Aquatic Ecology Assessment at Boteka Aquatic Ecology
Transcription
Aquatic Ecology Assessment at Boteka Aquatic Ecology
Aquatic Ecology Assessment at Boteka Aquatic Ecology Project Number: CDC2950 Prepared for: Feronia PHC August 2015 _______________________________________________________________________________________ Digby Wells and Associates (South Africa) (Pty) Ltd (Subsidiary of Digby Wells & Associates (Pty) Ltd). Co. Reg. No. 2010/008577/07. Fern Isle, Section 10, 359 Pretoria Ave Randburg Private Bag X10046, Randburg, 2125, South Africa Tel: +27 11 789 9495, Fax: +27 11 789 9498, [email protected], www.digbywells.com _______________________________________________________________________________________ Directors: DJ Otto, GB Beringer, LF Koeslag, AJ Reynolds (Chairman) (British)*, J Leaver*, GE Trusler (C.E.O) *Non-Executive _______________________________________________________________________________________ This document has been prepared by Digby Wells Environmental. Report Type: Aquatic Ecology Project Name: Aquatic Ecology Assessment at Boteka Project Code: CDC2950 Name Responsibility Company Date Russell Tate (Pr. Sci. Nat.) Survey and report writer Digby Wells Environmental August 2015 Brett Reimers Report Reviewer Digby Wells Environmental May 2015 Marion Thomas Report Reviewer Digby Wells Environmental May 2015 This report is provided solely for the purposes set out in it and may not, in whole or in part, be used for any other purpose without Digby Wells Environmental prior written consent. Digby Wells Environmental i Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 EXECUTIVE SUMMARY Digby Wells Environmental was commissioned by Feronia PHC to conduct aquatic ecological specialist studies on their Boteka oil palm concession, located within the central Congo basin. The aim of this study was to establish the conservation value of the aquatic ecosystems associated with the oil palm concession. As such, this study aims to establish the ecological status, degree of endemism, conservation status of species and overall conservation value of the associated river courses. The river systems associated with the Boteka concession were found to be in an unmodified state with instream and riparian habitats that were natural. A total of 43 different fish species were captured during the February 2015 survey which included 5 endemic species. The majority of the sampled species were found to be classified as “Least Concern” (40) with 4 “not evaluated” and 1 “data deficient” classification. An endemic assessment revealed a total of 30 endemic taxa expected to be present in the Boteka concession. Of the total expected endemic taxa, 28 are of “least concern” with 2 species “data deficient”. No Rare, Threatened or Endangered species were captured or expected within the Boteka oil palm concession. The presence of several endemic taxa resulted in the classification of the river systems considered as highly endemic. Furthermore, the presence of an abundance of juvenile fish species in the larger Western and Loleka Rivers provides an indication that the rivers are important nursery areas. Recommendations have been made to study further the smaller tributaries considered in this study as well as confirm the nursery function of the larger Western and Loleka Rivers. Additionally, it was found that, the current planting regime on the Boteka oil palm concession is adequate to allow for the presence of an effective buffer zone which has reduced the potential for aquatic ecological impacts by the agricultural activity. Digby Wells Environmental ii Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 TABLE OF CONTENTS 1 Introduction ....................................................................................................................... 1 1.1 2 Expertise of the Aquatic Specialist .......................................................................... 1 Methodology...................................................................................................................... 1 2.1 Surveys ................................................................................................................... 1 2.2 Water Quality .......................................................................................................... 2 2.3 Aquatic Habitat ........................................................................................................ 2 2.3.1 2.4 Fish ......................................................................................................................... 5 2.4.1 3 Intermediate Habitat Integrity Assessment........................................................ 2 Conservation Status and Expected Species ..................................................... 6 Study Sites, General Aquatic Habitat and Expected Diversity .......................................... 6 3.1 General Aquatic Habitat and Expected Diversity ..................................................... 6 3.2 Aquatic Habitat of the Boteka Concession ............................................................... 8 4 Results ............................................................................................................................ 13 4.1 Water quality ......................................................................................................... 14 4.2 Intermediate Habitat Assessment Index ................................................................ 14 4.2.1 Fish community assessment .......................................................................... 16 4.2.2 Endemic and Conservation Assessment ........................................................ 30 5 Discussion ....................................................................................................................... 31 5.1 Water quality ......................................................................................................... 31 5.2 Intermediate Habitat Integrity Assessment ............................................................ 32 5.3 Fish ....................................................................................................................... 34 5.3.1 Fish Community Assessment ......................................................................... 34 5.3.2 Endemic and Conservation Status Assessment ............................................. 35 6 Recommendations .......................................................................................................... 36 7 High Conservation Value related aspects ....................................................................... 36 8 Conclusions..................................................................................................................... 38 9 References ...................................................................................................................... 39 Digby Wells Environmental iii Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 LIST OF FIGURES Figure 3-1: Freshwater fish species richness of the various Freshwater Ecoregions of the world (Abel et al. 2008). ........................................................................................................ 7 Figure 3-2: Endemic freshwater fish species richness of the various Freshwater Ecoregions of the world (Abel et al. 2008). .............................................................................................. 7 Figure 3-3: Location of the aquatic sampling points for the Boteka aquatic survey (February 2015). ................................................................................................................................... 