osicon-15 - Ocean Society of India

Transcription

th
4 National Conference of
Ocean Society of India
OSICON-15
OCEANIC PROCESSES ALONG THE COASTS OF INDIA
22-24 March 2015
CHAIRMAN
CONVENER
CO-CONVENER
TREASURER
Dr. S. W. A. NAQVI
Dr. V. RAMASWAMY
Dr. JAYA KUMAR SEELAM
Dr. A. S. UNNIKRISHNAN
CSIR-National Institute of Oceanography
Dona Paula, Goa - 403 004
INDIA
4th National Conference of Ocean Society of India
OSICON-15
22-24 March 2015
CSIR-National Institute of Oceanography, Goa, INDIA
OSI is grateful to follwoing valued sponsors for their generous
support for OSICON-15
Ministry of Earth Sciences
Prithvi Bhavan,
Lodhi Road,
New Delhi - 110003
Ministry of Earth Sciences
Government of India
Naval Research Board
Defense R&D Organization
Ministry of Defense
Government of India
Rajaji marg, New Delhi 110011
Department of Science, Technology &
Environment, Govt. of Goa.
Opp. Saligao Seminary,
Saligao, Bardez, Goa - 403511.
Department of Science, Technology &
Environment, Govt. of Goa
Science and Engineering Research Board
(SERB)
Department of Science and Technology (DST)
Government of India
Science and Engineering Research
Board, DST, Govt. of India
5 & 5A, Lower Ground Floor
Vasant Square Mall
Sector-B, Pocket-5
Vasant Kunj
New Delhi – 110 070
National Centre For Antarctic And
Ocean Research
Ministry of Earth Sciences, Government of
India, Headland Sada, Vasco-da-Gama,
Goa 403 804,
Indian National Centre for Ocean
Information Services ,
"Ocean Valley", Pragathi Nagar (BO),
Nizampet (SO), Hyderabad-500090
Adani Ports and Special Economic Zone
Limited.
1st floor, APSEZL house, Navrangpura ,
Ahmedabad 380 009, Gujarat
OSICON-15
22-24 March 2015
CONTENTS
SPONSORS
ii
ABOUT OCEAN SOCIETY OF INDIAN
iv
ABOUT OSICON-15
v
ABOUT CSIR-NIO
vi
COMMITTEES
ix
LIST OF ABSTRACTS
xi
ABSTRACTS
xxii
SESSION-01
1
SESSION-02
45
SESSION-03
113
SESSION-04
143
SESSION-05
177
SESSION-06
237
ADVERTISEMENTS
293
AUTHOR INDEX
295
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OSICON-15
22-24 March 2015
ABOUT OCEAN SOCIETY OF INDIA
Ocean Society of India (OSI) is a registered professional society registered in Kochi,
launched on March 19, 2006, with primary objective to strive for the advancement and
dissemination of knowledge in science, technology, engineering and allied fields related to
oceans. OSI endeavors to provide a forum for sharing the knowledge and experience of
individuals, scientific institutions and industrial organization for promoting the said
objectives and act as a link among academic and R&D institutions, national policy making
bodies, operational organizations and ocean industries by organizing programs such as
courses, lectures, workshops, symposia and topical reviews. OSI is a non-profit organization
devoted to excellence in science, engineering, technology and allied fields related to Ocean.
OSI is 9 years old and has a total of 450 members with its Life Members being more
than 325, 120 student members and about 5 annual members. OSI membership has grown
strongly during the recent years and is gaining strength with the active support received
from the ocean science, technology and engineering community. OSI has life members
located in all parts of India. So far three conferences i.e., OSICON-09; OSICON-11 and
OSICON-13 were held in Visakhapatnam, Chennai and Pune respectively. The OSICON-15 is
the fourth edition of the OSI conferences.
The OSI has is governed by the Governing Council (GC) elected by Members of the OSI.
The current GC consists of the following members:
Dr. S.W.A. Naqvi, Director, CSIR-NIO
Dr. M. Baba, Former Director, CESS
Dr. C. Gnanaseelan, IITM, Pune
Dr. V. Ramaswamy, CSIR-NIO, Goa
Dr. K.V.S.R. Prasad, Andhra Univ.
Dr. B.K. Jena, NIOT, Chennai
Dr. A.S. Unnikrishnan, CSIR-NIO, Goa
Dr. M.R. Ramesh Kumar, CSIR-NIO, Goa
Dr. Jaya kumar Seelam, CSIR-NIO, Goa
Dr. Milind Mujumdar, IITM, Pune
Dr. Roxy Mathew Koll, IITM, Pune
Dr. C.V.K. Prasada Rao, Ex-NPOL, Kochi
Dr. P. Anand, NPOL, Kochi
Dr. K.V. Jayachandran, KUFOS(FRM&HT), Kochi
Dr. A.D. Rao, IIT-Delhi
Dr. P.V. Joseph, Former Director IMD
Dr. C. Revichandran, CSIR-NIO-RC, Kochi
ii
President
Vice-President
Vice-President
Gen. Secretary
Joint Secretary
Joint Secretary
Treasurer
Member
Member
Member
Member
Member
Member
Member
Member
Ex-officio Member
Ex-officio Member
OSICON-15
22-24 March 2015
ABOUT OSICON-15
th
The 4 national conference of the OSI (OSICON-15) is scheduled to be held at National
Institute of Oceanography, Goa during 22-24 March 2015. The main thrust for this
conference would be “Oceanic Processes along the Coasts of India”. OSICON-15 provides a
forum to bring together scientists, academicians, researchers, engineers, technologists and
all other personnel in the marine related fields to share their knowledge for the benefit of
mankind. As it was done in the case of previous OSICONs, research contributions were
solicited as abstracts for OSICON-15 through e-mail. OSICON-15 invited active participation
from all branches of marine sciences, engineering and technologies and received
overwhelming response.
Keeping the focus on “Oceanic Processes along the Coasts of India”, abstracts were
invited on topics of interest to Ocean Scientists / Academicians /Engineers and
Technologists in the following areas:
Session No.
Topic
01
Ocean Biogeochemistry
02
Indian Ocean Variability
and Indian monsoon
03
Ocean Technology and
acoustics
04
Marine Geosciences
05
Coastal Processes
06
Marine Biology
Session Conveners
Dr. S. Prasanna Kumar, CSIR-NIO
Dr. VVSS Sarma, CSIR-NIO
Dr. TM Balakrishnan Nair, INCOIS
Dr. Gnanaseelan, IITM
Dr. Milind Mujumdar, IITM
Dr. PV Hareesh Kumar, NPOL
Dr. MR Ramesh Kumar, CSIR-NIO
Mr. R Madhan, CSIR -NIO
Mr. P Maurya CSIR-NIO
Dr. R Venkatesan, NIOT
Dr. CVK Prasada Rao, Former NPOL
Dr. B Nagender Nath, CSIR -NIO
Dr. A Mazumdar CSIR-NIO
Dr. AK Chaubey, CSIR-NIO
Dr Kamesh Raju, CSIR-NIO
Dr. M Baba, Former Director CESS
Dr. AS Unnikrishnan CSIR-NIO
Dr. Jaya Kumar Seelam, CSIR-NIO
Dr. BK Jena, NIOT
Dr. N Ramaiah, CSIR-NIO
Dr. AC Anil, CSIR-NIO
Dr KV Jayachandran, KUFOS, Kochi
A total of 225 abstracts were selected from about 230+ abstracts received and out of
these select abstracts were considered for oral presentation and remaining for Poster
presentation. About 140 poster and 85 oral presentations are scheduled during this
OSICON-15.
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OSICON-15
22-24 March 2015
CSIR-NATIONAL INSTITUTE OF OCEANOGRAPHY
DONA PAULA, GOA, INDIA
(A constituent laboratory of Council of Scientific and Industrial Research)
CSIR- National Institute of Oceanography (NIO) with its headquarters at Dona Paula, Goa, and
regional centres at Kochi, Mumbai and Visakhapatnam, is one of the 37 constituent laboratories of
the Council of Scientific & Industrial Research (CSIR).
NIO was established on 1 January 1966 following the International Indian Ocean Expedition (IIOE)
that was undertaken from 1962 to 1965.
The mission of CSIR-NIO is:
“To continuously improve our understanding of the seas around us and to translate this knowledge
to benefit all”.
Research and development
The major research areas include the four traditional branches of oceanography - biology,
chemistry, physics and geology &geophysics, besides ocean engineering, marine instrumentation
and archaeology. The major thrust areas for research are:
 Ocean Science towards Forecasting Indian Marine Living Resource Potential
 Geological Processes in the Indian Ocean – Understanding the Input Fluxes, Sinks and
Paleoceanography
 Geo-scientific Investigations for Deciphering the Earth’s Internal Processes and Exploration
of Energy Resources
 Indian Aquatic Ecosystems: Impact of Deoxygenation, Eutrophication and Acidification
 Analyses and Harnessing of Marine Biodiversity for Bioremediation of Aquaculture and
Other Industrial Effluents
 Impact of Natural and Anthropogenic Stresses on the Coastal Environment of India
 Geological and Geophysical Studies of Coastal Zone of India
 Development of Autonomous Platform/s for Ocean Applications
 Marine Ecological Assessment and Studies for Sustainable Development in the Coastal and
Shelf Areas alongWest Coast of India
 Ecobiogeography and Biotechnology of Estuaries and Coastal Waters of India
 Coastal Processes and Tectonics of Eastern Continental Margin of India
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OSICON-15
22-24 March 2015
Industry and society
CSIR-NIO provides services to industry and society through projects related to ports & harbours, oil
& gas companies, power plants, chemical & pharmaceutical companies that use the water front
for their marine facilities, which necessitate systematic study of the coastal environment.
NIO provides services in the following areas:
• Bathymetry, shallow seismic and side scan
sonar surveys
• Collection of shallow core samples
• Geo-technical investigations
• Studies related to coastal zone Management
• Delineation of Coastal Regulation Zone
• Environmental Impact Assessment
• Environmental monitoring
• Simulation of Met & Oceanographic parameters
based on numerical modelling
• Oil spill prediction and risk analysis and
preparation of contingency plan
• Identification of suitable sites for marine facilities
• Feasibility studies for marine facilities
• Oceanographic design parameters for marine facilities
• Testing of oil spill dispersants
• Underwater inspection
Research facilities:
CSIR-NIO uses 2 of its own research vessels – Sindhu Sankalp and Sindhu Sadhana besides other
research vessels for scientific expeditions.
CSIR-NIO offers state of the art analytical instruments
The library of CSIR-NIO is recognized as the National Information Centre for Marine Sciences
Research achievements:
CSIR-NIO contributes more than 200 scientific publications annually in reputed national and
international journals many of which have high impact factor.
CSIR-NIO scientists have filed several patents on inventions based on research carried out at the
Institute.
Outreach activities:
Training programs – CSIR-NIO conducts training programs for national and international agencies
catering to students, researchers, professionals and government officials.
Student programs – students from India and overseas can enrol in several programs (visit:
www.nio.org)
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OSICON-15
22-24 March 2015
vi
OSICON-15
22-24 March 2015
LOCAL ORGANISING COMMITTEES
Core-Committee:
S.W.A Naqvi - Chairman
M.R. Ramesh Kumar
P.S. Rao
B. Nagender Nath
A.C. Anil
S. Prasanna Kumar
N. Ramaiah
A.S. Unnikrishnan
C. Revichandran
A.K. Chaubey
Rahul Sharma
P.M. Muraleedharan
V. Sanil Kumar
Jaya Kumar Seelam
V. Ramaswamy - Convener
Protocol committee:
Rajiv Nigam - Chairman
P.S.Parameswaran
M. R. Ramesh Kumar
P. Vethamony
N. Ramaiah
A. K. Saran
A. C. Anil
Rahul Sharma - Convener
Venue & Sessions Committee:
Rahul Sharma - Chairman
D.M. Shenoy
A.P. Selvam
Sharon Tracy Gomes
Sundaresh
Areef Sardar
V. Khedekar
Ryan Luis
Hema Naik
R.L. Chavan
Mahesh Mochemadkar
Chandrakant Shirvoikar
Uday K Javali
Vinod Kumar
Pundalik Gawas
Jai Singh
Manoranjan Singh
Jaya Kumar Seelam
V. Ramaswamy
Pratima Kessarkar - Convener
Food:
P. M. Muraleedharan - Chairman
A. Mahale
R. Madhan - Convener
Sponsorship & Finance:
V. Ramaswamy - Chairman
P. C. Rao
P. S. Rao
V. Sanil Kumar
Jaya Kumar Seelam
C.Prakash Babu
A. S. Unnikrishnan - Convener
Abstracts & Souvenir:
B. Nagender Nath - Chairman
V. Ramaswamy
S. Akrekar
Sujal Bandodkar
Jaya Kumar Seelam - Convener
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OSICON-15
22-24 March 2015
Transport:
R A Sreepada - Chairman
P S Pednekar
Uday Mandrekar
H. Dalvi
Prakash Babu - Convener
Registration:
M.R. Ramesh Kumar - Chairman
P.M. Muraleedharan
D. Ilangovan
Prakash Mehra
Maria Desa
Catherine S. Manohar
Liditha K
Jaya Kumar Seelam - Convener
Accommodation:
Dattesh Desai - Chairman
Rajeev Saraswat
Rajaram Patil
Toraskar - Convener
viii
OSICON-15
22-24 March 2015
LIST OF ABSTRACTS
Paper
No.
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
Title
Page
No.
MODELING THE BIOGEOCHEMICAL CYCLE OF MICROBES ALONG THE COASTAL ZONES by Kiran
Gurung* and Geetha N
2
PHYTOPLANKTON BLOOM EVENTS FROM SEAWIFS DATA ACTIVATED BY MULTIPLE FORCINGS IN
BAY OF BENGAL by R. Roy Chowdhury*, A. Chakraborty
3
APPLICATION OF BAYESIAN INVERSION TO OPTIMIZE THE PHYSICAL AND BIOGEOCHEMICAL
PARAMETERS IN OCEAN BIOGECHEMICAL MODELS by Vinu K. Valsala*, N. Pavan Kumar, S.
Maksyutov, R. Murtugudde
5
RECENT INSIGHT ON BIOGEOCHEMICAL CONSTITUENTS IN THE COCHIN ESTUARINE SYSTEM (CES)
by K.Sriram, Soja Louis, C.H. Sujatha*
6
METAL FRACTIONATION PROFILE OF CORE SEDIMENTS IN THE SPECIFIC ZONES OF COCHIN
ESTUARINE SYSTEM by Nair Manju P and C.H Sujatha*
7
CHLOROPHYLL-A DYNAMICS IN NEAR COASTAL WATERS OF WESTERN BAY OF BENGAL USING IN
SITU AND LONG-TERM SATELLITE DATA by Aneesh A. Lotliker*, Sanjiba Kumar Baliarsingh, K. C.
Sahu, T. Srinivasa Kumar
8
ESTIMATION OF AEROSOL AND NUTRIENT DEPOSITION IN THE COASTAL BAY OF BENGAL OFF
VISAKHAPATNAM by K. Yadav*, V.V.S.S. Sarma, M. Dileep Kumar
10
SPATIAL VARIATIONS IN TROPHIC LEVEL OF PRIMARY CONSUMERS ALONG THE GODAVARI
ESTUARY by J. Mukherjee*, V. V. S. S. Sarma
11
A MODELLING STUDY OF BIOLOGICAL FEEDBACKS ON SEA SURFACE TEMPERATURE by Kunal
Chakraborty*, Arya Paul, Satya Prakash
12
EFFECTS OF MACRONUTRIENTS ON COASTAL DIATOM GROWTH DYNAMICS AT VISAKHAPATNAM,
NW COAST OF BAY OF BENGAL, INDIA: AN EXPERIMENTAL APPROACH by Debasmita
Bandyopadhyaya* and Haimanti Biswas
13
VARIATIONS IN EFFICIENCY OF BIOLOGICAL PUMP IN THE BAY OF BENGAL USING STABLE
ISOTOPIC COMPOSITION OF NITROGEN IN THE SUSPENDED MATTER by C.K. Sherin* and V.V.S.S.
Sarma
14
INTRA-ANNUAL VARIABILITY IN ORGANIC CARBON SINKING FLUXES OFF A TROPICAL MAJOR
RIVER, GODAVARI: SEDIMENT TRAP RESULTS by Sreenu Lenka*, M. S. Krishna and V.V.S.S. Sarma
15
SOURCES AND DISTRIBUTION OF PARTICULATE ORGANIC MATTER IN THE WESTERN COASTAL BAY
OF BENGAL DURING SW MONSOON: INFLUENCE OF RIVER DISCHARGE by M.S. Krishna*, L.
Gawade, S.A. Naidu, V.V.S.S. Sarma, N.P.C. Reddy
16
SENSITIVITY OF COASTAL PHYTOPLANKTON TO VARIABLE COPPER CONCENTRATIONS FROM THE
VISAKHAPATNAM COAST (SW COAST OF BAY OF BENGAL, INDIA) by Haimanti Biswas* and
Debasmita Bandyopadhyay
17
BIO-PHYSICAL COUPLING AND UPPER OCEAN BIOLOGICAL PRODUCTIVITY IN THE NORTHERN
INDIAN OCEAN by S. Prasanna Kumar* and Jayu Narvekar
18
EFFECTS OF ZINC ON COASTAL PHYTOPLANKTON GROWTH AND PRIMARY PRODUCTION UNDER
LOW AND HIGH CO2 LEVELS FROM VISAKHAPATNAM by Aziz Ur Rahman Shaik1*, Debasmita
Bandyopadhyay2 and Haimanti Biswas3
19
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Paper
No.
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
Title
Page
No.
DISTRIBUTION OF BIOCHEMICAL COMPOUNDS IN INDIAN MONSOONAL ESTUARIES DURING SW
MONSOON by B.S.K. Kumar*, V.V.S.S. Sarma, M.S.R. Krishna and N.P.C. Reddy
20
OBSERVED INTRA-SEASONAL VARIABILITY OF CHLOROPHYLL-A USING ARGO PROFILING FLOAT IN
THE EASTERN EQUATORIAL INDIAN OCEAN by V. P. Thangaprakash*, M. S. Girishkumar, T.V.S.
Udaya Bhaskar, M. Ravichandran
21
VARIABILITY OF PHYTOPLANKTON PIGMENT CONCENTRATION IN INDIAN ESTUARIES DURING
PEAK RIVER DISCHARGE PERIOD by D. B. Rao*, V.V.S.S. Sarma, M.S. Krishna and N.P.C. Reddy
22
INTERANNUAL TO LONG-TERM VARIABILITY OF OXYCLINE ALONG THE WEST COAST OF INDIA:
UNDERSTANDING ANOXIC EVENTS THROUGH MODELING APPROACH by V. Parvathi*, I. Suresh, S.
Neetu, M. Lengaigne, M. Levy, L. Resplandy, C. Ethé, J. Vialard, O. Aumont, H. Naik, SWA. Naqvi
23
VERTICAL VARIATION OF PRIMARY PRODUCTIVITY IN PRESENCE OF ULTRAVIOLET RADIATIONS,
CENTRAL WEST COAST OF INDIA by Prachi A. Naik*, M. Gauns
24
INFLUENCE OF ANTHROPOGENIC ACTIVITIES ON ABUNDANCE OF HETEROTROPHIC AND
PATHOGENIC BACTERIA ALONG THE COAST OF ANDAMAN ISLANDS by P. Sudharani*, Y.
Sathibabu, T. N. R. Srinivas
26
BENTHIC REMINERALIZATION AND NUTRIENTS EXCHANGE ALONG THE SALINITY GRADIENT OF A
TROPICAL ESTUARY, CENTRAL WEST COAST OF INDIA by A. K. Pratihary*, J. Araujo, K.F. Bepari, R.
Naik, S. Morajkar, P. Satardekar, D.M. Shenoy, S.W.A. Naqvi
27
BIOGEOCHEMICAL CYCLING IN MANDOVI AND ZUARI ESTUARIES, WEST COAST OF INDIA by Hema
Naik, D. M. Shenoy, S. Kurian, S. W. A. Naqvi
29
VARIATION OF DIMETHYLSULPHIDE AND ASSOCIATED COMPOUNDS IN THE MANDOVI AND ZUARI
ESTUARY by Kausar Fatima M. Bepari, Damodar M. Shenoy*, M. Gauns, H. Naik and S.W.A. Naqvi
31
IMPACT OF SEWAGE DISCHARGE ON THE WATER QUALITY OF VERSOVA CREEK by Anirudh Ram*,
B. R. Thorat, M. A. Rokade, D. Majithiya, A. Yadav, S. Salvi, V. Joshilkar, N. Shinde, Jiyalal Ram. M.
Jaiswar, S. N. Gajbhiye
32
METHANE EMISSIONS FROM THE SHELF WATERS OF SOUTHEASTERN ARABIAN SEA by
V.Sudheesh, G.V.M.Gupta* and M.Sudhakar
34
BEHAVIOUR AND FATE OF TRACE ORGANIC CONTAMINANTS IN THE COCHIN ESTUARINE SYSTEM
(CES), INDIA: AN OVERVIEW by P.S. Akhil, C.H. Sujatha*
35
INTER-SEASONAL OBSERVATIONS IN DMS (P) VARIABILITY IN TROPICAL INTERTIDAL ESTUARINE
ECOSYSTEM by Pandey Sunita Surendra, P. A. LokaBharathi*
36
MEASUREMENT OF NITROGEN FIXATION RATES ALONG THE SOUTHWEST COAST OF INDIA by Ayaz
Ahmed*, Mangesh Gauns, Pratirupa Bardhan, Damodar Shenoy, Hema Naik, Siby Kurian, Anil
Kiran Pratihary and SWA Naqvi.
38
CONCENTRATION OF TRACE METALS AND THEIR COVARIANCE WITH CARBON, NITROGEN AND
SULPHUR IN ANOXIC ENVIRONMENT OF VERAVAL HARBOUR by Divya Majithiya, Ajay Yadav,
Anirudh Ram*, Shailesh Salvi, Archana Kamble
39
PHYTOPLANKTON–ZOOPLANKTON DYNAMICS IN COASTAL WATERS OF CENTRAL WEST COAST OF
INDIA by Mangesh Gauns, Anil Pratihary, D M Shenoy, Siby Kurian, H Naik and S.W.A. Naqvi
41
GLOBAL SEAWATER DMS CLIMATOLOGY: COMPARISON & UPDATE by Smrati Gupta*, Anoop S.
Mahajan
42
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Paper
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201
205
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208
209
210
211
212
213
214
215
216
217
218
219
220
221
Title
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No.
CARBON DIOXIDE EMISSIONS FROM A TROPICAL ESTUARY LOCATED ALONG THE WEST COAST OF
INDIA- ZUARI ESTUARY by Rashith P*, H. Naik, D. M. Shenoy and S.W. A. Naqvi
44
ROLE OF NINGALOO NINO/NINA IN ALTERING THE BIOLOGICAL ACTIVITY IN SOUTHERN SUB
TROPICAL INDIAN OCEAN by Sandeep.N, K. Ashok, Swapna.P*, Aparna.K
47
ROLE OF INDIAN OCEAN SST IN MODULATING ONSET AND PROGRESSION OF ISM IN THE
SUCCESSIVE YEARS OF 2013 AND 2014 by Ramesh Kumar Yadav* and Bhupendra Bahadur Singh
48
OBSERVATIONAL EVIDENCE OF MIXED ROSSBY GRAVITY WAVES AT THE CENTRAL EQUATORIAL
INDIAN OCEAN by P.M. Muraleedharan*, S. Prasanna Kumar, K. Mohanakumar, S. Sijikumar,
K.U.Sivakumar, Teesha Mathew
49
PRECIPITATION EXTREMES DURING SOUTHWEST MONSOON AND ITS CONNECTION WITH INDIAN
OCEAN DIPOLE by J.V. Revadekar*, H. Varikoden
50
TROPICAL INDIAN OCEAN SIMULATION USING NEMO-AGRIF by Umesh Kumar Singh*, Suneet
Dwivedi, Lokesh Kumar Pandey
51
IMAPCT OF INDIAN OCEAN VARIABILTY ON INDIAN SUMMER MONSOON RAINFALL DURING
RECENT YEARS by Sanjo Jose V*, E. K. Kurien, Athira P. Ratnakaran, Binsiya T. K.
52
POSSIBLE ROLE OF INDIAN OCEAN IN THE BIENNIAL TRANSITION OF INDIAN SUMMER MONSOON
IN OBSERVATION AND CMIP5 SIMULATIONS by Prasanth A Pillai*, A. K Sahai
53
ROLE OF INDIAN OCEANS IN CLIMATE OF WEST COAST OF INDIA by P.K. Murumkar, H. Varikoden,
S.A. Ahmed, J.V. Revadekar*
54
NEAR-SURFACE STRATIFICATION AND SUBMESOSCALE FRONTS IN THE NORTH BAY OF BENGAL IN
AUGUST-SEPTEMBER 2014 by J. Sree Lekha*, S. Shiva Prasad, M. Ravichandran, D. Sengupta
55
INFLUENCE OF INDO-PACIFIC SEA SURFACE TEMPERATURE ON THE PRECIPITATION OVER
NORTHWEST HIMALAYAS by V. M. Shakuntala, J. V. Revadekar, S. A. Ahmed and H. Varikoden*
57
CLIMATOLOGICAL VARIATION OF CIRCULATION FEATURES OF THE NORTH INDIAN OCEAN AND ITS
INTERANNUAL VARIABILITY FROM TOPEX/POSIDEN ALTIMETRY by R. Sen*, A. Chakraborty
58
RETRIEVING OF TEMPERATURE AND SALINITY OF THE INTERIOR OCEAN FROM HIGH RESOLUTION
SATELLITE SEA SURFACE TEMPERATURE by D. Sarkar*, A. Chakraborty, Raj Kumar, Rashmi Sharma
60
SUBSURFACE TEMPERATURE BIAS IN THE EQUATORIAL INDIAN OCEAN IN NCEP CLIMATE
FORECASTING SYSTEM by G. Srinivas*, J. S. Chowdary, Rashmi Kakatkar, Anant Parekh and C.
Gnanaseelan
62
A REVIEW OF LATE HOLOCENE CLIMATE CHANGE FROM WESTERN INDIA: HUNTING ARCHIVES FOR
RECONSTRUCTING HIGH RESOLUTION CLIMATE DYNAMICS by Nisarg Makwana*, S.P. Prizomwala,
N.P. Bhatt, B.K. Rastogi
63
NUDGING OF THERMODYNAMIC PROFILES: IMPACT ON REPRESENTATION OF INDIAN SUMMER
MONSOON by Raju Attada, Anant Parekh*, C. Gnanaseelan and J. S. Chowdary
64
INTERCOMPARISON OF NIOT WAVE BUOY DATA WITH DATAWELL WAVERIDER BUOY by J.
Vimala*, K. Ramesh, G. Latha and R. Venkatesan
65
SOIL MOISTURE DURING SOUTHWEST MONSOON PERIOD AND ITS RELATION WITH INDIAN
OCEAN SEA SURFACE TEMPERATURE by H. Varikoden*and J. V. Revadekar,
66
RESPONSE OF BAY OF BENGAL TO CYCLONE PHAILIN FROM MOORED AND SATELLITE DATA by
Chaudhuri. D*, Vekatesan. R, Ravichandran. M, Sengupta. D
67
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INDIAN SUMMER MONSOON AND THE OCEAN HEAT BUDGET SIMULATED IN CFSV2 MODEL by
Gibies George*, D. Nagarjuna Rao, C.T. Sabeerali, A. Suryachandra Rao
69
PREDICTION AND ERROR GROWTH IN THE DAILY FORECAST OF PRECIPITATION FROM THE NCEP
CFSV2 OVER THE SUBDIVISIONS OF INDIAN CONTINENT by Shailendra Rai, *, Dhruva Kumar
Pandey, A. K. Sahai and S. Abhilash
71
MODELING THE HYDROGRAPHY AND CIRCULATION OF THE BAY OF BENGAL USING A HIGHRESOLUTION OCEAN CIRCULATION MODEL by Atul Srivastava*, Suneet Dwivedi and Alok Kumar
Mishra
73
USING THE TELESCOPICALLY VARYING HORIZONTAL AND VERTICAL GRIDS FOR MODELING THE
INDIAN OCEAN VARIABILITY by Anupam Kumar Dixit* and Suneet Dwivedi
74
POSSIBLE INTERACTIONS BETWEEN SUBSURFACE OCEAN BIASES AND THE SURFACE INTERANNUAL
VARIABILITY IN COUPLED MODELS. by Shikha Singh*, Vinu Valsala
75
NORTH-SOUTH HEMISPHERIC THERMAL CONTRAST AND INDIAN SUMMER MONSOON RAINFALL
VARIABILITY by Lekshmi Mudra. B* and H. N. Singh
76
STUDY OF INDONESIAN THROUGHFLOW USING HYBRID COORDINATE OCEAN MODEL by Vivek
Kumar Pandey*, Sudhir Kumar Singh, Satyam Srivastava
77
ROLE OF UPPER OCEAN STRATIFICATION IN THE INTENSIFICATION OF THE SEVERE CYCLONE
“HUDHUD” by K.Maneesha*, Y.Sadhuram and V.S.N.Murty
78
SEASONAL CHANGE IN THE TROPICAL CYCLONE CHARACTERISTICS BETWEEN PRE- AND POSTMONSOON SEASONS IN THE BAY OF BENGAL: RESPECTIVE INFLUENCE OF THE OCEAN AND
ATMOSPHERE by M. Teesha, S. Neetu , M. Lengaigne , J. Vialard , G. Samson
80
REMOTE AND REGIONAL OCEANIC INFLUENCE DURING SOUTH-WEST SUMMER MONSOON 2014.
by Milind Mujumdar*, Swapna P., M. K. Roxy, Sabin T.P., C. Gnanaseelan, and R. Krishnan
81
ON THE POSSIBLE CAUSE OF DISTINCT EL NIÑO TYPES IN THE RECENT DECADES by Jyoti J, Swapna*
P, Shamal Marathe and K. Ashok
82
INTRASEASONAL TO INTERANNUAL VARIABILITY OF SURFACE LAYER TEMPERATURE INVERSION IN
THE BAY OF BENGAL by Pankajakshan Thadathil, I. Suresh, S. Gautham*,S. Prasanna Kumar ,
Matthieu Lengaigne, R.R.Rao, S. Neetu and Y.K. Somayajulu
83
EFFECT OF RIVER DISCHARGE IN SIMULATION OF SEA SURFACE SALINITY USING ROMS MODEL by
K. K. Sandeep*, Vimlesh Pant, A. D. Rao, Arulalan T
84
ROLE OF IOD AND ENSO ON THE INTER-ANNUAL VARIABILITY OF TROPICAL INDIAN OCEAN by Anju
S*, P. Swapna, K.Ashok,, Sandeep and Jyoti
85
RELATIVE ROLE OF EL-NINO SOUTHERN OSCILLATION AND IOD EVENTS ON MONSOON ACTIVITY
OVER INDIA by S. Gopika*, M. R. Ramesh kumar
86
PROCESSES ASSOCIATED WITH THE ARABIAN SEA MINI WARM POOL FORMATION AND THEIR
EPOCHAL CHANGES by Aniket Barphe, ,*, C. Gnanaseelan and P. Pradeep Kumar
87
INDIAN OCEAN WARMING – ITS EXTENT, AND IMPACT ON THE MONSOON AND MARINE
PRODUCTIVITY by Roxy M. K.*, K. Ritika, A. Modi, P. Terray, R. Murtugudde, K. Ashok, B. N.
Goswami, S. Masson, V. Valsala, P. Swapna, S. Prasanna Kumar and M. Ravichandran
88
FLAVOURS IN THE DECAY PHASE OF EL NIÑO AND THE ASSOCIATED RESPONSE ON MONSOON
CIRCULATION AND RAINFALL by H. Sree Harsha*, J. S. Chowdary, C. Gnanaseelan, C.V. Naidu, G.
Srinivas, A Parekh and Prasanth Pillai
89
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SUB-SURFACE TEMPERATURE TRENDS IN THE NORTH INDIAN OCEAN AND OCEAN VERTICAL
PROCESSES by Anand babu Amere, *, Anant Parekh, Fousiya T.S, G.Bharathi, C.Gnanaseelan and
J.S.Chowdary
90
THE STRUCTURE OF INDIAN OCEAN MERIDIONAL OVERTURNING IN OCEAN REANALYSIS DATASETS
AND AN OGCM by S Rahul, C Gnanaseelan
91
MESO-SCALE EDDIES IN THE NORTH INDIAN OCEAN AND THEIR PROPAGATION PATHWAYS by T.N.
Shyni and P.V. Hareesh Kumar
92
PHYSICAL PROCESSES CONTROLLING MIXED LAYER VARIABILITY IN THE NORTHERN INDIAN OCEAN
by Jayu Narvekar* and S. Prasanna Kumar
93
VARIABILITY AND TRENDS IN THE TROPICAL INDIAN OCEAN SEA SURFACE SALINITY, IN A
CHANGING CLIMATE by Vivek Shilimkar *, M. K. Roxy
94
IMPACT OF AQUARIUS SEA SURFACE SALINITY ASSIMILATION IN IMPROVING THE OCEAN STATE by
Vivek .S*, P. Sreenivas, C. Gnanaseelan and K. V. S. R. Prasad
95
DYNAMICAL LINK BETWEEN TROPICAL INDIAN OCEAN AND CYCLONES by P. Sreenivas*, C.
Gnanaseelan, J.S. Chowdary and K.V.S.R. Prasad
96
ASSIMILATION OF ALTIMETRY DERIVED TEMPERATURE AND SALINITY IN GODAS AND ITS IMPACT
ON MONSOON PREDICTION by P. Sreenivas, N. Pavan Kumar, R. Kakatkar and C. Gnanaseelan
97
EQUATORIAL INDIAN OCEAN SUBSURFACE CURRENT VARIABILITY IN AN OCEAN GENERAL
CIRCULATION MODEL AND ITS IMPACT ON REGIONAL CLIMATE. by Aditi Deshpande* and C.
Gnanaseelan
98
INTER-ANNUAL VARIABILITY OF UPPER OCEAN STRATIFICATION IN BAY OF BENGAL:
OBSERVATIONAL AND MODELING ASPECTS by T.S. Fousiya*, Anant Parekh and C. Gnanaseelan
99
A NEW MODE OF VARIABILITY IN THE TROPICAL INDIAN OCEAN SUBSURFACE TEMPERATURE AND
ITS CLIMATIC IMPACTS by C. Gnanaseelan* and Sayantani Ojha
100
INTER COMPARISON OF DIFFERENT OCEAN MODELS OVER THE TROPICAL INDIAN OCEAN by
Ananya Karmakar*, Anant Parekh, Jasti Chowdary, and C. Gnanaseelan
101
IMPACT OF PROLONGED ENSO EVENTS ON TROPICAL INDIAN OCEAN IN THE COUPLED MODEL
CFSV2 AND OBSERVATIONS by P. Singh, J.S. Chowdary and C. Gnanaseelan
102
PHYSICO-CHEMICAL PROPERTIES AND STABLE OXYGEN ISOTOPIC (Δ18O) VARIATIONS OF
SEAWATER, ALONG THE CONTINENTAL SHELF DURING POST NE AND SW MONSOON PERIODS,
SOUTH EAST COAST, INDIA. by Nisha.V* and H. Achyuthan
103
DECADAL VARIABILITY IN THE TROPICAL INDO PACIFIC OCEAN AND ITS IMPACT ON INDIAN
SUMMER MONSOON by Abhishek Savita, *, C. Gnanaseelan, S. Rahul
104
DYNAMICS OF SUMMER MONSOON OCEANIC EDDIES IN BAY OF BENGAL AND ITS EFFECT ON
ATMOSPHERE by Saurabh Rathore*, Anant Parekh, Mihir Kumar Dash
105
VARIABILITY OF ATMOSPHERIC REFRACTIVE INDEX STRUCTURE PARAMETER (CN2) – A CASE
STUDY AND IT’S PREDICTION USING METEOROLOGICAL DATA by G Nageswara Rao* and Amit
Pratap
107
EPOCHAL CHANGES IN THE DOMINANT SUBSURFACE MODE OF TROPICAL INDIAN OCEAN by Ojha
Sayantani* and C. Gnanaseelan
108
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VALIDATION OF GEKCO AND OSCAR PRODUCTS FOR THE INDIAN OCEAN REGION USING IN – SITU
OBSERVATIONS FROM MOORINGS by A Phanindra Reddy*, Simi Mathew, G. Latha and R.
Venkatesan
109
IMPACT OF CLIMATE MODES ON THE INTER-ANNUAL VARIABILITY OF ZONAL CURRENTS IN THE
EQUATORIAL INDIAN OCEAN. by Chinnu Sachidanandan* and P.M. Muraleedharan
110
SPATIO-TEMPORAL VARIATIONS IN SALINITY PROFILES OVER THE BAY OF BENGAL by Kumar Ravi
Prakash*, Vimlesh Pant
111
SUPPLEMENTING XBT OBSERVATIONS WITH SALINITY IN THE BAY OF BENGAL by Venugopal
Reddy.T, Ali.M.M*, Gopala Krishna.V.V
112
GPS/GSM BASED SEAMLESS IN-SITU PROFILER FOR ATMOSPHERIC BOUNDARY LAYER by Femy
Paulose*, Feby Paulose, Gibies George
114
ESTABLISHMENT OF SHIPBOARD AWS ON INDIAN RESEARCH VESSEL SINDHU SADHANA by K. Vijay
Kumar, Prakash Mehra, Yogesh Agarvadekar, Govind Ranade, G.P Naik, Ryan Luis, Bharat
Harmalkar, Devika V. Ghatge, Narayan Satelkar, and Pramath Keny
116
SPATIAL DISTRIBUTION OF SOFAR CHANNEL PARAMETERS OVER BAY OF BENGAL by K.Ashalatha,
T.V.R.Murty, K.V.S.R.Prasad
117
DEVELOPMENT OF MICROBIAL FUEL CELL BASED ENERGY HARVESTING SYSTEM USING MARINE
SEDIMENT FOR UNDERWATER APPLICATIONS by P. Janani*, S. Sakthivel Murugan, N. Archana
118
RAIN FALL ANALYSIS USING NOISE MEASUREMENTS IN SHALLOW WATERS OFF ANDHRA COAST by
M. Ashokan*, G. Latha, K. Nithyanandam
119
CONVERTED WAVE AVO ANALYSIS FOR RESERVOIR CHARACTERISATION by Prabhakar Nayak, A. K.
Rai
120
DEVELOPMENT OF DUAL MODE COMMUNICATION A NOVEL TECHNIQUE FOR REAL TIME
TSUNAMI BUOY SYSTEMS by R.Sundar, M.Arulmuthiah, S.Elango, D.Gowtham, R.Venkatesan,
M.A.Atmanand
121
AMBIENT NOISE VARIABILITY ALONG THE CENTRAL WEST COAST OF INDIA – OFF GOA by R.
Kannan*, G. Latha, G. Raguraman
122
FISH CHORUS RECORDED IN THE SOUTHEASTERN ARABIAN SEA: A COMPARISON STUDY WITH
OTHER SHALLOW WATER ENVIRONMENTS by M. M. Mahanty*, G. Latha and A.Thirunavukkarasu
123
NOISE LEVEL VARIABILITY AND SPECTRAL CHARACTERISTICS OF SHALLOW WATER AMBIENT NOISE
AT VIZAG by K.K Noufal*, M.C Sanjana, G. Latha
124
HINDUSTAN UNIVERSITY AUTONOMOUS UNDERWATER VEHICLE: DESIGN AND IMPLEMENTATION
OF THE POSEIDON AUV by S.Suryakumar*, Gokulavasan, Indrajeet Ghosh, A.Muthuvel, N.Prakash,
K.Kamalakkannan
125
MAPPING SLOPE MORPHOLOGY OFF GOA, WESTERN CONTINENTAL MARGINS OF INDIA by
Andrew Menezes*, S. M. Karisiddaiah, Bishwajit Chakraborty, K. Haris, William Fernandes
127
A METHOD FOR IMPROVING MULTIBEAM BATHYMETRY DATA QUALITY AFFECTED BY ERRONEOUS
SOUND SPEED by William A. Fernandes*, Bishwajit Chakraborty
128
RECENT ADVANCES IN THE DESIGN OF SONAR HUMAN MACHINE INTERFACE by *Anjaly C Gopi, G
K Nagarajan, Sumi A Samad and V S Shenoi
130
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REFINEMENT OF SHALLOW WATER DEPTH ESTIMATION ALGORITHM USING WEIGHTED LINEAR
REGRESSION APROACH by Vinayaraj Poliyapram, Venkatesh Raghavan, Glejin Johnson and V.V.
Sanil Kumar
131
A VLSI BASED INTEGRATED DATA ACQUISITION SYSTEM FOR POLAR OBSERVATORY by Lydia Kiruba
R*, M.Arul Muthiah, R. Venkatesan, A. Sivagami
133
COLLECTION OF OCEANOGRAPHIC DATA IN MACRO TIDAL REGIME- GULF OF KHAMBHAT
EXPERIENCE. by M.Sankar, K.M.Sivakholundu, B.K.Jena, Vijaya Ravichandran, V.Suseentharan,
Karunakar Kintada
134
DEVELOPMENT OF DRIFTER BUOY FOR MEASURING CURRENTS IN SURF ZONE by V
Suseentharan*, K M Sivakholundu, Basanta Kumar Jena, M Ravinder, R Balaji
135
HIGH STRENGTH TERMINATION TECHNIQUE FOR VECTRAN FIBRE ARMOURED UNDERWATER TOW
CABLES by Kiran Govind V*, Anshath Hussain, Thulasidas K R, Sabu Sebastian M
136
INTER-COMPARISON OF COLLOCATED CUP TYPE AND SONIC ANEMOMETER ON THE MOORED
COASTAL BUOY by Jagadeesh Kadiyam, G. Vengatesan, M Arul Muthiah, J. Vimala and Dr. R
Venkatesan
138
A REVIEW ON THE INDIRECT ESTIMATION OF GEO-ACOUSTIC PROPERTIES OF SEABED by V.K.
Unny*, C.P. Uthaman, Nitheesh Thomas
139
COOPERATIVE MOTION CONTROL OF MULTIPLE AUVS – CHALLENGES IN IMPLEMENTATION by
Manish Singh*, Nupur Thakker, Pramod Maurya, Gajanan Navelkar, Antonio Mascarenhas
140
VALIDATION OF INDIAN TSUNAMETER IN LABORATORY ENVIRONMENT by Tata Sudhakar* and
G.A. Ramadass
141
UNDERSTANDING EARTHQUAKES AND TSUNAMI HAZARD IN BAY OF BENGAL by Saroj K. Dash, A.
K. Rai*
144
ROLE OF MARINE TRANSGRESSION IN THE FORMATION OF KACHCHH BAUXITE, GUJARAT, INDIA
by P.S.Choudhury, G.N.Jadhav and D.U.Vyas
145
EVALUATION OF NUMERICAL MODELS FOR PALAEOTSUNAMI/PALAEOSTORM DEPOSITS FROM
SAURASHTRA COAST, WESTERN INDIA by Drasti Gandhi, *, S.P.Prizomwala, N.Y.Bhatt, Kapil
Mohan, B.K. Rastogi
146
DEMARCATION OF NEAR SUBBOTTOM SEDIMENT STRATA OF SHALLOW WATERS USING IMAGE
PROCESSING by Satyanarayana Yegireddi
147
DISTRIBUTION OF REE IN SEDIMENT CORES FROM THE THANE CREEK, MUMBAI by Lina L.
Fernandes *, Pratima M. Kessarkar, V. Purnachandra Rao
149
GEOCHEMISTRY OF THE SURFACE SEDIMENTS WITHIN AND BELOW OXYGEN MINIMUM ZONE
FROM THE SOUTHWESTERN CONTINENTAL MARGIN OF INDIA by Pratima M. Kessarkar*, G.
Parthiban, J.N. Pattan, Lina L. Fernandes, Supriya G. Karapurkar, Siby Kurian, V. Purnachandra
Rao
150
DELIVERY OF PARTICULATE ORGANIC CARBON DURING THE GREAT FLOOD OF KRISHNA RIVER IN
OCTOBER 2009 by C. Prakash Babu*, V. Ramaswamy, P.S. Rao
151
MINERALOGY AND RARE EARTH ELEMENTS IN SEDIMENT CORES FROM THE MANDOVI ESTUARY,
WESTERN INDIA: INFERENCES ON SOURCES OF THE SEDIMENTS by Prajith, A., Rao, V. P.* and
Pratima M. Kessarkar
152
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No.
STABLE ISOTOPIC INVESTIGATION OF PORITES CORAL FROM MINICOY ISLAND by A. A. Fousiya, S.
Chakraborty*, H. Achyuthan, Naveen Gandhi, Nitesh Sinha, Amey Datye
153
ANTHROPOGENIC IMPRINTS ON A SEDIMENT CORE OFF GOA FROM THE ARABIAN SEA – A ROCK
MAGNETIC & GEOCHEMICAL APPROACH by Tyson Sebastian*, Sangeeta Naik, B.Nagender Nath,
D.V.Borole
155
WET DEPOSITION OF MIDDLE-EAST DUST OVER THE INDIAN PENINSULA by V. Ramaswamy*,
Prakash Babu
156
PRELIMINARY OBSERVATIONS OF GEOMORPHOLOGICAL, SEDIMENTOLOGICAL AND
MINERALOGICAL CHARACTERISTICS OF THE ARNALA BEACH AND ARNALAPADA ISLAND, THANE
DISTRICT, MAHARASHTRA, INDIA by S. D. Iyer, A. R. Gujar, D. K. Naik, S. S. Gaonkar, R. A. A. Luis, F.
K. Badesab
157
PARTITIONING OF METALS IN DIFFERENT BINDING PHASES OF MARINE SEDIMENTS: IMPORTANCE
OF METAL CHEMISTRY by P. Chakraborty
159
ISOTOPIC FINGERPRINTING OF ATMOSPHERIC DUST OVER ARABIAN SEA by A. Kumar*, K. Suresh,
P. P. Padalkar, C. Prakashbabu, V. Ramaswamy
160
DISTRIBUTION AND SPECIATION OF PB IN COASTAL SEDIMENTS AROUND INDIA by Sucharita
Chakraborty*, Parthasarathi Chakraborty and B. Nagender Nath
162
HIGH RESOLURION HOLOCENE PALEOMAGNETIC SECULAR VARIATION RECORDS FROM BAY OF
BENGAL by A. Usapkar, P. Dewangan*, F.K. Badesab, A. Mazumdar, T. Ramprasad, K.S. Krishna, N.
Basavaiah
163
INITIATION OF OCEAN BOTTOM SEISMOMETER EXPERIMENT IN THE ANDAMAN BACK ARC BASIN
by K.A. Kamesh Raju*, Pawan Dewangan, Aswini, K.K., Yatheesh, V., Pabitra Singha, Kiranmayi S
164
SULFUR AND IRON SYSTEMATICS OF A CORE (MD161-15) FROM THE KRISHNA-GODAVARI BASIN,
BAY OF BENGAL by M. Carvalho, A. Mazumdar*
165
INFLUENCE OF LAND USE PATTERN ON DISTRIBUTION OF ORGANIC MATTER IN A TROPICAL
LAGOON by Arindam Sarkar*, B.Nagender Nath
166
NATURE OF SULFIDIZATION WITHIN A SEDIMENT COLUMN OFF MAHANADI BASIN, BAY OF
BENGAL, INDIA by Brahmanand Sawant, A. Mazumdar*, Maqbool Yousuf, Aditya Peketi
167
DEPOSITIONAL ENVIRONMENT OF THE SURFACE SEDIMENTS IN CENTRAL INDIAN BASIN (CIB),
INDIAN OCEAN BASED ON THEIR MAJOR ELEMENT COMPOSITION by Simontini Sensarma, Ranadip
Banerjee* and Subir Mukhopadhyay
168
TERRESTRIAL AND MARINE PRODUCTIVITY: SOME COMMON THREADS by R. DaSilva, A.
