshwater fish; it is widely used as a game and food fish. Rapid growth, low dietary protein requirement, and mild white flesh attract consumers, rendering it an economically important fish. However, at present, the information on the dietary requirements for this fish species is not available. Thus, this study aimed to estimate the dietary essential amino acid requirement for colliroja by analyzing the whole body composition. Coleção Ictiológica at the Universidade Estadual de Maringá (NUP 11864), Maringá, Paraná, Brazil. The fish samples were obtained from two earth ponds of 300 m2 each. While collecting colliroja, 30 Nile tilapias (15 fish during each collection) were collected (621 ± 37 g) from a 100 m2 earth pond for whole body analysis of crude protein and amino acids. They were fed only naturally available feed and not artificial diets. Fish were caught using surface and bottom trawl nets (mesh size = 1 cm (colliroja) and 12 cm (Nile tilapia)), and placed in a 500 L indoor fiberglass tank aerated to maintain a dissolved oxygen of >5 and <6 mg·L-1. They were fasted for 24 h before the beginning of the experiment and euthanized by an overdose of benzocaine (3 g 10 L-1). The total length (0.1 cm) and body weight (0.01 g) of colliroja were measured. Fish samples were stored in a freezer at 80ºC for subsequent analysis. MATERIALS AND METHODS Analytical procedures Pooled samples of fish were ground in a meat grinder and analyzed in duplicate for body composition of moisture and protein, as per the standard methods (AOAC, 2003). Moisture content was determined by drying the samples in an oven (TE-391-1; Tecnal, Piracicaba, SP, Brazil) at 105°C until a constant weight was reached. Nitrogen content was determined using a micro-Kjeldahl apparatus, and crude protein was estimated by multiplying the nitrogen content by 6.25. Amino acid content was determined after acidic and basic digestion for chromatographic and ionic change analyses (high-performance liquid chromatography) performed in sealed glass tubes under nitrogen atmos- Fish and management The study was performed at an application unit of the Aquaculture Laboratory, Universidade Estadual de Ponta Grossa, Paraná, Brazil. Fish were obtained from a local fish farm (Piscicultura Águas Claras, Castro, Paraná, Brazil; 24o42’32”S, 50o02’37”W). In total, 120 cultivated mixed-sex fish (16.2 ± 8.8 g) were collected randomly in March (60 fish) and October (60 fish) of 2013, and fish collected during each month were divided in two groups (30 fish each) and considered as replicates. Specimens are deposited in the Núcleo de Pesquisa em Limnologia, Ictiologia e Aquicultura/ Calculation The whole body profile of essential amino acids, including cysteine and tyrosine, was expressed relative to the lysine content according to equation (1): EAAP = EAA/L × 100, where EAAP is the whole body essential amino acid profile, and L is the whole body lysine content. The dietary lysine requirement was estimated to be 5.46% of the protein; this represents the mean value of dietary lysine requirement of common carp (Cyprinus carpio), grass carp (Ctenopharyngodon idella), and Nile tilapia (Oreochromis niloticus) reported by the NRC (2011). The essential amino acid profile in the diets for colliroja was estimated according to equation (2): EAAD = 5.46 × (EAAP/100), where EAAP (% dietary protein) is the essential amino acid profile in the diet, 5.46 is the mean value of dietary lysine requirement (% dietary protein) of common carp, grass carp, and Nile tilapia (NRC, 2011), and EAAP is the whole body essential amino acid profile determined using equation (1). Amino acid requirements of Astyanax fasciatus phere at 110oC. Cysteine and methionine contents were determined by hydrolysis after oxidation with performic acid. After hydrolysis, the solutions were vacuumfiltered, diluted to 0.25 M with 0.02 N HCl for adjusting the pH to 8.5, and filtered through a Millipore membrane (0.45 mm). Tryptophan analysis was performed after alkaline hydroxylation of the samples with lithium hydroxide. Free amino acids were separated using an auto-analyzer (Hitachi L-8500A; Tokyo, Japan). Statistical analysis The results are presented as means ± standard deviation of duplicate samples. Data of whole body amino acid profile of Nile tilapia and colliroja were subjected to one-way analysis of variance (ANOVA), and differences between treatment means were determined using t-test. The correlation among the dietary essential amino acid profiles determined based on the ideal protein concept of Nile tilapia and colliroja was expressed using linear regression analysis, and each essential amino acid mean was compared using t-test (P < 0.05) by using the SPSS Statistical Package (Version 15.0; SP Inc., Chicago, IL). The dietary amino acid requirement was recommended as percentage of protein found in the whole body composition of colliroja. 8903 Table 1. Whole body composition of essential and nonessential amino acids of colliroja Astyanax fasciatus (dry matter basis). Values are mean ± standard deviation of two replicate analyses. Composition Crude protein Arginine Phenilalanine Phenilalanine + tyrosine Histidine Isoleucine Leucine Lysine Methionine Methionine + cysteine Threonine Tryptophan Valine Glutamic acid Aspartic acid Alanine Cysteine Glycine Serine Tyrosine % 42.44 ± 0.41 2.74 ± 0.05 1.64 ± 0.03 2.82 ± 0.04 0.76 ± 0.00 1.64 ± 0.03 2.89 ± 0.05 3.15 ± 0.06 1.04 ± 0.01 1.39 ± 0.01 1.66 ± 0.02 0.41 ± 0.00 1.92 ± 0.04 5.25 ± 0.07 3.64 ± 0.01 2.69 ± 0.01 0.34 ± 0.00 3.10 ± 0.01 1.68 ± 0.00 1.18 ± 0.01 essential amino acid profile recommended for colliroja is shown in Table 3. RESULTS The results of the quantitative analysis of whole body essential and non-essential amino acids of colliroja are shown in Table 1. Among the essential amino acids, the mean concentration of lysine in the whole body composition of colliroja was the highest, followed by those of leucine and arginine. The concentration of tryptophan was the lowest. The profiles of essential amino acids, including cysteine and tyrosine, of colliroja and Nile tilapia obtained on the basis of the ideal protein concept are shown in Table 2 and Figure 1. There were no differences between whole body concentrations of arginine, histidine, isoleucine, methionine, methionine+cysteine, phenylalanine, phenylalanine+tyrosine, and tryptophan of Nile tilapia and colliroja. However, Nile tilapia showed higher (P < 0.05) values of methionine, threonine, and valine than those in colliroja. Regression analysis showed high correlation (r = 0.9710) between whole body essential amino acid profiles of colliroja and Nile tilapia (Fig. 2); the regression could be described according to the following equation: y = 8.4964+6.4956x. The dietary DISCUSSION Among all essential amino acids, the proportion of lysine was high in colliroja; this is in agreement with the results obtained in carnivorous pikeperch, Sander lucioperca (Jarmolowicz & Zakęś, 2014), black bass, Micropterus salmoides (Portz & Cyrino, 2003), and omnivorous fish species (Abimorad & Castellani, 2011; Taşbozan et al., 2013). According to the ideal protein concept, amino acid profile is expressed relative to lysine content, because lysine is usually the first limiting amino acid and exclusively used for body protein synthesis. In addition, lysine is one of the most studied amino acids in fish nutrition, and adequate crystalline lysine supplementation is positively related to the growth and feed efficiency of fish (Wu, 2013). Despite the higher quantitative value of whole body lysine, the arginine to lysine ratio obtained for colliroja (0.87:1) approached 0.83:1 for Nile tilapia as revealed by a dose-response experiment (Santiago & Lovell, 1988) and 0.84:1 for channel catfish, Ictalurus punctatus (NRC, 2011). The lysine to arginine ratio might be evaluated in fish diets to avoid antagonisms, because impaired ratios of lysine or arginine can reduce fish growth and feed efficiency (Wu, 2013). Crystalline 4891 Latin American Journal of Aquatic Research Table 2. Whole body amino acid profile of colliroja A. fasciatus and Nile tilapia Oreochromis niloticus determined on the basis of the ideal protein concept. EEA/L: each essential amino acid (including cysteine and tyrosine) relative to lysine. Values are means ± standard deviation (n = 2), and values within the same row with different letters are significantly different (P < 0.05) by t-test. Amino acid Lysine Arginine Histidine Isoleucine Leucine Methionine Methionine + cysteine Phenylalanine Phenylalanine + tyrosine Threonine Tryptophan Valine Nile tilapia 100.00 ± 0.00 84.76 ± 10.82a 21.32 ± 1.43a 60.16 ± 2.57 a 103.39 ± 0.85a 36.95 ± 0.03a 47.51 ± 1.04a 52.09 ± 1.99a 85.56 ± 4.64a 62.15 ± 0.43a 11.85 ± 1.08a 64.34 ± 0.41a Figure 1. Whole body essential amino profile (including cysteine and tyrosine) of Nile tilapia Oreochromis niloticus and colliroja A. fasciatus determined on the basis of the ideal protein concept. Arg: arginine, His: histidine, Ile: Isoleucine, Leu: leucine, Met: methionine, Met+Cys: methionine+cysteine, Phe: phenylalanine, Phe+Tyr: phenylalanine+tyrosine, Thr: treonine, Trp: triptofano, and Val: valine. amino acid supplementation based on the ideal protein profile is useful for estimating the dietary requirement of all essential amino acids from the analysis of only one amino acid, lysine (NRC, 2011). EEA/L Colirroja 100.00 ± 0.00 87.13 ± 0.42a 24.07 ± 0.37a 52.08 ± 0.23a 92.01 ± 0.55b 33.12 ± 0.31b 44.01 ± 0.42a 52.08 ± 0.34a 89.51 ± 0.70a 52.60 ± 0.45b 12.88 ± 0.13a 61.06 ± 0.17b P-value 0.628 0.399 0.165 0.013 0.033 0.152 0.552 0.883 0.040 0.060 0.037 Cysteine and tyrosine are considered semi-essential because they are only biosynthesized from methionine and phenylalanine, respectively, and their dietary requirement should be presented as the sum of methionine+cysteine (sulfur amino acids) and phenylalanine+tyrosine (aromatic amino acids; Wu, 2013). However, methionine is the most limiting amino acid in soybean meal, one of the most frequently used plantprotein in fish diets, and minimum dietary methionine is included during feed formulation to avoid methionine deficiency (Furuya et al., 2004b). In contrast, phenylalanine is not considered a limiting amino acid in fish nutrition, and few studies have determined its dietary requirement. There are contradicting results on methionine and total sulfur amino acid concentrations determined in dose-response experiments and values estimated from whole body amino acid composition of fish. The dietary amino acid requirements of colliroja were compared to those of Nile tilapia obtained from dose-response experiments and whole body analysis, considering the similarity between colliroja and Nile tilapia in terms of food habits (omnivorous) and taxonomic classification (Characidae family). Moreover, both are freshwater fish, and the complete dietary requirement of all essential amino acids is known for Nile tilapia (NRC, 2011). Santiago & Lovell (1988) described the dietary sulfur amino acid requirement of 0.90% for fingerlings of Nile tilapia fed purified diet, which included 0.75% of methionine and 0.25% of cysteine. However, Furuya et al. (2004b) suggested the requirement of 1.13% sulfur amino acids, including 0.54% of methionine. The proportion of methionine was higher in relation to cysteine (0.83:0.17) in the purified diets used by Santiago Amino acid requirements of Astyanax fasciatus 892 5 Figure 2. Linear correlation between Nile tilapia Oreochromis niloticus and colliroja Astyanax fasciatus whole body amino acid profile determined on the basis of the ideal protein concept (EEA/L × 100), considering the essential amino acids (EAAs) to lysine (L) ratios. Arg: arginine, His: histidine, Ile: Isoleucine, Leu: leucine, Met: methionine, Met+Cys: methionine+cysteine, Phe: phenylalanine, Phe+Tyr: phenylalanine+tyrosine, Thr: treonine, Trp: triptophan, and Val: valine. Table 3. Dietary quantitative essential amino acid requirement (including cysteine and tyrosine) of colliroja Astyanax fasciatus considering the diets containing different levels of crude protein (as feed basis). Amino acid Lysine Arginine Histidine Isoleucine Leucine Methionine Methionine + cysteine Phenylalanine Phenylalanine + tyrosine Threonine Tryptophan Valine Dietary amino acid profile (% dietary protein) 5.46 4.62 1.16 3.28 5.63 2.01 2.59 2.84 4.66 3.39 0.65 3.51 & Lovell (1988), whereas Teixeira et al. (2008) revealed a methionine to cysteine ratio of 0.75:0.25 for Nile tilapia by analyzing the body composition. There is a discrepancy in these ratios because food used for the preparation of commercial diets for fish and other aquatic organisms possess higher proportions of cysteine relative to methionine, unlike that in purified casein, which is the main protein source used in fish nutrition dose-response studies. Adequate dietary methionine supplementation is necessary for the maximum growth and health of fish. Methionine plays a role in protein synthesis and is important for physiological functions. Further, it is essential for normal growth of fish and is a donor of methyl groups required for methylation reactions via S-adenosylmethionine (Bender, 2003). S-adenosylmethionine is synthesized from methionine, which is then catalyzed by adenosyl triphosphate cyclase, allowing methyl group donation to various substrates, including nucleic acids, proteins, phospholipids, and biogenic amines. The S-adenosyl methionine generates compounds such as carnitine (Wu, 2013), cysteine, and choline (Kasper et al., 2000), which are important compounds required for the metabolism of lipids and affect the growth performance and lipid deposition of Nile tilapia (Graciano et al., 2010). The complete quantitative essential amino acid requirements have been established for only a few fish species (NRC, 2011), and determining the amino acid requirements of the new aquacultural species colliroja is of economic importance. Dose-response experiments require large numbers of feeding trials to determine individual essential amino acid profiles. In addition, these trials are time-consuming and very costly. As a practical alternative, whole body essential amino acid profile has been extensively used to estimate simultaneously the requirements for all essential amino acids. This technique was used in the present study by considering that dietary amino acid profile is close to the pattern in the muscle tissues of fish (Mitchell, 1950; Fuller et al., 1989). However, the whole body amino acid composition varies across fish species (Bicudo et al., 2009). To date, Taşbozan et al. (2013) found large variations among whole body amino acid profiles of five different Tilapia species. Thus, estimating the dietary amino acid requirements for each fish species is 6893 Latin American Journal of Aquatic Research important for precisely formulating aquafeeds. However, the quantitative dietary requirement of fish is more precisely obtained by dose-response experiments compared to estimates from whole body amino acid profiles (NRC, 2011). Nonetheless, comparison of profiles obtained using the two methods in colliroja and Nile tilapia revealed that there is not much difference in the estimated values. In conclusion, the whole body composition of amino acids might be used to estimate the dietary requirements of essential amino acids, including cysteine and tyrosine, for new aquaculture fish species such as colliroja. tilápia-do-nilo alimentados com dietas suplementadas com metionina e colina. Pesq. Agropec. Bras., 45: 737743. Gurure, R., J. Atkinson & R.D. Moccia. 2007. Amino acid composition of Arctic charr, Salvelinus alpinus (L.) and the prediction of dietary requirements for essential amino acids. Aquacult. Nutr., 13: 266-272. Jarmolowics, S. & Z. Zakęś. 2014. Amino acid profile in juvenile pikeperch (Sander lucioperca (L.) impact of supplementing feed with yeast extract. Arch. Pol. Fish., 22: 135-143. ACKNOWLEDGMENTS Kasper, C.S., M.R. White & P.B. Brown. 2000. Choline is required by tilapia when methionine is not in excess. J. Nutr., 130: 238-242. We are grateful to Ajinomoto do Brasil Indústria e Comércio de Alimentos Ltda. - Animal Nutrition Division, for performing the amino acid analysis. Kaushik, S.M. & I. Seiliez. 2010. Protein and amino acid nutrition and metabolism in fish: current knowledge and future needs. Aquacult. Res., 41: 322-332. REFERENCES Abimorad, E.G. & D. Castellani. 2011. Exigências nutricionais de aminoácidos para o lambari-do-raboamarelo baseadas na composição da carcaça e do músculo. Bol. Inst. Pesca, 37: 31-38. Association of the Official Methods of Analysis (AOAC). 2003. Official Methods of Analysis, Association of Official Analytical Chemists, Washington, D.C., 1115 pp. Bender, D.A. 2003. 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Tacon, A.J. 1989. Nutrición y alimentación de peces y camarones cultivados. FAO, Brasília, 572 pp. Taşbozan, O., O. Özcan, C. Erbaş, E. Ündağ, A. Atici & A. Adakli. 2013. Determination of proximate and amino acid composition of five different Tilapia Species from the Cukurova Region (Turkey). J. Appl. Biol. Sci., 7: 17-22. Teixeira, E.A., D.V. Crepaldi, P.M.C. Faria, L.P. Ribeiro, D.C. de Melo & A.C.C. Euler. 2008. Composição corporal e exigências nutricionais de aminoácidos para alevinos de tilápia (Oreochromis sp.). Rev. Bras. Saúde Prod. Anim., 9: 239-246. Wilson, R. & E.W.E. Poe. 1985. Relationship of whole and egg essential amino acid patterns to amino acid Amino acid requirements of Astyanax fasciatus requirement patterns in channel catfish (Ictalurus punctatus). Comp. Biochem. Physiol. B, 80: 385-388. Wu, G. 2013. Amino acids: biochemistry and nutrition. CRC Press, Boca Raton, 481 pp. Received: 6 August 2014; Accepted: 17 August 2015 8947 Lat. Am. J. Aquat. Res., 43(5): 895-903, 2015Dimorphism on the marine catfish Genidens genidens DOI: 10.3856/vol43-issue5-fulltext-9 Research Article Biometric sexual and ontogenetic dimorphism on the marine catfish Genidens genidens (Siluriformes, Ariidae) in a tropical estuary Larissa G. Paiva1, Luana Prestrelo1,2, Kiani M. Sant’Anna1 & Marcelo Vianna1 Laboratório de Biologia e Tecnologia Pesqueira, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373 Bl. A, 21941-902 Rio de Janeiro, RJ, Brazil 2 Fundação Instituto de Pesca do Estado do Rio de Janeiro, Escritório Regional Norte Fluminense II Avenida Rui Barbosa 1725, salas 57/58, Alto dos Cajueiros, Macaé, RJ, Brazil 1 Corresponding author: Larissa G. Paiva ([email protected]) ABSTRACT. This paper aims to study the ontogenetic sexual dimorphism of Genidens genidens in Guanabara Bay, southeastern coast of Brazil. Altogether 378 specimens were anayzed (233 females and 145 males) with total length ranging from 13.3 to 43.5 cm. Specimens were measured for 12 body measurements, sex was identified and maturity stages were recorded and classified. Pearson’s linear correlation reveled a significant positive correlation between total length and all other body measures, except for base adipose fin, mouth depth and eye depth for immature females. Analyses nested PERMANOVA desing showed significant differences between maturity stages for each sex, between sexes considering or not maturity stages, indicating a variation in morphometric characteristics driven by sexual dimorphism. Differences among all maturity stages were also found, indicating an ontogenetic morphological difference. But immature individuals didn’t differ between sexes indicating that differentiation patterns starts with sexual development. The most important measures differing males and females were related to head characteristics, which appears to be key parameters to evaluate sexual differences. Due to male incubation of fertilized eggs and juvenile individuals <59 mm in their oral cavity, head measures are proposed to be sex dimorphism not related to reproduction, but with post reproductive fase due to ecological and biological needs. Keywords: Genidens genidens, catfish, Teleostei, morphometry, biometry, dimorphism, tropical estuary. Biometría sexual y dimorfismo ontogenético en el bagre marino Genidens genidens (Siluriformes, Ariidae), en un estuario tropical RESUMEN. Se analizó el dimorfismo sexual y ontogenético del bagre marino Genidens genidens en la Baía de Guanabara, costa sureste de Brasil. Se capturó un total de 378 ejemplares (233 hembras y 145 machos) con longitud total entre 13,3 y 43,5 cm. Se realizaron 12 medidas morfométricas, además de identificar el sexo y los estadios de madurez de los individuos. La correlación lineal de Pearson reveló correlación positiva significativa entre la longitud total y otras medidas corporales excepto la base de la aleta adiposa, altura de la boca y altura de los ojos en hembras inmaduras. Los análisis de PERMANOVA anidados mostraron diferencias significativas entre los estados de madurez de cada sexo, entre los sexos, considerando o no, los estados de madurez, lo que indica una variación en las características morfométricas reguladas por el dimorfismo sexual. También se encontraron diferencias entre los estadios de madurez, lo que indica una diferencia ontogenética para el sexo y estadios de madurez. Los individuos inmaduros no difirieron entre los sexos, indicando que los patrones de diferenciación se inician sólo con el desarrollo sexual. Las medidas más importantes que difieren entre machos y hembras se relacionaron con las características de la cabeza que, al parecer, serían los principales parámetros para evaluar las diferencias sexuales. Debido a que los machos realizan la incubación en su cavidade oral de los huevos fertilizados y de individuos juveniles <59 mm, se sugiere que las medidas de la cabeza corresponden a un dimorfismo sexual no relacionado con la reproducción, pero vinculado a una fase post-reproductiva debido a sus necesidades ecológicas y biológicas. Palabras clave: Genidens genidens, bagre, Teleostei, morfometría, biometría, dimorfismo, estuario tropical. __________________ Corresponding editor: Guido Plaza 895 896 Latin American Journal of Aquatic Research INTRODUCTION It is well known that morphology is directly related to species life history and habitat use. Thus fish morphometric analysis represents an important tool to determine their systematic, growth variation, population parameters and environmental relationships (Kováč et al., 1999; Pathak et al., 2013; Sampaio et al., 2013; Souza et al., 2014). Morphometry cover several study fields such as: ecomorphology, relating species morphology with environment characteristics and evaluating the role of environmental preasures on shaping species diet, feeding behavior, ecological strategies, niche partitioning, habitat use and trophic structure (Peres-Neto, 1999; Haas, 2010; Manimegalai et al., 2010; Palmeira & Monteiro-Neto, 2010; Souza et al., 2014) population ecology and metapopulations studies, investigating differences in body shape among populations spatially isolated (Gunawickrama, 2007; Mwanja, 2011; Santos & Quilang, 2012; Sampaio et al., 2013; Souza et al., 2014) and taxonomy, to differ and describe species and taxonomic groups based on internal and external features, which can result in misidentification if the individual is of diferent life stage than the ones used for classification (Marceniuk, 2005a, 2005b). However, intraspecific characteristics are often forgotten in studies investigating species morphological diversity, mainly in taxonomic studies. When this occurs, males and females of the same species may be identified as different species, therefore information about morphological sexual variation is important to avoid species misleading identification (Rapp Py-Daniel & Cox-Fernandes, 2005; Marceniuk, 2007). Sexual dimorphism can be an important evolutionay adaptation mechanism, conditioning sexual selection and diminishing intraspecific competition by encreasing nich partioning (Hedrick & Temeles, 1989; Herler et al., 2010), being an important study fill whithin morphometric research. An organism must function properly in all life stages and function and form are strictly related (Galis et al., 1994). Ontogenetic changes can determinate the success of an individual due to the importance of morphological features, environment adaptation and reproductive selection. Thus clarify how morphological changes develop throughout individuals growth is important to establish the relationship between morphology and behaviour, elucidating possible ontogenetic nich shifts and the evolutionary plasticity of an organism (Galis et al., 1994). Marine catfish of the genus Genidens (Siluriformes, Ariidae) are endemic of South Atlantic coasts and are commercially important estuarine fishes in Brazil (Mendoza-Carranza & Vieira, 2009; Silva-Junior et al., 2013). Due to Ariidae benthic habits and broad diet, they have good potential for biomonitoring studies (Azevedo et al., 2012). Furthermore studies with Genidens genidens (Curvier, 1829) in Guanabara Bay and Santos-São Vicente estuary suggested that they should be used as estuarine sentinels, due to their tolerance to eutrophication and others anthropogenic changes (Azevedo et al., 2012; Silva-Junior et al., 2013). In Guanabara Bay, a Brazilian tropical estuary, G. genidens is one of the most abundant species, occupying shallow waters with low salinity and low water transparency (Rodrigues et al., 2007; SilvaJunior et al., 2013). Guanabara Bay has great economic and social importance due to fishing and navigation activities, industrial surrounding areas and ecological relevance due its importance for many marine and freshwater lifecycle (Vasconcelos et al., 2010). Despite their ecological importance G. genidens’s morphological sexual and ontogenetic variations are little known. This paper is the first study aiming to evaluate G. genidens’s morphological changes between sexes and through ontogenetic development. It will provide more detailed biometric information on the species which could assist further studies on its biology and ecology. MATERIALS AND METHODS Guanabara Bay is located in Rio de Janeiro State, southeastern Brazil (22°40’S, 43°02’W) (Fig. 1). It has an area of 384 km², 7.6 m of mean depth and has an average water residence time of 20 ± 5 days. It is an estuarine environment with minimum salinity of 25 and maximum of 34.5, low hydrodynamics, small grain size bottom and great influence of freshwater runoff and domestic sewage resolting in a major eutrophicated system (Kjerfve et al., 1997; Quaresma et al., 2000). Specimens of G. genidens (voucher MNRJ 42040) were collected, twice a month, from August 2010 to September 2011. Samples were collected covering the three most important local fisheries (gill net, bottom trawl and stationary pound net) and all Guanabara Bay habitat zones. All specimens were cooled on ice and then measured for 11 body measures (by convention, always on the left side) using a ichtyometer and a electronic caliper rul with precision of 0.01 mm, without being fixed, according to metric measures proposed by Marceniuk (2005a) and Souza & Barrella (2009) (Fig. 2) (Table 1). Measures were standardized as a percentage of total length (TL), excluding total length’s effect on body measures. The determination of sex and sexual maturity stages were made by gonads macroscopic observation through an adaptation of Dimorphism on the marine catfish Genidens genidens 897 RESULTS Figure 1. Study location highlighting Guanabara Bay in Rio de Janeiro state, southeastern coast, Brazil. A total of 378 specimens were captured, 233 females (immature (A) = 9, in maturation process (B) = 68, mature (C+D) = 156) and 145 males (immature (A) = 27, in maturation process (B) = 53, mature (C+D) = 65). Total length ranged from 13.3 to 43.5 cm (Fig. 3). Morphometric features and Pearson’s linear correlations are presented in Table 2. Body measures were significant correlated with total length (TL), except for base adipose fin (AF), mouth depth (MD) and eye depth (ED) of immature females (Table 2). Morphometric measures showed significant differences for maturity stages within sex, sex within maturity stages and between sexes, but not for maturity stages alone (Table 3a), indicating a possible alteration in morphometric characteristics driven by sexual dimorphism along with maturation process. The post-hoc test showed a significant difference between sexes for all maturity stages except A, indicating that imamture individuals did not have morphological differences and the differentiation only starts at the beginning of sexual development (Table 3b). SIMPER analysis indicated maximum body depth (BD), upper caudal fin lobe length (CL), head length (HL), barbeus length (BL), interorbital distance (ID) and mouth depth (MD) as the six most important metric measurements descrimitating females from males and the group A from B and C+D. DISCUSSION Vazzoler (1996): A = immature, B = in maturation process, C+D = mature. The degree of association between G. genidens size and body proportions, within sex and maturity stages were tested with Pearson’s linear correlation analyses using Statistica 8 software, with the significance level of 0.05. A multivariate nested PERMANOVA design was used to evaluate differences in maturity stages within each sex [maturity (sex)] (ontogenetic differences) and between sexes within maturity stages [sex (maturity)] (sexual dimorphism). A pair-wise post-hoc test was performed to further investigate differences between groups. This test uses an ANOVA experimental design on the basis of any distance measure, using Monte Carlo permutation method (Anderson, 2005) and provides which factor was most important for data differences. A pair-wise post-hoc test was performed to analyze differences among male and female maturity stages. SIMPER analysis was performed to evaluate witch metric measurements were most important for determining group dissimilarity. These analyses were performed using Primer 6 + PERMANOVA software (Clarke & Gorley, 2006). The present study evaluated morphological onthogenetic changes in Genidens genidens and found a well defined sexual dimophism reveled through changes in head measures. Those differences are related to the maturity process responsible for differing male from female individuls due to their reproductive role. Sexual dimorphism may be an evolutionary adaptative mechanism favouring sexual selection, acting on males when females for choosing partners for mating and in mate competition, enhancing selection towards certain male traits (Hedrick & Temeles, 1989). When compered with other vertebrates, teleosts have a wide range of sexual dimorphism described, including color, size, shape and feeding mechanisms (Kitano et al., 2007; Herler et al., 2010; Mcgee & Wainwright, 2013). For G. genidens sexual dimorphism has been observed in pelvic fins, that are higher in females compared to males (Barbieri et al., 1992), but it had never been evaluated to ontogenetic variations along with sexual changes until this study. Ontogenetic differences have been described by most studies based on morphology but they are often 898 Latin American Journal of Aquatic Research Figure 2. Body measures used to characterize Genidens genidens’s biometrics. TL: total length, AF: base adipose fin, CF: base caudal fin, BL: barbeus length, HL: head length, CL: upper caudal fin lobe length, ID: interorbital distance, BD: maximum body depth, ED: eye depth, BW: mouth width, MD: mouth depth. This image is a modification of Figueiredo & Menezes (1978). Table 1. Description of body measures used to characterize Genidens genidens’s biometrics. Measurements Code Description Total length Base adipose fin Base caudal fin Barbeus length Head length Upper caudal fin lobe length Interorbital distance Maximum body depth Eye depth Maximum body width Mouth width Mouth depth TL AF CF BL HL CL ID BD ED BW MW MD Greater distance between the tip of the snout and caudal fin. Distance between the beginning and end of adipose fin. Height of the top of the caudal fin. Distance between the base and the end of the longest barbel. Distance from the tip of the snout to the end of the operculum. Distance between the base of the caudal fin and the tip of the upper lobe of the caudal fin. Distance between the eyes taken from the upper portion. The longest distance between the belly and back perpendicular to the body axis. Taken away the eyes of the height of the iris to the womb. Largest body width. Internal distance from the mouth when fully open. Greater distance between the measured lips with mouth open, stretch the muscles without. related to feeding habits and habitat use (Zimmerman et al., 2009; Lima et al., 2012) and not to diffenreces between sex. We observed differences between male and female in head measures (BD, CL, HL, BL, ID, MD), which we suggest to be the key parameters to evaluate sexual dimorphism in this species. Head measures where bigger in male than female probably due to their different roles on the reproductive process, since marine catfish have parental care where male incubates fertilized eggs and larvae in their mouth (Velasco et al., 2006; Silva-Junior et al., 2013). We know that G. genidens, beyond fertilized eggs, the incubators males may present in their oropharyngeal cavity larvae up to 59 mm (Chaves, 1994). Changes in head measures also have been observed in fish species, related with oral incubation behavior. Herler et al. (2010), Figure 3. Frequency distribution of total length, of Genidens genidens, for female and male, in Guanabara Bay, Rio de Janeiro, Brazil. Dimorphism on the marine catfish Genidens genidens 899 Table 2. Morphometric characteristics, of Genidens genidens, and Pearson’s linear correlation (r), for the associations between total lenght and body proportions, within sex and maturity stages. Range: minimum and maximum values; 𝑥̅ = mean values (± standard deviation). *P < 0.05. **P < 0.001. Parameters Sex Female Total length (TL) Male Female Base adipose Fin (AF) Male Female Base caudal Fin (CF) Male Female Barbeus length (BL) Male Female Head length (HL) Male Female Upper caudal fin lobe length (CL) Male Female Interorbital distance (ID) Male Female Maximum body depth (BD) Male Maturity stage A B C+D A B C+D A B C+D A B C+D A B C+D A B C+D A B C+D A B C+D A B C+D A B C+D A B C+D A B C+D A B C+D A B C+D A B C+D A B C+D Range (cm) 14.1 - 18.9 14.1 - 41.4 16.4 - 43.5 13.3 - 24.9 16.1 - 33.4 17.5 - 38.6 0.8 - 1.1 0.9 - 3.2 0.6 - 3.4 0.7 - 1.7 1.0 - 4.8 0.6 - 2.9 1.3 - 1.8 0.9 - 4.5 0.7 - 6.1 1.0 - 2.5 1.4 - 4.5 1.8 - 6.2 2.5 - 3.8 2.8 - 7.7 3.2 - 7.9 1.6 - 4.6 3.2 - 6.3 3.0 - 7.9 2.8 - 3.8 2.6 - 8.3 2.3 - 9.4 2.6 - 5.8 2.5 - 7.5 2.7 - 9.1 3.1 - 3.8 2.8 - 8.3 2.2 - 8.3 2.6 - 4.5 1.6 - 6.5 3.3 - 7.5 0.9 - 1.6 0.9 - 4.1 1.1 - 4.4 0.8 - 2.1 1.1 - 3.5 1.2 - 4.0 2.3 - 3.2 1.8 - 7.1 1.4 - 7.0 1.5 - 3.8 2.4 -6.3 2.4 - 6.3 𝑥̅ (± SD) 15.7 (± 1.5) 26.3 (± 6.9) 26.4 (± 4.1) 18.4 (± 2.9) 23.0 (± 4.1) 25.9 (± 5.1) 1.0 (± 0.1) 1.8 (± 0.6) 1.8 (± 0.4) 1.3 (± 0.3) 1.7 (± 0.5) 1.8 (± 0.5) 1.5 (± 0.2) 2.6 (± 0.8) 2.6 (± 0.6) 1.8 (± 0.3) 2.3 (± 0.6) 2.6 (± 0.7) 3.1 (± 0.4) 4.8 (±1.2) 4.8 (± 0.8) 3.5 (± 0.6) 4.4 (± 0.8) 4.7 (± 1.0) 3.1 (± 0.3) 5.3 (± 1.5) 5.4 (± 1.0 ) 3.6 (± 0.8) 4.9 (± 1.1) 5.7 (± 1.4) 3.3 (± 0.2) 5.2 (± 1.4) 5.3 (± 1.0) 3.6 (± 0.5) 4.4 (± 1.1) 5.1 (± 1.1) 1.2 (± 0.2) 2.2 (± 0.8) 2.2 (± 0.5) 1.4 (± 0.4) 2.0 (± 0.5) 2.4 (± 0.7) 2.5 (± 0.3) 4.1 (± 1.2) 4.1 (± 0.7) 2.7 (± 0.6) 3.5 (± 0.8) 4.0 (± 0.9) r - 0.5 0.9** 0.8** 0.9** 0.7** 0.8** 0.9** 0.9** 0.9** 0.8** 0.6** 0.8** 0.7* 0.9** 0.9** 0.9** 0.9** 0.9** 0.9** 1.0** 0.9** 0.8** 0.7** 0.9** 0.9* 0.9** 0.8** 0.9** 0.8** 0.9** 0.9* 1.0** 0.9** 0.9** 0.9** 0.9** 0.9** 0.9* 0.8** 0.9** 0.9** 0.9** 900 Latin American Journal of Aquatic Research Continuation Parameters Sex Female Mouth depth (MD) Male Female Eye depth (ED) Male Female Maximum body width (BW) Male Female Mouth width (MW) Male investigated the sexual dimorphism in populations of the cichlid genus Tropheus, oral incubators fishes, in Lake Tanganyika, in Africa, and found significant differences in mean shape between sexes among the seven populations analyzed related to oral landmarks with larger head length and ventral area (buccal region) in females (the oral breeders). Barnett & Bellwood (2005) investigated the sexual dimorphism in seven fish species with incubation behaviour of eggs and larvae in the oral cavity, in Lizard Island, and observed that males had bigger oral volumes than females in five of them. For some fishes, clear morphometric differences between sexes appear only in certain gonadal stages in specific body measurements, as observed in this study. Manimegalai et al. (2010) studied the ciclhid Etroplus maculates in India and observed significant correlation between body length growth and morphometric measure and suggested that body measures increases as a function of total growth. Kitano et al. (2007) studied Gasterosteus aculeatus (Gasterosteidae) and also observed sexual dimorphism only after the fish became reproductively mature. Lima et al. (2012) studied the development and allometric growth patterns of the Ariidae catfishes Cathorops spixii and C. agassizii and observed that after hatching, mouth-breeded free embryos of both species grow isometric in all body Maturity stage A B C+D A B C+D A B C+D A B C+D A B C+D A B C+D A B C+D A B C+D Range (cm) 0.8 - 1.3 0.8 - 3.1 1.0 - 3.5 0.6 - 1.9 0.9 - 3.0 1.0 - 2.9 0.6 - 1.3 0.5 - 2.0 0.5 - 2.3 0.3 - 1.2 0.5 - 2.2 0.6 - 1.9 1.9 - 3.0 2.2 - 6.4 2.0 - 6.6 2.0 - 4.1 2.5 - 5.6 2.8 - 6.6 0.9 - 1.3 0.9 - 4.1 1.2 - 4.1 0.8 - 2.1 1.0 - 2.9 1.4 - 4.0 𝑥̅ (± SD) 1.0 (± 0.2) 1.8 (± 0.5) 1.7 (± 0.4) 1.3 (± 0.3) 1.6 (± 0.4) 1.8 (± 0.5) 0.8 (± 0.4) 1.1 (± 0.4) 1.0 (± 0.3) 0.7 (± 0.2) 0.9 (± 0.3) 1.0 (± 0.3) 2.4 (± 0.3) 4.1 (± 1.1) 4.2 (± 0.7) 2.9 (± 0.5) 3.6 (± 0.7) 4.2 (± 0.9) 1.1 (± 0.1) 2.1 (± 0.8) 2.1 (± 0.5) 1.3 (± 0.3) 1.8 (± 0.4) 2.2 (± 0.6) r 0.5 0.9** 0.7** 0.5* 0.5** 0.8** 0.2 0.8** 0.8** 0.6* 0.7** 0.8** 0.9** 0.9** 0.9** 0.9** 0.7** 0.9** 0.8* 0.9** 0.9** 0.9** 0.9** 0.9** regions, suggesting that they already bear most of characteristics of adult fish. They suggested that the quick growth of morphometric features related to sensorial organs before hatching, reflect the developmental priorities during the earliest stages when important sensorial organs are being developed for juvenile survival strategies. Our study suggests that the priorities in development of specific body features of G. genidens returns when it reaches maturity and the proportional development of body measures and individual growth can occur differently between male and female especially due different reproduction roles between sexes. Thus when sexual maturity starts males concentrate their growth in head features increasing breeding capacity and reproduction success while female maintain their normal growth. Our study showed the importance of considering ontogenetic changes related to sex in G. genidens since changes in morphological measures observed around the mouth region is a feature related to male’s mouth breeding behavior during reproductive period. Thus the observations made in the present study related to changes in morphometric characteristics in male G. genidens are important to assist future studies about species biology and morphology. Moreover our study also highlight that the same ontogenetic changes may occur with other Ariidae species due to the family’s Dimorphism on the marine catfish Genidens genidens Table 3. a) Nested PERMANOVA results, df: degrees of freedom, F: test value, P (MC): Monte Carlo asymptotic P-values. Significance level 95% (P < 0.05), b) Post-hoc pair-wise test between male and female for each maturity stage. a) Source of variation Sex Maturity Maturity (sex) Sex (maturity) b) Maturity Stages A B C df 1 3 6 4 F 2.94 0.98 3.10 3.96 P (MC) 0.00 0.51 0.00 0.00 t 0.97 2.06 3.70 P (MC) 0.46 0.00 0.00 similar reproductive behavior (Figueiredo & Menezes, 1978), thus further studies should be develop aiming to elucidate this pattern which can be essential for a better understanding of the biology, behaviour and life history of those species as well as to determine differences between populations (Kitano et al., 2007). Marceniuk (2005a, 2005b) discribed Ariidae species of Brazilian coast based on morphological characteristics but didn’t observed sexual variations to differenciate species groups. Those studies considered morphological characteristics, neurocranium patterns and vomero-palatine tooth patches. Despite the sex and ontogenetic variation observed in our study for G. genidens, Marceniuk’s works are important identification guides for Ariidae family since they are based on other body characteristics besides morphometric measures. Morphometric estimates differ in degree of precision due to variation in fixation and storage methods and sometimes body structures are injured, making accurate measurements difficult. Nevertheless, due to the importance of these structures for reproduction, we assume that this bias is minimal. The parameters obtained here are realistic and our analysis showed an important role of head measurements in sex dependent ontogenetic differentiation driven by species behavior. We suggest that these measurements are secondary sexual characters not directly related to reproduction. 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Krueger, M.J. Van der Zanden & R.L. Eshenroder. 2009. Ontogenetic niche shifts and resource partitioning of lake trout morphotypes. Can. J. Fish Aquat. Sci., 66: 1007-1018. Lat. Am. J. Aquat. Res., 43(5): 904-911, 2015 DOI: 10.3856/vol43-issue5-fulltext-10 Extracto de pionilla en el cultivo de L. vannamei 9041 Research Article Efecto de la adición de un extracto acuoso de pionilla Lasianthaea podocephala en el cultivo del camarón blanco del Pacífico Litopenaeus vannamei en condiciones de laboratorio Emmanuel Villanueva-Gutiérrez1, Luis Rafael Martínez-Córdova1 Marcel Martínez-Porchas2 & Miguel Antonio Arvayo2 1 DICTUS, Universidad de Sonora, Blvd. Luis Donaldo Colosio entre Reforma y Sahuaripa, Hermosillo, Sonora 2 Centro de Investigación en Alimentación y Desarrollo Km 1,5 Carretera a La Victoria, Hermosillo, Sonora, México Corresponding author: Luis Rafael Martínez-Córdova ([email protected]) RESUMEN. Se evaluó el efecto de dos concentraciones de un extracto acuoso de la raíz de pionilla (Lasianthaea podocephala Gray), sobre las variables de la calidad del agua, condición fisiológica y parámetros de producción del camarón blanco del Pacífico, Litopenaeus vannamei (Boone), cultivado en condiciones intensivas de laboratorio. Dos tratamientos y un control fueron evaluados por triplicado: T1 (1 mL de extracto por acuario), T2 (3 mL) y C (control, 0 mL). No se observó un efecto negativo de los tratamientos sobre los parámetros de la calidad del agua, los cuales estuvieron dentro de rangos aceptables, sin presentar diferencias significativas entre tratamientos (P < 0,05). Algunos de los parámetros de producción tales como la supervivencia, biomasa final y FCA fueron mejores en los tratamientos en que se utilizó el extracto bajo las condiciones experimentales empleadas. La concentración de metabolitos hemolinfáticos, sugiere que los organismos cultivados en los acuarios con extracto tuvieron mejores condiciones, considerando los niveles mayores de proteína y colesterol en su músculo en relación con el control; además los resultados de expresión de genes indican que el extracto podría tener algún efecto inmunoestimulante sobre los camarones. No obstante, se recomienda efectuar estudios adicionales para evaluar y determinar a nivel molecular los ingredientes activos de los tubérculos de raíz de pionilla, para obtener mayor información sobre el uso potencial de este vegetal en la acuacultura. Palabras clave: Lasianthaea podocephala, Litopenaeus vannamei, producción, metabolitos hemolinfáticos, calidad del agua, respuesta inmune. Effect of the addition of an aqueous extract of the San Pedro Daisy Lasianthaea podocephala, in the culture of the Pacific white shrimp, Litopenaeus vannamei, under laboratory conditions ABSTRACT The effect of two concentrations of an aqueous extract of the San Pedro Daisy, (Lasianthaea podocephala Gray) roots was evaluated on the water quality, physiological condition and production parameters of the white Pacific shrimp, Litopenaeus vannamei (Boone), farmed under intensive laboratory conditions. Two treatments and a control were considered: T1 (1 mL of extract per aquarium), T2 (3 mL of the extract per aquarium) and C (control, 0 mL of the extract). No negative effects of the treatments on water quality parameters were observed, which ranged into acceptable limits and without significant differences (P < 0,05). Some of the production parameters such as final biomass and FCA were slightly better in the treatments using the extract. The concentration of haemolymph metabolites indicate that shrimp from treatments with the extract were under better conditions, suggested by the levels of protein and cholesterol in the muscle; moreover, the gene expression results suggest that the extract could have an immunostimulatory effect on shrimp. However, additional studies are required to evaluate the active ingredients of the root extract at the molecular level in order to have more information for the potential use of the plant. Keywords: Lasianthaea podocephala, Litopenaeus vannamei; shrimp production, haemolymph metabolites, water quality, immune response. __________________ Corresponding editor: Erich Rudolph 905 2 Latin American Journal of Aquatic Research INTRODUCCIÓN En acuacultura es fundamental evaluar los requerimientos tanto ambientales como nutrimentales de cada especie, a fin de mantenerlos, en la medida de lo posible, dentro de los rangos óptimos para lograr una adecuada respuesta productiva y un buen estado sanitario. Un manejo adecuado de todos estos parámetros influirá en una menor contaminación a los cuerpos de agua ocasionada por las descargas de efluentes de los sistemas de cultivo (Sánchez et al., 2001; Martínez-Córdova, 2009; Martínez-Porchas & Martínez-Córdova, 2012). El manejo inadecuado de las prácticas acuaculturales tiene graves repercusiones en la actividad camaronícola. Entre ellos se destaca el manejo relacionado con el alimento y prácticas de alimentación, que representan alrededor del 50% de los costos operativos de la camaronicultura. El desperdicio de alimento no consumido se ha vuelto un problema serio a nivel mundial, ya que además del grave impacto ambiental, causa pérdidas económicas a las empresas camaronícolas. La adición de atrayentes, quimio-atractantes y aperitivos se considera crucial para garantizar la localización e ingesta de alimento en granjas comerciales, donde las condiciones a menudo resultan adversas para la fácil localización y posterior ingestión del alimento en los estanques (Lee & Meyers, 1997). Costero & Meyers (1993) destacan la importancia de los atrayentes químicos alimenticios en la formulación de dietas comerciales. Estas sustancias son ampliamente reconocidas como medio para incrementar la respuesta de las diferentes especies a un cierto alimento en términos de su atractabilidad y palatabilidad. Sin embargo, la mayoría de estos productos no han sido suficientemente probados y algunos tienen un precio extremadamente alto para su uso en los alimentos. Por lo anterior, es necesario buscar alternativas de productos naturales que puedan optimizar de alguna manera las condiciones de cultivo, ya sea como aperitivos para mejorar el consumo, o bien para mejorar alguna condición fisiológica, nutricional o de estrés en los organismos cultivados. Actualmente, la herbolaria medicinal es una práctica relativamente novedosa en la acuacultura y solo a partir de los 90’ comenzaron a desarrollarse investigaciones en esta disciplina. Sin embargo, las investigaciones en este campo y su empleo por los acuicultores son aún insuficientes a pesar de la probada efectividad e inocuidad de algunos de estos productos (Citarasu, 2010). Algunas hierbas medicinales utilizadas en la acuicultura promueven la capacidad de crecimiento, mejoran el sistema inmune y actúan como estimuladores del apetito; otras, tienen la capacidad de inducir la maduración, amortiguar el estrés y actuar como agentes antimicrobianos. Dichas características son de gran utilidad en el cultivo de camarones y peces, además de que tales productos no provocan daños graves al medio ambiente. Algunos estudios relacionados con el uso de plantas medicinales como estimuladores del apetito, incluyen los de Citarasu (2010), quien encontró que algunos extractos como el de pimienta, jengibre, canela, entre otros, son capaces de mejorar el rendimiento de los animales por la acción estimulante de las secreciones intestinales o por tener un efecto bactericida directo sobre la microflora intestinal. Martínez-Córdova et al. (2008), al evaluar el efecto de un extracto de Yucca schidigera (Roezl) en el alimento del camarón blanco Litopenaeus vannamei (Boone), encontraron una disminución significativa de los niveles de nitrógeno amoniacal en la columna de agua y una mejora en la respuesta productiva, a niveles de inclusión de 2 y 3 ppmil. Lasianthaea podocephala Gray, también conocida como pionilla de la montaña, es una pequeña hierba perenne distribuida en las laderas montañosas de la sierra de Sonora, México. El extracto acuoso de su raíz se utiliza en comunidades rurales como aperitivo y antiparasitario para las personas (Martin et al., 1998). Recientemente, se realizó un estudio en condiciones de laboratorio (Martínez-Porchas et al., 2013), donde se incluyeron en la dieta del camarón blanco, dos concentraciones diferentes de un extracto de la raíz y se encontró que no tiene efectos negativos sobre la calidad del agua, pero tiene efecto positivo en la supervivencia y ganancia de biomasa, con solamente 1% de inclusión en la dieta. De acuerdo a lo anterior, la presente investigación tiene como objetivo evaluar el efecto de la incorporación de un extracto acuoso de la raíz de L. podocephala directamente en la columna de agua, sobre el consumo de alimento, respuesta productiva y estado fisiológico del camarón blanco en condiciones de laboratorio. MATERIALES Y MÉTODOS El estudio fue realizado durante ocho semanas en las instalaciones del Laboratorio Húmedo de Acuacultura del Departamento de Investigaciones Científicas y Tecnológicas de la Universidad de Sonora, México (DICTUS). Nueve acuarios rectangulares de plástico con 40 L de capacidad fueron utilizados como unidades experimentales; el aporte de oxígeno disuelto (OD) en el agua fue suministrado por piedras difusoras conectadas a una red de distribución de aire unida a un 9063 Extracto de pionilla en el cultivo de L. vannamei soplador de 1/4 HP. Se utilizó agua de mar filtrada y esterilizada por medio de filtros de arena, un biofiltro y una lámpara de UV. Un total de 225 postlarvas de camarón blanco (0.06 ± 0.005 g de peso promedio) obtenidas del laboratorio “Maricultura del Pacífico S.A. de C.V.”, en Bahía de Kino, Sonora, se utilizaron en el experimento. Los camarones se distribuyeron en acuarios con una densidad de 125 m-2 (25 organismos por acuario). Una dieta comercial (Aquaprofile 35 de Purina®, México) se suministró dos veces al día en pequeñas charolas (12x12 cm), ajustando la ración de acuerdo al consumo aparente, siguiendo las recomendaciones de Salame (1993). Los tubérculos de la raíz de L. podocephala se recolectaron en campos ubicados en el Municipio de Sahuaripa, Sonora, México. Para la preparación del extracto, las raíces se lavaron previamente con agua estéril y posteriormente se secaron al horno a 60°C durante 8 h. Después del secado los tubérculos fueron triturados a pequeños trozos. La obtención del extracto acuoso se hizo mediante una infusión de 50 g de polvo de tubérculo en 1 L de agua destilada cocida durante 2 h en una plancha de calentamiento y agitación magnética. Posteriormente, se separó el extracto del residuo vegetal por filtración y se guardó en una botella de vidrio ámbar en refrigeración para su posterior utilización. Los tratamientos consistieron en el uso de dos concentraciones de extracto añadidos a la columna de agua a 1 y 3 mL L-1 y un tratamiento control sin la inclusión del extracto. Tanto los tratamientos como el control fueron evaluados por triplicado mediante un diseño experimental simple en un arreglo al azar. Las concentraciones se seleccionaron en base a experiencias preliminares y estudios realizados con otros extractos. Se efectuaron recambios semanales del 20% de agua, retirando mediante sifoneo manual los restos de fecas, alimento no consumido, organismos muertos y exoesqueletos producto de la ecdisis. Se determinaron los parámetros de la calidad del agua como temperatura, salinidad, oxígeno disuelto y pH, utilizando una sonda multiparamétrica (YSI 6600®). Las concentraciones de ortosfatos (PO4), nitritos (NO2), nitratos (NO3) y nitrógeno amoniacal total (NAT) se midieron semanalmente por espectrofotometría, utilizando un equipo programable HACH DR 2000. Al final del experimento se contaron y pesaron individualmente los organismos de cada tratamiento en una balanza digital (Sartorius® con una precisión de 0,1 g). Se evaluó el desempeño de los organismos en términos de peso final (PF), tasa de crecimiento específica (TCE), supervivencia (SF) y factor de conversión alimenticia (FCA), de acuerdo a la siguiente fórmula: Consumo de alimento total FCA = [ Biomasa ganada ] Para evaluar el estado de salud y detectar cambios fisiológicos del camarón, se tomó una muestra de 100 mg de tejido muscular del abdomen de 10 organismos de cada tratamiento. Los camarones de todos los tratamientos se dejaron de alimentar 24 h antes de ser muestreados y posteriormente, se extrajeron 10 camarones por acuario, los cuales se sacrificaron de inmediato. Cada muestra de tejido muscular se homogenizó (FastPrep 5G, MP Biomedicals EUA) y centrifugó (Legend XTR, Thermo, EUA) a 5000 g durante 30 min a 2°C. Posteriormente, se tomaron 10 µL de la muestra liquida sin residuo de tejido. Las mediciones de glucosa, lactato, colesterol y proteína se realizaron con kits comerciales de Randox (Laboratorios Randox, Oceanside, CA, EE.UU), utilizando un espectrofotómetro con lector de microplacas (BIORAD Model 680). Adicionalmente, se tomó una muestra de hepatopáncreas para medir la expresión de dos genes relacionados con el sistema inmune como proteína unidora de lipopolisacáridos y β-glucanos (LGBP) y profenoloxidasa (proPO). Se extrajo ARN del tejido por medio del kit comercial Master Pure RNA Purification Kit (Epicentre, EUA), la síntesis del ADN complementario se realizó utilizando el kit Quantitect Reverse Transcriptase Kit (QIAGEN, USA), seleccionando aquellas muestras con valores de absorbancia cercanos a 2 (260/280; NanoDrop, Thermo, EUA). Se utilizó 1 ug de ARN para medir la expresión relativa. La expresión de ambos genes se realizó mediante un termociclador Step One (Applied Biosystems, USA) utilizando un fluoróforo (iTaq™ universal SYBR® Green, BIORAD, EUA) e iniciadores específicos para cada gen (Tabla 2); el gen constitutivo L8 se consideró como control endógeno. Se efectuaron reacciones de 20 uL y se establecieron las siguientes condiciones térmicas: 1 ciclo de 5 min a 95°C, 40 ciclos de 30 seg a 95°C y 60 seg a 60°C, y un paso final de extensión a 60°C. La expresión relativa de cada gen se midió utilizando el método Ct comparativo (∆∆Ct), utilizando la siguiente ecuación: ΔΔCt= (Ct gen interés - Ct gen L8) del tratamiento T1 o T2 - (Ct gen interés- Ct gen L8) del tratamiento control Los datos obtenidos de los parámetros de la calidad del agua, parámetros de producción, metabolitos y expresión de genes del tejido muscular se analizaron 4907 Latin American Journal of Aquatic Research mediante un análisis de varianza (ANDEVA) de una sola vía. Para la confrontación de los resultados y verificación de las diferencias entre los tratamientos, se realizaron pruebas de comparación múltiples de Tukey. Se tomaron como diferencias significativas aquellas con valor de probabilidad P < 0,05. RESULTADOS En cuanto a los parámetros físicos, químicos y calidad del agua, no se observaron diferencias significativas en la concentración de oxígeno disuelto, temperatura, salinidad, pH) (Tabla 1), NAT, NO3 y PO4 (Fig. 1). La concentración de NO2 en el tratamiento control presentó un valor significativamente más alto que el de T1 y no se registraron diferencias respecto a T2 (Fig. 1). Se observaron diferencias en algunos de los parámetros de producción entre los tratamientos (Fig. 2). La ganancia en peso total fue similar entre tratamientos con un rango de 1,40 a 1,45 g. La supervivencia fue mayor en T1 (56%) y T2 (48%), en comparación al control (28%). La biomasa total en T1 (20,72 g) presentó un promedio significativamente mayor al registrado en el tratamiento control (10,60 g), mientras que no se observó una diferencia significativa con respecto a T2 (16,85 g); no se detectaron diferencias entre T1 y T2. El FCA del tratamiento control (4,3) fue significativamente mayor que el registrado en T1 (2,12) y T2 (2,53), los cuales resultaron ser estadísticamente similares entre sí. No se presentaron diferencias significativas en el consumo de alimento entre T1 (44,0g), T2 (42,6g) y C (45,6). Los valores de la TCE fueron de 6,19% día-1 para el control, 6,10% día-1 para T1 y 6,12% día -1 para T2, sin diferencias significativas entre los tratamientos. En relación a la concentración de proteína en el músculo, el valor en T1 (87,3 mg g-1) fue significativamente mayor que en el control (76,4 mg g-1), pero similar al encontrado en T2 (86,1 mg g-1). Para la concentración de glucosa se registraron valores en un rango de 3,40 a 4,10 mg g-1, mientras que para lactato los valores oscilaron entre 1,90 y 2,90 mg g-1. En ambos casos no hubo diferencias significativas entre los tratamientos. La concentración de colesterol del tratamiento control (0,90 mg g-1) fue menor respecto a T1 (1,87 mg g-1), y a T2 (1,65 mg g-1) sin diferencias significativas entre estos últimos (Fig. 3). En relación a la expresión de los genes relacionados con el sistema inmune, se observó una sobreexpresión de LGBP (~2) en los camarones de ambos tratamientos con extracto de L. podocephala, mientras que no se observó un cambio en la expresión de proPO para alguno de ambos tratamientos con respecto al control. (Fig. 4). Figura 1. Parámetros de la calidad del agua en los tratamientos con concentraciones de 0 (C) 1 (T1) y 3 mL L-1 (T2) de extracto acuoso de raíz de L. podocephala. Letras distintas indican diferencias significativas (P < 0,05). NAT: nitrógeno amoniacal total (NH3-NH4). Figura 2. Parámetros de producción de Litopenaeus vannamei en los tratamientos con concentraciones de 0 (C) 1 (T1) y 3 mL L-1 (T2) de extracto acuoso de raíz de L. podocephala. TCE: tasa de crecimiento específico, FCA: factor de conversión alimenticia. Letras distintas indican diferencias significativas (P < 0,05). 