9 Figure 3-4: Thick detritus substrate observed in the smaller tributaries (BOT5, February 2015). ................................................................................................................................. 10 Figure 3-5: Extensive lily pads (Nymphaea sp.) observed in the Loleka River (February 2015). ................................................................................................................................. 11 Figure 3-6: Floodplains observed in the Western River (February 2015). ............................ 11 Figure 5-1: Barriers present on the Boteka concession (February 2015). ............................ 32 Figure 5-2: Man-made burrows, Boteka concession (February 2015). ................................ 33 Figure 5-3: Nets left permanently in the rivers, Boteka concession (February 2015). .......... 34 Figure 5-4: Small-mesh seine net used to catch juvenile/small fishes (February 2015) ....... 34 LIST OF TABLES Table 2-1: Criteria in the Assessment of Habitat Integrity (Kleynhans, 1996). ....................... 2 Table 2-2: Table giving descriptive classes for the assessment of modifications to habitat integrity (Kleynhans, 1996).................................................................................................... 3 Table 2-3: Criteria and weights used for the assessment of habitat integrity (Kleynhans, 1996). ................................................................................................................................... 4 Table 2-4: Intermediate habitat integrity assessment categories (Kleynhans, 1996). ............ 5 Table 3-1: Global Positioning System (GPS) co-ordinates for the aquatic sampling points of the Boteka oil palm concession (February 2015 survey). .................................................... 10 Table 3-2: General habitat photographs at each site during the February 2015 survey. ...... 12 Table 4-1: In situ water quality results obtained during the February 2015 survey for the Boteka concession. ............................................................................................................. 14 Table 4-2: The instream assessment for the Western River. ............................................... 14 Digby Wells Environmental iv Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Table 4-3: The riparian assessment for the Western River. ................................................. 15 Table 4-4: The instream assessment for the Loleka River. .................................................. 15 Table 4-5: The riparian assessment for the Loleka River. ................................................... 16 Table 4-6: Sampling effort, taxa sampled and Margalef’s richness index results obtained during the February 2015 survey......................................................................................... 17 Table 4-7: Photographs and conservation status of Captured Fish (February, 2015): {Not Evaluated (NE), Least Concern (LC), Data Deficient (DD)}. ................................................ 20 Table 4-8: Endemic taxa, their conservation status and distribution expected on the Boteka concession. ......................................................................................................................... 30 Table 7-1: High Conservation Values for freshwater systems (Brown et al., 2013).............. 37 LIST OF APPENDICES Appendix A: Fish community assessment Digby Wells Environmental v Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 1 Introduction The Feronia PHC (Feronia) business includes the restoration and operation of three Oil Palm concessions on the Congo River and its associated tributaries: in Lokutu (Orientale province), and Yaligimba and Boteka in Equateur Province. Feronia targets a RSPO (Roundtable on Sustainable Palm Oil) certification for its three concessions. Digby Wells Environmental (hereafter Digby Wells) was commissioned by Feronia to conduct aquatic ecological specialist studies on their Boteka oil palm concession in the central Congo basin, as part of an environmental assessment. The Congo River has the second greatest discharge of any river in the world (the Amazon River has the largest), with the central Congo basin being host to swamps and wetlands estimated to cover at least 120,000 km2. There is a generally poor scientific understanding of the aquatic ecology due to poor infrastructure, as well as socio-economic factors such as political instability and social unrest (Campbell, 2005). Based on observations made by Digby Wells, it is clear that the health of the aquatic ecosystems is currently threatened by activities which are causing loss of habitat and, therefore, aquatic biodiversity. The aim of this study was to establish the conservation value of the aquatic ecosystems associated with the oil palm concession. The assessment enabled the baseline condition of the rivers to be established and therefore, the current conservation status of the aquatic ecosystems. The objective of the study was to establish the current ecological status, degree of endemism, conservation status of species and overall conservation value of the river courses. This study forms a component of the overall biodiversity assessment incorporated into the High Conservation Value (HCV) assessment for the Boteka concession. 1.1 Expertise of the Aquatic Specialist Russell Tate is an aquatic ecologist in the Biophysical Department of Digby Wells, he is a Professional Natural Scientist who holds a Master’s degree in aquatic health from the University of Johannesburg (South Africa). Russell has published multiple scientific papers and has completed aquatic assessments in several African countries including Botswana, Democratic Republic of Congo (DRC), Mali, Senegal, Ivory Coast, South Africa, and Mozambique. He has carried out focused tropical assessments in Cameroon, Liberia and Ghana. 2 Methodology For ease of reading the methodology has been divided into subsections which deal with specific components. 2.1 Surveys A single survey was completed at the Boteka concession from the 6th to the 13th February 2015. This coincides with the lower flow period in DRC. The rationale for surveying at this Digby Wells Environmental 1 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 time of year is that the river systems on the Boteka concession would be flowing adequately (not flooding) which allows for effectively undertaking a biological assessment. 2.2 Water Quality Water quality was measured using a calibrated Extech DO 700 multimeter. In situ constituents considered in this study included temperature (ºC), pH, dissolved oxygen (mg/l) and conductivity (µS/cm). 2.3 Aquatic Habitat The availability and diversity of habitat is important to consider in assessments due to the reliance and adaptations of aquatic biota to specific habitats (Barbour et al., 1996). Habitat quality and availability assessments are usually conducted alongside biological assessments that utilise fish and macroinvertebrates. Aquatic habitat (habitat) was assessed through observations on each river system considered. The methods used for the assessment are set out by Bain and Stevenson (1990), Vannote et al., (1980), and Gerber and Gabriel (2002). The assessment and description of habitat in this study has been used to ascertain the potential presence of HCV/Rare, Threatened and Endangered (RTE) taxa. Furthermore, in order to determine the conservation value of the considered river systems, an assessment for the potential of “natural conditions” was completed (Brown et al., 2013). 