Mazumdar*, R.K. Joshi, A. Shaji, P. Mahalakshmi, B.G. Naik
169
THE EFFECT OF HOLOCENE TEMPERATURE CHANGES ON HUMAN SETTLEMENTS IN ASIA by Rajeev
Saraswat
170
SEDIMENT DISPERSAL AND TRANSPORT ON THE CONTINENTAL SHELF OF MYANMAR, NORTHEAST
INDIAN OCEAN by P.S. Rao and V.Ramaswamy
171
IDENTIFICATION OF SOURCES AND FREQUENCY OF MINERAL DUST OVER THE MIDDLE-EAST AND
SOUTHWEST ASIA BY USING SATELLITE DATA. by K.Suresh*, V.Ramaswamy, C.Prakashbabu
173
PHOSPHATE UPTAKE BY MICROBIAL COMMUNITES IN THE CONTINENTAL MARGIN SEDIMENTS by
S. S. Mamatha*, P.P.Sujith, S. Benjamin, D. Vaigankar, T. Singh, T.R.A. Thomas, B. Nagender Nath,
P.A. Loka Bharathi
174
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519
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No.
SURFZONE CURRENTS AT MIRAMAR BEACH OF GOA, INDIA: A COMPARISON OF OBSERVATION
AND THEORY by Yadhunath E.M, Jaya Kumar Seelam*, Jishad, M, Gowthaman R, Pednekar P.S
178
CHANGE DETECTION STUDIES ALONG VENGURLA COAST, INDIA THROUGH REMOTE SENSING AND
GIS by R. Gowthaman*, Y.G. Harikrishna Sharma and V. Sanilkumar
180
UPWELLING FEATURES OFF SOMALIA AND OMAN COASTS FROM MODEL SIMULATIONS by Tanuja
Nigam*, Vimlesh Pant
182
EVALUATION OF MITIGATION OPTIONS FOR SUSTAINABLE SHORELINE MANAGEMENT FOR
POOMPUHAR COAST by Abhishek Tavva*, S Sankar, Vijaya Ravichandran, KM Sivakholundu
183
EFFECT OF WIND DRIVEN CIRCULATION ON INTERNAL WAVES: A CASE STUDY by Sachiko
Mohanty*, Himansu K Pradhan, A D Rao
184
VALIDATION OF STORM SURGES USING A COUPLED SURGE-TIDE-WAVE MODEL: A CASE STUDY
FOR TAMIL NADU COAST by Smita Pandey*, Jismy Poulse , A D Rao
185
EVIDENCES OF HIGH ENERGY MARINE EVENTS FROM THE GUJARAT COAST, WESTERN INDIA:
STORM OR TSUNAMI DEPOSITS? by S.P.Prizomwala*, Drasti Gandhi, , N.P. Bhatt, B.K. Rastogi
186
PERFORMANCE OF DELFT3D-WAVE MODULE IN THE NEAR-SHORE WAVE TRANSFORMATION OFF
RATNAGIRI, WEST COAST OF INDIA by Glejin Johnson and V. Sanil Kumar*
187
MODELLING THE BIOLOGICAL ACTIVE LAYER CIRCULATION IN THE SOUTH-EASTERN ARABIAN SEA
by Vijay Kumar
188
TIDAL INLET CLASSIFICATION ALONG THE COASTS OF GOA AND KARNATAKA by M. Vikas, Jaya
Kumar Seelam*, Subbarao
189
A STUDY ON SEASONAL MORPHOLOGICAL CHANGES AND CLASSIFICATION OF TIDAL INLETS
ALONG GUJARAT AND KERALA COASTS by N. Amarnath Reddy*, M. Vikas, Jaya Kumar Seelam,
Subbarao
191
MORPHOLOGICAL CHANGES DUE TO DEVELOPMENTAL ACTIVITIES AT PARADIP PORT by S.G.
Manjunatha*, K.B. Bobade, M.D. Kudale
193
PREDICTION OF SHORELINE DYNAMICS USING GEOSPATIAL TECHNOLOGY: A CASE STUDY OF
ENNORE COAST, TAMIL NADU, INDIA by S. Saravanan*, R. Manjula, S. Sivaranjani
195
TIDE MODULATION OF SURFZONE WAVES OFF MAHARASHTRA COAST ON THE CENTRAL WEST
COAST OF INDIA by M. Jishad*, Jaya Kumar Seelam
196
SPRING-NEAP VARIABILITY IN RESIDUAL FLUXES THROUGH COCHIN INLET by Vinita J*,
Revichandran C., Muraleedharan K.R., Lallu K.R., Jineesh V.K.
197
VARIABILITY OF SUSPENDED SEDIMENT CONCENTRATION AND ITS TIDAL INFLUENCE IN THE GULF
OF KACHCHH, INDIA by R. Ratheesh*, A.S. Rajawat, R. Smitha
199
AN EVALUATION OF FACTORS CONTROLLING DECADAL-SCALE SEA LEVEL RISE IN THE MACROTIDAL GULF OF KACHCHH by Onkar S. Chauhan
202
PRELIMINARY RESULTS OF RADIANT HEATING RATE OF THE COASTAL AND ESTUARINE WATERS OF
GOA by Priya Rauth*, T Suresh, Prakash Chauhan, Arvind Sahay
203
NEARSHORE CURRENTS OF AN UPWELLING REGION, SOUTHWEST COAST OF INDIA by V.K.
Jineesh*, C. Revichandran, K.R. Muraleedharan, K.R. Naveen Kumar
205
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PRELIMINARY OBSERVATIONS ON OCCURRENCE, SPATIAL DISTRIBUTION AND IDENTIFICATION OF
PLASTIC RESIN PELLETS IN SEDIMENTS AROUND AGATTI ISLAND, LAKSHADWEEP ARCHIPELAGO by
S. Veerasingam*, M. Mugilarasan, R. Venkatachalapathy, P. Vethamony
207
SEDIMENT TRANSPORT DURING NILAM CYCLONE AT KADALUR PERIYAKUPPAM COAST, TAMIL
NADU by A. S. Kiran*, B. K. Jena and K.M. Sivakholundu
208
OPTIMIZATION OF ENTRANCE CHANNEL IN A TIDAL INLET FOR FISH LANDING JETTY by
L.R.Ranganath*, A.K.Singh, M.Karthikeyan and M.D.Kudale
209
ROLE OF CURRENTS ON THE INTRUSION OF THE BAY OF BENGAL WATER MASS TO
SOUTHEASTERN ARABIAN SEA by Rajith, K., Rao, A. R. and Anil Kumar, K.
210
CHANGING DEPOSITIONAL ENVIRONMENT ALONG NORTH MAHARASHTRA COAST: REASONS AND
POSSIBLE IMPLICATIONS by Volvoikar S. P*, Nayak G. N, Mazumdar A, Peketi A
211
DISTRIBUTION OF SUSPENDED PARTICULATE MATTER IN THE MANDOVI AND ZUARI ESTUARIES:
INFERENCES ON THE ESTUARINE TURBIDITY MAXIMA by Suja S , Pratima M. Kessarkar*, R. Shynu,
V. Purnachandra Rao
212
IMPACT OF THE VERY SEVERE CYCLONIC STORMS – THE PHAILIN AND HUDHUD – ON THE BEACH
PROCESSES ALONG THE VISAKHAPATNAM COAST by Hani, T.*, Ganesan, P. and Murty, V.S.N.
213
SEASONAL AND INTER-ANNUAL VARIABILITY OF COASTAL CURRENTS AND CIRCULATION OFF
VISAKHAPATNAM DURING 2010-2014 by V.S.N.Murty, D.Gayatri Vani*, Y.Steeven Paul,
V.Fernando, T.A.Prakash, Almeida Anselmo and A.Suryanarayana
214
ROLE OF LITHOLOGY AND STRUCTURE ON THE COASTAL LANDFORMS OF GOA, INDIA by G. Q.
Fernandes*, S. D. Iyer, K. Mahender
215
INTERNAL TIDES ON THE CONTINENTAL SHELF AND SLOPE OFF THE EAST COAST OF INDIA by A.K.
Jithin*, A.S. Unnikrishnan, Fernando Vijayan, M.P. Subeesh, R. Fernandes, S. Khalap, S. Narayan, Y.
Agarvadekar, M. Gaonkar, P. Tari, A. Kankonkar, S. Vernekar
217
NEARSHORE PROCESSES AND LITTORAL SEDIMENT TRANSPORT AT AN OPEN BEACH ALONG THE
NORTH TAMIL NADU COAST by D. Sathish Kumar, Basanta Kumar Jena*, Usha Natesan and
K.M.Sivakholundu
218
HYDRODYNAMIC AND WATER QUALITY SIMULATION OF SEWAGE DISCHARGES IN WEST COAST,
MUMBAI: PRESENT AND FUTURE SCENARIO by Trupti Mardikar, Ritesh Vijay* and Satish R. Wate
219
IDENTIFICATION OF INLET AND OUTLET FOR COOL SEAWATER DISCHARGE FROM AN LNG
FACILITY: A SIMULATION APPROACH by Vikash K. Kushwaha, Ankit Gupta, Ritesh Vijay* and Satish
R. Wate
220
VARIABILITY OF INTERNAL TIDES ON THE CONTINENTAL SLOPE OFF JAIGARH, WEST COAST OF
INDIA by M.P Subeesh*, A.S Unnikrishnan
221
A CASE STUDY OF SST DISTRIBUTION OVER BAY OF BENGAL DURING HUDHUD CYCLONE by
T.S.D.Bhavani*, G.Bharathi, P.Amarendra and P. Hariprasad
222
THE ROLE OF WAVE CLIMATE ON COASTAL SEDIMENTATION - A CASE STUDY by R. Anjali, K.Jossia
Joseph*, B. K. Jena, K.M. Sivakholundu and Ravibabu Mandla
223
IMPACT OF CYCLONE ON THE COASTAL AREA THROUGH EMPIRICAL RELATIONS AND NUMERICAL
MODEL by P. Vyshnavi, B. K. Jena*, K. Jossia Joseph, J. Rajkumar and Ravibabu Mandla
224
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AN OBSERVATIONAL STUDY ON WAVE CHARACTERISTICS DURING HUDHUD CYCLONE OFF
GANGAVARAM by P. Amarendra*, K.Gopala Reddy, G. Bharathi, P. Bhanumurthy and T.M.
Balakrishnan Nair
225
TIDAL STREAM ENERGY POTENTIAL AT MANDOVI AND ZUARI RIVERS, GOA by Jaya Kumar Seelam,
Manasa Ranjan Behera, R. Mani Murali, Aqleema Shah, D. Ilangovan, P. Mehra, R. Madhan
226
OBSERVED TEMPORAL AND SPATIAL VARIATION OF STRATIFICATION IN THE ZUARI ESTUARY,
WEST COAST OF INDIA by D. Sundar, A.S. Unnikrishnan, G.S. Michael, A. Kankonkar
228
EFFECT OF CLIMATE CHANGE ON ESTIMATION OF DESIGN WAVE HEIGHT by V. R. Remsiya and
Manasa Ranjan Behera
229
CHANGES IN SEA LEVEL EXTREMES ALONG THE EAST COAST OF INDIA AND AT THE HEAD OF THE
BAY OF BENGAL by A.S. Unnikrishnan, Charls Antony and Philip L. Woodworth
231
UNDERSTANDING SEASONAL CHANGES OF GOA BEACHES USING EMPIRICAL ORTHOGONAL
FUNCTION METHOD by Yadhunath E.M* and Jaya Kumar Seelam
232
TIDAL CURRENT ENERGY ASSESSMENT IN THE GULF OF KHAMBHAT by Aqleema Shah and Manasa
Ranjan Behera
233
PRELIMINARY RESULTS OF UNDERWATER VERTICAL AND HORIZONTAL VISIBILITY OF THE COASTAL
WATERS OF GOA by Shreya S. Joshi*, T Suresh, Anil Kumar
235
BIODIVERSITY AND STATUS OF CORAL REEF IN MALVAN MARINE SANCTUARY, CENTRAL WEST
COAST OF INDIA by Kalyan De , Sambhaji Mote, Lobsang Tsering, Perisamy, R., Vishal Patil, Rahul
Nagesh , Afreen Hussain, Sabyasachi Sautya, Baban Ingole*
239
BENTHIC FLAGELLATE COMMUNITY DISTRIBUTION IN RELATION TO ABIOTIC AND BIOTIC
VARIABLES ALONG THE NORTH EAST COAST OF INDIA, BAY OF BENGAL by Sangeeta Mishra*,
Rakhesh Madhusoodhanan,, Kalavati Chaganti, Raman V Akkur
240
MACROBENTHIC COMMUNITY STRUCTURE IN RELATION TO STRESSORS IN A FISHING HARBOR OF
PARADIP, ODISHA, EAST COAST OF INDIA by Dipti Raut*, Himadri Tanaya Panda, Aswini Nayak,
Biswaprajna Mohanty, Lipika Patnaik
242
STUDY OF CESTODE INFECTION IN SCOLIODON IN MUMBAI REGION, INDIA by V. V. Andhare*, P.
Hatkar and S. Soni
243
STRESS RESPONSE TO VARIATIONS IN TEMPERATURE IN FRESHWATER FOOD FISH
PANGASIANODON HYPOPHTHALMUS by S. Soni* and V. V Andhare
245
STUDY OF BENTHIC FAUNA IN THE NEAR SHORE WATERS OFF GULF OF KUTCH, NORTH WEST
COAST OF INDIA. by Shivanagouda .N. Sanagoudra*, U. G. Bhat
247
SPATIAL AND TEMPORAL VARIATIONS OF COLORED DISSOLVED ORGANIC MATTER IN THE
ESTUARINE AND COASTAL WATERS OF GOA. by Albertina Dias*, T. Suresh, Manguesh Gauns,
Arvind Sahay, Prakash Chauhan
248
STUDY OF EPIPHYTIC DIATOMS ON SEAWEEDS AND ASSESSING THEIR POTENTIAL AS POLLUTION
INDICATORS by V. A. Kulkarni*, S. P. Jagdale
250
SPATIAL AND TEMPORAL COMMUNITY CHARACTERISTICS OF ASSOCIATED ORGANISMS IN
SARGASSUM CINCTUM by Wasim Ezaz*, Temjensangba Imchen
252
ARABIAN SEA LONG TERM PRODUCTIVITY TREND by Prince Prakash* and Satya Prakash
253
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ASSESSING THE ECOLOGICAL STATUS OF COASTAL WATERS OF INDIA USING AMBI (AZTI’S MARINE
BIOTIC INDEX). by SK Sivadas*, R. Nagesh, B.S. Ingole, GVM Gupta
255
DIVERSITY OF MACROBENTHOS AND MACROPHYTE RELATIONSHIP ON THE ROCKY SHORE by Uday
Gaonkar, Periasamy R., S.K. Sivadas, Vishal Patil, B.S. Ingole*
257
EFFECT OF UPWELLING-DRIVEN HYPOXIA ON MACROBENTHIC COMMUNITY OF SOUTH WEST
COAST OF INDIA by Sanitha K. Sivadas*, G.V.M. Gupta, BS Ingole
258
MARINE MICROALGA TETRASPORA SP: ABUNDANCE, NUTRIENT AVAILABILITY AND INDICATION
OF INTRACELLULAR LIPID AT VERAVAL FISHING HARBOUR, GUJARAT, INDIA by A. B. Fulke*, M.
Dey, A. Ram, R. Hardikar and S.N. Gajbhiye
259
ARE BORING SPONGES AN INCREASING THREAT FOR CORAL GROWTH IN MALVAN MARINE
SANCTUARY? by Sambhaji Mote, Kalyan De, Vishal Patil, Perisamy R, Rahul Nagesh, Sabyasachi
Sautya, Baban S. Ingole*
261
QUANTIFICATION OF PHYTOPLANKTON PHOTO-PHYSIOLOGICAL STATUS IN A MONSOONAL
ESTUARY by J. S. Patil*, A. C. Anil
262
SPATIO-TEMPORAL VARIATION IN ASSOCIATED FAUNA OF THE SPONGE CINACHYRELLA
CAVERNOSA by A. Singh, D.V. Desai, N. L. Thakur*
263
RESPONSES OF PICOPHYTOPLANKTON COMMUNITY TO ENVIRONMENTAL CONDITIONS IN
DIFFERENT ECOSYSTEMS by S. Mitbavkar*, A. C. Anil
265
DISTRIBUTION OF CYST PRODUCING DINOFLAGELLATES FROM A MONSOON INFLUENCED
TROPICAL EUTROPHICATED ENVIRONMENT by R. V. Rodrigues*, J. S. Patil, K. Sathish, A. C. Anil
266
BIODIVERSITY PATTERNS OF MEIOBENTHOS FROM THE INDIAN OCEAN by IVY PEREIRA, B. S.
INGOLE*
267
BACTERIOLOGICAL STUDY OF A COMMERCIAL AQUACULTURE POND OF LITOPENAEUS VANNAMEI
ALONG SOUTH WEST COAST, INDIA. by Elaine A. Sabu*, Maria Judith Gonsalves, Sreepada A. R,
Naseera K., Archana Naik and Ramaiah N.
268
PICOPHYTOPLANKTON CONTRIBUTION TO THE PHYTOPLANKTON BIOMASS IN A MONSOON
INFLUENCED TROPICAL ESTUARY by K. M. Rajaneesh*, S. Mitbavkar, A. C. Anil
269
SALINITY INDUCED PHYTOPLANKTON DOMINANCE ALONG TAPI ESTUARINE ECO- SYSTEM by
Prince Prakash Jeba Kumar. J* , Ragumaran.S, Sundararajan.S, Karupasamy.M,
270
DIVERSITY AND COMMUNITY STRUCTURE OF MACROBENTHOS ALONG THE SALINITY GRADIENT
OF AN ANTHROPOGENICALLY STRESSED ESTUARY by J.T. Mulik, S. Sukumaran*, T.V. Vijapure, S.M.
Salvi
271
MACROBENTHIC ASSEMBLAGES OF TWO MARINE PROTECTED AREAS ALONG NORTHWEST COAST
OF INDIA: DIVERSITY AND DISTRIBUTION by T.V. Vijapure, S. Sukumaran*, J.T. Mulik, V.R. Joshilkar,
S. N. Gajbhiye
273
STUDY OF MACROBENTHIC ASSEMBLAGES ON SUBTIDAL NEARSHORE WATERS IN THE VICINITY OF
ADANI POWER LTD MUNDRA, GUJARAT, INDIA by Santosh Kumar Singh, Anil Soni and
Shivanagouda N. Sanagoudra*
275
SPATIAL VARIATION OF PHYTOPLANKTON PIGMENTS ALONG THE EASTERN ARABIAN SEA DURING
THE ONSET OF SOUTH WEST MONSOON by Ayaz Ahmed*, Chandrasekhara Rao, Siby Kurian,
Manguesh Gauns, Amara BM, Bhagyashri N, Hema Naik and S.W.A Naqvi
276
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SEASONAL INFLUENCE ON METHANOTROPHIC ABUNDANCE, ITS ACTIVITY AND METHANE
PRODUCTION IN A TROPICAL MANGROVE ECOSYSTEM by Delcy R. Nazareth*, M-Judith Gonsalves
277
TEMPORAL AND SPATIAL VARIATION IN THE ZOOPLANKTON DISTRIBUTION AND ABUNDANCE IN
THE ZUARI ESTUARY, WEST COAST OF INDIA by Dattesh V Desai*, Dayakaran P, Monteiro MC, Anil,
A.C.
278
VARIATION IN THE CULTURABLE VIBRIO CHOLERAE ABUNDANCE ALONG THE COAST OF INDIA by
Lidita Khandeparker*, Gardade L, Kuchi N, Eswaran R, Hede N, Mapari, K.E., Anil, A.C.
279
DISTRIBUTION AND ABUNDANCE OF MACROBENTHOS FROM MANGALORE PORT by Dattesh V
Desai*, Atchuthan P, Noyel V, Anil, A.C.
280
RESPONSE OF VIBRIO SPP. TO VARIATIONS IN SALINITY AND TEMPERATURE: ELUCIDATION
THROUGH PROTEIN PROFILING by Lidita Khandeparker*, Barnes N, Anil, A.C.
281
MOLECULAR DIVERSITY OF CHROMOPHYTIC PHYTOPLANKTON ASSEMBLAGES FROM
SUNDARBANS MANGROVE ECOREGION BASED ON RBCL GENE SEQUENCING by Brajogopal
Samanta and Punyasloke Bhadury*
282
INFLUENCE OF UPWELLING ON THE DISTRIBUTION OF BACTERIA AND ARCHAEA IN PERSISTENT
MUDBANK REGIONS OF ALLEPPEY, SOUTHWEST COAST OF INDIA by Appukuttan V. Sheeba,
Saumya Nair, Diana Mathew, Gireesh TR, Abdulaziz Anas*
283
RESPONSE OF PHYTOPLANKTON COMMUNITY TO MONSOON INDUCED HYDROLOGICAL
VARIATIONS IN THE ALLEPPEY MUDBANK REGION, SOUTHWEST COAST OF INDIA by Madhu.N.V*,
Ullas. N, Ashwini.R, Jyothibabu. R, Muraleedharan. K.R, Balachandran. K. K
285
SULFUR OXIDIZING POTENTIAL IN THE MANGROVE CLAM POLYMESODA EROSA by T.R.A. Thomas,
P. A. Lokabharathi*
286
MULTIPLE ANTIBIOTIC RESISTANCES AMONG VIBRIO CHOLERA ISOLATED FROM COCHIN ESTUARY,
SOUTHWEST COAST OF INDIA by Vijitha Vijayan, Abdulaziz Anas*, Sneha K.G , Anila Chandran,
Jasmin C, Shanta Nair
288
DYNAMICS AND DISTRIBUTION OF BACTERIA AND VIRUS IN KRISHNA GODAVARI BASIN, BAY OF
BENGAL by Aswathy Vijaya Krishna, Anwesha Sarkar, Jasna Vijayan and Parvathi A*
290
MULTIPLE ANTIBIOTIC RESISTANT VIBRIO HARVEYI ISOLATED FROM PENAEUS MONODON LARVAL
REARING SYSTEMS OF SOUTH INDIA by Somnath S. Pai, R. Preetha,, N.S. Jayaprakash ,, A. Anas,,
I.S. Bright Singh*
291
ADENOSINE TRIPHOSPHATE IN THE WATERS OF WEST COAST OF INDIA-AN INDICATOR OF LIVING
MICROBIAL BIOMASS by Anindita Das, Christabelle EGF-C, Sheryl OF, Sunita Pandey Dhillan Vellip
and LokaBharathi PA*
292
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ABSTRACTS
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OCEAN BIOGEOCHEMISTRY
SESSION - 01
1
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SESSION-01
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22-24 March 2015
MODELING THE BIOGEOCHEMICAL CYCLE OF MICROBES ALONG THE COASTAL
ZONES
Kiran Gurung* and Geetha N
Dept. of Studies in Biotechnology, University of Mysore, Mysore 570006; [email protected]
Microbial communities play a pivotal role in biogeochemical cycling of nutrients.
Microorganisms along the coastal zones have taken part in nutrient cycles too. Due to
global warming there has been a change in the distribution of species of microbes. But
there might have been a possibility too, that microbes may have adapted to the change in
atmospheric warming by altering their metabolic pathways. So the change in a particular
flora may have an effect on another microbial group and so on. Creating an artificial
environment for studying the community structure and ecology will not yield the desired
results in comparison to when studied in the natural environment. We may say that the
construction of the whole community in the coastal zone is in itself a complex task. Our
approach is to analyze each and every aspect by studying these components and the effect
one has on the other. This also includes studying the cycling of nutrients especially nitrogen,
then trying to construct the whole community structure on the basis of obtained
observations. Successful completion of biogeochemical modelling will further make it
possible to determine the rate in change of species distribution along this zone.
2
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PHYTOPLANKTON BLOOM EVENTS FROM SEAWIFS DATA ACTIVATED BY
MULTIPLE FORCINGS IN BAY OF BENGAL
R. Roy Chowdhury*, A. Chakraborty
1
Centre for Oceans, Rivers, Atmosphere and Land Sciences, Indian Institute of Technology Kharagpur;
[email protected]
Ocean colour is a key parameter for understanding oceanic, biological and physical
processes. It is known that the biological processes in the ocean are largely controlled by
the presence of phytoplankton, which are the primary producers and responsible for CO2
fixation in the ocean. The Bay of Bengal is located in the eastern part of the Northern Indian
Ocean due to monsoonal variation, large amount of river discharge, mixing of high-saline
water from its western counterpart and the circulation pattern makes the bay significant
and less productive than its western counterpart. Coastal upwelling and Ekman pumping
have significant role in nutrient abundance in the bay and are responsible for increasing the
phytoplankton biomass. Oceanic and atmospheric differences sufficiently alter the
circulation patterns and thermal structure of the region to produce variability in
phytoplankton biomass. Near real-time data from seawifs was used to detect phytoplankton
bloom in Bay of Bengal from 1998 January to December 2010. Three phytoplankton bloom
events were shown in January, 1998; December, 2000 and December, 2005 in south-eastern
part of the Bay. The bloom was possibly analysed by sea surface temperature, wind stress,
sea surface height and geostrophic current data. It was found that strong cyclonic eddies
transported cold nutrient rich water from subsurface layer to the surface layer which was
responsible for the growth of the phytoplankton causing bloom events. In addition, bloom
occurred in the Indian Ocean Dipole years. In this paper, it has been shown that other
forcing parameters such as sea surface temperature, sea surface height, oceanic currents
and wind stress are also responsible for phytoplankton blooming. Thirteen years (19982010) climatology data were prepared and from there monthly mean anomaly was
calculated. The study area has been divided into three boxes (A,B,C) on the abundance of
phytoplankton bloom where chlorophyll-a concentrations are comparatively high bloom
ranges from 0.5-1.0 mg/m3 but patches exceeds 1.5-2.0 mg/m3 The domain within which
both the oceanographic and meteorological data were extracted were for the regions 5°N25°N latitude and 76°E-100°E longitude.
Fig.1. Monthly mean chlorophyll-a anomaly showing bloom events in Box A (5-10゜N, 9095゜E) , Box B (7-9゜ N, 80-85゜E) and Box C (9-16゜ N, 82-85゜E) are found in January 1998
December 2000, December 2005 and respectively.
3
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Fig.2. Timeseries of monthly chlorophyll-a anomal of (a ) BoxA (b) BoxB (c) BoxC
respectively. Timeseries of anomalies of Sea surface height, sea surface temperature and
chlorophyll-a of (d ) BoxA(e) BoxB(f) BoxC respectively. (g) Timeseries of chlorophyll-a of Box
A, BoxB, BoxC and Dipole mode index.
4
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APPLICATION OF BAYESIAN INVERSION TO OPTIMIZE THE PHYSICAL AND
BIOGEOCHEMICAL PARAMETERS IN OCEAN BIOGECHEMICAL MODELS
Vinu K. Valsala1*, N. Pavan Kumar1, S. Maksyutov2, R. Murtugudde3
1
Senior Scientist, Indian Institute of Tropical Meteorology; [email protected]
2
National Institute for Environmental Studies, Tsukuba, Japan
3
ESSIC, University of Maryland College Park, Maryland, USA
Bayesian inversion is a linear state estimator used in several of the earth science
related applications (Enting, 2005). Here, the possibility of the Bayesian inversion in
estimating a set of optimal values of selected physical and biogeochemical parameters in
the model for minimizing the data-model misfit is explored. At first, the parameterizations
of the surface ocean vertical mixing are optimally estimated in a linear offline tracer
transport model (OTTM) of Valsala et al., 2008. Exploiting the linear nature of the offline
modelling system, the vertical mixing profiles of selected global oceanic zones are optimally
corrected by minimizing the data-model misfit by utilizing the salinity as a control variable
and Bayesian inversion as a state estimator. The method yields optimal profiles of vertical
mixing coefficients, which, upon tailoring into the offline model yields significant error
reduction in the simulated salinity and thereby guarantying the error reductions in the
simulated model transports of any biogeochemical tracers. The study further explores the
application of the same in the optimization of biological parameters in an ecosystem model
that is coupled to OTTM by utilizing the oceanic pCO2 and phosphate profiles as the control
variables. Such optimization techniques are important in the global ocean carbon cycle
simulation and robust estimations of contemporary uptake of atmospheric CO2 by the
oceans.
References:
Enting, I. G., (2005), Inverse modeling in the atmospheric chemistry constituent transport,
Cambridge Atmospheric and Space Science Series, ISBN: 9780521018081
Valsala V., S. Maksyutov and M. Ikeda, (2008): Design and validation of an offline Oceanic
Tracer Transport Model for Carbon Cycle Study, J. Climate , Vol. 21, 2752-2769.
5
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RECENT INSIGHT ON BIOGEOCHEMICAL CONSTITUENTS IN THE COCHIN
ESTUARINE SYSTEM (CES)
K.Sriram1, Soja Louis2, C.H. Sujatha1*
1
Cochin University of Science and Technology, Cochin-16, Kerala; [email protected]
2
St. Therasa College, Department of Zoology, Cochin˗35, Kerala
Cochin Estuary is a unique complex system situated at the west coast of India, and is
environmentally more sensitive than the east coast primarily because it is bordering one of
the most sensitive ecosystems in the world, the Arabian Sea. The symptoms are there to
show considerable impact of deterioration of estuarine waters on the coastal ecosystem,
based on the emerging industrial establishments and human settlements along the west
coast of India. A number of investigations in recent years have shed light on the varied
nature of biogeochemical characteristics of the estuarine and mangrove sediments in and
around Cochin estuary. The present study intends to reveal recent trends in the
biogeochemical constituents in the sedimentary environment of the CES and also infers the
quality of the biogeochemical constituents of the studied site. For this assignment, surface
sediments (top 0-5 cm) and water samples were collected from six prominent locations of
CES during December 2014 for performing the various biogeochemical analysis (Nutrients,
Organic matter, Pigments and Trace metals). Biogeochemical evaluation of the study region
revealed that organic matter in the sediments from CES are aged and the role of protein
contribution as a potentially limiting factor for benthic consumers. Overall, C/N ratio
supports the allochthonous character of the sediments in the aquatic system and it clearly
indicates the terrestrial OM could be the dominant contributor in the study region and
make profound influence in the biogeochemical processes. The results are relevant and
serve as a measuring tool for pollution control in the Cochin Estuarine System.
Key words: Biogeochemistry, Sediment, Cochin Estuarine System.
6
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METAL FRACTIONATION PROFILE OF CORE SEDIMENTS IN THE SPECIFIC
ZONES OF COCHIN ESTUARINE SYSTEM
Nair Manju P and C.H Sujatha*
Cochin University of Science and Technology, Cochin-16, Kerala; [email protected]
The geochemical distribution of sequentially leached metal fractions (Cd, Cu, Pb, Fe,
Mn and Ni) in the core sediments sampled from three contrasting zones in the CES. These
chemical fractionation of metals are exchangeable (EXC), bound to carbonate (CA), organic
matter bound (oxidisable) (OM), iron and manganese bound (reducible) (FMO) and residual
(RES) fraction. In this study, the northern zone of the estuary was enriched with EXC fraction
for most of the metal studied. An intensification of CA fraction of metal was found for
southern and northern part of the estuary which accounts the increased agricultural and
industrial runoff in the study area. Among the metal analysed Pb, Mn and Fe are found to be
high value for FMO in this study. Cu, Fe, Pb and Mn are dominant in OM fraction in this
study under investigation. Fe and Ni are intensified in the residual fraction of the study area
indicating the lithogenic origin.
7
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SESSION-01
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22-24 March 2015
CHLOROPHYLL-A DYNAMICS IN NEAR COASTAL WATERS OF WESTERN BAY OF
BENGAL USING IN SITU AND LONG-TERM SATELLITE DATA
Aneesh A. Lotliker1*, Sanjiba Kumar Baliarsingh1, K. C. Sahu2, T. Srinivasa Kumar1
1
Indian National Centre for Ocean Information Services (INCOIS), Hyderabad 500 090; [email protected]
2
Department of Marine Sciences, Berhampur University, Odisha 7600076
The distribution of optically active substances (OAS), accuracy assessment of satellite
derived Chlorophyll-a (Chl-a) and long term trend in distribution of satellite Chl-a was
carried out at a coastal site of SATellite Coastal and Oceanographic REsearch (SATCORE)
programme. The in situ data of OAS such as Chl-a, Total Suspended Matter (TSM) and
absorption due to Coloured Dissolved Organic Matter at 440 nm (aCDOM440) along with its
spectral slope were analyzed for the period of three years (Fig. 1). The temporal distribution
of Chl-a, TSM and aCDOM440 showed one common peak during southwest monsoon season
(August-October). Apart from this Chl-a also showed a prominent peak during presouthwest monsoon (March-April). The spatial variability in TSM and aCDOM440 was
maximum during southwest monsoon whereas in the case of Chl-a it was during presouthwest monsoon. The relationship between aCDOM440 and slope parameter indicate
conservative mixing between CDOM arising from river and coastal waters (e.g., Mishra et
al., 2003).
Fig. 1: Spatially averaged monthly distribution of Chl a, b) TSM and aCDOM440 in the study
area. The vertical bars indicates the standard deviation.
The accuracy assessment of Chl-a, retrieved from Moderate Resolution Imaging
Spectroradiometer onboard the Aqua satellite (MODISA), Ocean Colour Monitor onboard
Oceansat-2 (OCM-2) and Visible Infrared Imager Radiometer Suit (VIIRS) onboard Soumi
National Polar-orbiting Partnership (NPP), showed overestimation in nearshore waters
(depth < 30m). The error in satellite estimation of Chla was in the range of 33 to 51% and
the overestimation was predominantly due to the covariance of TSM with Chla (Tilstone et
al., 2013). The Chl-a retrieved from MODISA using OC3M algorithm was most accurate with
better slope (1.001), regression coefficient (R2=0.67) and Log10RMSE (0.18 mg-m-3). The Chla retrieved from VIIRS using OC3V algorithm performed equally well (Fig. 2).
Ten years of Chl-a retrieved from MODISA was analyzed with an aim to understand its
trend in the view of bio-physical forcing (Fig. 3). The Chl-a trend in MODISA and VIIRS
matched well. Hence, VIIRS Chla can be efficiently utilized to continue time-series studies.
The bi-modal distribution of Chl-a was also clearly evident. The peak in Chl-a during presouthwest monsoon was due to phytoplankton bloom having recurring occurrence at an
annual scale (Sasamal et al., 2005).
8
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Fig. 2: Scatter plot showing the relation between in situ measured Chl-a and that derived
from a) MODISA, b) VIIRS and c) OCM-2 using sensor default algorithm. The dotted line
indicates 1:1, solid straight line shows the regression and solid curved lined shows the 95%
confidence limit.
Fig. 3: Time series distribution of spatially averaged Chl-a retrieved from sensors MODISA,
OCM-2 and VIIRS. The inset shows inside view of the rectangular box.
The source of this bloom was from the Rushikuliya estuary and surf waters and the
extent was restricted to the inshore waters having depth < 30m. The process restricting
offshore spread of high Chl-a, during pre-southwest monsoon, can be attributed to the
northward moving East India Coastal Current (EICC) which acts as a boundary between
inshore and offshore waters. The second peak in Chl-a during end of southwest monsoon
was due to upwelling and pumping of nutrients due to eddies. The shift in peak Chl-a
towards end of the monsoon might be due to the limitation in availability of sunlight due to
cloud cover and less penetration of sunlight due to high sediment from river influx
(Prasanna Kumar et al., 2010).
References:
Mishra, R.K., Shaw, B.P., Das, S.K., Rao, K.S., Choudhury, S.B., Rao, K.H., (2003) Spatiotemporal variation of optically active substances in the coastal waters off Orissa from
Rushikulya to Dhamra (east coast of India). Indian Journal of Marine Sciences 32 (2), 133140.
Prasannakumar, S., Nuncio, M., Narvekar, J., Ramaiah, N., Sardessai, S., Gauns, M.,
Fernandes, V., Paul, J.T., Jyothibabu, R., Jayaraj, A., (2010) Seasonal cycle of physical forcing
and biological response in the Bay of Bengal. Indian Journal of Marine Sciences 39(3), 388405.
Sasamal, S.K., Panigrahy, R.C., Misra, S., (2005) Asterionella blooms in the northwestern Bay
of Bengal during 2004. International Journal of Remote Sensing 26(17), 3853-3858.
Tilstone, G.H., Lotliker, A.A., Miller, P.I., Ashraf, P.M., Kumar,T.S, Suresh, T., Ragavan, B.R.,
Menon, H.B., (2013). Assessment of MODIS-Aqua chlorophyll-a algorithms in coastal and
shelf waters of the eastern Arabian Sea. Continental Shelf Research 65, 14-26.
9
SESSION-01
SESSION-01
OSICON-15
22-24 March 2015
ESTIMATION OF AEROSOL AND NUTRIENT DEPOSITION IN THE COASTAL BAY
OF BENGAL OFF VISAKHAPATNAM
K. Yadav1*, V.V.S.S. Sarma1, M. Dileep Kumar2
1
CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam-530017; [email protected]
2
CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004
Oceanic regions adjacent to Indian subcontinent are greatly influenced by the
continental sources with both natural and anthropogenic emissions. The sources,
characteristics and potential health effects of PM10 (<10μm) and PM2.5 (<2.5μm) are
different. Currently the regulatory standards for PM10 and nitrate in ambient environments
in India are 100 and 40 μg/m3 respectively. Urban areas release more suspended particles
due to heavy vehicular emissions and industries than rural regions. The studies on
evaluating the contributions of PM10 and PM2.5 to the Indian coastal regions are rather
scarce. The objective of this study is to estimate the contribution and characteristics of
these two size classes of aerosols to and in a coastal urban region (Visakhapatnam) and
estimate its impact on coastal ecosystem. We would like to test the hypothesis that most of
the coarser particles settle in the coastal regions while finer particles are transported far
from the source.
The total suspended particle (TSP) ratio of PM2.5/PM10 in the study region was 1.37 to
2.27 in the study region and it is significantly higher than reported elsewhere in the world
(0.39 to 0.86). The PM2.5 contributed to ~65% of the TSP. Higher PM2.5 particles in the study
region have their source in several industries such as thermal power and steel plants, ore
transport through open belt system etc. in Visakhapatnam. The concentrations of nitrate
and sulphates are 2 to 3 times higher in the PM2.5 than in PM10 suggesting that former size
particles can significantly influence coastal ecosystem than the latter. Since coarser particles
are expected to settle close to the coast, due to its higher density, an experiment was
conducted by collecting simultaneously TSP of PM10 on land (The Institute building, China
Waltair) closer to the coast and at ~10 km offshore (Bay of Bengal) when wind blew from
land to sea. Aerosols of PM10 were collected using a Respirable Dust Sampler during March
14 and December13. And later with the help of Ion Chromatography their ionic
concentration were measured.
Relatively higher concentrations of TSP (PM10) were observed both over land and sea
during March (76 and 60 μg/m3) compared to that in December (51 and 33 μg/m3). This
suggests that about 15 to 45% of TSP is settled in the coastal region within 10 km from the
coast and the remaining might have transported further offshore. The concentration of
nitrate was low during March both over land and sea (1.56±0.83 and 0.16±0.26 μg/m3) than
in December (2.56±1.52 and 0.64±0.30 μg/m3). Our study suggests that up to half of the
pollutants released into the atmosphere would influence the near coastal ecosystem than
hitherto hypothesized.
10
OSICON-15
22-24 March 2015
SPATIAL VARIATIONS IN TROPHIC LEVEL OF PRIMARY CONSUMERS ALONG
THE GODAVARI ESTUARY
J. Mukherjee*, V. V. S. S. Sarma
1
CSIR-National Institute of Oceanography, Regional Center, Visakhapatnam 530 017; [email protected]
Estuaries are highly dynamic environments with large spatial variations in physicochemical properties and its impact on food web dynamics is unclear. Stable isotopic
composition of carbon (δ13C) and nitrogen (δ15N) are used as a tracer to study base of the
food web supporting primary consumers and estimating the trophic level (TL) of the primary
and secondary consumers in the aquatic ecosystems. The objective of this study is to test
the hypothesis that TL of the primary consumers along the estuary need not be uniform. To
examine the same, studies have been conducted along the largest monsoonal estuary in
India, Godavari, during dry period.
Water samples for nutrients, chlorophyll-a (Chl-a), particulate organic matter (POM),
phytoplankton and mesozooplankton were collected from upper, middle and lower regions
of Godavari estuary during January 2013. Nutrients and Chl-a were measured following
standard protocols. About 50-100 specimens of different groups of phyto and zoopalankton
were picked using microscope and their isotopic composition were measured using
elemental analyzer coupled with isotope ratio mass spectrometer.
Relatively higher POM, and lower Chl-a were observed in the upper and vice versa
was found towards lower estuary. The δ13C and 15N of POM (-30.0‰, 5.5‰) suggest that
significant contribution of detritus from freshwater algae and C3 plants. In contrast,
enriched isotopic composition was observed in the lower estuary (-24‰) suggesting
significant contribution from in-situ phytoplankton. The mean 13C of mesozooplanktons (20.4‰) was relatively depleted compared to phytoplankton (-11.0‰) suggesting that the
former were not depended on the latter for feeding. Higher DOC concentrations in the
upper than lower estuary suggests that microbial loop may be operational resulting in
higher TL (2.1, 2.6) for meso and benthic plankton in the former region. In contrast, the
mean isotopic composition of mesozooplankton was close to that of both POM and
phytoplankton suggesting that either live or dead phytoplankton was used as a diet. The TL
for the zooplanktons and the benthic organisms was higher (2.3) in the upper estuary.
Similar to middle estuary, fresh in-situ phytoplankton contributed to POM pool and has
been used as diet by primary consumers. The TL for zooplanktons and benthic organisms
was the lowest (1.6) in the entire estuary. This study suggests that TL of zooplankton and
benthic organisms decreased from upper to lower estuary indicating that existence of
longer food chain at the former while shorter and classical food chain is operational at the
latter region.
11
SESSION-01
SESSION-01
OSICON-15
22-24 March 2015
A MODELLING STUDY OF BIOLOGICAL FEEDBACKS ON SEA SURFACE
TEMPERATURE
Kunal Chakraborty*, Arya Paul, Satya Prakash
Indian National Centre for Ocean Information Services (INCOIS), Hyderabad-500090; [email protected]
This paper describes the results of a coupled 3-D bio-physical model, ocean general
circulation model ROMS with an ecosystem model, which has been employed to study
biogeochemical variability in the Indian Ocean. The interannual run of the coupled set-up
has been forced using Quick-SCAT wind during the period of 01 January 2000–18 November
2009. We have applied EOFs to the weekly SST data over the Arabian Sea. EOFs do not
change structure in time, they only change sign and overall amplitude to represent the state
of the ocean. The first two EOFs explain respectively 60.21% and 26.24% of the total
variance whereas the first two EOFs of observation (AVHRR) explain respectively 60.62% and
26.12% of the total variance. However, the first two EOFs of the model without biology
explain respectively 55.76% and 29.81% of the total variance. It is clearly observed from first
two modes that biological feedback significantly improve SST in the Arabian Sea, Based on a
qualitative look of the temporal function, it is to be noted that EOF-1 and EOF-2 are
respectively associated with the semi-interannual and interannnual signal in the Arabian
Sea. It may be noted that the model with bio-geo-chemistry is able to capture the observed
variability in SST better (particularly in the western Arabian sea, where the biological activity
is significant) than the model setup without BGC module.
References:
Nakamoto, S. et al., (2000), Chlorophyll Modulation of Sea Surface Temperature in the
Arabian Sea in a Mixed-Layer Isopycnal General Circulation Model, Geophysical Research
Letters, 27, 6, 747-750.
Rao, S. A, et al., (2002), Interannual subsurface variability in the tropical Indian Ocean with a
special emphasis on the Indian Ocean Dipole. Deep-Sea Research Part II-Topical Studies in
Oceanography, 49, 1549-1572.
12
OSICON-15
22-24 March 2015
EFFECTS OF MACRONUTRIENTS ON COASTAL DIATOM GROWTH DYNAMICS
AT VISAKHAPATNAM, NW COAST OF BAY OF BENGAL, INDIA: AN
EXPERIMENTAL APPROACH
Debasmita Bandyopadhyaya* and Haimanti Biswas
CSIR National institute of Oceanography, Regional Centre, Visakhapatnam; [email protected]
Regardless of their insignificant size, marine diatoms contribute significantly to
oceanic primary production Coastal waters are usually enriched with nutrients and are
usually dominated by diatoms. Western Coastal Bay of Bengal receives significant amount of
all major nutrients through river discharge and land runoff, hence can promote diatom
growth in this area and has been reported by many earlier studies. However supply of the
major nutrients (nitrate, silicate and phosphate) to the coastal waters may not be uniform
and their differential loading can potentially alter growth and biomass production in coastal
diatom communities. Unlike other microalgae found in the coastal waters, diatoms demand
a significant amount of silicate along with nitrate and phosphate owing to their siliceous
frustules. Production of biogenic silica can be dependent not only on silicate concentrations,
but also on nitrate and phosphate. We have conducted a series of microcosm experiments
using natural diatom communities from the Visakhapatnam coast to understand, growth
rate, utilization rate of silicate and biogenic production in presence of variable nitrate and
phosphate concentrations. Our experimental results revealed that when nitrate and silicate
were present in 1:3 concentration, the maximum growth rate (0.78μ d-1) was less than when
it was given in 1:1 concentration (0.85 μ d-1). This is in well agreement with the classical
Redfield ratios. Biogenic silica production also followed a similar trend. Additionally,
increasing phosphate concentration also helped to enhance biomass, silicate uptake and
biogenic silica production till a certain level (4 - 4.5µmol L-1), however, did not affect
thereafter. Increasing silicate concentration in the presence of excess nitrate only showed
an enhancement in BSi:Chla ratios, however did not show any change in Chla concentrations
in the treatments. We infer that coastal diatoms can only utilize the supplied nutrients
efficiently when other nutrients are present in optimum concentrations and hence
periodical loading of a particular nutrient may not promote growth, biomass and biogenic
silica production in the study area and can remain unutilized.
13
SESSION-01
SESSION-01
OSICON-15
22-24 March 2015
VARIATIONS IN EFFICIENCY OF BIOLOGICAL PUMP IN THE BAY OF BENGAL
USING STABLE ISOTOPIC COMPOSITION OF NITROGEN IN THE SUSPENDED
MATTER
C.K. Sherin* and V.V.S.S. Sarma
CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, 530 017; [email protected]
The Bay of Bengal is known as low productive basin compared to its western
counterpart, the Arabian Sea, due to strong stratification imposed by high river discharge
lead to inhibition of vertical nutrients input. Despite such low production, sinking carbon
fluxes to the deep ocean were almost similar in both the basins and were attributed to the
ballast effect in the Bay of Bengal. Here we aim to examine the efficiency of biological pump
in terms of f-ratio (the fraction of production supported by new nitrogen to the total
production) and its spatial variability in the Bay of Bengal during post monsoon (NovemberDecember 2013), using stable isotopic composition of suspended particulate nitrogen (PN)
in the upper ocean.
The surface water samples were collected along the cruise track at one degree interval
and ~20-30 L of water filtered through pre-combusted grass fibre (GF/F) filter under low
vacuum. The concentration and isotopic composition of carbon and nitrogen in the
suspended matter (SPM) was measured using Elemental Analyser coupled with Isotopic
Ratio Mass Spectrometer (Delta V Plus, Thermo Electron, Germany) and vertical distribution
of nitrate concentration was measured using sensor.
The nitrogen isotopic composition of PN (δ15Nsus) ranged from 1.8 to 6.3‰ with higher
values in the southern and western than northern and central Bay and has strong inverse
relation with depth of nitracline indicating that subsurface nitrate is supporting the
production in the Bay of Bengal during study period. The mean C/N ratios (6.9±0.8) and
(-25.3±0.5‰) indicating that SPM was mainly derived from in situ sources. Based
on the δ15Nsus and the slope of the relation between δ15Nsus and nitracline depth, the f-ratio
was computed using the mass balance approach. Since δ13Csus of SPM is close to that of
marine origin, we assumed that the isotopic composition of SPM represents phytoplankton
and δ15Nsus NO3 of deep water as 5‰, which is a global mean deep water NO3 value. The
computed f-ratios varied from 0.29 to 0.72 with relatively higher ratios in the south
(0.56±0.12) than northern Bay (0.39±0.1). This suggests that higher fraction of the primary
production is leaving the photic depth in the southern than northern Bay. The higher f-ratio
in the southern bay is associated with shallow nitracline suggesting that higher sinking fluxes
in the Bay of Bengal were mainly driven by in situ production supported by physical
processes. This study suggests that higher sinking organic carbon fluxes in the Bay of Bengal
were supported by in situ processes than hitherto hypothesized.