908 5 Extracto de pionilla en el cultivo de L. vannamei Tabla 1. Parámetros físicos y químicos monitoreados en las unidades experimentales de los tratamientos con concentraciones de 0 (C) 1 (T1) y 3 mL L-1 (T2) de extracto acuoso de raíz de L. podocephala. Parámetro Oxígeno disuelto (mg·L-1) Temperatura (°C) pH Salinidad C T1 T2 4,8 ± 0,1 27 ± 0,1 6,8 - 7,0 35,5 ± 0,3 4,7 ± 0,1 27 ± 0,5 6,7 - 6,8 35,8 ± 0,1 4,7 ± 0,1 27 ± 0,3 6,7 - 6,8 35,4 ± 0,3 Tabla 2. Iniciadores utilizados para amplificar y medir expresión de genes. Genes Profenoloxidasa Sentido Antisentido LGBP Sentido Antisentido L8 Sentido Antisentido Secuencia de iniciadores (5’-3’) Nº de acceso en Genbank 5´GCCTTGGCAACGCTTTCA3´ 5´CGCGCATCAGTTCAGTTTGT3´ EU373096.1 5´CATGTCCAACTTCGCTTTCAGA3´ 5´ATCACCGCGTGGCATCTT3´ EU102286.1 5´TAGGCAATGTCATCCCCATT3´ 5´TCCTGAAGGGAGCTTTACACG3´ DQ316258 Figura 3. Concentración de metabolitos en tejido muscular del camarón de los tratamientos con concentraciones de 0 (C) 1 (T1) y 3 mL L-1 (T2) de extracto acuoso de raíz de L. podocephala. DISCUSIÓN Durante el experimento los parámetros de calidad del agua como temperatura, salinidad, oxígeno disuelto y pH se mantuvieron estables y dentro de los intervalos que recomiendan diversos autores (Brock & Main 1994; Figura 4. Expresión relativa de los genes que codifican para la proteína unidora de lipopolisacáridos y β-glucanos (LGBP) y profenoloxidasa (proPO) en hepatopáncreas de camarones de los tratamientos con concentraciones de 0 (C) 1 (T1) y 3 mL L-1 (T2) de extracto acuoso de raíz de L. podocephala. La línea semicontinua indica el nivel basal de expresión (1) considerada a partir del control. Martínez-Córdova, 2009). Para el caso de amonio, nitrito, nitrato y fosfato, los valores estuvieron dentro de los rangos adecuados para el desarrollo de L. vannamei 6909 Latin American Journal of Aquatic Research sugeridos por varios autores(Boyd, 1990; ArredondoFigueroa & Ponce-Palafox, 1998; Martínez-Córdova, 2009). La supervivencia registrada por los camarones en todos los tratamientos fue menor al 60%, posiblemente afectada por la falta de sedimento que sirve como refugio para escapar del canibalismo durante la muda, tal como ha sido reportado en estudios anteriores (Arnold et al., 2006a, 2006b). Es probable también, que los acuarios con los que se trabajó no sean adecuados para el desarrollo de la especie considerando que estos organismos son bentónicos y en granjas se encuentran a una profundidad de 1,5 m; aunque el posible efecto negativo fue el mismo para todos los tratamientos. La ganancia en peso total fue baja, lo cual se atribuiría a que el crecimiento se ve limitado como consecuencia del incremento en la densidad de siembra como lo señala Coman et al. (2004). El alto factor de conversión alimenticio obtenido en el tratamiento control es consecuencia de la baja supervivencia que se ve reflejada en una baja biomasa final. Sin embargo, los valores registrados están dentro del rango comúnmente encontrado en granjas comerciales en la región (M. Porchas-Cornejo, com. pers.). Sin embargo, la supervivencia, biomasa final y FCA, fueron mejores en los tratamientos que incluyeron el extracto de la raíz en comparación con el tratamiento control, lo cual indica preliminarmente que el extracto en las concentraciones utilizadas, tiene un efecto positivo en la respuesta productiva del camarón. Aunque la mejor respuesta productiva en camarones expuestos al extracto del tubérculo no se puede asociar a un estímulo sobre el consumo de alimento, es probable que este extracto presente un efecto positivo sobre la condición fisiológica del organismo. Estudios anteriores han demostrado que algunos componentes del tubérculo de L. pododephala tales como (+)curcufenol, exhiben actividad antimicrobiana contra bacterias tipo Vibrio (Ono et al., 2001), que son comunes en el cultivo de camarón. Además, la sobreexpresión de LGBP y proPO en los tratamientos que recibieron extracto de la raíz, se asociaría a una inmunoestimulación por alguno de los componentes del extracto. Las LGBP participan en el reconocimiento de bacterias Gram negativas y hongos, a la vez que estimulan la síntesis de proPO que participa en la melanización, patógenos y tejidos dañados (GollasGalván et al., 1999). Diversos productos derivados de plantas han demostrado tener un efecto inmunoestimulante sobre crustáceos decápodos como los camarones (Citarasu et al., 2006). Las concentraciones de proteína en el musculo de L. vannamei, son similares a los encontrados por Aparicio -Simon et al. (2010), quienes reportaron rangos de 75 a 90 mg g-1 en juveniles de la misma especie. NoreñaRivera (2012) al evaluar el efecto de la inclusión dietaria de un extracto de la raíz de L. podocephala en el cultivo de L. vannamei, encontró valores de proteína de 61,5 mg g-1 con un nivel de inclusión de 0,2%, 64,41 mg g-1 con un nivel de 1% y 77,39 mg g-1 en el tratamiento control. Estos menores valores de proteína, a pesar de considerarse como normales, se atribuyeron a que los organismos estuvieron bajo algún grado de estrés durante el cultivo en laboratorio. La concentración de colesterol registró mayores valores que los reportados por Mercier et al. (2006) para camarones sometidos a estrés por manejo; pero menores a los reportados por Noreña-Rivera (2012) quien obtuvo concentraciones de 0,9; 4,32 y 12,14 mg g-1 para el tratamiento control, con niveles de inclusión de 0,2 y 1% del extracto de pionilla, respectivamente. En dicho estudio se argumenta que es posible que algún componente de la pionilla incentivara un mejor aprovechamiento del colesterol suministrado en el alimento. Los resultados de la presente investigación tienen una tendencia similar, ya que se obtuvo mayor concentración de colesterol y mayor supervivencia en los tratamientos T1 y T2, mientras que los camarones del tratamiento control presentaron una deficiencia de este nutriente, lo cual indica un pobre estado nutricional que pudiera haber sido una de las causas de la mayor mortalidad en este tratamiento. La hipótesis anterior se fundamenta en que el colesterol es un nutriente esencial para el camarón, debido a sus múltiples funciones fisiológicas y metabólicas como componente estructural de membranas, fuente de energía, precursor de hormonas esteroideas y hormonas relacionadas con la muda, entre otros (Bonilla-Gómez et al. 2012); además este no puede ser sintetizado per se por los organismos. El valor de referencia de lactato obtenido para juveniles de L. vannamei es de 0.14 mg g-1 según estudios anteriores (López et al., 2003). Sin embargo, en el presente estudio se registraron valores mucho mayores. Racotta & Palacios (1998) y López et al. (2003) señalan que valores >0,5 mg g-1 de lactato sugieren una condición de estrés. Así como el lactato y la proteína, la glucosa es útil como indicador de estrés en camarones (Mercier et al., 2006, 2009; Ávila-Villa et al., 2012), de lo cual se asume que los mayores valores encontrados en el experimento (3,40 a 4,10 mg g -1), se podrían asociar a condiciones estresantes como el tipo de acuarios utilizados, falta de sedimento, manejo y otros. A diferencia del estudio anterior, realizado por Noreña-Rivera (2012), en que se utilizó el extracto de pionilla en el alimento de L. vannamei, en el presente estudio, el extracto acuoso en la columna de agua no funcionó como aperitivo con solo dos raciones al día. Extracto de pionilla en el cultivo de L. vannamei No obstante, tuvo un efecto positivo en algunos indicadores de la condición fisiológica, inmune y nutricional de los organismos, lo que sugiere que el uso combinado del producto tanto en el alimento como en el agua, pudiera tener un mayor efecto en el mejoramiento del desempeño del camarón en condiciones controladas de cultivo. Por último, una vez demostrado el efecto benéfico del extracto sobre distintas respuestas del camarón, es necesario efectuar estudios cinéticos en relación al comportamiento de biomoléculas y expresión de genes con respecto al tiempo. REFERENCIAS Aparicio-Simón, B., M. Piñon, R. Racotta & I.S. Racotta. 2010. Neuroendocrine and metabolic responses of Pacific whiteleg shrimp Litopenaeus vannamei exposed to acute handling stress. Aquaculture, 298: 308-314. Arnold, S.J., J.M.J. Sellars, P.J. Crocos & G.J. Coman. 2006a. 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Aquaculture, 198: 13-28. Lat. Am. J. Aquat. Res., 43(5): 912-921, 2015 Efecto del ácido fúlvico y la inulina en Litopenaeus vannamei DOI: 10.3856/vol43-issue5-fulltext-11 Research Article Efecto de la inulina y del ácido fúlvico en la supervivencia, crecimiento, sistema inmune y prevalencia de WSSV en Litopenaeus vannamei Anayeli Gutiérrez-Dagnino1, Antonio Luna-González1, Jesús A. Fierro-Coronado1 Píndaro Álvarez-Ruíz1, María del Carmen Flores-Miranda1, Saraí Miranda-Saucedo1 Violeta Medina-Beltrán1 & Ruth Escamilla-Montes1 1 Instituto Politécnico Nacional, Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional-Unidad Sinaloa, Boulevard Juan de Dios Bátiz Paredes 250 Col. San Joachín, C.P. 81101, Guasave, Sinaloa, México Corresponding author: Antonio Luna-González ([email protected]) RESUMEN. Se estudió el efecto del prebiótico inulina y ácido fúlvico, adicionados en el alimento, sobre el crecimiento, supervivencia, prevalencia de WSSV y sistema inmune de Litopenaeus vannamei. Para esto, se realizó un bioensayo, con tratamientos por triplicado, donde se probaron diferentes concentraciones de los aditivos. Se hizo un análisis de WSSV en organismos infectados con una carga viral relativamente alta utilizando la PCR sencilla y anidada. Al final del bioensayo se extrajo la hemolinfa y se estudió el sistema inmune en hemocitos a nivel bioquímico y genético (PCR cuantitativo). El peso final fue similar en todos los tratamientos y la supervivencia estuvo entre 66,7% y 93,3%. La prevalencia de WSSV disminuyó un 13% respecto al control. El número de hemocitos, la actividad de la fenoloxidasa y la concentración de anión superóxido fueron similares en todos los tratamientos. Los aditivos modularon la expresión de los genes transglutaminasa, superóxido dismutasa y profenoloxidasa, pero no la del receptor Toll. Los aditivos no afectan negativamente el crecimiento y protegen al camarón contra WSSV en organismos infectados con una carga viral relativamente alta. No se observó efecto de los aditivos en los efectores del sistema inmune estudiados a nivel bioquímico pero si modularon la expresión de algunos genes relacionados con el sistema inmune en L. vannamei. Palabras clave: Litopenaeus vannamei, inulina, ácido fúlvico, sistema inmune, prebiótico, acuicultura. Effect of inulin and fulvic acid on survival, growth, immune system, and WSSV prevalence in Litopenaeus vannamei ABSTRACT. The effect of inulin and fulvic acid, added in the feed, on growth, survival, WSSV prevalence, and immune system was studied in Litopenaeus vannamei. To the above, a bioassay, with treatments in triplicate, was performed to test different additive concentrations. WSSV analysis was done in organisms infected with a relatively high viral load using single and nested PCR. At the end of the bioassay, hemolymph was extracted and the immune system was studied in hemocytes at biochemical and genetic level (quantitative PCR). The final growth was similar in all treatments and survival was between 66,7% and 93,3%. WSSV prevalence decreased 13% as compared to control. The number of hemocytes, phenoloxidase activity, and superoxide anion concentration were similar in all treatments. Inulin and fulvic acid modulated the expression of transglutaminase, superoxide dismutase, and prophenoloxidase genes, but not the Toll receptor. Additives do not negatively affect growth of white shrimp and they protect them against WSSV when infected with a relatively high viral load. Additives did not affect the immune system effectors studied at biochemical level but they modulated the expression of some immune-related genes in L. vannamei. Keywords: Litopenaeus vannamei, inulin, fulvic acid, immune system, prebiotic, aquaculture. __________________ Corresponding editor: Sandra Bravo 9121 2913 Latin American Journal of Aquatic Research INTRODUCCIÓN A nivel mundial, la acuicultura representa una actividad económica de gran potencial, rentabilidad y en constante expansión. Respecto a la camaronicultura, ésta ha mostrado un constante incremento durante las últimas décadas (Goarant et al., 2006; Tassanakajon et al., 2013). La principal amenaza para el desarrollo de la industria camaronera son las enfermedades infecciosas especialmente las causadas por virus (Lightner, 2011; Tassanakajon et al., 2013). Actualmente, el virus del síndrome de la mancha blanca (WSSV), es una de las enfermedades más devastadoras para los camarones peneidos en cultivo, ocasionando grandes pérdidas económicas (Leu et al., 2009; Lightner, 2011). Como los problemas virales son una amenaza seria para la camaronicultura, es importante el estudio del sistema inmune del camarón, relacionado con la resistencia a los patógenos (Seibert & Pinto, 2012). En la respuesta inmune de los crustáceos se distinguen dos líneas de defensa. La primera es la cutícula, que constituye una barrera física que impide la entrada del patógeno al organismo y la segunda consiste en efectores celulares y humorales que actúan en conjunto para eliminar agentes extraños. La defensa celular incluye todas las reacciones realizadas directamente por los hemocitos como citotoxicidad, coagulación, encapsulación, fagocitosis, melanización y nodulación (Jiravanichpaisal et al., 2006; Sun et al., 2010). Los mecanismos de defensa humorales, incluyen enzimas hidrolíticas, aglutininas, proteínas de la coagulación, péptidos antimicrobianos y radicales libres del oxígeno y nitrógeno (Muta & Iwanaga, 1996; Destoumieux et al., 2000; Fagutao et al., 2012). Contra las infecciones virales no existe la alternativa de los antibióticos, por lo tanto es necesario desarrollar estrategias como la adición de sustancias naturales con actividad antiviral en las dietas de los camarones, pues no sólo proporcionan nutrientes esenciales para el crecimiento y desarrollo del organismo cultivado, sino que también pueden influir en la salud de los organismos y su resistencia al estrés (Gatlin, 2002). Un grupo de moléculas que ha demostrado numerosos efectos benéficos en los animales terrestres, así como en algunos animales acuáticos, se conocen como prebióticos, polisacáridos no digeribles adicionados al alimento que influyen benéficamente en el organismo mediante la estimulación del crecimiento y/o actividad metabólica de una/o varias cepas de bacterias benéficas (probióticos) en el intestino (Gibson & Roberfroid, 1995; Li et al., 2007). Además, algunos prebióticos como los fructo-oligosacáridos (Li et al., 2007) y la inulina (Luna-González et al., 2012; Partida- Arangure et al., 2013) aumentan la capacidad inmune de L. vannamei. El ácido fúlvico es otro compuesto que puede ser incorporado a las dietas, que se forma a partir de materia orgánica en descomposición y tiene la propiedad de formar compuestos de bajo peso molecular con iones de carga positiva, un proceso conocido como quelación. El ácido fúlvico adicionado al agua de cultivo mejora el crecimiento y la respuesta inmune en peces, también promueve una curación más rápida de los peces infectados con ectoparásitos y la eliminación de metales y sustancias químicas en el agua (Meinelt et al., 2004). En el presente estudio se evaluó el efecto de la inulina y el ácido fúlvico, adicionados en el alimento, en la supervivencia, crecimiento, sistema inmune y prevalencia de WSSV en L. vannamei, cultivado en el laboratorio. MATERIALES Y MÉTODOS Colecta y mantenimiento de camarones Se colectaron 170 camarones (12,74 ± 0,84 g) de una granja del municipio de Guasave (Sinaloa, México) y se aclimataron por 4 días colocándolos en tanque de cultivo (120 L de capacidad) con 80 L de agua de mar filtrada (20 µm) y salinidad de 30. Los camarones se mantuvieron a temperatura ambiente y con aireación constante. En cada tanque se colocaron 10 organis-mos y se alimentaron ad-libitum dos veces al día (9:00 y 17:00 h) con alimento comercial. Se realizó un análisis preliminar de PCR a 12 camarones para evaluar el estatus del WSSV en los organismos experimentales. Incorporación de la inulina y ácido fúlvico en el alimento El alimento comercial (Camaronina ®, Purina, 35% de proteína) se pulverizó en un molino de café y se le agregó la inulina de agave tequilero (IIDEAL, S.A. de C.V., Guadalajara, Jalisco, México) y ácido fúlvico (Fertichem, Cuernavaca, Morelos, México). Se elaboró una pasta con la mezcla, añadiendo 410 mL de agua destilada y 40 g de grenetina a cada kg de alimento. Los pellets se hicieron en un molino de carne y se secaron a temperatura ambiente con un ventilador durante 24 h. Se preparó alimento para 30 días y se almacenó a 20°C. Para el tratamiento control se sustituyó la mezcla de aditivos (inulina y ácido fúlvico) por α-celulosa (Sigma, St. Louis, MO, USA). La longitud y diámetro final del pellet fue de 5 y 3 mm, respectivamente. Efecto del ácido fúlvico y la inulina en Litopenaeus vannamei Extracción de ADN para WSSV La extracción del ADN se realizó con DNAzol (Invitrogen, Carlsbad, CA, USA), utilizando 100 mg de tejido (pleópodos) y siguiendo las indicaciones del fabricante con algunas modificaciones. El tejido en DNAzol (500 µL) se maceró con un pistilo, se incubó por 30 min y se centrifugó a 10,000 g, durante 10 min. Se recuperaron 300 µL del sobrenadante, se adicionaron 250 µL de etanol absoluto frío (-20°C), se mezcló por inversión y se dejó reposar por 3 min. La muestra se centrifugó a 7,500 g, durante 5 min y se descartó el sobrenadante. La pastilla se lavó con 300 µL de etanol al 75% frío y se centrifugó a 13,000 g durante 5 min. Posteriormente, se descartó el etanol y se secó a temperatura ambiente (5 a 15 min) y luego, se agregó 30 µL de buffer TE pH 8,0 (tris 10 mM, EDTA 1 mM). La cantidad y calidad del ADN se determinó en un nanofotómetro Pearl (IMPLEN, Inc., Westlake Village, CA, USA) a 260/280 y 260/230 nm. Antes de los análisis de PCR, las muestras se diluyeron con buffer TE para obtener una concentración de 100 ng µL-1. Análisis de WSSV Antes de los bioensayos, los camarones fueron analizados, mediante una PCR sencilla y anidada, para determinar si eran portadores del WSSV. Para la PCR sencilla se utilizaron los oligos WSSV1 out (sentido: 5’-ATC ATG GCT GCT TCA CAG AC-3’) y WSSV2 out (contrasentido: 5’-GGC TGG AGA GGA CAA GAC AT-3’). Para la PCR anidada se utilizaron los oligos WSSV1 in (sentido: 5’-TCT TCA TCA GAT GCT ACT GC -3’) y WSSV2 in (contrasentido: 5’TAA CGC TAT CCA GTA TCA CG-3’) (Kimura et al., 1996), que amplifican fragmentos de 982 y 570 pb, respectivamente. La mezcla de reacción se realizó en tubos Eppendorf de 0,2 mL e incluyó 18,75 µL de H2O, 2,5 µL de búfer de reacción 10X (Bioline, Tauton, MA, USA®), 1,0 L de MgCl2 (50 mM; Bioline), 0,5 µL de dNTPs (2,5 mM de cada uno; Bioline), 0,5 µL de cada oligo (10 µM; Sigma-Genosys®), 0,25 µL de Taq polimerasa (5 U µL-1, Bioline) y 1 L de ADN (100 ng) para un volumen total de 25 L. La amplificación se realizó en un termociclador BIOER LifePro®, usando el siguiente programa: desnaturalización inicial a 95C por 4 min, seguida de 35 ciclos de 30 s a 95C, 30 s a 55C, 2 min a 72C, y una extensión final a 72C por 4 min. Los fragmentos amplificados se visualizaron bajo luz UV (DigiDoc-It®, UVP, Upland, CA, USA) en un gel de agarosa al 1%, teñido con bromuro de etidio (0,5 µg mL-1). En la PCR anidada se redujo a 45 s el tiempo de elongación (72°C). Control interno de la PCR (gen GAPDH) Para confirmar la existencia y calidad del ADN se realizó la amplificación del gen GAPDH que codifica 914 3 la enzima gliceraldehído-3-fosfato deshidrogenasa en L. vannamei. Este gen funciona como un control interno del ADN genómico del camarón (Tang et al., 2000). Se utilizaron los oligos reportados por Tang et al. (2000) (GAPDH298F 5’-TCA CCG TCT TCA ACG AGA TG-3’ y GAPDH298R 5’-ACC CTC CAG CAT CTC GAA CT-3’), que amplifican un fragmento de 298 pb. La mezcla de reacción y programa de amplificación fueron los mismos de la PCR para WSSV. Preparación del inóculo viral Se preparó el inóculo a partir de tejido branquial y muscular de camarones infectados con una carga viral baja de WSSV (detectados en el laboratorio por PCR anidada). Se maceraron los tejidos por 5 min con un homogenizador Pellet Pestle motor (Kontes, NY, USA) y se mezclaron con solución salina (NaCl 2%) en una proporción 1:10 (p/v). La mezcla resultante se dividió en alícuotas de 20 mL colocadas en tubos Falcón y se centrifugaron a 3,900 g durante 10 min a 4ºC. Posteriormente, se repartió el sobrenadante en tubos Eppendorf (1,5 mL en cada tubo) y se centrifugó a 14,000 g a 4oC por 20 min. El sobrenadante fue filtrado (0,45 µm) y almacenado en alícuotas a -70ºC. Elaboración de pasta infectada con WSSV Se infectaron camarones juveniles (5-12 g) inyectando 30 µL de inóculo viral por vía intramuscular en el segundo segmento abdominal utilizando una jeringa para insulina. Se registró la evolución de la enfermedad dos veces al día. Los camarones moribundos (24-48 h) se sacrificaron, se tomó una muestra de tejido para verificar la presencia de WSSV por PCR y se almacenaron a -80ºC. Posteriormente, se tomó el músculo abdominal y se cortó en trozos muy finos con un bisturí hasta formar una pasta. Se extrajeron las branquias de los organismos con unas pinzas de disección y se mezclaron de manera homogénea con el músculo. Se determinó la carga viral alta en la pasta mediante PCR sencillo (Lo et al., 1996a, 1996b) y se congeló a -70°C hasta su uso. Se realizó el mismo procedimiento en otro grupo de camarones, pero se sacrificaron a las 10 h antes de presentar los signos de la enfermedad (letargia, intestino vacío, nado errático). Se determinó la carga viral baja en la pasta mediante PCR anidada (Lo et al., 1996a, 1996b) y se congeló a -70°C hasta su uso. Bioensayo Se realizó un bioensayo de 30 días en tanques de plástico (120 L) sin arena con 80 L de agua de mar filtrada (20 µm), salinidad de 30 y aireación constante (sistema abierto). En cada tanque se colocaron 10 4915 Latin American Journal of Aquatic Research individuos aparentemente sanos con peso promedio de 12,74 ± 0,84 g. En el día 10, los camarones se alimentaron con pasta de tejido infectado de camarón con carga viral baja (2 g tanque-1). En el día 16 se alimentaron con una pasta de tejido infectado con carga viral alta (2 g tanque-1). En el día 17 se adicionaron 800 μL de inóculo viral en el agua de cada tanque. Los cuatro tratamientos se realizaron por triplicado: I) Camaronina + celulosa (control); II) Camaronina + inulina (0,625 g kg alimento-1) + ácido fúlvico (0,125 g kg alimento-1); III) Camaronina + inulina (1,25 g kg alimento-1) + ácido fúlvico (0,25 g kg alimento-1); IV) Camaronina + inulina (2,50 g kg alimento-1) + ácido fúlvico (0,5 g kg de alimento-1). La alimentación con la dieta comercial se realizó durante los 30 días del bioensayo de acuerdo al porcentaje de biomasa (tabla de Purina), dos veces al día (9:00 y 17:00 h). Se registró diariamente la temperatura y cada 3 días el oxígeno, salinidad y pH. Se evaluaron las concentraciones de nitritos, nitratos y amonio al principio y al final del bioensayo (Strickland & Parsons, 1972). Los parámetros físicos y químicos, y de calidad de agua se mantuvieron dentro de los intervalos óptimos según Brock & Main (1994) durante los 30 días que duró el bioensayo. Se eliminaron los sólidos sedimentados cada 3 días por sifoneo, recuperando el agua perdida. Se realizó un recambio del 50% de agua cada 5 días. El agua del recambio fue clorada y desechada. El incremento en peso se determinó semanalmente para ajustar la ración del alimento. La supervivencia (%) se determinó diariamente. Al final se registraron los pesos, parámetros del sistema inmune y prevalencia de WSSV (porcentaje de organismos infectados por tratamiento). Tasa de crecimiento específico (TCE) Al final del bioensayo se determinó la tasa de crecimiento específico (TCE) utilizando la siguiente fórmula (Ziaei-Nejad et al., 2006): TCE (% día-1) = 100 (ln W2 – ln W1)/t donde: W2 es el peso final, W1 el peso inicial y t es el número de días de cultivo. Parámetros del sistema inmune Obtención de la hemolinfa Este proceso se realizó manteniendo todos los componentes en hielo. Se extrajo la hemolinfa de camarones experimentales (8 por estanque, 24 por tratamiento) con jeringas para tuberculina (27G x 13 mm) del sinus ventral del camarón (primer segmento abdominal). Antes de la extracción, la jeringa se cargó con una solución isotónica para camarón y un anticoagulante con citrato trisódico pH 7,5 (citrato trisódico 27 Mm, NaCl 385 mM, glucosa 115 mM) en una proporción 2:1 (2 volúmenes de anticoagulante por cada volumen extraído de hemolinfa, 600 µL:300 µL) (Huang et al., 2010). La muestra de hemolinfa se colocó en tubos Eppendorf de 1,5 mL. Se utilizaron tres, dos y tres camarones por estanques para el anión superóxido, expresión de genes y actividad de la fenoloxidasa, respectivamente. Para el conteo de hemocitos se utilizaron 50 µL de la hemolinfa destinada para medir la actividad de la fenoloxidasa antes de centrifugarla. Separación de plasma y obtención del sobrenadante del lisado de hemocitos (SLH) Se separaron los hemocitos del plasma centrifugando a 800 g por 10 min a 4°C (Hernández-López et al., 1996). El plasma se colocó en otro tubo y se almacenó a -80°C hasta su análisis. Al paquete celular se adicionó 1 mL de anticoagulante frío y se centrifugó nuevamente a 800 g por 10 min a 4°C. Se descartó el sobrenadante y se adicionó 300 µL de búfer de fosfato de potasio 0,1 M pH 7,6 (86,6 mL de K2HPO4 1M, 13,4 mL de KH2PO4). Para lisar los hemocitos se centrifugó a 14,000 g por 10 min a 4°C, se recuperó el SLH y se guardó a -80°C hasta su análisis. Las muestras de plasma y SLH se utilizaron para el análisis de la actividad de la fenoloxidasa. Conteo total de hemocitos (CTH) Para el CTH se tomaron 50 µL de hemolinfa y se mezclaron con 150 µL (1:3) de formol al 6%. El conteo se realizó individualmente en una cámara Neubauer. Actividad de la fenoloxidasa La actividad de la fenoloxidasa (FO) se determinó según Hernández-López et al. (1996). La actividad de la FO presente en el plasma se midió espectrofotométricamente por la formación de dopacromo a partir de L-dihidroxifenilalanina (L-Dopa, Sigma, St. Louis, MO, USA). A 50 µL de muestra, se adicionaron 50 µL de búfer de fosfato de potasio 0,1 M (pH 7,6) y 50 µL de L-Dopa [3 mg mL-1 en buffer de fosfato de potasio (0,1 M pH 6,6 38,1 mL de K2HPO4 1M, 61,9 mL de KH2PO4 1M,)]. Se incubó durante 10 min a 37°C y se determinó la absorbancia a 492 nm. Para activar la profenoloxidasa (proFO) en el SLH se tomó 50 µL de muestra, se adicionó 50 µL de tripsina (1 mg mL-1) en buffer de fosfato de potasio (0,1 M, pH 7,6) y se incubó por 30 min a 37°C. La actividad de la FO en el SLH se determinó como se describió anteriormente para el plasma. Se utilizó como blanco 100 µL de buffer de fosfato de potasio y 50 µL de L-Dopa. Las muestras individuales de nueve camarones se procesaron por triplicado. Efecto del ácido fúlvico y la inulina en Litopenaeus vannamei Anión superóxido intracelular El anión superóxido se cuantificó mediante la metodología de Song & Hsieh (1994). La hemolinfa se centrifugó a 800 g, por 5 min a 4°C. Posteriormente, se descartó el sobrenadante y los hemocitos se lavaron dos veces con 900 µL de anticoagulante. Se centrifugó nuevamente a 800 g, por 5 min a 4°C y se desechó el sobrenadante. Los hemocitos se tiñeron con 100 µL de una solución de nitroblue tetrazolium al 0,3% (NBT, Sigma®) durante 30 min a 37ºC. La reacción de tinción se finalizó eliminando la solución NBT y adicionando 100 µL de metanol absoluto. Después de tres lavados con metanol al 70%, los hemocitos fueron secados a temperatura ambiente por 30 min. Se adicionó 120 μL de KOH (2 M) y 140 μL de dimetil sulfóxido (DMSO, sigma ®) para disolver el formazán citoplasmático. Se colocaron 200 µL de cada muestra por triplicado en una microplaca y se utilizó como blanco 200 µL de la mezcla (300 µL de KOH y 350 µL de DMSO). La densidad óptica del formazán disuelto se cuantificó a 630 nm. Extracción de ARN y síntesis de ADNc Para evaluar la expresión de los genes en hemocitos, se separaron del plasma por centrifugación (800 g por 10 min a 4°C) y se adicionó 300 µL de Trizol para extraer el ARN total de acuerdo al protocolo del fabricante (Invitrogen, Carlsbad, CA, USA). La concentración y pureza del ARN total se determinó midiendo la absorbancia a 260/280 nm en un nanofotómetro Pearl (Implen®, Westlake Village, CA, USA) y se almacenó a -70ºC hasta su uso en la transcripción reversa. Para sintetizar el ADN complementario (ADNc), el ARN se trató con ADNsa 1 (1 U µL-1, Sigma) y se utilizó la transcriptasa reversa Improm II siguiendo la metodología del fabricante (Promega®, Madison, WI, USA), a partir de 500 ng de ARN total con oligo dT20. El ADNc se resuspendió en 80 µL de agua ultrapura y se almacenó a -70ºC hasta el análisis de PCR en tiempo real. Expresión de genes mediante PCR en tiempo real Se evaluó la expresión relativa de genes del sistema inmune del camarón en hemocitos. Los resultados fueron normalizados contra la expresión del gen que codifica para la subunidad ribosomal 18s como gen de referencia. Los oligos (Sigma Genosys®) específicos se muestran en la Tabla 1. Las amplificaciones se realizaron en un equipo CFX96 Touch Real-Time System (BIO-RAD®) utilizando el software CFX Manager versión 3.0 (BIO-RAD) para la obtención de los datos. Las amplificaciones se efectuaron por duplicado en placas de 96 pozos con un volumen de reacción final de 15 µL, conteniendo 7,5 µL de PCR Master Mix 2x [3 9165 µL de buffer de reacción 5x; 1,5 µL de MgCl 2 25 mM; 0,3 µL de dNTPs 10 mM; 0,75 µL de EvaGreen 20x (Biotium In., Hayward, CA, USA); 0,15 µL de Go Taq; 1,8 µL de agua ultrapura], 0,7-1,0 µL de primers [sentido y contrasentido, 10 µM c/u (Sigma Genosys®I],1,5-1,8 µL de agua ultrapura y 5 µL de templado (ADNc). Las condiciones de amplificación fueron: desnaturalización inicial a 95°C por 3 min, seguida de 40 ciclos a 95°C por 10 s, 60°C por 15 s, 72°C por 30 s y un paso adicional de 79°C por 5 s para adquirir la fluorescencia. Después de cada reacción, se realizó un análisis de disociación (Curva de Melting) de 65 a 95°C, con un aumento de 0,5°C cada 5 s para confirmar la ausencia de dímeros de oligos o fragmentos inespecíficos. La eficiencia de las amplificaciones se determinó mediante una curva de calibración, calculando una pendiente con cinco diluciones seriales (factor 5) de una mezcla representativa, formada con 5 µL de cada ADNc del experimento. La cantidad de oligos para cada gen fue optimizada realizando curvas con diferentes cantidades de oligos y tomando como referencia la mejor eficiencia de reacción. Adicionalmente, para corregir pequeñas variaciones de Cq entre una y otra placa, se preparó un pool de reacciones con una misma muestra como templado (ajustadores), se formaron alícuotas de 50 µL y se congelaron a -20°C. Se descongeló una alícuota para cada placa y se corrieron tres muestras de 15 µL. Finalmente, se sumó a cada valor en la placa, la diferencia entre el promedio general de los ajustadores menos el promedio de ajustadores en cada placa. Los valores de Cq se transformaron a cantidades relativas usando la fórmula de Pfaffl. La expresión relativa se calculó normalizando contra la cantidad relativa en el tratamiento control (como un calibrador con nivel de expresión de 1) (Pfaffl, 2001). Análisis estadístico Los resultados en porcentaje se transformaron a arcoseno √%/100 para normalizar su distribución y se sometieron a un análisis de varianza (Ostle, 1965). Los datos de crecimiento, supervivencia (%) y sistema inmune se analizaron con un ANDEVA de una vía para determinar diferencias significativas entre tratamientos (P < 0,05) y una prueba de Tukey (HSD) para identificar la naturaleza de estas diferencias (P < 0,05). RESULTADOS Supervivencia y prevalencia de WSSV de los camarones experimentales La supervivencia obtenida fue de 66 a 93% mientras que la prevalencia de WSSV varío entre 53,3 y 66,7% 6917 Latin American Journal of Aquatic Research Tabla 1. Oligos utilizados en el estudio de expresión de genes con PCR cuantitativa (Wang et al., 2010). Gen Secuencia de los oligos 18s ARN (control interno) Profenoloxidasa (proFO) Transglutaminasa (TGasa) Superóxido Dismutasa (SOD) Toll receptor (LvToll) F 5’-AGCAGGCTGGTTTTTGCTTA-3’ R 5’-ATGCTTTCGCAGTAGGTCGT-3’ F 5'-GAGATCGCAAGGGAGAACTG-3' R 5'-CGTCAGTGAAGTCGAGACCA-3' F 5'-CCTCAGGATCTCCTTCACCA-3' R 5'-TTGGGAAAACCTTCATTTCG-3' F 5'-ATCCACCACACAAAGCATCA-3' R 5'-AGCTCTCGTCAATGGCTTGT-3' F 5'-ATGTGCGTGCGGATACATTA-3' R 5’-GGGTGTTGGATGTCGAGAGT3' Tabla 2. Supervivencia, tasa de crecimiento especifico, prevalencia de WSSV, conteo total de hemocitos, anión superóxido y actividad de la fenoloxidasa en el camaron blanco L. vannamei. Tratamientos: I) Control; II) inulina (0,625 g kg-1 alimento-1) + ácido fúlvico (0,125 g kg alimento-1); III) inulina (1,25 g kg alimento-1) + ácido fúlvico (0,25 g kg alimento-1); IV) inulina (2,50 g kg alimento-1) + ácido fúlvico 0,5 g kg alimento-1). Los valores se indican como promedio ± EE. TCE: tasa de crecimiento específico. SLH: sobrenadante del lisado de hemocitos. FO: fenoloxidasa. Parámetro estudiado Supervivencia (%) Prevalencia de WSSV (%) TCE (% diario) Hemocitos mL-1 (x 106) Anión superóxido (Abs 630 nm) FO total (Abs 492 nm) Tratamientos I 83,30 ± 16,66 66,66 ± 1,44 0,33 ± 0,04 27,73 ± 2,16 1,17 ± 0,09 2,04 ± 0,08 (Tabla 2). No se observaron diferencias significativas de la supervivencia en los tratamientos (P > 0,05). Tasa de crecimiento específico La TCE (% diario) en los tratamientos estuvo entre 0,25 y 0,35. No hubo diferencias significativas (P > 0,05) entre tratamientos (Tabla 2). Conteo total de hemocitos (CTH) Los resultados mostraron que el número de hemocitos por mililitro de hemolinfa fue similar entre los tratamientos (P > 0,05) (Tabla 2). Actividad total de la fenoloxidasa (plasma + SLH) No se observaron diferencias significativas en la actividad de la fenoloxidasa en los tratamientos (P > 0,05) (Tabla 2). Anión superóxido en SLH Los resultados no mostraron diferencias significativas en la concentración del anión superóxido entre los tratamientos (P > 0,05) (Tabla 2). II 66,67 ± 17,63 55,00 ± 2,60 0,35 ± 0,08 28,90 ± 2,20 1,22 ± 0,05 2,23 ± 0,14 III 86,67 ± 8,81 55,00 ± 1,75 0,31 ± 0,05 25,17 ± 1,28 1,26 ± 0,07 2,33 ± 0,07 IV 93,33 ± 8,16 53,33 ± 0,71 0,25 ± 0,02 27,69 ± 3,50 1,32 ± 0,07 2,13 ± 0,06 Análisis de la expresión de genes del sistema inmune Los resultados de expresión muestran que la inulina y el ácico fúlvico modularon significativamente la expresión de los genes profenoloxidasa, SOD y transglutaminasa entre los tratamientos (Tabla 3). La expresión de los genes mostró una tendencia a disminuir en el tratamiento IV (mayor cantidad de aditivos) respecto a los tratamientos I y II. DISCUSIÓN No existen reportes sobre el efecto de la mezcla de inulina y ácido fúlvico, adicionados a la dieta, en el crecimiento (TCE), supervivencia, sistema inmune y prevalencia de WSSV en L. vannamei. En este estudio se observó que la TCE no aumentó significativamente en los camarones alimentados con inulina y ácido fúlvico, coincidiendo con los resultados reportados por Li et al. (2007) y Luna-González et al. (2012), quienes probaron fructo-oligosacáridos e inulina en L. vannamei, respectivamente. Sin embargo, los resultados contrastan con los de Zhou et al. (2007) quienes observaron un aumento significativo en el cre- Efecto del ácido fúlvico y la inulina en Litopenaeus vannamei 9187 Tabla 3. Expresión relativa de genes relacionados con el sistema inmune de L. vannamei alimentado con inulina y ácido fúlvico. Tratamientos: I) Control; II) inulina (0,625 g kg alimento-1) + ácido fúlvico (0,125 g kg alimento-1); III) inulina (1,25 g kg alimento-1) + ácido fúlvico (0,25 g kg alimento-1); IV) inulina (2,50 g kg alimento-1) + ácido fúlvico 0,5 g kg alimento-1). La expresión del gen 18S fue usada como control interno (gen de referencia). Letras distintas indican diferencias significativas (P < 0,05). Barras de error = promedio ± EE. Genes Transglutaminasa Receptor Toll Superóxido dismutasa Profenoloxidasa I 1b 1 1ab 1ab Expresión relativa a 18 S II III 1,50 ± 0,14a 1,17 ± 0,11ab 0,69 ± 0,06 0,63 ± 0,15 1,32 ± 0,14a 0,76 ± 0,03b 1,62 ± 0,24a 1,33 ± 0,20ab cimiento de L. vannamei alimentado con fructooligosacáridos (0,4 g kg alimento-1) y también con los obtenidos por Meinelt et al. (2004) quienes alimentaron al pez cola de espada Xiphophorus helleri con substancias húmicas (ácidos húmicos y fúlvicos) y lograron aumentar su crecimiento significativamente. Las diferencias en los resultados se explicarían por el tipo y cantidad de prebiótico utilizado, cantidad de ácido fúlvico probado y mezcla del mismo con la inulina. Respecto a la supervivencia, ésta fue mejor en el tratamiento con la concentración más alta de aditivos aunque la diferencia no fue significativa respecto al control y los otros tratamientos. Los resultados son similares a los obtenidos por Li et al. (2007) quienes obtuvieron supervivencias altas pero similares entre tratamientos en L. vannamei alimentado con fructooligosacáridos adicionados en la dieta (0,025; 0,0500; 0,075; 0,100; 0,200; 0,400 y 0,800%). Sin embargo, es importante mencionar que, a diferencia de este trabajo, los investigadores mencionados no infectaron a los camarones con WSSV. La duración del bioensayo fue de 30 días y la diferencia en la prevalencia de WSSV entre el tratamiento IV y el control fue de 13,3% en camarones infectados con una carga viral relativamente alta (PCR sencilla: >1000 copias de ADN viral, Lo et al., 1996a, 1996b), lo que contrasta con el 41% reportado por Luna-González et al. (2012) en la misma especie, utilizando como aditivo inulina, en un bioensayo de 60 días con camarones que venían infectados con baja carga viral (PCR anidada: 10-50 copias de ADN viral, Lo et al., 1996a, 1996b) desde la granja y no se reinfectaron en el laboratorio. Por otro lado, el ácido fúlvico tiene propiedades antivirales (Van Rensburg et al., 2002), debido a que bloquea la entrada de los virus a la célula al interactuar con lípidos o carbohidratos o ambos de glucoproteínas de superficie de virus envueltos (Kotwal, 2008). Por lo anterior, es probable que el efecto en la disminución en la prevalencia de WSSV haya sido inferior a lo reportado por Luna- IV 0,45 ± 0,08c 0,96 ± 0,10 0,71 ± 0,10b 0,64 ± 0,22b González et al. (2012) debido a la menor duración del bioensayo, a la mayor cantidad de partículas virales en los camarones debido a la reinfección y/o a la mutua neutralización entre la inulina (carbohidrato) y el ácido fúlvico. El estudio del sistema inmune del camarón es un elemento clave para establecer estrategias para el control de enfermedades (Peña et al., 2013; Tassanakajon et al., 2013). Al respecto, los hemocitos son responsables de la coagulación, endurecimiento del exoesqueleto y eliminación de materiales extraños (Song & Hsieh, 1994). Un incremento en el número de hemocitos aumenta la respuesta inmune de los crustáceos durante los periodos de estrés y los hace más resistentes a las enfermedades (Le Moullac et al., 1998). En el bioensayo, el número total de hemocitos fue similar en todos los tratamientos, lo que coincide con lo reportado por Luna-González et al. (2012), quienes no encontraron diferencias significativas entre tratamientos cuando alimentaron camarones blancos sólo con inulina (2,5 g kg alimento-1). Aunque no hubo un aumento de los hemocitos respecto al control, no se observó un efecto negativo de los aditivos ya que Campa-Córdova et al. (2002) mencionan que la disminución en el número de hemocitos, está asociada a la susceptibilidad momentánea de los camarones a los patógenos. El anión superóxido se produce durante el proceso de fagocitosis en los hemocitos, es una molécula oxidante y tiene efecto bactericida (Wang et al., 2010). En el bioensayo no se presentaron diferencias significativas entre los tratamientos en la concentración del anión superóxido. Contrariamente a lo encontrado, Ibrahem et al. (2010) mencionan que la inulina (5 g kg alimento-1) incrementó significativamente el estallido respiratorio (fagocitosis) en la tilapia Oreochromis niloticus, en comparación con el grupo control. En L. vannamei, Li et al. (2007) mencionan que la adición de FOS de cadena corta (0,1 y 0,8%) en el alimento, incrementa significativamente el estallido respiratorio 8919 Latin American Journal of Aquatic Research de los hemocitos, lo cual se asocia a un aumento en la generación de anión superóxido durante el proceso de fagocitosis. A nivel molecular, se observó una disminución en la expresión del gen de la SOD (que tiene como sustrato al anión superóxido) en los tratamientos III y IV (con mayor concentración de aditivos), respecto al tratamiento II (con menor concentración de aditivos). Es probable que la invariabilidad del anión superóxido y la disminución en la expresión del gen SOD se deba al ácido fúlvico, ya que algunos resultados obtenidos en ratones indican que este ácido secuestra radicales libres, inhibe la fagocitosis específica y funciones celulares linfocíticas (Van Rensburg et al., 2001). El sistema profenoloxidasa (proFO) es uno de los mecanismos defensivos más importantes en crustáceos (Okumura, 2007). En L. vannamei, el sistema proFO está involucrado en la defensa inmune contra Vibrio alginolyticus (Yeh et al., 2009), pero se inhibe por la infección con WSSV (Ai et al., 2008, 2009). La actividad de la fenoloxidasa fue similar en todos los tratamientos. Lo anterior no coincide con lo reportado por Luna-González et al. (2012) quienes encontraron un aumento significativo en la actividad de FO en los camarones infectados con baja carga de WSSV y tratados con inulina (2,5 g kg alimento-1) respecto al control sin el prebiótico. En este estudio, se observó una disminución significativa en la expresión del gen en el tratamiento con la mayor concentración de aditivos (tratamiento IV), respecto al de menor concentración (tratamiento II). Es probable que, junto con el efecto inhibidor de WSSV, la disminución en la expresión del gen se deba al ácido fúlvico, ya que como se mencionó anteriormente, éste interactúa con lípidos y carbohidratos, como la inulina. Los resultados del análisis bioquímico y molecular son diferentes pero hay que considerar que el sistema proFO se almacena en gránulos dentro de los hemocitos. La proteína de la coagulación (PC) se encuentra en el plasma en crustáceos decápodos y su polimerización se realiza mediante la acción de la enzima transglutaminasa en presencia de calcio. La transglutaminasa se encuentra en el interior de las células hialinas del camarón y se libera al plasma por daño tisular o como una repuesta de los hemocitos ante la presencia de lipopolisacáridos y β-1,3-glucanos (Yeh et al., 1998; Montaño-Pérez et al., 1999; Fagutao et al., 2012). Según Fagutao et al. (2012) el silenciamiento génico de la transglutaminasa hace al camarón más susceptible a infecciones bacterianas y virales; por tanto, esta enzima es un componente esencial de su sistema inmune y está implicada en la regulación de otros genes (crustina y lisozima). En este trabajo, el gen de la transglutaminasa presentó una expresión signifi-cativamente mayor en el tratamiento II (menor concentración de aditivos) respecto al control sin aditivos y al tratamiento IV (mayor concentración de aditivos). Los resultados indican una mayor capacidad de coagulación en el tratamiento II respecto al I y IV y una mejor respuesta ante WSSV. Sin embargo, el porcentaje de supervivencia en el tratamiento II fue menor respecto al tratamiento IV. En relación con la expresión del gen LvToll, no hubo diferencias significativas entre los tratamientos. El sistema inmune innato identifica los agentes infecciosos mediante receptores celulares, los cuales son proteínas que se unen a macromoléculas de patógenos microbianos. La familia de receptores, llamada Toll, fue originalmente identificada y descrita en la mosca de la fruta (Drosophila sp.) como receptora necesaria para el desarrollo dorso-ventral durante la embriogénesis, y en adultos como activadores de la respuesta inmune antifungal (Hashimoto et al., 1988). Los resultados muestran que los aditivos probados no parecen interactuar con los receptores Toll de los hemocitos. En conclusión, la mezcla de inulina y ácido fúlvico en el alimento disminuyen la prevalencia de WSSV en camarones infectados con una carga viral relativamente alta. 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Effects of dietary short-chain fructooligosaccharides on intestinal microflora, survival and growth performance of juvenile white shrimp, Litopenaeus vannamei. J. World Aquacult. Soc., 38(2): 296-301. Ziaei-Nejad, S., M.H. Rezaei, G.A. Takami, D.L. Lovett, A.R. Mirvaghefi & M. Shakouri. 