2.3.1 Intermediate Habitat Integrity Assessment In order to define a general habitat, for baseline purposes, the instream and riparian habitat was assessed and characterised according to “Procedure for Rapid Determination of Resource Directed Measures for River Ecosystems (Section D), 1999”. The Intermediate Habitat Integrity Assessment (IHIA) model was used to assess the integrity of the habitats from a riparian and instream perspective. The habitat integrity of a river refers to the maintenance of a balanced composition of physico-chemical and habitat characteristics on a temporal and spatial scale that are comparable to the characteristics of natural habitats of the region (Kleynhans, 1996). The criteria utilised in the assessment of habitat integrity in the current study are presented in Table 2-1. Table 2-1: Criteria in the Assessment of Habitat Integrity (Kleynhans, 1996). Criterion Relevance Water abstraction Direct impact on habitat type, abundance and size. Also implicated in flow, bed, channel and water quality characteristics. Riparian vegetation may be influenced by a decrease in the supply of water. Flow modification Consequence of abstraction or regulation by impoundments. Changes in temporal and spatial characteristics of flow can have an impact on habitat attributes such as an increase in duration of low flow season, resulting in low availability of certain Digby Wells Environmental 2 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Criterion Relevance habitat types or water at the start of the breeding, flowering or growing season. Bed modification Regarded as the result of increased input of sediment from the catchment or a decrease in the ability of the river to transport sediment (Gordon et al., 1993). Indirect indications of sedimentation are stream bank and catchment erosion. Purposeful alteration of the stream bed, e.g. the removal of rapids for navigation (Hilden & Rapport, 1993) is also included. Channel modification May be the result of a change in flow, which may alter channel characteristics causing a change in marginal instream and riparian habitat. Purposeful channel modification to improve drainage is also included. Water quality modification Originates from point and diffuse point sources. Measured directly, or alternatively indicated by human settlements, agricultural and industrial activities. Aggravated by a decrease in the volume of water during low or no flow conditions. Inundation Destruction of riffle, rapid and riparian zone habitat. Obstruction to the movement of aquatic fauna and influences water quality and the movement of sediments (Gordon et al., 1992). Exotic macrophytes Alteration of habitat by obstruction of flow and may influence water quality. Dependent upon the species involved and scale of infestation. Exotic aquatic fauna The disturbance of the stream bottom during feeding may influence the water quality and increase turbidity. Dependent upon the species involved and their abundance. Solid waste disposal A direct anthropogenic impact which may alter habitat structurally. Also a general indication of the misuse and mismanagement of the river. Indigenous vegetation removal Impairment of the buffer the vegetation forms to the movement of sediment and other catchment runoff products into the river (Gordon et al., 1992). Refers to physical removal for farming, firewood and overgrazing. Exotic vegetation encroachment Excludes natural vegetation due to vigorous growth, causing bank instability and decreasing the buffering function of the riparian zone. Allochtonous organic matter input will also be changed. Riparian zone habitat diversity is also reduced. Bank erosion Decrease in bank stability will cause sedimentation and possible collapse of the river bank resulting in a loss or modification of both instream and riparian habitats. Increased erosion can be the result of natural vegetation removal, overgrazing or exotic vegetation encroachment. The relevant criteria is then weighted and scored according to Kleynhans (1996), as seen in the tables below (Table 2-2 and Table 2-3). Table 2-2: Table giving descriptive classes for the assessment of modifications to habitat integrity (Kleynhans, 1996). Digby Wells Environmental 3 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Impact Category Description Score None No discernible impact or the modification is located in such a way that it has no impact on habitat quality, diversity, size and variability. 0 Small The modification is limited to very few localities and the impact on habitat quality, diversity, size and variability are also very small. 1-5 Moderate The modifications are present at a small number of localities and the impact on habitat quality, diversity, size and variability are also limited. 6-10 Large The modification is generally present with a clearly detrimental impact on habitat quality, diversity, size and variability. Large areas are, however, not influenced. 11-15 Serious The modification is frequently present and the habitat quality, diversity, size and variability in almost the whole of the defined area are affected. Only small areas are not influenced. 16-20 Critical The modification is present overall with a high intensity. The habitat quality, diversity, size and variability in almost the whole of the defined section are influenced detrimentally. 21-25 Table 2-3: Criteria and weights used for the assessment of habitat integrity (Kleynhans, 1996). Instream Criteria Weight Riparian Zone Criteria Weight Water abstraction 14 Indigenous vegetation removal 13 Flow modification 13 Exotic vegetation encroachment 12 Bed modification 13 Bank erosion 14 Channel modification 13 Channel modification 12 Water quality 14 Water abstraction 13 Inundation 10 Inundation 11 Exotic macrophytes 9 Flow modification 12 Exotic fauna 8 Water quality 13 Solid waste disposal 6 TOTAL 100 TOTAL 100 Scores are then calculated based on ratings received from the assessment. The estimated impacts of the criteria are then summed and expressed as a percentage to arrive at a Digby Wells Environmental 4 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 provisional habitat integrity assessment. The scores are then placed into the intermediate habitat integrity assessment categories (Kleynhans, 1996) as seen in Table 2-4. It should be noted that the IHIA was based on regions assessed in the current studies and therefore may only constitute the assessment of conditions within a 50 km length of the considered water courses. Table 2-4: Intermediate habitat integrity assessment categories (Kleynhans, 1996). Category 2.4 Description Score A Unmodified, natural. 90-100 B Largely natural with few modifications. A small change in natural habitats and biota may have taken place but the ecosystem functions are essentially unchanged. 80-90 C Moderately modified. A loss and change of natural habitat and biota have occurred but the basic ecosystem functions are still predominantly unchanged. 60-79 D Largely modified. A large loss of natural habitat, biota and basic ecosystem functions has occurred. 40-59 E The loss of natural habitat, biota and basic ecosystem functions is extensive. 20-39 F Modifications have reached a critical level and the lotic system has been modified completely with an almost complete loss of natural habitat and biota. In the worst instances the basic ecosystem functions have been destroyed and the changes are irreversible. 