14
OSICON-15
22-24 March 2015
INTRA-ANNUAL VARIABILITY IN ORGANIC CARBON SINKING FLUXES OFF A
TROPICAL MAJOR RIVER, GODAVARI: SEDIMENT TRAP RESULTS
Sreenu Lenka*, M. S. Krishna and V.V.S.S. Sarma
CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, India – 530017; [email protected]
Export of organic matter (OM) to the seafloor and its subsequent burial in ocean
sediments is a sink for atmospheric carbon dioxide (CO2) on geological time scales. However,
in-situ biological production of OM, terrestrial OM input through river discharge, rate of
sedimentation and preservation conditions largely controls the OM sinking fluxes in coastal
regions. Here, we present the results of sinking particulate matter collected for one year
from two sediment traps deployed at 350m and 1000m below the surface at off the major
monsoonal river, Godavari, central east coast of India. Content and stable isotope ratios of
carbon and nitrogen were determined to understand possible sources and transformation
of OM in the water column and to estimate sinking fluxes of OM to the seafloor from this
region. Annual mean mass fluxes were found to be 2.46±2.2 (range: 0.23 - 9.62 g m-2 d-1)
and 1.76±1.33 g m-2 d-1 (0.24 - 5.00 g m-2 d-1) in the shallow and deep traps, respectively.
These fluxes are relatively higher than those fluxes reported from similar depths in the
northern and central Bay of Bengal. Mean mass fluxes were found to be higher by ~10-folds
in both shallow (mean: 4.83±2.6 g m-2 d-1) and the deep (3.14±1.36 g m-2 d-1) traps during
discharge (June - September) period than during no discharge period. It is attributed to the
influence of freshwater discharge from the major monsoonal river, Godavari which supplies
~170x106 tons yr-1 of suspended sediment and 2.81x106 tons yr-1 of POM to the Bay of
Bengal through discharge. Estimated sinking fluxes of OC ranged from 0.3 - 237 and 0.3 - 71
mg m-2 d-1 in the shallow and deep traps, respectively, with a higher fluxes of 100-fold
during discharge and 30-fold during no-discharge periods. The range of δ13C, δ15N and
elemental OC:TN ratios in the shallow (-22.1 to -19.4‰, 4.6-8.5‰, 8-14, respectively) and
deep (-21.6 to -19.3‰, 3.2-6.1‰, 8-12) traps indicate that the POM is a mixture of OM
derived from both allochthonous and autochthonous sources
15
SESSION-01
SESSION-01
OSICON-15
22-24 March 2015
SOURCES AND DISTRIBUTION OF PARTICULATE ORGANIC MATTER IN THE
WESTERN COASTAL BAY OF BENGAL DURING SW MONSOON: INFLUENCE OF
RIVER DISCHARGE
M.S. Krishna*, L. Gawade, S.A. Naidu, V.V.S.S. Sarma, N.P.C. Reddy
CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, 530017; [email protected]
In order to understand the influence on the composition of particulate organic matter
(POM) of river discharge, a study was conducted along the western coastal Bay of Bengal
during SW monsoon (discharge period). Elemental and stable isotope ratios of carbon and
nitrogen showed that POM is a mixture of OM derived from autochthonous and
allochthonous sources, with a predominance of the former in the north western (NW) and
latter in the south western (SW) parts of the coastal Bay of Bengal during study period. Dual
isotope mixing model ‘SIAR’ revealed that OM derived from terrestrial C3 plants contributes
predominantly (~75%) than the contribution from marine phytoplankton derived OM
(~20%) to POM in the SW region. On the other hand, phytoplankton derived OM dominates
(~60%) the POM, with a minor contribution from terrestrial C3 (~20%) and C4 plants (~20%)
in the NW region. A predominance of the allochthonous POM in the SW region is attributed
to transport through discharge of terrestrial vascular plant material by the major rivers
Godavari and Krishna during SW monsoon. In addition, relatively high suspended load
(20.6±8.6 mg l-1) limits the light availability to phytoplankton resulting in relatively low
biological production (Chl-a: 1.3±0.9 mg m-3) in the SW region. By contrast, major
contribution from autochthonous sources in the NW region could be due to enhanced
biological production (Chl-a: 3.2±2.7 mg m-3) supported by conducive conditions for
phytoplankton to grow. Relatively low suspended load (12.0±5.8 mg l-1) in the NW region
increases in-situ biological production by allowing light availability to deeper depths for
phytoplankton. Therefore, freshwater discharge along with nutrients and suspended matter
has a significant influence on the composition of POM in the western coastal Bay of Bengal
during SW monsoon.
16
OSICON-15
22-24 March 2015
SENSITIVITY OF COASTAL PHYTOPLANKTON TO VARIABLE COPPER
CONCENTRATIONS FROM THE VISAKHAPATNAM COAST (SW COAST OF BAY
OF BENGAL, INDIA)
Haimanti Biswas* and Debasmita Bandyopadhyay
CSIR National Institute of Oceanography, Regional Centre, Visakhapatnam; [email protected]
Copper (Cu) a redox-active transition metal plays dual role in phytoplankton
physiology depending on its concentrations; at lower concentrations Cu plays numerous
roles in oxidation-reduction reactions of many physiological processes like photosynthesis
and respiration; conversely, at higher concentrations, Cu has mostly been considered as
toxic for being able to make strong complexes with biomolecules and numerous studies
showed various types of deleterious effects on marine phytoplankton. Coastal waters
receive significant amount of copper from different anthropogenic sources and can be
deleterious to coastal phytoplankton. However, when living permanently in a metal
enriched environment, coastal phytoplankton also may develop some adaptability to
tolerate metals levels and to overcome the stress, marine phytoplankton was found to
control their internal Cu pool well below the toxic level and this capability was
species/genera specific. Visakhapatnam coast is under direct anthropogenic pressure due to
the vicinity of port, naval base and many industries which may release significant amounts
of toxic metals including Cu in the adjacent coastal waters. In our earlier studies we have
shown that Cu may play a vital beneficial role in coastal phytoplankton physiology, however,
our knowledge about the sensitivity of coastal phytoplankton communities to different Cu
concentrations on a spatial scale is almost scarce. The impact of variable Cu concentrations
(till 1000nM) was investigated on coastal phytoplankton communities from different
distances (0km, 1km and 10km) from the Visakhapatnam coast. Our results revealed that
the coastal phytoplankton which are just found adjacent to the coast are highly tolerant to
Cu level up to > 100nM which is consistent with our earlier studies. Moreover, at 1000nM
Cu level, phytoplankton growth was severely inhibited (3.5 times). Diatoxanthin index was
also increased with increasing Cu concentrations which indicates the presence of oxidative
stress by this redox metal at higher concentrations. When the phytoplankton communities
from 1km far from the coast were grown with variable Cu levels, a slight enhancement in
growth up to 25nM were observed and was almost diminished at 50nM Cu level.
Interestingly, when moving further from the coast ( 10km), phytoplankton biomass
decreased significantly at 10nM Cu level and 20-50% reduction in biomass was observed.
Our results indicate that coastal waters in the study area are enriched with metals like Cu,
however, the coastal species are quite adaptive to higher Cu concentrations and further
increase many largely impede their growth. Nonetheless, those species inhabiting far from
the coast are still highly vulnerable to higher Cu level and further metal enrichment may
cause significant damage to them. This can have a large biogeochemical significance in the
coastal waters.
17
SESSION-01
SESSION-01
OSICON-15
22-24 March 2015
BIO-PHYSICAL COUPLING AND UPPER OCEAN BIOLOGICAL PRODUCTIVITY IN
THE NORTHERN INDIAN OCEAN
S. Prasanna Kumar* and Jayu Narvekar
CSIR-National Institute of Oceanography, Dona Paula, Goa-403 004; [email protected]
Bio-physical coupling is an important aspect in the production of organic carbon in the
euphotic zone. In a top-down system the primary production and subsequent chlorophyll
biomass in the upper ocean is controlled by the availability of sunlight, macronutrients such
as nitrate, phosphate and silicate, and micro nutrients such as iron. In addition to this,
grazing by zooplankton also is an important factor in the build-up of chlorophyll biomass.
Through this presentation we synthesize the information on the former using 2 decades of
collocated data on physical and biogeochemical parameters collected onboard Indian
research ships following stringent protocol during Joint global ocean flux studies in the
Arabian Sea (JGOFS, 1992-1997), Bay of Bengal Process Study (BOBPS, 2001-2006) and
equatorial Indian Ocean Process Study (EIOPS, 2005- 2012). The salient features that
emerged out of these studies are the role of winter convection driving the winter bloom,
while a combination of coastal upwelling, advection, wind-mixing and upward-Ekman
pumping supporting the high summer chlorophyll biomass in the Arabian Sea. The column
integrated chlorophyll as well as primary production, based on in situ measurements,
depicted the signatures of winter and summer blooms, which was also discernible from
satellite derived chlorophyll pigment concentration. In contrast, in the Bay of Bengal, the
satellite derived chlorophyll pigment concentration showed very low level of chlorophyll
biomass, with very weak seasonality. However, the integrated chlorophyll as well as primary
productivity, though low compared to Arabian Sea, showed sustained levels of biomass and
production with winter values slightly higher than summer values with no defined
seasonality. These results along with the results from sediment trap data on sinking organic
carbon flux at mid-depth (~1000m) suggest role of meso-scale eddies in enhancing and
sustaining elevated chlorophyll biomass and primary production. The strong stratification
during summer monsoon makes the Bay a less productive basin due to lack of strong
upwelling as well as wind-mixing. In addition to meso-scale eddies, the tropical cyclones
that occur regularly during spring and fall intermonsoons contribute to the production of
organic carbon during these seasons. In the equatorial region, however, the satellite
derived chlorophyll pigment concentration showed higher values only in the western and
central region during summer monsoon, which is associated with upwelling. During the rest
of the year the upper ocean waters in the equatorial region is oligotrophic making it an
oceanic desert. This situation alters during Indian Ocean Dipole (IOD) years when eastern
equatorial Indian Ocean becomes productive with chlorophyll blooms, which advect
westward impacting even the central parts as well. In the equatorial Indian Ocean apart
from IOD, propagating waves also impacts the upper ocean nutrients and chlorophyll.
18
OSICON-15
22-24 March 2015
EFFECTS OF ZINC ON COASTAL PHYTOPLANKTON GROWTH AND PRIMARY
PRODUCTION UNDER LOW AND HIGH CO2 LEVELS FROM VISAKHAPATNAM
COAST
Aziz Ur Rahman Shaik1*, Debasmita Bandyopadhyay2 and Haimanti Biswas3
1
CSIR National Institute of Oceanography, Regional Centre, Visakhapatnam, India; [email protected]
Zn is one of those bioactive trace metals that play significant role in plant physiology
and biochemistry. However, like other metals, Zn is also toxic at higher level and can create
several damages to coastal and marine phytoplankton. Zn is present as a cofactor in one of
the most important enzymes involved in carbon metabolism, carbonic anhydrase (CA).
Additionally, Zn is involved in synthesizing numerous plant proteins, a process of chlorophyll
synthesis, DNA base pair repairing, photosynthetic-D1 protein repairing and hence
variability in Zn availability may significantly affect plant physiology. Coastal waters are believed
to be metal enriched, however, also can be limiting sometimes due to high variability in its input rate from
riverine, land runoff and atmospheric sources. Incubation experiments were conducted using
natural phytoplankton communities which are mostly diatom dominated from the
Visakhapatnam coast in order to understand the responses of coastal phytoplankton to
added Zn under low and high CO2 levels. Our results revealed that under both low
(200µatm) and high (1500µatm) CO2 levels, Zn showed significant effect on coastal
phytoplankton physiology. Chla normalized photosynthetic oxygen evolution rate showed
almost 27% higher values in the low CO2 treatment where Zn is added relative to the control
(without Zn addition). High CO2 treated samples without Zn showed very high values (almost
200%) of photosynthetic oxygen evolution relative to the controls. However, in the
treatments with high CO2 and Zn, the same rate was reduced. Particulate organic carbon
and nitrogen including total protein also revealed a similar trend. Interestingly the highest
concentrations of total protein and chlorophyll and the lowest concentration of biogenic
silica (BSi) were detected at high CO2 and Zn added treatments. Biogenic silica to organic carbon
ratios (BSi:POC) were 2.42 % higher at low CO2 and Zn treated samples than that of Zn untreated samples;
whereas 2.95% lower at high CO2 plus Zn treated samples relative to the high CO2 alone. Total protein
concentration was maximum and BSi was minimum at high CO2 and Zn added treatments. Thus, these
results indicate that at low CO2 levels, Zn addition enhances photosynthetic oxygen evolution and it could
be due to the involvement of the enzyme CA in inorganic carbon acquisition. Therefore, under low CO2 plus
Zn treated treatments, no inhibitory impacts were observed. Under the high CO2 treatments, low pH (<7.6)
of the water might increase the bioavailability of the metals and hence of Zn which could be beyond their
requirements and hence showed lower photosynthetic rates. Moreover, excess Zn can largely inhibit
silicate transport and hence might have hindered BSi production under high CO2 plus Zn added samples.
Higher total protein and chlorophyll at this treatment indicates the involvement of Zn in both these
processes. Thus we presume that Zn plays a significant role in coastal phytoplankton physiology,
nonetheless, can also impede some other cellular processes at higher availability.
19
SESSION-01
SESSION-01
OSICON-15
22-24 March 2015
DISTRIBUTION OF BIOCHEMICAL COMPOUNDS IN INDIAN MONSOONAL
ESTUARIES DURING SW MONSOON
B.S.K. Kumar1*, V.V.S.S. Sarma2, M.S.R. Krishna2 and N.P.C. Reddy2
1
Andhra University, Visakhapatnam-530003; [email protected]
CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam, 530 017
2
Rivers are the major source of suspended matter (SPM), nutrients and organic matter
(OM) to estuaries and coastal oceans, and establish a major link between land and ocean.
However, the quality of the material depends on the drainage intensity and bed
composition of the catchment. Here, we present the results of a systematic study conducted
during SW monsoon in 27 major and medium Indian monsoonal estuaries. As the discharge
from these rivers is dependent on the monsoon induced precipitation over the Indian
subcontinent, which shows a large spatial variability, the discharge ranged from as low as 28
to 3500 m3 s-1. As the OM derived from in situ & terrestrial sources was reported to have
distinctly different concentrations of proteins (TPRO) and carbohydrates (TCHO), the ratio
of protein to carbohydrates can be used to identify the source of OM. Relatively lower
TPRO:TCHO ratios were found in the northern estuaries (0.85±0.48), which receives
relatively high river discharge along with high suspended matter, than the south east (SE)
estuaries (1.56±1.21) indicating that degraded/ modified OM is predominant in the former,
whereas freshly produced in situ OM in the latter. Relatively high concentration of Chl-a
confirms the predominance of in situ OM in the SE estuaries. The ratio is in between 0.5 and
1.8 in the SW estuaries, suggesting that the OM is a mixture of in situ produced and
terrestrial OM. It is estimated that the Indian estuaries transport 1.3x 109, 1.6x 108, 8.0x108
g C to Bay of Bengal, and 6.5x 108, 1.9x 107, 3.6x108 g C to Arabian Sea during discharge
period in the form of TCHO, DFAA and TPRO respectively. This study demonstrates that the
OM in the northern estuaries is mainly contributed by terrestrial sources, whereas it is a
mixture of in situ and terrestrial OM in the southern estuaries.
20
OSICON-15
22-24 March 2015
OBSERVED INTRA-SEASONAL VARIABILITY OF CHLOROPHYLL-A USING ARGO
PROFILING FLOAT IN THE EASTERN EQUATORIAL INDIAN OCEAN
V. P. Thangaprakash*, M. S. Girishkumar, T.V.S. Udaya Bhaskar, M. Ravichandran
ESSO – Indian National Centre for Ocean Information Services, Hyderabad; [email protected]
Madden-Julian Oscillation (MJO) [Madden and Julian, 1994], a dominant intraseasonal
mode in the tropical climate, can significantly modulate oceanic physical, dynamic and
biogeochemical characteristics. Even though, earlier studies have examined the impact of
MJO on physical and dynamical variability of ocean state, its impact on chlorophyll
variability is limited due to lack of systematic measurements of in-situ observation [Jin et al,
2013]. The understanding of these processes is of importance not only for geophysical
interest but also for the prediction of biological activities which is directly related to fishing
industries. Analysis of two years (2013-2014) time-series of vertical profile of chlorophyll-a
data obtained from a Argo profiling float (WMO ID - 2902088) in eastern equatorial Indian
Ocean showed that modulation of near surface (< 30 m) chlorophyll (> 0.8 mg/m3) in subseasonal times scale. Our analysis shows that the existence of strong connection between
MJO and enhancement of chlorophyll in the near surface layer. Further, presence of
subsurface chlorophyll maxima, a well know characteristics of vertical structure of
chlorophyll in the tropical climate, in depth range of 40-60 m has been noticed. Our analysis
showed that, the deepening of mixed layer in to subsurface chlorophyll-a due to increasing
wind field associated with MJO activity initiated the near surface bloom. However, all MJO
events might not lead to near surface bloom. Further, the strong connection between the
depth of subsurface chlorophyll maxima (in the presence of shallow thermocline) and
enhancement of near surface bloom with MJO event has been noticed.
References:
Jin, D., R. Murtugudde, and D. E. Waliser (2013), Intraseasonal atmospheric forcing effects
on the mean state of ocean surface chlorophyll, J. Geophys. Res. Oceans, 118, 184–196, doi:
10.1029/2012JC008256.
Madden, R. A., and P. R. Julian (1994), Observations of the 40–50-Day Tropical Oscillation—
A Review, Mon. Weather Rev., 122(5), 814–837.
21
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VARIABILITY OF PHYTOPLANKTON PIGMENT CONCENTRATION IN INDIAN
ESTUARIES DURING PEAK RIVER DISCHARGE PERIOD
D. B. Rao1*, V.V.S.S. Sarma2, M.S. Krishna2 and N.P.C. Reddy2
1
CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam; [email protected]
2
CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam
The intensity of monsoonal precipitation shows significant spatial variability over
Indian subcontinent resulting in variable magnitude of discharge from Indian
rivers/estuaries. Discharge brings significant amount of terrestrial nutrients to the estuary to
support phytoplankton biomass. India ranks second in the world, in fertilizer usage with
significant spatial variability and the excess fertilizers are expected to land in the
rivers/estuaries. The artificial nutrients, such as fertilizers, not only increase concentrations
but also ratios of nitrogen to phosphorus that would have significant impact on
phytoplankton composition. The nitrogen isotopic composition of particulate nitrogen
(δ15NPN) was lower (0.2 to 4‰) in the estuaries receiving high discharge and vice versa in
low discharge estuaries (5.0 to 16.7‰) suggesting that artificial and regenerated nutrients
are supporting primary producers.
To examine the impact of magnitude of river discharge and contribution of artificial
nutrients on diversity of phytoplankton composition in the estuary; water samples were
collected from 27 major and medium estuaries along Indian coast during the peak discharge
period. About 0.5-1 L of water samples were filtered through Glass Fiber (GF/F) filters and
the pigment retained on the filter was extracted with acetone and the composition was
measured using HPLC (High performance liquid chromatography).
The rate of river discharge varied between 28 and 3505 m3s-1 in the Indian estuaries
and relatively higher discharge was observed in the estuaries located in the northern India.
The concentrations of SPM was higher by an order of magnitude (223 ± 83mg/l) in the
estuaries that received higher discharge (>500 m3s-1) than low discharge estuaries
(29.7±12mg/l). The concentration of phytoplankton biomass (Chl-a) was higher (6.9μg/l) in
the low discharge estuaries than high discharge estuaries (3.2μg/l) due to suppression of
growth by less availability of light in the latter estuaries. The Fucoxanthin to Zeaxanthin
(F/Z) ratio was low (0.4) in the high discharge estuaries than that (0.6) in low discharge
estuaries suggesting that high turbidity did not promote diatoms as they require relatively
higher light conditions. Lower F/Z ratio (0.2) was observed in the estuaries received
relatively higher fertilizer inputs, indicated by depleted 15NPN, than estuaries received
regenerated nutrients (0.9) suggesting that artificial nutrients promoted picoplankton. In
addition to this low N:P ratios (3) were observed in the estuaries received artificial nutrients
than regenerated source (10) suggesting that modification of ratios further influenced
phytoplankton composition in the Indian estuaries. Several dams have been constructed on
many of the Indian rivers and the discharge is controlled by the dam authorities. Our study
revealed that modification of discharge and concentrations of artificial nutrients modify
phytoplankton composition in the Indian estuaries and may have significant impact of the
food-web dynamics.
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INTERANNUAL TO LONG-TERM VARIABILITY OF OXYCLINE ALONG THE WEST
COAST OF INDIA: UNDERSTANDING ANOXIC EVENTS THROUGH MODELING
APPROACH
V. Parvathi1*, I. Suresh1, S. Neetu1, M. Lengaigne1,2, M. Levy2, L. Resplandy3, C. Ethé2, J.
Vialard2, O. Aumont2, H. Naik1, SWA. Naqvi1
1
CSIR-National Institute of Oceanography, Goa, India; [email protected]
Laboratoire d'Océanographie Expérimentation et Approches Numériques, Paris, France
3
Scripps Institution of Oceanography, La Jolla, California, United States
2
Arabian Sea hosts one of the major open ocean oxygen minimum zones (OMZ) in the
world's ocean. During the Indian summer monsoon, the continental shelf off the west coast
of India experiences strong upwelling. The upwelling low-oxygen, high-nutrient waters lead
to the formation of the world’s largest natural low-oxygen zone over the continental shelf
off the Indian west coast during the post-southwest monsoon. During some years, these
waters turn completely oxygen depleted, a condition called coastal anoxia. These anoxic
events exhibit strong decadal and interannual variabilities and are reported to have been
intensified by the turn of 20th century. However the mechanisms that cause oxygen
variability along the west coast of India have not yet been understood. In the present study,
we address this issue using an Indian Ocean regional configuration of NEMO/PISCES
biogeochemical model. We show that the depth of oxycline along the western coast of India
display considerable decadal fluctuations, along with interannual ones, with a shoaling from
the late 70’s until 2000 and a deepening since then. These variations agree qualitatively well
with the sparsely available oxygen measurements over the past 40 years. Our analysis
indicates that these fluctuations are intimately tied to the decadal and interannual
fluctuations of the thermocline depth, suggesting that the variability in the oxygen along the
west coast of India are mainly controlled by physical mechanisms, largely related to natural
variability.
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VERTICAL VARIATION OF PRIMARY PRODUCTIVITY IN PRESENCE OF
ULTRAVIOLET RADIATIONS, CENTRAL WEST COAST OF INDIA
Prachi A. Naik1*, M. Gauns2
1
CSIR-National Institute of Oceanography, Goa; [email protected]
2
CSIR-National Institute of Oceanography, Goa
West cost of India is strongly influenced by monsoonal cycle. High primary
productivity in the region is observed during southwest monsoon (SWM) due to nutrient
rich upwelled waters from intermediate depths (Naqvi et al., 2006). High oxygen demand for
respiratory oxidation of the organic carbon produced during senescent phase of SWM endsup in development of oxygen deficient zone (hypoxia), a few meters below the surface
(Naqvi et al., 2000) thus becomes a global environmental problem. A resolute redressal to
the problem lies in regulation of primary productivity of the region to optimal levels which is
exhibited by dual nature of incoming solar Ultraviolet (UV) radiations observed along with
Photosynthetically Active Radiation (PAR, 400-700 nm); as a consequence of atmospheric
ozone depletion. The UV-B radiations (280-325 nm) are well known stressor (Häder, 2003)
and reduce photosynthetic rates (Steemann Nielsen, 1964; Helbling et al., 2003). On the
contrary, UV-A radiations (325-380 nm) have been reported to cause repair of UV-B-induced
DNA damage (Buma et al., 2003) and enhance fixation of carbon dioxide (CO2) (Nilawati et
al., 1997; Barbieri et al., 2002) by the phytoplankton community.
Our study addresses verification of the regulatory effect of solar UV radiations on
primary productivity of coastal waters with reference to quantum efficiency of photosystem
II (PS II) photochemistry expressed in terms of Fv/Fm ratio (Kolber and Falkowski, 1993) and
phytoplankton biomass. The estimation of primary productivity was fluorescence-based;
following the Kolber and Falkowski model 1993 (Suggett et al. 2001). Vertical profiles of
solar irradiances of UV and PAR radiations and variable active fluorescence were obtained
with commercial UV-PAR Radiometer and Fast Repetition Rate Fluorometer (FRRF) at a
coastal station of eastern Arabian Sea (15°30.490’’N and 73°39.108’’E) during SWM of 2013
(September, October) and 2014 (July and October) as shown in Figure 1 A, B, C & D
respectively. Upper 20m water column of the study region was euphotic and exposed to
solar UV radiations along with PAR irradiance. The variation pattern of chlorophyll a (Chl a)
concentration, Fv/Fm ratio in presence of UV and PAR irradiance to the variation of PP in the
water column had highest coefficient of correlation observed for PP to UV-A & UV-B
radiations followed by Fv/Fm, Chl a concentration and PAR irradiance (Table 1). The
strength of irradiance of UV-B to UV-A except at Oct 2013 is lower wherein, at 10-15m
column a 40% rise in Fv/Fm was seen to minimize the decrease in PP from 80% to 60% in
presence of 20% rise of UV-B irradiance. The vertical decreased gradient in PP (Sep 2013)
was similar to the reduced UV-A irradiance. In the year 2014 where the variation in UV-A
and UV-B irradiance was consistent in the water column with UV-A greater than the UV-B
irradiance (approximately twice), the variation in PP was simultaneous to the varying FV/Fm
values. During the study period in waters off-Goa, the combined regulatory effect of UV-A
and UV-B irradiance on primary productivity was seen but requires to be quantified.
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References:
Barbieri, E. S., Villafañe V. E., Helbling E. W. (2002), Experimental assessment of UV effects
on temperate marine phytoplankton when exposed to variable radiation regimes, Limnology
and Oceanography, 47, 1648–1655.
Buma, A. G. J., Boelen P., Jeffrey W. H. (2003), UVR-induced DNA damage in aquatic
organisms, In UV Effects in Aquatic Organisms and Ecosystems, Helbling E. W., Zagarese H. E.
(eds.), Royal Society of Chemistry, Cambridge, UK, 291–327.
Häder, D. P. (2003), Effects of solar ultraviolet radiation on aquatic primary producers, In
Handbook of Photochemistry and Photobiology, Nalwa H.S. (ed.), American Scientific
Publishers, IV, Stevenson Ranch, CA, 329–35.
Helbling, E. W., Gao K., Goncxalves R. J., Wu H., Villafañe V. E. (2003), Utilization of solar UV
radiation by coastal phytoplankton assemblages off SE China when exposed to fast mixing,
Marine Ecology Progress Series, (259), 59–66.
Kolber, Z., Falkowski P. G. (1993), Use of active fluorescence to estimate phytoplankton
photosynthesis in situ, Limnology and Oceanography, 38(8), 1646-1665.
Nilawati, J., Greenberg B. M., Smith R. E. H. (1997), Influence of ultraviolet radiation on
growth and photosynthesis of two cold ocean diatoms, Journal of Phycology, 33, 215–224.
Naqvi, S. W. A., Jayakumar D. A., Narvekar P. V., Naik H., Sarma V. V. S. S., D’Souza W.,
Joseph S., George M.D. (2000), Increased marine production of N2O due to intensifying
anoxia on the Indian continental shelf, Nature, 408, 346–349.
Naqvi, S.W.A., Narvekar P.V., Desa E. (2006), Coastal biogeochemical processes in the North
Indian Ocean (14, S-W), In The Sea, Vol. 14B, Robinson A.R., Brink K.H. (eds.), Harvard
University Press: Cambridge, MA; 723–781.
Steemann Nielsen E. (1964), On a complication in marine productivity work due to the
influence of ultraviolet light, Journal du Conseil International pour l'Exploration de la Mer,
29, 130–135.
Suggett D., Kraay G., Holligan P., Davey M., Aiken J., Geilder R. (2001), Limnology and
Oceanography, 46(4), 802-810.
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INFLUENCE OF ANTHROPOGENIC ACTIVITIES ON ABUNDANCE OF
HETEROTROPHIC AND PATHOGENIC BACTERIA ALONG THE COAST OF
ANDAMAN ISLANDS
P. Sudharani*, Y. Sathibabu, T. N. R. Srinivas
CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam; [email protected]
Anthropogenic activities bring land-derived material and fauna to the coastal regions,
including heterotrophic and pathogenic bacteria, which may have significant impact on
health of the coastal ecosystem. Heterogeneity in their distribution is expected due to
variable characteristics of the discharge water from different rivers (from Myanmar) and
anthropogenic activities in the islands which receive various degree of anthropogenic
pressure. In order to examine the influence of anthropogenic activities on the coastal
ecosystem along the coast of Andaman Islands, a study was conducted to examine
abundance of heterotrophic and pathogenic bacteria (Aeromonas hydrophila, Escherichia
coli, Enterococcus faecalis, Pseudomonas spp., Salmonella spp., Shigella spp. and Vibrio
spp.) during monsoon season.
Samples were collected on board ORV Sindhu Sadhana (#SSD-001) during 1st August
to 16th August 2014, from 24 stations (15 east side and 9 west side) around Andaman
Islands. The bacteriological examinations were done onboard laboratory following standard
protocols for the enumeration of total, heterotrophic and few pathogenic bacteria. Other
physico-chemical parameters were studied following standard protocols.
The total microbial counts showed variation with reference to the particular organic
carbon and Chlorophyll concentrations. The heterotrophic and pathogenic bacterial counts
(Escherichia coli strain O157:H7 and Enterococcus faecalis) were high across 10o channel as
it is a major shipping channel to Andaman Sea. Relatively higher counts of total,
heterotrophic and pathogenic bacteria (Aeromonas hydrophila, Escherichia coli strain
O157:H7 and Enterococcus faecalis), were observed in the coastal region compared to
offshore may be due to release of domestic untreated sewage in the former zone.
Pseudomonas spp., Salmonella spp., Shigella spp. were not detected in the study region
while Vibrio spp. were sparsely detected. Relatively fewer counts were observed in the east
coast of Andaman Islands comparative to western coast. The presence of Escherichia coli
strain O157:H7 and Enterococcus faecalis counts at several stations indicate that untreated
domestic sewage contaminated with human faeces was released into the coastal waters
which is more intensified during monsoon season and its condition is unhygienic during this
season, however its impact on the ecosystem needs more studies. But comparative to the
east coast of Bay of Bengal (Visakhapatnam offshore data) the bacterial counts including
pathogenic bacteria were an order of magnitude lower.
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BENTHIC REMINERALIZATION AND NUTRIENTS EXCHANGE ALONG THE
SALINITY GRADIENT OF A TROPICAL ESTUARY, CENTRAL WEST COAST OF
INDIA
A. K. Pratihary*, J. Araujo, K.F. Bepari, R. Naik, S. Morajkar, P. Satardekar, D.M. Shenoy,
S.W.A. Naqvi
CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004; [email protected]
Estuaries are transitional biogeochemical zones between two contrasting ecosystems
i.e. terrestrial and oceanic, and receive significant amount of organic carbon and nutrients
such as NO3-, NH4+, PO43- and SiO44- through natural and/or anthropogenic sources. The
health of the estuary is largely determined by the fact whether these extraneous carbon and
nutrients undergo any biogeochemical processing in the estuary or are discharged to the
coastal sea without undergoing any transformation.
The Mandovi estuary is a tropical, monsoonal and macrotidal estuary located along
the central west coast of India. It experiences dramatic change in salinity and nutrients
between the dry season (October-May) and the monsoon season (June-September). During
the monsoon it becomes almost a fresh water body (Salinity = 0-4 psu) owing to heavy
precipitation and land run-off. In contrast the estuary becomes tidal-dominated during the
dry season and develops a prominent salinity gradient based on which the estuary could be
divided broadly into three salinity zones i.e. marine (30-33 psu), brakish (20-25 psu) and
freshwater (0-5 psu). To understand the geochemical control of salinity on the benthic
remineralization and nutrient fluxes across sediment-water interface, a series of intact-core
incubations were carried out along the salinity gradient. The cores were collected from
Betim (32 psu), Amona (20 psu) and Ganjem (5 psu) during May-June 2014 and incubated
both aerobically and anaerobically in the laboratory at controlled temperature under dark
for 4-5 days Samples were collected at 6-12h interval for dissolved O2, N2O and nutrients.
Separate sediment cores were also collected from these sites for organic carbon, porosity,
and porewater nutrients and salinity.
Results showed that benthic respiration rates decreased linearly from 71 to 36 mmol
m-2 d-1 from Betim to Ganjem resulting in a decrease in benthic mineralization rate from 68
to 31 mmol m-2 d-1 along the salinity gradient even as Corg increased from 1.7 to 8.5%
upstream indicating dominance of refractory Corg towards upstream. Estuarine sediment
behaved as a net source of DIN (dissolved inorganic nitrogen i.e. NO3-+NO2-+NH4+) to the
overlying water though DIN efflux decreased from 2.59 to 0.67 mmol m -2 d-1 up the stream.
Surprisingly though benthic denitrification rate (NO3-+NO2- influx) varied from 0.08 to 0.41
mmol m-2 d-1 and did not show any trend along the salinity gradient, it showed a strong
correlation with water column NO3-+NO2- concentration. Though modest, build up of N 2O
and its subsequent consumption observed in all the anaerobic incubations suggests benthic
denitrification causing NO3-+NO2- influx. NH4+ comprised 91% of the DIN efflux at Betim
which progressively decreased to 2% at Ganjem. In contrast, 8% of DIN released at Betim
was in the form of NO3-+NO2- which progressively increased to 97% at Ganjem. Differences
in anaerobic NH4+ and aerobic DIN flux suggest that at Betim 38% of upward diffusing NH4+
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was lost in the coupled nitrification-denitrification within the sediment which reached a
minimum at Amona (24%) and increased further to 69% at Ganjem. Benthic nitrification rate
varied from 1.84 to 2.21 mmol m-2 d-1 from Betim to Ganjem with a minimum (0.98 mmol m2 -1
d ) at Amona and showed no correlation with salinity. Both NH4+ and PO43- effluxes
showed inverse correlation with salinity indicating the geochemical control of salinity on
their release. SiO44- was released at Betim and Amona at a rate of 2.4-3 mmol m-2 d-1 but
showed downward flux at Ganjem. Higher benthic release of DIN and PO43- towards
downstream implies that the estuary is more productive at the higher salinity end during
the premonsoon. Decrease in porewater NH4+ and PO43- towards Ganjem indicates the
effect of low salinity in controlling lower effluxes. Benthic denitrification can potentially
remove 14-100% of the riverine DIN input and downward PO43- fluxes indicate that the
adsorption and buffering capacity of the sediment can potentially remove 22-39% of the
riverine DIP from Betim to Ganjem during the premonsoon.
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BIOGEOCHEMICAL CYCLING IN MANDOVI AND ZUARI ESTUARIES, WEST
COAST OF INDIA
Hema Naik*, D. M. Shenoy, S. Kurian, S. W. A. Naqvi
1
CSIR-National Institute of Oceanography, Dona Paula –Goa, 403 004; [email protected]
Under SIBER-India programme, we have been monitoring the estuarine systems –
Mandovi and Zuari estuaries off Goa on a monthly basis since 2010. Both are well mixed
coastal plain monsoonal estuarine systems situated between latitude 15°25’ – 15°31’N and
longitude 73°45’ – 73°59’ E along the west coast of India. The physico-chemical conditions of
the estuaries are influenced by the fresh water runoff during the monsoon (JuneSeptember) and the tidal influx of coastal waters during the non-monsoon (October to
May). The maximum heating in the both surface and bottom waters takes place in the
upstream reaches of the estuaries. During premonsoon (Feb-May), the intrusion of salt
water in the estuaries is deep and is maximal in May upto a distance of 30 km from the
mouth. During the monsoon, the estuary is almost dominated by freshwater. The
freshwater dominance from upper reaches creates a strong stratification giving rise to salt
wedges at the mouth upto a distance of 1-4 km in the Mandovi Estuary and upto 5 - 10km in
the Zuari Estuary. The estuarine waters remain oxic and homogenous during most times of
the year. The dissolved oxygen concentrations are slightly higher in upstream reaches (~ 5
ml/L) as compared to the mouth (4-4.5 ml/L) indicating freshwater influence at the former.
The nutrient enrichment occurs at the upstream end as a result of riverine flow but at the
mouth the concentrations decrease drastically due to the increased uptake rates and mixing
with sea water which is oligotrophic during non-monsoon periods. With the onset of
monsoon during June – September, the water column gets enriched with nutrients such that
nitrate concentrations increase as much as 12 – 17µM and silicate concentrations reaching
upto 100µM within the entire estuary. As the precipitation decreases in August, water
column at the mouth of the estuary gets highly stratified with O2 - depletion (lowest
concentrations observed in August ~3µM and 10µM in Mandovi and Zuari respectively) in
bottom depths resulting from decomposition of organic matter.
The nutrient-rich estuary now shows reduced concentrations of nutrients at the
mouth. This process could be a regional phenomenon or could be the flow of low
oxygenated upwelled water mass from the inner shelf region that is entering the estuaries.
There is evidence of upwelled waters intruding in Mandovi and Zuari in 1972 but the O2
values recorded were not as low as in our observations. Also we have not noticed the
hydrogen sulphide at estuarine mouth as it happens at the inner shelf station of time-series
site (CATS) located 10kms away from here. These waters show some accumulation of N2O
(upto 100nM); build-up seen upto a distance of 10km from mouth of the estuary which
could be supported by denitrification process. However, the low oxygenated water mass did
not show accumulation of CH4 indicating that the water column do not turn anoxic. Based
on available information it is known that the Indian estuaries along the east coast are also
experiencing O2 depletion which gets severe during peak monsoon period but there is no
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evidence of denitrification in these waters implying the estuaries located along the two
margins of India, eastern and western, experience different biogeochemical settings. The
present study attempts to explain the biogeochemical variations within both the estuaries
over a period of one full annual cycle.
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VARIATION OF DIMETHYLSULPHIDE AND ASSOCIATED COMPOUNDS IN THE
MANDOVI AND ZUARI ESTUARY
Kausar Fatima M. Bepari, Damodar M. Shenoy*, M. Gauns, H. Naik and S.W.A. Naqvi
CSIR-National Institute of Oceanography, Goa, INDIA; [email protected]
Estuaries are complex systems which form an important link between the terrestrial
and the oceanic systems. The Mandovi-Zuari estuarine systems situated between 1515’N
to 1530’N and longitude 7345’E to 7406’E is one of the unique tropical estuarine systems
along the west coast of India. Under the SIBER-India programme dimethylsulphide (DMS),
total dimethylsulphoniopropionate (DMSP) and total dimethylsuphoxide (DMSO) were
measured in the surface and bottom waters along these estuarine systems during January
2011 to December 2012 with an aim to study their spatial and temporal variability. In
general higher concentrations of DMSP and DMS were observed near the mouth of the
estuaries with the lowest observed in the upper reaches of the estuary. In contrast, DMSO
concentrations in both the estuaries were observed even in the upper reaches of the
estuary with higher concentrations observed during the southwest monsoon season and
associated with low saline fresh water runoff suggesting a different source other than of
phytoplankton origin. In the Mandovi estuary, the DMS concentrations varied between
undetectable levels and 59.7 nM with the maximum observed at M3 station during the
southwest monsoon period, whereas the DMSP concentrations varied between 0.4 nM and
75 nM with the maximum observed at M1 station during the pre-monsoon period. In the
Zuari estuary, the DMS concentrations varied between undetectable levels and 57.8 nM
with the maximum observed at Z1 station during the pre-monsoon period, whereas the
DMSP concentrations varied between undetectable levels and 39.1 nM with the maximum
observed at Z1 station during the onset of the southwest monsoon. Both estuaries observed
higher concentrations of DMS and DMSP in 2012 in comparison to 2011. No correlation was
observed between chlorophyll and DMSP or DMS in both the estuaries, however a linear
relationship was observed with salinity supporting the osmoregulatory role of DMSP in
phytoplankton cells.
References:
Shenoy, D. M., & Patil, J. S. (2003). Temporal variations in dimethylsulphoniopropionate and
dimethyl sulphide in the Zuari estuary, Goa (India). Marine Environmental Research, 56(3),
387-402.
Shenoy, D. M., Sujith, K. B., Gauns, M. U., Patil, S., Sarkar, A., Naik, H., & Naqvi, S. W. A.
(2012). Production of dimethylsulphide during the seasonal anoxia off Goa.
Biogeochemistry, 110(1-3), 47-55.
Shenoy, D. M., & Kumar, M. D. (2007). Variability in abundance and fluxes of dimethyl
sulphide in the Indian Ocean. Biogeochemistry, 83(1-3), 277-292.
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IMPACT OF SEWAGE DISCHARGE ON THE WATER QUALITY OF VERSOVA
CREEK
Anirudh Ram*, B. R. Thorat, M. A. Rokade, D. Majithiya, A. Yadav, S. Salvi, V. Joshilkar, N.
Shinde, Jiyalal Ram. M. Jaiswar, S. N. Gajbhiye
CSIR-National Institute of Oceanography - Regional Centre, Mumbai; [email protected]
Versova Creek receives 4.40 x 105 m3/d sewage from point sources among which 2.0
x105 m3/d is released after aeration in the lagoon other 2.4 x10 5 m3 /d sewage is released
directly after screening. Apart from known point sources the creek receives sewage as well
industrial wastes from non-point sources of suburban Mumbai. The present study
represents the spatial and temporal variation of water quality and plankton characteristics
collected during 1991-2014 from Versova Creek to study the anthropogenic impacts on the
water quality of Versova Creek. The creek remains anoxic (DO<0.2 mg/l) during low tide
with high concentration of BOD (22 ±9.0 mg/l) and production of H 2S (27.7± 8.6 µmol/l)
even during monsoon period. As a result of organic matter oxidation PO43--P (21 ± 15
µmol/l) and NH4+-N (43.4± 35 µmol/l) are released in the water of Versova Creek. Factor
analysis indicated that ammonia and phosphate are having anthropogenic source into the
creek. Low concentrations of NO3--N and NO2--N and high concentrations of PO43--P, NH4+-N,
and BOD in this creek suggest sewage as the polluting source. Thus, though the sewage is
treated in aerated lagoons at Versova post 1992, the water quality has not improved
indicating that either the lagoons are inefficient in the removal of BOD or the sewage
release is far in excess the assimilative capacity of the creek. With DO falling to zero
sulphide is released, condition under which the fauna is severely impacted. DO replenish
and concentration of H2S decreases with the ingress of coastal water to the creek during
flood. Increased concentration of NO2--N (4.9,±3.2µmol/l ) and NO3--N (29.2,±20.7µmol/l)
were recorded during high tide as a result of oxidation of NH4+-N to NO3--N with NO2--N as
intermediate product. Appearance of bloom of toxic algae, Microcystis aeruginosa in recent
years indicates alarming condition in the region. During 1994, 2000 and 2009 enhanced
levels of average chl a of 10.4 mg m-3, 32.5 mg m-3 and 26.1 mg m-3 respectively may be due
to the high anthropogenic nutrient inflow to the creek. The result of present study indicates
that the condition of Versova Creek has not improved in recent years creating threat of
spreading hypoxia in the coastal water.
Nutrient analyses were undertaken by following the method of Strickland and Parsons
and concentration of pigments was determined following the Standard Methods (Strickland
and Parsons 1972).
32
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Factor Analysis
Low Tide
Component
Phosphate
Nitrite
Nitrate
Ammonia
DO
Salinity
pH
Eigen value
Cumu.
Variance
Total
Variance %
30
High Tide
1
-0.17
0.62
0.83
-0.52
0.63
0.04
0.71
3.07
2
0.85
-0.15
0.05
0.43
-0.29
-0.83
-0.46
1.11
43.92
59.80
43.92
15.88
Component
Phosphate
Nitrite
Nitrate
Ammonia
DO
Salinity
pH
Eigen value
Cumulative
Variance
Total Variance
%
1
-0.30
-0.03
0.31
-0.02
0.85
0.86
0.65
3.23
2
0.81
-0.29
0.06
0.90
-0.11
-0.11
-0.56
1.19
3
0.22
-0.88
-0.84
0.01
0.00
-0.18
-0.30
1.17
46.28
63.34
80.11
46.28
17.06
16.76
Chl a and Phaeo distribution 1992-2014
Nutrients
50.0
45.0
25
Chl a
40.0
mg/m3
15
10
30.0
25.0
20.0
15.0
10.0
5
5.0
HT
2014
2013
2011
2010
2009
2008
2007
2006
2004
Ammonia
2000
Nitrate
1998
Nitrite
1992
Phosphate
1996
0.0
0
1994
µM
Phaeo
35.0
20
Year
LT
References:
1. Strickland, J. D. H. and T. R. Parsons (1972): A Practical Handbook of Seawater Analysis.
2nd ed., Bull. Fish. Res. Bd. Can. No. 167, 310 pp.
33
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22-24 March 2015
METHANE EMISSIONS FROM THE SHELF WATERS OF SOUTHEASTERN
ARABIAN SEA
V.Sudheesh, G.V.M.Gupta* and M.Sudhakar
Centre for Marine Living Resources and Ecology, Ministry of Earth Sciences, Kendriya Bhavan, Kakkanad,
Cochin-682037, India; [email protected]
Greenhouse gases (GHGs) from human activities are the most significant triggers of
observed climate change since the mid-20th century. Among the most important GHGs,
methane accounts for 20% of “enhanced greenhouse effect” and has a greenhouse gas
potential of 25 times higher than that of carbon dioxide. Tropospheric methane has a
variety of global sources, of which more than one half are anthropogenic. Coastal areas such
as continental shelves, estuaries, deltas, fjords and lagoons can significantly contribute
methane to the atmosphere. But highly limited data base from these coastal regions
resulted in an uncertain magnitudes and variability of oceanic emissions of methane. In this
study, we attempted to fill this gap from the shelf waters of Cochin (10°N), southeastern
Arabian Sea through monthly observations made between April and December 2012. High
methane concentrations were recorded in the nearshore region (7-152 nM, avg. 42±36 nM)
which decreased towards mid-shelf (0-8.8 nM, avg. 2.4±2.3 nM) and outer shelf (0-8.2 nM,
avg. 2.6±2.6 nM). Methane distribution in the shelf waters has not been shown to
influenced by seasonal physical or biogeochemical forcings but affected largely by the
discharges from the adjoining eutrophic Cochin estuary (CE) which recorded very high
methane concentrations (309±233 nM) due to large scale anthropogenic perturbations. The
methane flux from the Cochin shelf varied between 0 and 720 µmole m -2 d-1 with an average
of 57±130 µmole m-2d-1. By extrapolating these fluxes linearly between southern tip of India
to north of Cochin (7-11°N), the methane fluxes from the southwestern shelf region is
computed at 0.007 Tg y-1. This represents 4-7% of the total Arabian Sea methane emission,
is significant.
34
OSICON-15
22-24 March 2015
BEHAVIOUR AND FATE OF TRACE ORGANIC CONTAMINANTS IN THE COCHIN
ESTUARINE SYSTEM (CES), INDIA: AN OVERVIEW
P.S. Akhil, C.H. Sujatha*
Cochin University of Science and Technology, Cochin-16, Kerala, INDIA; [email protected]
The study on sediment biogeochemistry is being considered as record of impact,
relying on the time integrative capacity of the sediment in the aquatic system. The
sediments themselves are also the warehouse of the contaminants that can impact directly
on the benthic ecosystem. Certain radionuclides and certain trace organic compounds (OCIs,
PCBs, and PAHs etc) have both a geochemical and environmental half-life from which they
can predict their persistence in the estuarine environment. Further, using a range of trace
contaminants provides an important and verifiable approach to ecosystem health
assessment. Therefore, their origin and fate in ecosystems cannot be understood without a
fair knowledge on biogeochemical cycles. Estuarine sediments act both as a short or long
term reservoir for many type of organic/inorganic contaminants (OCIs, PAHs, PCBs, trace
metals etc). Diffusion, advection, mixing and resuspension of the sediment will affect the
distribution of these trace contaminants in the estuarine niche. In this lacuna, a
comprehensive idea on these disciplines will contribute a major role for the assessment of
water quality and their management procedures in the aquatic system. Hence, the present
research work elucidates the spatial and vertical trend pattern of Organochlorine Insecticide
(OCI) residues in the sediments of CES. For this assignment, Fifteen persistent
organochlorine compounds (OCs) were quantitatively analysed in the 6 sediment core
samples and 17 surface sediment samples collected from specific sites of CES during
November 2009 and 2011. Among these contaminants, residual levels of HCH, Cyclodienes
and DDT were the dominant entities. According to the sediment quality guidelines (SQGs),
the higher concentration of these persistent toxicants were found in the CES was enough to
pose ecological risk to the bottom dwelling consumers. The main theme and objective of the
study is to account the contaminant levels, distribution pattern and other contributing
sources for assessing the environmental impact in the ecosystem. Moreover, the study
intend to explain a brief explanation on how the biogeochemical studies of surface and
sediment core profiles helps to describe the varying encapsulated biogenic compounds.