2006. The effect of Bacillus spp. bacteria used as probiotics on digestive enzyme activity, survival and growth in the Indian white shrimp Fenneropenaeus indicus. Aquaculture, 252: 516-524. Lat. Am. J. Aquat. Res., 43(5): 922-935, 2015 DOI: 10.3856/vol43-issue5-fulltext-12 Metazoan meiofauna assemblages off central Chile 9221 Research Article Composition and vertical distribution of metazoan meiofauna assemblages on the continental shelf off central Chile Eulogio Soto1, Williams Caballero1 & Eduardo Quiroga2 Facultad de Ciencias del Mar y de Recursos Naturales, Universidad de Valparaíso P.O. Box 5080, Reñaca, Viña del Mar, Chile Escuela de Ciencias del Mar, Pontificia Universidad Católica de Valparaíso P.O. Box 1020, Valparaíso, Chile 1 Corresponding author: Eulogio Soto ([email protected]) ABSTRACT. A quantitative study of metazoan meiofauna was carried out in Valparaiso Bay (33°S 71°W) which is affected by seasonal hypoxia in central Chile. The contents of bottom water, dissolved oxygen (BWDO), organic carbon, chloroplast pigments and composition of stable carbon isotope (δ13C) in the sediment were used as a measure of the contribution of primary production in the water column, which accumulates in the sediment. Meiofauna abundances in the three sampling stations (80-140 m depth) ranged from 2.218 ± 643 to 1.592 ± 148 ind 10 cm-2. Nine upper metazoan meiofauna groups were recorded, with nematodes as the dominant group, contributing with more than 95% of total abundances. The abundance vertical distribution was concentrated in the first layers of sediment in most groups except Acari and nauplii larvae. Canonical correspondence analysis revealed significant correlations (P < 0.05) between the meiofauna abundance and organic content, depth and redox potential from sediments. These results represent a first approach to understanding the ecology of meiofaunal assemblages in the Valparaiso Bay and may be useful as a baseline for future comparisons and descriptions of the ENSO (El Niño Southern Oscillation) and seasonal variations of these unknown benthic communities. Keywords: meiofauna, nematodes, abundance, sediment, Valparaiso Bay, southeastern Pacific. Composición y distribución vertical de los ensambles de meiofauna metazoaria en la plataforma continental frente a Chile central RESUMEN. Se realizó un estudio cuantitativo de la meiofauna metazoaria en la Bahía de Valparaíso (33°S, 71°W), afectada por hipoxia estacional en Chile central. Los contenidos de oxígeno disuelto en el agua de fondo, carbono orgánico, pigmentos cloroplásticos y composición de isotopos estables de carbono en el sedimento (δ13C) se usaron como una medida del aporte de producción primaria en la columna de agua, que se acumula en el sedimento. La abundancia de la meiofauna en las tres estaciones de muestreo (80-140 m de profundidad) varió de 2.218 ± 643 a 1.592 ± 148 ind 10 cm-2. Se registraron nueve grupos superiores de la meiofauna metazoaria, siendo los nemátodos el grupo dominante, contribuyendo con más de 95% de la abundancia total. La distribución vertical de la abundancia se concentró en las primeras capas del sedimento en la mayoría de los grupos a excepción de Acari y larvas nauplii. El análisis de correspondencia canónico reveló correlaciones significativas (P < 0,05) entre la abundancia de la meiofauna y el contenido orgánico, profundidad y potencial redox de los sedimentos. Estos resultados representan una primera aproximación al conocimiento de la ecología de ensambles de meiofauna de fondos blandos en la Bahía de Valparaíso y pueden ser útiles como línea de base para futuras comparaciones y descripciones de las condiciones ENSO (El Niño Oscilación del Sur) y las variaciones estacionales de estas desconocidas comunidades bentónicas. Palabras clave: meiofauna, nematodos, abundancia, sedimentos, Bahía de Valparaíso, Pacífico suroriental. INTRODUCTION The seafloor benthic assemblages inhabiting the continental shelf off north and central Chile are influen__________________ Corresponding editor: Claudia Bremec ced by several oceanographic features such as oxygen minimum zones (OMZs) (Gallardo et al., 2004; Sellanes et al., 2007, 2010; Fuenzalida et al., 2009, Ulloa & Pantoja, 2009), coastal upwelling (Fossing et 923 2 Latin American Journal of Aquatic Research al., 1995; Gutiérrez et al., 2006) and the ENSO events (Arntz et al., 1991; Neira et al., 2001a, 2001b; Sellanes et al., 2007; Moreno et al., 2008). In this region, a large fraction of the organic matter derived from primary production is accumulated on the sediment, which is characterized by having high remineralization rates (Gutiérrez et al., 2000). These factors may change the biochemical properties of the sediments (Cowie, 2005; Neira et al., 2013) and bottom water column with observable effects on the composition, abundance, diversity and distribution of benthic fauna as has been observed in another regions (Levin, 2003; Gooday et al., 2009, 2010). The meiofauna represents the most abundant metazoan group in the marine benthic system, distributed from the intertidal to abyssal depths, and with productivity rates similar to or higher than those of macrofauna (Gerlach, 1971; Giere, 2009). The meiofauna enhance organic matter biomineralization enhancing the recycling of nutrients and organic carbon making them available for assimilation into new biomass (e.g., Gerlach, 1971; Fenchel, 1978; Giere, 2009; Neira, et al., 2013). In addition, these communities are also food supply for a large number of larger organisms and show sensitivity to anthropogenic impacts, serving as environmental indicators (Boyd et al., 2000). Meiobenthic studies from Chilean waters have been carried out from intertidal (Asencio et al., 1995; Rodríguez et al., 2001; Lee & Riveros, 2012; Valderrama-Aravena et al., 2014), continental shelf (Neira et al., 2001a, 2001b; Sellanes et al., 2003; Sellanes & Neira, 2006; Veit- Köhler et al., 2009; Neira et al., 2013) and hadal trenches environments (Danovaro et al., 2002; Gambi et al., 2003). There are also studies on the use of these organisms as anthropogenic bioindicators (Lee et al., 2006; Lee & Correa, 2007) and their relationships with abiotic parameters from sediments in fjords ecosystems (Chen et al., 1999; George & Schminke, 1999; Stead et al., 2011). Investigations made on the continental shelf have been mostly developed off Concepción, south central Chile (36°40’S). They have focused on describing the composition, structure and function of meiofaunal assemblages in response to ENSO and OMZs conditions as well as their function in the energetic flux of benthic systems (Sellanes et al., 2003; Sellanes & Neira, 2006; Neira et al., 2013). In Valparaíso Bay (33°S), there are limited studies on continental shelf mega- and macrobenthic communities (Andrade, 1986, 1987) and virtually there are no studies about the meiobenthos. Therefore, the current research is the first to investigate the composition and community structure of soft bottom meiofauna assemblages in Valparaíso Bay. The aims were a) to describe the taxonomic composition, density and vertical distribution of the metazoan meiofauna, and b) to characterize environmental factors influencing the meiofauna distribution. MATERIALS AND METHODS Study area Valparaíso Bay (32°9´S, 71°6´W) is located on the continental shelf off central Chile. In this area, oceanographic process such as upwelling, OMZs, ENSO and local organic enrichment associated with sewage outfalls influence sediment conditions and benthic communities (Brandhorst, 1971; Andrade et al., 1986; Sievers & Vega, 2000; Silva & Valdenegro, 2003; Rutllant et al., 2004; Bello & Maturana, 2004). In addition, terrestrial inputs from Aconcagua River contribute to organic enrichment and habitat heterogeneity in coastal zones, and are distributed by complex local hydrographic conditions thus enhancing the species sensitivity levels, which may lead to changes in their geographical distribution limits as has been already documented for other locations (Teixeira et al., 2012). An oceanographic campaign was undertaken in March 2013, considering three stations along a depth transect. The two shallowest stations (3 and 4) are situated on the inner continental shelf at 80 and 100 m depth respectively (Fig. 1). The deepest station (5) is situated on the outer continental shelf at 140 m depth, where hypoxic conditions have been recorded (Fig. 1). Records of the location and depth of each sampling station were made using a GPS Echo-sounder Garmin. Sampling and processing Water column temperature, salinity and dissolved oxygen (DO) were measured using a CTDO Seabird 19 Plus. In addition, discrete water samples at different depths were collected with Niskin bottles for DO. Samples for meiofauna and sediment parameters were collected using a gravity corer with a 50 mm internal diameter. Five sediment samples were collected in each station for organic matter content (OM), grain size, redox potential (EhNHE), chlorophyl-a (Chl-a), phaeopigment (Phaeop), carbon stable isotope ratio (δ13C), total organic carbon (TOC) and carbon-nitrogen ratio (C:N) analyses. From each station two replicates for meiofauna were sub-sampled with Plexiglas tubes 30 mm internal diameter. To study the vertical distribution the first six centimeters of sediment column were examined. In order to achieve these the tubes were processed and subdivided into three horizontal layers (0-2, 2-4 and 4-6 cm). All samples were fixed in 4% formalin buffered with sodium borate. A 63 µm mesh sieve was used and meiofauna were extracted using the Metazoan meiofauna assemblages off central Chile 9243 Figure 1. Study site showing the oceanographic sampling stations. methodology of resuspension-decantation (Wieser, 1960) after sonicating the sediment for 10 s (Thiel et al., 1975). The efficiency of this method has been reported by Murrell & Fleeger (1989). All meiofaunal individuals were sorted, identified into major taxa and counted under a stereo microscope Nikon Eclipse E 200. Abundance was expressed as individuals per 10 cm2. Laboratory analyses The samples for DO were analyzed by the Winkler method as modified from Carpenter’s technique (Knap et al., 1993), and microtitrated with a DOSIMAT. Total organic matter (TOM) in marine sediments was determined at 2 cm intervals by loss of weight on ignition at 475-500ºC for 4 h (Byers et al., 1978). Carbon stable isotope content (δ13C) was analyzed by mass spectrometry (VG Micromass 602C equipment) at the Environment Isotopes Laboratory of the CCHEN (Chile). The δ13C (‰) values are relative to the Pee Dee Belemnite (PDB) Standard (Silva et al., 2011). In order to estimate the contribution of allochthonous organic matter (Alloch) in the study area, we used -26.9‰ as terrestrial reference value, and we used for marine sediment an average value obtained from samples in the study area (-21.7‰), which were consistent with those reported by Silva et al. (2011). The total organic carbon (TOC) and total nitrogen (TN) content of the surface sediments were analyzed on freeze-dried and homogenized sample material. Measurements were made in a CHN elemental analyzer (Flash EA 2000) after acidification treatment with 1 N HCl. Redox potential (EhNHE) was measured at 2 cm intervals in the laboratory using a platinum standard combination electrode with a calomel internal reference (SG™, Mettler Toledo). The total sulfides content in was determined colorimetrically according to method of Cline (1969). Chl-a and phytopigment degradation products (i.e., phaeopigments) were extracted from duplicate subsamples of wet sediment (ca. 1 g) using 90% acetone. After 24 h of darkness at 4°C, the samples were sonicated for 5 min, centrifuged at 3,000 rpm (1,000 g) for 10 min, and extracts were fluorometrically analyzed for Chl-a and Phaeop content. Chla and Phaeop values were obtained before and after acidification with 1 N HCl, respectively, according to Lorenzen’s method, as described in Parsons et al. (1984), where the volume of water is substituted by the dry weight (DW) of the sediment expressed in gram. Values were thus expressed, corrected for porosity as measured by the water content, as µg Chl-a g-1 DW. This was obtained after drying duplicate sediment subsamples (ca. 1 g) at 105°C for 20 h. Chloroplast pigment equivalents (CPE) is the sum of Chl-a and Phaeop, which is an indicator of fresh organic matter 4925 Latin American Journal of Aquatic Research (Pfannkuche & Soltwedel, 1998). Particle grain size data were analyzed following Folk and Ward scale (Folk, 1980; Blott & Pye, 2001). Data analyses Kruskal-Wallis test were used to detect differences in meiofauna mean abundance between sites. The correlations between biological and sediment variables were calculated using Spearman correlation analyses. All tests were performed using the Statistica software package version 7.0. In addition, Canonical correspondence analysis (CCA) was performed with the software PAST 3.01 (Hammer et al., 2001). CCA was applied to relate the set of environmental parameters and meiofaunal groups among sampling stations, as suggested by Jongman et al. (1987). RESULTS Sediment properties Details of environmental parameters are shown in Table 1. Bottom water DO concentrations showed a decreasing pattern with depth with a mean of 2.42 ± 0.29 mL L-1. Similar spatial trends were observed for Chl-a, Alloch and δ13C variables with mean values of 10.9 ± 1.35 µg g-1, 41.03 ± 22.95 (%) and -23.83 ± 1.19 ‰, respectively. The opposite pattern was observed for organic matter content (%) with a higher proportion at station 5 in the 0-2 and 2-4 cm sediment layers. The same situation was recorded for EhNHE (mV) with the highest values recorded in the 2-4 and 4-6 cm sediment layers. The values observed for these parameters indicate the low oxidation of sediments at the study site. The rest of sediment variables showed spatial variability without a clear pattern with mean values of 15.23 ± 4.44 mg g-1 for TOC, 12.21 ± 1.11 molar for C:N, 22.97 ± 8.28 µg g-1 for Phaeop, and 33.88 ± 9.41 µg g-1 for CPE. The sediment composition (e.g., grain size) was characterized by a higher proportion of mud (>70%) and lower content of sand (<28%) in all stations. However, the sediment parameters did not exhibit significant differences among stations in the study area (Kruskal-Wallis test P > 0.05). Taxonomic composition and abundance A total of 40 taxa (different morphotypes) were recognized in the study site belonging to nine upper metazoan meiofaunal groups. Nematodes were the dominant group contributing with more than 95% of relative abundance at all sites (Table 2). In this group 22 taxa were distinguished belonging to 14 familias. Copepoda and Acari with 6 and 9 taxa respectively were the next most important groups, but they did not exceed 3 and 6% of total relative abundance, respectively. The rest of taxa: nauplii larvae, gastrotrichs, kinorhynchs, polychaetes, oligochaetes and cumaceans exhibited low relative abundances (below 1%) and scarce taxonomic representation. The main taxonomic groups are show in Fig. 2. Details of taxonomic composition and hits relative abundance are show in Annex 1. Meiofaunal abundance decreased with the depth ranging from 2,218 ± 643 ind 10 cm-2 at stn. 3 to 1,592 ± 148 ind 10 cm-2 at stn. 4. No significant differences were observed between stations (Kruskal-Wallis test, H2 = 1.21, P > 0.05). Nematode abundances reached maximum values at station 3 with 2,136 ± 634 ind 10 cm-2, while the lowest abundances were recorded at stn. 4 with 1,528 ± 138 ind 10 cm-2 (Fig. 3a). Acari abundances were two to three orders of magnitude lower than nematodes, and were the second most abundant meiofaunal group, which ranged from 56 ± 9 ind 10 cm-2 at stn. 3 to 7 ± 2 ind 10 cm-2 at station 5 (Fig. 3b). Copepod abundances varied from 10 ind 10 cm-2 at stn. 4 and 5, to 5 ± 0.98 ind 10 cm-2 at stn. 3. The rest of taxa recorded abundances lower than 2 ind 10 cm-2. Nematodes, nauplii larvae, copepods, acari and gastrotrichs were recorded at all stations. Contrasting, kinorhynchs were recorded at stn. 4 and 5, with higher abundances at the stn. 5 (27 ± 6 ind 10 cm-2). Cumaceans and oligochaetes were also recorded at station 4, while polychaetes only at stn. 5. These taxa always were recorded with very low abundances (<1 ind 10 cm-2). Vertical distribution Vertical distribution profiles of the major meiofaunal taxa are shown in Figure 4. The meiofauna vertical distribution varied in the three stations. Meiofaunal abundances decreased with the sediment depth and nematodes were the dominant group at each depth (>90% of abundance) dictating the overall vertical distribution pattern for the whole community. The single exception to this trend was Acari. This group increased with sediment depth recording the highest density in the 4-6 cm layer with a mean of 19.3 ± 14,9 ind 10 cm-2. On the other hand, nauplii larvae recorded a density slightly lower at 4-6 cm layer (3.79 ± 4.13 ind 10 cm-2) in comparison to 0-2 cm layer (3.83 ± 4.37 ind 10 cm-2). The great majority of the taxa were concentrated in the 0-2 cm sediment layer. Even some groups such as kinorhynchs, cumaceans and polychaetes were not recorded in the lower layers, while copepods and gastrotrichs had a wider vertical distribution. Including all sites and sediment layers, the median proportion of specimens (relative abundance) recorded in the 0-2, 2-4 and 4-6 cm layers was 75.2%, 9265 Metazoan meiofauna assemblages off central Chile Table 1. Abiotic properties of three sampling stations off central Chile. Sedimentary parameters are given for the top 0-1 cm layer (means of 3 samples). TOC: total organic carbon; C:N: carbon-nitrogen ratio; Chl-a: chlorophyll-a; Phaeop: phaeopigments; Eh: redox potential; TOM: total organic matter; δ13C: ratio of stable isotopes; CPE: chloroplast pigment equivalents; Alloch: allochthonous organic matter. Station 3 80 32°54'31 71°35'44 11.31 2.73 12.41 12.79 12.28 32.44 44.73 Depth (m) Latitude Longitude Bottom water temperature (°C) Bottom water oxygen (mL L-1) TOC (mg g-1) C:N ratio (molar) Chla (µg g-1) Phaeop (µg g-1) CPE (µg g-1) EhNHE (mV) 0-2 cm 2-4 cm 4-6 cm Sulfides (mg kg-1) Mud (%) Sand (%) TOM (%) 0-2 cm 2-4 cm 4-6 cm δ13C (‰) Alloch (%) Station 4 100 32°54'31 71°36'48 11.26 2.37 20.35 12.91 10.84 17.06 27.91 Station 5 140 32°54'31 71°38'57 11.2 2.16 12.95 10.93 9.59 19.42 29.01 56 -26 -68 15 84.4 15.6 27 -32 -76 17.2 72 28 33 -44 -107 1.15 93.6 6.3 6.1 6.5 6.4 -24.8 59.62 7.6 7.7 6.8 -24.2 48.08 7.7 8.4 6.5 -22.5 15.38 Table 2. Relative abundance (%) of meiofaunal groups in the study area in different sediment layers (0-2, 2-4 and 4-6 cm). Nem: Nematoda, Cop: Copepoda, Nau: Nauplii, Pol: Polychaeta, Aca: Acari, Cum: Cumacea, Gas: Gastrotricha, Olig: Oligochaeta, Kin: Kinorhyncha Station 3 0-2 cm 2-4 cm 4-6 cm Total 4 0-2 cm 2-4 cm 4-6 cm Total 5 0-2 cm 2-4 cm 4-6 cm Total Nem Cop Nau Pol Aca Cum Gas Olig Kin 98.3 97.2 82.4 96.3 0.25 0.60 0.23 0.20 0.13 3.57 0.55 - 0.65 2.70 13.40 2.54 - 0.55 0.35 - - 97.6 95.9 72.4 95.9 0.78 0.63 0.66 1.60 0.63 - 0.11 4.10 25.20 2.10 0.06 0.04 0.17 0.13 0.79 0.04 0.61 0.49 97.1 97.2 90.5 97 0.64 0.31 0.57 0.31 3.17 0.12 0.05 0.04 1.80 6.40 0.41 - 0.29 0.31 0.29 - 1.90 1.60 18% and 6.8% respectively for the total meiofauna. Nevertheless, without considering the nematode abundances this proportion changed between stations. At stn. 3 the higher proportion of specimens, 51.8%, was concentrated at 4-6 cm sediment layer. At stn. 4 specimens were slightly more abundant at 0-2 cm 6927 Latin American Journal of Aquatic Research Figure 2. Light microscope photographs of meiofaunal taxa found at Valparaiso Bay. a) Nematoda, b) Copepoda, c) Nauplii, d) Gastrotricha, e) Kinorhyncha, f) Oligochaeta, g) Polychaeta, h) Cumacea, i) Acari. Figure 3. Meiofauna mean abundance in each sampling station. a) Nematoda, b) Copepoda, c) Acari, and d) Total meiofauna. Error bars indicate the standard deviation. Metazoan meiofauna assemblages off central Chile 9287 Figure 4. Mean abundance vertical distribution at 0-2, 2-4 and 4-6 cm sediment layers. a) Nematoda (all stations), b) Station 3, c) Station 4, and d) Station 5. Graphs b, c and d: nematodes excluded. (47.7%), while that at stn. 5 the distribution was closer to the overall pattern (nematodes included) with 79.4% at 0-2 cm sediment layer. Relationships between environmental parameters and meiofauna The results of the CCA are shown in Fig. 5. Only the five environmental variables that explained most of the variance were included in the analysis (i.e., Depth, C/N, Allochthonous OM, TOC and Redox potential). When the abundance of the dominant meiofaunal groups is related to the environmental variables the first CCA axis eigenvalues accounted for 89.8% of the total variance and the second CCA axis eigenvalues accounted for 10.3% of the explained variance. This suggests a relatively good dispersal of the biological data along the different axis in both analyses. For the meiofauna composition, the first axis reveals gradients influenced by allochthonous content of organic matter (r = 0.99), C/N ratio (r = 0.96) and depth (r = -0.85), while the second axis reflects a gradient influenced by TOC (r = 0.97) and redox potential (r = -0.84). In terms of meiofauna composition, Nematoda was the dominant group in all stations, but Cumacea and Oligochaeta were more representatives in stn. 4, while Polychaeta and Kinorhyncha in stn. 5. DISCUSSION Environmental parameters Meiofaunal assemblages at central Chile are influenced by the Equatorial Subsurface Water (ESSW), which flows poleward over the shelf and upper slope (Sellanes & Neira, 2006). This water mass has low oxygen concentrations and is the source of coastal upwelling that drives high primary production (Fossing et al., 1995; Daneri et al., 2000) and generates the food supply to the seabed (Gutiérrez et al., 2000). The C/N ratio value recorded in this study was 10.93 on the outer continental shelf. This value indicates that accumulated organic matter has been decomposed from nitrogen compounds (Scheffer & Schachtschabel, 1984). C/N ratio values in the first few centimeters of sediment were similar to values found off Peru with 9.8 (Levin et al., 2002) and higher in comparison to values recorded in Concepción Bay by Veit-Köhler et al. (2009) and Neira et al. (2013) with 7.8 and 7.06, respectively. TOC contents in the study area were similar to those recorded by Neira et al. (2013) off Concepción at 122 m depth with 46.91 mg g-1. In comparison with other upwelling areas, TOC values were also similar to those reported at the Arabian Sea (14.3-54.3 mg g-1) (Smallwood & Wolff, 2000), but lower that those recorded off Peru 8929 Latin American Journal of Aquatic Research Figure 5. Canonical correspondence analysis displaying the meiofaunal groups in relation to environmental variables that best explain the abundance distribution among stations. Relationships were significant (P < 0.05). (>205 mg g-1) (Neira et al., 2001b). The concentrations of Chl-a and Phaeop in the current research were lower than found in studies made by Neira et al. (2013) (124.62 and 196.76 µg g-1, respectively). However, they were higher than those recorded by Neira et al. (2001b) (4.30 µg g-1) on the continental slope off Peru. Meiofauna It is known that habitat heterogeneity due to physical or chemical properties of the sediment would be an important factor controlling the meiobenthos community structure (Gooday et al., 2010). In physical terms the grain size variations recorded were not important as correlations with meiofaunal groups were not found. However in chemical terms in addition to the DO, content of organic matter, Chl-a and CPE decreased with depth and significant correlations were found between meiofauna abundance and organic content (C/N, Allochthonous organic matter and TOC), depth and redox potential sediment parameters. For instances, the organic matter content, Chl-a and DO were positively correlated with meiofauna abundance in Concepción Bay (Neira et al., 2013; Sellanes et al., 2003; Sellanes & Neira, 2006; Veit-Köhler et al., 2009). In our study area, nematodes constitute more than 95% of total meiofauna abundances, being considered the taxon that can best cope with low oxygen conditions and high organic matter content on the sediments. In fact, only meiofauna is well adaptated to low oxygen in the suboxic to anoxic layers (Braeckman et al., 2013). In this sense the deeper vertical distribution of Acari and nauplii larvae in some sedimentos layers, where negative values of redox potential were recorded, would demonstrate this kind adaptation in the current study. Table 3 shows the meiofaunal abundance from different locations with similar characteristics to Valparaíso Bay. The total abundances of nematodes at the three stations were slightly higher than those reported by Sellanes et al. (2003) and Veit-Köhler et al. (2009) for the continental shelf off central Chile. Mean abundances recorded on the inner and outer continental shelf in the current study (Fig. 3d) were similar to those described by De Bovée et al. (1996), where meiofaunal 9309 Metazoan meiofauna assemblages off central Chile Table 3. Comparison of meiofaunal abundances among areas sharing similar characteristics with Valparaíso Bay and/or adjacent continental shelf. Abundances reported as ind 10 cm -2. Zone Arabian Sea Southeast continental shelf of India Continental shelf Perú (12°S) Atacama Trench Continental shelf central Chile Continental shelf central Chile Continental shelf, Valparaiso Bay Depth (m) 400 75-100 100-150 305 1.050 7.800 88 120 126 80 100 140 Environment Upwelling Upwelling OMZ Bathyal depths Hadal depths OMZ OMZ OMZ Seasonal hypoxia Seasonal hypoxia Seasonal hypoxia densities ranged between 1.000 and 2.000 ind 10 cm-2 from subtidal muddy environments. It is important to note that the study area is influenced by a seasonal hypoxia with DO concentrations about 2.34 mL L-1, while low oxygen levels (<0.5 mL L-1) have been documented at Concepción bay. Indeed, low oxygen levels have been registered on the continental shelf off Peru (Neira et al., 2001b) and in the Arabian Sea (Cook et al., 2000), where nematodes abundance appear to be similar to our study. On the other hand, the number of taxonomic groups found in this study (9 taxa) was lower than observed for Concepción Bay by Sellanes et al. (2003) with 13 taxa and for Chiloé, southern Chile by Veit-Köhler et al. (2009) where 16 taxa were recorded. This minor presence of taxonomic groups could be explained by nematode dominance (total abundance >95%) (Table 2) or due to minor number of samples considered. Levin et al. (1991) and Neira et al. (2001b) argue that these organisms are highly successful in sediments rich on organic matter and with low dissolved oxygen concentrations. In this respect the organic matter content averaged 7.13% in surficial sediments (0-2 cm) while hypoxic conditions were recorded (Table 2). These authors affirm that the oxygen could control the meiofauna composition at level of major taxonomic groups within the OMZ zones. Meiofauna vertical distribution is mainly controlled by food deficiency and oxygen availability with around 90% of total meiofauna being concentrated between 05 cm sediment layers (Giere, 2009). In our study, 93% of total meiofauna was concentrated in the 0-4 cm sediment layer (Fig. 4a) which could be an adaptive response related to their trophic strategies. However our results suggest that this vertical distribution pattern would be mainly determined by higher concentrations Nematode abundance 1.700 1.502 ± 430 498 ± 157 5.072 ± 2.344 1.193 - 2.417 738 - 1.268 1.555 - 3.077 2.136 ± 633 1.528 ±138 1.687 ± 69 Total meiofauna 700 800 1.517 ± 431 550 ± 186 6.378 ± 3,061 1.202 - 2.433 895 - 1.318 1.577 - 3.229 2.218 ± 643 1.592 ± 148 1.739 ± 82 Reference Cook et al. (2000) Ansari et al. (2012) Neira et al. (2001b) Danovaro et al. (2002) Sellanes et al. (2003) Veit-Köhler et al. (2009) This study of fresh organic content in the surficial sediment layers. It is well know that nematodes have a wide variety of trophic strategies from carnivore predators to bacterivorous guilds (Wieser, 1960; Neira et al., 2013) and they are dominants in all type of sediments inhabiting in both oxidized and reduced conditions. However a trophic guild classification was not made for this study, although some similar trophic strategies to those reported by Neira et al. (2013) for Concepción could be found. In addition, nematodes dominance is thought to be the result of the capacity to tolerate low oxygen conditions and the reduced predation pressure/competition as a result of the higher sensitivity of other benthic organisms to hypoxia/anoxia (Neira et al., 2001a, 2001b; Levin et al., 2002). The results recorded in the current study showed that the vertical distribution of nematode abundances changed mainly between 2-4 and 4-6 cm sediment layers (Table 2). This minor relative abundance that was clearly observed at station 4, where a higher proportion of sand was recorded, could be explained by the higher relative abundance of Acari and nauplii at 4-6 cm layer. This could be suggesting a nematode response to competition with other taxa or sensitivity to redox potential conditions of the sediments as revealed by CCA. Gastrotrichs, kinorhynchs and copepods concentrated their abundances in the first centimeters of the sediment. The vertical distribution in these groups could be explained by their sensitivity to low levels of DO, their morphology and body size (Giere, 2009). In the case of copepods they could be unable to easily adapt to interstitial environments. A different vertical distribution pattern was observed for nauplii and Acari. Nauplii did not show a higher abundance in surficial sediment layers, with wide vertical variation between 931 10 Latin American Journal of Aquatic Research stations. Contrastingly, Acari were mainly distributed in sub-surficial sediment layers (2-4 and 4-6 cm) at all stations. Vertical distribution pattern for nauplii and Acari could be associated to predation pressure and bioturbation in surficial sediment where the competition for habitat and fresh food supply is very high. For instances, a similar vertical distribution pattern also have been recorded for Acari (Acarina) in seamounts (Zeppilli et al., 2013). It is known that oceanographic characteristics along the continental margin off central Chile are influencing the spatial distribution of mega-, macro- and meiobenthic communities (e.g., Palma et al., 2005; Quiroga et al., 2009; Sellanes & Neira, 2006). In fact, the effects of upwelling under normal, ENSO and OMZs conditions have been well documented off central Chile (Neira et al., 2013; Sellanes et al., 2003; Sellanes & Neira, 2006), the continental shelf off Peru (Neira et al., 2001b; Levin et al., 2002) and in the Arabian sea (Cook et al., 2000; Gooday et al., 2000). From these studies, the organic matter quality and oxygen availability have been the main variables explaining the meiofauna community structure. In the current study the organic content of the sediments comes from primary production together to redox potential and depth were the only environmental variables explaining the distribution of meiofauna groups, while oxygen levels were not correlated. The composition, abundance and distribution of the meiobenthic community provided in this study represents a non-ENSO condition and can be useful as a baseline for future descriptions of this relevant oceanographic phenomena, which has already been confirmed for the South Pacific Ocean by 2015 (National Wheather Service, 2014). Time series studies are suggested to assess the ecological response of these assemblages to conditions before mentioned and to another such as OMZ and upwelling seasonal changes. ACKNOWLEDGEMENTS Authors wish thank to Francisco Gallardo for his field work assistance. Williams Caballero thanks to Meioscool International Workshop 2013 organization and Universidad of Valparaíso for the financial support to attend to Meioscool International Workshop held in Brest, France. Authors also thank to Benjamin Ganga for the statistical analyses support and Carlos Neira (Scripps, UCSD) for his comments and assistance for improving this manuscript. 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Cattaneo, R. Danovaro & R.S. Santos. 2013. Meiofauna assemblages of the Condor Seamount (North-East Atlantic Ocean) and adjacent deep-sea sediments. Deep-Sea Res. II, 98: 87100. Received: 9 January 2015; Accepted: 7 September 2015 Annex 1. Meiofaunal community composition and its relative abundance (%) in the study site. Nematoda Axonolaimidae sp.1 Odontophora sp. Cyatholaimidae sp.1 Cyatholaimidae sp.2 Enoplidae Ironidae Oncholaimidae Selachinematidae Ceramonematidae Ceramonema sp. Pselionema sp. Desmoscolecidae sp.1 Desmoscolecidae sp.2 Desmoscolex sp. Oxystominidae cf Halalaimus sp. Diplopeltidae sp.1 Campylaimus sp. Comesomatidae sp.1 Sabatieria sp. Chromadoridae sp.1 Neochromadora sp. Microlaimidae Thoracostromopsidae Acari (Halacarids) Acari sp.1 Acari sp.2 Acari sp.3 Acari sp.4 Acari sp.5 Acari sp.6 Acari sp.7 Station 3 Station 4 Station 5 12 14 7 13 3 6 1 15 4 6 3 5 17 8 13 6 4 2 11 13 5 13 11 24 13 13 8 7 4 9 3 2 7 8 5 5 32 23 21 16 8 34 14 18 5 12 7 12 7 29 7 20 6 935 14 Latin American Journal of Aquatic Research Continuation Station 3 Acari sp.8 Acari sp.9 Copepoda (Harpacticoidea) Copepoda sp.1 54 Copepoda sp.2 39 Copepoda sp.3 7 Copepoda sp.4 Copepoda sp.5 Copepoda sp.6 Nauplii larvae Nauplii sp.1 47 Nauplii sp.2 36 Nauplii sp.3 17 Nauplii sp.4 Nauplii sp.5 Cumacea Dyastilidae sp.1 Polychaeta Paraonidae sp.1 Gastrotricha Gastrotricha sp.1 75 Gastrotricha sp.2 25 Gastrotricha sp.3 Kinorhyncha Kinorhyncha sp.1 Kinorhyncha sp.2 Oligochaeta Oligochaeta sp.1 Station 4 10 46 17 25 12 Station 5 14 5 12 38 34 16 40 29 12 19 29 23 8 24 16 100 100 60 20 10 100 100 100 60 40 Lat. Am. J. Aquat. Res., 43(5): 936-943, 2015 DOI: 10.3856/vol43-issue5-fulltext-13 Seasonal infestation of Excorallana berbicensis 9361 Research Article First study on infestation of Excorallana berbicensis (Isopoda: Corallanidae) on six fishes in a reservoir in Brazilian Amazon during dry and rainy seasons Huann Carllo Gentil-Vasconcelos1 & Marcos Tavares-Dias1,2 1 Postgraduate Program on Tropical Biodiversity (PPGBIO) Federal University of Amapá Macapá, AP, Brazil 2 Aquatic Organism Health Laboratory, Embrapa Amapá, Rodovia Juscelino Kubitschek N°2600, 68903-419, Macapá, AP, Brazil Corresponding Author: Marcos Tavares Dias ([email protected]) ABSTRACT. We analyzed the infestation levels of Excorallana berbicensis on Acestrorhynchus falcirostris, Ageneiosus ucayalensis, Geophagus proximus, Hemiodus unimaculatus, Psectrogaster falcata and Serrasalmus gibbus in a reservoir in the Araguari River basin, northern Brazil, during the dry and rainy seasons. For P. falcata, the infestation levels due to E. berbicensis were greater during the rainy season. For all the species studied, the peak parasite prevalence was in the month of highest rainfall levels and there were two peaks of parasite abundance: one in the month with highest rainfall level and the other in the month of transition from the rainy season to the dry season. In these hosts, around 70% of the E. berbicensis specimens were collected during the rainy season. The body conditions of the hosts also did not suffer any seasonal influence. Despite the differences in seasonal rainfall levels, there was no fluctuation in transparency, turbidity, pH, electric conductivity, temperature and dissolved oxygen levels in the water, due to the stability of these parameters during the seasonal cycle investigated in this artificial Amazon ecosystem. This was the first report on the seasonality of infestation by E. berbicensis associated with fish. Keywords: Excorallana berbicensis, isopod, ectoparasites, wild fish, seasonality, Amazon River. Primer estudio de la infestación de Excorallana berbicensis (Isopoda: Corallanidae) en seis peces en un embalse del Amazonas brasileño durante las estaciones seca y lluviosa RESUMEN. Se analizó los efectos de las estaciones seca y lluviosa sobre los niveles de infestación de Excorallana berbicensis en Acestrorhynchus falcirostris, Ageneiosus ucayalensis, Geophagus proximus, Hemiodus unimaculatus, Psectrogaster falcata y Serrasalmus gibbus en un embalse en la cuenca del Río Araguari, norte de Brasil. Para P. falcata, la prevalencia y abundancia de E. berbicensis fue mayor en la estación lluviosa. Para todas las especies estudiadas, la prevalencia máxima del parásito fue en el mes más lluvioso, donde hubo máximos de abundancia de parásitos: una en el mes con mayores precipitaciones y la otra en el mes de transición de la estación lluviosa a seca. En estos hospederos, se obtuvo alrededor del 70% de muestras de E. berbicensis durante la estación lluviosa. Las condiciones del cuerpo de los hospederos tampoco sufrieron influencia estacional. A pesar de las diferencias en los niveles estacionales de precipitaciones, no hubo fluctuaciones en transparencia, turbidez, pH, conductividad eléctrica, temperatura y oxígeno disuelto en el agua, debido a la estabilidad de estos parámetros durante el ciclo estacional analizado en este ecosistema artificial Amazónico. Este es el primer registro sobre la estacionalidad de la infestación de E. berbicensis asociado a peces. Palabras clave: Excorallana berbicensis, isópodos, ectoparásitos, peces salvajes, estacionalidad, Amazónia. __________________ Corresponding editor: Mauricio Laterça 2937 Latin American Journal of Aquatic Research INTRODUCTION Excorallana Stebbing, 1904 (Corallanidae) are isopods consisting of 24 species (Schotte, 2014) occurring predominantly in marine environments of tropical and subtropical latitudes (Guzmán et al., 1988; Delaney 1989). They are associated especially with substrates (Delaney, 1984; Hendrickx & Espinosa-Pérez, 1998; Morgado & Tanaka, 2001). Corallanids of this genus have also been occasionally described associated to zooplankton (Guzmán et al., 1988), also collected from the intertidal zone (Kensley et al., 1995) and to marine fish species from different environments (Williams Jr. & Bunkley-Williams, 1994; Semmens et al., 2006; Álvarez-León, 2009). Some species of Excorallana occur especially in environments of great depth (Delaney, 1989), but only Excorallana berbicensis Boone, 1918, E. tricornis occidentalis Richardson, 1905, E. quadricornis Hansen, 1890 and E. longicornis Lemos de Castro, 1960 have been collected from mangroves (Delaney, 1984). Corallanids are voracious carnivore isopods that act as predators and also as scavengers (Brusca & Wehrtmann, 2009). E. tricornis occidentalis is a facultative parasite for many marine fish and, when in massive infestations, it causes serious damage to fishing of Epinephelus striatus Bloch, 1792 (Semmens et al., 2006). However, information on Excorallana spp. on freshwater fish is scarce (Van Name, 1925; Monod, 1969; Thatcher, 1995). Excorallana spp. has mostly been studied regarding their taxonomy (Van Name, 1925; Monod, 1969; Delaney, 1984, 1989; Kensley et al., 1995; Thatcher, 1995; Hendrickx & Espinosa-Pérez, 1998), but a few studies on their epidemiology in fish have been conducted (Semmens et al., 2006). Excorallana berbicensis was described parasitizing Lycengraulis grossideus Spix & Agassiz, 1829 in rivers from French Guiana (Van Name, 1925); a species of shark in freshwater from Guyana (Monod, 1969); and Ageneiosus inermis Linnaeus, 1766 from Amazon River basin, in Brazil (Thatcher, 1995). However, in addition to the small number of studies on E. berbicensis in association with fish, there are no reports regarding seasonal variation in infestation levels of these isopods in host fish population. In the Amazon region, seasonality influenced by precipitation is characterized by two cycles, the rainy and dry season (Souza & Cunha, 2010; Cunha et al., 2013). These seasonal dynamics greatly influence in ichthyofauna community structures (Galacatos et al., 2004) and can also influence infracommunities of parasites in fish populations. For different fish species from Amazon, low levels of infestation by argulids species have been reported in the dry season (Malta, 1982; Malta & Varella, 1983). In contrast, parasitism by Dolops nana (Neves et al., 2013), Miracetyma sp. (Vital et al., 2011) and Ergasilus turucuyus Malta & Varella, 1996 (Vasconcelos & Tavares-Dias, 2014) have not been found to be influenced by the dry season or rainy season. However, Bauer & Karimov (1990) argued that, in regions between the tropics, the relatively constant climate does not favor seasonal fluctuations of parasitism. In temperate climatic regions, temperature has been considered to be the most important factor influencing the seasonality of parasite infracommunities. Consequently, it can directly or indirectly influence ectoparasites crustacean infestations (Jones, 1974; Guzmán et al., 1988; Kadlec et al., 2003; Pech et al., 2010; Alsarakibi et al., 2014). In the Reservoir of the Coaracy Nunes hydroelectric power plant in Araguari River basin, in the eastern Amazon region (Northern Brazil), Ageneiosus ucayalensis Castelnau, 1855; Hemiodus unimaculatus Bloch, 1794; Serrasalmus gibbus Castelnau, 1855; Geophagus proximus Castelnau, 1855, Acestrorhynchus falcirostris Cuvier, 1819 and Psectrogaster falcata Eigenmann and Eigenmann, 1889 are the most abundant fish species (Sá-Oliveira et al., 2013, 2015). These six fish species presents different life habits, once H. unimaculatus has omnivorous diet, mainly consuming algae, detritus and other aquatic invertebrates, and P. falcata is detritivorous, feeding on detritus and microorganisms associated with the substrate. Geophagus proximus is omnivorous, mainly feeding of plant material, mollusks, insects and other aquatic invertebrates, and A. ucayalensis is carnivorous, consuming fish, insects and other aquatic invertebrates. Acestrorhynchus falcirostris and S. gibbus are piscivorous fish (Santos et al., 2004). However, the parasites fauna on fish of this reservoir is few known (Vasconcelos & Tavares-Dias, 2014). Thus, the aim of study was to investigate the prevalence and abundance of E. berbicensis in these six species of fish from this Amazonian reservoir during rainy and dry seasons. MATERIALS AND METHODS Study area The water Reservoir of the Coaracy Nunes Hydroelectric Power Plant (Fig. 1) is located in the municipality of Ferreira Gomes, Amapá State, in the eastern Amazon region (northern Brazil). Its area is 23.5 km2, capacity 138 Hm3 and average depth 15 m. This reservoir began its operations in 1974 and is connected to the Araguari River basin, which originates south of the Lombada and Tumucumaque mountain ranges and flows to the Atlantic Ocean (Bárbara et al., 2010; Sá-Oliveira et al., 2013). This reservoir is a tran- Seasonal infestation of Excorallana berbicensis 9383 Figure 1. Fish collection locality, in a reservoir from Araguari River basin, in the eastern Amazon region (Brazil). sition area between lotic and lentic environments and has marginal areas with only a few aquatic macrophytes, especially Eichhornia crassipes and Eleocharis sp., and great quantities of decomposing arboreal vegetation, due to non-deforestation of the area that was destined for the reservoir. Fish and collection procedures For study of parasites, specimens of Acestrorhynchus falcirostris (Acestrorhynchidae), Ageneiosus ucayalensis (Auchenipteridae), Geophagus proximus (Cichlidae), Hemiodus unimaculatus (Hemiodontidae), Serrasalmus gibbus (Serrasalmidae) and Psectrogaster falcata (Curimatidae) were collected in the Coaracy Nunes Reservoir (Fig. 1), a long-established ecosystem, about 40 years (Sá-Oliveira et al., 2015). A total of 296 fish specimens were caught during the dry season (October 2012 to February 2013) and rainy season (April to August 2013) at six sampling points, located at a distance of 889 ± 498 m (range: 544-1777 m) from each other (Fig. 1), for analysis on the seasonal level of E. berbicensis infestation. A total of 65 P. falcata, 63 A. ucayalensis, 62 A. falcirostris, 56 H. unimaculatus, 36 S. gibbus and 14 G. proximus were examined. The fish were caught using simple gill nets (20, 30, 40, 50 and 60 mm mesh), grouped into lengths of 100 m. These nets were installed near the reservoir margins and were left in the water for 12 h, with inspection every two hours. This study was developed in accordance with the principles adopted by the Brazilian College of Animal Experimentation (COBEA). Collection procedures and analysis of parasites After the fish had been removed from the nets, the mouth, integument and fins of each fish were immediately examined for the presence of crustacean parasites. The gills were collected and fixed in 5% formalin, and then were examined with the aid of a stereomicroscope to collect and count the parasites. The crustacean species were conserved in 70% glycerinated alcohol and were prepared for identification, following the recommendations of Eiras et al. (2006). The ecological descriptors used followed the recommendations of Bush et al. (1997). Differences in the prevalence of E. berbicensis between the rainy and dry seasons, as well as between months were evaluated using the chi-square test (2) with the Yates correction. Differences in the abundance of E. berbicensis between rainy and dry seasons were evaluated using the MannWhitney (U) test, and between months using KruskalWallis test (H). The Shapiro-Wilk test was used to determine whether the parasite abundance presented 4939 Latin American Journal of Aquatic Research normal distribution. Each fish was measured for body weight (g) and length (cm), which were used to determine the relative condition factor of the hosts/Kn (Le-Cren, 1951). The Kn of the overall hosts was compared with the Kn of the hosts during dry and rainy seasons, using the Kruskal-Wallis test (Zar, 2010). Water temperature, electric conductivity and dissolved oxygen in water were obtained by means of the YSI 85 multiparameter measuring device, and pH by means of the YSI 60 pHmeter. Turbidity was determined using the obtained by means of the Plus II microprocessing turbidimeter. Transparency was measured using Secchi’s disc. Rainfall levels were obtained through the National Environmental Data System (SINDA-INPE), from the Coaracy Nunes dam hydrometeorological station. RESULTS The body parameters and number of the examined fish by seasons are showed in Table 1. The physical and chemical parameters, with the exception of rainfall levels, were similar during the dry and rainy seasons (Table 2). Excorallana berbicensis infestations occurred on the mouth, gills and integument of the hosts, except for S. gibbus, which only had infestation on its integument. Differences in the prevalence and abundance of this corallanid only occurred in P. falcata, which were greater during the rainy season (Table 3). In G. proximus, infestations occurred only during the rainy season, but the number of hosts examined was low. In A. ucayalensis, A. falcirostris, H. unimaculatus, S. gibbus, G. proximus and P. falcata, there was seasonal fluctuation of E. berbicensis, with highest prevalence in April and highest abundance in April and August (Fig. 2). Considering all the hosts examined, 262 specimens of E. berbicensis were collected during the dry season and 600 during the rainy season. The Kn of the hosts parasitized by E. berbicensis did not differ between the grouped hosts (overall), or between the rainy season and dry season (Table 4). In addition, for A. falcirostris (t = -0.014; P = 0.989), A. ucayalensis (t = -0.058; P = 0.954), H. unimaculatus (t = 0.006; P = 0.995), P. falcata (t = -0.005; P = 0.996) and S. gibbus (t = -0.155; P = 0.877), the grouped Kn also did not differ from the standard (Kn = 1), thus indicating that the hosts presented good body condition. DISCUSSION In P. falcata, the levels of infestation by E. berbicensis were greater during the rainy season. Similar seasonal patterns were reported for abundance of infestations by Dolops discoidalis Bouvier, 1899, D. bidentata Bouvier, 1899 (Malta, 1982), D. striata Bouvier, 1899 and D. carvalhoi Lemos de Castro, 1949 (Malta & Varella, 1983), in different fish of the Amazon region. Pech et al. (2010) also reported that seasonal fluctuation in rainfall levels influenced the levels of infestation by Argulus sp. and Ergasilus sp. in Cichlasoma urophthalmus Günther, 1862 from Yucatan Peninsula (Mexico). In the Amazon region, the environmental conditions during the rainy season are favorable for reproduction of some ectoparasite species, thus providing opportunities for encountering infectious forms with their hosts and contributing towards completing their life cycle (Vital et al., 2011). However, in piranha Pygocentrus nattereri Kner, 1858, Serrasalmus spilopleura Kner, 1858 and S. marginatus Valenciennes, 1837 from Pantanal of Mato Grosso (Brazil), infestation by D. carvalhoi, Argulus elongatus Heller, 1857 and Argulus juparanaensis Lemos de Castro, 1950 was greater during the dry season (Carvalho et al., 2003). Seasonal dynamics influence the environmental quality of different natural ecosystems such as the Araguari River basin, which has pH and dissolved oxygen levels that are lower during the dry season in the Amazon basin (Bárbara et al., 2010). During the period of the present study, the water level in the reservoir of the Coaracy Nunes hydroelectric power plant was relatively constant during the entire year, as also were the water temperature, electric conductivity, dissolved oxygen, pH, turbidity and transparency, which were similar during the rainy and dry seasons. Thus, these factors did not influence the levels of infestation by E. berbicensis in A. falcirostris, A. ucayalensis, H. unimaculatus, G. proximus and S. gibbus. However, Alsarakibi et al. (2014) reported that the occurrence of A. japonicus Thiele, 1900 was strongly influenced by pH, temperature, biochemical oxygen demand, ammonia and dissolved oxygen levels in the water. In river reservoirs, such as the one of the present study, the reduction in water speed contributed towards decreasing the turbidity, which consequently could increase the population of parasite crustaceans, in comparison with the river itself (Morley, 2007). Carvalho et al. (2003) suggested that the behavior of S. marginatus favored greater levels of infestation by ectoparasite crustaceans in environments with higher turbidity. Water turbidity also negatively affects ectoparasite crustaceans, because particulate material in suspension can cause damage to filtration and to delicate feeding organs in planktonic stages (Morley, 2007). Therefore, crustacean ectoparasites seem to have strong interaction with the environment and host fish population, because these factors are directly invol- 9405 Seasonal infestation of Excorallana berbicensis Table 1. Body parameters of six fish of a reservoir from Araguari River basin, in the eastern Amazon region (Brazil). Season Fish species Acestrorhynchus falcirostris Ageneiosus ucayalensis Geophagus proximus Hemiodus unimaculatus Serrasalmus gibbus Psectrogaster falcata Length (cm) 18.2 ± 3.2 16.3 ± 2.8 14.4 ± 4.2 14.8 ± 2.3 10.9 ± 2.5 18.2 ± 3.9 Weight (g) 62.4 ± 36.0 39.7 ± 18.3 84.9 ± 77.5 51.5 ± 19.9 26.9 ± 36.6 138.4 ± 96.7 Dry Rainy N 44 48 4 42 12 35 N 18 15 10 14 24 30 Table 2. Physical and chemical parameters of the water in a reservoir from Araguari River basin, in the eastern Amazon region (Brazil). Different values in the same column indicate differences according to the Mann-Whitney test (U) at the 5% probability level. Precipitation: rainfall. NTU: nephelometric turbidity units. Dry season Rainy season Precipitation Transparency (mm) (m) 87.6 ± 52.4b 1.3 ± 0.3a 317.5 ± 194.1a 1.1 ± 0.1a Turbidity Conductivity pH (NTU) (µS/cm-1) 6.7 ± 1.9a 6.2 ± 0.5a 21.6 ± 2.8a 4.9 ± 2.1a 6.5 ± 0.2a 19.5 ± 0.9a ved in their different life cycles and may cause different responses to seasonal fluctuations in water levels. The dry season was from September to February and the rainy season was from March to August. However, the lowest rainfall rates occurred from September to November and the highest rates occurred from March to May, while the months of June through to August and December through to February were transitional periods between the two seasonality seasons. Although the levels of infestation by E. berbicensis were influenced by seasonality only in P. falcata, it was found when considering all hosts together that the prevalence of this ectoparasite presented a peak in the month of April, while the abundance showed two peaks, one in April and the other in August. These results possibly indicate that there are two reproductive cycles for E. berbicensis: one occurring in the rainiest month (April) and the other at the beginning of the transition period (August). Furthermore, the prevalence and abundance peaks of E. berbicensis also coincided with the reproduction period of these fish in the Araguari River basin region (Favero et al., 2010). Massive infestation of E. tricornis occidentalis was reported in E. striatus soon after their spawning (Semmens et al., 2006). In the region from Costa Rica, Guzmán et al. (1988) observed that E. tricornis occidentalis has a migration cycle over the course of the day, because were found mostly in the water column during the night and it migrates to the benthos during the day, particularly to coral habitats or rocky substrates, in areas under strong thermocline influence. Moreover, this marine coralla- Temperature (ºC) 28.9 ± 1.6a 26.5 ± 0.5a Dissolved oxygen (mg L-1) 5.2 ± 1.5a 5.2 ± 0.5a nid presented an influence weaker during the dry season (December to February). The high densities of these corallanid parasites also suggested that there was a seasonal effect relating to the beginning of the dry season. These authors concluded then that the nocturnal migration of these ectoparasites might be a form of behavior aimed at saving resources and might be related to predation of this isopod by fish and planktonic invertebrates. Despite of the life history of E. berbicensis is still little known, almost 70% of the specimens of this parasite on fish we collected during the rainy season. Although the migration of E. berbicensis to the water surface was not evaluated here, it was also found that there was greater presence of these parasites during nighttime. However, this migratory pattern still needs to be investigated. The condition factor is a quantitative parameter of fish wellbeing that is used in studies on the parasitehost relationship (Lizama et al., 2006; Guidelli et al., 2011; Vasconcelos & Tavares-Dias, 2014). It was not influenced by the rainy and dry seasons among the fish investigated here, due to low abundance of parasites. Similar results were reported for A. falcirostris and H. unimaculatus from eastern Amazon parasitized by E. turucuyus (Vasconcelos & Tavares-Dias, 2014). However, high infestation of E. tricornis occidentalis reduced the body condition of E. striatus in Costa Rica (Semmens et al., 2006), due to the high cost of parasitism to the hosts. Corallanid species have been considered to be temporary parasites that change hosts to feed (Bunkley-Williams & Williams Jr., 1998). 