0-19 Fish A variety of techniques were applied to sample fish species. The sampling methods depended on site characteristics and included cast nets, fyke nets, gill nets, angling and electro-fishing (Smith and Root LR-24). A quantitative and qualitative fish assessment was completed. Fish community structures and diversity were determined for each sampling site; this information was used to investigate basic community characteristics. The information and specific characteristics of dominant fish species, and the species occurring, allows for the analysis of the present ecological state of the aquatic ecosystem. The endemic and endangered species lists were compiled based on information from Fishbase (www.fishbase.org) and Eschemeyer (2012). The range distribution of species was taken from range maps of the International Union for Conserved Nature (IUCN) red list. Digby Wells Environmental 5 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Identification of fish was completed using Paugy et al. (2003), Skelton (2001) and Verlag (2004). Furthermore, photos were uploaded to the Africhthy website (https://www.flickr.com/groups/africhthy) in order to solicit further identification of species. 2.4.1 Conservation Status and Expected Species The conservation status of all captured fish species and those expected to be found during the assessment was compared with reference to the following: ■ IUCN (IUCN) Red list of threatened species (IUCN); ■ Fishbase (www.fishbase.org); and ■ Eschmeyer (2012). 3 3.1 Study Sites, General Aquatic Habitat and Expected Diversity General Aquatic Habitat and Expected Diversity The focus area for this study was approximately 16 km east of the town Ingende, Equateur province. The study considered tributaries of the Momboyo River. The Momboyo and Tshuapa rivers flow into the Ruki River which is a tributary of the Congo River. The study focus area is in the Cuvette Centrale freshwater Ecoregion (Thieme et al. 2005). Based on available desktop information, the major aquatic habitat type in this region is tropical/subtropical floodplain rivers with wetland complexes. The ecoregion has topography that is almost totally flat, at about 300 m above sea level. The climate of the ecoregion is characterised by an equatorial and wet climate with rainfall consistent almost year round. According to Theime et al. (2005), the average annual rainfall in the ecoregion is between 1,500 mm and 2,000 mm with mean annual temperatures at 24 ºC. The Cuvette Centrale freshwater ecoregion contains a variety of habitats which include: open waters, small streams, coves, meadows of aquatic vegetation, permanent swamps and extensive floodplains. In addition to physical habitats, floating Eichhornia masses are associated with this ecoregion. Seasonally flooded riparian zones are associated with this ecoregion which can result in permanent swamp forests with few dominant species but with rich floral diversity. According to Abel et al. (2008), the Cuvette Centrale freshwater ecoregion is host to a rich fish fauna with approximately 300 fish species (Figure 3-1) and 12 (known) taxa that are specifically endemic to the Cuvette Centrale freshwater ecoregion (Figure 3-2). Digby Wells Environmental 6 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Figure 3-1: Freshwater fish species richness of the various Freshwater Ecoregions of the world (Abel et al. 2008). Figure 3-2: Endemic freshwater fish species richness of the various Freshwater Ecoregions of the world (Abel et al. 2008). Digby Wells Environmental 7 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 It should be noted that although 300 taxa are expected to be present, only 240 species have been documented in scientific journals. A recent study of fishes of the Salonga National Park revealed the presence of 152 species within the immediate region (Iyaba and Stiassny, 2013). In general, the Cuvette Centrale freshwater ecoregion is considered to have a limited number of threatened taxa (Brooks et al. 2011). The main factor contributing to the low number of threatened taxa is the remote locations of tributaries (undisturbed areas). Furthermore, regional endemism is low due to the interconnected nature and historical climatic shifts of the of the Cuvette Centrale freshwaters (Iyaba and Stiassny, 2013). 3.2 Aquatic Habitat of the Boteka Concession A total of 6 sites were considered during the Boteka aquatic assessment (Figure 3-3 and Table 3-1)), with the specific details provided below for future assessments. Due to the timing the sites were selected in annual river systems and therefore non-perennial systems were not considered. Digby Wells Environmental 8 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Figure 3-3: Location of the aquatic sampling points for the Boteka aquatic survey (February 2015). Digby Wells Environmental 9 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Table 3-1: Global Positioning System (GPS) co-ordinates for the aquatic sampling points of the Boteka oil palm concession (February 2015 survey). Site GPS co-ordinate River Western River BOT1 -0.412968° 19.054632° BOT4 -0.444996° 19.065845° BOT5 -0.473760° 19.067043° River Loleka River BOT2 -0.483893° 19.200348° BOT3 -0.456719° 19.181370° BOT6 -0.459870° 19.146510° The sampling sites were selected on two separate tributaries of the Momboyo River; the Loleka River is the largest of the tributaries. All sites were found to be dominated by swamp habitats with limited flow and deep leafy detritus substrate (Figure 3-4). Figure 3-4: Thick detritus substrate observed in the smaller tributaries (BOT5, February 2015). The dominant aquatic habitats in the smaller tributaries were swamp conditions presenting abundant submerged root wads. In the larger tributaries different habitats types were observed and are described in the following sections. Deep channels and extensive Digby Wells Environmental 10 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 floodplains allowed for the proliferation of large areas of lily pads (Nymphaea sp.) (Figure 3-5). In the larger river systems (±15–20m width), large areas submerged swamp vegetation were observed. This habitat is likely flooded during the higher flow periods and will provide important breeding habitats for various fish species (Figure 3-6). The water column of the larger rivers was dark and tea coloured, which is attributed to the large amount of decaying detritus and swamp-like conditions. Table 3-2 presents photographs that illustrated the aquatic habitat for each study site (BOT1–BOT6); the biological assessment refers to each of these. Figure 3-5: Extensive lily pads (Nymphaea sp.) observed in the Loleka River (February 2015). Figure 3-6: Floodplains observed in the Western River (February 2015). Digby Wells Environmental 11 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Table 3-2: General habitat photographs at each site during the February 2015 survey. Site Photograph General Habitat BOT1 Swamp, Submerged vegetation and sandy substrate BOT2 Swamp, Submerged vegetation and sandy substrate BOT3 Sand, deep channels with detritus Digby Wells Environmental 12 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Site 4 Photograph General Habitat BOT4 Sand, deep detritus and roots BOT5 Sand, deep detritus and roots BOT6 Sand, deep detritus and roots Results The results section has is presented in the same layout as the methodology section above. Digby Wells Environmental 13 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 4.1 Water quality In situ water quality results from the February 2015 survey are presented in Table 4-1. Table 4-1: In situ water quality results obtained during the February 2015 survey for the Boteka concession. Constituent BOT1 BOT2 BOT3 BOT4 BOT5 BOT6 Temperature (ºC) 21 22 23 26 24 26 pH 4.2 4.5 4.1 4.6 4.8 4.8 Conductivity (µS/cm) 28 37 35 27 30 19 Dissolved oxygen (mg/l) 2.4 3.5 3.3 2.1 2.3 3.2 The results of the in situ analysis indicated that temperatures were consistent across the sites; ranging from 21 ºC at BOT1 to 26 ºC at BOT4 and BOT6. The power of hydrogen (pH) varied between 4.1 at BOT3 to 4.8 at BOT5 and BOT6. Dissolved solids, measured as electrical conductivity (µS/cm) ranged from a low of 19 µS/cm at BOT6 to 37 µS/cm at BOT2. Dissolved oxygen concentrations ranged from 2.1 mg/l at BOT4 to 3.5 mg/l BOT2. 