Besides, the generated inference would provide useful information on the changes in the
quality of the sediments from the past period.
35
SESSION-01
SESSION-01
OSICON-15
22-24 March 2015
INTER-SEASONAL OBSERVATIONS IN DMS (P) VARIABILITY IN TROPICAL
INTERTIDAL ESTUARINE ECOSYSTEM
Pandey Sunita Surendra, P. A. LokaBharathi*
CSIR - National Institute of Oceanography, Goa, India; [email protected]
Dimethylsulphide (DMS) and its precursor dimethylsulphoniopropionate (DMSP) are
climatically and biologically relevant sulphur compounds produced in the marine ecosystem.
Tropical estuaries are characterized by seasonal influence in hydrography and physicochemical variables. In this study, we elucidated the factors influencing DMS variability in the
intertidal zone of Dona Paula Bay with a hypothesis that tides wield their influence on DMSP
dynamics irrespective of the season. To meet our objective, we carried out time series
observations at 6 hour intervals synchronizing with tides during monsoon and non-monsoon
season along with relevant environmental variables. A significant seasonal pattern in
influence of tide on the abiotic and biotic factors involved in DMS (P) dynamics in tropical
estuarine bay sediment was found during dry season. Average DMSP and DMS
concentration was highest during monsoon ~ 252nM and 8 nM respectively, followed by
~60 nM and 4nM during post-monsoon. The lowest average was ~49 and 5 nM during premonsoon. During pre-monsoon season tides influenced both producers (17%) and utilizers
(13%) of DMSP. Tidal height also exhibited positive correlation with DMS concentration (r =
0.478, p<0.01). This inference was further corroborated by Principal component analysis
where tide featured as the most important variable in PC1 which yielded maximum
influence. The precursor DMSP correlated well with the abundance and biomass of
producers (phytoplankton and chl a), which in turn were influenced by nutrients during this
season. During monsoon, physico-chemical variables like light, salinity, and phosphate were
related to DMS. Abiotic factors like nitrate, silicate showed positive correlation with tidal
amplitude. Also, the utilizers of DMSP (CFU) linked positively with the DMS content in the
sediment. The association of DMSP with the phytoplankton continued during monsoon.
During post-monsoon, the interactions were similar to those during monsoon where light,
salinity, chl a and phosphate were linked to DMS. DMSP related only to chl a and not to
phytoplankton. PCA also showed that chemical factors like pH, DO, and nitrate influenced
the producers and utilizers during monsoon. Our results indicate that 1) intertidal
sediments are significant sources of DMS (P), 2) direct tidal influence on the DMS (P)
dynamics and source and sink of DMSP was masked by the combined influence of physicochemical factors during monsoon in the intertidal sediments.
36
SESSION-01
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22-24 March 2015
800.0
700.0
600.0
500.0
400.0
300.0
200.0
100.0
0.0
DMSP
25.0
DMS
15.0
10.0
5.0
Pre-monsoon
Monsoon Post-monsoon Pre-monsoon
December '11
November '11
October '11
September '11
August '11
July '11
June '11
May '11
April '11
March '11
February '11
January '11
December '10
November '10
October '10
September '10
August'10
June '10
July '10
May '10
0.0
MonsoonPost monsoon
Figure 1: Seasonal variability in DMS, DMSP in sediment of Dona Paula Bay
37
DMS (nM)
20.0
March '10
April '10
DMSP (nM)
SESSION-01
OSICON-15
22-24 March 2015
MEASUREMENT OF NITROGEN FIXATION RATES ALONG THE SOUTHWEST
COAST OF INDIA
Ayaz Ahmed*, Mangesh Gauns, Pratirupa Bardhan, Damodar Shenoy, Hema Naik, Siby
Kurian, Anil Kiran Pratihary and SWA Naqvi.
CSIR-National Institute of oceanography; Dona Paula Goa-403004; [email protected]
Nitrogen (N2) fixation is an important process by which new nitrogen is introduced
back to the oceanic system. We report here nitrogen fixation rates measured, south of 15 oN
(Fig. 1), during February 2013 in the upper euphotic water column from the eastern Arabian
Sea using 15N2 tracer gas. The N2 fixation rates varied between 0.4 and 144 µmolN/m3/d.
The higher rates were consistent with low δ15N of particulate organic matter reflecting Nfixation. The high rates (144.3 µMN/m3/d) found in the low nitrate region correspond to the
early phase of Trichodesmium bloom where as the moderate rates (9.7µMN/m3/d)
corresponded with the senescence phase. Lower N2 fixation rate (< 1 µmolN/m3/D) was
observed at stations devoid of any Trichodesmium. Phosphate concentration seemed to
drive the nitrogen fixation at lower levels of nitrate (<1 µM). Carbon fixation rates measured
at a few stations using 14C technique showed rates between 0.07 and 12.8 mg C/m3/d. The
present N2 fixation rates measured with modified technique is the first study of its kind from
the region and has given important insight at the rate of nitrogen input to the total nitrogen
pool of the area.
Fig.1 Map showing station locations in Arabian Sea
38
OSICON-15
22-24 March 2015
CONCENTRATION OF TRACE METALS AND THEIR COVARIANCE WITH
CARBON, NITROGEN AND SULPHUR IN ANOXIC ENVIRONMENT OF VERAVAL
HARBOUR
Divya Majithiya, Ajay Yadav, Anirudh Ram*, Shailesh Salvi, Archana Kamble
Regional Centre, CSIR-National Institute of Oceanography, Mumbai, India; [email protected]
Veraval located (20o53’N 70o26’E) on north-west coast of India is home to many
textiles, chemicals and food processing industries and is the largest fishing harbour in Asia.
The Veraval Harbour receives anthropogenic wastes from fish processing industries and
sewage from Veraval City. The harbour has the stagnant water condition, due to the lack of
turbulence, wind action and tidal effect in and around the jetty because of the abrupt
designing of it, making dilution an impossible task for tides coming towards the jetty. Due to
organic load discharge and restricted flushing, the water of Veraval Harbour remains anoxic
irrespective of tides (NIO,TR, 2014) resulting the surface sediment also anoxic. The present
work aims to study the effect of waste water discharge on the sediment quality ofharbour
with special reference to the metal accumulation and their behaviour in the anoxic
sediment. Two short sediment cores, (core 1, core 2) were collected and analysed for heavy
metals such as Fe, Mn, Cr, Cu, Zn, Pb, Hg, and Cd from the Veraval Harbour. Sediment
carbon and nitrogen ratio was examined to determine the source of organic matter.Analysis
of sulphur was done to find out its control on heavy metals in anoxic sediment. Overlying
bottom water of harbour was analysed for dissolved oxygen, hydrogen sulfide and dissolved
metals to understand their role on sediment chemistry. A 63cm sediment core (Station-3)
collected at the water depth of 30m from 10 km distance off Veraval Harbour was studied to
find the baseline data and for calculating enrichment factor in harbour sediment.
Irrespective of tide, harbour water was found to be anoxic (DO <0.2 mg/l) with high
concentration of ammonia (av. 459±21 µmol/l) and hydrogen sulphide (av. 73±2.5 µmol/l) at
core 1 and core 2. In the harbour sediment core 1, geoaccumulation indices showed that Cd
was extremely enriched (EF=147±49) followed by Hg (EF=5.3±1.4), Pb (EF=5.1±0.7), Cr
(EF=5.0±0.96), Zn (EF=4.51±0.7) and Cu (EF=2.79±0.5). In core 2 enrichment was Cd
(EF=13.2±7.5), Pb (EF=3.9±2.6), and Hg (EF=3.0±1.4). Fe and Mn concentrations were less
than the background concentrations in the harbour sediment cores at both the stations.
High concentration of Mn and Fe in overlying water indicates that under reduced conditions
prevailing in the harbour, the sediment Fe-Mn oxides were reduced to Fe (II) and Mn (II) and
diagenetically mobilized upwards in the sediment. The reduced Fe (II) and Mn (II) diffused
upwards through interstitial water. As the overlying water was also anoxic, the mobilized Fe
and Mn escaped in the water column instead of precipitating at the water sediment
interface, increasing the concentration of dissolved Fe (41.0 ± 0.4 µg/l) &Mn (40.9 ±0.7 µg/l)
in water. Low concentration of Cd (0.2 ± 0.01 µg/l), Pb (1.0 ± 0.05 µg/l) and Hg (0.2 ± 0.01
µg/l)in water and theirstrong positive correlation with total organic carbon (r=0.85, 0.91,
0.78 at p<0.001) and sulphur (r=0.69, 0.85 at p<0.001, r=0.51 at p<0.05) respectively in the
sediment coresindicates that these metals are controlled by carbon and sulphur and not
mobilized diagenetically even in the anoxic conditions [Sappal, et al., 2014]. Elements like
39
SESSION-01
SESSION-01
OSICON-15
22-24 March 2015
Cu, Zn, Cd and Hg are higher in core 1 sediment compare to core 2. Similarly TOC and TN are
also higher in core 1. Core 1 was taken from upper most part of the harbour, which is in the
vicinity of discharge of industrial effluent. It is likely that the above elements accumulate
near the source before moving to the downstream (Ram et al. 2009). The anoxic overlying
bottom waters with high dissolved sulfides and strong positive correlation of Cu, Zn, Cd, Pb
and Hg with total sulphur in the sediment cores indicated sulphur as the controlling factor
scavenging the anthropogenic Cu, Zn, Cd, Pb and Hg.C/N ratio of harbour sediments at
station-1 was (13±1.7) and at station-2 was (24±3) higher than the normal marine planktonic
sediments [Bayraktarov and Wild, 2014] suggesting an increased contribution of terrestrial
carbon in the harbour sediments.
Our study indicates that the sediment of Veraval Harbour is contaminated with metals
such as Cu, Zn, Cd, Pb and Hg. Due to anoxic condition in the harbour, Fe, Mn and Zn are
diagenetically mobilized and remain in high concentration in the dissolved form. The
present study proves that concentration of metals such as Cd, Pb and Hgare mainly
controlled by carbon and sulphur and not by Fe-Mn oxides even in the anoxic conditions.
References:
Bayraktarov, E. and Wild, C. (2014) Spatio-temporal variability of sedimentary organic
mattersupply and recycling processes in coral reefs of Tayrona National Natural Park,
Colombian Caribbean. Biogeosciences, 11, 2977–2990, 2014.
NIO,(2014) Marine EIA and Site Selection for the Seawater Intake and Outfall in Arabian Sea
off Veraval for Reverse Osmosis (RO) Reject from Desalination Plant of Indian Rayon.
NIO/SP-04/2014, pp. 1-127.
Ram, A., Rokade, M. A., Zingde, M. D. And Boreole, D. V. (2009) Post-depositional memory
record of mercury in sediment near the effluent disposal site of a chlor-alkali plant in Thane
Creek-Mumbai Harbour, India. Environmental Technology 30, 765-783.
Sappal, S. M.; Ramanathan, A. L.; Ranjan, R. K. and Singh, G.(2014) Sedimentary
geochemistry of Chorao Island, Mandovi mangrove estuarine complex, Goa.Indian Journal of
Geo-Marine Sciences, 43 (6), 1085-1094.
40
OSICON-15
22-24 March 2015
PHYTOPLANKTON–ZOOPLANKTON DYNAMICS IN COASTAL WATERS OF
CENTRAL WEST COAST OF INDIA
Mangesh Gauns, Anil Pratihary, D M Shenoy, Siby Kurian, H Naik and S.W.A. Naqvi
Biological productivity in the Arabian Sea is regulated mainly by nutrient inputs from
subsurface waters via upwelling in summer and convective mixing in winter resulting in
widespread phytoplankton blooms during both summer and winter. This, in turn, supports
high export flux of organic matter to the deep sea, which contributes to the development of
one of the thickest and most intense oxygen minimum zones of the world's oceans. In
contrast to the perennial OMZs found in the open ocean areas of the northern Indian
Ocean, severe oxygen deficiency also occurs during summer upwelling along the western
continental shelf of India, covering an area of 180,000 km 2. The onset of the southwest
monsoon (SWM) in June marks the beginning of upwelling along the SW coast of India
which propagates northward and persists until October. Upwelling brings up subsurface
water having low dissolved oxygen content over the shelf. The upwelled water is, however
capped by a thin low-salinity layer, which is formed as a result of intense rainfall runoff in
the coastal zone. Degradation of organic matter in the relatively stagnated upwelled water
quickly removes the residual oxygen below the shallow pycnocline.
Systematic studies carried out at the Candolim Time Series (CaTS) site located central
west coast of India (off- Goa) have shown regular occurrence of hypoxia following the
southwest monsoon (September-October period). The onset of oxygen-deficient conditions
profoundly influences the dynamics of both phyto- and zooplankton. While microplakton
(mostly diatoms but also dinoflagellates) constitute the major part of the phytoplankton
biomass in oxic waters; pico-autotrophs, and to a smaller extent, pennate diatoms were
found to be predominant in oxygen deficient waters. The zooplankton biomass was
generally higher in oxic waters as compared to oxygen-deficient waters. Among various
zooplankton, only a few forms observed to survive at low concentrations of oxygen (< 1 ml l 1
). The mechanism of survival in these organisms under very low oxygen environments is not
known and needs to be investigated. This study also highlights long-term changes in
zooplankton and phytoplankton abundance and floristic composition at the coastal time
series site (CaTS).
41
SESSION-01
SESSION-01
OSICON-15
22-24 March 2015
GLOBAL SEAWATER DMS CLIMATOLOGY: COMPARISON & UPDATE
Smrati Gupta*, Anoop S. Mahajan
Centre for Climate Change Research, IITM, Pune; [email protected]
Dimethyl sulfide (DMS), produced by oceanic phytoplankton, being the most abundant
source of natural sulfur over the marine environment plays an important role in influencing
cloud microphysics, aerosol radiative forcing and hence the Earth’s radiation budget (as
initially suggested by the CLAW hypothesis). Seawater DMS climatology is used by models to
estimate the atmospheric DMS distribution and hence the resultant sulfur entities in
atmosphere which affect cloud properties and radiation. Classical DMS climatology used in
modelling studies is more than a decade old (Kettle and Andreae, 2000) referred to as K00,
and was made with a few DMS data points. Since then, oceanic DMS measurements have
increased and also measurement techniques have improved. A relatively newer DMS
database is available in the shape of a recently published climatology (Lana et al., 2011)
referred to as L10. The aim of this project work was to study the impacts of using the newer
DMS climatology (L10) and validation of the model simulations with available observations.
Model used is state-of-the-art GCM ECHAM-HAMMOZ aerosol chemistry model. Results
showed the use of updated L10 climatology over prevailing K00 results in decrease in the
total aerosol radiative forcing, which corresponds to the 20% cooling attributed to DMS
climatology chosen (Figure 1). Comparison of model simulations with the available
observations of atmospheric DMS and total sulfate also showed better correlation with the
L10 climatology. Figure 2 shows the comparison between the observed atmospheric DMS
climatology at Amsterdam Island, Southern Indian Ocean (1990-1999) and the modeled
DMS at the surface using the K00 and L10 climatologies. Using the L10 climatology, the
correlation coefficient value shows a strong improvement (R=0.83, P=0.001) as compared to
the K00 climatology (R=0.45, P=0.15). For compiled discrete observations from all over the
world, the L10 climatology shows a modest improvement in describing the atmospheric
DMS as compared to the K00 climatology (Figure 3); R=0.48 for L10 as compared to 0.44 for
K00. These results stress the necessity of using the latest updated climatology in modelling
studies. Although better correlated with the observations, the L10 was found to
overestimate DMS for the higher DMS concentrations. This was the motivation to update
the L10 with recent data (Malaspina expedition 2010) as L10 was constructed using the
seawater DMS data up to the year 2010. These helped lower the DMS concentrations to a
certain extent and might help explain the positive bias in the model for atmospheric DMS.
Furthermore, we observed some immediate changes in the annual DMS characteristics of
few of the Longhurst’s biogeographic provinces attributed to the presence of increased
number of data points in the regions influenced by DMS data obtained in Malaspina
expedition. Further groundwork to develop subsequent climatologies at IITM through
inclusion of a new high frequency data was also done, which is directed to create a new
updated climatology taking into account the availability of high frequency data now-a-days.
This work will lead to further updates, which should help reduce the present discrepancies
between model simulations and observations.
42
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22-24 March 2015
L10-K00
Aerosol Radiative Forcing at TOA (W m-2)
Figure 1 : Difference between the model output using two climatologies (L10-K00) for ARF
Figure 2: Comparison between the observed atmospheric DMS
climatology at Amsterdam Island, Indian Ocean (1990-99) and the
modeled DMS at the surface using the K00 and L10 climatologies
Figure 3: Correlation between the observed and modeled
DMS using the K00 and L10 seawater DMS climatologies.
References:
Charlson, R. J., Lovelock, J. E., Andreae, M. O., & Warren, S. G. (1987). Oceanic
phytoplankton, atmospheric sulphur, cloud albedo and climate. Nature, 326(16), 655–661.
Kettle, A. J., & Andreae, M. O. (2000). Flux of dimethylsulfide from the oceans : A
comparison of updated datasets and flux models. Journal of Geophysical Research,
105(D22), 26793–26808.
Kettle, A. J., Andreae, M. O., Amouroux, D., Bates, T. S., Berresheim, H., B, H., Uher, G.
(1999). A global database of sea surface dimethylsulfide ( DMS ) measurements and a
procedure to predict sea surface DMS as a function of latitude , longitude , and month.
Global Biogeochemical Cycles, 13(2), 399–444.
Lana, a., Bell, T. G., Simó, R., Vallina, S. M., Ballabrera-Poy, J., Kettle, a. J., Liss, P. S. (2011).
An updated climatology of surface dimethlysulfide concentrations and emission fluxes in the
global ocean. Global Biogeochemical Cycles, 25(1), n/a–n/a. doi:10.1029/2010GB003850
43
SESSION-01
SESSION-01
OSICON-15
22-24 March 2015
CARBON DIOXIDE EMISSIONS FROM A TROPICAL ESTUARY LOCATED ALONG
THE WEST COAST OF INDIA- ZUARI ESTUARY
Rashith P*, H. Naik, D. M. Shenoy and S.W. A. Naqvi
The Carbon dioxide species such as TCO2 and Alkalinity were measured in Zuari
estuary, a tropical estuary under the influence of strong monsoonal discharges. Water
samples were collected from 7 stations during 2011. The partial pressure of carbon dioxide
(pCO2) and pH were derived using measured TCO2 and alkalinity concentrations. While TCO2
and alkalinity concentrations were lower in the upper reaches of the estuary, averaging to
290.22 µmoles/kg and 407 µmoles/kg respectively, the concentrations were maximal at the
seawater end, averaging to 1934.4 µmoles/kg and 2112 µmoles/kg respectively, indicating
typical oceanic waters at the latter. The two CO2 species had strong correlation with salinity
(0-35) and behaved conservatively during the estuarine mixing. The pCO2 displayed strong
temporal and spatial variations within the estuary and showed inverse relationship with
salinity. The highest pCO2 concentrations were recorded in the early estuarine mixing (>
2000 µatm at salinity ~18). The ~3 times higher concentration (average pCO2~1244 µatm) as
compared to atmospheric (391.8 ppm) concentrations suggests that the estuary acts as a
source of CO2 to the atmosphere. The quality of organic matter brought in by the river and
rate of respiration could play a major role in sustaining these high values round the year.
The higher pCO2 effluxes to the atmosphere, with higher fluxes recorded during monsoon
which is influenced by stronger winds as compared to non-monsoon periods. The sea-air
fluxes of CO2 from the estuary ranges between 4.19 – 8.85 mM C m-2d-1 (Av. F = 6.52 mM C
m-2 d-1) which is found to be lower than that of the mean CO2 fluxes from the Indian
estuaries (27 mM C m-2 d-1) , which is even lower than that of polluted European estuaries
(Av. F= 170 mM C m-2d-1) suggesting lower flushing time of water in the estuary which
provides lesser time for the microbial degradation of the supplied organic matter.
44
OSICON-15
22-24 March 2015
INDIAN OCEAN VARIABILITY &
INDIAN MONSOON
SESSION - 02
45
SESSION-02
INDIAN OCEAN VARIABILITY & INDIAN MONSOON
SESSION-01
OSICON-15
22-24 March 2015
46
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22-24 March 2015
ROLE OF NINGALOO NINO/NINA IN ALTERING THE BIOLOGICAL ACTIVITY IN
SOUTHERN SUB TROPICAL INDIAN OCEAN
Sandeep.N1, K. Ashok1,2, Swapna.P1*, Aparna.K1
1
Centre for Climate change Research (CCCR), IITM, Pune; [email protected]
2
University of Hyderabad, Hyderabad, India
Using both Observations and Long Term Simulation of an ocean-biogeochemical
coupled model, we investigate the biogeochemical response of both Ningaloo Nino (Nina)
events, a climate mode associated with positive (negative) sea surface temperature (SST)
anomalies off the west coast of Australia in southern subtropical Indian Ocean. This recently
identified phenomenon effects precipitation over the western coast of Australia and thus
the agriculture. The interannual variability of this phenomenon effects the productivity in
this area. This paper provides an insight over the fluctuations in the productivity(using
chlorophyll as proxy) during Ningaloo Nino (Nina). Our Model is able to reasonably simulate
the characteristics of the biological variables in a way comparable to observations. During
the developing period of Ningaloo Nino (Nina), an anomalous low (high) chlorophyll appears
near the South West Australian Coast occuring concurrently with high (low) SST. The
difference in the spatiotemporal response of chlorophyll for the two events is due to the
southward advection of the meridional upper ocean current (Leeuwin current), which plays
a major role in productivity along the Australian Coast.
47
SESSION-02
SESSION-02
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22-24 March 2015
ROLE OF INDIAN OCEAN SST IN MODULATING ONSET AND PROGRESSION OF
ISM IN THE SUCCESSIVE YEARS OF 2013 AND 2014
Ramesh Kumar Yadav* and Bhupendra Bahadur Singh
Indian Institute of Tropical Meteorology, Pashan, Pune; E-mail: [email protected]
It is well known that the Indian summer monsoons of 2013 and 2014 had contrasting
onset and progression phases. The onset was timely and the progression of 2013 monsoon
was the fastest in the last 70 years, whereas 2014 had a delayed onset and a very lethargic
progression phase compared to 2013. The monthly rainfall of June, in 2013 being +34%
whereas in 2014 it was -43% of its long-period average. In this study, we observed that the
tropical Indian Ocean was much warmer and the warm-pool of Indonesia was much cooler
in 2014 than in 2013 in the month of May, a month ahead of the commencement of ISM.
The sub-tropical westerly jet (STJ) over south Indian Ocean was much stronger in 2013 than
in 2014. The warm (cool) SST anomaly over warm-pool region had caused the positive
(negative) 200-hPa geopotential anomaly over tropical Indian Ocean in the year 2013 (2014)
which has strengthened (weakened) the STJ over south Indian Ocean due to the
consequence of thermal wind balance. This created positive (negative) pressure anomaly
over Mascarene High and hence early (delayed) onset and fast (lethargic) progression of ISM
in the year 2013 (2014).
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22-24 March 2015
OBSERVATIONAL EVIDENCE OF MIXED ROSSBY GRAVITY WAVES AT THE
CENTRAL EQUATORIAL INDIAN OCEAN
P.M. Muraleedharan¹*, S. Prasanna Kumar¹, K. Mohanakumar2, S. Sijikumar3,
K.U.Sivakumar¹, Teesha Mathew¹
¹CSIR-National Institute of Oceanography, Goa; [email protected]
Department of Atmospheric Sciences, Cochin University of Science and Technology, Kochi, India
3
Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram, India
2
Six hourly soundings (GPS sonde) were carried out at the central equatorial Indian
Ocean (80º–83º E) during 25th September to 10th October 2011 under the CINDY2011
(Cooperative Indian Ocean Experiment on Intra-seasonal variability in Year 2011) field
campaign. One degree interval soundings were also taken along a meridional section at 83º
E from 5º N to 5º S during 12 - 20 October 2011 to supplement the time series data. Relative
humidity (RH) and meridional wind component exhibit downward propagation of air mass in
bands of high and low RH associated with northerly and southerly winds respectively. Low
(20-100 day) and high (2-10 day) frequency band pass filtered OLR data (NOAA interpolated
OLR) revealed the presence of Madden and Julian Oscillation (MJO) with 20-40 day
periodicity, and weak mixed Rossby Gravity (MRG) waves with 4-5 day periodicity. Eastward
(westward) propagating MJO (MRG wave) with wave numbers 3 – 4 (4 – 5), amplitudes of
anomaly 1.1 to 1.2 Wm-2 (1.8 Wm-2) were observed. The asymmetric bifurcation of warm
surface water by the subsurface cold water off Sumatra generate asymmetric convective
regimes in the vicinity of the equator probably triggered convection with periodicity similar
to MRG waves. The intermittent surface convection associated is believed to be responsible
for the ascending moisture to the middle troposphere prior to the initiation of MJO. The
moisture pumped to the middle troposphere makes the layer convectively more unstable
leading to the state of deep convection, a situation conducive for the MJO initiation
processes.
49
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SESSION-02
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22-24 March 2015
PRECIPITATION EXTREMES DURING SOUTHWEST MONSOON AND ITS
CONNECTION WITH INDIAN OCEAN DIPOLE
J.V. Revadekar1*, H. Varikoden1
1
Centre for Climate Change Research, Indian Institute of Tropical Meteorology, Pune ; [email protected]
The Indian Summer Monsoon rainfall (ISMR) has a profound impact on India’s socioeconomic growth. It occurs over the Indian region for four months from June to September
(JJAS). It significantly varies temporally and spatially over the region. Indian Summer
Monsoon is a fully coupled land–atmosphere-ocean system and it is linked with the ocean
variability. It is well known that the interannual variability (IAV) of ISMR is linked with El
Nino-Southern Oscillation (ENSO). Past studies also identified influence of the IOD which is
occurring in the tropical Indian Ocean on the IAV of the ISMR. However it is less known
about their impact on regional precipitation extremes.
In view of the above, regional features of summer monsoon rainfall extremes are
explored statistically in relation to IOD and ENSO. During positive IOD, increase in heavy
precipitation extremes is found over Indian region. Decrease in frequency of precipitation
extremes is found in negative phase and during increase in SSTs over Nino region.
50
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22-24 March 2015
TROPICAL INDIAN OCEAN SIMULATION USING NEMO-AGRIF
Umesh Kumar Singh1*, Suneet Dwivedi2, Lokesh Kumar Pandey2
1
K Banerjee Centre of Atmospheric and Ocean Studies, University of Allahabad, Allahabad;
[email protected]
2
M N Saha Centre of Space Studies, University of Allahabad, Allahabad, UP 211002, INDIA
An ocean circulation model NEMO is customized to run globally with the sea-ice
package at a horizontal resolution of 1 degree (362 x 292 grids) and with a nested (refined)
version over tropical Indian Ocean [15°S-25°N; 65°E-100°E] with a horizontal eddypermitting resolution of 1/4 degree (152 x 292 grids). The refinement is made using the
AGRIF (Adaptive Grid Refinement In Fortran) two-way grid-nesting tool. Both the versions
are integrated simultaneously with the previous one providing the boundary conditions for
the later. The model uses the tripolar ORCA grid and involves hydrostatic and Boussinesq
approximations. It uses 46 levels in the vertical with highest resolution of 5 m near the
surface and then slowly increasing at depth. The model is forced with Coordinated Ocean
Sea-Ice Reference Experiment version 2 (CORE II) air-sea forcings, namely, 6-hourly zonal
and meridional wind, humidity, radiation, air temperature, daily precipitation, and monthly
runoff. The model is integrated for 14 years (1994-2007) including 2 years of spin-up run. A
comparison with the observation shows that the model is able to realistically simulate the
surface as well as sub-surface structure of temperature, salinity, and velocity over the
tropical Indian Ocean.
51
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SESSION-02
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22-24 March 2015
IMAPCT OF INDIAN OCEAN VARIABILTY ON INDIAN SUMMER MONSOON
RAINFALL DURING RECENT YEARS
Sanjo Jose V1*, E. K. Kurien2, Athira P. Ratnakaran1, Binsiya T. K.1
1
Academy of Climate Change Education and Research (ACCER), K.A.U., Thrissur; [email protected]
2
Special Officer, ACCER, K.A.U, Thrissur
Indian Ocean Dipole mode (IOD) impacts, many surrounding regions of the Indian
Ocean. The western pole of the IOD has importance in modulating the rainfall over
northwest regions of India also in weakening the relationship between ENSO and Indian
summer monsoon rainfall (ISMR). The impact of IOD on ISMR during recent years (19772013) has been examined in this study.
The climatological distribution of ISMR shows maxima over western side of Western
Ghats. There is also a considerable rainfall of about 17mm/day seen over north-eastern
regions of India. The year to year variation of normalized monsoon rainfall anomalies and
IOD Mode Index (IODMI) during June, July, August and September (JJAS) shows that the
positive IOD years 1961, 1963, 1967, 1976, 1983, 1994, and 2007 are associated with
surplus rainfall. The correlation between normalized IODMI and rainfall anomalies is
negative during the two decades before 1990s and there is a positive correlation seen
during two decades after 1990s.
The seasonal characteristics of climatological mean variables (SST, wind, and rainfall)
were examined for January, May, July and October over southern Asia. The surface wind
changes its direction and precipitation zone shifts with the corresponding changes in the
warm SST region. This seasonal movement of these climatological variables has a significant
impact on the IOD mode variability.
The spatial correlation of the IODMI and ISMR anomalies indicates that the IODMI
positively influences the ISMR over the plains of monsoon trough region and also over some
parts of the north-eastern India during the last four decades. It has a negative influence over
the south-western parts of India.
Further study has been carried out to know the impact of IODMI on ISMR during the
three decades (1980-1989, 1990-1999, and 2000-2009) individually. During 1980-1989,
significant positive correlation shows over the plains of Bihar, West-Bengal and Orissa. The
correlation is negative over North-west central India, Maharashtra and northern Karnataka.
But when moving to 1990-1999 the positive correlation extends to north-west India and
north-eastern India. During the last decade (2000-2009), positive correlation is seen over
north-west central India and Maharashtra, but over North-eastern India, Bihar and West
Bengal, there is a significant negative correlation.
References:
Ashok, K. (2007), Nat Hazards, On the impacts of ENSO and Indian Ocean dipole events on
sub-regional Indian summer monsoon rainfall, 42, 273-285.
Krishnamurthy, V. (2003), Q. J. R. Meteorol. Soc., variability of the Indian Ocean: Relation to
monsoon and ENSO, 129, pp, 1623-1646.
52
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22-24 March 2015
POSSIBLE ROLE OF INDIAN OCEAN IN THE BIENNIAL TRANSITION OF INDIAN
SUMMER MONSOON IN OBSERVATION AND CMIP5 SIMULATIONS
Prasanth A Pillai1*, A. K Sahai1
1
Indian Institute of Tropical Meteorology; Pune, India; [email protected]
The biennial oscillation is a prominent component of interannual variation in the
Indian summer monsoon (ISM). This biennial variability forms the part of tropospheric
biennial oscillation (TBO) which includes both ISM and Australian summer monsoon (ASM)
along with air-sea interaction over the tropical Indian and Pacific oceans. Observations
indicate that the in-phase transition from ISM to ASM and out-of phase transition from ASM
to ISM occurs in both the presence and absence of El Nino- Southern oscillation (ENSO) in
the Pacific. The ENSO in the pacific maintains same phase through boreal summer and
winter and controls the in-phase ISM to ASM transition. In absence of ENSO, the ISM leads
the Indian Ocean SST anomalies and the SST anomalies can induce an in-phase ISM to ASM
transition. Thus apart from ENSO, ISM-Indian Ocean interaction also can induce ISM-ASM inphase transition. Meanwhile, the out-of- phase ASM-ISM transition in presence of ENSO will
depend on the phase of ENSO. Direct ENSO forcing is important when ENSO changes its
phase in boreal spring, which can cause out-of phase ASM-ISM transition. At the same time,
if ENSO maintains its same phase to next summer, the air-sea interaction in the Indian
Ocean plays major role on out-of phase transition. This air-sea interaction process in the
Indian Ocean can contribute to biennial transition of the ISM in absence of ENS also. We
have analyzed these observational evidences in century long ensemble simulations of
selected coupled models from Coupled Model Inter comparison Project 5 (CMIP5). The most
of the models show in phase ISM-to- ASM transition properly in presence of ENSO. At the
same time the out-of phase transition from ASM-ISM is not captured by many of the
models. Similarly the biennial transition in absence of ENSO is also not properly simulated
by models. Thus the present study put forward possible causes for the failure of the models
in capturing TBO transitions; (1) The models may be more depend on the ENSO for the interannual variability, (2) The long seasonal cycle of ENSO may be the reason for the absence of
out-of phase ASM to ISM transition even after the successful in phase ISM-ASM transition.
(3) The ISM- Indian Ocean SST interaction is not strong enough to cause biennial transition
of ISM-ASM system. Thus the study underlines the need of accurate simulation of Indian
Ocean along with ENSO cycle for the ISM-ASM transitions.
53
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SESSION-02
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22-24 March 2015
ROLE OF INDIAN OCEANS IN CLIMATE OF WEST COAST OF INDIA
P.K. Murumkar1, H. Varikoden1, S.A. Ahmed2, J.V. Revadekar1*
1
Centre for Climate Change Research, Indian Institute of Tropical Meteorology, Pune-411008;
[email protected]
2
Department of Geology, Central University of Karnataka, Gulbarga-585 311
The Western Ghats are a mountain range that runs almost parallel to the western
coast of the Indian peninsula. During the summer monsoon season between June and
September, the Western Ghats acts as a barrier to the moisture laden clouds. The heavy,
eastward-moving rain-bearing clouds are forced to rise and in the process deposit most of
their rain on the windward side. Rainfall in this region averages 3,000–4,000 mm with
localised extremes. The eastern region of the Western Ghats lies in the rain shadow. Using
daily station data, Revadekar et al., (2013) have shown that high altitude stations in
peninsular India exhibit positive trends in surface temperature extremes.
In the tropical regions the interannual to decadal modes of climate variability are
coupled ocean-atmosphere modes. In this study therefore, an attempt is made to analyse
variability in temperature-rainfall over west coast and its relation with SSTs. Both summer
and winter monsoon climate over west coast show link with Indian Ocean Dipole (IOD).
Minimum temperature show strong link compared to maximum temperature.
References:
Revadekar J.V., Hameed S., Collins D., Manton M., Sheikh M., Borgaonkar H. P., Kothawale
D. R., Adnan M., Ahmed A. U., Ashraf J., Baidya S., Islam N., Jayasinghearachchi D., Manzoor
N., Premalal K. H., Shreshta M.L.(2013), Impact of altitude and latitude on changes in
temperature extremes over South Asia during 1971–2000, International Journal of
Climatology, 33, 199-209
54
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22-24 March 2015
NEAR-SURFACE STRATIFICATION AND SUBMESOSCALE FRONTS IN THE
NORTH BAY OF BENGAL IN AUGUST-SEPTEMBER 2014
J. Sree Lekha1*, S. Shiva Prasad2, M. Ravichandran2, D. Sengupta1
1
CAOS, Indian Institute of Science, Bangalore *[email protected]
Indian National Center for Ocean Information Services (INCOIS), Hyderabad
2
A shallow layer of freshwater with a strong halocline underneath (Gopalakrishna 2002,
Sengupta 2006) influences air-sea interaction (Sengupta 2008) and bio-geochemistry in the
north Bay of Bengal. In this study, we use 1800 kilometers (Figure 1) of underwayConductivity-Temperature-Depth (uCTD) data, collected from the ORV Sagar Nidhi during
22 August-4 September 2014, to understand the physical processes that maintain the
shallow stratification. At ship speeds of 4-5 knots, the horizontal resolution is of order 1 km,
and vertical resolution is 1m. These are the first observations from the Bay of Bengal with
enough resolution to study submesoscale (1-20 km) salinity-dominated surface density
fronts. Dynamical instability of submesoscale fronts can lead to slumping of heavier water
under lighter water (Pollard and Regier 1992), i.e., fronts can enhance vertical stratification
of the near-surface ocean, a process known as restratification. We identified 17 distinct
submesoscale fronts along the ship track, out of which 14 fronts show a shallow mixed layer
under the front (Figure 2), suggesting active restratification (Timmermans 2012). We
propose that submesoscale fronts associated with pools/filaments of river and rain water
maintain shallow stratification in the north Bay of Bengal. Under the Ocean Mixing and
Monsoon (OMM) programme funded by MoES, we shall continue fine-scale observations to
study the physics of the near-surface ocean in different seasons.
Figure 1: Ship track of cruise ORV Sagar Nidhi during 26 Aug-4 Sep 2014. Total length of
track is 1800 km. Five density fronts analyzed are marked (red) with scales in kilometers.
55
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Figure 2: (a) Potential density (kg/m3) at 3 m depth as a funtion of distance. Front is marked
(cyan) and scales are mentioned in kilometers. (b) Depth profiles of potential density to the
left (black), right of the front (blue) and under the front (red). Mixed layer depth (MLD) is
marked in green dots. (c) Depth-sections of potential density as a function of along track
distance with density contours and MLD (white line). Contour interval is 0.1 kg/m3. Location
of profiles marked in thick black, red and blue lines on the top. (d) Depth-sections of Brunt
Vaisala frequency (N2; rad/s2) as a function of along track distance with density contours
and MLD (white line). Contour interval is 0.1 kg/m3.
References:
Gopalakrishna, V. V., et al. "Upper ocean stratification and circulation in the northern Bay of
Bengal during southwest monsoon of 1991." Continental shelf research 22.5 (2002): 791802.
Pollard, R. T., and L. A. Regier. "Vorticity and vertical circulation at an ocean front." Journal
of Physical Oceanography 22.6 (1992): 609-625.
Sengupta, Debasis, Bharath Raj Goddalehundi, and D. S. Anitha. "Cyclone‐induced mixing
does not cool SST in the post‐monsoon North Bay of Bengal." Atmospheric Science Letters
9.1 (2008): 1-6.
Sengupta, Debasis, G. N. Bharath Raj, and S. S. C. Shenoi. "Surface freshwater from Bay of
Bengal runoff and Indonesian throughflow in the tropical Indian Ocean." Geophysical
research letters 33.22 (2006).
Timmermans, Mary-Louise, and Peter Winsor. "Scales of horizontal density structure in the
Chukchi Sea surface layer." Continental Shelf Research 52 (2013): 39-45.
56
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22-24 March 2015
INFLUENCE OF INDO-PACIFIC SEA SURFACE TEMPERATURE ON THE
PRECIPITATION OVER NORTHWEST HIMALAYAS
V. M. Shakuntala1, J. V. Revadekar1, S. A. Ahmed2 and H. Varikoden1*
1
Indian Institute of Tropical Meteorology, Pashan, Pune-08; *[email protected]
Department of Geology, Central University of Karnataka, Gulbarga, Karnataka 585 311, India
2
Rainfall over the north-western Himalayas is vitally important due to recent
unpredictable flash floods and other kind of extreme events. Climate change, its vagaries
and short-lived extreme events are mainly controlled by regional topography and other
mode of large scale circulation patterns. Using the rainfall and Sea Surface Temperature
(SST) data, we tried to explore the influence of Indo-Pacific SSTs on rainfall over northwest
Himalayas. The rainfall over the northwest Himalaya is not coherent spatially with other
parts of Indian region. Therefore, the rainfall itself is unique in nature with extreme rainfall
events. In recent decades the region experienced frequent floods during southwest
monsoon period. From the correlation analysis, it is found that the rainfall is positively
correlated with Indo-Pacific SST. The correlation coefficients are significant at 0.01% level
over the northwest Pacific region; however, it is significant at 10% level over east equatorial
Indian Ocean. It is also imperative to understand the mechanism of floods over the region
and its relevance with the Indo-Pacific SSTs.
57
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22-24 March 2015
CLIMATOLOGICAL VARIATION OF CIRCULATION FEATURES OF THE NORTH
INDIAN OCEAN AND ITS INTERANNUAL VARIABILITY FROM TOPEX/POSIDEN
ALTIMETRY
R. Sen1*, A. Chakraborty2
1
Centre for Oceans, Rivers, Atmosphere and Land Sciences, Indian Institute of Technology Kharagpur, West
Bengal; [email protected]
2
Centre for Oceans, Rivers, Atmosphere and Land Sciences, Indian Institute of Technology Kharagpur,
West Bengal
The north Indian Ocean (NIO) can be divided roughly into three major areas based on
the circulation features and other meteorological characteristics: the equatorial belt
stretching between 10 N and 10 S, with the Somalia basin on its western end; the Bay of
Bengal (BOB); and, the Arabian Sea (AS). It is unique for the semiannual reversal of the
monsoon winds and due to twice changes of the monsoon winds, there are semiannual
reversal of upper ocean circulation of the NIO. The occurrence of the South-West Monsoon
(SWM) and the North-East Monsoon (NEM) over the ocean implies that the winds are
strongly seasonal and these variations are of large amplitude. Due to this variation of winds
different surface circulations are observed over NIO. Many works have been done
individually on the AS and on the BOB. Decade back a review work on the NIO currents was
reported but that is limited to large scale structure. Main aim of this paper work is to
provide a comprehensive review work on the NIO currents along with mesoscale eddies and
gyres for different months of the year. The seasonal geostrophic circulation patterns are
shown using Sea Surface Height Anomaly (SSHA) (January 1995 to December 2005)
climatology and Ocean Surface Current Analysis-Real time (OSCAR) climatology data
(January 1993 to December 2013) to reveal the monthly surface circulation pattern in the
ocean. These two climatological datasets are combined product of 11 and 21 years mean
respectively. Finally, the pictorial representations based on literature review and OSCAR
currents of NIO surface circulation associated with eddies and gyres are also shown. These
will help the new generation NIO modellers to validate their results and will be a
comprehensive base for feature modelling of this region. Interannual variation of eddy
activities indicates that El Niño may have an important impact on eddy genesis and these
have been shown using SSHA datasets (October 1992- December 2010). Seasonal and
monthly surface circulations of NIO using SSHA (maps of sea level anomalies /MSLA) and
OSCAR climatology datasets capture the surface currents of NIO such as East India Coastal
Current (EICC), Western Boundary Current (WBC), Summer Monsoon Current (SMC), Winter
Monsoon Current (WMC), West India Coastal Current (WICC), Somali Current (SC) and
Wyrtki Jet (WJ) although the duration of existence of such currents slightly differ from the
previous literature. The interannual variability of NIO surface circulation by Empirical
Orthogonal Function (EOF) analysis shows many oceanic events and its link with El-Nino
Southern Oscillation (ENSO).
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Figure 1: Monthly means of ocean surface
current (ms-1) from OSCAR for June. Colour
shading shows the magnitudes while the arrows
show the directions.
Figure 2: First interannual EOF of the NIO
surface circulation variability. (a) Spatial
structure of the first interannual EOF and (b)
Amplitude time series of the first interannual
EOF.
References
Shankar, D., P.N. Vinayachandran, A.S. Unnikrishnan. 2002. The monsoon currents in the
north Indian Ocean. Progress in Oceanography, 52, 63–120.
Shetye, S. R., I. Suresh, D. Shankar, D. Sundar, S. Jayakumar, P. Mehra, R. G. Prabhudesai,
and P. S. Pednekar, 2008. Observational evidence for remote forcing of the West India
coastal current. Journal of Geophysical Research 113, C1100, doi:10.1029/2008JC004874.
Sil. S., and Arun Chakraborty, M. Ravichandran. 2010. Numerical Simulation of Surface
Circulation Features over the Bay of Bengal using Regional Ocean Modeling System.
Advances in Geosciences, Vol. 24, 117-128.
Sil, S., and Arun Chakraborty. 2011. Simulation of East India Coastal Features and Validation
with Satellite Altimetry and Drifter Climatology. Ocean and Climate Systems, Vol. 2, No. 4,
279-289.
59
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22-24 March 2015
RETRIEVING OF TEMPERATURE AND SALINITY OF THE INTERIOR OCEAN
FROM HIGH RESOLUTION SATELLITE SEA SURFACE TEMPERATURE
D. Sarkar1*, A. Chakraborty2, Raj Kumar3, Rashmi Sharma3
1
[email protected]
2
[email protected]
3
Atmosphere and ocean sciences group, EPSA, Space Application Centre, Ahmedabad
Temperature and Salinity are key parameters for the forecast of ocean states.
Accurate forecast of ocean state using numerical model requires accurate initial T-S profiles
of the ocean. Model generally uses climatic T-S profiles as back ground. Model is integrated
for certain time to attain quasi-equilibrium state from which initial condition is used for
forecast simulation. The model internal variability moves the forecast initial condition from
accuracy. In this study an algorithm is being developed to fill up the above gap. A
methodology is being presented to generate the 3-D structure of temperature and salinity
fields using high resolution satellite derived sea surface temperature. In the steady state
case, the heat equation in the thermocline and deep zones is the balanced of vertical
advection with vertical diffusion as the other terms are being small with comparison. The
convergence and divergence in the mixed layer lead to circulations in the deeper water. For
a short time scales, the vertical transfer dominate and horizontal advection and diffusion
may be neglected (Pond and Pickard, 1983). Combining steady state heat equation (Pond
and Pickard, 1983) for thermocline and deep zones and steady state temperature equation
(Pond and Pickard, 1983) for mixed layer, a structure function (  ) can be defined as,
T ( x, y, z )  Tb ( x, y ) for 0  z  H
 ( x, y , z ) 
.Using structure function we reconstructed
Ts ( x, y )  Tb ( x, y )
the three dimensional temperature (T) structure in the reverse process with Sea Surface
Temperature input as, T ( x, y, z )  Ts ( x, y)  Tb ( x, y)  ( x, y, z )  Tb ( x, y) for0  z  H . The
salinity structure is determined by using the structure of conductivity ratio ( R CNDR ) following
Fofonov and Millard (1983) as, RCNDR  R p  RT  rT  C (S , T , p)
. This can be
C (35,15,0)
useful to generate synoptic initial condition which is required for short term Regional Ocean
model forecasting. It has been validated using October 2008 TMI Satellite pass as well as
ARGO floats over Bay of Bengal. The root mean square error is very less in both at the
surface and greater depth. The salinity profiles are in good agreement with ARGO profiles in
conductivity approach calculation compared to TS-diagram approach.
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Fig.1. Vertical profile of Structure function
(φ) over Bay of Bengal (75°E to 100°E, 0°N to
20°N) for January.
Fig.2. Vertical profile of Root Mean Square
Error of temperature over Bay of Bengal
(75°E to 100°E, 0°N to 20°N) for January,
2008.
Fig. 3. vertical structure of temperature using structure function over Bay of Bengal for the
month of January to June, 2008 at 88°E and 0°N to 20°N.
References:
Boyer, T. P., S. Levitus, H. E. Garcia, R. A. Locarnini, C. Stephens, and J. I. Antonov, 2005:
Objective analyses of annual, seasonal and monthly temperature and salinity for the World
Ocean on a 0.25°grid. Int.J. Climatol., 25, 931-945.
Carolina, N., 2009: NAO impact on Gulf of Maine Circulations during 1995. M.Tech thesis,
School of Marine Science and Technology, University of Massachusetts, Dartmouth, USA.
C. Maes and D. Behringer, 2000: Using satellite-derived sea level and temperature profiles
for determining the salinity variability: A new approach. J. Geophys, Res., vol. 105, no. C4,
pp 8537-8547.
C. Maes, 1999: A note on the vertical scales of temperature and salinity and their signature
in dynamic height in the western Pacific Ocean: Implications for data assimilation. J.
Geophys. Res., vol. 104, no. C5, pp. 11037-11048.