6941 Latin American Journal of Aquatic Research Table 3. Seasonal variation of infestation by Excorallana berbicensis in fish species in a reservoir from Araguari River basin, in the eastern Amazon region (Brazil). P: prevalence, MA: mean abundance, χ2: chi-square test for prevalence, U: Mann-Whitney test for mean abundance, P: probability. Dry season Hosts fish Acestrorhynchus falcirostris Ageneiosus ucayalensis Hemiodus unimaculatus Psectrogaster falcata Serrasalmus gibbus Geophagus proximus P (%) 15.9 33.3 35.7 25.7 33.3 0 MA 0.9 ± 3.0 1.7 ± 3.6 1.3 ± 3.6 2.2 ± 4.3 0.3 ± 4.3 0 Rainy season P (%) 38.9 40.0 7.1 53.3 12.5 40.0 MA 5.1 ± 17.3 2.9 ± 17.4 0.5 ± 19.1 6.8 ± 17.4 0.1 ± 18.4 8.5 ± 11.8 χ2 3.859 0.224 4.200 5.206 2.217 2.240 P 0.103 0.871 0.087 0.043 0.297 0.134 U 299.0 342.0 215.0 373.0 114.0 12.0 P 0.133 0.771 0.135 0.045 0.314 0.129 Table 4. Relative condition factor (Kn) for fish species in a reservoir from Araguari River basin, in the eastern Amazon region (Brazil). Values in the same line with different letters indicate differences according to the Kruskal-Wallis test (H). P: probability. Hosts fish Acestrorhynchus falcirostris Ageneiosus ucayalensis Hemiodus unimaculatus Psectrogaster falcata Serrasalmus gibbus Overall 1.00 ± 0.06a 1.00 ± 0.07a 0.99 ± 0.04a 1.00 ± 0.06a 1.00 ± 0.14a Dry season 1.00 ± 0.03a 1.00 ± 0.06a 1.00 ± 0.03a 1.00 ± 0.04a 1.00 ± 0.11a Rainy season 1.00 ± 0.09a 1.00 ± 0.07a 1.00 ± 0.03a 1.00 ± 0.05a 1.00 ± 0.08a H 0.272 0.159 0.008 0.091 0.134 P 0.873 0.923 0.996 0.955 0.935 Figure 2. Seasonal fluctuation of infestation by Excorallana berbicensis in fish species in a reservoir from Araguari River basin, in the eastern Amazon region (Brazil). Values above each column indicate the total number of hosts examined. Different letters in each line indicate differences according to the Dunn test (P < 0.05). *Indicate differences between prevalence according to the χ2 test (P < 0.05). Therefore, the lack of studies on the biology of isopods of the genus Excorallana makes exact interpretation of their relationship with their hosts difficult. In summary, since the physical and chemical characteristics of the artificial ecosystem investigated were relatively homogeneous, except for rainfall levels, this latter can be a factor causing the levels of infestation of E. berbicensis in P. falcata. Moreover, as P. falcata, A. falcirostris, A. ucayalensis, H. unimaculatus, G. proximus and S. gibbus presented seasonal variation of infestation by E. berbicensis on a temporal scale, and biological factors relating to these hosts and parasites seemed to be influencing these infestations. Seasonal infestation of Excorallana berbicensis Since homogeneous conditions among environmental parameters in the Amazon region are uncommon, additional studies using more than one seasonal cycle must be conducted to better comprehend the biology and ecology of this Corallanidae in fresh water. 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Health, 6: 362-364. Zar, J.H. 2010. Biostatistical analysis, Prentice Hall, New Jersey, 944 pp. Lat. Am. J. Aquat. Res., 43(5): 944-952, 2015 DOI: 10.3856/vol43-issue5-fulltext-14 Prebiotics in Nile tilapia diets 1 944 Research Article Growth, immune status and intestinal morphology of Nile tilapia fed dietary prebiotics (mannan oligosaccharides-MOS) Ricardo Yuji-Sado1, Fernanda Raulino-Domanski2 Patricia Franchi de Freitas1 & Francielli Baioco-Sales3 1 Universidade Tecnológica Federal do Paraná, 85660-000, Dois Vizinhos, PR, Brazil 2 Bolsista Iniciação Científica CNPq, Universidade Tecnológica Federal do Paraná 85660-000, Dois Vizinhos, PR, Brazil 3 Programa de Pós-Graduação em Zootecnia PPGZO Universidade Tecnológica Federal do Paraná 85660-000, Dois Vizinhos, PR, Brazil Corresponding author: Ricardo Yuji-Sado ([email protected]) ABSTRACT. Farmers must conform to Best Management Practices in fish production such as the development of non-antibiotic dietary supplements for fish growth and health management. We determined the effects of increasing levels of dietary mannan oligosaccharides on growth, immune system and intestine integrity of Nile tilapia. Fish (49.6 ± 10.8 g) were randomly distributed into 12 tanks (250 L; 20 fish per tank) and fed during 60 days with a practical diet supplemented with 0.0, 0.2, 0.4 and 0.6% dietary mannan oligosaccharides (n = 3). Fish growth and immune system were not affected (P > 0.05) by treatments. Fish fed 0.4% prebiotic supplementation presented increased (P < 0.05) intestinal fold height. Moreover, the intestine muscular layer thickness was increased in fish fed 0.4 and 0.6% dietary prebiotic. After 60 days, there were no effects on intestinal morphology. Studies regarding characterization of intestinal microbiota and experiment that reproduce commercial fish production systems hearing conditions are necessary to determine the effective use of this dietary supplement for the species. Keywords: Oreochromis niloticus, fish, oligosaccharides, nutrition, immune system, aquaculture. Crecimiento, estado inmunológico y morfología intestinal de la tilapia del Nilo alimentadas con prebióticos (mananoligosacáridos-MOS) en la dieta RESUMEN. Los acuicultores deben cumplir con buenas prácticas de gestión en la producción de peces, como el uso de probióticos en la dieta, dado que las prácticas amigables com el medio ambiente merecen atención creciente. Se determinó los efectos de los crecientes niveles de mananoligosacáridos en la dieta sobre el crecimiento, sistema inmunológico y morfología intestinal de la tilapia del Nilo. Los peces (49,6 ± 10,8 g) fueron distribuidos al azar en 12 estanques (250 L; 20 peces por estanque) y alimentados durante 60 días con una dieta práctica suplementada con 0,0; 0,2; 0,4 y 0,6% de mananoligosacáridos (n = 3). El crecimiento de los peces y el sistema inmunológico no fueron afectados (P > 0,05) por los tratamientos. En los peces alimentados com probióticos durante 30 días se encontraron alteraciones histológicas. Los peces alimentados con 0,4% de suplementación probiótica presentaron incremento (P < 0,05) de la altura de las pliegues intestinales. Además, el espesor de la capa muscular del intestino se incrementó en los peces alimentados con 0,4 y 0,6% de probiótico dietético. Después de 60 días no se observaron efectos sobre la morfología intestinal. Se requiere efectuar estudios relativos a la caracterización de la microbiota intestinal y experimentos que reproducen las condiciones de cultivo en los sistemas de producción de peces, para determinar el uso eficaz de este suplemento dietético para esta especie. Palabras clave: Oreochromis niloticus, peces, oligosacáridos, nutrición, sistema inmunológico, acuicultura. INTRODUCTION In animal production, including aquaculture, for decades antibiotics are usually used to prevent diseases __________________ Corresponding editor: Alvaro Bicudo outbreaks or/and as growth promoters in subtherapeutic dosage that can select bacterial strains with resistance to these antibiotics (Antibiotic Multiple Resistance-AMR) and already described in Brazil in 2945 Latin American Journal of Aquatic Research fish (Belém-Costa & Cyrino, 2006). Moreover, the growing concern in public health, fish farmers must conform to Best Management Practices (BMPs) in fish production for human consumption (Boyd et al., 2005). Attention start being given to the use of mannan oligosaccharides (MOS) derived from yeast Saccharomyces cerevisiae. These molecules are easily isolated from yeast cell wall as well as incorporated into fish feed and do not cause environmental impact (Hisano et al., 2004). The effects of dietary MOS on growth and health parameters have been recently performed in aquatic animals such as European sea bass Dicentrarchus labrax (Torrecillas et al., 2007), rainbow trout Oncorhynchus mykiss (Staykov et al., 2007), Nile tilapia (Sado et al., 2008), channel catfish Ictalurus punctatus (Peterson et al., 2010), Atlantic salmon Salmo salar (Refstie et al., 2010) and marron Cherax tenuimanus (Sang et al., 2011) and promising results such as improved weight gain, serum lysozyme concentration and disease resistance were observed. Fish immune system can recognizes non-selfmolecules (i.e., MOS prebiotic) through receptors that identify molecular patterns, which are characteristic of microbes (MAMPs-Microbe Associated Molecular Patterns) that stimulates fish leukocytes to produce lysozyme and others antimicrobial peptides (Song et al., 2014). Moreover, MOS provide mannose substrate upon which pathogenic gut bacteria selectively attach, impairing the adhesion to enterocytes, leading to better gut health and villi integrity and diet nutrients uptake (Ghosh & Mehla, 2012). The effect of dietary MOS on fish intestinal morphology was described for several economic important fish species (Dimitroglou et al., 2010a, 2010b; Genc et al., 2007; Pryor et al., 2003; Salze et al., 2008; Zhou et al., 2010) including the Brazilian Neotropical characin fish pacu, Piaractus mesopotamicus (Sado et al., 2014a). However, the use of MOS as prebiotic in fish nutrition is still in infancy as well as for the one of the most important fish in aquaculture, the Nile tilapia. Therefore, this study was set out to determine the effects of increasing levels of dietary MOS supplementation on growth, immune system and intestinal morphology of juvenile Nile tilapia. MATERIALS AND METHODS Experimental design and animals Trials were set up in water recirculation system, with continuous aeration and temperature control. Juvenile Nile tilapia (49.6 ± 10.8 g; 13.9 ± 7.1 cm) were randomly distributed into 250 L polyethylene circular tanks (20 fish per tank) in a totally randomized experimental design with four treatments, 0.0, 0.2, 0.4 and 0.6% MOS (YES-MOS®, YES - YesSinergy do Brasil Agroindustrial, Jaguariuna, Sao Paulo, Brazil) dietary supplementation (n = 3). Fish were acclimated to basal diet for 15 days prior experiment. Fish were fed with experimental diets for 60 days until apparent satiation (09:00 and 17:00h). Water quality parameters (pH 7.3 ± 0.4; dissolved oxygen 4.12 ± 0.52 mg L-1 and temperature 25.3 ± 1.2oC) were monitored electronically on a daily basis. Experimental diets A commercial fish feed formulation (PEIXES 32®, Anhambi Alimentos Ltda., Itapejara do Oeste, Parana, Brazil) was used for the basal experimental diets composition (Table 1). Into this basal diet it was added the respective treatments (0.0, 0.2, 0.4 and 0.6% dietary MOS) and extruded. The extruded feeds were dried in a forced ventilation oven at 45ºC for 24 h; and pellets were packed in black plastic bags and stored under refrigeration until use. Growth parameters At 30 and 60 days trial fish were fasted for 24 h and sedated for biometrical procedures and growth parameters calculated as follows: weight gain (WG (g) Table 1. Chemical composition of basal, practical diet (dry matter basis). *Anhambi Alimentos Ltda., Itapejara do Oeste, Parana, Brazil. Vitamin and mineral supplementation per kg of feed: calcium (min-max):14-34 g kg-1, phosphorous (min) 10 g kg-1, lysine 17 g kg-1, metionin 6100 mg kg-1, vitamin A (min) 15,000 UI kg-1, vitamin D3 (min): 3,000 UI kg-1, vitamin E (min): 180 mg kg-1, vitamin K3 (min): 6.0 mg kg-1, vitamin B1 (min): 18 mg kg-1, vitamin B2 (min): 32 mg kg-1 vitamin B6 (min): 22 mg kg-1, vitamin B12 (min): 40 mcg, vitamin C (min): 422 mg kg-1, nicotinic acid 150 mg kg-1, pantothenic acid 60 mg kg-1, folic acid (min): 10 mg kg-1, biotin (min): 1.50 mg kg-1, inositol (min): 238 mg kg-1, Fe (min): 65 mg kg-1, Cu (min): 10.40 mg kg-1, Zn (min): 130 mg kg-1, Mg (min): 65 mg kg-1, iodine (min): 1.30 mg kg-1, Se (min): 0.40 mg kg-1, cobalt (min): 0.35 mg kg-1, Sodium 2400 mg kg-1, choline 350 mg kg-1, antioxidant 200 mg kg-1, enzimatic aditive 125 mg kg-1. Levels of guarantee (according to the manufacturer*) Nutrient Moisture (max) Crude protein (min) Crude fat (min) Crude fiber (max) Ash (max) Content (g kg-1) 120 320 40 60 130 946 3 Prebiotics in Nile tilapia diets = FW-IW); feed consumption (FC); feed conversion rate (FCR = FC/WG); specific growth rate (SGR (% day-1) = 100 x [(lnFW-lnIW) / t]; feed efficiency (FE = WG/FC); daily feed intake index (DFI = 100 x {FC/ [(FW-IW)/2]} /t) and condition factor (CF = WG/ [total length]3). Where: FW = final weight (g); IW = initial weight (g); t = experimental time (days); lnFW = natural logarithm of final weight; lnIW = natural logarithm of initial weight. Growth parameters at 30 days trial was calculated taken in account the biomass of 20 animals and for 60 days, 18 fishes, since two fishes from each replicate was euthanized for histological procedures at 30 days of experiment. Histological procedures Histological procedures were performed at 30 and 60 days trial. A snippet of the proximal intestine (3.0 cm from pyloric sphincter) of two specimens from each treatment replicate was sampled. Tissue samples were washed with saline solution (0.6%) and fixed for 24 h in Alfac solution. After 24 h, fixed samples were stored in a 70% alcohol solution, dehydrated in ethanol, diaphanized in xilol and blocked in histological paraffin. Histological sections (5 µm) were stained with haematoxylin and eosin (H & E) and documented photographically with a digital camera (DCM 130E/1.3 megapixels, CMOS Software Scopephoto, China) connected to a light microscope (EDUTEC 502 AC, Brazil). The images were analyzed by using BEL Eurisko Software (BEL-Engineering, Italy) for intestinal fold height and muscular layer thickness measures. Immunological parameters Immunological analyses were performed at 30 and 60 days trial. Four fish from each tank were anesthetized in benzocaine solution (1:10,000) and blood samples were drawn from caudal vessel using sterilized syringes and separated into two 1.5 mL microtubes, one containing EDTA for leukocyte respiratory burst and the other with no anticoagulant for serum lysozyme and total protein concentration. Blood samples with EDTA were used for leukocyte respiratory burst by NBT (Nitroblue tetrazolium) colorimetric assay. To this, 100 µL of blood was added to 100 µL of 0.2% NBT solution (Sigma, St Louis, MO, USA), homogenized and incubated for 30 min at 25oC. After the incubation, 50 µL of this suspension was added to 1.0 mL of N, N-dimethylformamide (DMF, Sigma, St Louis, MO, USA) and centrifuged (755 g) for 5 min. The absorbance of the supernatant was determined using a spectrophotometer at 540 nm. Lysozyme concentrations (LC) were determined using fish serum from blood without EDTA based on the lyses of Micrococcus lysodeikticus microorganism by reduction of optical density during bacterial cell wall lyses. Prior to fish serum analysis, it was determined the calibration curve by quantification the difference of optical density (ΔOD) (0.5 to 5 min) of different concentrations of standard lysozyme (L 6876, Sigma, St Louis, MO, USA) according to Abreu et al. (2009). Serum samples were submitted to heat (56oC for 30 min) to inactivate complement system proteins and certify that lysis of M. lysodeikticus had occurred solely by lysozyme action. After this, 150 µL of fish serum and 150 µL sodium phosphate buffer was dispensed into glass cuvette and incubated at 26oC for 2 min in the spectrophotometer and 300 µL of M. lysodeikticus suspension (0.2 mg mL-1 sodium phosphate buffer) was added to complete 600 µL final volumes. Difference between the initial and final optical density (Δ OD) was measured between 0.5 and 5 min in spectrophotometer at 450 nm. The equation of lysozyme calibration curve was used to determine the serum lysozyme levels (µg mL-1). Total serum protein concentrations were determined using a portable refractometer (Biobrix 301/Protein 0.0-12 g dL-1) after blood sample without EDTA centrifugation and serum collection. Statistical analysis Significant effects of dietary MOS levels for 30 and 60 days were determined by one-way analysis of variance (ANOVA), at 5% probability. Brown and Forsythe and Shapiro-Wilk test, respectively validated the assumption of homogeneity of variance (homocedasticity) and normalit-y. Means of statistically difference were compared using Tukey's test (α = 0.05) (Steel & Torrie, 1980). This research was approved by the Ethics Committee on Animal Use (CEUA) of UTFPR (protocol No2014-001). RESULTS Dietary MOS supplementation for 30 and 60 days to juvenile Nile tilapia did not influenced (P > 0.05) growth parameters (Table 2). Histological analysis carried on this study revealed increase (P < 0.05) in intestinal fold height (Fig. 1) and muscular layer thickness (Fig. 2) between fish fed control diet and MOS supplemented diets for 30 days. Intestinal fold height was increased (P < 0.05) in fish fed dietary MOS when compared to fish fed control diet. Moreover, fish fed 0.4% dietary MOS presented 4947 Latin American Journal of Aquatic Research Table 2. Growth parameters (µ ± SD) of Nile tilapia O. niloticus fed increasing levels of dietary mannan oligosaccharide (MOS) for 30 and 60 days. *Mannan oligosaccharide-YES-MOS® (YES-YesSinergy do Brasil Agroindustrial, Jaguariuna, São Paulo, Brazil). WG: weight gain, FC: feed consumption, FRC: feed conversion rate, SGR: specific growth rate, FE: feed efficiency, DFI: daily feed intake index, CF: condition factor. MOS* % WG (g) FC (g) FCR SGR (% day-1) FE DFI (%) CF 0.0 797.5 ± 103.7 1161.6 ± 128.3 1.45 ± 0.04 1.93 ± 0.23 0.68 ± 0.02 1.66 ± 0,13 1.03 ± 0.20 MOS* % WG (g) FC (g) FCR SGR (% day-1) FE DFI (%) CF 0.0 1562.6 ± 59.1 2363.5 ±161.6 1.51 ± 0.05 3.11 ± 0.13 0.66 ± 0.02 2.55 ± 0.16 1.03 ± 0.14 30 days 0.2 0.4 965.1 ± 113.7 921.0 ± 54.2 1118.8 ± 122.6 1270.9 ± 11.3 1.17 ± 0.24 1.38 ± 0.06 2.40 ± 0.26 2.18 ± 0.12 0.87 ± 0.21 0.72 ± 0.03 1.60 ± 0.23 1.75 ± 0.04 0.95 ± 0.15 0.86 ± 0.08 60 days 0.2 0.4 1548.0 ± 40.5 1566.2 ± 71.2 2385.1 ± 249.6 2139.3 ± 216.6 1.53 ± 0.13 1.36 ± 0.16 3.30 ± 0.14 3.15 ± 0.06 0.65 ± 0.05 0.73 ± 0.09 2.71 ± 0.20 2.34 ± 0.29 1.07 ± 0.14 1.03 ± 0.15 0.6 905.1 ± 51.6 1261.6 ± 29.4 1.39 ± 0.10 2.07 ± 0.10 0.71 ± 0.05 1.70 ± 0.11 0.85 ± 0,19 P-values 0.128 0.182 0.163 0.096 0.224 0.642 0.549 0.6 1637.9 ± 144.5 2400.6 ± 165.4 1.46 ± 0.10 3.13 ± 0.20 0.68 ± 0.04 2.49 ± 0.06 1.04 ± 0.01 P-values 0.618 0.399 0.399 0.440 0.384 0.229 0.982 Figure 1. Intestinal fold height of Nile tilapia O. niloticus fed increasing levels of dietary mannan oligosaccharides (MOS) for 30 and 60 days trial. Different letters above same color columns indicate differences by Tukey test (α = 0.05). Figure 2. Intestinal muscular thickness of Nile tilapia O. niloticus fed increasing levels of dietary mannan oligosaccharides (MOS) for 30 and 60 days trial. Different letters above same color columns indicate differences by Tukey test (α = 0.05). the highest (P < 0.05) intestinal fold height (430.27 ± 89.72 µm) compared to others treatments: control (292.81 ± 45.11 µm), 0.2% (351.31 ± 56.00 µm) and 0.6% (348.23 ± 37.69 µm). Fish fed 0.4 and 0.6% dietary MOS had significant increasing in muscular layer thickness (72.5 ± 21.95 µm and 71.44 ± 24.48 µm, respectively). After 60 days trial there were no effects (P > 0.05) on gut morphology. Fish immunological parameters also did not influenced by dietary MOS (Table 3). Serum lysozyme concentrations (LC) were determined based on calibration curve equation (LC = 7150.7(Δ OD) + 50.793; R2 = 0.972). 948 5 Prebiotics in Nile tilapia diets Table 3. Immunological parameters (µ ± SD) of Nile tilapia O. niloticus fed increasing levels of dietary mannan oligosaccharide (MOS) for 30 and 60 days. *Mannan oligosaccharide-YES-MOS® (YES-YesSinergy do Brasil Agroindustrial, Jaguariuna, São Paulo, Brazil). Lys: serum lysozyme concentrations, Burst: leukocyte respiratory burst activity, Prot: serum total protein concentration, DO: optical density. MOS* % Lys (µg mL-1) Burst (DO) Prot (g dL-1) 0.0 1.50 ± 0.16 0.268 ± 0.01 5.38 ± 0.42 MOS* % Lys (µg mL-1) Burst (DO) Prot (g dL-1) 0.0 1.73 ± 0.18 0.304 ± 0.09 5.21 ± 1.37 30 days 0.2 0.4 1.50 ± 0.08 1.03 ± 0.38 0.269 ± 0.02 0.272 ± 0.02 5.78 ± 0.43 5.47 ± 0.52 60 days 0.2 0.4 1.67 ± 0.13 1.41 ± 0.21 0.346 ± 0.08 0.307 ± 0.07 5.85 ± 0.45 5.88 ± 1.06 DISCUSSION Prebiotics in aquaculture are used to enhance fish growth and disease resistance, improving economic viability and sustainability of fish farming (Ringø et al., 2010). Several studies have shown that dietary prebiotics enhances growth and health of aquatic animals (Sakai, 1999; Bricknell & Dalmo, 2005; Mazlum et al., 2011). Increased growth parameters in fish fed dietary MOS was observed in rainbow trout (Staykov et al., 2007), European sea bass (Torrecillas et al., 2007, 2011) and gilthead sea bream Sparus aurata (Gültepe et al., 2011). However, dietary MOS in fish nutrition are still controversial since some studies did not observe improvements on growth parameters. As herein observed, increasing levels of dietary MOS did not affect fish growth and similar results was observed for Nile tilapia supplemented for 45 days with 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0% (Sado et al., 2008) and 0.0, 1.0, 2.0 and 3.0% MOS for 53 days trial (Schwarz et al., 2010) as well as for pacu fed 0.2, 0.4, 0.6, 0.8, 1.0, 1.5 and 2.0% dietary MOS for 63 days (Sado et al., 2014a). In the same way, several authors observed no effects on growth in another fish species such as for Gulf of Mexico sturgeon Acipenser oxyrinchus desotoi fed 0.3% dietary MOS (Pryor et al., 2003), Atlantic salmon Salmo salar fed 1.0% dietary MOS (Grisdale-Helland et al., 2008), gilthead sea bream Sparus aurata fed 0.2 and 0.4% dietary MOS (Dimitroglou et al., 2010a) and giant sturgeon Huso huso fed 0.2 and 0.4% dietary MOS (Mansour et al., 2012). The variability in results found in literature may be explained by the complex carbohydrate structure present in the cell wall of yeast, different strains and fermentation conditions, processing methods can all 0.6 1.35 ± 0.04 0.268 ± 0.02 5.72 ± 0.26 P-values 0.245 0.986 0.196 0.6 1.49 ± 0.11 0.332 ± 0.07 5.81 ± 1.00 P-values 0.171 0.651 0.497 alter their function (Newman, 2007). Moreover, depending on MOS concentration, administration period, fish growing stage, rearing conditions, feed formulation and extrusion procedures different results can be presented (Pryor et al., 2003; Carvalho et al., 2011; Peterson et al., 2012; Torrecillas et al., 2014). Prebiotics are defined as short-chain carbohydrates that modulate the composition and metabolism of the microorganisms of the intestinal tract in a beneficial way (Macfarlane et al., 2006). They are non-digestible fibers by enzymes, acids and salts produced by the animals’ digestion process, acting as a substrate, stimulating the growth of beneficial bacteria in the gastrointestinal system, which produce acids, which decrease the concentration of bacteria and other pathogenic microorganisms and protect the intestinal mucosa (Song et al., 2014). This brings benefits to the host with improvements in growth, digestion of nutrients, immunity and resistance to disease (Burr & Gatlin 2005). Dietary MOS can enhance gut health by eliciting better intestinal development and increase nutrient absorption area and well documented in fish such as cobia (Salze et al., 2008), red drum (Zhou et al., 2010), gilthead sea bream (Dimitroglou et al., 2010a), white sea bream (Dimitroglou et al., 2010b) and Nile tilapia (Hisano et al., 2006; Carvalho et al., 2011), corroborating the results observed in this trial. Mannan oligosaccharides provide mannose substrate upon which pathogenic gut bacteria selectively attach. The inhibition of pathogenic bacteria adhesion to enterocyte prevents colonies formation and infection of host cells, increasing gut health, regularity, height and integrity of the gut tissue and consequent better utilization and absorption of nutrients (Pryor et al., 2003; Heidarieh et al., 2013). 6949 Latin American Journal of Aquatic Research Contradictory results was observed for hybrid tilapia (O. niloticus x O. aureus) (Genc et al., 2007) and pacu (Sado et al., 2014a) fed increasing levels of dietary MOS for 60 days and did not show improved fold height. In addition, Pryor et al. (2003) also did not find any significant difference in intestinal morphology of sturgeons fed 0.3% MOS supplementation for 28 days and similar results were reported by Torrecillas et al. (2007) for European sea bass fed diets containing 0.2 and 0.4% MOS for 48 days. Feeding 0.2 and 0.4% dietary MOS to gilthead sea bream also did not result in differences in gross intestinal and liver histology (Dimitroglou et al., 2010a). Although ultrastructural analysis were not performed, the increased fold height herein observed in fish fed dietary MOS for 30 days that did not reflect better growth could be explained by the impossibility to observe integrity of intestinal brush border and microvilli by optical microscopy (Sado et al., 2014a). Ultrastructural analysis of anterior intestine of cobia larvae fed rotifers enriched with 0.2% MOS showed increased microvilli height (Salze et al., 2008) as well as for gilthead sea bream fed 0.2 and 0.4% dietary MOS (Dimitroglou et al., 2010a) and red drum fed 1% dietary prebiotics such as MOS, FOS (fructooligosaccharides) and GOS (galactooligosaccharides) (Zhou et al., 2010). However, in both cases, in spite the fact that ultrastructural analysis showed increased density of microvilli structures and length that could improve the potential of nutrient absorption, dietary MOS did not influence the species’ growth rate and feed utilization. Moreover, white sea bream larvae fed artemia enriched with 0.2% MOS also showed improved intestinal microvilli surface (about 12%) and length (Dimitroglou et al., 2010b), but no effects on performance of fish were reported. Fish digestive system shows high phenotypic plasticity in response to diet composition, and it is more evident in omnivorous fishes (Gonçalves et al., 2011). Oligosaccharides such as MOS can increase mucus secretion by enterocytes that improves digest's viscosity (Torrecillas et al., 2011). Therefore, the increase in digest's viscosity could stimulate intestine's muscular layer development to move the alimentary bolus through digestive tract as herein observed. The innate immune system of fish can recognize non-self substances through protein recognition receptors that identify molecular patterns, which are characteristics of microbes (polysaccharides, lipopolysaccharide, peptidoglycans, bacterial DNA, and double-stranded viral RNA) and not ordinarily found on the surface of multicellular organisms, called Pathogen Associated Molecular Patterns-PAMPs (Rauta et al., 2014; Song et al., 2014). Mannan oligosaccharides are compounds isolated from cell wall of yeast Saccharomyces cerevisiae. Thus, it can stimulate fish immune system such as antibody production, leukocyte bactericidal, lysozyme and complement activity, as observed for rainbow trout (Staykov et al., 2007) and European seabass (Torrecillas et al., 2007). In the same way, Labeo rohita fish fed prebiotic for 28 and 42 days (Misra et al., 2006a) or intraperitoneal injection (Misra et al., 2006b) showed increase in lysozyme concentrations, demonstrating that time and via of administration can influence the prebiotic effect. Lysozyme is a molecule, primarily produced by leukocytes for protection against microbial infection, preventing bacteria invasion and infection (Saurabh & Sahoo, 2008). After phagocytosis initiates by leukocytes, increase in molecular oxygen consumption occurs, known as respiratory burst. In this process, the phagocytes produce reactive oxygen species that contribute for microorganism destruction (BillerTakahashi; Urbinati, 2014). However, in this trial it was observed no effect of dietary MOS on fish immune status. This results can be explained by the fact of the present work was performed under ideal controlled laboratory conditions and fishes were not challenged by biological and/or ambient stressor that reproduces intensive fish production system hearing conditions. In fact, when fish is exposed to biological challenge, the potential effect of dietary prebiotic on fish immune system can be expressed as observed for snakehead (Channa striata) fingerlings fed dietary prebiotics (MOS and glucans) and probiotics after challenge with Aeromonas hydrophila (Talpur et al., 2014). Dietary MOS did not influence serum total protein concentrations. However, rainbow trout fed dietary prebiotic for seven days showed increase in total plasmatic protein (Siwicki et al., 1994) as well as for L. rohita (Misra et al., 2006a, 2006b). In addition, pacu fed 0.2% dietary MOS also showed increased total plasmatic protein (Sado et al., 2014b). Total plasmatic protein represents several blood peptides such as lysozyme, immunoglobulins and albumin as well as complement factors (Misra et al., 2006a). Thus, the result regarding total plasmatic protein herein observed corroborate the absent of significant effect of treatments on serum lysozyme concentration. This study shows the potential and functionality of prebiotics compounds such as mannan oligosaccharides as dietary supplement for Nile tilapia to modulate gut morphology. However, further researches must focus experiments that reproduce commercial fish pro- Prebiotics in Nile tilapia diets duction systems hearing conditions are necessary to determine the effective use of this dietary supplement for the specie. ACKNOWLEDGMENTS To Yes Sinergy (Jaguaiuna, SP, Brazil) for providing the tested feed supplement-Yes-MOS®, Anhambi Alimentos Ltda. (Itapejara do Oeste, PR, Brazil) for providing the practical diet formulation and CNPq (Proc. 474153/2011-8) for financial support. 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Improved feed utilization, intestine mucus production and immune parameters in sea bass (Dicentrarchus labrax) feed mannan oligosaccharides (MOS). Aquacult. Nutr., 17: 223-233. Received: 22 December 2014; Accepted: 22 September 2015 9 952 Torrecillas, S., D. Montero & M. Izquierdo. 2014. Improved health and growth of fish fed mannan oligosaccharides: potential mode of action. Fish Shellfish Immunol., 36: 525-544. Zhou, Q.C., J.A. Buentello & D.M. Gatlin. 2010. Effects of dietary prebiotics on growth performance, immune response and intestinal morphology of red drum (Sciaenops ocellatus). Aquaculture, 309: 253-257. Lat. Am. J. Aquat. Res., 43(5): 953-962, 2015 Reproduction and egg quality in Seriola rivoliana DOI: 10.3856/vol43-issue5-fulltext-15 953 Research Article Reproductive broodstock performance and egg quality of wild-caught and first-generation domesticated Seriola rivoliana reared under same culture conditions Marcos F. Quiñones-Arreola2,1, G. Fabiola Arcos-Ortega1, Vicente Gracia-López1 Ramón Casillas-Hernández2, Charles Weirich3, Terry Morris3 Mariana Díaz-Tenorio2 & Cuauhtémoc Ibarra-Gámez2 1 Centro de Investigaciones Biológicas de Noroeste, S.C. (CIBNOR) Avenida Instituto Politécnico Nacional 195, Col. Playa Palo de Sta. Rita Sur La Paz B.C.S. 23096, México 2 Departamento de Ciencias Agronómicas y Veterinarias, Área de Acuicultura Instituto Tecnológico de Sonora, Ciudad Obregón, Sonora 85000, México 3 Empresa Rancheros del Mar, Carretera Pichilingue km 2.5, Lomas de Palmira La Paz, B.C.S. 23000, México Corresponding author: Vicente Gracia-López ([email protected]) ABSTRACT. Almaco jack, Seriola rivoliana as well as some related species is of great interest in marine fish aquaculture. However, there are few studies about their reproduction in captivity. In this research work, reproductive performance and egg quality in two groups of adult Seriola rivoliana, caught in the wild and domesticated-F1 analyzed and compared, reared under optimal maturation conditions in a commercial private Laboratory. A total of 28 wild adult (>5 kg) were caught at La Paz Bay, Baja California Sur, Mexico, and 30 adult domesticated-F1 broodstock (>5 kg), were obtained from an original stock of 1,000 juveniles (3.5 g body weight) produced at Kona Blue (Hawaii, USA) sea farm. Fishes were transported to the Rancheros del Mar commercial private hatchery, where they were grown to adult size. Both groups were evaluated during eight months (May to December 2012) and compared in terms of reproduction performance (total number of spawning events, monthly spawning frequency, total number of eggs, total number of eggs per mL, and fertilization rate), egg biochemical composition (total proteins, total lipids, total carbohydrates, and triacylglycerides) and egg diameter. Results indicated that wild caught broostock showed a better reproductive performance in terms of fertilization rate, total number of spawning, monthly spawning frequency and total number of eggs produced. However, biochemical composition and egg diameter did not show statistical differences (P < 0.05) between two groups. The reproductive performance of broodstock and quality of eggs analyzed in this study are important traits to improve the aquaculture management of this species. Keywords: Seriola rivoliana, reproductive performance, egg quality, wild-caught fish, domesticated fish, aquaculture. Desempeño reproductivo y calidad de huevos en reproductores de origen silvestre y domesticado-F1 de jurel Seriola rivoliana bajo las mismas condiciones de cultivo RESUMEN. El jurel Seriola rivoliana así como algunas especies relacionadas, son de gran interés en la acuicultura de peces marinos. Sin embargo, existen pocos estudios sobre su reproducción en cautiverio. En este trabajo se analizó y comparó el desempeño reproductivo y calidad del huevo en dos grupos de adultos de Seriola rivoliana, capturados en el medio silvestre y domesticados-F1 criados en óptimas condiciones de maduración en un laboratorio comercial. Un total de 28 adultos silvestres (>5 kg) se capturaron en la Bahía La Paz, Baja California Sur, México y 30 adultos de origen domesticado-F1 (>5 kg), se obtuvieron a partir de un lote de 1.000 juveniles (3,5 g de peso) producidos en la empresa Kona Blue (Hawái, EE.UU.) y transportados a la empresa Rancheros del Mar para su engorda y posterior maduración. Los reproductores de ambos orígenes, fueron evaluados durante echo meses (mayo a diciembre 2012) y comparados en términos de desempeño reproductivo (número de desoves totales, frecuencia mensual de desoves, número total de huevos, número total de huevos __________________ Corresponding editor: Alvaro Bicudo 954 Latin American Journal of Aquatic Research por mL, tasa de fertilización) y composición bioquímica del huevo (proteínas totales, lípidos totales, carbohidratos totales y triglicéridos), así como el diámetro del huevo. Los resultados obtenidos, indican que los reproductores de origen silvestre presentaron un mejor desempeño reproductivo en términos de porcentaje de fertilización, número total de desoves, frecuencia mensual de desoves y número total de huevos producidos. Sin embargo, la composición bioquímica y el diámetro del huevo no mostraron diferencias estadísticas (P < 0,05) entre los dos grupos. El desempeño reproductivo y la calidad de los huevos analizados en este estudio son aspectos importantes para mejorar el manejo en cautiverio de esta especie. Palabras clave: Seriola rivoliana, desempeño reproductivo, calidad de huevos, peces silvestres, peces domesticados, acuicultura. INTRODUCTION World fishery production in marine waters was 82.6 million ton in 2011 and 79.7 million ton in 2012 (74.3 and 75.0 million ton excluding anchovy). Between 1980 and 2012, world aquaculture production volume increased at an average rate of 8.6 percent per year (FAO, 2014). World food fish aquaculture production more than doubled from 32.4 million ton in 2000 to 66.6 million ton in 2012. According to the latest information, FAO estimates that world food fish aquaculture production rose by 5.8% to 70.5 million ton in 2013 (FAO, 2014). Longfin yellowtail Seriola rivoliana as other Seriola species is considered as one of the most important emerging marine finfish species in Japan, Australia and the United States (Roo et al., 2014). In the American Pacific, Seriola rivoliana is distributed from the United States to Peru (Eschmeyer et al., 1983; Peterson et al., 1999) and in the Atlantic, from the US to Argentina (Cervigón, 1993). Almaco jack has excellent aquaculture potential due to its adaptability to captivity, fast growth, and high market value, but information about rearing this species in captivity is limited (Kolkovski & Sakakura, 2004; Roo et al., 2014). Sexual maturation under different culture conditions has been studied in different Seriola species, including S. lalandi (Poortenaar et al., 2001), S. rivoliana (Blacio et al., 2003, Roo et al., 2014) and S. dumerilli (Roo et al., 2009). A major constraint on the development of aquaculture for several Seriola species is their insufficient supply of eggs and the variable quality of larvae (Yamamoto et al., 2008). Successful conditioning of broodstock remains a crucial step to produce a large quantity of eggs and good-quality larvae in this species. In fish as in other marine organisms, such as crustaceans and mollusks, several factors affect the quality of eggs and larvae. These factors may be endogenous (genotype origin, age, and size of broodstock) or exogenous (egg size, egg management, broodstock feeding, bacterial colonization of egg surface) (Ballestrazzi et al., 2003; Kamler, 2005). Differences between egg batches often become apparent only well after their collection. Many studies of marine organisms have used physical, biological, or biochemical parameters as indicators of broodstock reproductive performance and egg quality (Arcos et al., 2003, 2009, 2011; Evans et al., 1996; Kjørsvik et al., 2003; Sangsawangchote et al., 2010). Among teleost’s, dietary components, such as proteins and lipids, have been implicated in various reproduction-related processes, such as gonadal maturation, gamete quality, and spawning performances (Izquierdo et al., 2001; Coward et al., 2002; Varghese et al., 2009; Korwin-Kossakowski, 2011). Assessing the reproductive physiology of Seriola spp., broodstocks are important goals to improving the culturing of these fish. First-generation domesticated “Hawaiian” (Seriola rivoliana) broodstock are already being reared for commercial production at the Rancheros del Mar hatchery in La Paz, Baja California, Mexico. This facility has achieved natural spawning of both wildcaught and domesticated broodstocks. However, maintaining actively spawning stocks of wild-collected S. rivoliana has proven difficult due to their susceptibility to a number of parasitic and bacterial pathogens. Domesticated (S. rivoliana) broodstocks appear to be substantially different from their wild counterparts (Rancheros del Mar, pers. comm.). The present study analyzed the reproductive performance and egg quality of wild-caught and firstgeneration domesticated populations of S. rivoliana, under same maturation conditions in the Rancheros del Mar commercial hatchery. A multidisciplinary approach was used to evaluate possible differences in adult reproductive performance between populations. Egg biochemical composition was used as an indicator of broodstock nutritional and physiological condition. MATERIALS AND METHODS Broodstocks and rearing system The study was carried out from May to December 2012. A total of 28 wild-caught adult S. rivoliana (>5 kg) were captured near the south coast of Bay La Paz, Baja California Sur, Mexico, and transported to the Rancheros Reproduction and egg quality in Seriola rivoliana del Mar commercial private hatchery (24°14’N, 110°18’W). In addition, 30 S. rivoliana first-generation domesticated individuals (>5 kg) were obtained from an original stock of juveniles (average 3.5 g body weight) brought from Kona-Blue Water farms in Hawaii and transported to the Rancheros del Mar commercial private hatchery. At the beginning of the reproductive season, the wild caught group had an average body weight of 9.1 kg, whiles the domesticated-F1, had 5.5 kg. Each group was distributed into 55 m3 circular fiberglass blue tanks with no more than 5 kg per metric ton of stocking density. Fish were kept under artificial photoperiod conditions (12 h light, 12 hours dark). Water was exchanged in each tank 18 times per day, using a closed recirculation system at 95%. Salinity was 36 g L-1 and temperature ranged from 26 to 26.5oC year-round. After capture, fish were weighed, measured, and sexed by introducing a polyethylene cannula (1.6 mm e.d.) into the oviduct and oocyte samples were preserved in Davidson solution in seawater. Fish were fed daily with commercial pellets (13 mm, Vitalis Repro™: Skretting, Burgos, Spain) corresponding to 1% of body weight (BW), supplemented with frozen squid, sardine, and mackerel, adjusted to equal a total daily supply equivalent to 2% of their BW. The collector tanks of eggs with an 800 µm mesh size bags, were placed on the perimeter of the broodstock tanks (one per tank of each origin). Egg collectors were monitored early each morning, and the floating eggs were collected by overflow of a side opening of the broodstock tank due to the positive buoyancy of the eggs. Reproductive performance of broodstocks Reproductive performance of each broodstock type (wild-caught and domesticated) was evaluated in terms of total number of spawning events, spawning frequency per month, total number of eggs, volume of floating eggs (mL), and fertilization rate. Total BW of each broodstock was recorded before they were returned to the maturation tank at the beginning of the spawning season. The survival rate of each group was measured until the end of the experimental evaluation (8 months). Every day, the spawns were sampled and recorded. Eggs were separated into floating and non-floating in a measuring cylinder, and the volumes and number of eggs were counted. Floating eggs were removed by 500 µm mesh, washed thoroughly, and subsequently kept in seawater that had been UV treated. The eggs were observed under a stereo microscope to assess the 955 morphology, fertilization success, and embryological stage. Fertilization rate was assessed taking three 5 mL samples from each spawning, and eggs with normal cleavage were counted. Fertilization rate was calculated as follows: Fertilization rate = Number of fertilized eggs ∗ 100 Total number of eggs Hatching rate was calculated by the counting of larvae (after 24 h of the spawn) versus fertilized eggs: Hatching rate = Total number of larvae ∗ 100 Total number of fertilized eggs Egg diameter Egg samples from each spawning of the two groups were collected every day during the 8-month experimental period and preserved in Davidson solution. From the fixed samples, eggs were observed and photos of each spawn event were taken using a fluorescence microscope Olympus BX41 (magnification 10x) connected to a video camera (CoolSNAP-ProColor). The recorded images were digitized using an image analysis program (Image Pro Plus, v.6.0). Egg measurements were performed from digitized images and Image-Pro® analysis software. Fifty eggs were measured daily for each group (Fig. 1) Egg biochemical analyses In order to perform biochemical analysis, an approximately 200 mg egg mass from each of the two populations was concentrated using a 75-µm mesh filter and frozen at -80°C for later analysis. Samples of eggs were weighed and individually homogenized in equal volumes of a buffer solution [0.05 M Tris, 0.5 M NaCl, 5 mM EDTA, pH 7 (3:1 v/v buffer: tissue)], and a protease inhibitor cocktail (0.003% ref. P2714, Sigma, St. Louis, MO, USA), using a FAST PREP-24 homogenizer for 1 min. The homogenate was centrifuged at 10,000 g for 15 min at 4ºC (Beckman ultracentrifuge, Pasadena, CA, USA), and the supernatant was stored at -80ºC for later quantification of total proteins (P), total lipids (L), total carbohydrates (C), and triacylglycerides (Tg). Enzymatic and colorimetric analyses adapted for small micro plates (Palacios et al., 1998) were performed, and the quantification of P was realized (Bradford, 1976) after digestion in 0.1 N NaOH. Carbone was quantified by the Anthrone method, after precipitation of proteins with trichloroacetic acid (Roe, 1955). Lipids were measured according to the sulfophosphovanillin method (Barnes & Blackstock, 1973) and Tg was quantified using a kit (GOD-PAP, Merck). 