4.2 Intermediate Habitat Assessment Index The intermediate habitat assessment was carried out in the Western and Loleka Rivers. The Western River included BOT1, BOT4 and BOT5; results are presented in Table 4-2 and Table 4-3. Table 4-2: The instream assessment for the Western River. Instream Average score Score Water abstraction 0 0 Flow modification 5 2.6 Bed modification 5 2.6 Channel modification 5 2.6 Water quality 1.6 0.9 Inundation 1.6 0.6 Exotic macrophytes 0 0 Digby Wells Environmental 14 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Instream Average score Score Exotic fauna 0 0 Solid waste disposal 0 0 Total Instream 90.6 Category class A Table 4-3: The riparian assessment for the Western River. Riparian Indigenous vegetation removal Exotic vegetation encroachment Average score Score 5 2.6 1 0.48 Bank erosion 0 0 Channel modification 1.6 0.8 Water abstraction 0 0 Inundation 1.6 0.8 Flow modification 2.6 1.28 Water quality 1.6 0.86 Total Riparian 93.2 Category class A The results of the IHIA show that instream and riparian habitat of the Western River is currently in an unmodified state (class A). Sites included in the Loleka River IHIA were BOT2, BOT3 and BOT6. The results of the assessment are presented in Table 4-4 and Table 4-5. Table 4-4: The instream assessment for the Loleka River. Instream Average score Score Water abstraction 0.00 0.00 Flow modification 5.00 2.60 Bed modification 3.33 1.73 Channel modification 1.67 0.87 Water quality 0.00 0.00 Digby Wells Environmental 15 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Instream Average score Score Inundation 1.67 0.67 Exotic macrophytes 0.00 0.00 Exotic fauna 0.00 0.00 Solid waste disposal 0.00 0.00 Total Instream 94 Category class A Table 4-5: The riparian assessment for the Loleka River. Riparian Indigenous vegetation removal Exotic vegetation encroachment Average score Score 1.67 0.8 1.67 0.8 Bank erosion 0.00 0 Channel modification 0.00 0 Water abstraction 0.00 0 Inundation 1.67 0.7 Flow modification 1.67 0.8 Water quality 0.00 0 Total Riparian 96.8 Category class A Considering the above results, it is clear that the instream and riparian habitat of the Loleka River system is in an unmodified status (class A). 4.2.1 Fish community assessment A total of 43 species were sampled during the February 2015 survey; results are presented in Table 4-6. Digby Wells Environmental 16 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Table 4-6: Sampling effort, taxa sampled and Margalef’s richness index results obtained during the February 2015 survey. Site Effort Species Amount Taxa Individual s Margalefs richness index Ctenopoma kingsleyae Aplocheilichthys brichardi Barbus holotaenia Brycinus imberi Ctenopoma gabonense Hemichromis bimaculatus BOT 1 Local gill nets Hemichromis elongatus N/A Hepsetus odoe Hylopanchax cf. silvestris Micralestes humilis Papyrocranus congoensis Petrocephalus cf. catostoma Tilapia cf. tholloni Alestes macrophthalmus Brycinus bimaculatus Bryconaethiops boulengeri Charra obscura Distichodus fasciolatus Distichodus fasciolatus BOT 2/3 Local gill nets Hepsetus odoe Macrusenius sp. N/A Mormyrops anguilloides Papyrocranus congoensis Polypterus weeksii Tilapia cf congica Distichodus fasciolatus Type 1. Digby Wells Environmental 17 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Site Effort Species Amount Taxa Individual s Margalefs richness index 13 62 2.9 11 79 2.2 12 117 2.3 Xenomystus nigri BOT 28 4 Minutes BOT 23 5 minutes BOT 38 6 minutes Digby Wells Environmental Xenomystus nigri 3 Aphyosemion cf. elegans 16 Barbus hulstaerti 6 Clarias theodorae 2 Epiplatys fasciatus 2 Hemichromis elongatus 4 Microctenopoma ansorgii 4 Microctenopoma sp1 1 Nanochromis teugelsi 3 Neolebias trewavasae 18 Parauchenoglanis ngamensis Schilbe marmoratus 1 Tilapia cf. cabrae 1 Channallabes apus 3 Aphyosemion cf. elegans 5 Barbus holotaenia 4 Barbus hulstaerti 43 Congochromis dimidiatus 5 Ctenopoma multispine 1 Epiplatys fasciatus 1 Hepsetus odoe 1 Microctenopoma ansorgii 6 Nanochromis teugelsi 9 Phractolaemus ansorgii 1 Channallabes apus 1 Aphyosemion cf. elegans 5 Barbus hulstaerti 62 1 18 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Site Effort Species Amount Clarias theodorae 4 Hemichromis elongatus 5 Epiplatys sp1. 1 Hepsetus odoe 5 Microctenopoma ansorgii 6 Microctenopoma fasciolatum 4 Nanochromis teugelsi 8 Neolebias trewavasae 15 Pantodon buchholzi 1 Taxa Individual s Margalefs richness index The results of the fish community assessment are provided in appendix A. The diversity of fish ranged at the sites (selected for quantitative sampling) from 11 species at BOT5 to 13 species at BOT4. Total individuals captured at the sites ranged from 62 at BOT4 to 117 at BOT6. The result of the Margalefs richness index showed ranges from 2.2 at BOT5 to 2.9 at BOT4. Photographs and the conservation status of the captured fish are presented in the table below (Table 4-7). Digby Wells Environmental 19 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Table 4-7: Photographs and conservation status of Captured Fish (February, 2015): {Not Evaluated (NE), Least Concern (LC), Data Deficient (DD)}. Species Photo Ctenopoma kingsleyae Native/Indigenous LC Ctenopoma gabonense Native/Indigenous NE Microctenopoma nanum Native/Indigenous LC Ctenopoma multispine Native/Indigenous LC Digby Wells Environmental 20 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Species Photo Microctenopoma ansorgii Native/Indigenous LC Microctenopoma fasciolatum Native/Indigenous LC Hemichromis bimaculatus Native/Indigenous LC Tilapia cf. tholloni Native/Indigenous LC Digby Wells Environmental 21 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Species Photo Tilapia cf congica Native/Indigenous LC Tilapia cf. cabrae Native/Indigenous LC Congochromis dimidiatus Native/Indigenous LC Digby Wells Environmental 22 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Species Photo Nanochromis teugelsi Native/Indigenous LC Petrocephalus cf. catostoma Native/Indigenous NE Marcusenius sp. Native/Indigenous NE Mormyrops anguilloides Native/Indigenous LC Xenomystus nigri Native/Indigenous LC Digby Wells Environmental 23 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Species Photo Papyrocranus congoensis Native/Indigenous LC Pantodon buchholzi Native/Indigenous LC Polypterus weeksii Native/Indigenous LC Parauchenoglanis ngamensis Native/Indigenous LC Phractolaemus ansorgii Native/Indigenous LC Digby Wells Environmental 24 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Species Photo Channallabes apus Native/Indigenous LC Clarias theodorae Native/Indigenous LC Charra obscura Native/Indigenous LC Schilbe marmoratus Native/Indigenous LC Epiplatys sp1. N/A N/A Digby Wells Environmental 25 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Species Photo Epiplatys fasciatus Native/Indigenous NE Aphyosemion elegans Native/Indigenous LC Neolebias trilineatus Endemic LC Neolebias trewavasae Native/Indigenous LC Digby Wells Environmental 26 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Species Photo Hylopanchax cf. silvestris Endemic NE Aplocheilichthys brichardi Endemic LC Barbus holotaenia Native/Indigenous LC Barbus hulstaerti Endemic LC Digby Wells Environmental 27 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Species Photo Distichodus fasciolatus Type 1. Native/Indigenous LC Distichodus fasciolatus Native/Indigenous LC Hepsetus odoe Native/Indigenous LC Brycinus bimaculatus Endemic LC Digby Wells Environmental 28 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Species Photo Brycinus imberi Native/Indigenous LC Micralestes humilis Native/Indigenous LC Bryconaethiops boulengeri Native LC Alestes macrophthalmus Native/Indigenous LC Hemichromis elongatus Native LC Digby Wells Environmental 29 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 A total of 43 species were captured during the assessment. Five endemic species were captured. The majority of the sampled species were classified as “Least Concern” (40) with 4 “not evaluated” and 1 “data deficient” classification (IUCN, 2015). 