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SUBSURFACE TEMPERATURE BIAS IN THE EQUATORIAL INDIAN OCEAN IN
NCEP CLIMATE FORECASTING SYSTEM
G. Srinivas*, J. S. Chowdary, Rashmi Kakatkar, Anant Parekh and C. Gnanaseelan
Indian Institute of Tropical Meteorology, Pune-411008; [email protected]
Abstract
This study examine the factors responsible for equatorial Indian Ocean subsurface
temperature biases in National Centers for Environmental Prediction Climate Forecasting
System version 2 (CFSv2). CFSv2 is a fully coupled ocean-atmosphere-land model with
advanced physics and increased resolution. The model is integrated over a period of 100
years, and used the climatology of last 60 years for the present study. It is noted that the
model displays strongest Sea Surface Temperature bias (SST) cold bias (~2°C) in the Tropical
Indian Ocean (TIO) during boreal spring and fall seasons. Whereas subsurface temperature
near Thermocline depth is warmer throughout the year with maximum bias during summer
and fall seasons. In particular, subsurface bias around 100m depth is stronger in the western
equatorial Indian Ocean, which is mainly due to misrepresentation of equatorial currents in
the model. Equatorial surface and subsurface current bias in CFSv2 is mainly due to the
unrealistic representation of winds over the TIO. Therefore in order to improve the vertical
thermal structure of TIO in CFSv2, it is essential to reduce the biases in surface wind forcing
and improve the vertical mixing processes.
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A REVIEW OF LATE HOLOCENE CLIMATE CHANGE FROM WESTERN INDIA:
HUNTING ARCHIVES FOR RECONSTRUCTING HIGH RESOLUTION CLIMATE
DYNAMICS
Nisarg Makwana1*, S.P. Prizomwala1, N.P. Bhatt2, B.K. Rastogi1
1
Institute of Seismological Research, Raisan, Gandhinagar 382009; [email protected]
2
Department of Geology, The M. S. University of Baroda, Vadodara 390002
Indian Summer Monsoon (ISM) is considered as chief governing factor for climate
variability in the Indian subcontinent. The ISM variability during the Holocene period has
been topic of research since long and hence now there exist a fairly good understanding at
millennial to centennial scale variations. However there is a vital need to reconstruct the
climatic variability at multi-decadal scale. The climatic variability during the Late Holocene
period (i.e. Last 4ka) has been reported by few suggesting a dry climate during 3.5 to 4 ka,
followed by fluctuating strength of ISM during 3.5 to 2 ka. The strength of ISM increased
during 2ka to 1.5 ka followed by a short dry spell and again increase in strength from 1ka to
0.6ka. Few studies have even documented the dry spell at 0.2 ka correlating with the Little
Ice Age. However there is a need to explore more archives which would help in
reconstructing high resolution multidecadal climatic variability of ISM. This is of vital
importance as this period coincides with the collapse of the neighbouring Indus Valley
civilization.
Gujarat region in western India, experiences semi-arid to arid climatic regime with
90% precipitation derived from the ISM. The mighty Great and Little Rann of Kachchh has
not been studied for palaeoclimatic reconstruction but is considered to be a depocenter
since Holocene period. Similarly mudflats of Gulf of Kachchh and Gulf of Khambhat show a
monotonous geomorphology and dominant depositional processes compared to erosional
pattern. The sediments to these archives are derived from hinterland rivers, where semiarid climate prevails with characteristic episodic discharge. This makes them sensitive to
abrupt climatic fluctuations. The processes acting in these environments hint them to be
robust archives for reconstructing palaeoclimatic fluctuations. Preliminary chronological
constraints suggest the mudflats of Gulf of Kachchh and Great Rann of Kachchh have a high
sedimentation rate (> 2mm/a) and hence may serve as robust archives to reconstruct high
resolution climatic fluctuations during the Late Holocene period.
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NUDGING OF THERMODYNAMIC PROFILES: IMPACT ON REPRESENTATION OF
INDIAN SUMMER MONSOON
Raju Attada, Anant Parekh*, C. Gnanaseelan and J. S. Chowdary
Indian Institute of Tropical Meteorology, Pune 411 008; [email protected]
The study examines the impact of assimilation of thermodynamic soundings from AIRS
satellite on simulation of Indian summer monsoon (ISM). Two experiments are carried out
for the period of 2003 to 2011, the first one (CTRL) is forced with the NCEP FNL while the
second one is same as first one but AIRS retrieved temperature profiles (TQEXP) are
assimilated throughout the model integration using nudging technique. Assimilation of
these profiles shows significant improvement in the simulation of ISM as follows. (1) The
strength and location of circulation elements are improved. (2) Unrealistic double ITCZ like
rainfall pattern disappeared. (3) The meridional distribution of pressure, temperature,
moisture field, MSE and wind shear have improved. (4) Vertical structure of moisture,
vorticity, divergence and vertical velocities also improved.
Assimilation of satellite retrieved temperature and water vapour profiles could
significantly improve the moist physical process over MT region associates with ISM. TQEXP
showed improved spatial distribution of precipitation and improved statistical skills scores
over the land regions compared to CTRL. The assimilation of temperature and moisture
profiles data improves the thermodynamic structure and it influences the moisture
convergence and the associated spatial distribution of precipitation patterns through
dynamic interaction of deep convection with the boundary layer. It indicates that
assimilation of temperature and water vapour complements each other in a consistent way.
Finally, the assimilation is performed throughout the entire simulation, showing how the
proposed approach can be used to improve meteorological analyses in terms of moist
convection and rainfall associated to ISM. On the other hand, there are few some zones
where the assimilation performs poorly with respect to the precipitation simulation. This
strongly advocates the need of improvements in the parameterized physics and the
dynamical core of the model.
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INTERCOMPARISON OF NIOT WAVE BUOY DATA WITH DATAWELL
WAVERIDER BUOY
J. Vimala1*, K. Ramesh2, G. Latha2 and R. Venkatesan2
1
Research Scholar, Sathyabama University, Chennai; [email protected]
2
National Institute of Ocean Technology, Chennai
Under the moored buoy programs of National Institute of Ocean Technology (NIOT),
ocean wave measurements are made. In order to compare the wave parameters derived
from these measurements using Motion Reference Unit (MRU) sensor, another datawell
waverider (DW) buoy has been acquired and both the buoys were deployed off Agatti within
a spacing of 1.4 nm. The work carried out on inter comparison of wave parameters such as
significant wave height, zero crossing wave period, peak period and wave spectrum for the
period from April 2011 to November 2011. The comparison of the time series wave
parameter obtained from both buoys shows good agreement. The correlation coefficient of
the significant wave height, peak period and zero crossing wave periods are 0.87, 0.69 and
0.65 respectively. The trend in the variation of wave spectrum matches well for both buoys
with datawell waverider buoy measure higher wave energy. The major reason could be the
different locations of observation and the measurement interval.
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SOIL MOISTURE DURING SOUTHWEST MONSOON PERIOD AND ITS RELATION
WITH INDIAN OCEAN SEA SURFACE TEMPERATURE
H. Varikoden1*and J. V. Revadekar1,
1
Indian Institute of Tropical Meteorology, Pashan, Pune-08; [email protected]
Soil moisture plays an important role in global and regional scale climate systems by
modulating the surface albedo and on the partitioning between sensible and latent heat
fluxes. Many global and regional climate modeling studies have stated the importance of
the initialisation of the soil moisture in their simulations of regional hydrological
distribution. Soil moisture is considered as one of the important parameter in the prediction
of hydrological parameters during the southwest monsoon season. However, it is not in
common use due to its inconvenience in measurement. Very recently satellite soil moisture
data is made available from 1979 onwards with high spatial resolution. Using these satellite
based measurement, we have tried to understand the role of soil moisture and sea surface
temperature on rainfall. On seasonal scale, the spatial pattern of soil moisture and rainfall
are not similar, however, the annual cycle follows the unimodal variation. Sea surface
temperature over the Bay of Bengal show negative correlation with the central Indian soil
moisture even though the rainfall over this region is higher. This may be due to the
topographic influence and presence of large river basins. This needs to be studied in detail.
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RESPONSE OF BAY OF BENGAL TO CYCLONE PHAILIN FROM MOORED AND
SATELLITE DATA
Chaudhuri. D1*, Vekatesan. R2, Ravichandran. M3, Sengupta. D4
1
CAOS, Indian Institute of Science, Bangalore; [email protected]
National Institute of Ocean Technology (NIOT), Velachery–Tambaram Main Road, Pallikaranai, Chennai
3
Indian National Center for Ocean Information Services (INCOIS), Hyderabad
4
CAOS, Indian Institute of Science, Bangalore
2
Cyclone Phailin is the second-strongest tropical cyclone ever to make landfall in India
(IMD 2013, Venkatesan 2013). Phailin matured over the Bay of Bengal (BoB) during 9-14
October 2013. The response of the upper-ocean to Phailin is analyzed with the help of in
situ observations from an NIOT mooring BD10 and Argo float 2901335 directly under the
storm; and NIOT moorings BD08, BD09 and an INCOIS mooring near 18°N, about 200 km to
the right of the storm track. We also use satellite observations: Aquarius Sea Surface Salinity
(SSS) and TMI/AMSRE Sea Surface Temperature (SST). Our main findings are that (i) As
expected for post monsoon cyclones in the north Bay of Bengal (Sengupta 2008), SST
cooling is small (≈ 0.2ºC). (ii) Post-storm SSS increases by 1.6 psu at the three moorings near
18°N (Figure 1); the change in Aquarius SSS agrees with the moored observations. SSS
increases by 2-4 psu close to the storm track, due to storm induced vertical mixing to at
least 50m depth. (iii) SSS increases throughout the western Bay (Figure 2) after the passage
of the storm. (iv) The largest-amplitude inertial currents (0.5 m/s) are observed directly
under the cyclone. (v) Velocity observations from an Acoustic Doppler Current Profiler
(ADCP) on mooring BD09 suggest that shear-induced mixing (D'Asaro 2014) deepens the
mixed layer from pre-storm values of less than 10m to about 50 m after the storm. (vi)
Estimates of energy input from wind stress indicate that about 60 percent of the energy
goes into increased potential energy of the water column due to vertical mixing.
Figure 1: Hourly a) Wind stress b) c) d) time series of salinity from three moorings at
different depths.
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Figure 2: Post (16-21 October 2013) minus Pre- (3-8 October2013), a) TMI/AMSRE Sea
Surface Temperature (0.25º daily), b) Aquarius Sea Surface Salinity (1º daily).
References:
D'Asaro, E. A., Black P. G., Centurioni, L. R., Chang, Y. T., Chen, S. S., Foster, R. C., Graber, H.
C., Harr, P., Hormann, V., Lien, R. C., Lin, I. I., Sanford, T. B., Tang, T. Y., and Wu, C. C., Impact
of typhoons on the ocean in the pacific. Bull. Amer. Meteor. Soc.,2014, 95, 1405–1418.
IMD, 2013. Very severe cyclonic storm. Phailin over the Bay of Bengal (8–14 October 2013):
a report India Meteorological Department, New Delhi, p. 43, (2013).
Sengupta, D., Bharath Raj, G. and Anitha, D. S., Cyclone-induced mixing does not cool SST in
the post-monsoon north Bay of Bengal. Atmos. Sci. Lett., 2008, 9, 1–6.
Venkatesan, R., Simi Mathew, J. Vimala, G. Latha, M. Arul Muthiah, S. Ramasundaram, R.
Sundar, R. Lavanya, and M. A. Atmanand. "Signatures of very severe cyclonic storm Phailin
in met–ocean parameters observed by moored buoy network in the Bay of Bengal", Current
Science, 2014, 107(4), 589.
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INDIAN SUMMER MONSOON AND THE OCEAN HEAT BUDGET SIMULATED IN
CFSV2 MODEL
Gibies George1*, D. Nagarjuna Rao1, C.T. Sabeerali1, A. Suryachandra Rao1
1
Indian Institute of Tropical Meteorology, Pune; [email protected]
As a result of cold SST bias in the tropical Indian Ocean, the seasonal mean rainfall
over the Indian landmass is underestimated in the CFSv2 hindcast run. Simulated weak
monsoon results in simulating westerly wind core associated with AISMR located along the
equator while in observation there is clear cross equatorial flow. This is because the
tropospheric temperature gradient in CFSv2 hindcast run is not strong enough to drive the
cross equatorial flow. Analysis have clearly highlighted that the prediction skill of All India
Summer Monsoon Rainfall (AISMR) in CFSv2 is basically coming from the ENSO-monsoon
relationship in the model and it is reasonably captured. Further, it is noticed that the cold
SST bias in the tropical Indian Ocean is to be minimized to improve the magnitude of the
AISMR simulation whereas the correct representation of Indian Ocean coupled dynamics is
essential to improve the AISMR prediction skill. Therefore, this study highlights the need to
improve the Indian Ocean coupled dynamics in CFSv2 for the further improvement of
simulation and prediction skill of AISMR.
The model simulate major precipitation zones reasonably well except that there is
underestimation of land rainfall and overestimation of ocean rainfall. The model simulate
enhanced precipitation over Konkan coast of Arabian Sea, Myanmar coast of Bay of Bengal,
Foot hills of Himalaya, Indonesian coast in the eastern equatorial Indian Ocean, Philippine
coast and the western Pacific. The model underestimate the precipitation over land region
especially northwest India, Pakistan, Srilanka and South America. Strong dry bias is observed
in Indian land region and South America, while there is strong wet bias over tropical Indian
Ocean and western Pacific. These biases are also noticed in many of the CMIP models
(Sabeerali et al., 2013). Saha et al. (2012a) have studied the relation between Indian Land
Dry Bias and Eurasian Snow Cover. The surface fluxes during JJAS try to warm northern
Indian Ocean and cool southern Tropical Indian Ocean. But this is balanced by the horizontal
transport of warm water. In CFSv2 overestimation of the southward heat transport from
Arabian Sea, and underestimated surface fluxes results cold bias over Arabian Sea. On the
other hand underestimated westward heat transport from Indonasian region and
overestimated surface fluxes results in cold bias over southern tropical Indian Ocean.
References:
C. T. Sabeerali, A. Ramu Dandi, Ashish Dhakate, Kiran Salunke, S. Mahapatra, and A.
Suryachandra Rao. Simulation of boreal summer intraseasonal oscillations in the latest
CMIP5 coupled GCMs. J. Geophys. Res. Atmos., 118(10):4401–4420, May 2013. ISSN
2169897X. doi: 10.1002/jgrd.50403.
Subodh K. Saha, Samir Pokhrel, and Hemantkumar S. Chaudhari. Influence of Eurasian snow
on Indian summer monsoon in NCEP CFSv2 freerun. Clim. Dyn., 41(7-8):1801–1815,
December 2012a. ISSN 0930-7575. doi: 10.1007/s00382-012-1617-4.
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Suranjana Saha, Shrinivas Moorthi, Xingren Wu, and Jiande Jun Wang. The NCEP climate
forecast system version 2. J. Clim., 2:1–61, 2012b.
Zuojun Yu, Julian P. McCreary, Max Yaremchuk, and Ryo Furue. Subsurface Salinity Balance
in the South China Sea. J. Phys. Oceanogr., 38(2):527–539, February 2008. ISSN 0022-3670.
doi: 10.1175/2007JPO3661.1.
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PREDICTION AND ERROR GROWTH IN THE DAILY FORECAST OF
PRECIPITATION FROM THE NCEP CFSV2 OVER THE SUBDIVISIONS OF INDIAN
CONTINENT
Shailendra Rai1, *, Dhruva Kumar Pandey1, A. K. Sahai2 and S. Abhilash2
1
K. Banerjee Centre of Atmospheric and Ocean Studies, University of Allahabad; [email protected]
2
Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, Pashan, Pune.
The understanding in the peculiarity of the Indian summer monsoon and its accurate
prediction is still a challenge for the scientific community involved in the process. In the
present study we have used Climate Forecast System version 2 (CFSv2) of National Centre of
Environmental Prediction (NCEP). The CFSv2 is a fully coupled general circulation model
used in seasonal forecasting (Saha et al. 2010). Recently, CFSv2 has been extensively used by
India for operational long range prediction under ‘National Monsoon Mission’ (NMM)
(Abhilash et al. 2013) and reliable prediction was obtained (Sharmila et al. 2013).
The main focus of the previous studies are related to summer monsoon rainfall over
the entire India as a whole and very few studies are related with the predictability studies
over sub-divisional level. However, the accurate and timely prediction at sub-divisional level
is also important keeping in mind the needs in terms of agriculture, power etc. of the
population living in these regions. The main goal of the present study is to investigate the
forecast skill and predictability of the south Asian monsoon in CFSv2 on daily time scale for
the whole Indian region and the different regions of the Indian subcontinent.
In the present work, we have used the CFSv2 model runs with the initial conditions on
31 May, 30th June, 30th July, 29th August and 28th September during 2001-2013 having 11
ensemble members and each run gives forecast for 45 days (Abhilash et al. 2013). We will
denote the forecast initialized on 31st May, 30th June, 30th July, 29th August and 28th
September as June, July, August, September and October forecast respectively.
st
It has been observed that the daily mean climatology of precipitation over the land
points of India is underestimated in model forecast as compared to observation. The
monthly model bias of precipitation shows the dry bias over the land points of India and also
over the Bay of Bengal, whereas the Himalayan and Arabian Sea regions show the wet bias.
We have divided the Indian landmass in five subdivisions namely Central India, Southern
India, Western Ghat, North East and Indonesian region based on the spatial variation of
mean observed precipitation in JJAS season. The underestimation over the land points of
India during mature phase was originated from the Central India, Southern India and
Western Ghat regions.
We have computed forecast error by taking the difference between the predicted
value and the observed value on each calendar day of each year. Further, we calculated root
mean square error (RMSE) during 2001-2013 for each ensemble member and the ensemble
mean is taken. It was observed that the error growth in June forecast is slower as compared
to July forecast in all the regions. We have computed predictability error of a model by
taking one ensemble member as truth and taken difference of precipitation from rest of the
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ensemble members with this member. The error in the forecast is due to the uncertainty in
the initial conditions and predictability error gives the upper bound of predictability of the
model (Lorenz 1982). The predictability error also grows slowly in June forecast as
compared to July forecast in most of the regions.
Table 1: The doubling time of errors of the NCEP CFSv2 forecast for different indices
initialized on 31st May (June forecast) and 30th June (July forecast).
Regions
June Forecast
July Forecast
IMR (Indian Monsoon Region)
4.4
3.5
Central India
4.4
3.6
Indonesia Region
3.9
3.4
North East
3.7
3.4
Southern India
3.3
3.6
Western Ghats
3.2
3.4
We have estimated the predictability error quantitatively using the empirical formula
by Lorenz (1982). The doubling time of predictability error was estimated to be in the range
of 3-5 days for all the regions and is shown in table 1. It is clear from the table that the
Southern India and Western Ghat are more predictable in the July forecast as compared to
June forecast, whereas IMR, North East, Central India and Indonesian regions are having the
opposite nature.
References:
Abhilash S., Sahai A. K., Pattnaik S., Goswami B. N., Kumar A. (2013), Extended range
prediction of active-break spells of Indian summer monsoon rainfall using an ensemble
prediction system in NCEP climate forecast system, Int J Climatol, 34, 98-113. doi:
10.1002/joc.3668.
Saha S. K., Pokhrel S., Chaudhri H. S., Dhakate A., Shewale S., Sabeerali C. T., Salunke K.,
Hazra A., Mahapatra S., Rao A. S. (2014), Improved simulation of Indian summer monsoon in
latest NCEP climate forecast system free run. Int J Climatol 34:1628–1641. doi:
10.1002/joc.3791.
Sharmila S., Pillai P. A., Joseph S., Roxy M., Krishna R. P. M., Chattopadhyay R., Abhilash S.,
Sahai A. K., Goswami B. N. (2013), Role of ocean– atmosphere interaction on northward
propagation of Indian summer monsoon intra-seasonal oscillations (MISO), Clim. Dyn., 41,
1651–1669. doi: 10.1007/s00382-013-1854-1.
Lorenz E. N. (1982) Atmospheric predictability experiments with a large numerical model.
Tellus, 34, 505–513, doi: 10.1111/j.2153-3490.1982.tb01839.x.
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MODELING THE HYDROGRAPHY AND CIRCULATION OF THE BAY OF BENGAL
USING A HIGH-RESOLUTION OCEAN CIRCULATION MODEL
Atul Srivastava1,2*, Suneet Dwivedi1,2 and Alok Kumar Mishra1,2
1
M N Saha Centre of Space Studies, University of Allahabad, Allahabad, UP 211002; [email protected]
2
K Banerjee Centre of Atmospheric and Ocean Studies, University of Allahabad, Allahabad, UP 211002
A limited-area high-resolution Bay of Bengal Circulation Modeling has been performed
using the MITgcm in the region [80E-95E; 5N-20N] for a period of 15 years from 1998-2012
followed by a spin-up run during the years 1993-1997. The model uses the horizontal
resolution of 10 km and the highest vertical resolution of 5 m. The model uses the open
boundary condition on all sides and is forced with the 6-hourly NCEP reanalysis air-sea
forcings, namely air temperature, relative humidity, zonal and meridional winds,
downwelling shortwave and longwave radiations, precipitation and evaporation. The eddyresolving mesoscale model results of hydrography (temperature and salinity) are compared
and contrasted with ORAS4 and GODAS reanalysis data. The area averaged SST anomaly
over the domain [85E-90E; 8E-16E] depicts strong monthly variability. It decreases from
June to January and starts increasing from February to May. The months of January and May
show minimum and maximum SST anomaly over the domain, respectively. The subsurface
temperature and salinity values are also well matched with the observations. The variability
of the mixed layer depth is also examined. It is found that the MLD maximum is observed
during the winter season. The zonal and meridional currents are compared with the OSCAR
data. The heat-flux through the region is also computed.
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USING THE TELESCOPICALLY VARYING HORIZONTAL AND VERTICAL GRIDS
FOR MODELING THE INDIAN OCEAN VARIABILITY
Anupam Kumar Dixit1* and Suneet Dwivedi1,2
1
K Banerjee Centre of Atmospheric and Ocean Studies, University of Allahabad, Allahabad, UP 211002;
[email protected]
2
M N Saha Centre of Space Studies, University of Allahabad, Allahabad, UP 211002
Efforts are made to run an ocean circulation model, MITgcm over the Indian Ocean in
the domain [45°E-130°E; 25°S-25°N]. The model uses the open boundary conditions. The
bathymetry is derived from the Smith and Sandwell’s data. The air-sea forcings are
extracted from the Common Ocean-ice Reference Experiments version 2 (CORE II) data. The
model uses telescopic horizontal grid with maximum horizontal resolution of 10 km in the
domain [65°E-95°E; 5°N-25°N] and then telescopically increasing to 100 km. Similarly,
maximum horizontal resolution of 5m is taken near the surface and then gradually increased
to 500m near the ocean floor. The model is spun-up for years 1984-1988. The simulation run
is carried out for the years 1989-2007. The model output is compared to the GODAS data.
The results indicate that the hydrography and circulation properties are very well simulated
by the model over the region of study. The well known SST anomaly index, namely, the
Indian Ocean Dipole (IOD) is also compared with the observation. The Bay of Bengal and
Arabian Sea salinity variability is also examined on a seasonal and interannual basis. The
effect of monsoon rains and runoff from Ganga, Brahmaputra, Godavari, and other
neighbouring rivers is also examined in this context. The Indonesian throughflow is also
computed.
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POSSIBLE INTERACTIONS BETWEEN SUBSURFACE OCEAN BIASES AND THE
SURFACE INTERANNUAL VARIABILITY IN COUPLED MODELS.
Shikha Singh1*, Vinu Valsala1
1
Indian Institute of Tropical Meteorology, Pune; *[email protected]
Analysis for the possible impacts of deep ocean biases on the surface variability of
interannual signatures in the model is carried out. Few candidate models (CFSv2 and IITMEarth System Model) and outputs from selected CMIP-5 models are analyzed. CFSv2 is a
coupled ocean atmosphere model by NCEP and it is the core-part of the IITM-ESM. Both in
CFSv2 and in IITM-ESM, when used for climate simulations of hundred-years, the models
develop internal warm bias in the Indian Ocean, which is a property commonly observed in
other CMIP-5 candidate models considered here as well. In CFSv2 and IITM-ESM, it is also
seen that there are occurrences of Indian Ocean Dipole in the early part of the year within
Jan-April, whereas in reality, IOD starts in May-June, peaks in September and decays by
November-December of the year. The possible role of internal biases in the IOD is
hypothesized using the relation between the Brunt-Vaisala frequency and baroclinic wave
speeds (i.e. WKJB approximation). Using both WKJB approximation and the normal mode
decomposition (Chelton et al., 1998), it is seen that most of the models analyzed here have
a higher baroclinic speed compared to the observations. Since the wave dispersion is faster,
it has a possibility to affect the planetary scale events such as IOD in terms of their life cycle,
periodicity, seasonality and the duration.Further analysis based on simple oceanatmospheric coupled models is utilized to examine the role of ocean biases in the
interannual variability of the tropical oceans.
References:
Chelton, D.B., de Szoeke, R.A., Schlax, M.G., El Naggar, K., Siwertz, N., 1998. Geographic
variability of the first baroclinic Rossby radius of deformation. Journal of Physical
Oceanography 28, 433–460.
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NORTH-SOUTH HEMISPHERIC THERMAL CONTRAST AND INDIAN SUMMER
MONSOON RAINFALL VARIABILITY
Lekshmi Mudra. B1* and H. N. Singh2
1
Academy of Climate Change Education & Research, Thrissur, Kerala; [email protected]
2
Indian Institute of Tropical Meteorology, Pune
Rainfall variability across the country and its possible causes in the wake of changing
global climatic scenario is multifold. Some extreme weather and climate events have
increased in recent decades. The understanding of the science of climate changes and its
impact has been an important thrust area amongst the atmospheric researchers due to its
strong influence on the socio-economy. The 2.5 DSG isobaric level meteorological
parameters (years 1949-2014) viz. MSLP, Surface Temperature, Sea Surface Temperature,
Precipitable water, cloud cover, geopotential height at different isobaric levels, temperature
a different isobaric levels, etc) downloadable from the NCEP/NCAR reanalysis have been
analyzed for better understanding of the monsoon system as well as the possible causes of
decreased monsoon rainfall in the wake of global warming. The characteristics of various
meteorological parameters for five good monsoon years and five weak monsoon years have
been analysed to understand their distinct features. The spatio-temporal variability of the
composite as well as anomaly of the good and weak monsoon years for various parameters
has also been analysed. Similar analysis was repeated for the five strong El-Nino and five LaNina years. Global pattern of change in tropospheric parameters from 1949‒1978 to
1979‒2014 have been examined. The tropospheric temperature (TT: 1000-200-hPa) across
the globe has been experiencing a heterogeneous increase since 1979. Compared to the
period 1949–1978, the rise in the TT over different climatic zones is different. During
monsoon season (JJAS: June through September), the rise in the TT over equatorial belt is
0.45°C, the north polar 0.60°C, the north subtropic +0.32°C, the south subtropic +0.77°C and
the south polar region +0.66°C, higher increase in polar regions than equator. Though rising
over different climatic zones, the temperature over the Southern Hemisphere is rising at a
faster rate than that of the Northern Hemisphere resulting into reduction of the
tropospheric temperature gradient (TTG) from Northern Hemisphere to Southern
Hemisphere. The reduction in the TTG from north extratropic to south extratropic is by
0.95°C, from north temperate to south temperate 1.01°C and from Arctic to Antarctic
1.11°C. Similar pattern have also been observed for the tropospheric (1000-200-hPa)
geopotential thickness. The main effects of this reduction in the north-south thermal
contrast are the weakening of the general atmospheric circulation and the Asia-Pacific
monsoon circulation. Consequently, the easterlies were weakened but raised the SSTs over
the Niño region.
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STUDY OF INDONESIAN THROUGHFLOW USING HYBRID COORDINATE OCEAN
MODEL
Vivek Kumar Pandey*, Sudhir Kumar Singh, Satyam Srivastava
K. Banerjee Centre of Atmospheric and Ocean Studies, Institute of Interdisciplinary Studies, University of
Allahabad, Allahabad, UP 211002, INDIA; [email protected]
We are representing here the application of the “HYbrid Coordinate Ocean Model
(HYCOM)” for the world’s most complicated geometry Indonesian Throughflow, which is
isopycnal in the open, stratified ocean, but uses the layered continuity equation to make a
dynamically smooth transition to a terrain-following coordinate in shallow coastal regions,
and to z-level coordinates in the mixed layer and/or unstratified seas. The hybrid coordinate
extends the geographic range of applicability of traditional isopycnic coordinate circulation
models. HYCOM is designed to provide a major advance over the existing operational and
preoperational global ocean prediction systems, since it overcomes design limitations of the
present systems as well as limitations in vertical and horizontal resolution. It maintains the
significant advantages of an isopycnal model in stratified regions while allowing more
vertical resolution near the surface and in shallow coastal areas, hence providing a better
representation of the upper ocean physics and become more streamlined system with
improved performance for coastline, shallow and complicated ocean geometry of the IndoPacific region.
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ROLE OF UPPER OCEAN STRATIFICATION IN THE INTENSIFICATION OF THE
SEVERE CYCLONE “HUDHUD”
K.Maneesha*, Y.Sadhuram and V.S.N.Murty
CSIR- National Institute of Oceanography, Regional centre, Visakhapatnam- 530017 [email protected]
The recent cyclone “Hudhud” formed on 7th October 2014 as a depression over north
Andaman Sea and crossed Visakhapatnam on 12th October 2014 as a very severe cyclone.
This is the first cyclone to hit Visakhapatnam after 30 years .The central pressure was 950
Hpa (drop of 54 Hpa) and the maximum wind was more than 100 knots (www.imd.gov.in).
The importance of upper ocean heat content (UOHC) and eddies in the intensification
of cyclones over Bay of Bengal have been reported earlier1,2 . A threshold value of >60
kj/cm2 has been identified for the intensification of a cyclone during pre (March-May) and
post monsoon (October –December) seasons over Bay of Bengal. It is found that slow (fast)
moving cyclones require high (low) UOHC to intensify. In general, slow moving storm
induces surface cooling and results in negative feed back from the ocean which does not
favor intensification. In case of Hudhud, the UOHC along the track varied from 45-110 kj/cm
2
and the vertical wind shear is of the order of 10-20 knots (www.imd.gov.in) which is not
favourable for intensification. Surprisingly, the storm reached very high intensity ( T4.0 to
T5.0) from 11th to 12th October , before crossing the Visakhapatnam city. The possible
explanation for the intensification is examined in this preliminary study using the Argo , in
situ and model outputs prior and during the cyclone. Data on cyclone track and other details
are taken from IMD website (www.imd.gov.in). The following equations are used to
compute UOHC and UOHC with stratification (S) (UOHCs).
Stratification (S) is computed from the Brunt –Vaisala frequencies (Nmax & No)
(1)
√
∫ (
UOHCS =UOHC*S
)
(2)
(3)
Normally , in most of the earlier studies , UOHC is computed from eq.2 which does not
consider stratification while in eq.3 ., stratification (S) is considered to estimate UOHC .The
climatological value of S ranges from 2 to 4 in Bay of Bengal during post monsoon season 1.
Translation speeds (TS) are computed at 3 hourly interval from the track of the cyclone
(www.imd.gov.in) and found to be low ( 1-3 m/sec) . Just before the cyclone, high SST
(>29.5oC) and low salinities 29-31 PSU were observed in the western Bay of Bengal. This may
be due to the heavy rainfall occurred during September 2014 along east coast of India.
HYCOM +NCODA model out puts are also showing the high water influx along the east coast
of India. Hence high values of S ( >4 ,higher than the climatological value) were observed in
the western Bay of Bengal which caused a high value of UOHCs ( >300 KJ/cm2 ), double to
the climatological value (120 KJ/cm2 ) . This high UOHCs opposes the surface cooling
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induced by the storm and helps in the intensification by supplying the enthalpy flux which
was also found to be higher ( 180-280 w/m2 ), double the climatological values.
From this preliminary study, it is inferred that the upper ocean stratification off
Visakhapatnam might have helped in the intensification of the cyclone “ Hudhud”even
though the vertical wind shear (10-20 knots) is not favourable.
References:
Maneesha, K., 2012: Role of upper ocean in the intensification and movement of tropical
cyclones and their associated biogeochemical response in the Bay of Bengal., Ph.D., Thesis,
submitted to Andhra University, Visakhapatnam
Sadhuram, Y., Maneesha, K., and Ramana Murty, T.V., 2012: Intensification of Aila (2009)
due to a warm core eddy in the north Bay of Bengal, Nat. Hazards., 63, 1515-25
79
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SEASONAL CHANGE IN THE TROPICAL CYCLONE CHARACTERISTICS BETWEEN
PRE- AND POST-MONSOON SEASONS IN THE BAY OF BENGAL: RESPECTIVE
INFLUENCE OF THE OCEAN AND ATMOSPHERE
M. Teesha 1, S. Neetu 1, M. Lengaigne 1,2, J. Vialard 2, G. Samson 1
1
CSIR-National Institute of Oceanography, Goa, India, [email protected] ,[email protected]
Laboratoire d'Océanographie Expérimentation et Approches Numériques,IRD/ CNRS/ UPMC/ MNHN , Paris,
France
2
The North Indian Ocean accounts for 7 % of global tropical cyclones with larger
number of cyclones in Bay of Bengal (BoB) compared to Arabian Sea, which poses serious
threat to the vulnerable coastal countries .14 of the 20 deadliest tropical cyclones in history
formed over BoB. The two primary cyclone seasons in BoB are pre-monsoon and postmonsoon. It has been demonstrated that stronger upper ocean salinity stratification and
deeper thermal stratification reduce the surface cooling under the TCs during the postmonsoon, and this inhibited cooling may promote the surface evaporation and releases
large amount of latent heat, which is the fuel for intensification of cyclones. This leads to
suspect more stronger cyclones in the post-monsoon as compared to the pre-monsoon
season. In the present study we are addressing this issue by analysing observations and a
high-resolution regional ocean-atmosphere coupled model which is able to simulate TCs
and related air-sea interactions over the BoB. In contrast of what has been previously
hypothesized, observational and model analysis reveals that TCs are however stronger
during the pre-monsoon than during the post-monsoon season. We demonstrate that this
behaviour can be attributed to the seasonal atmospheric changes during this two seasons:
the pre-monsoon season indeed exhibits weaker vertical wind shear, increased relative
humidity and reduced stability of the atmosphere column, which ultimately promote
stronger TCs during the pre-monsoon compared to post-monsoon season. Using sensitivity
experiment the impact of air-sea coupling is shown to considerably reduce the number of
TCs during both seasons and to reduce TCs intensity during the pre-monsoon because of
enhanced TC-induced surface cooling. The seasonal change in atmospheric background
state explain the stronger TCs during the pre-monsoon, but the effect is reduced by
stronger air-sea coupling during this season.
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REMOTE AND REGIONAL OCEANIC INFLUENCE DURING SOUTH-WEST
SUMMER MONSOON 2014.
Milind Mujumdar1*, Swapna P.1, M. K. Roxy1, Sabin T.P.1, C. Gnanaseelan1, and R. Krishnan1
1
Indian Institute of Tropical Meteorology, Pune-411 088; [email protected]
The modulation of El Niño and south-west monsoon rainfall during summer months of
2014 was peculiar. The month of July, August and September of 2014 remained relative wet
over south-Asia, as compared to that of June. The month of June 2014 indicated stronger El
Niño conditions over Pacific, while the subsequent modulation of the El Niño was observed
during July, August and September. The Indian Ocean processes seem to have significant
influence on the remote and regional unique SST patterns during 2014 summer monsoon.
The sub-tropical Indian Ocean warming persisted throughout the season. Interestingly, cooccurrence of anomalous warming over the Arabian Sea and eastern equatorial Pacific
during June 2014 subsided during July, August and September months. The Indian Ocean
warming, in particular over Arabian Sea seems to be one of the crucial factor in modulation
of El Niño and Indian summer monsoon rainfall.
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ON THE POSSIBLE CAUSE OF DISTINCT EL NIÑO TYPES IN THE RECENT
DECADES
Jyoti1 J, Swapna1* P, Shamal Marathe1 and K. Ashok1,2
1
Centre for Climate Change Research, Indian Institute of Tropical Meteorology, Pune; [email protected]
2
University of Hyderabad, Hyderabad, India
Distinct El Niño types have been observed in the recent decades with warm anomalies
in the eastern Pacific (Canonical El Niño, EL) and central Pacific (El Niño Modoki, EM).
Among these, a basin wide tropical Pacific (TP) warming is seen during 2009, and El-Niñolike warming during 2014. We carried out data analysis and numerical simulation
experiments to understand the possible cause for different El Niño flavours. The results
reveal that the co-evolution of ocean-atmospheric conditions is critically important.
Stronger (weaker) boreal spring (Mar-May) through summer (June-September) westerly
wind anomalies (WWA), with relatively stronger (weaker) ocean pre-conditioning result in
EL (EM), while stronger ocean preconditioning and weaker WWA lead to basin wide
warming pattern. The strength of the WWA is crucial in determining the strength of the
ocean dynamic response and the thermocline displacements in the Pacific. The study has
important implications for understanding the nature of El Niño in advance.
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INTRASEASONAL TO INTERANNUAL VARIABILITY OF SURFACE LAYER
TEMPERATURE INVERSION IN THE BAY OF BENGAL
Pankajakshan Thadathil1, I. Suresh1, S. Gautham1*,S. Prasanna Kumar1 , Matthieu
Lengaigne2, R.R.Rao3, S. Neetu1 and Y.K. Somayajulu1
1
CSIR-National Institute of Oceanography, Dona Paula, Goa 403004; [email protected]
2
LOCEAN, Institut Pierre Simon Laplace, Paris, France
3
Surface layer temperature inversion (SLTI), a warm layer sandwiched between surface
and subsurface colder waters, have been reported to occur in conjunction with barrier
layers in the three tropical oceans, with potentially commensurable climatic impacts. The
present study take benefit from the Research Moored Array for African-Asian-Australian
Monsoon Analysis and Prediction (RAMA) buoys to improve the description and the
understanding of the SLTI variability in the Bay of Bengal (BoB). SLTI are found to be
considerably more frequent, thicker (~50m) and of larger amplitude (~1°C) at the
northernmost buoy (15°N; 80°E). SLTI at this location shows a distinct seasonal cycle,
appearing sporadically from October onwards and being most frequent (65% of the time)
and of larger amplitude (0.8°C) from December to February. SLTI amplitude and thickness
are virtually unrelated to each other. They both exhibit larger variations at intraseasonal
than at interannual timescales. While surface heat loss and downward penetration of the
surface shortwave radiation below the mixed layer favour the SLTI formation, our analysis
suggest that these mechanism do not account for the SLTI intraseasonal and interannual
variations. Rather, the observed variability is largely explained by horizontal advection of a
cold and freshwater lence over warmer and saltier waters. Finally, SLTI is shown to damp
the amplitude of the winter cooling in the BoB by shedding the possessed heat by SLTI to
the mixed layer through vertical processes of entrainment and diffusion.
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EFFECT OF RIVER DISCHARGE IN SIMULATION OF SEA SURFACE SALINITY
USING ROMS MODEL
K. K. Sandeep1*, Vimlesh Pant1, A. D. Rao1, Arulalan T1
1
Centre for Atmospheric Sciences, Indian Institute of Technology Delhi, New Delhi-110016;
[email protected]
The two divisions of the North Indian Ocean (NIO) basin, namely Arabian sea (AS) and
Bay of Bengal (BoB) exhibit quiet distinct physiochemical properties even though they are
lying in the same latitudinal belt. The large amount of fresh water flux due to river runoff
and excess precipitation over evaporation makes BoB comparatively fresher than the AS
throughout the year. Substantial change in salinity and temperature due to river runoff
results in a change in ambient sea-water density near river mouths in coastal regions. Major
rivers like Ganges, Brahmaputra, Mahanadi, Godavari, Krishna, and Irrawaddy discharge
large amount of freshwater volume to the BoB. In the present study, we simulate the
circulation features of the NIO, particularly in the BoB using a high resolution three
dimensional ocean circulation model, i.e. Regional Ocean Modelling System (ROMS). ROMS
is a free-surface primitive equation model with hydrostatic approximation which
implements the terrain following sigma coordinates in the vertical. The model domain for
BoB confined between 10°N-24°N, 79°E-100°E with 1/8 x 1/8 degree horizontal resolution.
The northern, eastern and western boundaries are closed and the southern boundary is
relaxed to climatology. The model is initialized with annual mean climatology of
temperature and salinity and forced by monthly climatological forcing fields from
Comprehensive Ocean Atmosphere Data Sets (COADS). The model is spun-up for 10 years to
simulate the important oceanographic parameters like temperature, salinity and currents. In
order to examine the effect of river discharge in the BoB, the climatological freshwater
discharge from the Ganges-Brahmaputra (GB) river system was supplied to the ROMS model
using 10th year spun up stage as initial condition. The GB river freshwater discharge was
appropriately distributed in the first four model sigma levels. The river discharge was
supplied to four model grids corresponding to the GB river mouth as a point source of low
salinity to represent the discharge. The model simulated salinity was compared with North
Indian Ocean Atlas (NIOA) salinity climatology. It was observed that the model represents
the freshwater distribution in the BoB better when forced with the river discharge as
compare to without river.
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ROLE OF IOD AND ENSO ON THE INTER-ANNUAL VARIABILITY OF TROPICAL
INDIAN OCEAN
Anju S1,2*, P. Swapna1, K.Ashok1,3, Sandeep1 and Jyoti1
1
Center for Climate Change Research, Indian Institute of Tropical Meteorology, Pune, India
Department of Atmospheric and Space Science, Savitribai Phule Pune University, Pune, India
3
University of Hyderabad, India
2
Indian Ocean Dipole (IOD) is a coupled ocean-atmospheric phenomenon in the
tropical Indian Ocean. The El Niño-Southern Oscillation (ENSO) being the dominant mode of
variability in the tropics, have large impact on the inter-annual variability of the Indian
Ocean. El Niño and IOD are two independent climate modes, many of the IOD events in the
past have co-occurred with El Niño. Recent studies have also identified different El Niño
types based on the spatial pattern of sea surface temperature anomalies in the tropical
Pacific. The role of different El Niño types on the inter-annual variability of Indian Ocean;
especially during IOD events were not understood. An attempt is made in the study to
understand the physical and biological process associated with different IOD events that
occurred independently and during different El Nino Types. Observed data sets, reanalysis
products and an ocean general circulation model with interactive ocean bio-geochemistry is
used for the first time in the Indian Ocean to study the bio-physical feedbacks associated
with different IOD events. Comparisons of the ocean model simulation with remotely
sensed data show that the simulation reasonably reproduces the seasonal cycle and interannual variability of SST and chlorophyll anomalies during IOD events. The preliminary
results of the study show that the effects of pure IOD and co-occurring IOD-ENSO flavors on
the tropical Indian Ocean are entirely different during the IOD evolution. The study also
emphasizes the role of equatorial undercurrents (EUC) in supplying cold subsurface water to
surface and thus enhancing the upwelling in the south eastern equatorial Indian Ocean
during IOD events. The co-occurrence of IOD with different El-Niño types has altered the
circulation of Indian Ocean, formulation of EUC and thus the strength of IOD events. The
bio-physical feedback during IOD events is also addressed in the study.
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RELATIVE ROLE OF EL-NINO SOUTHERN OSCILLATION AND IOD EVENTS ON
MONSOON ACTIVITY OVER INDIA
S. Gopika1*, M. R. Ramesh kumar2
1
Academy of Climate Change Education and Research, KAU, Kerala ; [email protected].
2
The relative influence of the El-Nino,Southern oscillation and Indian Ocean Dipole
(IOD) events on the Indian summer (June-September) monsoon rainfall (ISMR) have been
studied for the period 1950-2007 . In the present study, we investigate the reasons for
annual and interannual variability of ISMR. In order to look into the role of El-Nino on the
monsoon , the SST data over five regions namely eastern pacific (80°W-120°W,10°S-10°N),
central pacific (180°E-140°W,10°S-10°N), western pacific (120°E-160°E,10°S-10°N), western
IOD box (50°E-70°E,10°S-10°N) and eastern IOD box (90°E-110°E,10°S-0°) were studied. All
India rainfall data, homogeneous and macro-regional rainfall dataset, available from IITM,
Pune were also used. The impact of ENSO and IOD conditions on monthly, seasonal, and
yearly changes of ISMR at macro-regional scales were studied . Results shows that El-Nino
indicators NINO1+2 (Far eastern tropical Pacific Ocean) , NINO3 (Eastern tropical Pacific
ocean ), NINO3.4 (Central tropical Pacific Ocean ) and NINO4 (Western tropical Pacific
ocean) shows significant negative correlation with summer monsoon rainfall of india.
During 1950-1969 Enso and IOD events are more independant. From the result it is seen
that after 1969 ENSO and IOD events co-occur, and also it is noticed that the frequent
occurence of posetive phase of IOD events assosiated with El-Nino after 1970. The extent of
El-Nino and SOI correlation with ISMR is higher than that of IOD. But each of the individual
monsoon months, IOD variability have notable effect on ISMR . El-Nino and IOD events
shows a significant negative correlation with rainfall over India while SOI events shows
positive correlation.
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PROCESSES ASSOCIATED WITH THE ARABIAN SEA MINI WARM POOL
FORMATION AND THEIR EPOCHAL CHANGES
Aniket Barphe1, 2,*, C. Gnanaseelan1 and P. Pradeep Kumar2
1
Indian Institute of Tropical Meteorology, Pune- 411 008
Savitribai Phule Pune University, Pune-411007; [email protected]
2
Arabian Sea Mini warm Pool (ASMWP) is the anomalous pool of warm surface water in
the South Eastern Arabian Sea (SEAS) prior to the onset of south-west monsoon. It is found
that the warm pool forms almost all the years but the formation of well-established warm
pool is closely associated with El Nino formation in the Pacific. The warming patterns in the
El Nino developing years and El Nino decaying years are different. The warming during the El
Nino developing year is the response of Arabian Sea to the remote forcing from Pacific
through atmospheric fluxes, whereas the warming during the decaying years are forced by
Indian Ocean dynamics through planetary waves. The monthly HadISST data and NCEPNCAR reanalysis surface wind fields from March to Aug over 40°E-80°E, 10°S-20°N for period
of 1948 to 2006 are used to understand the epochal changes in the ASMWP. The averaged
March-May SST during 1948-2008 shows expansion in region of ASMWP extending southwestward. In El-Nino years Epoch 1 (1948 to 1976) displayed weak warming during MarchMay due to strengthening of mean wind. However June to August experienced warming due
to reduced upwelling along the Somalia coast driven mainly by weaker mean winds. The
weak mean winds are caused by the anomalous winds opposing the mean winds. Epoch 2
(1978 to 2006) is warmer during March-May of the years following El-Nino years (especially
in May). The lead lag correlation between ASMWP and Nino3.4 index further strengthen our
findings.
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INDIAN OCEAN WARMING – ITS EXTENT, AND IMPACT ON THE MONSOON
AND MARINE PRODUCTIVITY
Roxy M. K.1*, K. Ritika1, A. Modi1, P. Terray2, R. Murtugudde3, K. Ashok1,4, B. N. Goswami1,5,
S. Masson2, V. Valsala1, P. Swapna1, S. Prasanna Kumar6 and M. Ravichandran7
1
Indian Institute of Tropical Meteorology, Pune; *[email protected]
3
Sorbonne Universitees, Paris, France University of Maryland, Maryland, USA
4
5
University of Hyderabad, Hyderabad Indian Institute of Science Education and Research, Pune
6
7
Indian National Centre for Ocean Information Services, Hyderabad
2
Indian Ocean warming has captured the attention of a handful of studies in the recent
years, but the cause and effect of this warming has remained enigmatic – until now. In the
current study, we demonstrate that the Indian Ocean has been warming for more than a
century, at a rate and magnitude larger than what was thought before (1.2°C in 100 years).
This intense, monotonous warming turns out to be the largest contributor in-phase with the
global ocean surface warming, with a firm grip on the global climate. We find that the longterm warming trend over the Indian Ocean is due to an increase in the frequency and
magnitude of El Nino events during recent decades, which is likely due to anthropogenic
forcing [Roxy et al, 2014].