956 Latin American Journal of Aquatic Research Figure 1. Measurement and recording of the oocytes diameter from digitized images (4x). Statistical analyses Broodstock reproductive performance First, single-factor fixed ANOVA analysis was used to assess differences in broodstock reproductive performance variables (total number of spawning events, spawning frequency per month, total number of eggs, total number of eggs per mL, fertilization rate, and average egg diameter) between the two population groups. The factor “broodstock type” was considered with two levels, wild-caught and domesticated populations. A post-hoc Tukey’s test for multiple comparisons of means was used in cases in which the results of ANOVA were significant. Next, ANCOVA analysis was used to assess differences in the reproductive performance between the two population groups. The factor “broodstock type” was considered with two levels, wild-caught and domesticated populations, but female total weight was introduced as a covariate. Mean comparisons were performed by specific contrast of least square means, and adjusted means. Egg diameter Two different ANOVA models were used for morphometric and biochemical egg variables. First, single-factor fixed ANOVA was used for morphometric variables, including egg diameter. For the independent variable “broodstock type”, there were two levels, wild-caught and domesticated populations. A post-hoc Turkey’s test for multiple comparisons of means was realized in cases in which the results of ANOVA were significant. In addition, ANCOVA analysis was conducted for biochemical composition of eggs. The same factor “broodstock type” was considered with the two levels, but female body weight and egg diameter were introduced as covariates. Mean comparisons were performed using a specific contrast of least square means, and adjusted means are presented. Pearson’s correlation was applied to establish the relationship between the broodstock reproductive performance variables and egg variables (morphometric and biochemical composition). For all ANOVA analyses, biochemical data was transformed to logarithm base 10 to fit a normal distribution, and the percentage fertilization data was transformed to arcsine (Zar, 2010), before analyses. Means and back-transformed means are presented and the standard errors are those obtained from untransformed variables. Statistical significance was preset at P < 0.05, although P values obtained are indicated. Statistical analyses were performed with the General Linear Model module in Statistica version 10 (StatSoft Inc., Tulsa, OK, USA). Reproduction and egg quality in Seriola rivoliana RESULTS Broodstock reproductive performance There were significant differences between wild-caught and domesticated broodstocks in all measured reproductive variables (Table 1). The total weight of wild-caught broodstocks was significantly higher than that of the domesticated broodstocks. Wild-caught broodstocks showed a greater spawning frequency and produced more eggs, but the eggs of both populations were the same size. No differences in broodstock survival at the end of the 8-month experimental evaluation were observed. Egg diameter Although no significant differences were found in the egg diameter average between eggs from the different broodstocks, the wild caught group showed average values slightly higher over time, and more spawning’s during the same period (Table 1). Egg biochemical analyses There was no difference between the two groups in the total content of proteins, lipids, carbohydrates, or triacylglycerides (Table 2). The proportion of carbohydrates was very low in eggs of both broodstock types, compared with the amounts of proteins and lipids. Correlations among reproductive performance variables Correlations among the reproductive performance variables evaluated in both populations are shown in Table 3. There were significant positive correlations between total female weight of wild-caught individuals and fertilization rate (0.518), total number of spawning events (0.732), total number of eggs (0.963), and diameter of eggs (0.950). The total number of eggs was significantly correlated with the fertilization rate (0.936) and the total number of spawning events (0.857). Positive correlations among the same reproductive performance variables were also observed in domesticated broodstock. Correlations among reproductive performance variables and egg variables Correlations among all egg quality variables and between all reproductive performance variables and egg variables for the two broodstocks populations are shown in Table 4. The highest values and the most consistent correlations were found between wildcaught female total weight and protein in comparison with domesticated broodstock respectively (0.982), (0.965); lipid (0.917), (0.891); and triacylglycerides 957 (0.794), (0.738), respectively. Significant positive correlations were observed between the two factors egg diameter and fertilization rate with the three biochemical variables proteins, lipids, and triacylglycerides. The total number of eggs was significantly correlated with proteins and lipids for both broodstock populations. There were also correlations between the total number of spawning events and proteins, lipids, and triacylglycerides. DISCUSSION The costs of feeding and maintaining Seriola spp. broodstock are high; thus, it is desirable to develop a methodology to compare different broodstock types in order to select broodstock with high reproductive performance and high egg quality. In this study, a multidisciplinary approach was used to evaluate possible differences in reproductive performance and egg quality between wild-caught and domesticated broodstock populations. Significant differences in total BW, fertilization rate, total number of spawning events, monthly spawning frequency, total number of eggs, and total number of egg per mL were observed between wildcaught and domesticated broodstocks. Some morphometric variables regarding females or eggs could be used as non-invasive predictive criteria to select females with higher reproductive performance. For example, in our study, females with a greater total weight had a higher spawning capacity. However, this evaluation should be applied only to homogeneous populations (of the same age and reared under the same culture conditions) and should be further evaluated. Such a selection procedure could be combined with other criteria, such as biochemical levels in eggs. It is known that lipids, followed by proteins, are the major sources of energy available in vitellus for embryogenesis (Evans et al., 1996; Kjørsvik et al., 2003; Kamler, 2005). More studies are needed to evaluate the value of total protein levels as predictive criteria in Seriola spp. Several studies of fish have used biochemical components of eggs as indices of quality, particularly lipids, which perform energetic and structural functions during embryonic development (Kamler, 2005). In this study, no differences were observed between two different broodstocks in the amount of proteins, lipids, carbohydrates, or triacylglycerides in eggs, indicating not only that females transfer biochemical reserves to eggs, but also that wild-caught and domesticated females produce good quality eggs. This finding is reinforced by the observation of good egg quality in terms of the L and Tg content of eggs obtained from these females. Previous studies have reported the rela- 958 Latin American Journal of Aquatic Research Table 1. Reproductive performance of Seriola rivoliana wild-caught and first-generation domesticated broodstocks evaluated for 8 months. Mean values (± standard error) of the variables are presented. Different superscripts indicate significant differences according to Tukey’s test or specific contrast of least squares for multiple comparisons of means (P < 0.05). ANCOVA significance for the covariate (female body weight) is presented in the second column Broodstock types Total body weight (kg) Survival during 8 months (%) Fertilization rate (%) Total number of spawning Monthly spawning frequency (%) Total number of eggs (× 103) Total number of eggs (mL) Egg diameter (µm) Wild-caught 9.1 ± 2.3a 92.8 ± 1.4 94.5 ± 1.9a 57.0 ± 2.0a 9.2 ± 2.0a 610.44 ± 2.5a 612.28 ± 2.1a 1044.87 ± 22.8a Domesticated 5.5 ± 1.1b 90.0 ± 2.0 75.3 ± 2.8b 28.0 ± 1.0b 5.5 ± 1.0b 163.79 ± 6.6b 164.44 ± 6.4b 1035.83 ± 20.8b ANOVA ANCOVA P < 0.01 P < 0.05 P < 0.01 P < 0.01 P < 0.01 P < 0.01 P < 0.01 P > 0.05 P < 0.05 P < 0.01 P < 0.01 P < 0.01 P < 0.01 P < 0.01 P > 0.05 Table 2. Overall comparisons of the total content (mean ± standard error) of proteins (P), lipids (L), carbohydrates (C), and triacylglycerides (Tg) in the eggs of wild-caught and first-generation, domesticated, Seriola rivoliana females. N = 28 wildcaught females and 30 domesticated females. ANCOVA significance for the covariate (egg diameter) is presented. Variable -1 P (mg g ) L (mg g-1) C (mg g-1) Tg (µg g-1) Wild-caught Domesticated ANOVA ANCOVA 120.41 ± 2.5 151.07 ± 4.9 5.51 ± 1.5 57.7 ± 1.3 113.44 ± 2.5 167.38 ± 4.8 5.94 ± 1.5 53.35 ± 1.06 P > 0.05 P > 0.05 P > 0.05 P > 0.05 P > 0.05 P > 0.05 P > 0.05 P > 0.05 tionship between egg biochemical composition and the performance of the resulting larvae (Evans et al., 1996; Kjørsvik et al., 2003); therefore, it is expected that both broodstock types would produce high-quality larvae when egg biochemical components are high. The proportion of carbohydrates was very low in both types of eggs, compared with the amounts of proteins and lipids. Apparently, this component is not an important source of energy during embryonic development; it may play a greater role in later structural growth (Salze et al., 2005). No differences were observed in egg biochemical composition between the broodstock types; however, it has been reported that egg quality decreases over time in production. Therefore, the 8 months that elapsed during this study could have affected egg quality measurements. We do not know whether a longer period of evaluation in which more first spawning events occurred would produce a different result. To compare reproductive performance and egg quality between wild-caught and domesticated broodstocks, female total weight, and egg diameter were used as covariates. The choice of these covariates was justified by the positive correlations found between female total weight and all reproductive performance variables and biochemical components analyzed, and between egg diameter and the biochemical components. Our ANCOVA analysis used female total weight and/or egg diameter as covariates to analyze reproductive performance and egg quality variables between different broodstock types, independently of female weight or egg size. The use of covariates to correct data is common among animal breeders when estimating differences in parameters (Anang et al., 2001). This improvement in the estimation of the parameters by the use of covariates has been observed in other marine species studies (Perez-Rostro & Ibarra, 2003a, 2003b). In shrimp and fish, some of the common effects on reproduction variables indicate that correction or an adjustment of data by the use of covariates is needed (Ojanguren et al., 1996; Arcos et al., 2003). Positive correlations between broodstock weight or length and egg traits have also been reported for various other fish species, as rainbow trout, bighead carp, Nile tilapia, and channel catfish (Huang & Gall, 1990; Bolivar et al., 1993; Walser & Phelps, 1993; Estay et al., 1994). A surprisingly large positive correlation was obtained between female weight and the amounts of proteins, lipids, carbohydrates, and triacylglycerides in their eggs, suggesting that female weight plays an important role in egg quality. Reproduction and egg quality in Seriola rivoliana 959 Table 3. Pearson’s correlation coefficient (r) between reproductive performance variables assessed for wild-caught and first-generation broodstocks, domesticated females and the reproductive performance parameters of each group of females. *Significant correlation (P < 0.05). Wild-caught broodstocks Female total weight (kg) Fertilization rate (%) Total number of spawning events Total number of eggs Egg diameter (µm) Domesticated Broodstocks Total female weight Fertilization rate (%) Total number of spawning events Total number of eggs Egg diameter (µm) Female total weight (kg) Fertilization rate (%) Total number of spawning events Total number of eggs Egg diameter (µm) 0.518* 0.732* 0.963* 0.950* 0.207 0.936* 0.545 0.857* 0.250 0.478 - 0.439* 0.718* 0.889* 0.918* 0.339 0.871* 0.414 0.894* 0.301 0.369 - Table 4. Pearson’s correlation coefficient (r) between biochemical variables assessed in the eggs of wild and domesticatedF1, females and the reproductive performance parameters of each group of females. *Significant correlation (P < 0.05). Proteins (P), lipids (P), carbohydrates (C), and triacylglycerides (Tg). Eggs from wild-caught females P (mg g-1) L (mg g-1) C (mg g-1) Tg (mg g-1) Eggs from domesticated females P (mg g-1) L (mg g-1) C (mg g-1) Tg (mg g-1) Total female weight (kg) 0.982* 0.917* 0.237 0.794* Fertilization rate (%) 0.639* 0.701* 0.120 0.731* Total number of spawning events 0.513 0.593 0.101 0.492 Total number of eggs 0.852* 0.845* 0.180 0.774 Egg diameter (µm) 0.998* 0.661* 0.207 0.701* 0.965* 0.891* 0.149 0.738* 0.714* 0.695* 0.222 0.593* 0.422 0.534 129 0.492 0.731* 0.701* 0.151 0.695 0.997* 0.647* 0.260 0.685* Furthermore, a positive correlation between body weight or body length and number of eggs has also been reported in fish (Huang & Gall, 1990), and was observed in the present study. Some studies have shown that female size and spawning time affect egg size, fecundity, and egg viability (Kamler, 2005; Sangsawangchote et al., 2010). Typically, teleosts show a trade-off between egg number and size, but during a spawning season, the sizes of eggs in successive batches may differ (Evans et al., 1996; Kamler, 2005), although Kamler (2005) also reported no effect of egg batch sequence. In the present study, egg number and size were not significantly correlated. In some fish, such as Atlantic halibut (Hippoglossus hippoglossus), egg biochemical composition was size dependent (Evans et al., 1996), although in other fish species, such as Pseudopleuronectes americanus, the amounts of protein and lipids in the eggs were independent of egg size (Buckley et al., 1991). In this study, however, the biochemical composition of eggs from both populations was highly correlated with egg size. Our preliminary estimate of the correlation between reproductive performance and egg quality variables from different broodstock types indicated an association between these variables. Therefore, some females spawn more and faster, or produce eggs with higher quality. By selecting the females that display those traits for use in aquaculture, hatchery managers can increase egg production and egg quality. Egg diameter is easily measured and is one of the most frequently reported quality criteria in studies of marine reproductive biology (Kamler, 2005). The biochemical composition of eggs, particularly the composition of yolk components, which support the energetic and structural needs of developing embryos, is also a useful indicator of egg quality (Fraser, 1989; Racotta et al., 2003). The Tg concentration is an indicator of nutritional status and therefore a predictor 960 Latin American Journal of Aquatic Research of survival among fish larvae. Hilton et al. (2008) reported greater Tg reserves in eggs and larvae of fish that developed faster. Tg levels in eggs also can be used to infer the nutritional status of broodstocks (Hilton et al., 2008; Saito, 2012). The proper development of eggs depends on the biochemical reserves that are transferred to the eggs from the female. As the levels of these reserves could determine larval quality at a later stage, the quantities of those reserves may be considered indicators of future larval quality (Racotta et al., 2003). The biochemical composition of the egg itself could indicate the quantities of nutrients transferred to that egg. Arcos et al. (2003) found higher fecundity and fertilization rates and higher levels of triacylglycerides and vitellin in the eggs, of the first spawning of females that later had multiple spawns. They proposed that those traits could be used as non-invasive predictive criteria to select females with high reproductive quality. Further studies on predictive criteria are needed in Seriola culture species. A capacity for multiple spawning events within a reproductive season has been demonstrated in several Seriola species and is a promising trait for aquaculture (Poortenaar et al., 2001). CONCLUSIONS This study indicates that broodstock from a wild-caught population of S. rivoliana was in better physiological condition than that of a domesticated population in terms of morphometric production variables (body weight, fertilization rate, total number of spawning events, spawning frequency per month, and total number of eggs produced). However, biochemical composition of eggs was the same for both populations. Our results confirm that the physiological condition and egg quality of fish were not affected by Rancheros del Mar hatchery conditions, and the reproductive performance and egg quality could even be improved with the use of a specific diet. The egg and female quality variables analyzed in this study are important reproductive traits that are applicable to programs to improve the culturing of this species. ACKNOWLEDGMENTS The authors are grateful to Rancheros del Mar of La Paz for providing the S. rivoliana spawns and for permitting the evaluation of the broodstocks. We gratefully acknowledge the staff of the Rancheros del Mar Hatchery: Chuck, Arturo, José, Raúl, and Chepina. In addition, we would thank Roberto Hernandez and Carmen Rodriguez-Jaramillo for their invaluable technical support during this study and the staff of the Laboratory of Marine Fish Reproduction at CIBNOR for their support during the first experimental trials with this species: Tec. Francisco Encarnación Ramírez, M.C. Gerardo González, and M.C. Ana Trasviña. This research was supported by grants to CONACYT. 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Am. J. Aquat. Res., 43(5): 963-971, 2015 Dietary B. amyloliquefaciens in cage-reared tilapia DOI: 10.3856/vol43-issue5-fulltext-16 963 Research Article Effects of the probiotic Bacillus amyloliquefaciens on growth performance, hematology and intestinal morphometry in cage-reared Nile tilapia Thiago Fernandes A. Silva1, Thalita R. Petrillo2, Jefferson Yunis-Aguinaga1, Paulo Fernandes Marcusso2, Gustavo da Silva Claudiano2, Flávio Ruas de Moraes2 & Julieta R. Engrácia de Moraes1,2 1 Aquaculture Center of Unesp, São Paulo State University (Unesp), Jaboticabal, Brazil Via Prof. Paulo Donato Castellane, km 05, Jaboticabal, SP. 14.884-900 2 Department of Veterinary Pathology, São Paulo State University (Unesp), Jaboticabal, Brazil Corresponding author: Julieta Engrácia de Moraes ([email protected]) ABSTRACT. The aim of this study was to evaluate the effect of probiotic Bacillus amyloliquefaciens on the growth performance, blood profile and intestinal morphometry in Nile tilapia (Oreochromis niloticus) reared in cages. 936 Nile tilapias were distributed in 12 cages (1.5 m3). Fish were fed for 90 days on basal diets containing 0 (control); 1×106 CFU g-1; 5×106 CFU g-1; and 1×107 CFU g-1 of the probiotic. The results showed no significant difference on performance and proximal composition of fish. Blood glucose and hemoglobin were lower in 1×107 CFU g-1 group, suggesting improves of the homeostatic state of the fish. Other hematimetric indices did not differ between groups. It was observed significant increase of villi height and in the number of goblet cells of the intestine in fish supplemented 5×106 CFU g-1 and 1×107 CFU g-1 of food suggesting that fish improved the digestion and absorption of nutrients. However, more studies are needed to determine the efficacy of this probiotic in field conditions in Nile tilapia. Keywords: Oreochromis niloticus, homeostatic state, intestinal morphology, blood glucose, aquaculture. Efectos del probiótico Bacillus amyloliquefaciens en el crecimiento, hematología y morfometría intestinal en tilapias del Nilo criadas en balsa jaula RESUMEN. El objetivo de este estudio fue evaluar el efecto del probiótico Bacillus amyloliquefaciens en el desempeño del crecimiento, hemograma y morfometría intestinal en tilapia del Nilo (Oreochromis niloticus) criadas en balsas jaulas. 936 tilapias del Nilo se distribuyeron en 12 balsas jaulas (1,5 m3). Los peces fueron alimentados durante 90 días con dietas que contenían 0 (control); 1×106 UFC g-1; 5×106 UFC g-1 y 1×107 UFC g-1 del probiótico. Los resultados no mostraron diferencias significativas en el rendimiento y composición proximal de los peces. La glucosa en sangre y hemoglobina fue menor en el grupo 1×107 UFC g-1, lo que sugiere un mejor estado homeostático de los peces. Otros parámetros hematimétricos no difirieron entre los grupos. Se observó aumento significativo de la altura de las vellosidades y número de células caliciformes del intestino en los peces suplementados con 5×106 UFC g-1 y 1×107 UFC g-1 de alimento que sugieren que los peces mejoraron la digestión y absorción de nutrientes. Sin embargo, se necesitan más estudios para determinar la eficacia de este probiótico en condiciones de campo en tilapia del Nilo. Palabras clave: Oreochromis niloticus, homeostasis, morfología intestinal, glucosa sanguínea, acuicultura. INTRODUCTION Nile tilapia reared in cages presents advantages over traditional pond and tank systems due to the easier handling, high volume of production, and use of areas unsuitable for other purposes, and the biological characteristics of this species (García et al., 2014). Al__________________ Corresponding editor: Mauricio Laterça though the productivity advantages (Kim et al., 2014), fish at high stocking densities may present stress and depress the immune system, increasing susceptibility to bacterial and parasitic diseases (Telli et al., 2014). The use of antibiotics as prophylactic is questioned for being a source of environmental pollution (Ayandiran et al., 2014), accumulating in the fillet, and promoting 964 Latin American Journal of Aquatic Research resistance to drugs with risks to human and animal health (Kersarcodi-Watson et al., 2008). Probiotics are live microorganisms able to establish, multiply and colonize the intestine of the host in order to promote a beneficial balance of microorganisms. These benefits are explain due to these microorganisms inhibit the proliferation of harmful agents in the intestinal mucosa, improve the digestibility and absorption of nutrients (Nayak, 2010), promote the synthesis of vitamins (Lee et al., 2013), and improve the growth performance of animals (Mohapatra et al., 2014) by increasing the survival percentage (Wu et al., 2014) and water quality (Chi et al., 2014). Bacteria from genus Bacillus are one of the main probiotics used in aquaculture. These bacteria are ease to cultivate and form spores, which facilitates its conservation (Wang et al., 2008; Nayak, 2010; Han et al., 2015). In addition, several bacteria of this genus have the capacity to secrete antimicrobial compounds and different exoenzymes that aid digestion (ZiaeiNejad et al., 2006). Bacillus amyloliquefaciens (ex Fukomoto, 1943) Priest et al., 1987 is a non-pathogenic bacterium rodshaped, aerobic, Gram-positive, and catalase positive (Loncar et al., 2014). This bacterium is highly resistant to environmental changes (Mahdhi et al., 2012; Das et al., 2013), presents antibacterial activity of broad spectrum (Kaewklom et al., 2013), and is an important producer of α-amylase, an enzyme that acts in the digestion of carbohydrates (Wang et al., 2008). Recently, in studies with B. amyloliquefaciens Reda & Selim (2015) observed in O. niloticus reared in laboratory conditions; improve in body composition and intestinal morphology. Ridha & Azad (2012) reported in the same fish improvements on growth performance and immune response. Cao et al. (2011) observed in Anguilla anguilla, antagonist activity of B. amyloliquefaciens and Aeromonas hydrophila. The same effect was observed by Ran et al. (2012) in Ictalurus punctatus against A. hydrophila and Edwardsiella ictaluri. Das et al. (2013) observed an increase in disease resistance in Catla catla. The aim of this study was to evaluate the effect of diet containing three concentrations of the probiotic B. amyloliquefaciens on performance, blood profile and intestinal morphology in Nile tilapia, O. niloticus, reared in cages. MATERIALS AND METHODS Fish culture, diet and feeding Masculinized Nile tilapia (Oreochromis niloticus) (35 ± 5 g) from the same spawning were obtained from commercial breeding. The cages (1.5 m3) were distri- buted in four experimental groups (triplicate) in a completely randomized design (78 fish per cage). The experiment was conducted in the reservoir 3 of the Aquaculture Center of Sao Paulo State University, Jaboticabal (21°14.33'S, 48°17.55'W) in April-June 2014. This reservoir has approximately 10,000 surface m2. The animals were acclimated for 10 days and fed with basal diet (pellets used in this experiment without addition of probiotics). It was used the program “Super Crac Premium” to formulate the diet according the suggestions of Furuya (2010). Feed was extruded. The feed rate was 3% of body weight, 3 times a day for 90 days on basal diets containing 0 (control); 1×106 CFU g-1; 5×106 CFU g-1; and 1×107 CFU g-1 of Bacillus amyloliquefaciens. Diet composition is shown in Table 1. To achieve homogeneous final concentrations of bacteria in the diet and to facilitate the adhesion of the probiotic, the bacterial suspension was added and homogenized manually with commercial vegetable oil (4% by weight; 4.000 kcal L-1). Thus, according to the recommendations of Das et al. (2013) food was prepared every 7 days to maintain optimal probiotic levels. Fish were measured at 30 and 60 days for diet amount adjustment. During the experimental period, except temperature, there were no important changes in the water quality that could have interfered in the experiment results (Boyd & Massaut, 1999). The values were maintained as follows: the water temperature varied from 27.1 to 21.9°C (24.35 ± 2.43°C) and dissolved oxygen (7.31 ± 0.48 mg L-1). Both were measured using an YSI 53 device (YSI Company, USA); pH (7.50 ± 0.30) and electrical conductivity (45.54 ± 10.40 µV) were measured using a 63 YSI device (YSI Company, USA). Water transparency (26.03 ± 2.10 cm) was measured using the Secchi disk at 11:00 h on alternate days. Isolation and identification of the probiotic bacterial strain The bacterium was isolated from a commercial product containing Bacillus amyloliquefaciens. To confirm the presence of the bacteria in the product, 1.0 g of the probiotic was homogenized in 99 mL of phosphate buffered saline (145 mM NaCl, 1.4 mM NaH 2PO4, 8 mM Na2HPO4, pH 7.4). Thus, it was performed serial dilutions with peptone solution (4%) (Sigma-Aldrich, USA), distributed into Petri dishes containing culture medium trypticase soy Agar (TSA), and incubated for 48 h under aerobic conditions at 26°C. Colonies of Bacillus sp. were identified according their morphological, biochemical and dyeing features (Priest et al., Dietary B. amyloliquefaciens in cage-reared tilapia Table 1. Ingredients and proximal composition of the basal diet. Ingredients Corn flour Soybean meal (38% CP) Rice bran Wheat flour Corn gluten (20% CP) Poultry by-product meal (65% CP) Fish meal (60% CP) DL-Methionine Dicalcium phosphate L-Tryptophan L-Lysine Antifungi Antioxidant Vitamin mix¹ Proximal composition (%) Dry matter Crude protein Digestible energy (kcal kgˉ¹) Ether extract Fiber Ash % 30.000 20.000 14.766 13.000 12.000 5.000 3.000 0.700 0.610 0.200 0.164 0.030 0.030 0.500 90.10 30.21 2990.12 4.98 4.67 4.78 ¹Composition of vitamin-mineral supplement (Fri-Ribe): vitamin A, 600,000 IU; Vitamin D3 600,000 IU; Vitamin E 12,000 IU; Vitamin K3, 1200 mg; vitamin B1, 1200 mg; vitamin B2, 1536 mg; vitamin B6, 1287 mg; B12, 4000 mg; folic acid, 198 mg; pantothenic acid, 3800 mg; Vitamin C, 48,000 mg; biotin, 20 mg; choline, 30,000 mg; niacin 19,800 mg; Fe, 25,714 mg; Cu, 1960 mg; Mn, 13,334 mg; Zn, 6000 mg; I, 948 mg; Co, 2 mg; Se, 30.10 mg. 1987). The sequencing of 16S rDNA gene was performed from isolated colonies by the method of Sanger et al. (1977). The quantification of the probiotic bacteria in the feed was performed by homogenizing 1.0 g of diet in 99 mL of PBS. Then, it was performed serial dilutions as described above. Finally, they were evaluated the colonies that showed morphological, biochemical, and dyeing features compatible with B. amyloliquefaciens. Samples of all treatments were subjected to molecular identification of the bacterium as described previously. Growth performance After 90 days, fish were measured and weighed to determinate performance indices: Weight gain (WG) = Final weight - initial weight Specific growth rate (SGR) = (In[final weight] In[initial weight]) x 100/number of days 965 Feed efficiency (FE) = weight gain x 100/food consumed Proximal composition After the feeding period, 10 fish from each group were euthanized using benzocaine (0.5 g L-1) (Wedemeyer, 1970) and stored at -18°C for later analysis of proximal composition. Then the samples were ground to obtain a homogenous product and dried in an oven at 55°C for 48 h. The humidity was determined by drying in an oven at 105°C for 24 h. The ash content was obtained after incineration in a muffle furnace at 550°C and the energy by bomb calorimetry. Protein was determined by Kjeldahl method and the ether extract by Soxhlet method (AOAC, 2005). Hematological profile and glucose After anesthesia, blood of 10 fish per replicate were collected by puncture of the caudal vessel and distributed in tubes containing EDTA (10%) for determination of hematocrit (Goldenfarb et al., 1971), hemoglobin (Collier, 1944) and, red blood cell counts using the solution Natt & Herrick as diluent and dye. Then, they were calculated the mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and, mean corpuscular hemoglobin concentration (MCHC). Blood smears were stained with Panotic dye (Laborclin, PR, Brazil) to count leukocytes and thrombocytes. The determination of blood glucose was performed with the rapid glucose analyzer One Touch UltraMini® (Lifescan, CA, USA). Analysis of intestinal morphometry The collection of the intestine was performed in the same fish used in the blood analysis. After deep anesthesia, it was performed a longitudinal incision in the abdomen and collected a fragment of the anterior portion of the intestine located two centimeters after the pylorus. The fragments were fixed in Bouin solution for 24 h. Then, they were dehydrated in 70% alcohol to histological processing (Honorato et al., 2011). The slides were stained with hematoxylin-eosin (HE) for morphometric evaluation of villi and with periodic acid-Schiff (PAS) for goblet cell count. The measurement of the height and width of the villi, epithelial thickness, and counting of goblet cells were performed according to Mello et al. (2013). It was used a Zeiss Axio Vision image analyzer. Statistical analysis Data were subjected to analysis of variance (ANOVA), differences between treatments were compared by Tukey 966 Latin American Journal of Aquatic Research test (P < 0.05). Data were analyzed by statistic R software (version 0.98.1) and presented as mean ± standard deviation. number of goblet cells comparing to control group (Table 6, Fig. 2). DISCUSSION RESULTS Performance and proximal composition Under the conditions evaluated, there was no statistical difference in weight gain, feed conversion, specific growth rate, and feed efficiency (Table 2). Proximal analysis of fish carcass showed no significant difference between treatment and control groups (Table 3). Hemoglobin and glucose levels showed differences between treatments. The group supplemented with the highest concentration of probiotic (1×107 UFC g-1) showed the lower values for these variables. Other red blood cell parameters (Table 4) and differential leukocyte count (Table 5) showed no statistical difference between treatments. Intestinal morphometry Histomorphometric evaluation of the anterior portion of the intestine showed significant difference in the height of the villi in groups supplemented with 5×106 CFU g-1 and 1×107 CFU g-1 compared to 1×106 CFU g1 and control groups (Fig. 1). There were observed no lesion in the intestine and no differences in the width and thickness of the villi between control and treatment groups (Table 6). Fish that received the highest concentration of probiotic also had significantly greater The use of B. amyloliquefaciens as a probiotic in fish feeding is recent and information is scarce. However, it has demonstrated that dietary supplementation with this bacterium improves growth performance in fish. In tilapia fingerlings reared in glass aquaria, supplementation with this bacterium improved weight gain, specific growth rate and feed conversion after supplement with 10 6 CFU g-1 of B. amyloliquifaciens for 60 days (Reda & Selim, 2015). However, no differences were observed when the probiotic was administered at 104 CFU g-1 of concentration. Similarly, Telli et al. (2014) found no effect of Bacillus subtilis (5×106 CFU g-1) on performance of Nile tilapia, even after 84 days of feeding supplemented diet. In this study, there was no effect of the probiotic B. amyloliquefaciens on growth performance. This can be explained due to the low temperatures in the last 2 months. Marcusso et al. (2015) reported that the homeostasis of Nile tilapia rearing at temperatures below 24ºC could be affected, enhancing the susceptibility to bacterial infections and impairing the growth performance. Ridha & Azad (2012) tested B. amyloliquefaciens (108 CFU g-1) in Nile tilapia reared in tanks for 99 days and did not find any difference in performance indices either. However, they observed 60 days after that fish Table 2. Growth performance indices of Nile tilapia fed with experimental diets. WG: weight gain, SGR: specific growth rate, FE: feed efficiency. Mean ± SD. There were no statistical differences (P > 0.05) between treatments. Treatments Control 1×106 UFC g-1 5×106 UFC g-1 1×107 UFC g-1 WG (g) SGR (%) FE 86.84 ± 36.53 83.47 ± 30.84 90.44 ± 39.68 94.5 ± 39.66 1.10 ± 0.51 1.09 ± 0.44 1.13 ± 0.53 1.18 ± 0.55 0.842 ± 0.245 0.864 ± 0.245 0.791 ± 0.300 0.906 ± 0.206 Table 3. Body composition (%) and gross energy (kcal kg-1) of Nile tilapia fed with experimental diets. CP: crude protein, EE: ether extract, M: moisture, Ash; GE: gross energy. Mean ± SD. There were no statistical differences (P > 0.05) between treatments. Values are in % of dry weight. Treatments Control 1×106 UFC g-1 5×106 UFC g-1 1×107 UFCg-1 CP% EE % M% Ash % GE (kcal kg-1) 43.1 ± 0.3 44.6 ± 0.4 39.9 ± 0.6 42.8 ± 0.4 25.8 ± 0.8 24.2 ± 0.9 25.4 ± 0.7 26.6 ± 0.8 77.5 ± 0.5 76.2 ± 0.3 76.8 ± 0.6 77.3 ± 0.5 11.8 ± 0.7ª 13.8 ± 0.4ª 12.3 ± 0.4ª 12.0 ± 0.6ª 5064 ± 21.1 5716 ± 13.5 5150 ± 16.1 5635 ± 18.3 Dietary B. amyloliquefaciens in cage-reared tilapia 967 Table 4. Hematological parameters. Hct: hematocrit, Hb: hemoglobin, RBC: red blood cells, MCHC: mean corpuscular hemoglobin concentration, MCH: mean corpuscular hemoglobin, MCV mean corpuscular volume, and G: plasma glucose of the Nile tilapia fed different probiotic concentrations in feed. Means ± SD. Values (mean ± SD) with different letter are significantly different (P < 0.05). Treatment Control 1×106 UFC g-1 5×106 UFC g-1 1×107 UFC g-1 Hct (%) 36.8 ± 2.9ª 38.5 ± 3.4ª 39.2 ± 1.6ª 37.4 ± 1.9a Hb (g dL-1) RBC (104 µL-1) a 10.75 ± 1.0 11.20 ± 1.6ª 10.90 ± 1.3ª 8.53 ± 1.2b 295.93 ± 49.6ª 292.33 ± 34.6ª 303.06 ± 33.4ª 293.50 ± 36.5ª MCHC (g dL-1) 27.01 ± 3.4ª 24.44 ± 3.2ª 27.95 ± 4.9ª 26.36 ± 4.6ª MCH (pg) a 33.05 ± 5.8 32.53 ± 4.6a 35.72 ± 7.0a 35.08 ± 7.9a MCV (fL) G (mg dL-1) 125.96 ± 21.7ª 123.78 ± 11.0a 127.89 ± 11.8ª 133.31 ± 20.4ª 110.00 ± 34.9ª 66.80 ± 36.8ab 41.40 ± 9.8b 36.25 ± 5.8b Table 5. Differential leukocyte count in the circulating blood of Nile tilapia fed the experimental diets. Means ± SD. There were no statistical differences (P > 0.05) between treatments. Treatment Control 1×106 UFC g-1 5×106 UFC g-1 1×107 UFC g-1 Leukocyte (mm3) 110.2 ± 20.5 129.4 ± 27.8 105.92 ± 14.3 112 ± 13.4 Lymphocytes (103 µL-1) 31.44 ± 8.1 26. 31 ± 13 30. 72 ± 9.3 28.11 ± 6.4 Neutrophils (103 µL-1) 16.3 ± 4.92 19.55 ± 5.21 16.2 ± 4.16 14.11 ± 3.1 Monocytes (103 µL-1) 16.02 ± 3.4 15.03 ± 4.7 17.46 ± 6.2 14.6 ± 7.2 Basophils (103 µL-1) 0±0 0±0 0±0 0±0 Eosinophils (103 µL-1) 0.3 ± 0.04 0.31 ± 0.2 0.27 ± 0.18 0.32 ± 0.23 Figure 1. Comparative photomicrographs of the anterior portion of the intestine of Nile tilapia fed different probiotic concentrations in the diet. a) Control group, b) 1×106 CFU g-1, c) 5×106 CFU g-1, and d) 1×107 CFU g-1. Villi height enhanced proportionally to the concentration of the probiotic. Scale bar: 200 µm. Stain: hematoxylin-eosin. 968 Latin American Journal of Aquatic Research Figure 2. Comparative photomicrographs of the epithelial layer of the intestinal villi of Nile tilapia supplemented with different probiotic concentrations in the diet. a) Control group, b) 1×106 CFU g-1, c) 5×106 CFU g-1, and d) 1×107 CFU g-1. Goblet cells (deep red colour -magentacells on the edge of the villi) increased proportionally to the concentration of the probiotic in the diet. Scale bar: 100 µm. Stain: Periodic acid-Schiff (PAS). previously supplemented with the bacterium showed better growth performance than control group, suggesting that the effects of this probiotic occur over time. Unlike this report, in the present study fish were reared in cages in a reservoir with abundant algae (low transparency of water). This availability of food could influence the growth performance of fish, explaining why there was no difference between treatments. The efficiency of nutrient transfer from food to the organism can be measured by the proximal composition analysis. This is of great importance due to it may reflect the nutritional value of the fish and its organoleptic characteristics (Contreras, 1994). Several authors have reported improvements in body composition of Nile tilapia supplemented with probiotics (Mello et al., 2013; Hassaan et al., 2014; Reda & Selin, 2015). However, in this study, body composition analysis values showed no significant difference between treatment and control groups. Similar results were found by Telli et al., (2014) in Nile tilapia fed diet supplemented with B. subitilis. Hematological variables are commonly used as indicators of physiological condition in fish (Mohapatra et al., 2014). Some studies reported that after feeding with Bacillus sp., Nile tilapia presented alterations on the hematological variables (Hassaan et al., 2014; Telli et al., 2014.) or not (Kumar et al., 2006; Soltan & El-Laithy, 2008). In the present study, we did not observe differences in hematocrit, red blood cells count and hematological indices (MCHC, MCH and MCV). However, there was a higher hemoglobin levels in the fish fed with lower concentrations of probiotic. This could be related to the necessity of transport more oxygen in blood to meet the increasing energy demand of fish promoted by high levels of glucose (Nikinmaa et al., 1983). As in current study, Reda & Selim (2015) observed increase in hemoglobin levels in blood of Nile tilapia supplemented with B. amyloliquefaciens. However, the authors also observed an increase in the number of erythrocytes and leukocytes in blood, but without changes in blood glucose. They were reporter that probiotic bacteria enhance the iron absorption due to the release of organics acids in the gut. This would increase the availability of iron to produce hemoglobin in rats (Yadav et al., 2007) and fish (Dahiya et al., 2012). Probiotics enhance fish tolerance to stress agents of environmental origin or related to handling (TapiaPaniagua et al., 2014). During stress, the release of catecholamines stimulates glycogenolysis (MartínezPorchas et al., 2009). The rapid increase of glucose in blood is one indicator of stress in fish (Simoes et al., 2012). In the present study, the higher blood glucose observed in the control group compared to supplemented ones with the greater inclusion of probiotic in the diet may reflect the homeostatic state of the animals against adverse conditions. B. amyloliquefaciens seems to have positively influenced the glucose levels of fish supplemented with 5×106 CFU g-1 and 1×107 CFU g-1 of feed, enhancing the homeostatic state of fish. Similar findings have been reported by Mohapatra et al. (2014) in Labeo rohita stressed that presented lower glucose levels in fish fed with this probiotic. Dietary B. amyloliquefaciens in cage-reared tilapia 969 Table 6. Histomorphometric parameters and goblet cells per villus in the intestine of Nile tilapia fed the experimental diets. Mean ± SD. Values (mean ± SD) with different letter are significantly different (P < 0.05). Treatments Control 1×106 UFC g-1 5×106 UFC g-1 1×107 UFC g-1 Total height of villi (µm) 466.0 ± 92.9a 407.2 ± 121.1a 438.4 ± 105.5a 487.2 ± 31.2a Height of villi (µm) 378.1 ± 99.7b 371.3 ± 91.6b 423.2 ± 95.3a 469.4 ± 25.1a Stress is one of the factors that contribute to the emergence of primary diseases and mortality of reared fish. Both food and environmental changes could promote stress modifying the gut microbiota and the establishment of pathogens in the gastrointestinal tract (Tannock & Savage, 1974). Thus, it is likely that an improvement in the homeostatic level promoted by the probiotic in this study may be related to increased stability of the gut microbiota with reduction of harmful bacteria in the epithelium (Rollo et al., 2006). The intestinal lumen of the fish is lined by a simple columnar epithelium interspersed with goblet cells (Reifel & Travill, 1979). The integrity of the intestinal mucosa is a consequence of the intensity of epithelial cell renewal that determines the uniformity of the villi and the number of goblet cells (Mello et al., 2013). The increased villi height observed in the supplemented groups in this study and the lower number of pathogenic bacteria in the enterocytes could be related to the increased availability of nutrients and reduced desquamation of the epithelium. Furthermore, it is known that some proteins produced by probiotic bacteria promote increased cellular survival time of the intestinal tract due to the inhibition of apoptosis signaling induced by cytokines (Sherman et al., 2009). Mello et al. (2013) observed in Nile tilapia fed diets containing Bacillus cereus and B. subtilis an increasing of the area of absorption, nutrient retention and consequent improvement in growth performance and body composition. In this study, although the intestinal absorption area has grown substantially, there was no difference in performance. This can be explained due to the short evaluation time, which was not enough to show its effects in performance and proximal analysis. It can also relate to the low concentration of the probiotic or due to the adverse weather conditions recorded in the last month of the experiment in which the temperature decreased. The production of mucus by goblet cells is an important mechanism of protection against the entry of pathogens through the intestinal tract (Ellis, 2001). Furthermore, the mucus has bactericidal effect, protects Width of villi (µm) 62.5 ± 27.7a 51.4 ± 8.7a 54.2 ± 11.4a 57.0 ± 13.3a Epithelium thickness (µm) 113.3 ± 83.4a 98.9 ± 19.8a 118.3 ± 21.5a 107.3 ± 23.9a Goblet cell count per villi 11.38 ± 5.2b 16.45 ± 6.63ab 25.24 ± 8.32a 23.32 ± 8.43a against toxic substances and aids the transport between the luminal contents and epithelial cells (Smirnov et al., 2005). It is well documented that probiotics stimulate the development of goblet cells in the intestine (Nayak, 2010; Mello et al., 2013). In this study, fish that received the highest level of inclusion of probiotic showed significantly higher number of goblet cells compared to control group. This result corroborates the observations of Reda & Selim (2015) that observed growth of the villi and increased goblet cell number in fish supplemented with B. amyloliquefaciens. 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Hu, Y-L. Zhang & S-K. Li. 2014. Enhancement of the immune response and protection against Vibrio parahaemolyticus by indigenous probiotic Bacillus strains in mud crab (Scylla paramamosain). Fish Shellfish Immunol., 41: 156162. Yadav H., J. Shalini & P.R. Sinha. 2007. Antidiabetic effect of probiotic dahi containing Lactobacillus acidophilus and Lactobacillus casei in high fructose fed rats. Nutrition, 23: 62-68. Ziaei-Nejad, S., M. Rezaei, G. Takami, D. Lovett, A. Mirvaghefi & M. Shakouri. 2006. The effect of Bacillus spp. bacteria used as probiotics on digestive enzyme activity, survival and growth in the Indian white shrimp Fenneropenaeus indicus. Aquaculture, 252: 516-524. Lat. Am. J. Aquat. Res., 43(5): 972-985, 2015 DOI: 10.3856/vol43-issue5-fulltext-17 Oceanic and climatic drivers of mangrove changes Research Article Oceanic and climatic drivers of mangrove changes in the Gulf of Urabá, Colombian Caribbean July A. Suárez1*, Ligia E. Urrego2*, Andrés Osorio1* & Hiara Y. Ruiz2 *Oceanography and Coastal Engineering Research Group (OCEANICOS) 1 Universidad Nacional de Colombia, Sede Medellín, Escuela de Geociencias Facultad de Minas AA, 569 Medellín, Calle 59A Nº 63-20. Medellín, Colombia 2 Universidad Nacional de Colombia, Sede Medellín. Departamento de Ciencias Forestales Colombia Núcleo El Volador AA 569 Medellín, Colombia Corresponding author: July A. Suárez ([email protected]) ABSTRACT. The Gulf of Uraba is the largest estuary on the Caribbean coast of Colombia. The aim of this research was to analyse the oceanic, climatic and environmental variables that influence mangrove structure and composition in the gulf. Based on the availability of remote sensing, the study area was divided into western and eastern zones. The spatial pattern of environmental variables (water salinity, pH and percentage of organic matter, sand, silt and clay in the soils) and oceanic and climatic variables (winds, wave height and wave period) was analysed. The relationship of these variables with variables of vegetation structure (basal area, diameter at breast height, tree height, and abundance of seedlings of mangrove species in 1 m2 subplots) was analysed in 27 plots of 500 m2 containing fringe mangroves and 5 plots containing basin mangroves. Mangroves of the western zone showed a higher structural development and were dominated by Rhizophora mangle (red mangrove). This zone is supplied by fresh water and sediments, and the soils have a high content of organic matter and clay and a low degree of anthropogenic disturbance. The eastern zone was characterized by higher pore water salinity due to lower freshwater input from rivers. In this area there is a smaller impact of waves and winds, higher sedimentation rates, high anthropogenic disturbance and mangroves are dominated by Avicennia germinans (black mangrove). Although Laguncularia racemosa (white mangrove) did not show a particular spatial pattern, due to its tolerance to open canopy conditions it was commonly found in anthropogenically disturbed areas. Keywords: coastal ecosystems, swell, winds, coastal erosion, sediment transport, river flow, Colombian Caribbean. Controladores oceánicos y climáticos de cambios en los manglares en el Golfo de Urabá, Caribe colombiano RESUMEN. El Golfo de Urabá es el mayor estuario en la costa caribe de Colombia. El objetivo de esta investigación fue analizar las variables oceánicas, climáticas y ambientales que influyen en la estructura y composición de los manglares en el golfo. Según la disponibilidad de información de sensores remotos, el área de estudio se dividió en una zona occidental y otra oriental. Se analizó el patrón espacial de las variables ambientales (salinidad del agua, pH y porcentaje de materia orgánica, arena, limo y arcilla en los suelos) y las variables oceánicas y climáticas (vientos, altura y período del oleaje). Se analizó la relación de estas variables con las variables estructurales de la vegetación (área basal, diámetro a la altura del pecho, altura de los árboles y abundancia de plántulas de especies de manglar en sub-parcelas de 1 m2), en 27 parcelas de 500 m2 que contienen manglares de borde y 5 parcelas que contienen manglares de cuenca. Los manglares de la zona occidental mostraron un desarrollo estructural superior y fueron dominados por Rhizophora mangle (mangle rojo). Esta zona recibe gran cantidad de agua dulce y sedimentos, y los suelos tienen alto contenido de materia orgánica y arcilla, y bajo grado de perturbación antrópica. La zona oriental se caracteriza por mayor salinidad del agua debido a una menor entrada de agua dulce de los ríos. En esta zona se presenta un menor impacto de oleaje y vientos, altas tasas de sedimentación, alta perturbación antrópica y los manglares están dominados por Avicennia germinans (mangle negro). Aunque Laguncularia racemosa (mangle blanco) no mostró un patrón __________________ Corresponding editor: Ricardo Prego 972 1 973 2 Latin American Journal of Aquatic Research espacial particular, debido a su tolerancia a las condiciones abiertas de dosel, se encuentra comúnmente en áreas con mayor intervención antrópica. Palabras clave: ecosistemas costeros, mar de fondo, viento, erosión costera, transporte de sedimentos, caudal del río, Caribe colombiano. INTRODUCTION Mangroves are important ecosystems for human communities not only because of their economic benefit but also because they protect coasts from tsunamis, storm surges and erosion (Mazda et al., 1997; Alongi, 2008). In addition, they reduce coastal water eutrophization, contribute to sediment and human waste uptake and play an important role in organic matter exchange, carbon assimilation and faunal feeding and reproduction (Ewel et al., 1998; Alongi, 2008). Since they are restricted to the ocean-continent ecotone and catch high fluvial water and sediment loads, mangroves structure, floristic composition and natural regeneration of mangrove vegetation are determined by several biotic, abiotic and anthropogenic drivers, and are vulnerable to global and regional environmental and climatic changes. Regional climate change, especially that related to precipitation patterns, the flooding of rivers, rises in sea level and ocean circulation patterns (Duke et al., 1998; Gilman et al., 2008) may influence mangrove distribution and dynamics. Local drivers, such as the magnitude and direction of winds, geomorphology, pore water salinity, and soil conditions also play an important role in vegetation patterns (Krauss et al., 2006). Tidal range and amplitude, and sea level rise may affect the distribution of mangroves, depending of the rate of fluvial sediment supply. If the rate of sea level rise is higher than sediment input, coastal erosion occurs and the mangroves may disappear (Parkinson et al., 1994), but if the rate of sediment supply exceeds the increase in sea level rise, mangroves may colonize on prograding deltas and beaches (Gilman et al., 2008; Perillo et al., 2009; Shearman, 2010) or may even be replaced by upland forests. Despite the low tides on the Colombian Caribbean coast (0.40 m), a decreasing west-eastern gradient in rainfall drives deterioration in the mangrove vegetation structure. In the Gulf of Urabá, located at the Colombian Caribbean coast, higher mean annual precipitation (2,500 mm), means that mangrove forests can reach 9 m average height and contain about 10 tree species (Urrego et al., 2014). In contrast, in La Guajira in the north-eastern extreme of the country, significantly drier conditions (mean annual precipitation 500-1000 mm) mean that trees reach only 5 m in average height and no more than three true mangrove species are found (Ulloa-Delgado et al., 1998). Along the coast of the Gulf of Urabá, where there are more than 4500 ha of mangroves, structural, floristic and environmental differences have also been identified (Urrego et al., 2014). In these forests, flooding, pore water salinity and sediment input are responsible for differences in physiographical mangrove types (GarcíaValencia, 2007; Hoyos et al., 2012; Molina et al., 2014; Urrego et al., 2014). In addition, large temporal changes in mangrove forest expanses and composition recorded in the Caribbean have been related to coastal erosion and accretion processes (Torres et al., 2008; Rangel et al., 2012), as have extreme events like hurricanes (OrtizRoyero, 2012) and storm surges as well as anthropogenic disturbances (Urrego et al., 2014). In fact, between 2004 and 2011, 16% of the Colombian Caribbean mangroves were lost due to both causes (Rangel et al., 2012). Despite the current sea level rise (Torres et al., 2008) in the Colombian Caribbean, mangrove colonization has taken place along river deltas and beaches that receive high fluvial sediment input (Parkinson et al., 1994; Urrego et al., 2014). Nevertheless, it is not clear how important drivers such as winds, marine currents and sediment dynamics are associated to both coastal geomorphology and mangrove distribution and dynamics (Posada, 2011). However, neither the sedimentation-erosion processes that are closely linked to wave dynamics in the gulf (Molina et al., 2014), nor sea level changes and sediment transport and dispersion have as yet been related to mangrove vegetation (García-Valencia, 2007). As a first approach, we propose the hypothesis that besides continental processes related to geomorphology, the force of winds and waves and their influence on sediment composition and dynamics (sedimentation and erosion) play an important role in the structure, composition and dynamics of mangroves in the Gulf of Urabá. This is in spite of the gulf’s pocket shape that could homogenize marine conditions and their influence on vegetation. MATERIALS AND METHODS Study area The Gulf of Urabá is located in the northwestern corner of the Colombian Caribbean (Fig. 1). The study area covers 10,461 ha, of which 2,874 ha were covered with Oceanic and climatic drivers of mangrove changes 9743 Figure 1. Location of the study area showing the two zones, the sampling sites and the main vegetation types found in the Gulf of Urabá. mangrove forests in 2009. Other vegetation types present are tropical rain forests and open vegetation (grasslands). Water bodies and urban constructions are also present in the area. Based on the availability and dates of remote sensing (satellite images and aerial photographs), the study area was divided into two zones: the western zone that includes the Atrato River delta, and the eastern zone that includes the mouths of the Turbo and Currulao rivers (Fig. 1). In the gulf, the mean annual precipitation is 2,500 mm. The mean monthly precipitation is 250 mm during the rainy season (from May to November) and 100 mm during the dry season (From December to April). The mean annual temperature is 27°C (CIOH, 2010) and the greatest variation (26-28oC) occurs during the day time (Francois et al., 2007). According to the Holdridge classification system it is a typical tropical rainforest climate (Espinal, 1990). The Intertropical Convergence Zone (ITCZ) modulates the annual rain fall distribution in the gulf. During the dry season, when the ITCZ is farthest from the gulf, winds come from a north-easterly direction. The circulation currents present in these winds are persistently high speed and are characterized by dry atmospheric stability, low levels of cloud and precipitation, and low atmospheric humidity (Francois et al., 2007). The Gulf of Urabá is a pocket shaped water body located near the Caribbean border between Panamá and Colombia. While the northern part of the gulf is wider 4975 Latin American Journal of Aquatic Research and west-east oriented, the southern part is semi-closed and north-south oriented. The length of the gulf from north to south is approximately 80 km, and the average width is 25 km. The microtidal regime is mixed semidiurnal with an average maximum height between 0.30 and 0.92 m. While the deepest waters (80 m) are found towards the northern part of the gulf the shallowest ones (30 m) are concentrated towards the southern area (Bernal et al., 2005a; Montoya & Toro, 2006; Francois et al., 2007). The winds enter the gulf seasonally from several directions and at different speeds. While during the wet season the south-west winds had a speed between 1.5 and 2.7 m s-1, during the dry season the north to northeasterly winds reached speeds of 3-4 m s-1 with maximum of 10 m s-1 (Francois et al., 2007). From a hydrodynamic perspective, wave modelling data that included both average and extreme conditions validated with wave sensors identified two areas dominated by different types of waves in the gulf (Osorio et al., 2010). The first area is located to the north of the boundary between the Atrato and Turbo rivers deltas and the offshore limit of the gulf. The second is located towards the south between the aforementioned deltas and the end of the gulf in the Bahia Colombia. While the first area was strongly dominated by swell waves (waves coming from deep water), the second area was strongly dominated by sea waves (waves generated by local winds). Deep surge energy is dissipated while propagating landwards into the gulf and especially near the mouth of the Atrato River (Molina et al., 2014). Our main study area is located in the south (see the eastern and south-western zone in Fig. 1). The Atrato River is the main source of freshwater and sediments to the gulf. The river flow distribution is synchronous with that of precipitation. The multiannual mean runoff flow of the river is 2372 m3 s-1 (Francois et al., 2007; Posada, 2011). The coastal erosion- sedimentation pattern is spatially variable along the gulf’s shores. Strong erosion processes have been recorded in the eastern zone as a result of the Turbo River being artificially diverted in 1954. On the other hand, the western zone is dominated by the highly dynamic Atrato River delta. In this area both erosion processes and the deposition and accumulation of sediments take place (Bernal et al., 2005b; Francois et al., 2007). Six percent of Colombian Caribbean mangroves are found along the coasts of the Gulf of Uraba (INVEMAR, 2012). In the tidal flooded zones and swamps, two physiographic mangrove types are present: fringe mangroves dominated by R. mangle and basin mangroves dominated by A. germinans. In alluvial flooded zones that are not heavily influenced by the tide, other mangrove species such as Conocarpus erectus (button mangrove) and Pelliciera rhizophorae (tea mangrove), and transitional tropical rain forest species such as Montrichardia arborescens (yautia madera), Raphia taedigera (yolillo palm), Pterocarpus officinalis (corkwood) and Margaritaria nobilis (bastard hogberry) are commonly found (Sánchez et al., 1997; Urrego et al., 2014). Space-time analysis of mangroves Oceanic and climate variables such as wave height (Hs) and peak period (Tp) of the mean regime, modelled by Molina et al. (2014), were included in our analysis. For the analysis of oceanic and climatic variables, only data values obtained during the rainy season were available. The sediment dynamics in each plot were included as nominal variables in accordance with the classification of Bernal et al. (2005b) (erosion: 1, sedimentation: 100 and stability: 50). The analysis of forest structure and floristic composition was based on field data from 32 plots each of 500 m2, mostly located 100 m landwards along the coasts at both sides of the gulf. At each plot, the diameter