4.2.2 Endemic and Conservation Assessment The results of the assessment for potential endemic species are presented in Table 4-8. Table 4-8: Endemic taxa, their conservation status and distribution expected on the Boteka concession. Species Conservation Status Distribution Aplocheilichthys brichardi LC Regional Barbus hulstaerti Barbus matthesi Brycinus bimaculatus Clariallabes centralis Congocharax olbrechtsi Ctenopoma weeksii LC LC LC LC LC LC Regional Regional National Regional Regional National Distichodus decemmaculatus LC Regional Dolichallabes microphthalmus LC Regional Hemistichodus lootensi LC Regional Hemistichodus mesmaekersi LC Regional Marcusenius ghesquierei LC Regional Marcusenius kutuensis Micralestes congicus LC LC Regional Regional Microstomatichthyoborus bashforddeani LC National Nannothrissa parva Neolebias gracilis Neolebias trilineatus Paradoxoglanis parvus LC DD LC LC Regional Local National National Phenacogrammus deheyni LC Regional Phenacogrammus interruptus LC National Phenacogrammus polli Phractura lindica Pollimyrus schreyeni LC LC LC Regional National Regional Digby Wells Environmental 30 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Species Conservation Status Distribution Stomatorhinus fuliginosus LC Regional Stomatorhinus patrizii Synodontis aterrimus LC LC Regional Regional Synodontis camelopardalis DD Regional Tricuspidalestes caeruleus LC Regional Tylochromis aristoma LC Regional Least Concern (LC) and Data Deficient (DD). National labels refer to the distribution range lying over the upper, middle or lower Congo basin. Regional labels refer to the taxa being defined to the middle and/or upper Congo basin. Based on the results of the endemic assessment completed by Digby Wells, a total of 30 endemic taxa are expected to be present in the Boteka concession. According to the IUCN Red list, 28 of the expected taxa are considered to be of “least concern” with 2 species “data deficient”. When considering the total list of endangered taxa in the DRC, no RTE taxa are expected to be present on the Boteka concession. 5 Discussion For ease of understanding and navigation the discussion has been divided as per the methodology and results sections above. 5.1 Water quality In summary, water quality analyses are as follows: ■ The water temperature of the rivers in the Boteka concession averaged around 23ºC. These are natural temperatures when considering the habitat type is tropical streams. ■ The pH was found to be relatively consistent within the rivers of the Boteka concession. The majority of the sites had slightly acidic pH levels (4-5). The acidic nature of the sites are likely due to the decomposition of allochthonous material and seepage of plant derived acids/tannins and other chemicals from decaying leafy material, these pH levels are therefore seen as natural (Deano and Robinson, 1985). ■ Dissolved solids, measured as conductivity, were in notably low concentrations on the Boteka concession with the highest levels recorded at BOT2. These low concentrations show that anthropogenic activities on the concession do not contribute a large amount of solutes to the local river systems. In addition, these low dissolved solid concentrations indicate the large degree of dilution capacity available in these local river systems and illustrate typical and natural tropical conditions (Balek, 1983). Digby Wells Environmental 31 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 ■ Dissolved oxygen concentrations were low which is typical of low gradient swampy habitats. These low concentrations are a result of the reducing environment, caused by the removal of oxygen by decaying organic matter and are, therefore, viewed as natural. In conclusion, water quality results illustrate conditions which would be expected when assessing a tropical river system. 5.2 Intermediate Habitat Integrity Assessment The integrity of aquatic habitats has a direct impact on the aquatic biota (certain species are more sensitive than others). When considering the results obtained for the IHIA for the Western River system, modification was found to be “uncommon” in terms of the habitat model. Man-made barriers (Figure 5-1) and burrows (Figure 5-2) were found near villages on the Boteka concession; it is assumed such barriers are only near villages and so have a little impact. The barriers and burrows are used to attract larger fishes which are captured using hooks and lines, or gill nets. These instream impacts are viewed as temporary as they are washed away in heavy rain. Figure 5-1: Barriers present on the Boteka concession (February 2015). Communities use the rivers for bathing and general washing (laundry and cooking utensils) which has caused deterioration of water quality. However, this has been assessed as having a small impact because contamination is diluted and sediments are disturbed but settle downstream. The overall status of the instream habitat of the Western River was found to be unmodified (class A); anthropogenic impacts in the river system are infrequent. Digby Wells Environmental 32 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Figure 5-2: Man-made burrows, Boteka concession (February 2015). The riparian habitat assessment for the Western River showed it was in natural state (class A). Removal of indigenous vegetation in the buffer zone of tributaries was assessed as having a small impact in the Western River riparian habitat. It was concluded the impact was small due to riparian areas being remote and inaccessible. In conclusion, the habitat of the Western River was natural with isolated impacts attributed to activities such as barriers, washing and fishing are all small impacts. The Loleka River instream habitat assessment had similar results to that of the Western River: ■ The presence of infrequent and small impacts resulted in the unmodified classification (class A). ■ The riparian habitat of the Loleka River is unmodified (class A) with no discernible impacts to the riparian conditions of the river system. Fishing and associated activities are placing pressure on local fish resources (e.g. gill nets are left in many places (Figure 5-3)). Furthermore, local fishing techniques include small mesh seine nets which are used to capture the abundant small fish (Figure 5-4). These small fish are predominantly juvenile fish or fry which are using cover, created by the swamp, as a nursery. It is unlikely that the fishing impacts would have a negative impact on aquatic habitat, but the impact on local fish communities would be large. Digby Wells Environmental 33 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Figure 5-3: Nets left permanently in the rivers, Boteka concession (February 2015). Figure 5-4: Small-mesh seine net used to catch juvenile/small fishes (February 2015) 5.3 Fish 5.3.1 Fish Community Assessment Ichthyological surveys in the Congo River basin have mostly focused on the main stems of the large river systems. Therefore, there is very little information on the fish communities of smaller tributaries (Brooks et al. 2011). Thus, this study and the description of the community