Consequences of this excessive warming of Indian Ocean are large, especially on the
physical and biological dynamics over the South Asian domain, and eventually on the socioeconomic livelihood of the surrounding countries. Our analysis with observed data and
model simulations show that the Indian Ocean warming has resulted in weakening the landsea thermal contrast, an essential driver of the monsoon. This has weakened the monsoon
circulation, and in turn reduced the rainfall over a large area extending from Pakistan
through central India to Bangladesh [Roxy et al, 2015]. The excessive warming have also
resulted in the ocean surface stratification over the western Indian Ocean–one of the most
biologically productive regions among the tropical oceans. We find that these increasingly
stratified ocean waters have suppressed the upwelling of nutrients from the subsurface
waters, and have resulted in a reduction of up to 20% in the marine primary production.
Altogether, the Indian Ocean warming is a factor to be vigilant of, while assessing long-term
changes in the monsoon, the marine productivity, and the global climate.
References:
Roxy M. K., K. Ritika, P. Terray, S. Masson, 2014: The curious case of Indian Ocean warming.
J.Climate, 27, 22, 8501-8509.
Roxy M. K., K. Ritika, P. Terray, R. Murutugudde, K. Ashok and B. N. Goswami, 2015: Warm
ocean, weak monsoon. Nature Communications, Revised.
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FLAVOURS IN THE DECAY PHASE OF EL NIÑO AND THE ASSOCIATED
RESPONSE ON MONSOON CIRCULATION AND RAINFALL
H. Sree Harsha1,2*, J. S. Chowdary1, C. Gnanaseelan1, C.V. Naidu2, G. Srinivas1, A Parekh1 and
Prasanth Pillai1
1
Indian Institute of Tropical Meteorology, Pune – 411008
Dept. of MeteorologyandOceanography Andhra University, Andhra Pradesh; [email protected]
2
Impact of developing phase of El Niño on Tropical Indian Ocean (TIO) and Indian
Summer Monsoon (ISM) is well established, whereas influence of El Niño decay phase on
ISM circulation and rainfall is not well understood. In this study we have used 142 years
(1871 to 2012) of Twentieth Century Reanalysis (20CR,V2) monthly mean winds, Extended
Reconstructed Sea Surface Temperature (ERSST) and 112 years (1901 to 2012) of rainfall
data from India meteorological department (IMD) to understand the response of Indian
summer monsoon to different El Nino decays. In general it is known that El Niño in the
Pacific develops during summer season, peaks by winter and decay in next spring. On the
other hand, TIO SST warming as a response to El Niño induced subsidence persists till the
following summer even after the dissipation of El Nino in the Pacific. However, our analysis
revealed that some El Nino’s decay rapidly after the winter and some decay late (in midsummer). Three categories of El Nino decay phases are identified based on their decay
timing (1) early decay (ED; decay before spring), (2) late decay (LD; decay by mid-summer)
and (3) no decay (ND; no significant cooling in the eastern Pacific or developing of next El
Nino by summer). It is found that variations in decay phase of El Nino have different impacts
on ISM circulation and rainfall. During El Nino ED, basin-wide TIO warming does not persist
from winter to summer. Cross-equatorial flow associated with summer monsoon is stronger
and rainfall over most of Indian subcontinent is positive during ED years. Basin-wide TIO
warming persisted until the following summer during El Nino LD years. In response to late
decay, north-easterly wind anomalies over the Bay of Bengal, associated with northwest
Pacific anticyclone, and south-westerly wind anomalies from the Arabian Sea converge over
the Indian subcontinent. This results in positive rainfall over most of the Indian land region.
During El Nino ND years, monsoon circulation is weaker and rainfall is negative over the
Indian subcontinent. This study highlights the importance of El Nino decay variations in
influencing the ISM circulation and rainfall. Further, atmospheric general circulation model
forced with observed SST from 1871-2007 supported our results.
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SUB-SURFACE TEMPERATURE TRENDS IN THE NORTH INDIAN OCEAN AND
OCEAN VERTICAL PROCESSES
Anand babu Amere1, 2*, Anant Parekh1, Fousiya T.S1, G.Bharathi2, C.Gnanaseelan1 and
J.S.Chowdary1
1
Indian Institute of Tropical Meteorology, Pune-411008
Department of Meteorology and Oceanography, Andhra University, Visakhapatnam
*Email: [email protected]
2
North Indian Ocean [10oS to 30oN and 30oE to 110oE] sea surface temperature (SST)
trends known to have strong impact on the climate over the Asia Pacific region. Many
studies have reported increasing trend in SST over the Indian Ocean. This is the first study
exploring the concurrent surface and sub-surface temperature trends in the North Indian
Ocean using observations from Array for Real time Geostrophic Oceanography (ARGO) as
well as multiple ocean models outputs [Ocean reanalysis (ORA), Simple Ocean Data
Assimilation (SODA), Global Ocean Data Assimilation (GODAS)] for the recent two decades
(years 1990 to 2012). The study revealed that there is increasing trend in SST and decreasing
trend in subsurface temperature during first decade (years 1990 to 2001). Whereas no such
trend in SST is evident in the second decade (years 2002 to 2012). On the other hand
increasing trend in subsurface temperature is found in the second decade. The results are
consistent in both observations and reanalysis data sets. Detailed analysis revealed that the
upper ocean vertical gradient in density display negative (positive) trend during the second
(first) decade leading to weak (strong ) buoyancy. This supports more vertical mixing in the
second decade. In addition to that, the vertical shear of horizontal current increased in the
recent decade. Thus vertical mixing due to weakening buoyancy and increasing current
shear is responsible for the observed surface warming trend in the recent decade.
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THE STRUCTURE OF INDIAN OCEAN MERIDIONAL OVERTURNING IN OCEAN
REANALYSIS DATASETS AND AN OGCM
S Rahul, C Gnanaseelan*
Indian Institute of Tropical Meteorology, Pune, India; [email protected]
The tropical oceans, on an annual average, receive net heat input from atmosphere,
which has to be transported polewards to maintain surface heat balance. This is achieved by
Meridional Overturning Circulation (MOC). The tropical shallow branch of the MOC
transports warm tropical waters to the subtropics where they exchange the net heat gained
in the tropics back to the atmosphere, sinks down and is transported back to deep tropics
and is replenished to surface by net upwelling. As MOC plays a major role in the surface
heat balance, understanding the MOC structure is crucial for understanding the surface heat
balance.
The Indian Ocean (IO) currents from reanalysis data sets and an OGCM are
decomposed to separate the rotational and divergent components of the horizontal
currents using Helmholtz decomposition. Meridional overturning stream functions (MOS)
are derived from zonally integrated divergent currents. This methodology helps to visualize
the MOC structure south of 5oS in IO which was not otherwise achievable because of
divergence created by Indonesian through flow transport. The mean MOS in ocean
reanalysis data sets displays the conventional structure of IO MOC, i.e. a shallow south
equatorial cell and a deep cross equatorial cell. The OGCM displays a deeper MOC transport
compared to the reanalysis data sets. EOF analysis of MOS in reanalysis data sets showed
that inter-annual variability in IO MOC structure is confined to the upper 1500m. A long
term trend is superimposed on this variability, but is in opposite direction in the two datasets considered in this study.
The variability of MOC is coherent with the variability of zonal circulation in
reanalysis data sets. The differences in mean MOC structure and variability within the
reanalysis data sets and the OGCM suggests that the closure of energy budget (which is
absent in reanalysis) can significantly affect the simulated MOC structure and strength.
91
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MESO-SCALE EDDIES IN THE NORTH INDIAN OCEAN AND THEIR
PROPAGATION PATHWAYS
T.N. Shyni and P.V. Hareesh Kumar
Naval physical & Oceanographic Laboratory, Kochi-21; [email protected]
Meso-scale eddies and associated variability is a major component of oceanographic
research today; since these features play an active role in the general ocean circulation,
distribution of seawater properties, mixed and sonic layer variability and acoustic
propagation. The North Indian Ocean (NIO), one of the most dynamic regions among the
world oceans, is famous for the occurrence of meso-scale eddies of varying dimensions.
Despite the importance, the eddy activities in the NIO have not been substantially
described. Therefore, in this study the eddy characteristics viz., lifespan, amplitude,
vorticity, spatial dimension, propagation speed and their pathways in the NIO are examined.
The eddies are detected and tracked from 18 years of sea level anomaly data (years 19932010) following Isern-Fontanet parameter (Q) and flow geometry based algorithm. The
analysis revealed 2123 meso-scale eddies having life span of more than 4 weeks over a
period of 18 years; moreover is a slight dominance of anti-cyclonic eddies over cyclonic
eddies. Majority of eddies are having life span between 4-8 weeks and the eddy count drop
off rapidly with increasing life time. It is also noticed that the number of eddies formed in
the Arabian Sea is significantly high compared to that in the Bay of Bengal. The propagation
pathways of these eddies exhibit a westward movement with slight north-south deflection
and got dissipated on the western boundaries of the ocean.
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PHYSICAL PROCESSES CONTROLLING MIXED LAYER VARIABILITY IN THE
NORTHERN INDIAN OCEAN
Jayu Narvekar* and S. Prasanna Kumar
CSIR-National Institute of Oceanography Dona-Paula, Goa 403 004, India; [email protected]
Seasonal mixed layer variability and processes controlling it was studied in the
northern Indian Ocean using in situ and remote sensing data. Compared to zonal variability,
meridional variability is more in the Arabian Sea and the Bay of Bengal, while reverse is the
case in the equatorial Indian Ocean. Hence, three areas in the northern Indian Ocean were
considered to understand the seasonal variability of mixed layer depth (MLD) in the central
Arabian Sea (equator to 25oN and 62oE to 66oE), central Bay of Bengal (4oN to 20oN and 87oE
to 91oE) and equatorial Indian Ocean (5o N and 5oS and 40oE and 100oE). Mixed layer
showed a strong semi-annual variability in the Arabian Sea and the Bay of Bengal with deep
mixed layer during summer and winter and shallow mixed layer during spring and fall
intermonsoons. During summer MLD in the Arabian Sea was controlled by Ekman dynamics
associated with the Findlater Jet. Under the influence of the cyclonic wind-stress curl the
MLD in the northern Arabian Sea shoaled while the anti-cyclonic wind-stress curl deepened
the MLD in the southern Arabian Sea. In contrast, the MLD in the northern Bay of Bengal
during summer was not regulated by the Ekman dynamics, but was controlled by the fresh
water flux (both oceanic precipitation and river discharge), which remained very shallow
(~10 m). In the southern Bay, however, wind forcing along with advection of high salinity
waters from the Arabian Sea controlled the MLD. During winter, cooling and convective
mixing regulated MLD in the northern Arabian Sea, while in the south Rossby waves
influenced the MLD. In the northern Bay of Bengal, the perennial presence of the low
salinity waters stratified the upper layers and the wind forcing did not significantly influence
MLD. In the southern Bay, the low stratification during winter allows greater wind-driven
mixing which leads to deepening of mixed layer. During spring and fall intermonsoons, the
weak winds along with strong incoming solar radiation lead to the formation of thin, warm
and stratified mixed layer in both the Arabian Sea and the Bay of Bengal. In contrast to the
semi-annual variability seen in the Arabian Sea and the Bay of Bengal, in the equatorial
region the MLD showed an annual signal, with deep mixed layer during June-September and
shallow mixed layer from October to May. The deep MLD during summer (June-September)
was due to the combined effect of strong winds and low net heat flux while the shallow
MLD in winter was driven by the weak winds and negative E-P. The presentation also
discusses the role of inter-basin advection of high and low salinity waters as well as
propagating waves on mixed layer variability.
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22-24 March 2015
VARIABILITY AND TRENDS IN THE TROPICAL INDIAN OCEAN SEA SURFACE
SALINITY, IN A CHANGING CLIMATE
Vivek Shilimkar 1*, M. K. Roxy2
1
Department of Atmospheric and Space Sciences, Savitribai Phule Pune University, Pune;
[email protected]
2
Indian Institute of Tropical Meteorology, Pune.
Variability and trend in tropical Indian Ocean sea surface salinity (SSS) during boreal
summer is studied using SODA reanalysis and CMIP5 historical simulations for the past six
decades. The current study finds that SSS over the Indian Ocean exhibits a dipole-like trend.
Extended analysis of the physical parameters show that the dipole like trend in salinity is
driven by similar trends in SST and precipitation. Similar to Cai et al. (2014), the current
study also indicate a skewness towards positive dipole events with increasing SST gradient
between west and southeastern Indian Ocean. Such a trend has resulted in enhanced
convective precipitation over the west and suppressed convection over the southeast. This
has resulted in associated trends in salinity also. A possible consequence of such a trend in
salinity is decreased southward transport of water, which is evident from the observations.
The changes in climate that could have caused by this trend in salinity are examined with
model experiments.
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IMPACT OF AQUARIUS SEA SURFACE SALINITY ASSIMILATION IN IMPROVING
THE OCEAN STATE
Vivek .S1,2*, P. Sreenivas1, C. Gnanaseelan1 and K. V. S. R. Prasad2
1
Indian Institute of Tropical Meteorology, Pune; *email: [email protected]
2
Dept. of Meteorology & Oceanography, Andhra University, Visakhapatnam
Seasonal and Extended range prediction of Indian summer monsoon has been a
challenging task for meteorological communities. It is a well established fact that accurate
representation of ocean state is very essential for better seasonal as well as short term
weather forecast. Any inaccuracy in the representation of upper ocean thermal structure in
the ocean initial state will lead to drastic errors in coupled model forecast. The data
assimilation techniques have promising role in achieving an accurate ocean state in the
context of recent advances in ocean and atmospheric observational networks. The structure
of ocean salinity controls the density field and thereby playing a major role in influencing
the ocean dynamics. It has been a challenging task to understand the strong intra-seasonal
and inter-annual variability of salinity structure in the regions of large fresh water discharge
and high precipitation such as Bay of Bengal. Even the well organized assimilation
schemes/models have limitations in producing accurate salinity analysis due to the lack of
significant salinity observations (both spatially and temporally). Recent advancement in
satellite technology has made possible the measurement of sea surface salinity (SSS) with
unprecedented spatio-temporal coverage. Aquarius is the recent operational mission which
measures the global SSS since 2011. We assimilated Aquarius SSS in the Global Ocean Data
Assimilation (GODAS) for the period 2011 to 2014. GODAS is the assimilation module for
MOM4 (ocean component of CFS, the forecast model used in India and many other
countries). The assimilation scheme in GODAS is 3DVAR. The present study addresses the
impact of assimilating Aquarius SSS in improving the ocean analysis and the intra-seasonal
and inter-annual variability of salinity in the key regions such as Bay of Bengal. The results
are validated with ECCO2 model and in-situ RAMA buoy observations. The results are
discussed in this study.
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DYNAMICAL LINK BETWEEN TROPICAL INDIAN OCEAN AND CYCLONES
P. Sreenivas1*, C. Gnanaseelan1, J.S. Chowdary1 and K.V.S.R. Prasad2
1
Indian Institute of Tropical meteorology, Pune – 411008; [email protected]
2
Dept. of Meteorology & Oceanography, Andhra University - 530008.
The socio-economic impact of tropical cyclones is considerable, depending on the
intensity and region of landfall, the cyclones give rise to copious rainfall, major inland
flooding which often causes damage and loss of life in the coastal areas of the Indian
subcontinent, Bangladesh, and Myanmar. The present study examines the role of ocean
surface in cyclogenesis and vice-versa i.e. the role of cyclones on the ocean surface
variability in the Indian Ocean. The analysis of cyclogenesis characteristics in the Bay of
Bengal over the past 65 years revealed that the active (suppressed) phases of cyclogenesis
are coinciding with the downwelling (upwelling) planetary waves which influence the
cyclone heat potential by altering the thermocline depth. Also the interannual variability of
cyclogenesis (number of cyclones) is varying in correlation with propagating planetary
waves. We also examined the role of surface ocean processes on the life cycle of severe
cyclonic storm “Jal” as a case study.
The above findings infers the impact of surface ocean processes on cyclogenesis and
their propagation; in the latter section of this study, we addressed the key issue of role of
cyclones on large scale dynamics in the Indian ocean by conducting a thorough examination
of Tropical cyclones (TC) and equatorial dynamics. The equatorial Indian ocean is
characterized by a strong narrow currents often called as Wyrtki jets (WJ). These jets peak
during November and play a vital role in the energy and mass transport in the tropical
Indian Ocean (TIO). Maximum number of TCs is observed over TIO during November with
longer than normal life span (8–15 days). These TCs enhance equatorial westerly winds
(surface) and amplify monthly mean WJs (both at surface and subsurface) by 0.4 ms-1
(anomalies exceed 0.7 ms-1 during TC), which is about half of the climatological amplitude.
Intensified WJs increase the heat content of eastern TIO and modulate air-sea interaction. It
is also shown that movement of TCs is mainly responsible for the westward phase
propagation of WJs, a previously unexplored mechanism. These features are evident in
ECCO2 simulations as well.
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ASSIMILATION OF ALTIMETRY DERIVED TEMPERATURE AND SALINITY IN
GODAS AND ITS IMPACT ON MONSOON PREDICTION
P. Sreenivas, N. Pavan Kumar, R. Kakatkar and C. Gnanaseelan
Indian Institute of Tropical Meteorology, Pashan, Pune. 411008; [email protected]
SARAL-ALTIKA is one of the recent among the series of satellites observing ocean
surface anomalies. It has extremely good spatial coverage and reasonable temporal
resolution. The raw along track data of SARAL-ALTIKA obtained from MOSDAC is first
gridded using in-house developed algorithm and subsequently sea surface height anomalies
(SSHA) data sets are extracted. Observed SSHA and ARGO data are combined to derive
synthetic profiles of Temperature and Salinity using multivariate empirical orthogonal
function (EOF) technique. The multi-mission altimetry (TOPEX/POSIEDON, JASON 1 & 2)
SSHA has been utilised for training purpose and SARAL data has been utilised for real time
derivation of synthetic profiles.
The SSHA derived synthetic profiles of temperature and salinity are assimilated in the
Global Ocean Data Assimilation (GODAS), the assimilation module for ocean component of
NCEP Climate Forecast System, CFSv2, which is the operational seasonal forecast model
used in many countries including India. The assimilation scheme in GODAS is 3DVAR. The
accurate representation of SST is an important factor for an accurate forecast of monsoon.
Using synthetic profiles, assimilation is done to generate best estimate of ocean state as
initial condition for CFS to understand the impact of altimeter assimilation on the Indian
summer monsoon forecast and the associated large scale circulation changes.
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EQUATORIAL INDIAN OCEAN SUBSURFACE CURRENT VARIABILITY IN AN
OCEAN GENERAL CIRCULATION MODEL AND ITS IMPACT ON REGIONAL
CLIMATE.
Aditi Deshpande* and C. Gnanaseelan
1
Indian Institute of Tropical Meteorology,Pune; [email protected]
The vertical structure and the subsurface current variability over the equatorial Indian
Ocean have not been addressed in detail due to lack of observational data. In this study, we
have focused on the vertical structure of Wyrtki jets and the equatorial Indian Ocean
subsurface current variability in an ocean general circulation model (OGCM). Empirical
Orthogonal Function (EOF) analysis of depth averaged (80-120mts) subsurface zonal
currents at the equator reveal that the first mode of variability is associated with Indian
Ocean Dipole (IOD). However, the first principal component shows strong peaks during
some IOD years, and no significant peaks during others. Based on the classification given in
Deshpande et al. (2014), the IOD years were further classified as strong IOD years and weak
IOD years. The evolution of the equatorial undercurrent during these years was studied
using a high resolution OGCM. It is found that the equatorial undercurrent evolves
consistently during the strong IOD years and it is much stronger than the climatological or
the undercurrent observed during the weak IOD years. The evolution of undercurrent is not
very consistent during weak IOD years with a well defined under current visible only in the
peak phase of IOD. The undercurrent supports the intensification of upwelling in the eastern
box of IOD (90°E-110°E, 10°S-Equator). Since, the strong undercurrent during strong IOD
years is well defined since the evolution of IOD, the sea surface temperature (SST)
anomalies and thermocline anomalies evolve coherently. There is a strong thermocline-SST
coupling during strong IOD years, which is absent during weak IOD years. The strong IOD
years are found to co-occur with significant enhancement of monsoon circulation over north
Indian Ocean and positive rainfall anomalies over India. During weak years, no such
significant anomalies are seen in monsoon rainfall or circulation.
References:
A.Deshpande, Chowdary J.S. and Gnanaseelan C., (2014) Role of thermocline–SST coupling
in the evolution of IOD events and regional impacts. Climate Dynamics doi:10.1007/s00382013-1879-5.
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INTER-ANNUAL VARIABILITY OF UPPER OCEAN STRATIFICATION IN BAY OF
BENGAL: OBSERVATIONAL AND MODELING ASPECTS
T.S. Fousiya1*, Anant Parekh1 and C. Gnanaseelan1
1
Indian Institute of Tropical Meteorology,Pune; [email protected]
This study presents the mean annual cycle and interannual variability of stratification
in Bay of Bengal (BoB) from Global Ocean Data Assimilation System (GODAS) and
observations during 2003-2011. Annual cycle of stratification in BoB displays a bimodal
distribution with maxima during spring and fall (spring peak due to high insolation and weak
winds, fall peak due to strong surface fresh water forcing) and is in phase with SST cycle. The
mean stratification and its interannual variability in BoB are weaker in GODAS than
observation even though it has more fresh water flux. Further analysis based on recent insitu observations reveals that enhanced vertical mixing in GODAS is partly due to improper
critical Richardson number for BoB. This supported strong unrealistic mixing in GODAS to an
extent even excess fresh water flux at the surface could not maintain stratification. El Niño
(La Niña) years are characterized by less (more) stratification in BoB due to weaker
(stronger) fresh water flux, which are misrepresented in GODAS. As stratification modulates
air-sea interaction over BoB especially during El Niño or La Niña years, such
misrepresentation of stratification may lead to improper coupling. As GODAS is used to
initialize Coupled Forecasting System for seasonal prediction of Asian monsoon, proper
representation of stratification is essential. This study concludes that representation of
mixing processes and horizontal advection in GODAS need improvement as they primarily
determine the stratification and its interannual variability.
References:
Shenoi, S. S. C., Shankar, D., and Shetye, S. R.: Differences in heat budgets of the near
surface Arabian Sea and Bay of Bengal: Implications for the summer monsoon, J. Geophys.
Res., 2002, 107(C6), 3052.
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A NEW MODE OF VARIABILITY IN THE TROPICAL INDIAN OCEAN SUBSURFACE
TEMPERATURE AND ITS CLIMATIC IMPACTS
C. Gnanaseelan* and Sayantani Ojha
The first two leading modes of interannual variability of sea surface temperature in
the Tropical Indian Ocean (TIO) are governed by El Niño Southern Oscillation (ENSO) and
Indian Ocean Dipole (IOD) respectively. TIO subsurface however does not co-vary with the
surface. The patterns of the first mode of TIO subsurface temperature variability and their
vertical structure are found to closely resemble the patterns of IOD and El Niño cooccurrence years. These co-occurrence years are characterized by a north-south subsurface
dipole rather than a conventional IOD forced east-west dipole (Sayantani and Gnanaseelan,
2014). This subsurface dipole is forced by wind stress curl anomalies, driven mainly by
meridional shear in the zonal wind anomalies. A new subsurface dipole index (SDI) has been
defined in this study to quantify the intensity of the north-south dipole mode. The SDI peaks
during December to February (DJF), a season after the Dipole Mode Index peaks. It is found
that this subsurface north-south dipole is a manifestation of the internal mode of variability
of the Indian Ocean forced by IOD but modulated by Pacific forcing. This mode has strong
correlation with the SST evolution in the TIO and summer monsoon precipitation over the
Indian subcontinent. The thermocline SST interaction associated with this mode plays an
important role in the basin scale TIO warming and cooling associated respectively with El
Niño or La Niña in the Pacific. It also plays a dominant role in the formation and propagation
characteristics of Madden Julian Oscillation. Most of the current coupled models including
CMIP models capture this leading mode of subsurface variability. The persistence of this
north south dipole pattern for two to three seasons alter the mean thermal structure of the
tropical Indian Ocean, which in turn has great impact on the regional climate.
Reference:
O. Sayantani and C. Gnanaseelan, ‘Tropical Indian Ocean subsurface temperature variability
and the forcing mechanisms’, Climate Dynamics, 2014, DOI 10.1007/s00382-014-2379-y
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INTER COMPARISON OF DIFFERENT OCEAN MODELS OVER THE TROPICAL
INDIAN OCEAN
Ananya Karmakar*, Anant Parekh, Jasti Chowdary, and C. Gnanaseelan
Indian Institute of Tropical Meteorology (IITM), Pune- 411 008; [email protected]
This study presents the inter comparison of the physical parameters of Tropical Indian
Ocean (TIO) in different ocean models like Modular Ocean Model v3 (MOMv3), Modular
Ocean Model v4 (MOMv4), Nucleus for European Modelling of the Ocean (NEMO) and
Parallel Ocean Physics (POP). These models are used to produce ocean reanalysis Global
Ocean Data Assimilation System (GODAS), Geophysical Fluid Dynamics Laboratory (GFDL),
Ocean Reanalysis System 4 (ORAS4), and Simple Ocean Data Assimilation (SODA POP)
respectively. Recent studies have reported that many ocean models have larger discrepancy
in simulating the surface and subsurface features of Indian Ocean. Present study mainly
analyzes the long term mean vertical structure of temperature, salinity and currents in
different models/analysis compared to observations (WOA-2013, OSCAR etc). All these
models/analysis have warm sea surface temperature (SST) bias (0.05 - 0.25oC) and negative
bias in sea surface salinity (SSS) (-0.05 to -0.25 psu). Almost all models have deeper mixed
layer (especially GODAS has largest bias) with respect to observation. GODAS has large bias
in MLD than GFDL even though both models are using more or less same forcing and
physics. Furthermore GODAS has zonally asymmetric mixed layer depth bias along 70o E, the
associated positive zonal density gradient leads to more vertical shear in the meridional
current compared to other models. Similar analysis is carried out for the mean current of
Tropical Indian Ocean (TIO). In contrast to the observation, GODAS and GFDL revealed mean
westward current over the Equatorial Indian Ocean (EIO) in JJAS. Consistent with the
positive MLD bias, the upper ocean currents are underestimated in all the models compared
to SODA. This study shows that most of the models have bias within 100-200 m depths in all
physical parameters highly questioning the parameterization of upper ocean physics and
dynamics in these models.
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IMPACT OF PROLONGED ENSO EVENTS ON TROPICAL INDIAN OCEAN IN THE
COUPLED MODEL CFSv2 AND OBSERVATIONS
P. Singh*, J.S. Chowdary and C. Gnanaseelan
ENSO is coupled air-sea interaction event which is highly variable in interannual time
scale i.e. 1.5 to 8 years. Protracted events are those events in which SST anomalies in the
eastern-central Pacific persists for more than 2 years. These protracted ENSO events are the
resultant of interactions between quasi-biannual low frequency and quasi-decadal signals in
the climate system. In this study we used 50 years of observations and coupled model CFSv2
simulations to study the impact of these events on Tropical Indian Ocean. It is found in both
the observation and model simulations that protracted La Nina events occur more
frequently than protracted El Nino events. It is also observed that during the transition
period i.e. from El Nino to La Nina and vice versa, the western Tropical Indian Ocean is
impacted more than the eastern tropical Indian Ocean during June to September (JJAS). The
transitions from long lived La Nina leave strong gradient in SST anomalies over the tropical
Indian Ocean favouring more convection over the eastern equatorial Indian Ocean. This can
significantly affect the monsoon circulation and precipitation.
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PHYSICO-CHEMICAL PROPERTIES AND STABLE OXYGEN ISOTOPIC (Δ18O)
VARIATIONS OF SEAWATER, ALONG THE CONTINENTAL SHELF DURING POST
NE AND SW MONSOON PERIODS, SOUTH EAST COAST, INDIA.
Nisha.V1* and H. Achyuthan2
1
Post Doctoral Fellow, PRL, Ahmedabad; [email protected]
Dept. of Geology, Anna University, Chennai; [email protected]
2
Continental shelf studies are important in order to understand the physicochemical
properties of sea water as well as biogeochemical systems existing in the marine
environment. Lying within the tropical zone the east coast Tamilnadu receives strong
monsoonal rains and hence any variation in the intensity and amount of precipitation would
reflect in the seawater characteristics along the continental shelf. The present study
quantifies the spatial and vertical heterogeneity in the distribution of physico-chemical
parameters and stable Oxygen isotopic values (δ18O) of seawater during the 2009 post
North East (NE) and South West (SW) monsoon periods along the continental shelf from
Chennai to Nagapattinam, East Coast, Tamilnadu. For this purpose, six sampling sites were
selected for collecting seawater samples spatially and vertically, based on the seawater
column thickness along the continental shelf such as 50 m, 75 m, 100 m and 150 m
extending from Chennai to Nagapattinam, East Coast, Tamilnadu. Variations in δ18O, salinity
and temperature data of the seawater samples along the continental shelf were studied to
understand the influence of monsoonal (post NE and SW) precipitation and evaporation
patterns as these parameters are affected by the fractionation and mixing processes.
Thermocline in the seawater column existed between 30 m to 60 m depth during post NE
monsoon period while during SW monsoon, it was observed between 20 m and 40 m.
Halocline existed between 40 m and 70 m during both the monsoon periods. The oxycline
was recorded between 40 m to 60 m in all the stations during the post NE monsoon
whereas during SW monsoon, it was shallower between 30 m and 50 m depth. The
distribution of dissolved oxygen content showed marked variations during both the
monsoons, in the surface waters and at various depths which is due to the vertical mixing of
riverine inputs along the shallow waters of the continental shelf. The observed values of
nutrients (NO3, NO2, NH4 and PO4) in seawater for the post NE monsoon period are low
compared to the SW monsoon period. Contour lines plotted indicate seasonal and spatial
variations in physico-chemical parameters along the continental shelf of the east coast of
India. These observations are also reflected by the stable isotope oxygen data. Salinity,
temperature and stable oxygen isotope reconstruction showed that the parameters
increased towards the central regions of the coastal stretch, especially along Tarangampadi
and Chidambaram. The inferences drawn from the various physico-chemical parameters of
water samples at various seawater column depths reveals that during both the monsoon
periods (post NE and SW), the salinity, temperature, oxygen and nutrients distinctly varied
with depth towards the deeper seawater column following the continental shelf. This is
caused due to the enhanced contribution from the easterly flowing rivers and distributaries
(Cauvery river), strong influence of precipitation over the East Coast Tamilnadu, seawater
mixing processes, industrial influxes and various anthropogenic influences.
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DECADAL VARIABILITY IN THE TROPICAL INDO PACIFIC OCEAN AND ITS
IMPACT ON INDIAN SUMMER MONSOON
Abhishek Savita1, 2*, C. Gnanaseelan1, S. Rahul1
1
2
Indian Insttute of Tehnology, Kharagpur
In this study we examined the relation between decadal sea level and walker
circulation change over 1993-2006 in the Indo-Pacific region. Satellite observation of sea
surface height and wind stress curl showed a large scale decadal variability in the Indo
Pacific region at the end of the 20th century (Lee and McPhaden, 2008). The major feature
of the decadal change is the rising SSH in the western tropical pacific and southeast Indian
Ocean during 1993-2000 period and the decreasing SSH for the 2000-2006. We have defined
an index to quantify the strength of the variability. The walker circulation shows increasing
trend in convection over the central and northern India during 1993-2000 and on the other
hand strong subsidence is seen during 2000-2006. On the contrary southern peninsular
India showed trends of subsidence during 1993 to 2000 and convection during 2000 to
2006. The precipitation over the Indian land region also displayed similar patterns. Strong
upper level divergence is seen over the western Pacific during 1993 to 2006 inducing surface
convergence. On the other hand western Pacific displayed strong subsidence during 2000 to
2006. This study speculates the role of decadal Indo Pacific variability in causing decadal
variability in Indian summer monsoon rainfall.
The Walker circulation shows due to the variation in the wind stress in the equatorial
Pacific and Indian Ocean region. More variability is seen in the south West Indian Ocean,
east equatorial Indian Ocean, western part of Australia, west pacific, north west pacific and
south west pacific. The variability in the East equatorial Indian Ocean and Western Australia
related to the North West pacific variability through Indian Ocean through flow. We also
used the mom4p1 model simulate these variability and compare with the observation data
sets.
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DYNAMICS OF SUMMER MONSOON OCEANIC EDDIES IN BAY OF BENGAL
AND ITS EFFECT ON ATMOSPHERE
Saurabh Rathore1,2*, Anant Parekh1, Mihir Kumar Dash2
1
Indian Institute of Tropical Metrology, Pune
Indian Institute of Technology, Kharagpur; [email protected]
2
Meso-scale eddies form a distinctive and dynamic feature of ocean circulation and has
a profound impact on the large scale flux of heat, salt, momentum in the ocean-atmosphere
system. Oceanic eddies are circulating water bodies, and anticyclonic (cyclonic) eddies are
associated with high (low) sea surface height and deeper (shallow) thermocline, transport
heat and salt from one water mass to another, modifying thermohaline structure, transport
and dispersal of dissolved substances and nutrients and affect cyclogenesis. Bay of Bengal
(BoB) eddies plays role in the productivity of the bay and the sediment transportation.
Meso-scale eddies of BoB affect the cyclogenesis and the intensity of mature cyclone, as the
cyclone pass over from the cyclonic eddy its intensity decreases because of cold SST where
as its intensity increases as it pass over the anticyclonic eddy due to warm SST. This study is
to explore the role of meso-scale features on the dynamic and thermodynamic response of
the BoB and its effect on the overlying atmosphere during the summer monsoon period
(JJAS).
Okubo-Weiss parameter (OWP) is used to identify the meso-scale oceanic eddies.
OWP = Ss2 + Sn2 – ω2. Where Ss is shear stress, Sn is normal stress and ω is vorticity. The eddy
core is defined as an interconnected region of negative OWP (W < –W0), where W0 = 0.2σw
(W0 is threshold value and σw is spatial standard deviation of W for study region)
For this study we used Sea Level Anomaly (SLA) data for the period of 1993-2013 from
AVISO/SSALTO DUACS and temperature and salinity profile data from the Argo for the
period of 2003-2012. We studied MLD and D20 signature over the eddies location. Wind
stress curl over the region is estimated from ERA-Interim data from 1993-2010. For
chlorophyll data we use Goddard Earth Sciences Data chlorophyll-a concentration from
2002-2012. In our study, we identified the eddies present in the BoB (790E-1000E, 50N230N) during JJAS for the period of 1993-2013 by using OWP. We found two cyclonic eddies
C1 and C2 centered at 85.70E, 17.90N & 83.70E, 8.70N respectively and one anticyclonic
eddy, A1 centered at 84.20E; 14.30N sandwiched between these two cyclonic eddies. At the
center of C1 and C2 the measured SLA values are -0.07 m and -0.05 m, whereas the
measured SLA values at the center of A1 is 0.06 m. The value of relative vorticity
(geostrophic vorticty) at the center of C1, C2 and A1 is 4.56×10-6 s-1, 2.308×10-6 s-1,
1.484×10-6 s-1 respectively. The value of OWP for C1 is 3.5×10-11 s- for C2 and A1 are 8.0×1011 -2
s and 3.9×10-11 s-2 respectively. We also studied mixed layer depth (MLD) and
thermocline depth (D20) signatures of these eddies and results are consistent with the
theory proposed for eddies. As relatively shallow MLD of 17.7 m and 22.3 m and D20 of
109.6 m and 98.7 m are observed for C1 and C2 respectively whereas relatively deeper MLD
of 29.8 m and D20 of 122.8 m are observed in case of A1. Eddy Kinetic Energy (EKE) is
computed over the area of observed eddies from SLA data from 1993-2013, which showed
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the presence of meso-scale activity over identified eddy regions and having fair signal of
4598 cm2/s2,6546 cm2/s2, 5523 cm2/s2 for C1, C2, A1 respectively. In this context wind stress
curl over the region was also analyzed for JJAS period and we found that the signature of
high rotational component of stress is one of the reasons for generation of eddies. Furthermore from the analysis of chlorophyll concentration data, it is clearly shown that cyclonic
eddies are fruitful because they bring the nutrients on surface from sub-surface. In our
analysis we found the chlorophyll concentration as 0.27 mg/m3, 0.25 mg/m3 and 0.13
mg/m3 over C1, C2 and A1 respectively. Hence cyclonic eddies (up-welling) are more
productive as compare to anticyclonic eddies (down-welling). Further expanding the study
in the direction to analyze the effect of these meso-scale features to overlying atmosphere,
composite of temperature and water vapour mixing ratio anomaly profile is analyzed over
cyclonic and anticyclonic eddies. By this analysis we found that cyclonic eddies converge the
moisture and make the atmosphere warmer and vice versa happens in case of anticyclonic
eddies.
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VARIABILITY OF ATMOSPHERIC REFRACTIVE INDEX STRUCTURE PARAMETER
(CN2) – A CASE STUDY AND IT’S PREDICTION USING METEOROLOGICAL DATA
G Nageswara Rao* and Amit Pratap
Center for High Energy Systems and Sciences, DRDO, Hyderabad-500069; [email protected]
There are numerous atmospheric effects that can significantly impact the
performance of high power laser systems. Atmospheric turbulence and meteorological
visibility (clouds, dust, fog and aerosols) reduces the laser power density at target.
Propagation through atmospheric turbulence results in beam spreading, wandering, and in
case of strong turbulence, beam will break up into many smaller beams (scintillation). The
most important parameter that characterizes the effects of turbulence is the atmospheric
refractive index structure parameter. The atmospheric turbulence can be defined by the
strength of the fluctuations in the refractive-index, represented by refractive-index
structure parameter (Cn2, units-m-2/3). Many authors have tried to predict the behaviour of
the refractive-index structure parameter, and various models have been proposed (Sadot &
Kopeika, 1992).
However, these models developed for different atmospheric conditions which may
not be directly applicable for Indian climatic scenario. Hence, a new empirical model has to
be developed for Indian atmospheric conditions. In order to do the same, data collected by
scintillometer (BLS 900) installed at Shaadnagar, Hyderabad with a path length of 671m was
utilized. Efforts have also been made to empirically model the Cn2 using meteorological
parameters. The data spans from 15-30 April 2013 with a time interval of 15min.
Results showed that Cn2 had strong diurnal and semi-diurnal variability. Maximum
standard deviation of Cn2 was observed at noon time. The meteorological parameters viz.,
temperature, relative humidity and wind speed also showed diurnal pattern. The correlation
values of temperature, humidity and wind speed against Cn2 were 0.71, -0.62 and 0.68
respectively. An empirical model (multi-polynomial type) has been developed for Cn2 with a
regression coefficient of 0.5 and correlation coefficient of 0.71. However, there was
difference in the value at noon. Using this observed and predicted Cn2 values, laser
parameters viz., short term radius, long term radius and beam wander were also computed.
In summary, Cn2 values can be predicted with reasonable accuracy using
meteorological data. However, prediction of Cn2 is difficult during noon time because of its
high standard deviation. The accuracy of the prediction can be improved by including more
and more data.
Acknowledgements: Authors are thankful to Director, CHESS for providing the motivation
and encouragement to carry out this study. Authors are grateful to Director, NRSC,
Hyderabad for providing the scintillometer data.
References:
Sadot D and Kopeika NS (1992), Forecasting optical turbulence strength on the basis of
macroscale meteorology and aerosols: models and validation, Opt. Engg., Vo. 31, No. 2.
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22-24 March 2015
EPOCHAL CHANGES IN THE DOMINANT SUBSURFACE MODE OF TROPICAL
INDIAN OCEAN
Ojha Sayantani* and C. Gnanaseelan
Indian Institute of tropical Meteorology, Pune-411008; [email protected]
The patterns of the first mode of TIO subsurface temperature variability and their
vertical structure are found to closely resemble the patterns of IOD and El Niño cooccurrence years. These co-occurrence years are characterized by a north–south subsurface
dipole rather than a conventional IOD forced east–west dipole. The first mode of variability
of depth of 20°C isotherm and 100 meter temperature shows a northern cooling and
southern warming over the TIO during the co-occurrence years. The intensity of subsurface
dipole mode is quantified by using subsurface dipole index (SDI) which is defined as the
difference in d20 anomalies between the regions 60°E–90°E, 15°S–5°S and 70°E–100°E, 5°S–
10°N. This subsurface dipole is forced by wind stress curl anomalies, driven mainly by
meridional shear in the zonal wind anomalies. The subsurface temperature variability and its
north-south dipole pattern show differences in the pre and post climate shift period. The
subsurface variability has been examined before and after 1976-1977 which is known as the
period when the characteristics of ENSO evolution and its related teleconnection have
revealed major changes. The southern TIO warming is stronger and extended over a
broader region in post-76 period. The seasonal variability also shows differences in spatial
pattern. In post-76 period during all the three seasons (SON, MAM and DJF) the southern
warming is located mainly in the central TIO whereas in the pre-76 it can be seen in the
western TIO. In the recent epoch the Arabian Sea is warmer in all the three seasons which is
not the case in the pre-76. The forcing mechanism also shows prominent differences in the
two cases. The meridional wind shear is stronger in the recent epoch which causes strong
anticyclonic wind stress curl. The anticyclonic curl induces downwelling Rossby wave in the
southern TIO which propagates westward and keeps the western basin warm. This wind
stress curl and associated wave propagation are weaker in previous epoch. The correlation
of SDI and wind stress curl supports this mechanism. The persistence of warming in the
recent epoch is evident from the strong correlation of barrier layer and SDI. The impact of
the subsurface variability is seen in the SST anomalies. During pre-76 positive SST anomalies
are present in the southern TIO and it persists up to April of the following year. But in recent
time period SST warming can be seen almost over the entire TIO which persists up to next
July. The subsurface mode influences the summer precipitation also. The correlation of
summer monsoon precipitation with SDI is strong over the Western Ghats and southern
peninsular India in post-76 period whereas in pre-76 period the correlation is comparatively
weaker. The composite of precipitable water also supports this pattern. So the meridional
subsurface mode has a strong impact on SST variability and summer precipitation which is
getting stronger in the recent years.
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VALIDATION OF GEKCO AND OSCAR PRODUCTS FOR THE INDIAN OCEAN
REGION USING IN – SITU OBSERVATIONS FROM MOORINGS
A Phanindra Reddy*, Simi Mathew, G. Latha and R. Venkatesan
National Institute of Ocean Technology, Chennai; [email protected]
Ocean surface currents obtained from downward looking Acoustic Doppler Current
Profiler (ADCP) attached to the moorings of National Institute of Ocean Technology (NIOT)
buoys has been inter compared with the two satellite derived surface currents; namely
Ocean Surface Current Analysis Real-time (OSCAR) and Geostrophic and Ekman Current
Observatory (GEKCO) at eight locations, four in Bay of Bengal (BoB) and four in Arabian sea
(AS). A period of 22 months buoy data is compared with satellite products for the Bay of
Bengal and around 10 months buoy data is compared with satellite products for Arabian
Sea. From the validation exercise carried out, it can be inferred that both the products
showed good agreement with the corresponding components of buoy observed surface
currents. The correlation coefficients for buoy and OSCAR are exceeding 0.7 and 0.6 for BoB
& AS respectively. The correlation coefficients for buoy and GEKCO were reasonable for BoB
with exceeding 0.6; while there is poorer correlation was observed for buoys in the AS with
GEKCO product. Even though OSCAR product is showing good correlation in open ocean but
coastal regions are less correlated with buoy data.
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22-24 March 2015
IMPACT OF CLIMATE MODES ON THE INTER-ANNUAL VARIABILITY OF ZONAL
CURRENTS IN THE EQUATORIAL INDIAN OCEAN.
Chinnu Sachidanandan* and P.M. Muraleedharan
The study aims at investigating the variability of zonal current in the equatorial Indian
Ocean in response to the climate mode signals like Indian Ocean Dipole (IOD) and Elnino
Southern Oscillation (ENSO). We have used Acoustic Doppler Current Profiler (ADCP) data
at three locations at the equator (77°E, 80°E, 90°E) from 2004 to 2007 collected under
Ocean Observing Program initiated jointly by Department of Science and Technology (DST)
and National Institute of Oceanography (NIO). The ADCP data at the eastern equatorial
Indian Ocean collected under the international program RAMA (Research moored Array for
African-Asia Australian Monsoon Analysis and Prediction) has also been extensively used in
this study. A model data for a longer duration to address the inter-annual time scale has
also been used. The data is generated using an Ocean General Circulation Model widely
known as NEMO (Nucleus for European modelling of ocean) forced from 1958 to 2007.
The validation performed on inter annual scales indicated that model currents are
significantly correlated with observations at both surface and subsurface depths. Empirical
Orthogonal Function (EOF) analysis performed on currents at the surface and the entire
water column showed zonal currents are more variable at upper layers than at depths. The
first leading mode of the EOF performed at depths significantly lead the second with 4
months, a clear indication that first mode often associated with the features of equatorial
jet and second one explains the under current. The simple correlation between principal
components (PCs) of first leading modes from EOF performed on surface and column data
produce significantly high values further emphasising the variability at the surface layer.
Linear regression performed between PC’s of surface currents and surface wind
vector/Sea Surface Temperature showed that the current responses are coupled with
IOD/ENSO climate modes. Partial regression analysis of leading modes of PC's with the
respective indices separates out the influence of IOD and ENSO thereby confirming that the
upper layer currents are strongly influenced by IOD rather than ENSO.
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SPATIO-TEMPORAL VARIATIONS IN SALINITY PROFILES OVER THE BAY OF
BENGAL
Kumar Ravi Prakash*, Vimlesh Pant
Indian Institute of Technology Delhi, New Delhi-110016; [email protected]
The surface circulation and freshwater flux, both local (evaporation or precipitation),
and from river runoff contribute in determining the thermohaline structure and its
variability in the Bay of Bengal (BoB). The northeast and southwest monsoons reverse the
direction of monsoon currents and coastal currents in the northern Indian Ocean. In this
study, we used salinity profiles from ARGO floats for the years 2005-2013 to study monthly,
seasonal, and annual variations in salinity profiles over over three sectors of BoB i.e.
northern (NBoB), central (CBoB), and southern (SBoB). These sectors have been selected
based on the climatological circulation pattern in the BoB, which plays important role in
governing salinity variability at seasonal and interannual time scales. Additionally, the
surface currents data from OSCAR and precipitation data from GPCP were used to analyses
observations. The effect of large river runoff into the northern sector of BoB is clearly seen
in the salinity profiles in NBoB with marked year-to-year and seasonal variability in top 100
m as compare to other two sectors. The CBoB shows reduced, but similar trend, in salinity
profile variability with a delay of about a month to that of NBoB. Interannual variability in
salinity profiles found to be maximum in NBoB, particularly in post-monsoon (ON) and
winter (DJF) seasons, where the differences in surface salinity between the years found to
be up to 2 psu. In the SBoB, the effects of summer and winter monsoon currents are clearly
visible in modulating seasonal variability in salinity profiles.
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22-24 March 2015
SUPPLEMENTING XBT OBSERVATIONS WITH SALINITY IN THE BAY OF BENGAL
Venugopal Reddy.T1, Ali.M.M2*, Gopala Krishna.V.V3
1
INCOIS,Hyderabad
NRSC,Hyderabad, [email protected]
3
CSIR-NIO,Dona Paula, Goa
2
Salinity and Temperature profiles together required for many of the oceanographic
studies. Compared to Conductivity,Temperature,Depth (CTD) observations which provide
both temperature and salinity, Expendable Bathy Thermograph (XBT) observations, giving
only temperature profiles are more. Hence, T-S diagrams have been used to estimate
salintiy from the temperature measurements. In this paper we present a neural network
approach to supliment XBT temperature with salinity data over Bay of Bengal (BoB). We
considered estimating salinity from temperature in the BoB as a challenging problem
beacause of strong salinity gradients, highly variable stability in both temporal and spatial
scales due to large fresh water flux.
For this purpose we used climatological (WOA-09) temperature and salinity profiles.
Present Neural Networks algorithm has one input layer with 5 neurons, one hidden layer
with 7 neurons and one output layer with one neuron. Since T-S relation have temporal,
spatial as well as depth dependencies we considered Time (month),Space
(latitude,longitude,depth), and Temperature as input to the model and salintiy as the
output.
This model has been used to estimate salinity using the above inputs from CTD
observations. Estimated salinity has been compared with actual CTD salintiy. The RMSE
varies from 0.643 at surface to 0.048 at 700 m.