at breast height (DBH), mean tree height and basal area of all trees with DBH >2.5 cm were measured. Values of pH and the percentages of sand, silt, clay and organic matter in surface soil samples, as well as the salinity and pH of pore water, were also measured during the rainy season and included in the analysis as environmental variables of each plot. Temporal mangrove extension changes in the gulf were based on analysis of aerial photographs and were used for correlations with oceanic and climatic features. While changes in vegetation cover in the western zone were analysed between 1975 and 2009, in the eastern zone they were assessed between 1980 and 2009. Gains and losses in expanses of fringe, riverine and disturbed mangroves were analysed. Net gain occurred when non-mangrove coastal vegetation such as tropical rain forest and herbaceous vegetation, or bare soil zones, water bodies (sea, rivers, lakes and lagoons) and urbanized areas, were converted into mangroves. Net losses occurred when mangroves shifted into any one of the aforementioned areas. The anthropogenic influence on vegetation structure was assessed by measuring the distance between each plot to the closest human settlement (the city of Turbo in the eastern zone and the Bocas de Atrato Village on the western side), since such a distance influences the feasibility of humane displacement to mangroves for harvesting. Mangrove sedimentation rates were obtained from two sediment cores of 50 and 60 cm deep, retrieved using a Mackauley corer (Traverse, 1988). The first in Oceanic and climatic drivers of mangrove changes El Uno Bay (eastern zone) and the second in The Candelaria Bay (western zone). In order to estimate the chronology, isotopic analysis with 210Pb was achieved at My Core Scientific Inc., Laboratory (Dunrobin, Ontario, Canada) Based on environmental variables recorded at each plot, the spatial variation of the percentages of sand and organic matter in the soil, the magnitude of the winds and coastal sediment dynamics (sedimentation or erosion) in the study area were assessed using trend analysis with Arcgis 9.3 software (ESRI. Inc., 9.3). After performing the Kolmogorov-Smirnov normality test using Statgraphics Centurion XV software (Statpoint, 2005), vegetation, hydrodynamics and climatic variables were normalized by means of the function log(x) + 6, where x is equal to a variable value and 6 was added to eliminate the negative values. In order to establish the relationship between vegetation and environmental, climatic and oceanic variables, and to look for spatial differences in mangrove vegetation patterns, Principal Component Analysis (PCA) and Redundancy Analysis (RAD) were performed using Canoco 4.5 (Ter Braak & Smilauer, 2002). The relative weight of each of the oceanic, environmental and anthropogenic variables was established through multiple regression analysis. RESULTS Spatial analysis of hydrodynamic and vegetation variables Mangrove extension changes based on analysis of aerial photographs, were correlated with oceanic and climatic features and show the impact of oceanic and environmental variables on the spatial distribution of the mangrove species. Winds from south-western with mean speed between 1.5 and 2.7 m s -1 were included in the analysis. The areas sheltered from winds were located mainly inside the bays of the western gulf. However, the effects of waves (Hs and Tp) on vegetation structure were spatially heterogeneous. Even though some areas were sheltered, they were highly influenced by waves (Hs of 0.17 and 0.22 m and Tp between 2.4 and 2.8 s). Along most of the coasts, especially in the bays, the magnitude of waves was lower (Hs of 0.1 m and Tp between 1.5 and 2 s) in both seasons and its effect on vegetation structure was also softer since it was protected from the direct action of waves (Fig. 2). In the study area, sea waves predominated (Hs decreased to about 0.1-0.4 m) due to the dissipation of swell energy, especially when they approached the Atrato River delta. However, the north-westerly waves 9765 were influenced by swell waves, where the waves reached up to 1.2 m in the dry season and affect the fringe mangroves. In contrast, the lowest Hs were recorded along the internal bays of the Atrato River delta in the west (Hs of 0.1 m and wave periods of 1.5 to 2 s), which were sheltered from the direct impact of winds and waves, and where both fringe and basin mangroves were found. At the eastern, along the prograding zone of the spits of the rivers, where the waves reached up to 0.5 m in some areas, mangroves were influenced the least by the waves. Regarding environmental variables (Fig. 3), mangroves in the western zone of the gulf were characterized by low values of water salinity (nearly 0) and pH (average 3.8), but high percentages of organic matter (30-50%) and clays (20-65%) in the soils. The high flow of the Atrato and León rivers diminished the pore water salinity and the impact of wave energy on fringe mangroves and tropical rain forests that were highly influenced by the sediment loads of these rivers. In contrast, the mangrove stands of the eastern zone showed higher values of pH (7.1-7.5), higher percentages (100% in basin mangroves and 0-18% in fringes) of sand in the soils, and greater pore water salinity (13.8-20.8). The relationship between oceanic, environmental and anthropogenic variables and the structure and composition of mangrove vegetation was evaluated by multiple regression analysis and is shown in Table 1. A strong relationship was found regarding the structure of the three main mangrove species. While the averaged DBH and basal area of R. mangle and A. germinans adult trees increased with distance to human settlements, the abundance of seedlings and saplings declined in the first species but increased in the second. On the other hand, the averaged DBH and basal area of saplings and small trees of L. racemosa showed an inverse relationship with distance to human settlements. Therefore, distance from mangroves to human settlements better explained the variability in the structure of L. racemosa than other variables (Hs, pore water salinity and river flow). The averaged DBH (of trees with DBH >10 cm) of A. germinans showed a stronger relationship with distance from human settlements than with the soil pH and percentage of clay. The seedling abundance was also more strongly related to this distance than pore water salinity and river flow. However, when the averaged DBH of saplings and small trees (DBH <10 cm) were the dependent variables, the negative relationship was stronger than previously important variables such as the percentage of sand in the soil, wind speed and Hs. 977 6 Latin American Journal of Aquatic Research a b Figure 2. a) Wave height (Hs), b) peak period (Tp) in the mean wave regime for the most likely magnitudes of winds and swell during the wet season. Three groups of mangrove stand related to the environmental variables analysed were identified by the RDA (Fig. 4, Table 2). The first group corresponds to the A. germinans dominated mangrove stands of the eastern zone that had the highest values of pore water pH and the greatest percentages of sand in the soil, but lower wave periods (Tp) and wind speed. This group recorded the highest basal area of A. germinans (10 m2 ha-1) and not only had the greatest density of small trees (2.5 < DBH <10 cm) but also the lowest mean basal area (3.59 m2 ha-1 of R. mangle and 1.31 m2 ha -1 de L. racemosa) R. mangle had the highest seedling abundance. All these parameters were also related to lower percentages of clay and organic matter in the soils when compared to the other groups. The second group includes the mangrove stands located to the north of the western zone and is characterized by the high relative abundance of L. racemosa adult trees, as well as L. racemosa and R. Mangle seedlings. These vegetation features were positively related to sediment deposition and pore water pH, but negatively related to the wave period (Tp). The third group includes the forests located towards the south of the western zone and is characterized by the high dominance of R. mangle in all size categories and the low relative abundance of Pelliciera rhizophorae and non-mangrove species. In this area there were higher percentages of clay and organic matter in the soils and high wind speeds. The third group is clearly related to the maximum values of Hs (0.15 m) and Tp (4.5 s). The strong relationship between Tp and R. mangle seedling density (Fig. 4b, Table 2) might be the result of wider propagule dispersion due to the increase in Tp. In summary, the vegetation structure was highly correlated not only to physical environmental variables such as the percentage of organic matter in the soils and pore water salinity and pH, but also to hydrodynamic variables like the maximum Tp, wind speed and river flow (Fig. 4, Table 2). Temporal vegetation analysis and sediment dynamics According to the remote sensing and the 210Pb analysis, the highest sediment deposition rate was recorded at Table 1. Multiple regression analysis between dependent variables (vegetation variables) and environmental, oceanic, climatic and anthropogenic variables (independent variables). DBH: diameter at breast height (cm), Hs: significant wave height, Tp: peak period of waves, coastal processes, 100: sedimentation, 50: stability, 1: erosion, river flow (m3 s-1), wind speed measured during the wet season, distance Hs: distance to humane settlements (m). Oceanic and climatic drivers of mangrove changes 978 7 sites flooded by rivers, mainly in deltas and on river banks where either the river flow or the wind speed was rather low (Fig. 3). However, both zones showed contrasting sediment dynamics. The sedimentation rates measured along sediment cores showed changes between 1939 and 2009, from 0.41 to 1.37 cm yr-1 (mean= 0.96 cm yr-1) in Candelaria Bay (western zone), 0.34 to 1.50 cm yr-1 in El Uno Bay (eastern zone) (mean= 1.16 cm yr-1). While new accreted zones increased 0.4% in the western zone between 1975 and 2009, in the eastern zone they grow 14.9% between 1980 and 2009. The multi-temporal analysis based on aerial photographs, revealed that 26.6% of the study area was occupied by fringe mangroves. Of these, 83.7% were located along the western zone of the gulf and 16.3% are along the eastern zone. Along the western zone, the expanse of fringe mangroves, dominated by R. mangle, on newly deposited substrates offshore increased by 22% between 1975 and 2009 (Table 3). These new areas were formed by accretion processes along the banks of the Atrato River in wind and surge protected bays. While mangrove areas increased in accreted places previously occupied by water bodies (rivers, lakes or sea), mangroves losses occurred in eroded zones formerly covered by mangroves but appeared occupied by these water bodies at the end of analysed period. The eastern zone had a higher input of sediments and was less affected by strong winds than the western zone. The higher percentages of sand found in the soils (Fig. 3) were associated to littoral drift, higher significant wave height and sedimentation along the river beds. It caused increased of bare area by about 500% between 1980 and 2009. During this time span, 78 ha of fringe mangroves were lost due to coastal erosion and onshore coastline displacement (Fig. 3). In addition, the urbanized area increased by 20% (1.13 ha yr-1) at the expense of basin and fringe mangroves. Fringe mangroves were dominated by R. mangle close to the shoreline, but where daily tidal influence diminished onshore, the dominance of A. germinans and L. racemosa increased. In the western zone, between 1975 and 2009 the mangroves grew on 80.4 ha of newly deposited substrates along the Atrato River banks. Besides these new areas, 62.2 ha were colonized by grasses and salt marshes and the bare areas diminished. The highest rates of erosion and the greatest mangrove losses were recorded (195 ha) at both the north and south extremes of the Atrato River delta. These processes were associated to the highest recorded wave energy, with Hs values of 0.2 m in the wet season and 0.5 m in the dry season, respectively. 979 8 Latin American Journal of Aquatic Research Figure 3. Environmental variables trend analysis. Green lines show the projection of the spatial variability of each variable from west to east (X axis). Blue lines show south-north variability (Y axis). While in the western zone, 14.2 ha of early successional mangrove stands were lost due to coastal erosion, onshore tidal flooding and conversion into grasslands, in the eastern zone, 29.29 ha of these mangrove stands were lost in the studied periods. These mangroves were displaced by tropical rain forests, which grow on recent deposited due to the increase in alluvial sediment input, especially sands, as well as an improvement in drainage conditions and soil stabilization, and a decrease in pore water salinity. This impeded young mangrove tree species from competing with non-mangrove species. The remaining young mangrove stands (13.81 ha) of the eastern zone were lost due to coastal erosion in sites affected by strong winds (1.6 m s-1), and waves (20 cm). DISCUSION Relationship between hydrodynamics and vegetation structure The extended natural regeneration of mangroves in the gulf is related to physical and anthropogenic processes that have occurred in the region during last 30 years. In particular, changes in sedimentation processes have led to high relative abundances of A. germinans and L. racemosa. The influence of waves and littoral drift on the eastern gulf clearly shows that the accumulation of sediments along the river spits gave place to formation of new lands that plays an important role in the colonization of mangroves. The natural regeneration of A. germinans in the gulf is related to the high porewater salinity and the percentage of sand in the soils. The survival of seedlings and saplings of this species is associated not only to higher salinity and sedimentation processes, but also to the increased availability of light caused by anthropogenic disturbance of the forest (Clarke & Allaway, 1993; Mckee, 1995). While the establishment of Rhizophora implies high soil humidity and organic matter accumulation (Lacerda et al., 1995), sites colonized by Avicennia are continuously losing organic matter due to the aforementioned factors (Rajkaran & Adams, 2012). In the western zone, R. mangle-dominated mangroves recorded 19.2 cm and 12.8 m of average tree 9809 Oceanic and climatic drivers of mangrove changes a b Figure 4. Relation among variables from the redundancy analysis. a) Biplot of vegetation plots (circles) and oceanic and climatic variables (arrows), b) biplot of vegetation variables (dotted arrows and solid arrows). AG: Avicennia germinans, RM: Rhizophora mangle, LR: Laguncularia racemosa. 981 10 Latin American Journal of Aquatic Research Table 2. Results of the redundancy analysis, canonical coefficients and intra set correlations of environmental variables for the first two axes of RDA. Redundancy analysis of correlation matrix. Axis Eigenvalues Plot-variable correlations Cumulative percentage variance of plot data of the plot-environment relationship Variable Wave height Peak period Coastal processes River flow Clay Sand Salinity Pore water pH Soil pH Organic matter Wind speed 1 2 3 4 0.28 0.09 0.08 0.03 0.89 0.76 0.64 0.67 28.1 37.4 45.5 48.7 51.1 68.1 82.8 88.8 Coefficients Axis 1 Axis 2 -0.25 0.009 -0.28 -0.78 -0.03 0.15 0.24 0.13 -0.003 1.31 0.39 0.48 -0.23 -0.58 -0.35 -0.25 -0.22 0.51 -0.11 -0.98 -0.12 0.39 Total variance 1 Correlations Axis 1 Axis 2 0.1 -0.11 -0.50 -0.11 0.33 0.19 0.14 0.30 0.29 -0.51 0.33 -0.20 -0.21 -0.62 0.20 0.07 0.59 -0.35 0.14 -0.51 -0.37 0.25 Table 3. Expanses of the types of vegetation cover (m2 ha-1) in the western and eastern zones of the Gulf of Urabá. Losses and gains are indicated by negative and positive sign, respectively. Coverage Fringe mangroves Basin mangroves Early successional mangroves Alluvial forests Grasslands Without coverage Urban zone Western zone 1975 2009 % 1906.6 2325.3 +22 286.8 3291.2 2304.1 223.7 3307.6 2494.8 38 -100 +0.5 +8.3 -83 DBH and height, respectively, and basal areas 17.39 m2 ha-1. These values are higher than those recorded in mangroves of La Guajira at the north-eastern Colombian Caribbean (Molina, 2009), where the R. mangle-dominated mangroves showed values of 8.8 cm and 6.6 m of average tree DBH and height, respectively, and mean basal areas of 12.9 m2 ha-1. And they are also higher than those exhibited by fringe mangroves in the Island of San Andrés (also in the Caribbean) with average values of 6.25 of DBH, 9 m of height, 16 m2 ha-1 of basal area (Urrego et al., 2009). These larger heights and basal areas recorded in mangrove trees in the gulf when compared with other Colombian Caribbean mangroves are a result of high rainfall, freshwater, nutrient and sediment input from rivers. This causes salinity diminutions and an impro- 1980 238.4 137.3 89.2 321.4 411.4 11.6 158.2 Eastern zone 2009 % 451.6 +89.4 97.3 -29.1 -100.0 381.2 +18.6 349.6 -15 71.8 +519 191.1 +20.8 Total 1975-80 2009 2145 2777 137.3 97.3 376 0 3612.5 3688.8 2715.5 2844.4 235.7 109.9 158.2 191.1 % +29.5 -29.1 -100 +2.1 +4.7 -53.4 +20.8 vement in mangrove productivity, as has been widely recorded for other mangroves (Menezes et al., 2003; Krauss et al., 2006a, 2006b; Rajkaran & Adams, 2012). The best mangrove structure (R. mangle), represented by higher basal areas (22 m2 ha-1) and taller (7 m) trees, was recorded far away from urbanized areas like the city of Turbo (in the eastern zone) or the Bocas de Atrato Village (in the western zone). However, mangroves closer to them showed smaller tree diameters (8.3 cm) and basal areas (7.1 m2 ha -1) (Estrada, 2014). This is the reason for the dominance of small sized (<5 cm) R. mangle trees and a lack of trees with a DBH greater than 20 cm in the surroundings of urban areas. The same situation is found in other anthropogenically disturbed mangrove swamps (LópezHoffman et al., 2006). In mangrove swamps in the Gulf Oceanic and climatic drivers of mangrove changes of Urabá, the selective logging of R. mangle of both large diameter mangroves for construction and small diameter mangroves to make fishing poles is quickly reducing their populations. The greatest number of juvenile trees, the smallest basal areas, and most light are commonly found in these anthropogenically disturbed forests (Walters, 2005b). However, the distance to urban populations also explains the high relative abundance of A. germinans, since the increase in open canopies in disturbed areas favors its establishment and growth. In addition, close to towns selective logging removes juvenile and adult R. mangle and L. racemosa trees, allowing A. germinans trees to reach a higher DAP and establish extended stands in heavily managed patches, giving a higher density of trees of this species Human pressure on mangroves can lead to changes in the dynamics of the natural regeneration and structure of mangrove forests (Benfield et al., 2005; Walters, 2005a), depending on the physiology and environmental requirements of each of the species. Multi-temporal analysis of vegetation cover The expansion of fringe mangroves along the Gulf of Urabá is mainly related to the formation of new available lands fed by the increase in fluvial sediment input. Major expansions have taken place in river mouths and deltas where the wave energy is dissipated by river currents and the sedimentation of coarse sediments is more feasible, as has been recorded in other areas of the Colombian Caribbean (Molina, 2009; Urrego et al., 2014) and French Guyana (Proisy et al., 2009). Mangrove expansion is favoured by two forces that counteract each other simultaneously: firstly, the increase in sediment accumulation (40 m yr-1 between 1940 and 1999 in the eastern zone in the mouth of the Turbo River) (Correa & Vernette, 2004) and secondly the sea level rise from 1993 to the present (Average global sea level rise of 3.1 mm yr-1) (IPCC, 2007). An increase in the mangrove extensions was favoured by the sediment input from the Turbo River diversion in the 50´s which caused an increase of 32% (from 305.38 to 403.29 ton yr-1 km-2) in sediment transport along the river bed between 1946 and 2004 (Posada, 2011) that created new deposited substrates to be colonized by vegetation. Both processes have contributed to substrate stabilization and the creation of new sites for mangrove colonization (Parkinson et al., 1994; Gilman et al., 2008). However, mangroves may expand onshore as a response to sea level rise, when an extensive flat coastal plain is available. There, mangroves can establish themselves at the expense of other vegetation types or anthropogenic land uses. Such intertidal land recla- 982 11 mation by mangroves has been also recorded in other Caribbean regions (Benfield et al., 2005) and has caused the replacement of some vegetation types by water bodies. The highest mangrove expansion recorded in the eastern zone is related to the small size of basins on the new lands created by the high sediment loads brought in by rivers (Restrepo & Kjerfve, 2000; Arroyave et al., 2012). High sedimentation rates have been associated with the increase in river bank deforestation during the second half of the XX century which favoured the export of sediments (Arroyave et al., 2012; Blanco-Libreros et al., 2013). In fact, annual deforestation rates around the Turbo River headwaters from 1960-2007 are among the highest in the world (1.36%; Blanco-Libreros et al., 2013). In addition, important vectors of regional development such as agricultural and urbanized lands (Taborda & Blanco, 2012) have expanded during recent decades at the expense of the natural vegetation covers. Increases in mangrove cover along the shorelines of the gulf are related to the increment in sediment input from the Atrato River, especially to the artificial Turbo River bed diversion created in 1954 (Posada, 2011). At these sites, the colonization of vegetation has followed the typical pattern recorded in other places, e.g., the growth of R. mangle on recent river bank deposits and A. germinans on the boundary between the filling area and the dikes (Thom, 1967). In addition, the direction of the littoral drift prevents deltaic sediments of the Atrato River from being distributed along the coasts of the gulf. Therefore, sand spits are also fed by biogenic contributions from cliffs in the western zone and small rivers in the eastern zone (Francois et al., 2007). With regards to wave direction and geomorphological features, the prevailing drift has a southerly direction on both coasts, although seasonal variations occur (Molina et al., 1992; Chevillot et al., 1993; Bernal et al., 2005a; Montoya & Toro, 2006). Despite the predominance of the high flow of the Atrato River in the western zone of the gulf, sedimentation and mangrove colonization rates are higher in the eastern zone. This is not only due to littoral drift and high river sediment loads, but more importantly due to low wave energy. According to Molina et al. (2014) the patterns of littoral drift along the Eastern Gulf are clearly dominated by the oblique incidence of the NW and NNW wave direction. This is the main mechanism of longshore currents along the eastern coast and therefore the main driver of littoral drift. For example, the magnitude of potential sediment transport (based on the influence of wave direction) in Punta Yarumal (the mouth of the Turbo River) is about 23,523 m3 yr-1 during the dry season, when the littoral drift increases, and around 6,326 m3 yr -1 during the wet season 983 12 Latin American Journal of Aquatic Research (Posada, 2011). This pattern may explain the sedimentation of the spits and the mangrove colonization rates in the eastern gulf. CONCLUSIONS According to our results, the distribution, structure and composition of mangroves in the Gulf of Urabá are closely influenced by oceanic, climatic and anthropogenic drivers. There is a strong relationship between sediment acumulation and the increse in mangrove expanses in the gulf in sites sheltered from waves, winds and littoral drift where there is also a high fluvial sediment input. In contrast, the highest mangrove loss was recorded in sites highly impacted by waves (high values of Hs and Tp) and coastal erosion processes. Although it is clear that the establishment and distribution of mangrove stands are strongly related to the influence of Tp and Hs, our results cannot be generalized since it is necessary to gather more field data about the relationship between wave speed (related to Tp) and the colonization process, as well as the drag force and mangrove hydraulic properties during extreme events. Despite the relationship between mangrove distribution and physical factors, there is a clear anthropogenic impact on mangrove structure and composition. While the density of A. germinans increases with distance to human settlements, the relative abundance of R. mangle and L. racemosa decreases. 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Felipe Becerril-Morales1 & Juan Pablo Alcántar-Vázquez1 Laboratorio de Acuicultura, Dependencia de Educación Superior, Ciencias Agropecuarias Universidad del Papaloapan (UNPA), Av. Ferrocarril s/n, Col. Ciudad Universitaria Loma Bonita, Oaxaca, C.P. 68400, México 1 Corresponding author: Juan Pablo Alcántar-Vázquez ([email protected]) ABSTRACT. Early maturity during tilapia culture is a recurring problem. To avoid this, a series of techniques have been developed, including the production of YY-males. This technique involves the use of hormones to produce phenotypic females (XY genotype). However, incomplete transformations are frequently observed and the produced atypical feminized males (AFM) could display an ambiguity in the phenotypic expression of behavioral patterns. The aim of this study was to measure the frequency and intensity of aggressive behavior as well as the role that initial residence plays when involving three phenotypes (males, females and AFM). The experiment consisted of three stages. Resident fish were AFM in the first stage, males in the second and females in the third. In each stage the resident fish confronted males, females and AFM acting as intruders. Aggressive behavior was exercised more frequently by resident fish. Intersexual confrontations showed higher levels of aggression compared to intrasexual confrontations. The frequency of confrontations was not significantly different in confrontations involving AFM, however, differences were observed in intensity of aggression. It is possible that an incomplete transformation at physiological level could be responsible for an inaccurate decoding of signal during confrontations. Keywords: Oreochromis niloticus, agonistic behavior, atypical feminized males, aquaculture. Comportamiento agonístico de machos feminizados atípicos en relación a machos y hembras de tilapia del Nilo (Oreochromis niloticus L.) RESUMEN. La madurez temprana durante el cultivo de tilapia es un problema recurrente. Para evitarlo, existe una serie de técnicas, incluyendo la producción de machos-YY. Esta técnica implica el uso de hormonas para producir hembras fenotípicas (genotipo XY). Sin embargo, son frecuentes transformaciones incompletas y los machos feminizados atípicos (MFA) producidos podrían mostrar ambigüedad en la expresión fenotípica de los patrones de comportamiento. El objetivo del presente trabajo fue determinar la frecuencia e intensidad del comportamiento agresivo, así como el papel que juega la residencia inicial al involucrar tres fenotipos (machos, hembras y MFA). El experimento abarcó tres etapas. En la primera etapa, MFA actuaron como residentes, en la segunda machos, y en la tercera, hembras. En cada etapa el residente enfrentó a machos, hembras y MFA que actuaron como intrusos. El comportamiento agresivo lo ejercieron con mayor frecuencia los peces residentes. Las confrontaciones intersexuales mostraron mayores niveles de agresión en comparación con las intrasexuales. La frecuencia de confrontaciones no fue significativamente diferente en confrontaciones que incluyeron MFA, sin embargo, se observaron diferencias en la intensidad de la agresión. Es posible que una transformación incompleta a nivel fisiológico pueda ser responsable de una decodificación incorrecta de señales durante las confrontaciones. Palabras clave: Oreochromis niloticus, comportamiento agonístico, machos feminizados atípicos, acuicultura. In Mexico, tilapia represents 60% of the production of farmed fish and is estimated to reach an annual production of 200,000 ton by the year 2020 (Norzagaray et al., 2013). Tilapia culture, specially the __________________ Corresponding editor: Sergio Palma one of Nile tilapia (O. niloticus), offers many advantages over other fish species. However, and despite its relatively low fecundity (Phelps & Popma, 2000), the control of its early maturity is a recurring problem. In mixed-sex cultures, Nile tilapia fish reach 2987 Latin American Journal of Aquatic Research sexual maturity (30-50 g) long before commercial size (350-400 g) (Jiménez & Arredondo, 2000; ArboledaObregón, 2005). To avoid this, a series of techniques have been developed in recent years. One of the more promising techniques involves the production of YYmales, which, when combined with normal females (XX) produce progenies composed of 100% genetic males. While the ultimate goal of YY-technology is to reduce the use of hormones, the first step of this technology still involves using hormones to feminize normal male fry (XY). This produces a phenotypic transformation, i.e. the morphology and function of adult females from male fingerlings (Vera & Mair, 2000; Ovidio et al., 2002; Desprez et al., 2003). During this process, it is common to observe the presence of atypical fish, in this case atypical feminized males (AFM), which are normally characterized by having either abnormal genital papilla or male papilla and with ovaries. AFM are usually discarded due to the suspicion of not having a functional oviduct resulting from a morphologically incomplete transformation. Previous experiments performed in our laboratory have shown that AFM selected were not only able to generate a number of viable fry, but also a sex ratio that confirms the presence of an XY genotype (Alcántar-Vázquez et al., 2014). However, the number of spawns obtained from crosses between AFM and normal males was lower compared to those where normal females are used and in some cases it was possible to observe severely beaten AFM when they were placed in a reproduction tank with one male of similar size, suggesting some physiological disorder. It is possible that in the AFM, an ambiguity in the phenotypic expression provoked by the differences between morphology and functionality of sexual structures could have a profound behavioral effect, for example in the aggression behavior, which is relevant to fish populations in terms of social structure, levels of stress and, consequently, in the overall performance of fish farming (Øverli et al., 2002; Huntingford et al., 2006; Boscolo et al., 2011). In the context of animal behavior and particularly in what is known as fight theory (Maynard-Smith, 1982; Riechert, 1998; Arnott & Elwood, 2009; Mowles & Ord, 2012), the AFM represents an interesting opportunity to observe how to resolve conflicts against opponents with similar fight capabilities (RHP) based in their phenotype (females) but with probable differences arising from its genotype (males). During a conflict between fish of either the same sex (intrasexual) or the opposite sex (intersexual), aggression can be defined as a behavior directed to harm or intimidate another individual. It is known that in vertebrates the mechanism of hormonal regulation acts on the central nervous system, closely interacting with sex determination at the embryonic level (SalameMéndez, 1998) and with how aggression is expressed between fish (Rosvall et al., 2012). The objective of this work is to measure both the frequency of certain behavioral components used as indicators of confrontation intensity as well as the role that initial residence (dominance of a site) plays when involving the three phenotypes usually present in a population of Nile tilapia subjected to the sex reversal process. Considering that the feminization process involves morphological and functional (physiological) transformation from male to female, it is assumed that the change extends to the behavioral level. Typically, females are less aggressive than males, which are more commonly involved in confrontational behavior related to the dominance of a given site (Bradbury & Vehrencamp, 1998). Considering a likely modified physiological profile in sex-reversed fish in a context of confrontation dyads, in this work we predict that AFM will display behavior different from normal females in both frequency and intensity of aggressive behavior against normal male and female fish. The experimental Nile tilapia fish (O. niloticus) fish used in this study was males, females and atypical feminized males (AFM) from the same batch. All were produced using locally available strains (Centro Acuícola de Temascal, Oaxaca and Sistema Cooperativo Integral, Veracruz) in the experimental aquaculture station from the Universidad del Papaloapan (18°06′N, 95°53′W; at a height of 30 m above sea level) and maintained in 3 m diameter concrete tanks with recirculating fertilized water. AFM were produced by feeding fry at swim-up stage with 120 mg of E2 kg-1 of powdered tilapia pellets for 30 days. Before starting the experiment, fish were reared up to sexual maturity (six months of age) and fed with a commercial diet according to their stage of development. In total, 72 fish were used for this experiment on confrontations. The study was conducted in a recirculating water system composed of 12-85 L acrylic aquaria. Water in the recirculating system was filtered with a mechanical filter (Hayward, Model S310T2, Hayward Pool Products Inc., Elizabeth, NJ, USA) and a biofilter containing only plastic Bio-Balls (Aquatic Eco-System, Model CBB1, Pentair Ltd., Apopka, FL, USA) and then passed through a UV lamp (Lumiaction, Model BE1X20, Lumiaction Co. Ltd., Taipei, Taiwan). During the period of treatment, a photoperiod of 12L:12D was used and water temperatures were thermostatically controlled and maintained at 28 ± 1ºC. All aquaria were covered with non-reflective paper on three sides and Agonistic behavior of atypical feminized males separated 2 cm from each other to prevent the fish could see or interact with the fish from other aquaria. The experiment consisted of three stages. Resident fish were AFM in the first stage (designated AR), males in the second (designated MR) and females in the third (designated FR). In each stage the resident fish confronted males, females and AFM all acting as intruders. Each combination was carried out in quadruplicate form and randomly assigned. A resident was defined as the fish that occupied each aquarium in the first instance. Before each stage, residents remained in the aquaria for a period of seven to ten days for acclimatization. During this period, fish were fed with commercial diet at 25% protein two times a day. Each intruder was previously weighed using a digital scale (± 0.01) (Scout Pro, Ohaus) to ensure that its size were as similar as possible (± 20 g) to the size of the resident. Additionally, considering that the ability to fight may involve the length or weight of the contender, we decided to use an index that considers both simultaneously, so standard and total length were obtained using an ictiometer, in order to calculate the fish condition factor (Froese, 2006). Confrontations were recorded at different times of day (except at night) for a full minute using a digital camera (Sony Handycam DCR-DVD 610). Each recording session consisted of the recording made at a specific time of all combinations presented in the aquaria. Each stage lasted for a period of 24-h, consisting of a variable number of sessions (5 in AR, 6 on MR and 7 in FR). The first session of recording in each stage lasted for 2 min with the objective to measure the latency, that is, the elapsed time (in seconds) from the moment the intruder was placed into the aquaria until the first observed interaction between resident and intruder. After completing each stage, the fish were returned to 3 m diameter quarantine tanks for recovery before being transferred along with the rest of the population. Recordings were cataloged and sorted to obtain the following behavioral patterns: number of interactions in a minute of observation (in the first session, data were taken during the second minute), number of interactions for each fish (resident/intruder), and intensity level of aggression (I to V scale, based to the operational definitions of Evans et al. (2008), level I: body facing the opponent and erect dorsal fin; level II: fast and directed movement towards the opponent without physical contact; level III: short and lateral movements making contact with the mouth on the side of the opponent; level IV: chasing the opponent; level V: contact with both fish mouths, pushing the opponent). Finally, the number of times that an individual recoiled after the attack (called submission) was included. These observations were performed for each opponent (focal observations). 9883 Aggressive behavior was calculated by subtracting the number of submissions from the number of aggressions recorded for each fish. This value can be positive (high aggressiveness), negative (high submission) or zero (aggressiveness-submission in equal terms). Median, quartiles and extreme values were calculated. Since in most fights, the majority of confrontations occurred in the first observation session (in the rest, the number of confrontations represent only 13%), data were pooled for each category of contenders and compared as independent groups (different aquaria) using a Wilcoxon or Kruskal Walllis test. We calculated the proportion of each intensity level of aggression with respect to the total number of confrontations and then compared in terms of the residence roles and sex categories. A chi-square test of independence was applied in a contingency table to measure the relative frequencies between level of aggression and type of confrontation. The proportion values obtained were arcsine transformed and then analyzed using an ANOVA test for each type of confrontation, using as classification variable the levels of intensity of aggression (Zar, 1984). Condition factor was calculated using basic Fulton’s equation (K = 100x W/L3; see Froese, 2006), and length (L) and weight (W) data. Comparisons between contenders were applied using t Welch test. All tests were performed at 0.05 significant level. All of our comparisons showed no significant differences in terms of condition factor (t-Student statistic, all P > 0.05) and time of latency between categories of contenders (H = 7.19; DF = 8; P = 0.517). However, time of latency showed a tendency to be longer and more variable when resident females were faced with female intruders. Each resident fish showed an increase in aggressive activity once a second fish, an intruder, was placed into the aquarium. Aggressive behavior (in relation to submissive behavior) was exercised more frequently by resident fish (Fig. 1). Intrasexual confrontations (malemale and female-female) showed a lower median number of attacks when compared to intersex confrontations (male-female), however, no significant differences were detected (H = 2.81; df = 3; P = 0.422). In confrontations where AFM were involved either as residents or as intruders, the median number of attacks was not significantly different (H = 4.05; df = 4; P = 0.399) to that observed in confrontations between normal males and females. As with the number of attacks, no significant differences (W = 11,153.5; P = 0.78) were observed in the frequency of attacks between confrontations with or without AFM. However, confrontations involving AFM displayed a tendency toward a higher frequency of attacks. In general, when comparing the role of residentintruder against the intensity of aggression in all com- 4989 Latin American Journal of Aquatic Research Figure 1. Relative differences between aggression and retreats (submission), according the role of resident or intruder of each contestant (mean: black box, median: horizontal line; quartiles: box, extreme values: asterisks) (P > 0.05). The top panel refers to interactions with atypical feminized males (AFM). The bottom panel refers to inter and intrasexual confrontations between normal males and females. binations recorded, significant differences (chi-square = 178.03; df = 24; P < 0.001) were observed in the relative frequency of each intensity level of aggression and the mean proportion of different aggression levels (F values are showed in Fig. 2). Two levels of intensity were in proportion more frequent: the less intense aggression (level I) and one in which there was physical contact with the mouth on the side of the opponent (level III). Intrasexual confrontations showed almost no increase in intensity of aggression, while intersexual confrontation showed in each confrontation an increase in intensity (level III). Meanwhile, in confrontations that included AFM, it was observed that, as residents, they showed a higher level of aggression (level III) only toward other AFM. As intruders, AFM were attacked with more intensity (level III) in almost all cases by both males and females. In some confrontations, male aggression toward AFM reached a level IV (Fig. 2). There are few references to aggressive behavior of sex-reversed fish, particularly males transformed into females. According to our results, AFM behave like normal females but with differences at inner aggressive behavior, something knows as behavioral pattern (Lehner, 1996). This is supported by the fact that AFM were not shown to be more aggressive than normal females or males with respect to frequency of aggressive behavior but did prove to be so in terms of intensity level. This result contrasts with that observed by Ovidio et al. (2002), who reported that aggressive behavior in feminized males was higher when compared to that observed in normal females, a result based only on the frequency of confrontations and not, as was observed in our study, on the differential occurrence of certain behavioral acts. In our work, AFM had genital papilla which retained mainly the male form with no obvious oviduct but that could expel viable eggs after abdominal massage. It is possible that this incomplete transformation at morphological level could be associated with an incomplete transformation at the physiological level, which in turn could be responsible for the altered agonistic behavior observed in AFM (AlcántarVázquez et al., 2014). According to Varadaraj (1989), partial transformations can occur, apparently caused by variations in dose, and to a lesser degree, by duration of exposure to the hormone. Therefore, partial transformation could produce not only an incomplete sex-reversal from male to female at physiological level but also an incomplete transformation at tissue level, more specifically at gonadal tissue, generating intersex individuals (with both types of gonadal tissues at the same time). Chemical signals translated to behaviors coming from this intersex gonad could be mixed and ambiguous in AFM. There is evidence that aggressive behavior in mice is the result of hormonal action rather than chromosomal differences between sexes (Canastar et al., 2008). Agonistic behavior of atypical feminized males 9905 Figure 2. Proportion of behavioral components (levels of aggression) for different contender’s combinations (role of resident-intruder and sex categories). Mean median, quartiles, and extreme values are presented. Statistic values for ANOVA tests among levels of aggression are presented for each type of confrontation. ♂ = male, ♀ = female, A = atypical feminized males (AFM). It is possible then to consider that in other vertebrate groups such as fish something similar would occur and the underlying differences between the experimental groups analyzed would be related only to the effect of the levels of sexual hormones. Therefore, it is possible that the incomplete feminization reached at the physiological level could be responsible for increasing intensity of the aggressive behavior displayed by and toward the AFM. This could provoke, as our data suggests, that AFM behave similarly to females or males depending on the sex of the resident with whom they share the aquarium. Although an incomplete feminization could be responsible for the agonistic behavior observed in the AFM, we cannot rule out the effect on hormonal patterns and therefore on behavior of the interaction of the three components that govern sex in the Nile tilapia: a complex genetic sex determination system with a major determinant locus, some minor genetic factors, as well as the influence of temperature (Baroiller et al., 2009). Baroiller & D´Cotta (2001) mention that fish have certain plasticity during sex differentiation since several functional sex phenotypes can be generated by diverse mechanisms, including sex-reversal. Therefore, a sex-reversed fish, especially an atypical one, would show altered hormonal patterns caused by the combination of gene expression of sex genes of both sexes, in this case, probably male sexual genes that were not completely inactivated due to an incomplete feminization at genetic level. These altered hormonal patterns will finally be reflected in an altered behavior of AFM (more aggressive in intensity) or in the sending of mixed signals (combination of the expression of genes of both sexes) that would cause further aggression against them. Aggressive behavior was issued by the resident toward the intruding fish. In most cases the lower level of aggression was the most frequent (dorsal erection). Based in our results on time of latency, residents probably did not make distinctions when evaluating (to confront) different types of intruders. Therefore the conflict, by the dominance, usually was resolved quickly and with little effort made by the resident. In our work, it was possible to observe that male and female residents increased the intensity of confrontation only toward intruders of the opposite sex while AFM acted similarly only against other AFM. In the first case, it is probable that confrontations emerged between sexes had an origin based on a conflict associated with the reproductive process (Shuster & Wade, 2003). In the second case, it is possible that the aggression intensity rose due to the fact that they faced fish whose responses to agonistic signals were ambiguous. In consequence, fish that escalated con- 6991 Latin American Journal of Aquatic Research frontation by showing more aggression, reiterated and even magnified signals originally issued in low aggression levels (Payne & Pagel, 1997). This emphasizes why behavioral acts such as "persecution" (level IV of aggression) have predominantly occurred in cases of confrontation with AFM. In this experiment, it was not the confrontation frequency but rather the way each aggressive confrontation was displayed (different proportion of behavioral components) that determined the patterns of aggressive behavior observed in males, females and AFM. Our experiment suggests one of two possible scenarios for the confrontation dynamics observed: in the first scenario, the resident fish was required to escalate to a higher level of aggression even if the intruder decided not to repel the attack, probably because the intruder showed signs (perhaps chemical) received by the resident fish as a challenge to dominance of the territory (aquarium). In the other scenario, it is probable that resident fish fell into a mechanized behavior (stereotypy) and exerted unnecessary and unavoidable higher levels of aggression. It is not clear why, in the case of O. niloticus, a dominant fish can apply a level of aggression that results in death of a subordinate fish. Although some studies have insisted on the artificiality that surrounds this kind of experimental observations made in conditions of captivity, particularly in the case of aggressive behavior as a response variable (Sloman & Armstrong, 2002), our experiment showed the relevance of the resident status or intruder on the outcome of fights and that the AFM analyzed possess a behavioral ambiguity, suggesting that these fish probably display altered communication codes that could exert some unbalanced influence in the natural or artificial social environment of fishes. Further investigation would be required to clarify and explain this scenario. ACKNOWLEDGEMENTS The authors thank Nayeli Aguilar for video data register and the Laboratorio de Acuicultura of the Universidad del Papaloapan work group for their technical and logistic support. This project has been supported by PROMEP (Programa para el Mejoramiento del Profesorado) de Mexico (Project; PROMEP/103.5/ 11/6720). Special thanks to James Patrick Killough for editorial improvements. REFERENCES Alcántar-Vázquez, J.P., R. Moreno-de la Torre, D. Calzada-Ruíz & C. Antonio-Estrada. 2014. Production of YY-male of Nile tilapia Oreochromis niloticus L. from atypical fish. Lat. Am. J. Aquat. Res., 42(3): 644648. Arboleda-Obregón, D.A. 2005. Reversión sexual de las tilapias rojas (Oreochromis sp.), una guía básica para el acuicultor. Rev. Electr. Vet., 6: 1-5. Arnott, G. & R.W. Elwood. 2009. Assessment of fighting ability in animal contests. Anim. Behav., 77: 9911004. Baroiller, J.F. & H. D'Cotta. 2001. Environment and sex determination in farmed fish. Comp. Biochem. Physiol. C, 130: 399-409. Baroiller, J.F., H. D ́Cotta, E. Bezault, S. Wessels & G. Hoerstgen-Schwark. 2009. Tilapia sex determination: where temperature and genetics meet. Comp. Biochem. Physiol. A, 153: 30-38. Boscolo, C.N.P., R.N. Norais & E. Gonçalves de Freitas. 2011. Same sized increase aggressive interaction of sex reversed males Nile tilapia GIF strain. Appl. Anim. Behav. Sci., 135: 154-159. Bradbury, J.W. & S.L. Vehrencamp. 1998. Principles of animal communication. Sinauer Associates, Sunderland, 882 pp. Canastar, A., S.C. Maxson & C.E. Bishop. 2008. Aggressive and mating behaviors in two types of sex reversed mice: XY females and XX males. Arch. Sex Behav., 37: 2-8. Desprez, D., C. Melard, M.C. Hoareau, Y. Bellemene, P. Bosc & J.F. Baroiller. 2003. Inheritance of sex in two ZZ pseudofemale lines of tilapia Oreochromis aureus. Aquaculture, 218: 131-140. Evans, J.J., D.J. Pasnik, P. Horley, K. Kraeer & P.H. Klesius. 2008. Aggression and mortality among Nile tilapia (Oreochromis niloticus) maintained in the laboratory at different densities. Res. J. Anim. Sci., 2(2): 57-64. Froese, R. 2006. Cube law, condition factor and weightlength relationships: history, meta, analysis and recommendations. J. Appl. Ichthyol., 22: 241-253. Huntingford, F.A., C. Adams, V.A. Braitewaite, S. Kadri, P.T. Pottinger, P. Sandøe & J.F. Tournbull. 2006. Current issues in fish welfare. J. Fish Biol., 68: 332372. Jiménez, B.M.L. & F. Arredondo. 2000. Manual técnico para la reversión sexual de la tilapia. Serie Desarrollos Tecnológicos en Acuicultura, Universidad Autónoma Metropolitana, Unidad Iztapalapa, 36 pp. Lehner, N.P. 1996. Handbook of ethological methods. Cambridge University Press, Cambridge, 672 pp. Maynard-Smith, J. 1982. Evolution and the theory of games. Cambridge University Press, New York, 234 pp. Agonistic behavior of atypical feminized males Mowles, S.L. & T.J. Ord. 2012. Repetitive signals and mate choice: insights from contest theory. Anim. Behav., 84: 295-304. Norzagaray, C.M., S.P. Muñoz, V.L. Sánchez, F.L. Capurro & C.O. Llánes. 2013. Acuacultura: estado actual y retos de la investigación en México. Rev. Aquat., 38: 20-25. Øverli, Ø., S. Kotzian & S. Winberg. 2002. 