structures in small tributaries provide important baseline information for management, monitoring and conservation. The most abundant fish captured was the endemic species Barbus hulstaerti with 111 individuals captured during the survey. This small Barb inhabits shallow rainforest streams and swamps with dense marginal vegetation. During electrofishing the species was Digby Wells Environmental 34 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 encountered as large shoals which were under the ample submerged vegetation. The species is classified as least concern due to its wide distribution and lack of major threats. The second most abundant species captured was Neolebias trewavasae. This distichodontid fish is known to occur in central Africa and has a wide distribution. This species was electrofished in the small impoundments created by the local people; the fish were in shoals along with Barbus hulstaerti. The third-most abundant species sampled was Aphyosemion cf. elegans. This species prefers shallow rainforest streams with full cover and submerged vegetation. The species was sampled in abundance in the small streams throughout the Boteka concession. The species is considered to be an indicator of riparian integrity due to its reliance on the rainforest canopy for cover (Toham and Teugels, 1999). The conservation status of the species is least concern due to its wide distribution and lack of serious threats. When the dominant taxa are compared to a recent study completed in several larger rivers upstream of the study area, clear differences are noted (Inogwabini, 2005). Dominant taxa in the study consisted of small fishes with adaptations to shallow swamps and full canopy cover whereas dominant taxa in the study by Inogwabini (2005) comprised taxa adapted to deeper waters (Synodontis and Auchenoglianus). The dominance of species adapted to rainforest (full cover) conditions illustrates the largely natural status of the riparian zones in the Boteka concession. Thus, it is apparent that the current management measures, in terms of the layout of oil palms, are sufficient to support buffer zones of riparian habitat. These intact buffer zones reduce potential impacts on water quality and sedimentation on the main reaches of the rivers within the Boteka concessions. The highest diversity of fishes was observed at BOT4 and, based on the community structure, the site also received the highest richness score. The increased diversity at the site is thought to be a result of the variety of habitat created through man-made burrows which is the ideal habitat for species such as Xenomystus nigri and Schilbe marmoratus which prefer darker and deeper habitats, respectively. At BOT5 and BOT6, the predatory Hepsetus odoe was captured illustrating the overall complete nature of the fish communities on the Boteka concession. In addition, an interesting species Phractolaemus ansorgii was captured during the survey; it is adapted to low oxygen habitats and supports the in situ oxygen water quality data findings. During the survey an abundance of juvenile fish were observed in the larger river systems, including the Western and Loleka Rivers. The presence of these juveniles indicates that the tributaries are nursery areas and are of great importance. 5.3.2 Endemic and Conservation Status Assessment The assessment of potential endemic fish in the Boteka concession revealed that 30 endemic taxa may be present. Five of these were confirmed by Digby Wells. The majority of the endemic species captured are small species specialised and adapted to rainforest conditions. In addition to the five endemic taxa, an additional four species are possibly Digby Wells Environmental 35 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 restricted to the Ruki River. However, due to the large area of the Ruki River, the endemic species are still considered to be regionally endemic by Digby Wells. The majority of the expected endemic taxa are regionally endemic and have a “least concern” conservation status. The central cause for the regional endemism can be linked to the interconnected nature of the central Congo basin. It is a result of “repeated climatic shifts resulting in fluctuating forest contraction and expansion since the Middle Pleistocene” (Iyaba and Stiassny, 2013). Threats to fish species within the Middle Congo River basin are few because of the inaccessible nature of the flooded wetlands and forests. However, according to Brooks et al. (2011) in the early 1990s, 37% of the total exploitable rainforest had been designated as timber concessions. Thus forestry and associated sedimentation could present a limiting factor and potential threat to fish species in the future. Further threats to fish species in the Middle Congo River include extensive fishing as observed during this study. Although threats to the fish species are currently increasing, due to the wide distributions and high levels of interconnectivity between the various freshwater regions in the Congo River basin, the effect of these potentially threatening activities on a larger scale (during the present-day) do not present serious threats to the fish communities in the Ruki River drainage. Overall it was found by Digby Wells that the fish in the river systems in the Boteka concession are regarded as endemic and the larger Western and Loleka Rivers are important nursery areas. 6 Recommendations Based on the results of this study the following recommendations can be made: ■ Future studies should focus on the smaller tributaries on the Boteka Concession. Furthermore, the nursery status of the larger rivers associated with the concession should be investigated further. ■ Migratory and temporal use of the rivers in the Boteka concession by aquatic ecology should be investigated further and the nursery status of the larger rivers confirmed. ■ The current activities by local communities have had limited effects on the ecological status of the rivers on the Boteka concession. Excessive netting with small mesh sizes was also observed. It is recommended that future studies assess the impacts of these activities. ■ The current riparian buffer zones in place between the oil palm plantations and the local river systems should be maintained. 7 High Conservation Value related aspects The guidelines listed in Brown et al. (2013) were used to derive Table 7-1. It should be noted that the table has only been populated based on the preliminary findings of this report; detailed information is presented in the HCV report (Digby Wells, 20151). Digby Wells Environmental 36 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Table 7-1: High Conservation Values for freshwater systems (Brown et al., 2013). HCV1 Present/absent Rationality Presence of RTE species Absent Not found to be present in studies Presence of protected areas for RTE taxa Absent Not within study focus area Presence of endemic, highly range limited species Absent Wide range of endemic species Critical dispersal routes for fish Absent Not major river systems HCV2 Present/absent Rationality Rivers with natural flow regimes Present Unmodified systems Rivers without downstream and upstream barriers Present Unmodified systems Unmodified river channels Present Unmodified systems Unmodified thermal, sediment and nutrient regimes Present Unmodified systems Land cover conversion below threshold of concern Not considered Not considered Rivers without invasive taxa Possible Invasive taxa not observed HCV3 Present/absent Rationality Rare, threatened or endangered freshwater ecosystems Absent Not unique or rare HCV4 Present/absent Rationality Floodplains and wetlands Present Floodplains present Digby Wells Environmental 