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MARINE TECHNOLOGY &
MARINE ACOUSTICS
SESSION - 03
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MARINE TECHNOLOGY & MARINE ACOUSTICS
SESSION-03
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22-24 March 2015
GPS/GSM BASED SEAMLESS IN-SITU PROFILER FOR ATMOSPHERIC
BOUNDARY LAYER
Femy Paulose*1,2, Feby Paulose1, Gibies George2
1
Sree Narayana Gurukulam College of Engineering; [email protected]
2
The atmospheric boundary layer (ABL) is the energy source for the entire troposphere.
The solar radiation received at the earth surface is partially absorbed and partially reflected
by the surface depending on the nature of the surface. Absorbed energy is radiated as the
thermal (long wave) radiation, which is the primary energy source for the atmosphere. The
atmosphere also receives the sensible and latent heat from the surface. Temperature and
humidity profile of the atmospheric boundary layer provides the basic information’s on the
energy budget of the atmosphere especially in small scale.
Operational meteorological agencies used to take upper air sounding (Wang et al.
2001) twice a day (more frequently on special cases). But they have their own limitation in
monitoring minute details of the mesoscale (small scale) variability in the temporal and
spatial (horizontal and vertical) distribution of the ABL parameters. In this study we have
designed and implemented a new and simple instrument to build up the capability of local
bodies like panchayath, municipalities and corporations to directly monitor the local
weather conditions. Earlier Sankar and Norman (2009) attempted for such an instrument.
Recently, Femy et al. (2014) developed the minimal version of the instrument and
conducted the sensor calibration and temporal profiling of a single surface station. The new
instrument can be used in three different modes (a) Temporal profiling of single surface
station; (b) Horizontal profiling at the surface while mounted on an automobile; (c) Vertical
profiling using balloon. An improved version of the same with better GPS altitude resolution
can be used for a combined temporal cum vertical profiling while mounted with pulley and
rope on a tower observatory. This can also be used attached with an Unmanned Aerial
Vehicle (UAV) for three dimensional profiling of some specific systems like thunder storm.
Here we are presenting the basic system design and the preliminary analysis.
GPS-GSM based seamless in-situ profiler system consists of an observing platform and
a ground station. Observing platform is the balloon/automobile on which the embedded
systems along with the atmospheric sensors are mounted. A GSM module (SIM900) in the
instrument transmits the observed data along with the GPS information to the ground
station. Ground station is a laptop personal computer with a similar GSM modem (or a
mobile phone or a tablet system) to receive the data transmitted from the observing
platform. The atmospheric sensors BMP085 (pressure and temperature measurement) and
SY-HS-220 (humidity sensor) and GPS module (GTPA010) are driven by the microcontroller
(LPC2148, based on a 16-bit/32-bit ARM7TDMI-S CPU with real-time emulation).
The GPS module provides the information about the time, latitude, longitude and
altitude of observation platform to the microcontroller. Most computer programs that
provide real time position information understand and expect data to be in NMEA format.
This data includes the complete PVT (position, velocity, time) solution computed by the GPS
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receiver. The idea of NMEA is to send a line of data called a sentence that is totally self
contained and independent from other sentences. So to collect data on horizontal here
using GPGGA (Global Positioning System Fix Data) sentence code.
The whole data is transmitted to the ground station through the GSM transmitter in
the observation platform. The instrument has a temperature sensor with resolution 0.1
degC, pressure sensor with resolution 0.01 hPa and humidity sensor with resolution 1% RH
connected to the microcontroller. The range of humidity measurement is between 30% and
90% relative humidity. The range of pressure measurement is between 300 hPa and 1100
hPa. The valid range of temperature measurement is between negative 40 degC and
positive 85 degC Accuracy of pressure sensor is 0.01 hPa and that of humidity sensor is
about +_5%RH. The time required for BMP085 module to calculate temperature and
pressure are 4.5 ms and 7.5 ms respectively.
References:
Femy Paulose, Aby Mathew, Gibies George (2014) “GPS/GSM based embedded system for
atmospheric boundary layer profiling and weather monitoring” International Journal of
Science and Research (IJSR), Volume 3 Issue 9, September 2014.
Sankar.P, Suresh.R.Norman (2009) Embedded System for Monitoring Atmospheric Weather
Conditions Using Weather Balloon International Conference on “Control, Automation,
Communication and Energy Conservation”-2009
Wang J., Cole H.L., Carlson D.J., Paukkunen A (2001) Performance of Vaisala RS80
radiosonde on measuring upper tropospheric humidity after corrections, 11th Symposium in
Meteorological Observations and Instrumentation, American Meteorological Society, Jan.
2001.
115
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SESSION-03
OSICON-15
22-24 March 2015
ESTABLISHMENT OF SHIPBOARD AWS ON INDIAN RESEARCH VESSEL SINDHU
SADHANA
K. Vijay Kumar, Prakash Mehra, Yogesh Agarvadekar, Govind Ranade, G.P Naik, Ryan Luis,
Bharat Harmalkar, Devika V. Ghatge, Narayan Satelkar, and Pramath Keny
CSIR- National institute of Oceanography, Goa - 403 004; [email protected]
A seaworthy measuring system suitable for mounting aboard ship has been developed
and deployed at onboard Research Vessel Sindhu Sadhana (RV Sindhu Sadhna). The system,
Shipboard AWS (SAWS), contains tower-mounted meteorological sensors for surface
meteorological parameters, radiation sensors for radiative flux, sea surface temperature
(SST) for thermodynamics property of surface sea water, echo sounders for ocean depth
information, inertial navigational system and GPS for wind correction, ship attitudes and
geographical position respectively. SAWS is a state-of-the-art fully in-house designed and
developed system has capability to relay the information on local area network (LAN), which
has been tested over RV Sindhu Sadhana LAN configuration and data were viewed from
various nodes over the ship (for example, chief scientist cabin, data acquisition lab and
physics lab). The system is useful for surface meteorological observation, marine boundary
layer dynamics and air-sea interaction studies in conjunction with fast esponse high
frequency sensors for air-sea flux observations. It is also useful for coupled air-sea model
calibration and validation.
Fig.1 Installation of SAWS at onboard RV Sindhu Sadhana
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SPATIAL DISTRIBUTION OF SOFAR CHANNEL PARAMETERS OVER BAY OF
BENGAL
K.Ashalatha1, T.V.R.Murty2, K.V.S.R.Prasad3
1
Department of Meteorology & Oceanography, Andhra University, Visakhapatnam; [email protected]
2
CSIR- NIO, Regional centre, Visakhapatnam; [email protected]
3
Department of Meteorology & Oceanography, Andhra University, Visakhapatnam; [email protected]
The Present work reports the analysis of the derived SOFAR channel parameters (such
as channel depth, axial sound velocity, Conjugate depth, Sonic Layer depth (SLD), and Mixed
Layer Depth (MLD) in the Bay of Bengal. Sound is the prime source of energy to explore into
the ocean interior. It can use for long range underwater communication, detection of
underwater targets, etc. and also to determine the depth of the Ocean. To understand the
sound velocity distribution and it’s characteristics in the Bay of Bengal (0.5° – 23.5°N; 78.5° –
100.5°E), Levitus 2009 annual data is used. The SOFAR channel (Sound Fixing and Ranging
channel) is a horizontal layer of water in the ocean at which depth of sound speed is
minimum. The depth of Minimum sound speed within a sound channel called channel
depth. The depth of sound channel axis varies between 1100-1750 m in the Bay of Bengal.
In general, the depth of the channel axis Increases towards the northern latitudes in the
Arabian Sea, while it decreases in the Bay of Bengal. The depth below the deep sound
channel axis where the sound speed equals the speed at the source depth called conjugate
depth. Conjugate depth varying between 180 m – 420 m in the Bay of Bengal. Sonic layer
depth is the depth of maximum near-surface sound speed above the deep sound channel.
The range of sonic layer depth is varying between 10m – 40m. The quasi homogenous
region of the upper ocean, where physical properties like density, salinity and temperature
are nearly constant with depth called mixed layer depth .It shows the variation from 4m11m. The Bay of Bengal has depth limited nature of the profile. Then, the effective sound
channel lies much below the sea surface. As, a result, In underwater acoustics, that region in
the water column where the sound speed first decreases to a minimum value with depth
and then increases in value, due to pressure. Above the depth of minimum value, sound
rays are bent downward; below the depth of minimum value, rays are bent upward,
resulting in the rays being trapped in this channel and permitting their detection at great
ranges from the sound source
References:
RamanaMurty, T.V., Prasanna Kumar, S., Somayajulu, Y.K., Sastry, J.S., De Figueiredo, R.J.P.,
“Canonical sound speed profile for the central Bay of Bengal”, J. Earth. Sys. Science, 253263, 1989.
Munk, W.H., and Forbes, A.M.G., “Global Ocean Warming: An acoustic measure?” J. Phys.
Oceanogr. 19, 1765-1778, 1989.
Chen, C.T., and Millero, F.J., “Speed of sound in sea water at higher pressure”; J. Acoust. Soc.
America, 60, 129-135, 1977.
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22-24 March 2015
DEVELOPMENT OF MICROBIAL FUEL CELL BASED ENERGY HARVESTING
SYSTEM USING MARINE SEDIMENT FOR UNDERWATER APPLICATIONS
P. Janani*, S. Sakthivel Murugan, N. Archana
1
ECE Department, SSN College of Engineering, OMR, Chennai -603110; [email protected]
Underwater acoustic communication in shallow/deep water is a fast developing area
of research. Various systems used for underwater applications such as disaster warning
tsunami buoy systems, underwater sensor networks, underwater seismic observing
systems, Autonomous Underwater Vehicle, manned submersible vehicles, acoustic signal
processing submersibles used for defense purposes etc requires major power for operation.
In general batteries are used to power the systems. In this paper an energy harvesting
system for low power devices are proposed. This harvesting system uses marine sediments
(available in shallow/deep water) Microbial Fuel Cell (MFC) as a source for power
generation.
The system consists of marine sediment MFC and a power management system. The
voltage developed by the MFC is less than 0.7V. So, a power management system is used
between the MFC and the load to power the electronic devices in ocean water. The power
management system consists of Charge Pump Circuit, Super capacitor and Interleaved Boost
Converter. The charge pump circuit generates an output voltage of 1.4 V twice that of the
input voltage of MFC which is then stored in a super capacitor. The voltage stored in a super
capacitor is transferred to the Interleaved Boost Converter which boosts the voltage of 1.4V
to 6.8V which is the requirement of the load. Thus the design of a new underwater energy
harvesting system provides relentless and justifiable power supply for remote underwater
sensing, surveillance devices including data collections. Simulation results of energy
harvesting system are carried out using MATLAB.
References:
Guoxian Huang, 2013, A Biomass-based Marine Sediment Energy Harvesting System, Low
Power Electronics and Design(ISLPED), 359-364.
Meehan.A, 2011, Energy Harvesting with Microbial Fuel Cell and power management
system, IEEE Transactions on Power Electronics, 26, 331-355.
118
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RAIN FALL ANALYSIS USING NOISE MEASUREMENTS IN SHALLOW WATERS
OFF ANDHRA COAST
M. Ashokan*, G. Latha2, K. Nithyanandam3
Ambient noise measurements have been made in shallow water of Indian east coast
by deploying a moored buoy having a 21 element vertical hydrophone array of frequency
band 100 Hz to 20 kHz. The ambient noise data has been acquired and stored periodically in
a Real Time Operating System (RTOS) based data acquiring system. The sampling frequency
was kept at 50 kHz and sampling duration was 30 seconds. The noise data sets were
collected in once in every 3 hrs. The measurement periodicity of the data acquisition has
been monitored by an indigenously developed power controller board. The noise data sets
collected by the hydrophone element nearer to sea surface was taken for analysis. Along
with this moored buoy, another moored buoy has been deployed very near, for measuring
the surface weather parameters such as wind speed, wind direction, outside air
temperature and rain fall events. The rain fall events have been measured by using RM
Young make precipitation type rain gauge. The watch circle between these buoys was
around 500 m. The depth of the location is 25 m, whereas the hydrophone array was kept at
mid water column. Noise data sets and surface weather parameters have been collected
from 28 October 2014 to 17 December 2014. Within this period, totally 353 noise data sets
have been collected and 30 have been fallen in the rain fall events. The preliminary analysis
of measurements showed that predominantly the noise field is due to rain during rain
events, regardless of the wind [Ashokan et al., 2015]. This paper presents the work carried
out on the estimation of noise level pertaining to different rain fall rates such as light rain
(drizzling) and heavy rain in shallow waters off the North West Bay of Bengal. This research
has applications in finding different types of rain fall rates from the acquired ambient noise
data sets [Ma Barry B et al., 2005].
References:
Ashokan M., Latha G., and Ramesh R. (2015), Analysis of shallow water ambient noise due to
rain and derivation of rain parameters, Applied Acoustics, 88, 114-122.
Ma Barry B, Nystuen Jeffrey A, Lien Ren-Chieh. (2005), Prediction of underwater sound
levels from rain and wind, J. Acoust. Soc. Am., 117, 3555-3565.
119
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22-24 March 2015
CONVERTED WAVE AVO ANALYSIS FOR RESERVOIR CHARACTERISATION
Prabhakar Nayak, A. K. Rai
Indian Institute of Technology Bhubaneswar, Odisha-751007
Rock formation are characterised by their physical properties like elastic parameters
(modulus of rigidity, bulk modulus, lame parameter), mineral composition, porosity, fluid
content, etc. These properties are reflected in their seismic attributes as well. Change in one
of these parameters affects the ratio of compressional wave velocity (Vp) to Shear wave
velocity (Vs) of a formation. Poisson’s ratio, which is a function of Vp and Vs will vary with
physical properties of the rocks. Modern techniques of data acquisition and processing
provide tools using which converted S- wave information can be extracted. This PS- wave
analysis can provide us seismic attributes that can be analysed to obtain shear wave
reflectivity as well as density contrast information. The shear wave information from PSwave AVO modelling can be used along with PP- wave AVO analysis to find better models of
Poisson’s ratio variation. Poisson’s ratio variation and density contrast information from PSwave AVO analysis can be useful for better characterisation of reservoirs, and determining
saturation of fluid in the formations. Poisson’s ratio variations in formations may be better
attributes for reservoir characterization. Also the density considerably varies with the
porosity and fluid content. Therefore, Poisson’s ratio and density variation together may
provide better constraints than seismic wave speeds and other parameters.
References
Antonio, C. B., Ramos and Castagna, John P., 2001, Useful approximations for convertedwave AVO, Geophysics, 66, 1721–1734.
Xiucheng, W., Tiansheng, C., and Ji Yuxin, J., 2008, Converted wave AVO inversion for
average velocity ratio and shear wave reflection coefficient, Applied Geophysics, 5, 35-43.
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DEVELOPMENT OF DUAL MODE COMMUNICATION A NOVEL TECHNIQUE FOR
REAL TIME TSUNAMI BUOY SYSTEMS
R.Sundar, M.Arulmuthiah, S.Elango, D.Gowtham, R.Venkatesan, M.A.Atmanand
ESSO-National Institute of Ocean Technology, Pallikaranai, Chennai-100
Ocean Observation System erstwhile National Data Buoy Programme a group of
National Institute of Ocean Technology, Ministry of Earth Sciences was established in 1997
and is being maintain the Moored Buoy network in the Bay of Bengal and the Arabian Sea.
To detect and measure the tsunami events, NIOT has developed and installed the Tsunami
buoy systems in the Northern Indian Ocean Region from 2007 onwards which are
transmitting the real time water level data using INMARSAT communication. Currently
seven Tsunami buoy systems are working in the ocean and the data being shared to
National Data Buoy Corporation (NDBC), USA. Since the Tsunami event data is more critical
and these event datasets are transmitted through INMARSAT telemetry and normal tidal
variation datasets are transmitted through INSAT telemetry to reduce the cost and to
achieve self-reliance in technology for that a dual mode communication (INSAT &
INMARSAT) novel technique was implemented in Tsunami buoy systems. This paper
describes about the development, features and the successful implementation of dual mode
communication system for Tsunami buoy system for real time water level data transmission.
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AMBIENT NOISE VARIABILITY ALONG THE CENTRAL WEST COAST OF INDIA –
OFF GOA
R. Kannan*, G. Latha, G. Raguraman
National Institute of Ocean Technology, Pallikaranai, Chennai; [email protected]
Time series measurements of ambient noise were collected during the pre-monsoon
period March, April and May, 2013 off Goa in the shallow waters of Arabian Sea with an
interval of 3 hours between records. The buoy location is shown in Fig. 1. The twelve
element omni-directional hydrophone array is used for collecting ambient noise in the
frequency range 0.1 to 10 kHz. The wind speed measurements were also collected
simultaneously and it is used for verifying its influence on the ambient noise. Monthly
average wind speed is shown in Fig. 2. Since the fishing vessel activity in Goa is around 20 m
water depth [and the buoy location is also in the same region, it is decided to examine the
time series measurements of ambient noise at site off Goa with different source distribution
for long period variations (i.e., noise variations extending to periods of a month) in the
frequency band 0.1–5 kHz. The fishing information from the fisheries department of Goa is
used to validate the fishing vessel activity [Report of Directorate of Fisheries, 2010]. The
statistics of ambient noise datasets are reported in terms of regression analysis and
standard deviation. The spectrum was calculated using Welch’s method of averaging
modified periodograms windowed with a Hanning window, and fast Fourier transformed
with 50% overlap to provide multiple spectra which are averaged.
The results of empirical fitting [NL = Intercept + 20*slope*log (wind speed)] based on
analysis were used for noise level prediction and the model predictions [Ramji et.al., 2008]
compare well with the measured noise level and it is shown in Fig. 3. It is observed during
pre-monsoon period that higher the beaufort scale, higher the noise level. To study the
influence of wind on noise variability, the datasets are segregated according to wind speed
from 2 to 4 beaufort and the standard deviation is checked for frequencies upto 5 kHz
shown in Fig. 4. During pre-monsoon period, the predominant wind direction is from NW
and NE in which the wind comes from NW direction is stronger in magnitude which implies
that the sea breeze effect is more compared to land breeze effect from NE direction.
Further it was observed that the wind and vessel generated noise level measured in the premonsoon period falls approximately in the same range (62 to 73 dB). Since the buoy location
is near to a fishing range, local fishing vessel contributes to a large extent to the overall
ambient noise and hence the variability of ambient noise is high in the low frequency band
upto 2.5 kHz. The flat ambient noise variability at high frequency band shows the
predominance of wind noise which is uniform at the sea surface. Wind generated noise
source has a strong influence in the higher frequency band after 2.5 kHz. The average wind
speed during premonsoon period is 5.1 m/s. So the noise at this site is contributed by wind
as well as fishing vessel. The results are in good agreement with the literature [Sanjana et.
al., 2010]. Further it is planned to extend the analysis for different timings of the premonsoon period.
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FISH CHORUS RECORDED IN THE SOUTHEASTERN ARABIAN SEA: A
COMPARISON STUDY WITH OTHER SHALLOW WATER ENVIRONMENTS
M. M. Mahanty*, G. Latha and A.Thirunavukkarasu
National Institute of Ocean Technology, Pallikaranai, Chennai-100; [email protected]
Passive acoustic noise measurements were made in shallow water in the southeastern
Arabian Sea using an autonomous system, during month of January-May, 2011. Based on
the spectrogram analysis, two fish chorus are identified and primarly belonging to the family
Terapontidae and Planktivorous fishes. The recorded fish chorus are distinctive patterns in
daily timing, frequency content and call characterstics throughout the period. The
recordings are species-specific and can be compared with other shallow water
environments. The frequency content and call characterstics of two fish chorus are
comparable with the chorus recorded in shallow waters of Scott reef and Maret Island,
Australia which have been previously studied by McCauley (2012).The Terapontidae chorus
shown after dusk, maximal at the beginning of January to end of March, but ceased down by
month of May, whereas planktivorous fish peaked before midnight that displaying lunar
trend during 22ndJanuary-8thFebruary.The two chorus types differs significantly in their
acoustic characterstics, the planktivorous fish chorus are single broadband pulse from one
contraction of swimbladdar, where as Terapontidae chorus are a series of pulses of the
swimbladdar by anterior muscles contraction consecutively (McCauley, 2001). The
Terapontidae pulse repetition rate appeared in the frequency spectra at 0.1-0.12 kHz and
swimbladder resonant spectral peak is extended over 1-1.8 kHz. The planktivorous fish
chorus spectral maxima is observed near 0.6 kHz. The sharp dip at 0.9 kHz in the spectra of
the planktivorous chorus suggesting the fish were calling near the surface.The planktivorous
chorus are associated with feeding whereas,Terapontidae chorus related with spawning.
The spectral level during fish chorus is relatively 30 dB higher than the average ambient
noise spectra.
References:
McCauley, R.D. (2012), Fish choruses from the Kimberley, seasonal and lunar links as
determined by long-term sea-noise monitoring, Proceedings of Acoustics 2012 Fremantle,
Western Australia, November, 21-23.
McCauley, R.D. (2001), Biological sea noise in northern Australia: Patterns of fish calling.
PhD. Thesis, James Cook University Library.
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NOISE LEVEL VARIABILITY AND SPECTRAL CHARACTERISTICS OF SHALLOW
WATER AMBIENT NOISE AT VIZAG
K.K Noufal*, M.C Sanjana, G. Latha
National Institute of Ocean Technology, Pallikaranai, Chennai-600100, India; [email protected]
Shallow water ambient noise (AN) is well known for its level and frequency variability
because of different sources such as wind, rain, ship, biological organisms and
anthropogenic activities. AN measurements were carried out off Vizag at ~ 20 m water
depth during February-April 2014, in the range 0.025-20 kHz covering the entire sonic band
of frequencies, has been used for analysis. The data have been analyzed for wind induced
wave breaking, shipping and other prevailing noise sources.The measurement period spans
winter and summer months, seasonal variability in noise characterestics for this extreamly
shallow site is investigated. Further, the spectral content in noise due to tidal, hydro
dynamic factors etc also addressed. Time series, Average and Standard deviation of NL
were investigated for each month. Fluctuations of noise level during three months for
different frequencies, beaufort windscale and tide level were analyzed. Average noise
spectrum pattern were similar for all three months with slight level variation and Standard
deviation for NL, decreases with increasing frequency. Within the studied period and
frequency range NL shows significant variation below 5 kHz and modest change above 10
kHz.
References:
Gordon M Wenz (1962), Acoustic Ambient Noise in the Ocean: Spectra and Sources, The
Journal of The Acoustical Society of America. 34, 1936-1956.
Sanjana, M.C. (2010), Fluctuation and variability of shallow water ambient noise from time
series measurements, World Scientific Publishing Company 9(2), 193–202.
Mahanty, M.M. (2014), An investigation on the fluctuation and variability of ambient noise
in shallow waters of south west bay of Bengal, Indian Journal of Geo-Marine Sciences,43(5),
747-753.
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HINDUSTAN UNIVERSITY AUTONOMOUS UNDERWATER VEHICLE: DESIGN
AND IMPLEMENTATION OF THE POSEIDON AUV
S.Suryakumar*, Gokulavasan, Indrajeet Ghosh, A.Muthuvel, N.Prakash, K.Kamalakkannan
Hindustan University, Semmandalam, Cuddalore(dt), Tamil Nadu-607001; [email protected]
Abstract—POSIEDON is the first Hindustan University autonomous underwater vehicle
(AUV) designed and built by a team of 5 undergraduate students during the academic year
of 2014-2015. Completed the AUV in a six month design cycle, the vehicle was fully
modelled using Solidworks software is shown in Figure 1.2 and extensively simulated the
structural and flow analysis with ANSYS ,STARCCM+ software’s and manufactured almost
entirely in our campus. Grid Independent studies were carried out for the structural and
flow analysis. Various Turbulence models are selected based on the literature survey for the
flow analysis. Based on the Grid independent studies simulation is carried out for various
speeds for 0.1-0.5 m/sec. During generation of the meshes, attention is given for refining
the meshes near the AUV so that the boundary layer can be resolved properly. The typical
mesh for AUV and domain is shown in Fig 1.3 and a magnified view near the solid wall of
AUV is shown in Fig 1.4. The analysis is carried out for 0.25 million grid with 37 N force
acting on the thruster clamps. The FOS for materials is 3.2 and the yield strength is 172 Mpa
(the Maximum yield strength) of the material is 350Mpa hence the design is safe as shown
in Fig 1.1. From the Pressure contour diagram, the variation of the velocity of flow over the
AUV is seen at the velocity of 0.5 m/sec. At the bow of the AUV, stagnation condition is
clearly captured. Also, boundary layer formation is seen near the walls. As the flow
advances over the body, the velocity increases gradually and then reduces in the cap region
due to curvilinear nature of the cap geometry as shown in Figures from 1.5 and 1.6.
Poseidon presents a cheaper, stronger, lighter in weight of 22 kg and compact size of
0.7m*0.5m*0.5mas length, width and height of the vehicle and capable of working under 25
m depth. New advancements include full vehicle control of six degrees of freedom, a dualhull cantilevered electronics rack and hulls, overhauled wire routing for electrical systems,
and significant software for mission reliability and robustness. Poseidon sensor suite
comprises of inertial measurement units (IMUs), two vision cameras, and humidity sensors,
water sensors for kill switches, a depth sensor and an internal pressure sensor. Returning
features include a vacuum-assisted sealing system; hot-swappable battery pods, unified
serial communications, and flexible mission software architecture are installed. In
unstructured mesh, polyhedral mesh was chosen as it gives more accuracy for lesser
number of cells, thus the computational time is reduced. Testing of AUV is under progress.
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Figure 1.1 Factor of Safety for
AUV
Figure 1.4 Unstructured
mesh - magnified view near
the wall mesh
Figure 1.2 Isometric
view of the AUV
Figure 1.5 Pressure contour
on the starboard side
126
Figure 1.3 Section views
of AUV and Domain with
unstructured mesh
Figure1.6 Pressure contour
on the bow side mesh
OSICON-15
22-24 March 2015
MAPPING SLOPE MORPHOLOGY OFF GOA, WESTERN CONTINENTAL
MARGINS OF INDIA
Andrew Menezes*, S. M. Karisiddaiah, Bishwajit Chakraborty, K. Haris, William Fernandes
The slope morphology of the submarine gullies, ridges and the adjacent slump zone
off Goa, along the western continental margin of India were mapped utilizing multi-beam
bathymetric and single-channel seismic data (Chakraborty et al., 2014). Spatial data analysis
employing ArcGIS could uncover the fluid flow migration signature in the form of pockmark
seepages, traces of mud volcanoes and enhanced reflectors in the area. The analysis of the
thirty-three depth profiles from the gully, ridge and slump areas revealed down-slope
progression in gully incision and varying gradients in the gullies (1.19–4.07°) and ridges
(2.13–3.70°), whereas the gradients of the profile in the slump zone were comparatively
steady (2.25–2.51°). The scatter plot of the three slope characteristics, viz., gradient, mean
depth and root mean square (rms) relief, characterizes the profiles of the gullies, ridges and
the slump zone into three distinct clusters. The Principal Component Analysis (PCA) adopted
for validation also revealed similar categorization wherein the gullies and slumps showed
prominent clustering. The rms relief and gradient of the slump region display a positive
relation. The rms relief is a measure of the large-scale roughness, exhibiting increasing
roughness with declining slope gradient. Likewise increasing depth also contributes to
increasing roughness. However, relationship between the mean depth and the slope
gradient is negligible in the slump zone. Analysis using PCA to examine data variability
suggests that rms relief, gradients and mean depths are the influencing factors that control
the profile characteristics in the ridge, gully and the slump region respectively. It was
observed that the first two principal components (PC1 and PC2) together explain 94.33 % of
the total variance in the data.
Reference:
[1] Chakraborty, B., Karisiddaiah, S.M., Menezes, A.A.A., Haris, K.., Gokul, G.S., Fernandes,
W.A., and Kavitha, G. “Characterizing slope morphology using multifractal technique: A
study from the western continental margin of India,” Natural Hazards: 73(2); 2014; 547-565.
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A METHOD FOR IMPROVING MULTIBEAM BATHYMETRY DATA QUALITY
AFFECTED BY ERRONEOUS SOUND SPEED
William A. Fernandes*, Bishwajit Chakraborty
CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India; *[email protected]
The multi-beam echo-sounder systems operable at mid to high frequencies (12–400
kHz) are commonly employed to map the seafloor. The bathymetry and co-registered
backscatter data acquired using the echo sounding system can facilitate remote acoustic
seafloor studies. During data acquisition, we usually measure concurrent sound velocity
profile data from the survey area as well as continuous probing of the sound speed at the
face of the transducer array. The depths corresponds to each beam are assessed by the
echo sounding system employing ray bending and ray -tracing methods based on the sound
velocity of the profiled data [Beaudoin and Clarke, 2004]. The continuously probed sound
velocity data at the face of the transducer array is used for beam-forming. Based on the
computed reception angle the beam-steering has been achieved by applying suitable time
delay.
In the tropical environment the sound velocity pattern varies periodically. During the
survey, the spatial and temporal variations in sound velocity of the study area cause
artifacts in the acquired bathymetry and co-registered backscatter data. The analysis carried
out during the post-processing indicates that such artifacts are due to fluctuations in
measured sound velocity profile. These artifacts influences the slant ranged beams and
results distortion in the swath shape. Here, we have endeavoured to rectify refraction error
that causes the smiling or frowning distortion in the swaths. As mentioned above the
refraction error occurs due to incorrect sound speed at the face of transducer array or
sound velocity profile measured in the water column [Fanlin Yang et. al, 2007].
In this work, a technique has been developed during the data post processing stages
by applying correction coefficients computed from the acquired data and effectively applied
to enhance the data quality that results improved bathymetry map [Fernandes, 2011]. The
developed algorithm extracts the required parameters such as: beam Incidence angles, Time
Varied Gain (TVG) cross-over angles, raw depths, raw ranges, surface sound speed, sound
velocity profiles and related position data with total number of beams from the datagram
stored in the raw data. The shape of the swaths has been examined for the refraction
artifacts. The data are processed and the computed offsets are subsequently applied to
correct the refraction errors. At the end, the developed algorithm generates improved
bathymetry data and exported as ASCII format. The resulting output can be imported to
additional softwares including ArcGIS (to creating spatial maps) and Matlab (for advanced
statistical analysis). Additionally, the processed data has been converted to the binary
formats compatible to commonly used sonar data processing softwares. The proposed
technique can improve the bathymetry data quality affected by erroneous sound speed and
the resulting bathymetry map can be utilized for seafloor studies.
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References:
Beaudoin, J. and Hughes Clarke, J.E., “Retracing (and re-raytracing) Amundsen's Journey
through the Northwest Passage”, Proceedings of the Canadian Hydrographic Conference
2004, Ottawa,2004.
Fanlin Yang et. al, “A Post Processing Method for the Removal of Refraction Artifacts in
Multibeam Bathymery Data”, J Mar. Geo 30; pp. 235-247, 2007.
Fernandes, W. A., “A Method to Eliminate Refraction Artifacts in EM1002 Multibeam
Echosounder System”, NIO Technical Report, NIO/TR-01/2011.
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RECENT ADVANCES IN THE DESIGN OF SONAR HUMAN MACHINE INTERFACE
*Anjaly C Gopi, G K Nagarajan, Sumi A Samad and V S Shenoi
Naval Physical & Oceanographic Laboratory, Thrikkakara PO, Kochi – 682 021; [email protected]
In an era of technology where systems are controlled by software, User Interface (UI) is
one of the major factors that decide the usability of a system. UI otherwise known as Human
Machine Interface (HMI) is the most essential part of a distributed real time system
involving operator intervention. SOund Navigation And Ranging (Sonar) is one such
electromechanical system where human interaction is made possible only through HMIs.
Now a days various approaches are available to enhance HMIs which enable a single
operator to control the entire system.
In this paper an attempt has been made to showcase some of specialized techniques
that are used in enhancing sonar HMIs.(1).Integration of surveillance camera for
audio/video streaming to view/control the activities taking place away from Sonar Control
Room in the ship. (2)Picture In Picture (PIP) facility to preview the offline secondary page to
have an overview of the entire Sonar pages to take tactical decisions. (3)2D Visualization of
Towed array dynamics to visualize the dynamics of towed array when deployed underwater.
(4) Integration of computational intensive systems like Sonar Performance Modeling System
(SPMS) to Sonar HMI using Virtual Network Computing (VNC), which enables the operator to
control such systems through operator console. (5) Real time theme selection to change the
look and feel of HMI online to adapt to different environments in the platform.
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REFINEMENT OF SHALLOW WATER DEPTH ESTIMATION ALGORITHM USING
WEIGHTED LINEAR REGRESSION APROACH
Vinayaraj Poliyapram1, Venkatesh Raghavan1, Glejin Johnson2 and V.V. Sanil Kumar2
1
Graduate School for Creative Cities, Osaka City University, Osaka, Japan, [email protected]
2
Information concerning water depth of near shore water region is one of the most
basic requirements for coastal zone management. Bathymetry is especially important for
near coastal lines, where changes can occur rapidly due to sedimentation and erosion. Here,
an approach has been demonstrated to refine the shallow water depth estimation algorithm
using multi-spectral Landsat-8 data. The Visible+NIR bands (0.43 – 0.88 µm) from Landsat8
image were used to estimate bottom classes and depth. The common practice of previous
studies has been to calibrate a single global bathymetric inversion model for an entire image
scene. The performance of conventional global models is limited when the bottom type and
water quality vary spatially within the scene. To address the inadequacy of the conventional
global models, this paper presents a geographically adaptive weighted regression model to
better estimate depth.
Atmospheric and water column correction of five bands (0.43
– 0.88 µm) are carried out by Short Wave Infrared band (1.57-1.65 µm) using following
equation [Vinayaraj et al., 2014]
( )
(
((
))
)
(1)
Heterogeneous bottom type and water quality often lead to spatial non-stationarity of
the mathematical relationship between the remotely sensed pixel radiance and depth. The
corrected bands is used to estimate depth from geographically varying coefficients derived
Geographical Weighted Regression (GWR) between multi- spectral bands and in-situ depth
LiDAR for test site in Puerto Rico. The following equation explains the depth estimation
using multi-spectral bands by GWR [Su et al., 2013]
(
)
(
)
(2)
) geographical coordinates of point i and
Where,
is the estimated depth, (
(
) is the calculated value of the continuous function
(
) in point from depth
estimation carried out by multiple regressions from a global coefficient. The result derived
from the GWR is compared with the conventional global multiple regression. The accuracy
of the results has been evaluated with LiDAR data. GWR (R2 = 0.96, RMSE = 1.4 meter) and
global multiple regression (R2 = 0.75, RMSE = 1.5 meter). This study concluded that GWR
model is a better method in order to estimate depth from shallow water.
References:
Haibin Su, Hongxing Liu, Lei Wang,Anthony M.Filippi, William D. Heyman and Richard A.Beck
(2013), Geographically adaptive inversion model for improving bathymetry retrieval from
satellite multispectral imagery, IEEE transactions on Geosciences and Remote Sensing, 52(1),
465-476.
Vinayaraj, P., Venkatesh Raghavan, Shinji Masumoto, Glejin Johnson and Masita Dwi
Mandini Manessa, (2014), Investigation of algorithm to estimate shallow water bathymetry
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from Landsat-8 images, International symposium on Geinformatics for Spatial-Infrastructure
in Earth and Allied Sciences GIS-IDEA 2014, Vietnam.
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A VLSI BASED INTEGRATED DATA ACQUISITION SYSTEM FOR POLAR
OBSERVATORY
Lydia Kiruba R1*, M.Arul Muthiah2, R. Venkatesan2, A. Sivagami1
1
Asan Memorial College of Engineering and Technology, Chennai; [email protected]
2
National Institute of Ocean Technology, Chennai
This paper presents the development of a novel technique for subsurface multi sensor
mooring for Polar waters. Earth System Science Organisation (ESSO), National Institute of
Ocean Technology (NIOT) under the Ministry of Earth Sciences, is involved in the installation
of instrumented moorings for Polar waters to understand the Polar Region processes and
their influence on the Indian monsoon system. As real time data telemetry is not possible
due to the ice cover in surface, submerged self recording instrumented moorings are being
installed as a part of the study. The Polar observatory has threats of malfunction due to the
floating ice bergs and continuous ice cover in the Polar Regions. Hence there is a chance
that the system may get detached resulting in the loss of data and equipment.
As the collected data is more valuable, this design is being adapted to add adequate
data redundancy and to ease downloading facility. The objective is to design a hybrid system
using Inductive telemetry, VLSI and Acoustic technology. A reliable, low power and low cost
FPGA based Integrated Data Acquisition system is developed for the Polar Observatory. The
system is designed by programming the modules using VHDL in Xilinx, ISE design Suite 14.3.
The whole system is programmed and tested using the FPGA Spartan 3E kit and its
competence is observed.
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COLLECTION OF OCEANOGRAPHIC DATA IN MACRO TIDAL REGIME- GULF OF
KHAMBHAT EXPERIENCE.
M.Sankar, K.M.Sivakholundu, B.K.Jena, Vijaya Ravichandran, V.Suseentharan, Karunakar
Kintada
Oceanographic data like wave, tide and current were observed in Gulf of Khambhat
(GoK) over a year period during 2012-2013. Being a macro tidal regime, GoK poses a
challenging environment for any sustained observation campaign. This paper describes the
difficulties faced to install the observation systems and sustain them for more than one
year. A detailed account on planning, equipment selection, installation and retrieval
schemes have been presented. The split observatory system for tide, expendable platform
for tide and current were some of the improvisation made to overcome site difficulties.
High currents accompanied with scouring seabed warranted a customized observatory
scheme to overcome sinkage issues. The standard installation structures supplied by
Original Equipments Manufacturer meant for open sea were found to be inadequate for
collection of data in the GoK conditions. In order to overcome the difficulties prefabricated
steel tower with raft foundation, improvised life boats for current observations, expendable
frames for tide gauge installations were designed found to be cost effective and suitable for
local conditions. The iterative processes of starting from system configuration to the
customized system solution are explained after successful observations. Cost comparison
between the split tower configuration and conventional observatory tower works out to be
1:4 ratio with no compromise on the final data quality.
The design and methodology used to measure Wave, Tide and current will be
presented in this paper. As a result, now the GOK has been observed for tide, current and
wave at more than 20 locations over a year period which perhaps is the first time
occurrence in this part of the country in terms of the spatial coverage and duration.
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DEVELOPMENT OF DRIFTER BUOY FOR MEASURING CURRENTS IN SURF ZONE
V Suseentharan1*, K M Sivakholundu2, Basanta Kumar Jena3, M Ravinder4, R Balaji5
National Institute of Ocean Technology, Chennai; *[email protected]
This paper proposes a cost effective method of measuring surface currents in surf
zone using two technologies such as General Packet Radio Service (GPRS) and Global
positioning System (GPS). ARM based a low power module was developed with built-in high
accuracy GPS receiver and GSM modem powered from 14.5V, 56aH battery pack and
integrated in 30cm diameter buoy. An application has been developed to track GPS location
and send it with GPS time stamp to central server. The module is having flexibility to change
the configuration through SMS like sampling rate, data transfer interval, GPRS settings and
target server settings such as FTP, IP server details, sub-folder and so on. Modules are
available in different communication modes such as GPRS, Wi-Fi and INSAT based telemetry
system. The system has been implemented with more than one telemetry systems with
depending on site conditions. To minimize the wind driven movement of the buoy, a 2m or
5m drogue would be used based on the depth profile. A simple program has been written to
calculate surface velocity and direction based on Lagrangian method. The data set is
expected to be useful to oil spill model validation, HF Radar data validation and so on. The
paper discusses the basic architecture of module, options that can be made and the
experience gained during validation with LEO measurements
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HIGH STRENGTH TERMINATION TECHNIQUE FOR VECTRAN FIBRE ARMOURED
UNDERWATER TOW CABLES
Kiran Govind V*, Anshath Hussain, Thulasidas K R, Sabu Sebastian M
Naval Physical & Oceanographic Laboratory, Thrikkakkara (P.O), Kochi-21, Kerala; [email protected]
A typical towed sensor array system wet-end consists of electro optic-mechanical
cables, towed body and towed sensor array modules followed by a tail rope at the aft-end.
An active cum passive towed sensor array system uses negatively buoyant Heavy Cable (HC)
of length varying from 100 to 500 m, a neutrally buoyant Light Cable (LC) of length 100 m to
600 m, array modules of length 20 m to 30 m and a tail rope of length 10 m to 30 m.
The electro optic-mechanical (EOM) tow cables provide the optical, electrical and
mechanical connection of the towed body and array with electronic processors on-board
the ship. The tow cables transmit power to the underwater equipment and carry signals for
underwater surveillance. The steel armored Heavy Cable is negatively buoyant and plays an
important role in depth keeping of towed body and the array. The fibre armoured Light
Cable is nearly neutrally buoyant cable which ensures sufficient trail or standoff distance of
the linear array from the ship to keep the array away from self-noise of the platform and
also helps the array modules to be in the same depth as towed body.
The EOM tow cables used in towed array sensor systems have to meet contrasting
design requirements. In addition to having multiple numbers of electrical and optical lines,
the cables should have high tensile strength, optimum weight/ meter, radial hydrostatic
sealing at large hydrostatic pressure, minimum elongation, ease of operation & stowage, all
within a minimum overall diameter. The cables should also be capable of withstanding the
harsh marine environment and hydrodynamic forces experienced due to waves and currents
during operation.
The tow cables derive their mechanical strength from high strength armour materials.
The mechanical termination of the armour is a critical technique by which the loads on the
armour are transferred to mechanical structural member on either ends of the tow cable
without affecting the electrical or optical conductors inside. The final breaking strength of
the cable is determined by the efficiency of cable termination. An ideal cable termination
restrains the cable core and external strength members in such a manner as to duplicate the
stress distribution in the cable elements which would be present in an undisturbed
continuation of the original cable.
The mechanical strength for Light Cable to withstand high towing loads is provided by
the high strength fibre armour which lies just below the outer sheath. One of the high
strength fibre armour material most suited for underwater tow cables is Vectran, which is a
high performance thermoplastic multifilament yarn spun from liquid crystal polymer (LPC).
It has exceptional strength, superior fatigue and abrasion resistance, excellent creep
characteristics and moisture resistance.
In the present study, the evolution of a high strength termination technique for
mechanical termination of Vectran fibre armoured Light Cable is discussed. The technique
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employs a resin filled socket termination mechanism in which an epoxy based resin along
with a hardener is used for termination. Tensile tests were conducted on multiple
terminated cable samples using various epoxy-hardener combinations for achieving
maximum termination efficiency. Based on the study, a suitable epoxy-hardener
combination could be finalized which can provide the Light Cable a terminated tensile
strength of more than 150kN. The termination technique has been widely applied for
terminating Light Cables in various towed array systems and has successfully proved its
functionality during exhaustive sea-trials.
References:
Bash, F. J and Berian G. A (2001), Handbook of Oceanographic Winch, Wire and Cable
Technology.
Nowatzki, J. A. (1971), Strength Member Design for Underwater Cables, Underwater Cable
and Connector Committee, MTSE.
Bowers.W. (1973), High Strength-to-Weight Cable for Deep Ocean Projects, Proceedings of
the 22nd International Wire & Cable Symposium, 279 -285
Triantafyllou. M. S (1991), "Dynamics of cables, towing cables, and mooring systems", Shock
and Vibration Dig., vol. 23, pp.3 -8
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INTER-COMPARISON OF COLLOCATED CUP TYPE AND SONIC ANEMOMETER
ON THE MOORED COASTAL BUOY
Jagadeesh Kadiyam, G. Vengatesan, M Arul Muthiah, J. Vimala and Dr. R Venkatesan
National Institute of Ocean Technology (NIOT), Chennai; [email protected]
National Institute of Ocean Technology (NIOT) under the Ministry of Earth Science
(MoES), Govt. of India, started deployment of moored buoys in the Bay of Bengal and
Arabian Sea in 1997 to provide continuous time series measurements of surface
meteorological and oceanographic parameters at selected locations. These observations
help to improve the understanding of ocean dynamics from seasonal, intraseasonal, annual
and interannual time scales [1].
All the buoys are deployed with meteorological sensors like wind sensors, pressure
sensors, temperature and humidity sensors etc., out of which wind speed measurement is
important to study the cyclonic storms which are associated with low atmospheric pressure
and strong winds which induce divergent circulation in the upper ocean [2]. The aim of the
paper is to intercompare two types of anemometers viz. cup (Lambrecht, Germany) and
sonic (GILL Instruments, USA), which were collocated on a moored buoy. Currently, NIOT
deploys cup type anemometers in all the locations and this inter-comparison is done at one
of the Coastal buoys deployed in Bay of Bengal off Krishnapatnam, Andhra Pradesh at 14°
16’ 55’’N/80° 11’ 58” E for a period of 1 year. Later the retrieved sonic anemometer is
calibrated along with new sonic anemometer and Cup type anemometer in a Wind tunnel at
FCRI, Palghat. The comparison results of both the co-located field anemometers are done to
assess the performance of different types of anemometers in the marine environment.
References
R. Venkatesan, V. R. Shamji, G. Latha, Simi Mathew, R. R. Rao, Arul Muthiah and M. A.
Atmanand, (2013), New in-situ ocean subsurface time series measurements from OMNI
buoy network in the Bay of Bengal, Current Science, 104, 9.
R. Venkatesan, Simi Mathew, J. Vimala, G. Latha, M. Arul Muthiah, S. Ramasundaram, R.
Sundar, R. Lavanya and M. A. Atmanand (2014) Signatures of very severe cyclonic storm
Phailin in met–ocean parameters observed by moored buoy network in the Bay of Bengal,
Current Science, 107, 4
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A REVIEW ON THE INDIRECT ESTIMATION OF GEO-ACOUSTIC PROPERTIES OF
SEABED
V.K. Unny*, C.P. Uthaman, Nitheesh Thomas
Naval Physical and Oceanographic Laboratory, DRDO, Thrikkakara PO, Kochi-682021; [email protected]
Acoustic propagation in shallow water is viewed as a wave-guide phenomenon, with
the sea surface and seabed forming the boundaries. The acoustic properties of the seabed
to a depth of several wavelengths can have a strong effect on propagation. The modelling of
propagation requires estimates of such parameters as sound speed, density, attenuation,
and layer thicknesses etc which are collectively called the geo-acoustic properties of the
seabed. The direct measurement of these quantities is difficult and time consuming.
Therefore, methods have to be devised to infer these values from geo acoustic experimental
data. The swath multibeam echo sounders, digital side scan sonars and sub-bottom profilers
are the modern geo-acoustic instruments used for the sea bottom mapping. These
instruments can provide high resolution and high precision images of sea bed and are
capable to differentiate the roughness or softness of the bottom from the back scattering
strength of the acoustic signals. There are methods developed to determine the geo
acoustic parameters indirectly from the acoustic reflection and back scattering strength of
sea bottom. These are estimated from the vertical reflection profile data. This study reviews
the comparison of methods and results obtained with sample data collected.
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COOPERATIVE MOTION CONTROL OF MULTIPLE AUVS – CHALLENGES IN
IMPLEMENTATION
Manish Singh*, Nupur Thakker, Pramod Maurya, Gajanan Navelkar, Antonio Mascarenhas
National Institute of Oceanography, Dona Paula, Goa 403004; [email protected]
The past decade has seen the rapid development of AUVs in many countries. The
AUVs are now built from well proven technology products that are commercially available.
In order to achieve high performance and time efficient ocean exploration, the researchers
in marine robotics have shown an increased interest in cooperative motion control of
multiple AUVs. The challenges in cooperation include design of robust control algorithms to
execute missions of increasing complexity in the presence of communication losses without
direct supervision of human operators.
The literature on cooperative control algorithm is extensive and the types of algorithm
available vary in accuracy, complexity and theoretical robustness [1], [2], [3]. Despite these
advances, the literature published to address the issues of implementation is scarce. It is
crucial to emphasize that a proper implementation is at the core of a number of methods
used for multiple vehicle cooperative control to guarantee their practical robustness.
This paper addresses the issues and challenges of implementation of cooperative
motion control algorithms. As a contribution towards the development of robust
implementation, Robot Operating System (ROS) will be used to show its efficacy for
cooperation among two AUVs, one developed at NIO, Goa and other being developed at
CMERI, Durgapur. ROS is a cross language platform working in a distributed environment. It
can be used to establish a network among multiple vehicles for distributed intelligence as
well as to control each vehicle’s motion.
Finally, a distributed simulation environment was established and a series of hardware
in loop simulation were carried out to demonstrate the efficacy of implementation in ROS.