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Prentice Hall, New Jersey, 718 pp. Lat. Am. J. Aquat. Res., 43(5): 993-997, 2015 DOI: 10.3856/vol43-issue5-fulltext-19 Chilean coastal underwater soundscape 993 Short Communication Soundscape of a management and exploitation area of benthic resources in central Chile Alfredo Borie1, Natalia P.A. Bezerra2, Sebastian A.L. Klarian3 & Paulo Travassos1 1 Departamento de Pesca e Aquicultura, Universidade Federal Rural de Pernambuco CEP 52.171-900, Recife, Brasil 2 Departamento de Oceanografia, Universidade Federal de Pernambuco CEP 50670-901, Recife, Brasil 3 Centro de Investigaciones Marinas Quintay, Facultad de Ecología y Recursos Naturales Universidad Andres Bello, Valparaíso, Chile Corresponding author: Alfredo Borie-Mojica ([email protected]) ABSTRACT. Acoustic ecology is an emerging and poorly known field of research. Soundscape has been used to infer the behavior of several species in different environments and can serve as a reliable indicator of the habitat type and quality; also, it is believed that it is an important factor for larvae orientation in settlement areas. We used the passive acoustic method to evaluate the soundscape of a management and exploitation area of benthic resources, a rocky reef area in central Chile. It was possible to hear a continuous cracking sound during recording and underwater observations. We detected two distinct frequency bands with similar parameters during the night and day, a band between 90 and 300 Hz, which corresponded to the effects of sea waves (geophony), and a frequency band with a range of 1,500 to 2,700 Hz (biophony), with a fundamental frequency of 2,070 Hz. Both bands had similar energy (~88.0 dB re: 1V/µPa). These results show the relevant acoustic activity in the area, which may have important ecological implications for the recruitment of commercially important benthic resources. Keywords: bioacoustics, acoustic ecology, coastal zone, biophony, geophony, central Chile. Paisaje acústico de un área de manejo y explotación de recursos bentónicos en Chile Central RESUMEN. La ecología acústica es un campo de investigación emergente y poco conocido. El paisaje acústico se ha utilizado para inferir el comportamiento de varias especies en diferentes ambientes y puede servir como un indicador confiable del tipo y calidad de hábitat, además se considera un factor importante para la orientación de larvas en zonas de asentamiento. Se utilizó el método acústico pasivo para evaluar el paisaje acústico de un área de manejo y explotación de recursos bentónicos, en una zona de arrecife rocoso en el centro de Chile. Se escuchó continuamente un crujido durante la grabación y se efectuaron observaciones submarinas. Se detectaron dos bandas de frecuencia con parámetros similares durante día y noche, una banda entre 90 y 300 Hz, que correspondía a los efectos de las olas del mar (geofónico), y una banda de frecuencia con rango de 1.500 a 2.700 Hz (biofónicos), con la frecuencia fundamental de 2.070 Hz. Ambas bandas tenían energía similar (~88,0 dB re: 1V/µPa). Estos resultados muestran la relevante actividad acústica de la zona, que puede tener importantes implicancias ecológicas para el reclutamiento de recursos bentónicos de importancia comercial. Palabras clave: bioacústica, ecología acústica, zona costera, biofonía, geofonía, Chile central. The set of sounds for a given environment can be considered as a soundscape and the use of such sounds for ecological studies can be termed acoustic ecology, an emerging field of ecological research (Pijanowski et al., 2011a). Among the different perspectives with which __________________ Corresponding editor: Diego Giberto it is possible to explore, describe and manage the ecological complexity of such environments, the soundscape may be an excellent proxy for both shortand long-term scientific investigations (Farina & Pieretti, 2012). 994 Latin American Journal of Aquatic Research The subaquatic soundscape could be a composition of several types of sound sources, including biophonics, produced by aquatic mammals, fish and invertebrates in a given environment, but also both anthrophonics (i.e., vessels) and geophonics (i.e., sea waves) (Pijanowski et al., 2011b). Biological sounds have been used to infer the behavior of several terrestrial and recently aquatic species. This production of sounds has been demonstrated in different aquatic environments, such as, the deep ocean (Wall et al., 2014), estuaries (Lillis et al., 2014), coral reefs (Staaterman et al., 2013, 2014). In addition, there are significant differences in the spectral and temporal composition of ambient sound associated with different coastal habitat types (Radford et al., 2010). The characterization of the soundscape could serve as a reliable indicator of habitat type and potentially transmit habitat quality information to disperse organisms (Lillis et al., 2014). The soundscape can be used by larvae of marine organisms to return to settlement areas, in those species where settlement occurs. Research has indicated that juvenile fish (Leis & Lockett, 2005; Radford et al., 2011) and invertebrate larvae (Vermeij et al., 2010; Stanley et al., 2012; Eggleston et al., 2013; Lillis et al., 2013) use sound to locate habitats. The monitoring of changes in the environment and its inhabitants is critical for management and a considerable technological challenge in many marine habitats. Monitoring tools, like passive acoustics, can be an effective way to assess the biological activity in places where continuous monitoring by traditional research methods is not easy or possible. We used passive acoustics to evaluate biophonic and geophonic (sea wave effect) components of soundscape in Quintay (33º11’31”S, 71º42’05”W), one of the Management and Exploitation Areas of Benthic Resources (MEABRs) existing in Chile. Quintay MEABR is a typical rocky coastline of temperate marine environment. The most economically important benthic artisanal resources in this area are the muricid snail (Concholepas concholepas), the red sea urchin (Loxechinus albus) and keyhole limpets (Fissurella sp.) (Fernandez et al., 2000). For an initial approach of Quintay soundscape, we first carried out free-diving observations for 1 h 20 min (starting at 05:00 pm), that helped us to identify representative fauna and potential sound sources in February (summer). In addition, we recorded sounds in natural and captive environments using a hydrophone (H2a Aquarian, sensibility of 180 dB re: 1V/µPa and range of 10 Hz a 100 KHz) connected to a digital recorder (Olympus Digital Voice Recorder VN-701PC). In natural habitat, recordings were made during the night (12:15 am) and day (01:15 pm) at low tide and waning crescent moon, for 8 min and 44 sec each time, in Quintay Bay. Captive species of representative local benthic fauna were recorded in different types of captive systems (ponds, tank and aquaria) at night and day for 10 min in each system in the Quintay Center of Marine Research (CIMARQ) installations. The captive species included L. albus, Tegula atra, Fissurella sp. C. concholepas, and also L. albus seeds with macroalgae, the Chilean blue crab Homalaspis plana, and fishes such as red cusk-eel (Genypterus chilensis), Chilean Figure 1. Spectrogram of soundscape of a management and exploitation area of benthic resources in central Chile. a) 12:15 am, and b) 01:15 pm. Hanning 256 points with 50% overlap, 70% brightness and 90% contrast. Chilean coastal underwater soundscape Figure 2. Soundscape power spectrum of a benthic resource management and exploitation area in central Chile. Red line: 12:15 am, and black line: 01:15 pm. Hanning 256 points with 50% overlap, brightness 70% and contrast 90%. flounder (Paralichthys adspersus) and Paralabrax humeralis. Sounds were analyzed in the software Raven pro v1.4, using acoustic parameters like energy (dB), fundamental, minimum and maximum frequencies (Hz), the analysis of the frequency bins of the acoustic spectrogram can provide proxies for understanding and interpreting acoustic patterns and processes in action across a landscape (Farina & Pieretti, 2012). Continuously audible biological cracking sounds were heard during subaquatic observations. We observed a characteristic benthic diversity in the zone, including patches of macroalgae (Lessonia sp.), echinoderms (L. albus, Tetrapygus niger, Meyenaster 995 gelatinosus, Heliaster helianthus), gastropods (Tegula atra, Fissurella sp., C. concholepas), and crustaceans (Rhynchocinetes typus, Taliepus dentatus) as expected and observed by Fernandez et al. (2000). The spectrogram and power spectrum analyses of natural environment sounds showed two easily distinct bands and peaks respectively, at low tide and waning crescent moon during summer. A continuous band of biophony of cracking sounds and periodic geophony of waves (Fig. 1) were detected during recordings. The cracking bands had similar acoustic parameters to the natural environment during recordings at night (12:15 am) and day (01:15 pm), low and high frequency band between 1,500 and 2,700 Hz respectively, with a fundamental frequency of 2,070 Hz and an energy around 88.0 dB re: 1V/µPa (Figs. 1-2). Radford et al. (2010) found two bands dominated by sea urchins with a peak around 1,000 to 1,200 Hz, and snapping shrimp with a broad peak at 5,000 Hz in New Zealand. A distinct peak (2-4 kHz) was observed in habitat patches, attributable to a snapping shrimp focused in these frequency bands of inshore marine soundscapes (McWilliam & Hawkins, 2013). We found an absence of audible sound in all captive species. This was unexpected; the acoustic signals may be a significant component in the social behavior in crustaceans (Boon et al., 2009; Buscaino et al., 2011). The sea urchin Evechinus chloroticus in captivity can produce sound with frequencies in the range of 800 to 2,800 Hz during feeding, and it was consistent with the dominant component of the ambient chorus recorded near a reef (in the range of 700 to 2,000 Hz) (Radford Figure 3. a) Ocillogram and b) spectrogram of cracking train of a filtered section (1.0 and 5.5 kHz) recorded during the day (01:15 pm). Hanning 256 points with 50% overlap, 70% brightness and 90% contrast. 996 Latin American Journal of Aquatic Research et al., 2008). We found similar fundamental frequency in an isolated cracking composed of a train of pulses, with duration around 10 milliseconds and a variable interval (Fig. 3). For this reason, we believe that biological sounds in our study area were probably produced by the rocky shrimp Rhynchocinetes typus and sea urchin L. albus, even when we did not hear them in captivity. The sea wave effect did not have an influence due to the very low frequency, in our case with a range between 90 and 300 Hz (note the continuously wave sound during the day, Fig. 1b) and the energy (dB) similar to the cracking sounds (Fig. 2). Ambient levels in frequencies affected by surf-generated noise (f <100 Hz) characterize the site as a high-energy end member within the spectrum of shallow water coastal areas influenced by breaking waves (Haxel et al., 2013). In general, the rocky reef soundscape includes bands of small waves, some fish and low frequency noise from distant shipping and offshore storms in a 100 to 800 Hz range (Radford et al., 2010). Quintay soundscape could indicate that sounds can be used for larval orientation of important economic benthonic resources like C. concholepas and L. albus. However, we still need to evaluate the possibility of soundscape seasonality (including biophonic and anthrophonic sounds) during future long-term monitoring and find out the potential biological sound sources and larval orientation by sound in protected and exploited marine areas. REFERENCES Boon, P.Y., D.C.J. Yeo & P.A. Todd. 2009. Sound production and reception in mangrove crabs Perisesarma spp. (Brachyura: Sesarmidae). Aquat. Biol., 5: 107116. Buscaino, G., F. Filiciotto, M. Gristina, A. Bellante, G. Buffa, V. Di Stefano, V. Maccarrone, G. Tranchida, C. Buscaino & S. Mazzola. 2011. Acoustic behaviour of the European spiny lobster Palinurus elephas. Mar. Ecol. Prog. Ser., 441: 177-184. Eggleston, D., A. Lillis & D.R. Bohnenstiehl. 2013. Larval settlement in response to estuarine soundscapes. J. Acoust. Soc. Am., 134(5): 4148-4148. Farina, A. & N. Pieretti. 2012. The soundscape ecology: a new frontier of landscape research and its application to islands and coastal systems. J. Mar. Isl. Cult., 1: 2126. Fernandez, M., E. Jaramillo, P. Marquet, C. Moreno, S. Navarrete, P. Ojeda, C. Valdvinos & J. Vasquez. 2000. Diversity, dynamics and biogeography of Chilean benthinc nearshore ecosytems: an overview and gidelines for conservation. Rev. Chil. Hist. Nat., 73: 797-830. Haxel, J.H., R.P. Dziak & H. Matsumoto. 2013. Observations of shallow water marine ambient sound: the low frequency underwater soundscape of the central Oregon coast. J. Acoust. Soc. Am., 133(5): 2586-2596. Leis, J.M. & M.M. Lockett. 2005. Localization of reef sounds by settlement-stage larvae of coral-reef fishes (Pomacentridae). Bull. Mar. Sci., 76: 715-724. Lillis, A., D. Eggleston & D.R. Bohnenstiehl. 2013. Oyster larvae settle in response to habitat-Associated Underwater Sounds. PloS ONE, 8: e79337. Lillis, A., D. Eggleston & D.R. Bohnenstiehl. 2014. Estuarine soundscapes: distinct acoustic characteristics of oyster reefs compared to soft-bottom habitats. Mar. Ecol. Prog. Ser., 505: 1-17. McWilliam, J.N. & A.D. Hawkins. 2013. A comparison of inshore marine soundscapes. J. Exp. Mar. Biol. Ecol., 446: 166-176. Pijanowski, B.C., A. Farina, S.H. Gage, S.L. Dumyahn & B.L. Krause. 2011a. What is soundscape ecology? An introduction and overview of an emerging new science. Landscape Ecol., 26: 1213-1232. Pijanowski, B.C., L.J. Villanueva-Rivera, S.L. Dumyahn, A. Farina, B.L. Krause, B.M. Napoletano, S.H. Gage & N. Pieretti. 2011b. Soundscape ecology: the science of sound in the landscape. Bioscience, 61(3): 203-216. Radford, C.A., A.G. Jeffs, C.T. Tindle & J.C. Montgomery. 2008. Resonating sea urchin skeletons create coastal choruses. Mar. Ecol. Prog. Ser., 362: 37-43. Radford, C.A., J.A. Stanley, S.D. Simpson & A.G. Jeffs. 2011. Juvenile coral reef fish use sound to locate habitats. Coral Reefs, 30: 295-305. Radford, C.A., J.A. Stanley, C.T. Tindle, J.C. Montgomery & A.G. Jeffs. 2010. Localized coastal habitats have distinct underwater sound signatures. Mar. Ecol. Prog. Ser., 401: 21-29. Staaterman, E., A.N. Rice, D.A. Mann & C.B. Paris. 2013. Soundscapes from a Tropical Eastern Pacific reef and a Caribbean Sea reef. Coral Reefs, 32: 553-557. Staaterman, E., C.B. Paris, H.A. DeFerrari, D.A. Mann, A.N. Rice & E.K. D’Alessandro. 2014. Celestial patterns in marine soundscapes. Mar. Ecol. Prog. Ser., 508: 17-32. Stanley, J.A., C.A. Radford & A.G. Jeffs. 2012. Location, location, location: finding a suitable home among the noise. Proc. Biol. Sci., 279: 3622-3631. Vermeij, M.J.A., K.L. Marhaver, C.M. Huijbers, I. Nagelkerken & S.D. Simpson. 2010. Coral larvae move toward Reef Sounds. PloS ONE, 5: e10660. Chilean coastal underwater soundscape Wall, C.C., R.A. Rountree, C. Pomerleau & F. Juanes. 2014. An exploration for deep-sea fish sounds off Vancouver Island from the Neptune Canada ocean observing system. Deep-Sea Res, I, 83: 57-64. Received: 18 May 2015; Accepted: 6 August 2015 997 Lat. Am. J. Aquat. Res., 43(5): 998-1010, 2015 SSR-based genetic diversity and differentiation in Mytilus chilensis DOI: 10.3856/vol43-issue5-fulltext-20 9981 Short Communication Heterologous microsatellite-based genetic diversity in blue mussel (Mytilus chilensis) and differentiation among localities in southern Chile María Angélica Larraín1, Nelson F. Díaz2, Carmen Lamas2, Carla Uribe2 Felipe Jilberto2 & Cristián Araneda2 1 Departamento de Ciencia de los Alimentos y Tecnología Química Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile Sergio Livingstone 1007 Independencia, Santiago, Chile 2 Departamento de Producción Animal, Facultad de Ciencias Agronómicas, Universidad de Chile Corresponding author: María Angélica Larraín ([email protected]) ABSTRACT. Mussels (Mytilus spp.) are one of the most cultivated and commercialized bivalves in southern Chile; culture is currently supplied almost entirely from wild-caught seed obtained from relatively few collection centers. The genetic diversity and differentiation of the blue mussel in southern Chile was investigated by sampling six locations: one natural bank and five seed collection centers. Nine polymorphic microsatellite (SSR) loci were genotyped (Mgu1, Mgu3, MT203, MT282, Mg15, Mg56, Med737, MIT02 and MGE005). We found 75 different alleles, six of which were private alleles. Of the analyzed loci, 45 of 54 tests performed deviated from Hardy-Weinberg equilibrium after sequential Bonferroni correction (P < 0.05), revealing significant heterozygote deficiencies. The polymorphic information content (PIC) ranged from 0.322 (MGE005) to 0.893 (Mgu1). Despite the long distance between some sampling sites (up to 1360 km), genetic differentiation among the sites was low (FST = 0.043, P < 0.0001). The Bayesian cluster analysis (STRUCTURE) indicated two probable clusters, while the non-parametric cluster analysis (AWclust) identified two to four clusters. Both analyses showed a high level of admixture within clusters. Our results indicate that blue mussels in southern Chile show lower genetic diversity than in other countries, low inbreeding levels, and limited genetic differentiation among locations. Keywords: Mytilus, mussels, genetic diversity, genetic differentiation, microsatellites, southern Chile. Diversidad genética del mejillón (Mytilus chilensis) y diferenciación entre localidades del sur de Chile usando marcadores microsatélites heterólogos RESUMEN. Los mejillones (Mytilus spp.) constituyen unos de los bivalvos más cultivados y comercializados en el sur de Chile. Su cultivo está actualmente abastecido completamente con semillas obtenidas desde el medio natural, de relativamente pocos centros de captación. La diversidad y diferenciación genética de los mejillones en el sur de Chile fue investigada muestreando seis lugares, un banco natural y cinco centros de captación de semilla. Se genotiparon nueve loci microsatélite (SSR) polimórficos (Mgu1, Mgu3, MT203, MT282, Mg15, Mg56, Med737, MIT02 y MGE005). Se encontraron 75 alelos diferentes, seis de ellos fueron alelos privados. En los loci analizados, 45 de los 54 test realizados mostraron desviación significativa (P < 0,05) del equilibrio de Hardy-Weinberg después de la corrección secuencial de Bonferroni, revelando un significativo déficit de heterocigotos. El contenido de información polimórfica (PIC) varió entre 0,322 (MGE005) y 0,893 (Mgu1). A pesar de la gran distancia entre algunos sitios de muestreo (hasta 1.360 km), la diferenciación genética entre ellos fue baja (FST = 0,043; P = 0,00). El análisis Bayesiano de agrupamiento (STRUCTURE) indicó que la estructura poblacional más probable consiste en dos grupos, en tanto el análisis de agrupamiento no paramétrico (AWclust) identificó entre dos y cuatro grupos, ambos análisis mostraron un alto nivel de mezcla dentro de los grupos. Estos resultados indican que los mejillones del sur presentan menor diversidad genética que en otros países, baja endogamia y diferenciación genética entre localidades. Palabras clave: Mytilus, mejillones, diversidad genética, diferenciación genética, microsatélites, sur de Chile. __________________ Corresponding editor: Cristian Aldea 2 999 Latin American Journal of Aquatic Research Mussels from the genus Mytilus, widely used for human consumption, are among the most cultivated and marketed bivalves. Chilean mussel culture yielded 10.8% of the world's Mytilidae production in 2012 (FAO, 2015). The distribution range for this species extends along the Chilean coast from Arauco (35ºS) to Cape Horn (55ºS) (Hernández & González, 1976), but nearly 100% of production comes from Chiloé Island and the mainland in the 41-44ºS region (SERNAPESCA, 2015). The name Mytilus chilensis (Hupé, 1854) was initially given to the native Chilean blue mussel, but the names M. edulis chilensis (Toro, 1998) and M. galloprovincialis chilensis (Cárcamo et al., 2005) were later proposed. Also, the species M. galloprovincialis described in the coasts of Chile was found to be distinct from the endemic Mytilus according to various molecular evidence (Tarifeño et al., 2005; Toro et al., 2005; Astorga & Toro, 2010), other authors (Westfall & Gardner, 2010) reported that the blue mussel now found in Chile is a mix of native Southern-hemisphere and introduced Northern-hemisphere M. galloprovincialis and M. edulis and their respective hybrids. Borsa et al. (2012) proposed the taxonomic status M. galloprovincialis planulatus and M. edulis platensis for these species, respectively. Since 2013, the WoRMS no longer recognizes the name Mytilus chilensis Hupé, 1854 (Boxshall et al., 2014) for the native Chilean smooth-shelled mussel, replacing it with the name Mytilus edulis platensis d'Orbigny, 1842 (Borsa et al., 2012). However, the name Mytilus chilensis is still used commercially, in statistics, in certifications, and on food product labels (GAA, 2013; FAO, 2015), and also by authors (Gazeau et al., 2013; Riisgard et al., 2013; Astorga, 2014; Larraín et al., 2014; Oyarzún et al., 2014; Ouagajjou & Presa, 2015). Moreover, there is evidence suggesting that M. chilensis is a valid, distinct species within the genus based on the strong genetic and reproductive differences versus the native Chilean mussel, M. galloprovincialis (Mediterranean and Atlantic populations) and M. edulis found when these taxa were evaluated with a 54-SNP panel developed by Zbawicka et al. (2014) as marker for Mytilus taxa (R. Wenne pers. comm.), with microsatellite markers (Ouagajjou et al., 2011), mitochondrial cytochrome oxidase I gene (COI) (Seguel, 2011), and sperm morphology (Oyarzún et al., 2014). Therefore, we use the name M. chilensis for the native and predominant blue mussel species that inhabits the Chilean coast. The long larval phase of the Mytilus lifecycle extends its dispersal capacity to large geographic areas, increasing gene flow, preventing differentiation among populations, and preserving high levels of diversity within populations (Toro et al., 2006). Currently, aquaculture farms are supplied solely with seed collected from the wild in the area of the Reloncaví estuary and Chiloé Island (Bagnara & Maltraín, 2008). In 2012-2013 a significant decrease in seed supply from the collection centers was reported for the zone. Understanding the genetic diversity and differentiation of economically-important species is fundamental for supporting management and conservation programs, enhancing production, and exploring the possibility of developing DNA-based traceability systems using allocation algorithms. In Chile, studies of Mytilus genetic diversity and differentiation have been performed using RAPDs and allozyme markers (Toro et al., 2004, 2006), producing no evidence of discrete stocks, with the possible exception of a Magallanes population (Punta Arenas 53ºS). Microsatellite markers are an important tool used to assess genetic diversity levels and population structures in marine species (Liu & Cordes, 2004); these markers have been applied to the Mytilidae family for species such as Perumytilus purpuratus (Perez et al., 2008; Briones et al., 2013), M. galloprovincialis (Diz & Presa, 2008, 2009), M. edulis, and M. trossulus (Kijewski et al., 2009; Shields et al., 2010). In Chilean blue mussels, SSR have been used by Vidal et al. (2009) and Ouagajiou et al. (2011) in cross-species amplification and allelic variation assessment, respectively, on a limited number of individuals from a single location, but to date there are no published studies of genetic diversity or differentiation among locations using this tool. The current study aims to investigate the genetic diversity and differentiation of Mytilus chilensis in southern Chile using nine heterologous SSR loci. This survey complements previous population studies conducted in the region based on allozyme and RAPDs analysis, with more informative SSR markers. Mussel samples (n = 50 by location) were collected in southern Chile from three zones: 1) Reloncaví (Quillaipe: 1-QI, Pichicolo: 1-PI, Caleta La Arena: 1LA, and Canutillar: 1-CN), 2) Chiloé (Canal ColditaPiedra Blanca: 2-CB), and 3) Magallanes (Isla Peel: 3IP). In zones 1 and 2, where mussel aquaculture activities are carried out, we sampled seed collection centers, and in zone 3, the source was a natural bank. Detailed information about sampling, DNA extraction, genus, and species identification can be found in Larraín et al., (2012, 2014). Only M. chilensis individuals, identified according to designation at the RFLP-PCR Me 15-16 Aci I marker (Inoue et al., 1995; Santaclara et al., 2006), were used for microsatellite analysis. Nine SSR loci were genotyped. The repeat motifs obtained from GenBank sequences by accession number were: mononucleotide (Mg15) (Cruz et al., SSR-based genetic diversity and differentiation in Mytilus chilensis 2005), perfect dinucleotide (Mgu3, MT203, MT282, MIT02, MGE005) (Presa et al., 2002; Gardeström et al., 2007; Yu & Li, 2007; Vidal et al., 2009), compound dinucleotide (Mgu1, Med737) (Presa et al., 2002; Lallias et al., 2009), and complex (Mg56) (Cruz et al., 2005). Detailed information about primers and PCR conditions used to amplify eight of the motifs (Mgu1, Mgu3, MT203, MT282, Mg15, Mg56, Med737 and MIT02) are described in Larraín et al. (2014). The other locus used in this work was MGE005 (Yu & Li, 2007). For this last locus, primers (F: 5´-AGACCAAGGTA TTGCAACCATGTG-3 and R: 5´-TCGAAAGCATG GTACCTGGTCA-3´) were obtained using AmplifX (http://crn2m.univ-mrs.fr/recherche/brue/jullien(http://crn2m.univ-mrs.fr/recherche/brue/jullien-nicolas/ programmation/amplifx) and the Primer Blast NCBI utility (http://www.ncbi.nlm.nih.gov/tools/ primer-blast/). The primers were commercially synthesized by Integrated DNA technologies Inc. (IDT) (Singapore). The PCR thermal profile to amplify the MGE005 locus was 95°C for 5 min, followed by 35 cycles at 95°C (1 min), 67ºC (30 s), 72°C (50 s), and a final 10-min extension step at 72°C. PCR amplification was carried out in a 15-µL reaction mixture containing 1.5 L of 10x PCR buffer, 1.5 mM MgCl2, 100 M each of dNTP, 0.3 M of each primer, 0.5 U Taq DNA Polymerase (RBC Bioscience®), and 40 ng of DNA. A negative control with template DNA replaced by water was performed for each set of amplifications. To evaluate amplification, PCR products were visualized on an agarose gel (1.8%) in TBE buffer with 10 mg mL-1 of ethidium bromide under ultraviolet light. For genotyping, polyacrylamide gels (6%) with silver staining were used to resolve alleles (Larraín, 2012); for every gel, the size of amplified fragments was estimated from a 10-bp DNA ladder (Invitrogen®) or HyperLadder V (Bioline®). The Excel add-in MS tools (Park, 2001) and CONVERT software (Glaubitz, 2004) were used to reformat diploid genotypic data. MICRO-CHECKER (Van Oosterhout et al., 2004) was used to test for the presence of null alleles, stuttering, and large allele dropout. Genetic diversity was determined by the observed number of alleles per locus (Na), observed (Ho) and expected (He) heterozygosities, polymorphic information content (PIC), and the presence of private alleles, using MS tools (Park, 2001). Genepop 4.0.10 (Raymond & Rousset, 1995; Rousset, 2008) was used to test genotypic linkage disequilibria (LD) between each pair of loci, to evaluate genotypic distributions for conformation to Hardy-Weinberg equilibrium (HWE), and to estimate Wright's fixation indices (FIS, FST, and FIT) according to Weir & Cockerham (1984). Exact Pvalues were estimated by the Markov chain method (Guo & Thompson, 1992), using default software conditions. Sequential Bonferroni correction was used 3 1000 for multiple tests (Holm, 1979; Rice, 1989). The relatedness index rxy (Queller & Goodnight, 1989) for each pair of individuals was obtained using Identix software (Belkhir et al., 2002). Genetic differentiation among locations was determined with Genetix 4.05 (Belkhir et al., 1996) to estimate pairwise FST and its statistical significance and to perform a three-dimensional factorial correspondence analysis (3D-FCA). The Mantel test (Mantel, 1967) was performed to test an isolation-by-distance model of genetic differentiation. Correlation coefficient (r) calculations were performed with Genetix 4.05, and the significance of the associations was tested with 10,000 iterations. We compared the genetic distance matrices (FST / (1-FST)) with the logarithm of the minimal geographic distance estimated by the coastline (Abbott et al., 2013), as recommended for a two-dimensional habitat (latitude and longitude) (Rousset, 2008). The genetic structure was investigated with parametric-with -STRUCTURE 2.3.4 (Pritchard et al., 2000)- and non-parametric AWclust (Gao & Stramer, 2008)- frameworks. The Bayesian approach (STRUCTURE) was performed using the standard burn-in period length (50,000) and number of MCMC reps after burn-in (100,000) (Falush et al., 2007), achieving convergence with our data. Ten repeated runs were performed, selecting K = 6, the admixture ancestry, and the correlated allele frequency models. The number of clusters (K) that best fit the data was inferred using Delta K values as described by Evanno et al. (2005) and calculated using the STRUCTURE Harvester webpage (Earl & von Holdt, 2012). The R package AWclust -allele sharing distance and Ward's minimum variance hierarchical clustering(Gao & Starmer, 2008) was used, converting the multiallelic SSR data according to Wei et al. ( 2013). Null alleles were present in all locations for loci Mgu1, Mgu3, MT203, Mg15, Mg56, and MIT02 and in some locations for loci MT282 and Med737 but not detected in any location for locus MGE005. The frequency of non-amplifying individuals (putative null allele homozygotes) was less than 5% for all loci, and thus all were used in further analysis (Dąbrowski et al., 2014). All loci showed common allele distributions among sites. Six private alleles, i.e., alleles unique to a single site, were found at low frequency (0.01-0.02) in the seed collection centers Pichicolo (1-PI) and Caleta La Arena (1-LA) at locus Mgu3, Canal Coldita-Piedra Blanca (2-CB) at locus Mg56, Quillaipe (1-QI) at locus Med737, and Quillaipe (1-QI) and Canutillar (1-CN) at locus MGE005 (Annex 1). A total of 75 alleles were detected at the nine loci among the analyzed individuals (Table 1). All loci were polymorphic in all locations as the frequency of the most common allele did not 41001 Latin American Journal of Aquatic Research Table 1. Global genetic diversity estimators by locus in samples (n = 300) of blue mussel (Mytilus chilensis) in southern Chile using nine SSR loci. Na: number of alleles, Ho: the observed heterozygosity, He: the expected heterozygosity, PIC: polymorphic information content and the fixation indices FIS, FST, FIT, according to Weir & Cockerham (1984). Locus Mgu1 Mgu3 MT203 MT282 Mg15 Mg56 Med737 MIT02 MGE005 Global Na 15 6 10 4 4 11 10 5 10 75 Ho 0.407 0.097 0.453 0.543 0.416 0.470 0.483 0.365 0.320 0.395 He 0.903 0.610 0.782 0.616 0.694 0.760 0.756 0.617 0.330 0.674 exceed 0.95; average number of alleles per locus was 8.3 ± 3.8, ranging from four for MT282 and Mg15 in all locations to 15 for Mgu1 in Quillaipe (1-QI) and Pichicolo (1-PI) (Annex 2). PIC values ranged from 0.322 at locus MGE005 to 0.893 at locus Mgu1 (Table 1). With the exception of locus MGE005, which was moderately informative, all other loci were highly informative (PIC > 0.5) (He et al., 2012). Ho ranged from 0.097 (Mgu3) to 0.543 (MT282), while He values ranged from 0.330 (MGE005) to 0.903 (Mgu1) (Table 1). Significant deviations from HWE were observed in 45 of the 54 tests (9 loci × 6 locations), performed after correction for multiple testing (Holm, 1979; Rice, 1989). Significant deviations corresponded to positive FIS values observed in various loci, indicating heterozygote deficiencies. Tests for linkage disequilibrium (LD) showed no significant deviations for any of the 216 tests performed (36 locus combinations × 6 locations) after sequential Bonferroni correction for multiple tests (Holm, 1979; Rice, 1989). Although average relatedness (rxy) between pairs of individuals from the same site was significantly higher than between pairs of randomly-mixed individuals from different locations, at -0.019 ± 0.0013 and -0.137 ± 0.0009, respectively (P < 0.0001), neither value was significantly different from zero. Pairwise FST values among all six locations indicate (Table 2) that the highest FST (0.1112) value was between Canal Coldita-Piedra Blanca (2-CB) and Caleta La Arena (1-LA). Fourteen of the 15 tests (P < 0.05) showed significant pairwise FST values after correction for multiple comparisons (Holm, 1979; Rice, 1989). The global FST value indicates that 4.3% of the total allele frequency variance lies among sample sites and is highly significant (P < 0.0001), while 95.7% is explained by the variation within sites. The first three PIC 0.893 0.540 0.757 0.543 0.630 0.725 0.721 0.544 0.322 0.631 FIS 0.542 0.802 0.413 0.111 0.395 0.369 0.319 0.411 0.032 0.393 FST 0.021 0.227 0.015 0.010 0.012 0.026 0.073 0.000 0.000 0.043 FIT 0.551 0.847 0.422 0.119 0.403 0.385 0.369 0.409 0.031 0.419 components of the 3D-FCA (Fig. 1) account for 81.78% of the total variation in multilocus genotypes, 43.38% of which is explained by Axis 1, which separates Caleta La Arena (1-LA) from the other five sites, 22.18% by Axis 2, which separates Quillaipe (1QI) and Canal Coldita-Piedra Blanca (2-CB) from the other sites, and 16.22% by Axis 3, which separates the most southern sample (3-IP). The Mantel test showed no significant correlation (r = -0.0130, P = 0.3610) between genetic and geographic distance. Bayesian clustering analysis indicated that K = 2 (Fig. 2a) is the most likely value for inferred Mytilus chilensis clusters in the zone. The analysis showed that individuals from 1-LA were grouped together in cluster II and 2-CB in cluster I, with high average proportions of membership at 0.966 and 0.824, respectively (Table 3a), coinciding with the separation of these sites as shown by 3D-FCA. All other sites appeared to be highly admixed with individuals sharing membership between both clusters. The gap analysis from AWclust showed 3 clusters, by a narrow margin with widely overlapping error bars for K = 2 and 4 (Fig. 2b). As in the STRUCTURE analysis, a large proportion (0.72) of 1-LA individuals were grouped into a single cluster (cluster III) (Table 3b). Microsatellites are one of the most informative genetic markers at the intra-specific level, used extensively to study marine species. However, in Mytilus, a relatively low number of SSR markers have been described compared with other aquaculture species such as salmon or trout, which have more than 2000 mapped SSR markers (Guyomard et al., 2012). Genetic diversity is essential because it allows for population and species survival and adaptation to changing environmental conditions (Mohanty et al., 2014). The total of 75 alleles detected after genotyping SSR-based genetic diversity and differentiation in Mytilus chilensis 10025 Table 2. Pairwise FST values between the blue mussel’s (Mytilus chilensis) locations in southern Chile. Zone and location codes: 1) Reloncaví (Quillapie: 1-QI, Pichicolo: 1-PI, Caleta La Arena: 1-LA and Canutillar: 1-CN), 2) Chiloé (Canal Coldita-Piedra Blanca: 2-CB), and 3) Magallanes (Isla Peel: 3-IP). *P < 0.05 after correction with sequential Bonferroni correction. 1-QI 1-PI 1-LA 1-CN 2-CB 1-PI 0.0191* 1-LA 1-CN 0.0390* 0.0305* 0.0650* 0.0049 0.0712* 2-CB 0.0787* 0.0255* 0.1112* 0.0196* 3-IP 0.0323* 0.0146* 0.0740* 0.0245* 0.0250* Figure 1. Three-dimensional factorial correspondence analysis plot (3D-FCA) for the six blue mussel (Mytilus chilensis) populations in southern Chile. Sample codes are indicated in Table 2. all nine SSR loci across the six sampling locations suggests lower genetic diversity than in other SSR studies of Mytilus (Diz & Presa, 2009; Shields et al., 2010). This is also evident from the global levels of observed and expected heterozygosities (Ho: 0.395 and He: 0.674) (Table 1). For example, in locus Mgu3, twelve alleles were found in Spain (Diz & Presa, 2009) and in a hybrid zone in Canada (Shields et al., 2010), while in this study we found only six alleles. The genetic diversity range (0.330 He 0.903) in Mytilus chilensis from the zone studied was wider than observed in M. galloprovincialis from Galicia, Spain (0.72 He 0.80) as assessed with six SSR loci (Diz & Presa, 2008). But the observed heterozygosity in this study exceeds that reported for allozymes in the same species and area (Ho = 0.29) (Toro et al., 2006), as expected due to the highly polymorphic nature of SSR. Deviations from HWE as shown by positive FIS values observed at several loci, at many sites, revealed heterozygote deficiencies. Toro et al. (2006) also reported widespread heterozygote deficiencies in population STRUCTURE studies in the same species and area using allozymes. Null alleles cause heterozygous individuals to appear homozygous if they carry a visible allele and the null allele (Brookfield, 1996). This is the best-known reason for underestimation of heterozygosity with microsatellites (Shields et al., 2010) and a common phenomenon in marine bivalve population genetics (Chapuis & Estoup, 2007). Although we used only loci with <5% of nonamplifying individuals (putative null allele homozygotes) (Dąbrowski et al., 2014), null alleles could be a reason for the heterozygote deficiencies observed. The heterologous nature of the microsatellites used in this study -SSR developed for M. edulis, M. trossulus, and M. galloprovincialis were applied to Chilean blue mussels- could explain the presence of null alleles. Using the SSR developed in M. chilensis, not available 61003 Latin American Journal of Aquatic Research Figure 2. Number of clusters identified by a) Parametric approach implemented in STRUCTURE. Plot of the Delta K calculated as ∆𝐾 = 𝑚𝑒𝑎𝑛 ǀ𝐿´´(𝐾)ǀ . 𝑠𝑑 [𝐿(𝐾)] The modal value of this distribution is the true K or the uppermost level of structure, b) non-parametric approach implemented in AWclust. Plot of the gap statistics between the observed and expected Wk results for K = 1-6 in M. chilensis. The largest gap indicates the most appropriate number of clusters for the data. until after the completion of this experimental work, may have reduced the frequency of null alleles found (Ouagajjou et al., 2011). However, these species are genetically and phenotypically close in both hemispheres, as evidenced by the controversy over the taxonomic status of the Chilean blue mussel and the widely-described presence of null alleles in Mytilus SSR (Presa et al., 2002; Gardeström et al., 2007; Yu & Li, 2007; Shields et al., 2010; Ouagajjou et al., 2011). Also, in other studies in the literature, correcting allele frequencies for null alleles between Mytilus populations did not change the results of statistical tests to estimate population differentiation (Gardeström et al., 2007; Diz & Presa, 2008) or had a only minor effect on the population differentiation estimates, genetic distance determinations, and allocation of individuals to populations (Hauser et al., 2006; Chapuis & Estoup, 2007). Given the above, along with the consideration that null alleles may not be the only reason for the observed heterozygote deficiencies, we decided not to correct the allele frequencies. Other possible reasons for heterozygote deficiencies found in Mytilus population studies are, among others, inbreeding, aneuploidy, molecular imprinting, and selection (Beaumont, 1991; Toro et al., 2006; Diz & Presa, 2009). Although the relatedness between pairs of individuals from the same site was significantly higher than between individuals from different sites, in both cases relatedness was no higher than expected by chance (data not shown), providing no evidence of mating between related individuals (inbreeding). The results of the microsatellite analyses revealed a common distribution of alleles between blue mussel locations in southern Chile. The global FST (0.040) obtained in this survey was low but significant, and it is within the range reported by Toro et al. (2004) using allozymes (FST = 0.03), although it is higher than the value reported by Cárcamo et al. (2005), also using allozymes (FST = 0.012), and those found in mussel populations on the Iberian Peninsula (FST = 0.0240 and 0.0122) using microsatellites. However, a greater differentiation between localities cannot be discounted due to cryptic allelic homoplasy described for SSR markers (Diz & Presa, 2008, 2009). Although individuals taken from seed collection centers in zones 1 and 2 are intended for transport to grow-out centers and never will spawn in the place where they were recruited, they account for the composition of the fixed individuals in each location and may be informative regarding the location's genetic diversity and differentiation. Despite the geographical barriers of the coastline (fjords) and the considerable geographical distance between the most southern sample from Isla Peel (3-IP) in zone 3 and the Reloncaví and the Chiloé zones (zones 1 and 2 respectively), the mussel's reproductive system (external fertilization), the prolonged pelagic larval stage of this species (40-45 days) (Toro et al., 2004), the intense aquaculture activities in the Reloncaví and Chiloé zones (transportation of juveniles from seed collection centers to ongrowing centers), and the ocean currents (Cape Horn and Chilean Coastal Current) (Strub et al., 1998) promote dispersal, preventing higher levels of genetic differentiation. Furthermore, in studies of other bivalves in the area with lower production levels than Mytilus chilensis, such as the clam (Venus antiqua) and the ribbed mussel (Aulacomya atra) (Mena et al., 2001), higher genetic differentiation values were found using allozymes (FST = 0.107 and 0.147, respectively). This finding led us to infer that some of the genetic homogeneity between locations in the current study could be attributed to the 10047 SSR-based genetic diversity and differentiation in Mytilus chilensis Table 3. Number of blue mussel (Mytilus chilensis) individuals in each location (n) and proportion of membership of individuals from each location to each of: a) the two clusters inferred by STRUCTURE, and b) the three clusters inferred by AWclust. Sample codes are indicated in Table 2. a Locations 1-QI 1-PI 1-LA 1-CN 2-CB 3-IP STRUCTURE-inferred clusters n I II 50 0.391 0.609 50 0.623 0.377 50 0.034 0.966 50 0.731 0.269 50 0.824 0.176 50 0.634 0.366 effect of extensive seed transfer, as reported in Galicia (Diz & Presa, 2009). The extent of pairwise genetic differentiation among the six sampled locations was small, but pairwise FST showed significant allelic differentiation, revealing unpatterned genetic heterogeneity among the local population, or genetic patchiness. This effect results in geographically close populations that may differ genetically as much as very distant populations, as has been reported in other marine organisms (Larson & Julian, 1999; Appleyard et al., 2002). The numbers of clusters inferred from the parametric (K = 2) and non-parametric methods (K = 3) were different; however, they were not in conflict because the gap statistic to determine the discrete number of clusters in AWclust gave widely overlapping error bars for K = 2, 3, and 4, providing a better resolution of the population structure (Fig. 2b). The parametric clustering approach in STRUCTURE provided more information (i.e., about the probability an individual's membership in each cluster), but it relies on assumptions like HWE that were not always met during this study. Therefore, the non-parametric method for population structure analysis is more appropriate. According to Gao & Starmer (2008), the two methods can be complementary in structure analysis. Our results for blue mussels using nine microsatellite loci indicate low inbreeding levels and lower levels of genetic diversity in Chile than in Spain or Canada; this latter is recognized as a hybrid zone, so higher levels of allelic richness and heterozygosity are expected. Furthermore, we found low but significant genetic differentiation among locations in southern Chile. These findings may be partly explained by reproduction conditions, prolonged pelagic larval stage, oceanographic conditions, and intense Chilean blue mussel aquaculture in the region. b AWclust-inferred clusters Locations 1-QI 1-PI 1-LA 1-CN 2-CB 3-IP n 50 50 50 50 50 50 I 0.26 0.42 0.08 0.32 0.48 0.26 II 0.16 0.24 0.20 0.46 0.36 0.36 III 0.58 0.34 0.72 0.22 0.16 0.38 ACKNOWLEDGEMENTS This research was supported by CONICYT, FONDECYT/Regular N°1130302, and Universidad de Chile (Vice-Rectoría de Investigación-Proyecto Domeyko-Alimentos). 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Allele frequencies for nine SSR loci genotyped in blue mussels (Mytilus chilensis) from six locations in southern Chile. Zone and location codes: 1) Reloncaví (Quillaipe: 1-QI, Pichicolo: 1-PI, Caleta La Arena: 1-LA and Canutillar: 1CN), 2) Chiloé (Canal Coldita-Piedra Blanca: 2-CB), and 3) Magallanes (Isla Peel: 3-IP). Allele size [bp] Location Locus Mgu1 1-QI 1-PI 1-LA 1-CN 2-CB 3-IP 115 151 4.00 6.00 153 155 163 171 173 175 177 181 187 189 6.00 21.00 6.00 2.00 6.00 10.00 11.00 13.00 7.00 2.00 197 217 1.00 5.00 2.00 2.00 1.00 - 6.00 2.00 8.00 3.00 Mgu3 225 141 - 2.00 1.00 - 2.00 - - MT203 143 31.00 147 51.00 151 157 9.00 159 9.00 178 36.00 62.00 1.00 74.49 36.00 47.00 23.47 48.00 1.00 1.02 1.00 3.00 1.02 45.00 25.00 34.00 184 6.00 188 30.00 13.00 25.00 12.00 6.00 6.00 21.00 17.00 18.00 12.00 18.00 MT282 Mg15 17.00 3.00 2.00 2.00 6.00 3.00 14.00 3.00 8.00 12.00 24.00 9.00 18.00 19.00 17.00 8.00 8.00 7.00 26.00 12.00 3.00 13.00 4.00 1.00 1.00 6.00 3.00 3.00 4.00 6.00 4.00 2.00 2.00 10.00 13.00 16.00 2.00 12.00 14.00 24.00 15.00 11.00 20.00 8.00 11.00 10.00 5.00 3.00 4.00 6.00 6.00 1.00 2.00 - 192 2.00 1.00 - 194 198 6.00 7.00 6.00 4.00 10.00 202 206 7.00 3.00 11.00 1.00 216 220 3.00 - 3.00 1.00 335 347 353 381 115 120 28.00 18.00 49.00 5.00 9.78 38.04 1.00 4.00 5.00 - 83.00 58.00 15.00 33.00 1.00 7.00 1.00 2.00 50.00 44.00 6.00 - 7.00 7.00 4.00 8.00 10.00 10.00 1.00 11.00 3.00 7.00 4.00 10.00 1.00 5.00 9.00 4.00 4.00 - 2.00 - 2.00 1.00 41.00 33.00 33.00 37.00 40.00 14.00 2.00 10.00 5.00 17.00 41.00 60.00 52.00 55.00 41.00 4.00 5.00 5.00 3.00 2.00 2.08 3.06 7.14 2.04 3.00 31.25 32.65 29.59 28.57 43.00 1009 12 Latin American Journal of Aquatic Research Continuation Allele size [bp] Location Locus Mg56 Med737 MIT02 MGE005 1-QI 1-PI 1-LA 1-CN 2-CB 3-IP 123 10.87 135 41.30 247 294 1.04 301 7.29 30.21 35.71 36.73 39.80 29.00 36.46 28.57 26.53 29.59 25.00 1.00 6.12 8.00 2.04 6.00 2.00 4.08 7.00 8.16 1.00 3.00 337 2.08 344 26.04 351 45.83 372 3.13 399 425 4.17 441 10.42 464 122 1.00 134 - 9.18 4.00 5.10 11.00 9.00 32.65 26.00 41.84 51.00 30.00 24.49 46.00 26.53 17.00 32.00 2.04 1.00 5.10 3.00 2.00 1.02 1.02 1.00 1.00 3.06 3.00 1.02 3.00 4.00 13.27 4.00 8.16 4.00 17.00 4.08 1.00 1.02 2.00 1.00 1.00 3.00 - 140 57.00 142 4.00 146 18.00 152 8.00 164 8.00 168 2.00 174 2.00 184 197 4.00 221 7.00 40.00 52.00 51.00 13.00 19.00 7.00 4.00 4.00 1.00 35.00 21.00 22.00 35.00 8.00 3.00 2.00 3.00 2.00 6.00 12.00 11.00 14.00 29.00 37.00 4.00 2.00 1.00 13.00 12.00 3.00 4.00 4.00 13.00 2.00 2.00 4.00 1.00 2.00 6.00 7.14 7.00 14.00 3.00 5.00 10.20 2.00 227 51.00 237 2.00 243 36.00 113 2.00 119 2.00 122 3.00 125 4.00 128 2.00 134 5.00 137 79.00 51.00 4.00 30.00 2.00 3.00 7.00 2.00 82.00 140 143 149 2.00 1.00 - 52.00 4.00 39.00 3.00 5.00 1.00 3.00 83.00 52.00 39.80 45.00 2.04 3.00 37.00 40.82 43.00 1.00 3.00 5.00 7.00 3.00 4.00 2.00 3.00 11.00 3.00 2.00 77.00 83.00 85.00 2.00 4.00 3.00 2.00 1.00 1.00 1.00 3.00 2.00 - 1.00 - 1010 13 SSR-based genetic diversity and differentiation in Mytilus chilensis Annex 2. Diversity parameters for nine SSR loci analyzed in six mussel locations (Mytilus chilensis) from southern Chile. Sample codes are indicated in Annex 1. Note: The number of alleles (Na), the number of private alleles (Ap), the observed heterozygosity (Ho), the expected heterozygosity (He), and the fixation index Fis according to Weir & Cockerham are provided for each locus and sample site. * Significant departures from Hardy-Weinberg expectations are corrected with sequential Bonferroni correction. Locus/Location Mgu1 A(Ap) Ho He Fis (W&C) Mgu3 A(Ap) Ho He Fis (W&C) MT203 A (Ap) Ho He Fis (W&C) MT282 A (Ap) Ho He Fis (W&C) Mg15 A (Ap) Ho He Fis (W&C) Mg56 A (Ap) Ho He Fis (W&C) Med737 A (Ap) Ho He Fis (W&C) MIT02 A (Ap) Ho He Fis (W&C) MGE005 A (Ap) Ho He Fis (W&C) Mean acrossloci ± SD A (Ap) Ho He Fis (W&C) 1-QI 1-PI 1-LA 14(0) 0.500 0.902 0.448* 14(0) 0.300 0.886 0.664* 12(0) 0.560 0.871 0.360* 4(0) 0.160 0.634 0.750* 4(1) 0.040 0.491 0.919* 9(0) 0.380 0.769 0.508* 9(0) 0.420 0.729 0.426* 4(0) 0.420 0.653 0.359* 4(0) 0.560 0.649 0.139* 2-CB 3-IP 13(0) 0.340 0.883 0.617* 12(0) 0.500 0.888 0.440* 13(0) 0.240 0.866 0.725* 5(1) 0.200 0.553 0.641* 4(0) 0.041 0.394 0.897* 4(0) 0.040 0.291 0.864* 4(0) 0.100 0.555 0.821* 9(0) 0.440 0.830 0.473* 9(0) 0.420 0.817 0.488* 9(0) 0.500 0.717 0.305* 9(0) 0.560 0.753 0.259* 4(0) 0.600 0.563 -0.067 4(0) 0.480 0.649 0.263* 4(0) 0.413 0.671 0.387* 4(0) 0.396 0.685 0.425* 4(0) 0.490 0.690 0.293* 4(0) 0.469 0.709 0.341* 4(0) 0.347 0.679 0.492* 4(0) 0.380 0.674 0.439* 8(0) 0.521 0.710 0.269* 10(0) 0.469 0.807 0.421* 9(0) 0.460 0.712 0.357* 10(0) 0.408 0.743 0.453* 11(1) 0.380 0.698 0.458* 9(0) 0.580 0.775 0.254* 8(1) 0.634 0.595 0.245* 8(0) 0.706 0.650 0.152* 8(0) 0.673 0.630 0.378* 8(0) 0.675 0.628 0.499* 7(0) 0.764 0.719 0.269* 8(0) 0.792 0.758 0.371* 5(0) 0.280 0.769 0.543* 5(0) 0.300 0.729 0.530* 5(0) 0.400 0.830 0.313* 4(0) 0.320 0.817 0.463* 5(0) 0.449 0.717 0.328 5(0) 0.440 0.753 0.284 9(1) 0.320 0.373 0.143 7(0) 0.320 0.323 0.011 7(0) 0.280 0.381 0.092 6(1) 0.360 0.393 0.085 8(0) 0.340 0.310 -0.099 6(0) 0.300 0.275 -0.093 7.1 ± 3.3 0.386 ± 0.117 0.662 ± 0.141 0.406* 7.2 ± 3.4 0.378 ± 0.167 0.657 ± 0.167 0.410* 6.9 ± 2.5 0.426 ± 0.123 0.639 ± 0.170 0.313* 7.0 ± 3.2 0.369 ± 0.154 0.647 ± 0.170 0.426* 7.0 ± 2.9 0.413 ± 0.167 0.620 ± 0.200 0.332* 6.9 ± 3.1 0.398 ± 0.159 0.661 ± 0.175 0.369* 4(0) 0.580 0.534 -0.088 1-CN 4(0) 0.620 0.614 -0.009 14 Latin American Journal of Aquatic Research Lat. Am. J. Aquat. Res., 43(5): 1011-1018, 2015 DOI: 10.3856/vol43-issue5-fulltext-21 ISSR markers for Pterois species 1011 Short Communication The use of ISSR markers for species determination and a genetic study of the invasive lionfish in Guanahacabibes, Cuba Elizabeth Labastida1, Dorka Cobián2, Yann Hénaut3, María del Carmen García-Rivas4 Pedro P. Chevalier5 & Salima Machkour-M´Rabet1 1 Laboratorio de Ecología Molecular y Conservación, El Colegio de la Frontera Sur (ECOSUR) Av. Centenario km 5.5, C.P. 77014, Chetumal, Quintana Roo, México 2 Parque Nacional Guanahacabibes, Centro de Investigaciones y Servicios Ambientales (ECOVIDA) La Bajada, Municipio Sandino, Pinar del Río, Cuba 3 Laboratorio de Conducta Animal, El Colegio de la Frontera Sur (ECOSUR) Av. Centenario km. 5.5, C.P. 77014, Chetumal, Quintana Roo, México 4 Secretaría de Medio Ambiente y Recursos Naturales, Comisión Nacional de Áreas Naturales Protegidas (SEMARNAT-CONANP), Smza 86 Mza 2 Lote 4 Carretera Punta Sam, Puerto Juárez, Quintana Roo, México 5 Acuario Nacional de Cuba, 3ª y 62 Miramar, Playa, Ciudad Habana, Cuba Corresponding author: Salima Machkour-M'Rabet ([email protected]) ABSTRACT. The red lionfish (Pterois volitans) and devil fire-fish (Pterois miles) are invasive species that pose a threat to the biodiversity and stability of coral reefs in the Western Atlantic, Gulf of Mexico and Caribbean Sea. Species identification of lionfish is uncertain in some parts of Cuba, and research has mainly been focused on their biology and ecology. The principal aim of this study was to determine highly polymorphic markers (Inter Simple Sequence Repeat, ISSR) that could be used in research on lionfish population genetics in addition to confirming the presence of Pterois species in the Guanahacabibes National Park. The genetic profile or “fingerprint” of individuals collected in Mexico, formally identified as P. volitans, was compared with the genetic profile of specimens from Cuba. There were very few “diagnostic bands” and a high number of "common bands", demonstrating that the same species exists in both countries. Furthermore, Nei's genetic distance and the unrooted tree do not show significant differences between both localities. In light of these results, we can confirm the presence of P. volitans in the Guanahacabibes National Park, Cuba. This study demonstrates the functionality of ISSR as a molecular tool for species identification and their application for genetic population studies of this invasive fish species. Keywords: Pterois volitans, fish, fingerprint, ISSR, Caribbean Sea. Uso de marcadores ISSR para la determinación de especies y estudios genéticos del pez león, especie invasora en