37 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Riparian forests Present Observed on site Unleveed floodplains Present Observed on site Areas with a critical recharging effect on aquifers used for potable water Absent Not observed High surface water yield areas Present Not unique/uncommon Vegetated areas upstream of critical water supplies Present Not unique/uncommon HCV5 Present/absent Rationality Water sources necessary for access to basic drinking water and sanitation Present Observed on site Freshwater animal populations relied upon by local communities Present Observed on site HCV6 Present/absent Rationality Water bodies of high religious or cultural significance Digby Wells, 20152 Digby Wells, 20152 Freshwater products with cultural values Digby Wells, 20152 Digby Wells, 20152 8 Conclusions The conclusions to the studies are: ■ The assessment of aquatic ecological conditions in the rivers associated with the Boteka concession revealed the systems are unmodified and near natural condition. ■ Biological assessments revealed a largely intact riparian zone in the rivers considered. ■ There is sufficient buffer capacity between oil palm plantations and the considered river systems to promote and maintain typical tropical riparian habitats which will allow for the proliferation of natural species. ■ The assessment for RTE ichthyofaunal taxa revealed the general absence of endangered fish species in the Boteka concession. Digby Wells Environmental 38 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 ■ The assessment for endemic fish taxa revealed that endemic taxa would be expected and confirmed the high level of endemism on the Boteka concession. ■ Further assessment by Digby Wells revealed that the endemic taxa expected and confirmed to be present, have wide distributions and are considered least concern in terms of conservation statuses. 9 References Abel R, Thieme ML, Revenga C, Bryer M, Kottelat M, Bogutskaya N, Coad B, Mandrak N, Contreras Balderas S, Biussing W, Stiassny MLJ, Skelton P, Allen GR, Unmack P, Naseka A, Ng R, Sindorf N, Robertson J, Armijo E, Higgins JV, Heibel TJ, Wikramanayake E, Olson D, Lopez HL, Reis RE, Lundberg JG, Mark H, Perez S, Petry P. 2008. Freshwater Ecoregions of the World: A new map for biogeographic units for freshwater biodiversity conservation. Bioscience. 58:403–414. Bain MB, Stevenson N. 1999. Aquatic habitat assessment: Common methods, American Fisheries Society, Bethesda, Maryland. Balek J. 1983. Hydrology and water resources in tropical regions. Elsevier Science. Amsterdam, Netherlands. Barbour MT, Gerritsen J, White JS. 1996. Development of a stream condition index (SCI) for Florida. Florida Department of Environmental Protection: Tallahassee, Florida. Brooks EGE, Allen DJ, Darwall WRT. 2011. The status and distribution of freshwater biodiversity in central Africa. IUCN. Cambridge. United Kingdom. Brown E, Dudley N, Lindhe A, Muhtanian DR, Stewart C, Synnott T. 2013. Common guidance for the identification of High Conservation Values. HCV Resource Network. Campbell D. 2005. The World’s Largest Wetlands: Ecology and Conservation. Cambridge University Press. Deano PM, Robinson JW. 1985. The effect of decaying leaves on the pH and buffer capacity of water. Journal of Environmental Science and Health. 20: 903–911. Digby Wells Environmental 1. 2015 High Conservation Value Assessment, Lokutu Oil Palm Concession, CDC2950. Digby Wells Environmental2. 2015. Social Assessment for Feronia PHC’s Oil Palm Plantations in the Democratic Republic of Congo, Stakeholder Engagement Plan. CDC2950. Eschmeyer, WN. 2012. Catalog of Fishes. Electronic database accessible at http://research.calacademy.org/ichthyology/catalog/fishcatmain. asp accessed May 2015. Fishbase. 2015. Available at: http://www.fishbase.org/. Accessed 2015/04/14. Gerber A, Gabriel MJM. 2002. Aquatic Invertebrates of South African Rivers: Field Guide. Institute for Water Quality Services, Department of Water Affairs and Forestry, Pretoria. Hellawell K. 1977. Biological surveillance and water quality monitoring. Biological monitoring of inland fisheries. 69–88. Digby Wells Environmental 39 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Inogwabini BI. 2005. Fishes of the Salonga National Park, Democratic Republic of Congo: Survey and conservation issues. Orxy, 39: 78–81. IUCN. 2015. Available at http://www.iucnredlist.org/details/181572/0. Accessed 2015/04/14. Iyaba RJCM, Stiassny MLJ. 2013. Fishes of the Salonga National Park (Congo basin, central Africa)): A list of species collected in the Luilaka, Salonga, and Yenge Rivers (Equateur Province, Democratic Republic of Congo). Checklist 9: 246–256. Kleynhans CJ. 1996 A qualitative procedure for the assessment of the habitat integrity status of the Luvuvhu River. Journal of Aquatic Ecosystem Health 5: 41–54. Margalef R. 1961. Information Theory in Ecology. General Systems 3: 36–71. McMillan PH, 1998. An integrated habitat assessment system (IHAS v2) for the rapid biological assessment of rivers and streams. Division of the Environment and Forestry Technology, Report No. ENV-P-`I 98132. CSIR, Pretoria. Palmer RW, Taylor ED. 2004. The Namibian Scoring System (NASS) version 2 rapid bioassessment method for rivers. African journal of aquatic science. 29: 229–234. Paugy D, Leveque C, Teugels GG, Bigorne R, Romand R. 1990. Freshwater fishes of Sierra Leone and Liberia: Annotated checklist and distribution. Revision Hydrobiology tropical. 23: 329–350. Rowntree KM, Ziervogel G. 1999. Development of an index of stream geomorphology for the assessment of river health. National Aquatic Ecosystem Biomonitoring Programme. Report Series No.7. Skelton PH. 2001. A Complete Guide to the Freshwater Fishes of Southern Africa. Struik Publishers, Cape Town, South Africa. Thieme ML, Abell R, Stiassny MLJ, Skelton P. 2005. Freshwater Ecoregions of Africa and Madagascar: A Conservation Assessment. World Wildlife Fund. Toham AK, Teugels GG. 1999. First data on an Index of Biotic Integrity (IBI) based on fish assemblages for the assessment of the impact of deforestation in a tropical West African river system. Hydrobiologia. 397: 29–38. United States Environmental Protection Agency. 2006. Wadeable streams assessment: A collaborative survey of the nation’s streams. EPA/841/B-06/002. Vannote RL, Minshall GW, Cummins KW, Sedell JR Cushing CE. 1980. The River Continuum Concept. Canadian Journal of fisheries and Aquatic Science. 37: 130–137. Verlag BS. 2004.The Cichlid Fishes of Western Africa. First edition. Germany. Digby Wells Environmental 40 Aquatic Ecology Aquatic Ecology Assessment at Boteka CDC2950 Appendix A: Fish community assessment Aquatic Ecology Aquatic Assessment at Boteka CDC2950 Taxa Xenomystus nigri Aphyosemion cf. elegans Barbus hulstaerti Clarias theodorae Epiplatys fasciatus Hemichromis fasciatus Microctenopoma ansorgii Microctenopoma sp1 Nanochromis squamiceps Neolebias gracilis Parauchenoglanis ngamensis Schilbe cf. uranoscopus Figure 1-1: BOT4 fish community assessment. Taxa Channallabes apus Aphyosemion cf. elegans Barbus holotaenia Barbus hulstaerti Chromidotilapia cf. schoutedeni Ctenopoma multispine Epiplatys fasciatus Hepsetus odoe Microctenopoma ansorgii Nanochromis squamiceps Phractolaemus ansorgii Figure 1-2: BOT5 fish community assessment. Digby Wells Environmental 2 Aquatic Ecology Aquatic Assessment at Boteka CDC2950 Taxa Channallabes apus Aphyosemion cf. elegans Barbus hulstaerti Clarias theodorae Epiplatys fasciatus Epiplatys sp1. Hepsetus odoe Microctenopoma ansorgii Microctenopoma fasciolatum Nanochromis cf. squamiceps Neolebias gracilis Pantodon buchholzi Figure 1-3: BOT6 fish community assessment. Digby Wells Environmental 3