Guanahacabibes, Cuba RESUMEN. El pez león rojo (Pterois volitans) y el pez fuego diablo (Pterois miles) son especies invasoras que amenazan la biodiversidad y estabilidad de los arrecifes coralinos del Atlántico occidental, Golfo de México y Mar Caribe. La identificación del pez león sigue incierta en unas zonas de Cuba y la investigación se ha centrado principalmente en su biología y ecología. El propósito principal de este estudio fue determinar marcadores altamente polimórficos (secuencias repetidas inter simples, ISSR) útiles para estudios de genética poblacional del pez león y aplicarlos para determinar la especie de Pterois presente en el Parque Nacional Guanahacabibes. Se comparó el perfil genético de individuos colectados en México, formalmente identificados como P. volitans, con el perfil genético de especímenes de Cuba. Los perfiles genéticos mostraron un bajo número de “bandas diagnósticas” y un alto número de bandas comunes lo que demuestra que en ambos países está presente la misma especie. Por otra parte, los resultados de distancia genética de Nei y el árbol no enraizado no muestran ninguna diferencia significativa entre ambas localidades. Estos resultados confirman la presencia de P. volitans en el Parque Nacional Guanahacabibes, Cuba, y se demostró la funcionalidad de ISSR como herramienta molecular para la identificación de especies y su aplicación para estudios de genética poblacional de este pez invasor. Palabras clave: Pterois volitans, fingerprint, ISSR, peces, Mar Caribe. __________________ Corresponding editor: Patricio Arana 1012 Latin American Journal of Aquatic Research Invasive species are a major threat to marine ecosystems. They impact the ecosystem structure and function and have a negative effect on biodiversity (Costello et al., 2010; Ojaveer et al., 2014). During the last decade, considerable efforts were made to understand and eradicate one of the most important invasive predators in the Atlantic, the Indo-Pacific lionfish complex: the red lionfish Pterois volitans (Linnaeus, 1758) and the devil fire-fish Pterois miles (Bennett, 1828). The invasion has progressed rapidly since the first observation of lionfish in Florida in 1985 (Morris & Akins, 2009). Today, the species has invaded an area over 7 million km2 (Dahl & Paterson, 2014), including the eastern coast of the USA, Gulf of Mexico, Caribbean Sea (Schofield, 2009) and has extended their range throughout of the eastern coast of South America, mainly in Venezuela and Brazil (Fortunato & Avigliano, 2014; Ferreira et al., 2015). According to Sakai et al. (2001), the study of the genetic diversity and population structure of a new invasive species is essential as the obtained information may contribute to understanding the potential establishment and geographical dispersion of invasive species. This information could also play an important role in the development of appropriate strategies for the management of such species. Another fundamental aspect concerning invasive species is the correct identification of the introduced species and the determination of their origin (Le Roux & Wieczorek, 2009). An erroneous taxonomic classification may obscure accurate invasion history and preclude management strategies. Because of inter- and intraspecific variations, morphological identification often presents difficulties, whereas molecular markers can accurately, reliably and rapidly identify species as well as variants and cryptic taxa (Holland et al., 2004; Le Roux & Wieczorek, 2009; García-Morales & Elías-Gutiérrez, 2013). These examples show the efficacy and importance of molecular tools when carrying out research on invasive organisms, especially as taxonomic identification is a first important step towards developing effective control and management decisions (Le Roux & Wieczorek, 2009). The choice of markers is important and depends on the specific research aims. In this context, dominant ISSR markers (Inter Simple Sequence Repeats) use the PCR-method to amplify DNA sequences between two closed but inverted SSR (Simple Sequence Repeats) by means of a single primer, generally composed of 18-20 base pairs from a microsatellite sequence (Zietkiewicz et al., 1994). The great advantage of ISSR is that the primers work universally for most animal and plant species, so prior knowledge of genome sequences is not required. This method finds abundant polymorphisms in many systems and provides genomic information for a wide range of applications (Maltagliati et al., 2006; Wink, 2006). Furthermore, ISSR is straightforward, demands fewer experimental steps, and incurred costs are relatively low (Huang & Sun, 2000; Le Roux & Wieczorek, 2009). Only one recent study (Butterfield et al., 2015), about phylogeographic structure of red lionfish over a wide-range geographical scale, include samples from Cuba (Guantanamo Bay). Otherwise, any other geneticrelated information on the lionfish invasion in other parts of Cuba is available (Chevalier et al., 2013). The first, albeit non-confirmed, observation of lionfish in Cuba was in 2005 (Schofield et al., 2009), and the first official report of its presence was in 2007 (Chevalier et al., 2008) at six sites along the Atlantic coast (northern Cuba) and two localities on the Caribbean coast (Santiago de Cuba, southeastern Cuba). These authors identified both collected specimens as P. volitans based on morphological characters following Schultz (1986). However, both species of Pterois present in Florida, P. volitans and P. miles, are not 100% distinguishable based solely on morphology (Schofield, 2009; Jud et al., 2015). Consequently, the identification of Pterois species in different parts of Cuba requires validation using molecular tools. Recent study (Butterfield et al., 2015) confirms that this species occupy the eastern part of the island, but for other regions, such as the northern coast, no genetic information is available. This region of Cuba is particularly important, because the model of biological connectivity, proposed by Cowen et al. (2006), suggests that ocean currents could exchange individuals of P. miles between Bahamas and northern Cuba; so the distribution of P. miles could be extended to this part of the archipelago. In this study, we propose to (1) determine the ISSR markers that may be useful for molecular genetic studies of lionfish and (2) use the ISSR technique to confirm the identification of the lionfish species in Guanahacabibes National Park, Cuba. Cuban lionfishes were collected at Guanahacabibes National Park, the westernmost point of Cuba, within the Biosphere Reserve "Peninsula de Guanahacabibes". Sampling was conducted over a wide area from Cabo Corrientes to La Bajada (Fig. 1), performed by scuba divers, between 9:00-14:00 h at a water depth of 10 to 20 m. Nineteen fishes were captured using a spear, conserved in ice and transported to the laboratory. Muscle tissue was cut from each individual, placed in 96° ethanol, and finally conserved at 4°C for molecular analysis at ECOSUR (El Colegio de la Frontera Sur, Chetumal, Mexico). Reference specimens were obtained ISSR markers for Pterois species 1013 Figure 1. Location of the lionfish samples in the Caribbean Sea. Black dots indicate sampling locations. a) Localities in Cuba: 1: La Bajada and 2: Cabo Corrientes, b-c) locality in Mexico: 3: Banco Chinchorro. at the “Coral Negro” locality within the Banco Chinchorro Biosphere Reserve in the Mexican Caribbean (Fig. 1). Twenty individuals were captured and preserved in similar conditions to the Cuban specimens. Using the barcoding method, the lionfish from the Mexican Caribbean were formally identified as P. volitans (Valdéz-Moreno et al., 2012). Genomic DNA was extracted from a small part of the lionfish muscle tissue using the Wizard Genomic DNA Purification Kit (Promega) following the manufacturer’s instructions, stored at -20°C until amplification. DNA-concentration was determined by the Qubit®2.0 fluorometer (Invitrogen). Quality was checked using agarose gel (1% with TAE buffer 1X; Promega) and the post-gel staining method using GelRed™ (Quimica Valaner). To identify the more reliable ISSR markers for lionfish, we probed 23 sequences (Table 1). All primers were tested using five individuals from each locality and the optimal PCR conditions were determined for each primer. PCR amplifications were performed under the following conditions: 15 µL reaction volume containing: ~20 ng de template DNA, 1.5 µL of 5X Green Buffer (Promega), 200 µM of each dNTP from dNTP mix (Promega), 3 mM MgCl2 (Promega), 1 µM of primer (Integrated DNA Technologies), 1.25 U of GoTaq Flexi DNA Polymerase (Promega) and finally the volume was adjusted by adding ultrapure water. All amplifications were conducted in a T100 Thermal Cycler (Bio-Rad™). The cycling conditions were as follows: initial denaturation step at 94°C for 4 min, 39 cycles of denaturation at 94°C for 45s, annealing temperature (Ta) from 57°C to 66°C depending on the ISSR primer (Table 1), extension temperature at 72°C for 2 min, and a final extension at 72°C for 10 min. Amplification products were separated by electrophoresis (110 V for 2 h) using 3 µL of amplified product on agarose gels (2% in a 1X TAE Buffer, Promega) and a 100 bp DNA Ladder (Promega) was used as reference for fragment length. The bands were detected with the GelRed™ under UV light and digitized using an Imaging System (AlphaImager® Mini, ProteinSimple). A binary matrix was generated, scoring band presence (coded 1) or absence (coded 0) for each individual and primer. Only bands that scored consistently among populations were used, and we assumed that each marker band represented a distinct locus. The following informative parameters were determined at the population level: total number of bands, number of diagnostic bands and number of polymorphic bands. The binary matrix was applied to determine the percentage of polymorphism (P) and the Nei’s gene diversity (h), using corrected allele frequency (Lynch & Milligan, 1994), at the species and localities level. All analyses were carried out using GenAlex 6.501 (Peakall & Smouse, 2006) and Popgen 1.32 (Yeh & Boyle, 1999). 1014 Latin American Journal of Aquatic Research Table 1. ISSR primers screened for ISSR-PCR in lionfish. %GC (proportion of G and C bases in the sequence), Tm (melting temperature), Ta (annealing temperature), B = T, C or G; D = A, G or T; R = A or G; Y = C or T and W = A or T. Number of total bands is of 5 individuals from each locality. Primers written in bold were used for the analysis. Abbreviation (CA)7 (CT)8C (GAA)6 (CA)8GT (AC)8C (GA)8G (AC)8G (GT)8C (GA)8C (CA)8AC (GACA)4 (AG)8Y (AG)8C (GTG)5GC (CA)8AG WB(GACA)4 BDB(ACA)5 (AG)8YC (GAG)5GC (AG)8G (ACA)5BDB (GACA)4WB (CA)8RY % GC 50 52.9 33.3 50 52.9 52.9 52.9 52.9 52.9 50 50 50 52.9 70.6 50 48.1 37 52.8 70.6 52.9 37 48.1 50 Tm 55.2 55.7 53.9 62.5 62.3 55.7 62.5 60.4 56 61.4 57.1 57.6 58.2 67.8 61.1 61.5 58.4 59.5 64.8 57.5 58.6 59 62.1 Ta 54 54 52 61 61 54 61 59 54 60 56 56 57 66 60 60 57 58 63 56 57 57 61 Amplification pattern Poor amplification Poor amplification Smeared with bands Smeared with bands Smeared with bands Good Good Good Good Good Good Good Good Good Good Good Good Good Good Good Good Good Smeared In order to describe the genetic structure and variability between localities, a non-parametric analysis of molecular variance (AMOVA) (Excoffier et al., 1992, 9999 permutations) and Nei’s genetic distance analysis were performed using GenAlex 6.501 (Peakall & Smouse, 2006). In addition, a mean distance analysis using a heuristic search for an optimal tree, performed by TBR (tree–bisection-reconnection) branch swapping, was conducted using Paup 4.0b10 (Swofford, 2001). The tree was displayed using TreeView 1.5 software (Page, 1996). The distance measurement (minimum evolution) was calculated using the mean character difference. Negative branch lengths were allowed, but set to zero for tree-score calculation. Steepest descent options were not in effect. Starting tree(s) were obtained via neighbor-joining and bootstrap values were calculated under the same criteria. To confirm the reliability of the ISSR technique for identifying species, we sent samples of five individuals from Cuba for “DNA barcoding” analysis. Samples were placed in a lysis 96-well plate with a drop of 96% ethanol. Genomic DNA was extracted from tissue and the extraction process was conducted following Ivanova et al. (2006). DNA amplification and sequen- Total bands 4 5 6 4 5 5 7 8 8 8 8 9 9 10 11 11 12 13 13 14 - Size range (pb) 900-300 1100-300 800-600 800-450 1100-400 1500-900 900-200 1500-200 1500-200 1200-200 1200-200 1500-400 1600-200 1500-200 1700-100 1600-200 1400-400 1600-200 1700-200 1500-200 - cing followed the protocols of Ivanova et al. (2007). Sequences and all collateral data from specimens are available on the BOLD website (www.boldsystems.org) in the project entitled “PVCU”. We obtained functional DNA in 14 samples from Cuba and 20 from Banco Chinchorro. Out of the 23 primers tested on five individuals from each population, 17 produced clear reproducible fragments (Table 1). For this study, we selected five primers (Fig. 2) which presented a high percentage of G/C bases and a high number of bands. Finally, we obtained 113 bands of ISSR fragments (GACA) 4WB: 18 bands; (CA)8AC: 17 bands; (CA)8AG: 23 bands; (AG)8YC: 24 band and (GAG)5GC: 31 bands) using 34 individuals from both localities. Table 2 shows the numbers of bands scored, the polymorphic bands present at each locality and the number of diagnostic bands found in only one population (Luque et al., 2002). Polymorphism is high (83.5%), with the Cuban samples presenting the lowest value, Global Nei's gene diversity is 0.26 ± 0.017) with Mexican samples presenting the lowest value. AMOVA revealed that the majority of variability occurred among individuals within populations (98%, P = 0.08) and this was supported by Nei’s genetic distance value which presented very low values between ISSR markers for Pterois species 1015 Figure 2. Example of polymorphic banding patterns of the five selected markers [(AG) 8YC, (CA)8AC, (CA)8AG, (GAG)5GC, (GACA)4WB] for both localities. The first line corresponds to the DNA ladder (from 100 bp to 1000 bp by steps of 100 bp and one band at 1500 bp), Cu: individuals from Cuba, BC: individuals from Mexico. both localities (0.035) (Fig. 2). Distance analysis did not demonstrate any significant differences or grouping between our two populations. No clusters were discernible and there were no bootstrap values above 50% (Fig. 3). Using the tools provided by bold-ids, the obtained DNA barcode confirmed the identification of P. volitans in the Guanahacabibes National Park, Cuba, regrouped into the cluster with P. volitans individuals from Quintana Roo, previously identified (ValdezMoreno et al., 2012). The BLAST® tool from GenBank also confirmed the species found in the Guanahacabibes National Park, Cuba, as P. volitans. This first preliminary study identified a high number of ISSR loci for the analysis of genetic variability and population structure of the lionfish in the Caribbean. Due to the high level of ISSR resolution for the study of contemporary events, these markers are excellent candidates for genetic studies of biological invasions. In this study, the number of bands amplified by five primers were 113 (102 polymorphic) considered sufficient for species determination and studies of population genetics. Indeed, other studies of molecular identification and population genetics in fish species detected a similar number of bands. For example, Casu et al. (2009) detected 97 fragments when considering eight primers in Dentex dentex L. 1758 (Perciformes, Figure 3. Unrooted tree obtained by distance analysis of lionfish samples from localities in Cuba and Mexico. Sparidae). A study on Cynoglossus semilaevis Günther, 1873 (Pleuronectiformes, Cynoglossidae) reported 137 fragments using 19 ISSR primers (Liu et al., 2009). 1016 Latin American Journal of Aquatic Research Table 2. Lionfish genetic diversity based on ISSR markers in Cuban and Mexican localities. n: number of individuals kept for analysis; N1: number of bands scored; N2: number of polymorphic bands; N3: number of diagnostic bands; P: percentage of polymorphism; h: Nei’s gene diversity; SD: standard deviation. Locality Mexico Cuba n 14 20 N1 107 105 N2 82 79 Maltagliati et al. (2006) recorded 101 bands amplified by nine ISSR primers in cyprinodontiform fish. This study provides definite confirmation that the species presents in the Guanahacabibes National Park, Cuba is P. volitans. Diagnostic bands (Luque et al., 2002) are important for the discrimination of species, particularly fish species (Maltagliati et al., 2006; Casu et al., 2009). The identification of species using the ISSR method always reveals a high number of diagnostic bands (Maltagliati et al., 2006; Casu et al., 2009). Our study did not identify many diagnostic bands; however, we observed a high number of common bands between both localities, confirming that all the individuals belong to the same species: P. volitans. This is further confirmed by the lack of structure in the unrooted tree, the results of AMOVA and the very low genetic distances. This work is an initial analysis of genetic aspects of the lionfish invasion in Cuba using ISSR. Additionally, we suggest that this technique is an excellent alternative for low-cost genetic monitoring focused on improving control programs of this invasive species in regions with insufficient financial resources. Given that Guanahacabibes was one of the last places in Cuba to be colonized by lionfish (late 2009) (Chevalier et al., 2013), we recommend extending this research to the rest of the Cuban Archipelago. Considering that the first sightings of P. volitans were reported on the north coast of Cuba, the genetic analysis of populations both in the north of the archipelago and along the entire Cuban coast is advocated, with the aim of obtaining a complete genetic characterization of this invasive fish in Cuba. ACKNOWLEDGEMENTS We are grateful to the “Consejo Nacional de Ciencia y Tecnología” (CONACyT) for the financial support provided through the scholarship No. 288387. Thanks to the Comisión Nacional de Áreas Naturales Protegidas” (CONANP) and the “Comisión Nacional de Acuacultura y Pesca” (CONAPESCA) for granting permission for the collection of specimens in Mexico. We are indebted N3 4 2 P (%) 75.2 72.5 h (± SD) 0.246 (0.018) 0.253 (0.019) to the fishermen of “Banco Chinchorro” for their help during the capture of specimens and appreciate the permission for the collection and exportation of specimen provided by the “Instituto de Medicina Veterinaria de Cuba”. 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Genome fingerprinting by simple sequence repeat (SSR)anchored polymerase chain reaction amplification. Genomics, 20(2): 176-183. ISSR markers for Pterois species 1019 Lat. Am. J. Aquat. Res., 43(5): 1019-1023, 2015 rápido para el conteo de leucocitos en trucha arcoíris Método DOI: 10.3856/vol43-issue5-fulltext-22 1019 Short Communication Método rápido para la cuantificación de leucocitos sanguíneos y su utilidad en la evaluación del estado de salud en trucha arcoíris Oncorhynchus mykiss Libertad Alzamora-Gonzales1, Carolina de Amat-Herbozo1, Erasmo Colona-Vallejos1 Elizabeth Cervantes-Aguilar2, Richard Dyer Velarde-Álvarez2 Ronald Aquino-Ortega1 & Miguel Ángel Aguilar-Luis1 1 Laboratorio de Inmunología, Instituto de Investigación de Ciencias Biológicas Antonio Raimondi, Universidad Nacional Mayor de San Marcos Av. Universitaria s/n, Ciudad Universitaria de San Marcos, Lima, Perú 2 Cytometric Bioservices S.A.C., Av. José Gálvez Barrenechea Nº387, San Isidro, Lima, Perú Corresponding autor: Libertad Alzamora Gonzales ([email protected]) RESUMEN. El análisis de la proporción y cantidad de células sanguíneas es una forma muy confiable de evaluar el estado de salud en humanos y otras especies. El objetivo fue estandarizar una metodología para la cuantificación rápida de poblaciones de leucocitos sanguíneos de Oncorhynchus mykiss (trucha arcoíris). Se procesaron muestras de leucocitos obtenidos de la sangre de un grupo de truchas juveniles saludables mantenidas en el laboratorio. Las muestras fueron analizadas empleando el minicitómetro Scepter™ y los resultados fueron contrastados con los obtenidos por citometría de flujo. Los histogramas generados por ambos métodos mostraron un máximo correspondiente a la población de linfocitos/trombocitos y otro a la de monocitos/neutrófilos. No se encontraron diferencias significativas entre los resultados de ambos métodos (P > 0,05). El método con el minicitómetro se utilizó para evaluar muestras de truchas procedentes de una piscigranja, el perfil obtenido mostró la disminución significativa de neutrófilos compatible con los signos clínicos de enfermedad observados en los especímenes evaluados. Estos resultados indican que la metodología aplicada es válida y útil para determinar las concentraciones y proporciones celulares en muestras de sangre en trucha arcoíris y permiten el análisis rápido de su estado de salud. Palabras clave: Oncorhynchus mykiss, trucha arcoíris, hemogramas en peces, leucocitos sanguíneos, acuicultura. Rapid method for counting of blood leukocytes and its usefulness in health status assessment of rainbow trout (Oncorhynchus mykiss) ABSTRACT. The analysis of the ratio and number of blood cells is a very reliable way to assess the health status in humans and other species. The aim was to standardize a methodology for rapid quantification of blood leukocytes in rainbow trout Oncorhynchus mykiss. Samples of blood leukocytes obtained from a group of healthy juvenile trout maintained in the laboratory were processed. The samples were analyzed using a Scepter™ minicytometer, the results were compared with those obtained by flow cytometry. Histograms generated by both methods showed a peak corresponding to the population of lymphocytes/thrombocytes and one of monocyte/neutrophil. Non-significant differences were found between the results of both methods (P > 0.05). The method employing minicytometer was used to evaluate samples of trout from a fish farm, the profile obtained showed a significant decrease in the neutrophils consistent with clinical signs of disease observed in the tested specimens. These results indicate that the methodology is valid and useful in determining the concentrations and cell proportions in blood samples of rainbow trout and allow rapid analysis of its health status. Keywords: Oncorhynchus mykiss, rainbow trout, blood counts in fish, blood leukocytes, aquaculture. __________________ Corresponding editor: Herman Dantagnan 1020 Latin American Journal of Aquatic Research La trucha arcoíris Oncorhynchus mykiss es una especie con alto grado de adaptabilidad a condiciones artificiales de cría, lo cual ha favorecido la intensificación de su producción en varios países del mundo, especialmente en los últimos años. Las condiciones en que los peces se crían los exponen a problemas de contaminación del agua y crean una serie de limitaciones fisiológicas que provocan estrés y brotes epizoóticos, causados por diversos microorganismos patógenos perjudicando así la economía de las empresas productoras. La oportuna evaluación y monitoreo del estado de salud de los animales es importante porque ayuda a prevenir y controlar oportunamente estos problemas (Bueñaño, 2010), facilitado por el desarrollo de una serie de herramientas biotecnológicas. Las alteraciones en los parámetros hematológicos constituyen un buen indicativo del estado de salud en vertebrados (Blaxhall, 1972; Amend & Smith, 1975; Clauss et al., 2008; Bueñaño, 2010). El grado y tipo de alteración varía según la especie y agente causal. Así, en algunas especies incluyendo la trucha arcoíris, se ha observado que la proporción de leucocitos, linfocitos, monocitos, trombocitos y/o neutrófilos aumenta o disminuye según se trate de un proceso infeccioso o una exposición a productos químicos contaminantes (Amend & Smith, 1975; Sjöbeck et al., 1984; Gill & Pant, 1985; Oluah & Mgbenka, 2004; Velisek et al., 2009; Zorriehzahra et al., 2010; Li et al., 2011). Para este tipo de estudios se puede optar por realizar un hemograma convencional. Sin embargo, este método puede tomar mucho tiempo, sin mencionar la dificultad en diferenciar los diferentes tipos celulares presentes en trucha arcoíris. Además, la citometría de flujo ha resultado ser una técnica rápida y muy confiable para cuantificar y caracterizar algunas poblaciones celulares y estudiar procesos inmunopatológicos en peces (Morgan et al., 1993; Chilmonczyk & Monge, 1999). Para trucha arcoíris, la citometría de flujo permite diferenciar básicamente la población de eritrocitos, linfocitos/trombocitos y granulocitos, facilitando el monitoreo de la dinámica de la población celular de manera rápida y confiable (Morgan et al., 1993). No obstante, esta técnica por su de elevado costo, es poco accesible. El objetivo del presente trabajo fue estandarizar una metodología para cuantificar poblaciones de leucocitos en sangre de juveniles de trucha arcoíris utilizando el contador celular Scepter™ 2.0 (Merck Millipore), comparando los datos con los obtenidos por citometría de flujo (Gold standard). Además, se evaluó su potencial para diferenciar el estado inmunológico de especímenes sanos y con signos clínicos de enfermedad (oscurecimiento del cuerpo, exoftalmia, etc.). Para la estandarización del método, se evaluó un grupo de truchas juveniles saludables (n = 12), procedentes de Canta (Lima, Perú), que fueron mantenidas durante 2 meses en acuarios del Laboratorio de Inmunología de la Facultad de Ciencias Biológicas (Universidad Nacional Mayor de San Marcos, Lima, Perú), para verificar su estado y descartar una posible infección. Los especímenes se anestesiaron empleando MS-222 (Sigma), las muestras de sangre se extrajeron por punción cardiaca o de la vena caudal en tubos con EDTA y se mantuvieron en frío hasta su procesamiento dentro de las 24 h siguientes. Los eritrocitos de las muestras fueron eliminados por lisis hipotónica siguiendo el método de Crippen et al. (2001) con ligeras modificaciones. Se tomaron 200 µL de la sangre obtenida y se agregaron 200 µL de una mezcla de solución Alsever con solución de Hank (1:1). Se adicionaron 3,6 mL de agua destilada a 4°C y se incubó por 30 s invirtiendo el tubo dos veces para mezclar. Para detener la lisis se agregó 400 µL de PBS 10X. Se centrifugó a 700 g por 10 min, se retiró cuidadosamente el sobrenadante, el pellet de leucocitos se resuspendió en 800 µL de solución Alsever- Hank (1:1) y se analizaron por citometría de flujo (n = 6) y con el minicitómetro Scepter™ 2.0 (n = 6). Para las pruebas de citometría se empleó el citómetro de flujo BD FACS Calibur y las células se identificaron con anticuerpos policlonales contra leucocitos de trucha arcoíris obtenidos en ratón. Los anticuerpos se marcaron con Fab-anti Fc de ratón (IgG1) unido a aloficocianina (Zenon ® de Invitrogen), se adquirió un total de 20.000 eventos por cada muestra y los datos obtenidos se analizaron con el programa WinList 3D 8.0. Para la cuantificación de leucocitos empleando el Scepter™ 2.0 se siguieron las instrucciones del fabricante, la suspensión de leucocitos se diluyó 1:10 (5x105 células mL-1 aproximadamente) y se leyó con un sensor de 40 µm. Los histogramas generados fueron analizados con Scepter Software Pro. Para verificar la utilidad del método rápido descrito, empleando Scepter™ 2.0, se procesaron muestras de sangre de 12 truchas con signos clínicos de enfermedad (exoftalmia, oscurecimiento del cuerpo o hinchazón abdominal), procedentes de la Piscigranja Municipal de Callahuanca, Provincia de Huarochirí-Departamento de Lima, Perú (11°49’35.39”S, 76°37’7.1”W). El peso promedio de las truchas evaluadas criadas en laboratorio fue de 35 g y la talla media de 16 cm, estos son juveniles de edad promedio de 4 meses. En el caso de las truchas procedentes de la Piscigranja, el peso medio fue de 46 g y la talla media de 20 cm, que se extrajeron de las pozas de juveniles. Sin embargo, es probable que el peso y talla de estos especímenes estén Método rápido para el conteo de leucocitos en trucha arcoíris influenciados por el mal estado de salud que mostraban al momento de la evaluación. Mediante la prueba t-Student se compararon los valores porcentuales obtenidos por el método ScepterTM 2.0 y citometría de flujo; y las concentraciones celulares que resultaron con ScepterTM 2.0 para las muestras procedentes de las truchas saludables (n = 12) y con signos de enfermedad (n = 12). Los gráficos de puntos Forward scatter vs Side scatter obtenidos por citometría de flujo indican tres poblaciones (Fig. 1a). La población más densa (71.974.0%) fue aquella de menor tamaño y granularidad (R1), que correspondería principalmente a la población de linfocitos y en muy baja proporción a la de trombocitos. Las otras dos poblaciones son menos densas (6,7-10,5 y 17.9-19.9%), de mayor tamaño y complejidad, correspondiente a poblaciones de monocitos y polimorfonucleares (R2 y R3 respectivamente). Los histogramas de las muestras presentan dos máximos (Fig. 1b), de los cuales el primero y más alto 1021 corresponde a la población R1 y el segundo a una superposición de las otras dos poblaciones (R2 y R3). Los histogramas de muestras de truchas saludables obtenidos por ScepterTM presentaron un patrón similar a los de citometría de flujo (Fig. 1c). Los marcadores de los dos máximos se describen en el Scepter software Pro como O1 (primer máximo) y O2 (segundo máximo). No se encontraron diferencias significativas al comparar los porcentajes de los marcadores O1 con el correspondiente al primer máximo de citometría de flujo (P = 0,48) ni de los marcadores O2 con el segundo máximo (P = 0,39) (Tabla 1). Sin embargo, los valores obtenidos con ScepterTM presentan mayor desviación estándar. El método ScepterTM tiene la ventaja de proporcionar datos de porcentaje y concentración de células en una muestra considerando el factor de dilución. En el análisis realizado se obtuvo un promedio general de 23,82 ± 4,39x106 cél mL-1, que coincide con los resultados de otros autores para trucha arcoíris Figura 1. Muestras de leucocitos de sangre de trucha arcoíris. a) Gráfica de puntos obtenida por citometría de flujo donde se definen las poblaciones R1 de linfocitos/trombocitos (verde), R2 de monocitos (anaranjado) y R3 de polimorfonucleares (azul), b) histogramas de ejemplares saludables generados por citometría de flujo. Se observa un primer máximo que representa a R1 unido a un segundo máximo correspondiente a una superposición de R2 con R3, c) histogramas de truchas saludables generados por Scepter, que presentan el mismo perfil del histograma generado por citometría de flujo, se muestran las regiones O1 y O2 delimitadas, d) histogramas de truchas con signos clínicos de enfermedad generados por ScepterTM, los cuales presentan menor cantidad de células en la región O2, con respecto a los histogramas de truchas saludables. 1022 Latin American Journal of Aquatic Research Tabla 1. Comparación de porcentajes de leucocitos de sangre de truchas saludables utilizando Scepter TM y citometría de flujo. PROM: promedio; DE: desviación estándar; Región O1: primer máximo del histograma para Scepter TM y citometría de flujo; Región O2: segundo máximo del histograma para Scepter TM y citometría de flujo; N° de muestras evaluadas: 12. Las evaluaciones por ambos métodos (Scepter y citometría de flujo) se realizaron por duplicado. Método ScepterTM Citometría de flujo Región O1 % PROM DE 73,9 11,14 78,9 6,00 Región O2 % PROM DE 27,3 11,54 20,9 5,85 Tabla 2. Comparación de las concentraciones de leucocitos de sangre de trucha arcoíris saludable y de truchas con signos clínicos de enfermedad, utilizando Scepter TM. Región O1: Primer máximo del histograma para Scepter TM y citometría de flujo. Región O2: Segundo máximo del histograma para Scepter TM y citometría de flujo. (*) P < 0,05. Leucocitos Truchas saludables (n = 12) Truchas con signos de enfermedad (n = 12) (Yasutake & Wales, 1983; Crippen et al., 2001; Bueñaño, 2010). Por otro lado, empleando ScepterTM se observaron diferencias significativas (P < 0,05) entre las muestras de sangre de truchas saludables adaptadas al laboratorio y truchas con signos de enfermedad procedentes de la piscigranja. En estas últimas muestras se observó mayor porcentaje en el máximo correspondiente a linfocitos, que alcanzó un promedio de 98,83 ± 0,39%; mientras que en la región de los otros leucocitos, el porcentaje bajó a un promedio de 1,37 ± 0,47%. El empleo del ScepterTM permitió calcular la concentración celular en las muestras de sangre de trucha y se pudo evaluar el aumento o disminución de células de cada región, independientemente de su proporción. De esta manera, se pudo determinar que el máximo correspondiente a linfocitos fue relativamente superior (O1), sin mostrar diferencias significativas respecto a las muestras de truchas mantenidas en laboratorio; mientras que la diferencia entre el número de células de la región O2 (segundo máximo) fue significativamente inferior en las truchas con signos de enfermedad, con disminución en la cantidad de monocitos y neutrófilos (neutropenia) (Fig. 1d) (Tabla 2). El método de recuento de células sanguíneas de trucha arcoíris empleando el minicitómetro Scepter TM 2.0 (Merck Millipore) permite determinar las concentraciones y proporciones celulares en muestras de sangre, apostando de una imagen rápida del estado de salud de los especímenes evaluados. Sin embargo, para el análisis de mayor precisión es recomendable realizar evaluaciones mediante citometría de flujo Región O1 N° células x 106 mL-1 Región O2 N° células x 106 mL-1 17,63 ± 3,79 19,98 ± 3,06 6,19 ± 3,42 0,25 ± 0,11* utilizando anticuerpos monoclonales, ya que lo anticuerpos policlonales no permitieron discriminar adecuadamente las poblaciones celulares, por esta razón los resultados se basan en los parámetros de citometría de flujo: Fordware scatter vs Side scatter. Estos resultados muestran que el método utilizado para la cuantificación de linfocitos y otros leucocitos empleando ScepterTM es válido y útil para el análisis rápido del estado de salud de trucha arcoíris. El método también tiene la cualidad que no es necesario sacrificar a los especímenes, pues no se utiliza el bazo o el riñón anterior para determinar la cantidad de las células que participan en la inmunidad. En cuanto a rapidez tiene ventaja sobre la cuantificación por hemograma convencional, la cual es muy laboriosa y requiere mayor experiencia, emplea mayor tiempo aunque proporciona mayores detalles. Finalmente, los resultados indican que el método Scepter TM es comparable a la citometría de flujo con la ventaja de ser más económico. AGRADECIMIENTOS Los autores agradecen al Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica (Proyecto FONDECYT 393-2012-CONCYTEC-OAC) por el financiamiento otorgado para la realización del estudio. REFERENCIAS Amend, D.F. & L. Smith. 1975. 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Anim. Health, 13: 234245. Gill, T.S. & J.C. Pant. 1985. Mercury-induced blood anomalies in the freshwater teleost Barbus conchonius Ham. Water Air Soil Pollut., 24(2): 165-171. Li, Z.H., V. Zlabek, J. Velisek, R. Grabic, J. Machova, J. Kolarova, P. Li & T. Randak. 2011. Acute toxicity of carbamazepine to juvenile rainbow trout (Oncorhynchus mykiss): effects on antioxidant responses, hematological parameters and hepatic EROD. Ecotox. Environ. Safe., 74: 319-327. Received: 22 August 2014; Accepted: 26 September 2015 1023 Morgan, J.A.W., T.G. Pottinger & P. Rippon. 1993. Evaluation of flow cytometry as a method for quantification of circulating blood cell populations in salmonid fish. J. Fish Biol., 42(1): 131-141. Oluah, N.S. & B.O. Mgbenka. 2004. Effect of actellic 25 EC on the differential leucocyte counts of the catfish Clarias albopunctatus (Nichole & Lamonte, 1953). Anim. Res. Int., 1(1): 52-56. Sjöbeck, M.L., C. Haux, Å. Larsson & G. Lithner. 1984. Biochemical and hematological studies on perch, Perca fluviatilis, from the cadmium-contaminated river Emån. Ecotox. Environ. Safe., 8(3): 303-312. Velisek, J., Z. Svobodova & V. Piackova. 2009. Effects of acute exposure to bifenthrin on some haematological, biochemical and histopathological parameters of rainbow trout (Oncorhynchus mykiss). Vet. MedCzech., 54(3): 131-137. Yasutake, W. & J. Wales. 1983. Microscopic anatomy of salmonids: an atlas. Fish and Wildlife Service, Washington D.C., 207 pp. Zorriehzahra, M.J., M.D. Hassan, M. Gholizadeh & A.A. Saidi. 2010. Study of some hematological and biochemical parameters of rainbow trout (Oncorhynchus mykiss) fry in western part of Mazandaran province, Iran. J. Fish. Sci., 9(1) 185-198. Lat. Am. J. Aquat. Res., 43(5): 1024-1029, Epibiont data in2015 relation with the Debilitated Turtle Syndrome in sea turtles from Chile coast DOI: 10.3856/vol43-issue5-fulltext-23 1024 1 Short Communication Analysis of epibiont data in relation with the Debilitated Turtle Syndrome of sea turtles in Chelonia mydas and Lepidochelys olivacea from Concepción coast, Chile Italo Fernández1, Marco Antonio Retamal2, Miguel Mansilla3, Francisco Yáñez1, Víctor Campos1 Carlos Smith1, Guillermo Puentes6, Ariel Valenzuela4 & Hernán González5 1 Departamento de Microbiología, Facultad de Ciencias Biológicas Universidad de Concepción, Concepción, Chile 2 Departamento de Oceanografía, Facultad de Ciencias Naturales y Oceanográficas Universidad de Concepción, Concepción, Chile 3 Facultad de Medicina Veterinaria, Universidad San Sebastián, Concepción, Chile 4 Laboratorio de Piscicultura y Patología Acuática, Facultad de Ciencias Naturales y Oceanográficas Universidad de Concepción, Concepción, Chile 5 Facultad de Medicina Veterinaria, Universidad Iberoamericana de Ciencias y Tecnología, Santiago, Chile 6 Facultad de Medicina Veterinaria, Universidad Santo Tomás, Concepción, Chile Corresponding author: Italo Fernández ([email protected]) ABSTRACT. Epibionts on the surface of the skin and shell of a specimen of Chelonia mydas and three Lepidochelys olivacea found floating on the coast of Concepción, Chile, between June 2010 and December 2012, were analyzed. These epibionts were analyzed during the clinical inspection and the tissue changes related to its settlement, with filamentous algae around, were observed. Subsequently, the epibionts were identified by morphological observation. The knowledge about theses epibionts in Chile is reviewed and the potential occurrence of Debilitated Turtle Syndrome (DTS) in these turtles is discussed. The presence of sea turtles in the Chilean coast is considered a casual event, so there is little information on this issue. We propose it is necessary to carry out more studies on the association between turtles and epibionts because their identification, colonizing reptiles’ surface may give relevant information to a better understanding of different diseases, including DTS, that affect these marine reptiles and facilitates the development of strategies intended to recover their populations. Keywords: Lepidochelys olivacea, Chelonia mydas, sea turtles, epibionts, Concepción coast, Chile. Análisis de los datos de epibiontes en relación con el Síndrome de Debilitamiento de Tortugas marinas en Lepidochelys olivacea y Chelonia mydas de la costa de Concepción, Chile RESUMEN. Se presenta el hallazgo de epibiontes en la superficie de la piel y caparazón de un ejemplar de Chelonia mydas y tres de Lepidochelys olivacea encontrados flotando frente a la costa de Concepción, Chile, entre junio de 2010 y diciembre de 2012. Los epibiontes se visualizaron clínicamente y se observaron alteraciones tisulares relativas a su asentamiento junto con algas filamentosas a su alrededor. Los epibiontes se identificaron por observación morfológica. Se presenta una revisión respecto del conocimiento en Chile de los organismos encontrados y se discute la potencial ocurrencia del Síndrome de Debilitamiento de Tortugas (SDT) en los caparazones analizados. La presencia de tortugas marinas en el litoral chileno es un evento ocasional y existe escasa información respecto de esta problemática. Se recomienda realizar estudios sobre la asociación entre las tortugas y epibiontes porque su identificación, colonizando la superficie de estos reptiles, puede aportar datos relevantes para una mejor comprensión de las enfermedades que afectan a las tortugas marinas, incluyendo el SDT, y facilita el desarrollo de estrategias destinadas a recuperar sus poblaciones. Palabras clave: Lepidochelys olivacea, Chelonia mydas, tortugas marinas, epibiontes, costa de Concepción, Chile. __________________ Corresponding editor: Sergio Palma 1025 2 Latin American Journal of Aquatic Research Among the seven sea turtles species existing worldwide, four of them have been recorded in Chilean waters: Green turtles (Chelonia mydas Linnaeus, 1758), Loggerhead turtles (Caretta caretta, Linnaeus 1758), Leatherback turtles (Dermochelys coriacea Vandelli, 1761) and Olive Ridley turtles (Lepidochelys olivacea Eschcholtz, 1829). Although few turtles are documented in northern Chile, their movements into Chilean waters is considered passive and likely attributable to oceanic currents, meteorological events and atmospheric changes due to El Niño Oscillation events (Ibarra-Vidal & Ortiz, 1990). On the other hand, in certain seasons, when the littoral waters of central to southern Chile are suitable, their pelagic habits may allow them to migrate and temporarily occupy habitats beyond their typical southernmost range in northern Chile reaching the waters of the present study area (Azócar et al., 2011). Sea turtles are an appropriate substrate for the attachment of a great variety of algae and invertebrate larvae present in the water column. This attachment results in associations of the commensal, opportunistic and mutualism type with organisms such as cirripeds, algae, bryozoans, cnidarians, polychaetes and amphipods among others (Frick & Pfaller, 2013). Because these associations occur only when the distribution of these species and their hosts overlap, these organisms can be important biological markers of the movement patterns and geographical distribution of sea turtles, as well as indicators of host turtle activity and migration routes (Eckert & Eckert, 1988). From June 2010 to December 2012, one specimen of Chelonia mydas and three of Lepidochelys olivacea were found at four different localities along the centralsouth coast of Chile, particularly in the littoral habitats of the Concepción coast (36°46’22’’S-37°23’52’’S). The four turtles were collected by the National Fishery Service of Chile and they were sent to the Veterinary Hospital of San Sebastian University, Concepcion, Chile. Species were identified on the basis of morphological characteristics, as defined by Márquez (1990), and sex, maturity status, length and weight for each animal were also recorded (Table 1). The health condition of each animal was determined through clinical examinations all of which showed that the four turtles in question were clinically unhealthy (inattentive to surrounding stimuli, general weakness, plastron weakness and lesions of diverse degrees, notably ocular ulcerations and scars in the skin and carapace). Haematology and clinical biochemistry tests were perfomed and obtained values from the four turtles showed alterations when compared with normal reference values (Anderson et al., 2011; Santoro & Meneses, 2014). Consequently, condition of the four animals determined their hospitalization and emergency clinical procedures were applied. After a careful external examination (carapace, plastron, flippers, skin, head and neck, cloaca and tail) epibiotic organisms and algae were removed using tweezers and a spatula, fixed in 10% buffered formalin and finally placed in 70% ethyl alcohol for further analysis. Epibionts and algae were sent to the Laboratory of Parasitology, Faculty of Biological Sciences, University of Concepcion, Concepción. Chile where, using light microscopy and bibliographic references (Hoffmann & Santelices, 1997; Young, 1999), specimens were identified to the lowest possible taxon. The taxonomic identification of epibionts and algae found on the four turtles is detailed in Figure 1 and Table 1. In the case of epibionts found on C. mydas, they were two specimens of Chelonibia testudinaria located on the second central scute and second lateral scute, as two masses firmly adhered to the surface and with abundant filamentous algae of the genus Ulva (Case study 1). One L. olivacea turtle, whose clinical condition was considered as the most serious, displayed the highest density of epibiont aggregations and died shortly after collection (Case study 3). On post-mortem exami-nations, this turtle had emaciation and abundance signs of secondary infections. The remaining three turtles recovered satisfactorily and where set free along the coast of northern Chile. The epibionts of L. olivacea were typically represented by masses of filamentous algae and sand. Goose barnacles Lepas anatifera were observed from all three L. olivacea at various locations on the skin, including both front flippers on one animal (Case study 2), on the left front flipper of the second (Case study 3) and on the right back flipper of the third turtle (Case study 4). Additionally, two L. olivacea hosted numerous hydrozoans growing in association with the macroalgae Ulva on several carapace scutes where sandy areas had accrued (Case study 2 and 3). The most intensively colonized animal also showed the presence of algae of genera Polysiphonia and Rhodymenia (Case study 3). In Chilean waters, the presence of epibionts in C. mydas is recorded in only five specimens at the northern coast, revealing the presence, on the shells, of gastropod mollusks and crustacean belonging to the families Talitridae, Aoridae and Gammaridae (López et al., 2007). Although C. testudinaria has already been reported in Chilean waters (Bettini & Ross, 2002), this is the first report of this organism attached to a C. mydas in Chile. C. testudinaria, an obligate commensal of motile marine animals with a cosmopolitan distribution, is frequently found on the shell and plastron of turtles but they also can be found on the head, flippers and skin (Frick & Ross, 2001). Three species of cirri- Epibiont data in relation with the Debilitated Turtle Syndrome in sea turtles from Chile coast 1026 3 Table 1. Sea turtle species, location rescue, reproductive and biometrical characteristics, epibionts and algae found of four sea turtles from south-central Chile (2010-2012). Case report sea turtle species Date/Location Reproductive and biometrical characteristics Adult, male Weight: 48 Kg Lenght: Head: 34 cm; tail: 27 cm Carapace: lenght:78 cm width: 74 cm Epibionts and algae (number of specimens/locations) - Chelonibia testudinaria (2/carapace) - Ulva sp. (carapace) Case 2 Lepidochelys olivacea 08/12/2011 Penco Beach (36°43’0”S, 72°58’00”W) Adult, male Weight: 32 Kg Lenght: Head: 25 cm; tail: 24 cm Carapace: lenght:68 cm width: 70 cm - Hydrozoa (55/carapace) - Lepas anatifera (10/anterior flippers) - Ulva sp. (carapace) Case 3 Lepidochelys olivacea 05/30/2012 Tubul Beach (37°13’44”S, 73°26’36”W) Adult, female Weight: 45 Kg Lenght: Head: 25 cm; tail: 20 cm Carapace: lenght: 67 cm width: 71 cm - Hydrozoa (17/carapace) - Lepas anatifera (3/left anterior flipper) -Ulva sp., Polysiphonia sp.,Rhodymenia sp. (carapace) Case 4 Lepidochelys olivacea 12/11/2012 Talcahuano Beach (36°43’0”S; 73°07’00”W) Adult, female Weight: 35 Kg Lenght: Head: 22 cm; tail: 18 cm Carapace: lenght:67 cm width: 70 cm - Lepas anatifera (8/right back flipper) Case 1 Chelonia mydas 06/21/2010 Itata Beach (36°37’0”S, 72°57’00”W) peds and one decapod has been reported on L. olivacea turtles captured along the central to southernmost portions of Chile (Retamal & Hermosilla, 1969; Brito, 2007). Meanwhile, Lepas anatifera, is an opportunist pelagic barnacle common in all oceans, including Chilean waters (Hinojosa et al., 2006). It is frequently observed on the carapace region and skin of turtles of different species that spend a great deal of time at the water’s surface –including healthy turtles. This barnacle has been detected on the carapaces of two specimens of L. olivacea along the central-south coast of Chile (Miranda & Moreno, 2002). Their occurrence on the tips of the front and rear flippers of turtles, however, is generally indicative of limited flipper activity by host turtles, and could indicate relatively inactive turtles (M.G. Frick, pers. comm.). Although, hydrozoans specimens found on L. olivacea have not been identified, their presence associated to barnacles, such as Lepas anatifera and algae would be frequent due to their necessity to occupy the surface of these animals to settle, feed and reproduce themselves. With respect to the algae observed on the turtles examined here, their presence on the surface of the epibiotic barnacles we observed is not surprising as all are common and often lead to the recruitment of other epibiotic forms onto host turtles (Scharer, 2003). In the present case, however, the density and size of some of the algal species encountered herein suggests that a potential decrease in the activity of the host turtle is likely the responsible for the observed growth. Algae of genera Ulva, Polysiphonia and Rhodymenia are common in the Chilean coast (Hoffmann & Santelices, 1997). The observation of specimens of sea turtles into the waters of central-southern Chile is unusual and, in accordance with our experience, it is the result of an event implying some damage or health deterioration of the animal. While meteorological events may be involved, we think that the debilitated state of the turtles of this study likely represent turtles that were cold-stunned, then got sick, and then were passively carried into more southerly waters. Cold-stunning symp- 41027 Latin American Journal of Aquatic Research a b c d Figure 1. Macroscopic and microscopic features of epibionts and algae observed on sea stranded turtles at the coast south central Chile (2010-2012). a) Chelonibia testudinaria extracted from C. mydas (2010), b) Polysiphonia sp. from L. olivacea, 100x (2012), c) two specimens of Lepas anatifera (back-lateral location; left anterior flipper of C. mydas (2012), d) Turtle’s carapace (L. olivacea) densely colonized by epibionts and algae. toms, such as debilitation, lethargic movement, scarce mobility in head and flippers and feeble attempts to dive, may be present when sea turtles are exposed to rapidly cooling water temperatures or are exposes to water temperatures of less than 15°C (Milton & Lutz, 2003) as it is the case of waters of central-southern Chile (Sobarzo, 1994). Moreover, we believe that the four turtles suffering Debilitated Turtle Syndrome (DTS), based on the clinical features described above and the results of haematology and clinical biochemistry tests. Turtles exhibiting symptoms of DTS are characteristically emaciated, anemic, hypoglycaemic, and are often covered by barnacles when they strand (Sloan et al., 2014). Consistent with this, it was remarkable that at least two of the four turtles (case study 2 and 3) of this study showed low plasmatic concentration of total protein, albumin, cholesterol and glucose, which could be attributed to poor nutrition or altered carbohydrate metabolism by liver damage. In addition, the same turtles showed high levels of uric acid and urea nitrogen, elements which are considered as the best indicators of liver damage, because both are end products of protein metabolism. Therefore, these values may reflect poor nutrition, protein loss due to diarrhea or nephropathy, chronic infection, parasitism, immune deficiency related to their state of weakness, or a combination of all these causes (Deem et al., 2009). This condition (DTS) may have favoured the epibiont colonization. The state of debilitation of turtles were suffering DTS results in a sustained period of reduced activity, stationary floating and decreased grooming, which likely facilitates algae and invertebrate larvae attachment (Day et al., 2010). Current information indicates that debilitated turtles are immunosuppressed or lethargic prior to barnacle colonization and that limited mobility by the host likely facilitates rapid and prolific colonization of barnacles (Frick & Pfaller, 2013). Likewise, the type of epibiont growth and the effects associated reported here would represent secondary agents in the decline in the health of these turtles. 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