References
Reza Ghabcheloo, António Aguiar, António Pascoal, Carlos Silvestre, I. Kaminer, J. Hespanha,
(2009) Coordinated path-following in the presence of communication losses and time
delays. SIAM - Journal on Control and Optimization, 48, 1, 234-265
António Aguiar, João Almeida, Mohammadreza Bayat, Bruno Cardeira, Rita Cunha, Andreas
Häusler, Pramod Maurya, André Oliveira, António Pascoal, A. Pereira, Manuel Rufino, Luís
Sebastião, Carlos Silvestre, Francesco Vanni, (2009). A Cooperative Autonomous Marine
Vehicle Motion Control in the scope of the EU GREX Project: Theory and Practice, Proc. of
OCEANS 2009 IEEE Bremen, Germany
Skjetne, R., Moi, S., and Fossen, T.I. (2002) Nonlinear formation control of marine vessel.
IEEE Conference on Decision and Control 2(10-13), 1699-1704
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VALIDATION OF INDIAN TSUNAMETER IN LABORATORY ENVIRONMENT
Tata Sudhakar* and G.A. Ramadass
Tsunameter is an instrument for the early detection of Tsunamis. Any violent
geological disturbance under the water, which can cause displacement of large amount of
water, can cause tsunami. Earthquakes, landslides, volcanic eruptions, explosions are some
of the known causes of tsunami. The resultant tsunami surface wave can cause widespread
damage to property.
After the 2004 Indian Ocean Tsunami, India has implemented Tsunami Early warning
system using inputs from Seismic, Deep ocean pressure recorders (DOPR), tide gauges and
HF radars. The data from DOPRs play very important role in confirming the existence of
Tsunami wave in the deep sea. India has developed DOPR with help of industries (Sonardyne
(UK), Envirtech (Italy) and Oceanor (Norway)). As the manufactures are developing the
systems for the first time, It is very important to validate the newly developed systems for
Tsunami response before Deployment at Sea as the Tsunami is a rare event. The authors
developed methods to validate the systems in laboratory environment. Simulation studies
based on the NOAA’s tsunami detection algorithm have been carried out and the program
developed has been successfully employed on the data obtained from Tsunameter in the
validation trails at NIOT. New test methods, hitherto not available, were designed and
Tsunameter consisting of pressure recorder, acoustic modem and buoy were tested under
simulated conditions. After successful validation of these DOPRs were deployed in Bay of
Bengal and Arabian Sea. The warning system was operational from September 2007 and
results obtained during detection of tsunami on 12 th September 2007 at 18.10 UTC were
discussed
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UNDERSTANDING EARTHQUAKES AND TSUNAMI HAZARD IN BAY OF BENGAL
Saroj K. Dash, A. K. Rai*
Indian Institute of Technology Bhubaneswar, Odisha – 751007, [email protected]
The Northern Bay of Bengal is located near several complex tectonic zones, such as
the Sumatra-subduction zone, the NE Himalayas and Eastern Ghats. Observations show that
earthquakes of magnitude 5 and above (Fig. 1) are common in the Northern Bay of Bengal.
A recent earthquake of magnitude 6 near the Puri coast suggests that neo-tectonic stress is
accumulating in the region. More than 10 km thick loose sediments are accumulated in the
Bay of Bengal over the geologic time-scale. Any moderate to large size earthquake may
induce submarine landslides in canyons located in Bay of Bengal. Strike-slip earthquake may
also disturb steep slopes and cause stability failure in loose sediments. Local tsunami
generated due to such submarine landslides can cause severe devastation along the coasts
of Ganga Bhramaputra delta where over 60 million people live within 10m of above sealevel.
Fig. 1. (a) Earthquakes in Bay of Bengal. Focal mechanisms are taken from CMT earthquake
catalog, and plotted if available. (b) Number of earthquakes vs. magnitude plot, indicating
that magnitude 5 and above earthquakes are dominant in Bay of Bengal.
Moderate size local tsunami may be generated by these earthquakes and submarine
landslides at the sides of deep canyons with thick sedimentation. Studying relation between
spatial distribution of earthquakes, their source parameter, and submarine canyons can
provide useful information about tsunami hazard in Bay of Bengal.
References
Cummins, Phil R., 2007. The potential for giant tsunamigenic earthquakes in the northern
Bay of Bengal. Nature, Vol. 449, no. 6, 75-78
Matthew J. Hornbach et. al., 2010. High tsunami frequency as a result of combined strikeslip faulting and coastal landslides, Nature Geoscience, Vol. 3, 783–788
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ROLE OF MARINE TRANSGRESSION IN THE FORMATION OF KACHCHH
BAUXITE, GUJARAT, INDIA
P.S.Choudhury1, G.N.Jadhav1 and D.U.Vyas2
1
Dept. of Earth Sciences, Indian Institute of Technology Bombay, Powai, Mumbai; [email protected]
2
Gujarat Mineral Development Corporation, Gujarat, India
India is home to most high grade bauxite deposits that occur along the coastal belts
with a maximum lateral extension of 30-60Km located in the Kachchh region, Gujarat, India.
These bauxite deposits formed over the flood basalts of Deccan Volcanic Province and
oriented from NE to SW direction. The bauxite belt was a result of subsidence, sea level
fluctuations, ground water circulation, marine transgression and marine regression during
early Eocene (~ 56Ma) period.The pure bauxite which is whitish to light/ bluff coloured is
generally poor in iron content and occur near to the shore while the impure bauxite which is
more iron rich gradually occur in landward direction. The segregation of Al-rich horizon,
alucrete zone and the Fe-rich horizon, ferricrete zone which is due to the highly mobile
nature of iron radicals than the aluminium under optimum Eh- pH condition. A welldeveloped vertically zoned profile of bauxite occur in Kachchh region, Gujarat, India; where
the top layers of bauxite zone is followed by lithomargic clay containing kaolinite overlying a
clearly visible and altered basaltic parent rock. In many saprolitic bauxite there is
preservation of well-developed relict basaltic textures.
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EVALUATION OF NUMERICAL MODELS FOR
PALAEOTSUNAMI/PALAEOSTORM DEPOSITS FROM SAURASHTRA COAST,
WESTERN INDIA
Drasti Gandhi1, 2*, S.P.Prizomwala1, N.Y.Bhatt2, Kapil Mohan1, B.K. Rastogi1
1
Institute of Seismological Research, Raisan, Gandhinagar 382009, India; *[email protected]
2
The Geology Department, M. G. Science Institute, Navrangpura, Ahmedabad 380009, India
Since last two decades, studies pertaining to detachment, transport and emplacement
of coastal boulders have received wide attention among scientists. A detailed study of the
deposited boulder features – size, shape and rock density and their initial position prior to
the transport – is extremely important when reconstructing the possible morphodynamic
scenarios (Pignatelli et al. 2009). Nott (1997, 2003) derived equations for boulder responses
to Palaeo - storms and tsunamis waves. But the application of Nott’s equation and its
accuracy has been debated by several workers in different scenarios. Nott’s (2003) equation
assumed that boulder before being detached had only one side exposed to wave and is
limited by five sides while Pignatelli et al. (2009) considered only three faces and the under
surface of the boulder in Joint bounded block Scenario.
Several scattered and imbricated ridge of boulders are found along the Southern coast
of Saurashtra above high tide level and as inland as 30m. Possible wave heights and wave
responsible for dislodging boulders from offshore and transporting them inland have been
calculated for Diu Coast using both the equations by Prizomwala et al. (2015). The results
concluded that a tsunami wave of 3.5 m height transported all the boulders to their present
position. However the same numerical model applied to the boulders of SW Saurashtra
coast suggested their possible deposition by a storm wave. Similarly comparison of historical
storm data with tsunami models suggest conflicting remarks, hinting at a need to reevaluate these numerical models in light of local geomorphic and geological setting.
References:
Nott, J (1997), Extremely high-energy wave deposits inside the Great Barrier Reef, Australia:
determining the cause—tsunami or tropical cyclone. Mar Geol 141, 193–207.
Nott, J (2003), Waves, coastal boulder deposits and the importance of pre-transport setting.
Earth Planet Sci Lett 210, 269–276.
Pignatelli, C., Sanso P., and Mastronuzzi G. (2009), Evaluation of tsunami flooding using
geomorphologic evidence. Mar Geol 260(1–4), 6–18.
:10.1016/j.margeo.2009.01.002.
Prizomwala, S. P., Drasti Gandhi, Vishal M. Ukey, Nilesh Bhatt and B. K. Rastogi (2015),
Coastal boulders as evidences of high energy marine events from Diu Island, west coast of
India: storm or palaeotsunami? Natural Hazards. DOI 10.1007/s11069-014-1371-5.
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DEMARCATION OF NEAR SUBBOTTOM SEDIMENT STRATA OF SHALLOW
WATERS USING IMAGE PROCESSING
Satyanarayana Yegireddi
Center for High Energy Systems and Science, DRDO, Hyderabad-500069; [email protected]
Demarcation of shallow water sediment strata and sedimentation pattern provides
vital information on depositional environment and prevailing dynamics of any area. Such
information is useful in offshore geo-engineering activities, planning and dredging of
navigation channels, and neotectonics investigations. Sediment coring throws light on the
sediment structure to a limited depth, is expensive and time consuming. Conventional
geophysical investigations like shallow water seismic reflection studies can hardly delineate
thin layers due to poor resolution. Sub-bottom profilers operating at a relatively high
frequency are being used to resolve thin sediment layers. But at times, the quality of
images from sub-bottom profilers is very poor and difficult to distinguish any thin sediment
layers due to high ambient acoustic noise interference. Low acoustic impedance contrast
among recent sediments and change in the direction of depositional pattern also cause
masking of the features and difficulty in discrimination of the sediment layers.
Therefore, degradation in acoustic image quality due to strong ambient noise and
depositional environment variability, poses a major challenge in delineation/ identification
of thin upper sediment layers from conventional geophysical signal processing. Present
studies address the above mentioned problem using image processing and successfully
demonstrates with application to noisy sub-bottom acoustic images.
Image processing techniques known for their applications in medical imaging, pattern
recognition and remote sensing applications, are being used in identification,
tracking/search and classification problems effectively. Image processing exploit the
statistical measures are efficient in even detecting weak boundaries of the features, as they
utilise the spatial variations. Image segmentation techniques using pixel based and
continuity based method are widely used both qualitative and quantitative analysis of image
feature. Continuity based method utilises threshold level adjustment (Al-amri et al, 2010)
and Gaussian low pass filter applied with the test images under study appears to be
promising. Intensity histogram is the prime importance in segmentation process and fixing
the thresholding strategies.
The methodology was applied to two subbottom images of subbottom profiler with
operational frequency of 6-12 kHz, acquired from two different offshore locations with
water depth ranges from 60-65m (Satyanarayana and Thomas, 2014). Both the images
show strong reflections associated with the seabottom, as the acoustic impedance contrast
was quite strong between water and seafloor sediments. However, weak layer interfaces
corresponding to first image and distorted, discontinuous interfaces associated with second
image show no improvement in clear demarcation of the boundary of subsurface layers
through conventional geophysical signal processes sing. Interestingly, image segmentation
able to clearly demarcate the weak acoustic reflectors and further infers the splitting of
upper sediment layer in the second image into two layers, associated with very weak
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reflectors. The sediment structure suggests the variation in local depositional environment
and instability of the area. Such information has significance in offshore construction and
other dredging operations. Classification from textural analysis using grey level cooccurrence matrix (GLCM), a method using higher statistical moments suggests that the
inferred layers features vectors derived from GLCM, exhibits the more similarities of the
upper layer.
Therefore, some image processing tools like segmentation and textural analysis
methods can effectively be exploited to supplement the other geophysical methods, in
shallow water applications.
References :
Al-amri S, Kalyankar NV, Khamitkar SD (2010), Image segmentation by using threshold
techniques, J Comput. 2(5):83-86.
Satyanarayana Yegireddi and Nitheesh Thomas (2014), Segmentation and classification of
shallow subbottom acoustic data using image processing and neural networks, Mar.
Geophys. Res. 35, 2, 149-156
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DISTRIBUTION OF REE IN SEDIMENT CORES FROM THE THANE CREEK,
MUMBAI
Lina L. Fernandes *, Pratima M. Kessarkar, V. Purnachandra Rao
CSIR-National Institute of Oceanography Dona Paula, Goa -403 004; [email protected]
Sediments from two cores from the Thane creek, Mumbai, one near the creek head
and another near creek mouth, were analyzed for their grain size, mineralogy and REE
chemistry to better understand the down-core distribution of REE and controls on REE. The
sediments were largely clayey silts or silty clays. Smectite -dominated sediments were the
most dominant in both cores. The REE content ranged from 112-127 µg/g near the creek
head and 117-136 g/g near creek mouth and were lower than in Post-Archean average
Australian Shale (PAAS). The PAAS-normalized REE patterns showed MREE- and HREEenrichment with positive Pr, Eu and Y anomalies. The results further showed low REE values
at middle portions of both cores. The Y values also increased at the middle portions of the
core near the creek head and decreased in the core near the creek mouth. REE distribution
is controlled largely by source rock composition in both cores. Eu anomaly was largely due
to plagioclase feldspar. It appeared that the core at creek mouth showed the signatures of
early diagenesis which were masked by the primary REE depositional conditions, whereas
the core near the creek head exhibited the influence of both source rock composition and
early diagenesis.
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GEOCHEMISTRY OF THE SURFACE SEDIMENTS WITHIN AND BELOW OXYGEN
MINIMUM ZONE FROM THE SOUTHWESTERN CONTINENTAL MARGIN OF
INDIA
Pratima M. Kessarkar*, G. Parthiban, J.N. Pattan, Lina L. Fernandes, Supriya G. Karapurkar,
Siby Kurian, V. Purnachandra Rao
CSIR-National Institute of Oceanography Dona Paula, Goa -403 004; [email protected]
Surface sediments within and below the oxygen minimum zone (OMZ) across the
transect of the continental slope off Goa, Mangalore and Kochi were investigated for grain
size, clay mineralogy, environmental magnetic properties, total organic carbon (TOC), total
nitrogen (TN), CaCO3, 15N, 13C, major, trace and rare earth elements (REE). The dissolved
oxygen in near bottom waters was low off Goa (0.03-2.30 ml/l) and increased towards
south, i.e., off Mangalore (0.11-2.50 ml/l) and Kochi (0.23-2.64 ml/l). Median grain size of
the sediments ranged between 6.3 and 41.7 µm, with relatively finer grain size along Goa
transect. Smectite and kaolinite were dominant minerals followed by illite and chlorite in
sediments of all transects. Smectite showed increasing trend offshore with increasing depth.
Magnetic susceptibility (lf) values ranged between 13 and 42 ×10-8m3kg-1, with relatively
high values off Goa and Mangalore compared to Kochi. The CaCO3 content ranged from 20
to 67 %, with relatively higher values off Goa, whereas TOC (0.9-8.6%) and TN (0.90-0.98 %)
contents showed decreasing trend in sediments below ~ 1200 m depth in all the profiles.
The 15N ranged from 3.6 to 7.2 ‰, with higher values off Goa. The total-REE (∑REE) content
was lower in Goa than in Mangalore and Kochi. The terrignous elements (Sc, Rb Sr, Th) were
lower in sediments off Goa than in Mangalore and Kochi transects. The concentrations of
redox sensitive elements (Mn, Cr, V, Mo) were lower in sediments associated with OMZ and
their concentrations increased with increasing depth in oxygenated sediments below OMZ.
The results suggest that the sediments at relatively shallow depth were hinterland –
derived, whereas those at deeper depths may be Deccan trap-derived. It appears that the
sediments off Goa received low concentrations of terrigenous elements than those off
Mangalore and Kochi. Organic matter is largely marine in all the three transects. Higher 15N
values in sediments off Goa compared to Mangalore and Kochi suggest higher water column
denitrification rates with probable contribution from the perennial denitrification zone.
Lower concentrations of redox sensitive elements in sediments with low oxygenated waters
and higher values with more oxygenated waters indicate oxidation of sediments during
early diagenesis.
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DELIVERY OF PARTICULATE ORGANIC CARBON DURING THE GREAT FLOOD OF
KRISHNA RIVER IN OCTOBER 2009
C. Prakash Babu*, V. Ramaswamy, P.S. Rao
The Krishna River experienced unprecedented floods during October 2009. High
rainfall combined with water release from dams in the upper reaches triggered intense
floods downstream. The nature of fluvial organic matter transferred to the coastal region
was studied by analyzing suspended particulate matter (SPM) from the Krishna estuarine
region for C:N ratios and δ13Corg collected during the flood from a bridge downstream
Vijayawada. The SPM showed high C:N ratios (14-19) and heavy δ13Corg values (-21 to -23‰)
during the initial flood period which drastically changed to low C:N ratios (7-9) and light
δ13Corg values (-26 to -27‰) during the later part of the flood. We show that the particulate
organic matter during the initial period of the flood is derived from the semi-arid region of
India as coherence is noticed between SPM and riverbed sediments. In contrast, the
receding waters during the later period of the flood carried mainly C3 type organic matter
organic matter from the deltaic region.
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MINERALOGY AND RARE EARTH ELEMENTS IN SEDIMENT CORES FROM THE
MANDOVI ESTUARY, WESTERN INDIA: INFERENCES ON SOURCES OF THE
SEDIMENTS
Prajith, A., Rao, V. P.* and Pratima M. Kessarkar
CSIR- National Institute of Oceanography, Dona Paula, Goa-403 004; [email protected]
Mineralogy and rare earth elements (REE) of bulk sediments in the gravity cores
collected along transect of the Mandovi estuary, western India were analyzed to determine
the sources and controls on REE distribution. The collected four sediment cores from the
Mandovi estuary represent four environmentally significant sites (upper, middle, lower
estuary and Aguada Bay). The length of recovered cores varied between 79 cm and 47 cm,
and was longer in cores from upper/middle estuary than in lower estuary/bay. Quartz was
the predominant mineral in sediments of all cores. The upper and middle estuary sediments
showed higher proportion of iron ore minerals than in lower estuary / Aguada Bay. The
sandy sediments from the middle estuary and bay showed high proportions of feldspars.
REE of sediments varied from 37 to 160 g/g in different cores and were lower than in
Post-Archean Australian Shale (PAAS; 185 g/g). The total Y of sediments varied from 8.5 to
37.1 g/g. REE showed strong positive correlation with both clay and silt fractions
(correlation ranges from 0.53 to 0.9) and were higher in clayey silts than in sand/sandy silts.
The light to heavy REE ratios (LREE/HREE) of sediments (range from 15.8 to 18.7) were lower
than in PAAS (24.7). The PAAS-normalized rare earths and yttrium (REY; Y inserted between
Dy and Ho) patterns of sediments showed middle REE (MREE)- and HREE-enrichment with
positive Eu anomaly (Eu/Eu*) and variable Ce anomaly (Ce/Ce*). The upper estuary showed
positive Ce/Ce* and this value decreased towards bay sediments. The gradual decrease of
Ce/Ce* with increasing organic carbon (OC) towards core top of the upper estuary and
inverse correlation between OC and Ce anomaly indicated reduction of Ce in early
diagenetic conditions. High positive Eu/Eu* values were associated with high sand content
in the sediments. Positive Ce and Eu anomalies are inherited from ore material. High Y/Ho
ratios in clayey silts are due to redistribution of Y and Ho by adsorption onto organic-rich,
clays. Variations in Sm/Nd ratios are similar to that of Eu/Eu* in cores from the lower
estuary/bay and are controlled by mineral constituents of the sediments. The REY of
sediments is primarily controlled by its texture and REE of source sediment, which is ore
material-dominated in the upper/middle estuary and silicate material-dominated in the
lower estuary/bay.
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STABLE ISOTOPIC INVESTIGATION OF PORITES CORAL FROM MINICOY ISLAND
A. A. Fousiya1, S. Chakraborty2*, H. Achyuthan1, Naveen Gandhi2, Nitesh Sinha2, Amey Datye2
1
Department of Geology, Anna University, Chennai, *corresponding author; [email protected]
2
Indian Institute of tropical meteorology, Pune
Corals are the most important component of the marine ecosystem found in vast
areas of the tropical oceans. Reef building corals are one of the best known archives that
provide high quality records of ocean atmospheric variabilities on sub seasonal resolution
spanning up to a few hundred years. The isotopic and chemical tracers incorporated in coral
skeleton are known to provide useful information, such as, sea surface temperature,
salinity, upwelling intensity, oceanic circulation etc. Lakshadweep Islands and Maldives in
the north Indian Ocean harbor various types of corals and several workers have studied
them for paleoclimatic/paleo environmental reconstruction. It has been demonstrated that
isotopic analysis of corals from these regions are useful proxies for SST (Chakraborty and
Ramesh, 1997) and monsoon rainfall over the Kerala coast (Sortz et al. 2010, 2011).
30.50
35.35
30.00
35.30
35.25
29.50
35.20
29.00
35.15
28.50
35.10
28.00
35.05
SSS (g/Kg)
SST (°C)
The Minicoy Island belonging to the Lakshadweep Archipelago also contains various
types of corals and some workers have studied their morphology and distribution (Pillai
1971; Jayabaskaran, 2009). But corals from the Minicoy Island did not receive much
attention for palaeoclimatic investigation. Minicoy Island is strategically located as far as
monsoon circulation is concerned (Gardiner, 1900). Additionally the oceanographic
characteristics of this region may offer some added advantage for coral analysis. For
example, the climatology of the monthly SST and salinity variations show that they are
almost out of phase (Figure 1). Since coral δ18O is inversely proportional to SST but directly
varies with SSS, the effects of these two parameters are expected to get added, resulting
enhanced coral isotopic signal.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Figure 1: Climatological (1989-2013) variations of sea surface temperature (red) and sea
surface salinity (blue) around the Minicoy Island (8.0N-9.0N, 72.5E-73.5E).
We have collected a Porites spp. from the Minicoy Lagoon (MSL: 13ft, 08°16’55 N,
73°03’17 E) at a water depth < 2m during low tide condition on Oct/21/2013. The x-ray
picture of this sample identifies annual banding spanning for 24 years (1989-2013). The
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mean annual extension rate over this period is ca. 7.7mm.yr-1. Stable carbon and oxygen
isotopic analysis of these bands reveal that the isotopic composition is controlled by kinetic
fractionation. The isotopic records have been examined in respect of various oceanatmospheric parameters to explore their potentials as a proxy for past climatic /
environmental conditions.
The SST anomaly (deviation relative to the long term monthly mean of 1989-2013)
was calculated for the months of Jul-Aug-Sep when sea surface cools due to monsoon
induced upwelling. High negative anomalies were observed in 1992, 1996 and 2013. Out of
these three years the coral δ18O showed increased values in 1992 and 2013, implying that
coral δ18O is sensitive to changes in sea surface temperature. The coral δ18O showed
somewhat weak but very significant correlation with the SST (r= -0.32, p< 0.002, n = 77).
The relationships between coral δ18O and Indian monsoon indices have also been examined.
It has been found that coral δ18O is weekly correlated (r=0.16) with the rainfall over the
Peninsular India as well as with the all India rainfall index (r=0.12).
Chakraborty et al. (2012) demonstrated that δ18O of corals are sensitive to the
thermodynamic index of Indian summer monsoon (TISM, defined in Xavier et al. 2007). We
have examined this relationship in case of Minicoy coral. TISM has been calculated for the
period of 1989-2013 as outlined in Xavier et al. (2007) and then correlated with the mean
annual values of coral δ18O (r=0.23). Though the connections between coral δ18Oand
monsoon indices are not strong, however they are similar to that observed in case of other
corals belonging to the Indian ocean (Chakraborty et al. 2012).
References:
Chakraborty, S. and Ramesh, R. (1997), Environmental significance of carbon and oxygen
isotope ratios of banded corals from Lakshadweep India, Quat. Int. 37(3), 55-65
Chakraborty et al. (2012), Pacific coral oxygen isotope and the tropospheric temperature
gradient over the Asian monsoon region: a tool to reconstruct past Indian summer monsoon
rainfall, J. Quat. Sci. (27) 269-278, DOI: 10.1002/jqs.1541
Storz, D. & Gischler, E. (2011), Coral extension rates in the NW Indian Ocean reconstruction
of 20th century SST variability and monsoon current strength, Geo-Mar Lett DOI:
10.1007/s00367-010-0221-z
Jeyabaskaran, R. (2009), New record of corals from Lakshadweep Islands, Rec. Zool. Suv.
India, 109 (part-1), 53-64.
Pillai, C.S.G. (1971), The distribution of shallow water stony corals at Minicoy Atoll in the
Indian Ocean with a checklist of species, Atoll, research Bulletin, No-(141), 1-12.
Xavier, P.K & Goswami B.N. (2007), An Analog Method for Real-Time Forecasting of Summer
Monsoon Subseasonal Variability, American Meteorological Society, DOI:
10.1175/2007MWR1854.1.(133), 749-764.
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ANTHROPOGENIC IMPRINTS ON A SEDIMENT CORE OFF GOA FROM THE
ARABIAN SEA – A ROCK MAGNETIC & GEOCHEMICAL APPROACH
Tyson Sebastian*, Sangeeta Naik, B.Nagender Nath, D.V.Borole
Rock magnetic and geochemical analyses combined with 210Pb dating were carried out
on a 1.03 m long gravity core collected off Goa from Arabian Sea at 15°30.07'N; 73°39.21'E
to investigate the mining induced sedimentation changes. A drastic increase in linear
sedimentation rate from 0.187 cm/year to 1.63 cm/year subdivides the core clearly into two
sections at a depth of 37 cm corresponding to an age of 1979 AD. The mineral magnetic
concentration parameters – low frequency magnetic susceptibility (LF), Susceptibility of
Anhysteric Remanent Magnetization (ARM), Saturated Isothermal Remanent Magnetization
(SIRM) - also experience a sharp increase at 37 cm suggesting a common origin. The core
location in this study is close to the mouth of Mandovi – Zuari River system, which flows
through the mining belt of Goa. The open cast iron ore mining in Goa and its transport
through road and waterways necessitates the removal of surface material overlying the ore
formations and thereby generates abundant debris most of which ultimately reach the
Arabian Sea either waterborne or windborne. The iron ore production in Goa has increased
from 1.09 Million tonnes (Mt) in 1953 to 30.73 Mt in 2007. The comparison between
magnetic susceptibility and the production of iron ore through mining from 1950 – 2000 AD
indicates that the increase in sedimentation rate and magnetic concentration parameters
are coeval and can be attributed to mining.
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WET DEPOSITION OF MIDDLE-EAST DUST OVER THE INDIAN PENINSULA
V. Ramaswamy*, Prakash Babu
During June to September when the southwest monsoon spreads humid maritime air
over the Indian Peninsula resulting in a substantial reduction in ambient surface- aerosol
concentrations, the northwesterly Shamal Winds lift dust from the MiddleEast and transport
it eastward over the Arabian Sea. In this study we show that the dry, warm and dusty
Shamal Wind override the low-level Findlater Jet of the SW monsoon and transport large
amounts of dust over Indian Peninsula at heights above 1.5 km. The total wet deposition of
dust wet deposited over Goa annually is ~20 g m-2. Mineralogy, chemistry and isotopec
studies show them to be derived from the Middle-East. The crustal dust neutralizes the
acidity and increases the pH of rainwater over Peninsular India. After the Shamal winds
subside in mid-August, the composition of rainwater reverts from alkaline to acidic range
due to soluble ions derived from local carbonaceous aerosols.
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PRELIMINARY OBSERVATIONS OF GEOMORPHOLOGICAL,
SEDIMENTOLOGICAL AND MINERALOGICAL CHARACTERISTICS OF THE
ARNALA BEACH AND ARNALAPADA ISLAND, THANE DISTRICT,
MAHARASHTRA, INDIA
S. D. Iyer, A. R. Gujar, D. K. Naik, S. S. Gaonkar, R. A. A. Luis, F. K. Badesab
Investigations are underway along the ~20 km long coastal belt of Arnala beach, Thane
District, Maharashtra. The area lies between the rivers Vaitrana in the north and Ulhas in
the south and also includes the Arnalapada Island that is located across the mouth of River
Vaitarna. Minor creeks intersect the beach before joining the Arabian Sea. More than three
decades ago the Directorate of Geology and Mines (Maharashtra) and the Geological Survey
of India reported the occurrences of heavy minerals and presence of mercury, respectively
from the above areas. Besides these there are no detailed reports of the Arnala beach and
Arnalapada Island. Our comprehensive studies include seasonal profiling (16 profiles, 5
seasons, 6 field works), geological and geomorphological observations and collection of
sand samples from the surface (57) and from (61) layers from 16 pits of 1  1  1 m
dimension. Analyses were carried out to characterise the sediment parametres and
mineralogy.
The foreshore is flat with a gentle gradient while in the backshore a temporary berm
and semi-consolidated karal rocks are present. The latter is composed of quartz and shell
and at places extends for at least 1 km as a raised beach. The area was divided into 4: north
Arnala near the Vaitarna mouth (Area A), central Arnala (Area B), south Arnala i.e., Vasai
beach near Ulhas River (Area C) and Arnalapada Island (Area D). The areas A, C and D are
highly disturbed due to human activities (fishing, jetty constructions, tourists etc). In Area B,
rock platform of altered fine grained basalts occurs in the intertidal zone and also offshore.
This ~2 km long platform is exposed during the low tide and probably represents the
shoreward extension to the offshore islands including Arnalapada. Fair season and pre-,
during-, and post-monsoon observations revealed severe erosion at some places and
accretion at others. For e.g., in Area B the raised beach at Bhuigaon and end of Rangaon
have been largely destructed while in Area C trees have been uprooted.
The surface sediments are fine grained, nearly uniform in size (mean 3Φ) and derived
from more than one source. Silt and clay increases between Areas B and C due the proximity
of the Ulhas River mouth and presence of extensive mudflat and mangroves. Significant
concentration of heavy minerals occurs in the surface sediments. Heavy minerals present in
the backshore and in the raised beach, are up to 93% and contain ilmenite (<1 to 37%) and
magnetite (<1 to 47%). The pit sediments are medium to very fine grained (mean 2.62Φ).
Significant concentration of heavy minerals occurs in surface sediments and are up to 65%
with ilmenite (<2 to 27%) and magnetite (<1 to 35%).
Based on seasonal topographic data and sedimentology, quantification of sediment
erosion and accretion and changes in coastal configuration and heavy minerals are
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evaluated. Furthermore, magnetic susceptibility studies and their relevance to palaeosediment deposition would also be investigated.
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PARTITIONING OF METALS IN DIFFERENT BINDING PHASES OF MARINE
SEDIMENTS: IMPORTANCE OF METAL CHEMISTRY
P. Chakraborty
CSIR-National Institute of Oceanography, Dona Paula, Goa, [email protected]
Distribution of metals in different binding phases of marine sediments provides
chemically significant description of metals-sediment interactions. This study describes the
influences of ligand field stabilization energy (LFSE), Jahn-Teller effect and water exchange
rate (k-w) on metal distribution in different binding phases of marine sediment. It was found
that Cu had highest affinity for organic binding phases in the studied sediments followed by
Ni and Pb. However, Pb had highest association with Fe/Mn-oxide phases followed by Ni
and Cu. Faster k-w of Cu (II) (1×109 s-1) increased the rate of complex formation of Cu2+ ion
with the ligand in the organic phases. The Cu-ligand (from organic phase) complexes gain
extra stability by the Jahn-Teller effect. The combined effects of these two phenomenons
increased the association of Cu in the organic phases of the sediments than Ni and Pb. The
smaller ionic radii of Ni2+ (0.72 Å) than Pb2+ (1.20 Å) increase the stability of Ni-ligand
complexes in the organic phase of the sediments. In addition to that high LFSE of Ni (II)
(compared to Pb2+ ions) make Ni-organic complexes increasingly stable than Pb. High k-w
(7×109 s-1) of Pb did not help it to associate with organic phases in the sediments. The high
concentration of Pb in the Fe/Mn-oxyhydroxide binding phase was probably due to coprecipitation of Pb2+ and Fe3+. High surface area or site availability for Pb2+ ion on Feoxyhydroxide phase and greater binding strength over simple precipitate surface was
probably responsible for the high concentration of Pb in Fe/Mn oxyhydroxide phase. The
decreasing concentrations of Cu in Fe/Mn–oxyhydroxide phases with the increasing Cu
loading in the sediment suggest that Cu did not prefer to associate with Fe/Mn
oxyhydroxide phases. Increasing concentrations of Cu in organic phases with the increasing
Cu-loading suggest that enough binding sites were available for Cu in the organic binding
phases of the sediments. This study also describes the influence of sedimentary organic
carbon (terrestrial and marine derived OC) in controlling these metals distribution and
speciation in marine sediment.
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ISOTOPIC FINGERPRINTING OF ATMOSPHERIC DUST OVER ARABIAN SEA
A. Kumar*, K. Suresh, P. P. Padalkar, C. Prakashbabu, V. Ramaswamy
CSIR- National Institute of Oceanography, Dona Paula, Goa-403004; [email protected]
The Arabian Sea (AS), one of the most biologically productive oceanic regions (Barber
et al., 2001) surrounded by the arid and semi-arid (Arabian and Omani deserts on the west
and Thar Desert in the north-east) area, receives a significant amount of aeolian dust
deposition (Shao et al., 2011) due to its proximity and favourable meteorological conditions.
In addition, a very recent study (Duchi et al., 2014) over southern Himalayas have indicated
the influence northern African dust during winter months, making the majority of tropical
dust belt area as an important contributor of dust to the AS. Apart from wind driven coastal
upwelling during summer monsoon (Barber et al., 2001) and convective mixing in winter
period (Madhupratap et al., 1996), dust deposition has been hypothesized to be an
important driver for phytoplankton productivity (Naqvi et al., 2010) in the AS from daily to
seasonal time scale. In order to assess the impact of dust deposition to the biogeochemistry
of the Arabian Sea, it is very important to identify the sources of transported dust. Several
proxies (e.g. elemental and mineralogical composition and their ratios) have been used to
track the transport and sources of dust. Naturally-occurring radiogenic isotope systems (e.g.
Sr, Nd, and Pb) are, however, one of the robust tracers for dust provenances and have been
efficiently used for tracing regional to inter-continental dust transport (Kumar et al., 2014).
For example, Kumar et al. (2014), have clearly shown a very similar Sr and Nd isotopic
signature in the aeolian dust samples collected from Mali (a sampling location in northern
Africa; mean 87Sr/86Sr = 0.713, ƐNd = -12.2) and in Tobago and US Virgin Islands (mean
87
Sr/86Sr = 0.711, εNd = -12.2 and mean 87Sr/86Sr = 0.710, εNd = -12.1, respectively) located
across the Atlantic Ocean and thus demonstrated the transatlantic dust transport using
radiogenic isotopes. In this study, the potential source areas of mineral dust contributing to
Arabian Sea, will be scrutinized based on satellite images and then geochemically
characterized by analyzing radiogenic isotopes (Pb, Sr, and Nd) in the surface soil/sediment
samples The sources located in the northern Africa have been characterized to infer dust
provenace in the coastal African region as well as in the Amazone basin (Abouchami et al.,
2013). A similar strategy will be applied to comprehensively characterize the sources located
in the Middle East and north-western part of India (Thar Desert) and will be used to
decouple dominant sources impacting towards the dust load over the AS on spatial as well
as temporal scales. In this presentation, some of the preliminary results related to the
source (Thar Desert) characterization will be discussed.
References:
Abouchami, W. et al., (2013), Geochemical and isotopic characterization of the Bodélé
Depression dust source and implications for transatlantic dust transport to the Amazon
Basin. Earth and Planetary Science Letters, 380, 112-123.
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Barber, R. T.,et al. (2001), Primary productivity and its regulation in the Arabian Sea during
1995, Deep Sea Res., Part II, 48, 1127–1172.
Duchi R., et al. (2014), Synoptic-scale dust transport events in the southern Himalaya,
Aeolian Res., 13, 51–57
Kumar, A., et al. (2014), A radiogenic isotope tracer study of transatlantic dust transport
from Africa to the Caribbean, Atmos. Environ., 82, 130–143.
Madhupratap, M., et al. (1996), Mechanism of the biological response to winter cooling in
the northeastern Arabian Sea, Nature, 384, 549–552.
Naqvi, S.W.A., et al. (2010), The Arabian Sea as a high-nutrient low-chlorophyll region during
the late Southwest Monsoon, Biogeosciences, 7, 2091–2100, doi:10.5194/bg-7-2091-2010.
Shao, Y., et al. (2011), Dust cycle: An emerging core theme in Earth system science, Aeolian
Research, doi:10.1016/j.aeolia.2011.02.001
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DISTRIBUTION AND SPECIATION OF PB IN COASTAL SEDIMENTS AROUND
INDIA
Sucharita Chakraborty*, Parthasarathi Chakraborty and B. Nagender Nath
CSIR-National Institute of Oceanography, Dona Paula, Goa, 403004; [email protected]
Distribution and speciation of Pb in the coastal sediments around India were
investigated in this study. An attempt was also made to identify the factors that control Pb
speciation and its bioavailability in the coastal sediments. The average total Pb
concentrations in the coastal sediments were found to be 21.6 ± 8.05 mg.kg-1 in the east
coast and 14.99 ± 6.04 mg.kg-1 in the west coast of India.
Geochemical fractionation study showed that Fe-Mn oxyhydroxides phase was the
major binding phase for Pb and controlled Pb-speciation in the oxic coastal sediments
around India. In average highest percentage of total Pb was found to be associated with FeMn oxyhydroxide phases in the sediments collected from the northern part of both the
coasts followed by the south west >central east and central west, and minimum amount of
Pb was found to associate with Fe-Mn oxyhydroxide phases of the sediments collected from
the south east coast of India. Organic carbon was the second major binding phase (among
the non-residual phases) of Pb in the coastal sediments. However, except central west
coast, binding sites of organic carbon were not available for Pb in the coastal sediments.
Labile complexes of Pb (a good indicator of bioavailability) (water exchangeable and
carbonate-bicarbonate complexes of Pb) was found to increase with the increasing total Pb
loading in the coastal sediments form central west coast of India. This study indicates
anthropogenic input of Pb in the coastal sediments in this area may increase bioavailability
of Pb in future.
The concentrations of Pb associated within the structure of the sediments (residual
phase) was found to carry source rock signature along the coast. The concentrations of Pb in
the residual phase of the sediments were found to show regional similarity in the northern
part of the east coast and the northern and central part of the west coast of India. This
finding suggests that similar source rocks probably contributed to the respective coastal
sediments. However, sediments collected from the central, south east and south west coast
of India showed variation in Pb concentration in the residual phase suggesting different
source rock contribution to the coastal sediments in these areas. This is the first study that
describes Pb distribution and its speciation in coastal sediments around India.
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HIGH RESOLURION HOLOCENE PALEOMAGNETIC SECULAR VARIATION
RECORDS FROM BAY OF BENGAL
A. Usapkar1, P. Dewangan1*, F.K. Badesab1, A. Mazumdar1, T. Ramprasad1, K.S. Krishna1, N.
Basavaiah2
1
CSIR-National Institute of Oceanography, Dona Paula, Goa; [email protected]
2
Indian Institute of Geomagnetism (IIG), Panvel, Navi Mumbai
Paleomagnetic studies are being carried out worldwide to establish high resolution
paleosecular variation records (PSV) that can be used to correlate regional stratigraphy and
to understand the geodynamo processes responsible for the generation of Earth’s magnetic
field. PSV records obtained from rapidly deposited, well-dated sedimentary sequences act
as a continuous and reliable recorder of Earth’s intensity and directional variations. Prior to
direct observations, the variation of Earth’s magnetic field can be reconstructed using the
PSV records which can help in understanding the temporal and spatial variations of Earth’s
magnetic field. During Holocene, most of the PSV records are documented from Europe,
North America, central Asia and South East Asia. However, such high resolution PSV records
are not available in the high sedimentation regions of Bay of Bengal. Therefore, we attempt
to establish the high resolution, continuous PSV records from Krishna-Godavari (KG) basin,
Bay of Bengal using two Calypso piston cores MD161/8 (~30m, water depth-1033m, 15°
51.8624'N, 81° 50.0692'E) and MD161/13 (~29m, water depth - 647m, 16°01.9684'N,
81°42.7909'E) acquired onboard M/V Marion Dufresne for gas hydrate studies. The PSV
records are evaluated for their potential to act as a reliable tool for magnetic stratigraphy as
well as to understand the geodynamo processes over Bay of Bengal.
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INITIATION OF OCEAN BOTTOM SEISMOMETER EXPERIMENT IN THE
ANDAMAN BACK ARC BASIN
K.A. Kamesh Raju*, Pawan Dewangan, Aswini, K.K., Yatheesh, V., Pabitra Singha, Kiranmayi S
The Indo-Burmese range and the Andaman arc system in the northeast Indian Ocean
define a zone of underthrusting of the Indian plate below the Southeast Asian plate, leading
to the formation of a major island arc trench system. The Andaman island arc including the
Andaman and Nicobar islands together with the Andaman back arc basin is a part of this
major arc trench system. The deep Andaman back arc basin is formed due to the initiation
of spreading activity within the central Andaman trough separating the Alcock and Sewell
seamounts. The complex tectonics of the region results from the oblique subduction, varied
rates of subducting Indian plate beneath the SE Asian plate along the zone of subduction
and the large variation in the age of the subducting plate along the length of the trench. The
region is seismically very active and witnessed the devastating M9.3 tsunami event of
December 2004 and its aftershocks. A passive Ocean Bottom Seismometer (OBS)
experiment was planned in the Andaman Sea to study the pattern of microseismic, local and
teleseismic earthquakes. The primary objectives of the OBS experiment are to define the
stress pattern and to understand the crustal structure of the Andaman back arc basin using
the velocity model estimated from the earthquake data. Twelve units of three component
broad band seismometers were deployed in the Andaman back arc basin during December
2013. The deployment locations were selected based on the tectonics and the seismicity.
These units were recovered in May 2014, resulting in a 4 month period of continuous
recording. The OBS receivers documented in greater detail an earthquake swarm that
occurred in the Off Nicobar region during March 2014 due to an M6.5 event. The analysis of
data is in progress to understand the seismological characteristics of the earthquake swarm
events, micro earthquakes, local events and the teleseismic events in order to gain insights
into the crustal structure of the region.
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SULFUR AND IRON SYSTEMATICS OF A CORE (MD161-15) FROM THE
KRISHNA-GODAVARI BASIN, BAY OF BENGAL
M. Carvalho, A. Mazumdar*
CSIR- National Institute of Oceanography, Dona Paula Goa – 403004
Corresponding author: [email protected]
Here, we present the concentration profile of pyrite sulfur (CRS - Chromium Reducible
Sulfur) and highly reactive iron (FeHR) in a core (MD161-15) off Krishna-Godavari Basin, Bay
of Bengal. The core was recovered on board R/V Marion Dufrense from a water depth of
983m at 16°00.5700'N; 82°03.4502'E. The available reactive iron (ferrihydrite:
FeOOH•0.4H2O+lepidocrocite:γ-FeO(OH)+goethite FeO(OH)+hematite: Fe2O3) in the
sediment (FeD) was extracted with buffered sodium dithionite solution following standard
method. The highly reactive iron (FeHR) is the sum of dithionite bound iron (FeD) and pyrite
bound iron (FeCRS). A total of 105 and 70 samples were analysed for CRS and FeD
concentrations respectively. CRS concentration profile in the present study essentially
represents pyritization trend through the sediment column. The CRS concentration in the
core varies from 0.0028 to 1.3 wt% and shows overall progressive increase in the
concentration from top to bottom of the core with several high & low concentration
peaks.The low CRS concentrations may be attributed to the reduced flux of reactive iron
bearing minerals and/or reduced production H2S required for sulfidization. Focused H2S
production at the paleo-sulfate methane transition zone could also lead to enhanced
pyritization. The FeHR concentration varies from 0.76 to 2.8 wt%. The FeHr concentration
decreases gradually from 1.7 to 0.76 wt% downcore to the depth of 1192 cmbsf and from
here it progressively increases upto 2.81wt% at 3077 cmbsf with several intermediate
concentration spikes.The TOC content ranges from 0.2 to 2.2 wt%. TIC content ranges from
a negligible amount to ~4 wt%. A sharp rise in the TIC content (high content of foraminifera)
is observed between 10 to 13 mbsf spanning the approximate time of the last glacial
maxima (LGM). The high TIC content (up to 3 wt%) between 27-30 mbsf is attributed to the
presence of authigenic carbonates (Joshi et al., 2014) formed via anaerobic oxidation of
methane pathway, as evident by the highly depleted 13C values (−41 to −52‰ VPDB).
Reference:
Joshi , R.K., Mazumdar A., Peketi , A. Ramamurty , P.B. Naik , B.G. Kocherla , M. Carvalho ,
M.A. Mahalakshmi , P., Dewangan P. and Ramana,M.V.,(2014), Gas hydrate destabilization
and methane release events in the Krishna – Godavari Basin, Bay of Bengal, Marine
Petroleum Geology, 58.
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INFLUENCE OF LAND USE PATTERN ON DISTRIBUTION OF ORGANIC MATTER
IN A TROPICAL LAGOON
Arindam Sarkar*, B.Nagender Nath
Elemental concentration, stable isotope of organic carbon (OC) and nitrogen (TN) in
bulk sediments and different size fractions were determined to investigate the nature and
burial patterns of sedimentary OC in a tropical lagoon from the southwest coast of India.
This study revealed that anthropogenic activity and land use pattern had a significant
control on the composition and distribution of organic matter (OM). The overall OC
concentration (0.25 to 4.49%, avg. 2.05±1.18%) was low compared to other eutrophic lakes
because of clastic dilution as large amount of sediments are being discharged here.
Southern part of the lake contained higher OC (avg. 2.21±1.20 %) compared to northern
part of the lake (avg. 1.80±1.18%) possibly due to better preservation of OM in the
sediments overlain by lower oxygenation conditions and deposition of significant amount of
soil organic matter (SOM) from agricultural fields, which had higher preservation efficiency.
The discrimination diagram of δ13Corg vs. N/C molar ratio (following the method of Keli et al.,
1994) for clay fraction confirms presence of significant proportion of SOM in the southern
region of the lake. The contribution from SOM decreased towards north corresponding to
the change in land use pattern in the adjacent watershed area of the lake. The watershed
area surrounding the southern part is extensively cultivated present day. Thus this region
seems to receive huge amount of SOM as surface run-off from these agricultural land.
However, the northern region is mostly urbanized and it was reflected by negligible
concentration of SOM in the sediments. A quantitative estimate using four end-member
analysis revealed that about 32% and 21% of the total OM were constituted by SOM in the
sediments collected from the southern and northern part of the lake respectively. It also
revealed that the marine contribution was higher in the northern area.
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NATURE OF SULFIDIZATION WITHIN A SEDIMENT COLUMN OFF MAHANADI
BASIN, BAY OF BENGAL, INDIA
Brahmanand Sawant1, A. Mazumdar1*, Maqbool Yousuf2, Aditya Peketi1
1
CSIR-National Institute of Oceanography, Goa 403004; [email protected]
2
Sector 2A, Al-Farooq Mosque; H.NO. 152 Srinagar - 190018
A sediment core (MD161-19) was recovered from the Mahanadi offshore basin for
pore fluid chemistry and Fe-S speciation. The ~39 m long core was recovered onboard
Marion Dufresne from a water depth of 1480m at 85°41.1669’E; 18°59.1020’N. Sulfate
concentrations were measured using Dionex-600 Ion chromatograph. Total alkalinity was
measured on board following gran titration using Metrohm Autotitrator (Titrino 799 GPT).
The sulfate concentration profile shows quasi-linear trend with a gradient of 1.61 mM/m.
The sulfate methane transition zone (SMTZ) lies within 1500-1900 cmbsf. The total alkalinity
increases steadily downcore and reaches a maximum of 22 mM at the SMTZ and
subsequently decreases gently. Chromium reducible sulfur (CRS-pyrite) was extracted from
the sediment using boiling 1 M CrCl2 (in 6N HCl) in an oxygen free reaction vessel with
continuous nitrogen flow. H2S trapped by reduction of sulfide is trapped as CdS in a
cadmium nitrate solution and subsequently re-precipitated as Ag2S by adding AgNO3. The
colloidal suspension of Ag2S was boiled for 10 minutes to produce consolidated Ag2S lumps
which are subsequently collected on 0.2 µm nitro cellulose filter paper and washed with
distilled water. The Ag2S lumps were oven dried and weighed for CRS content (Canfield et al
1986). A total of 250 samples were analysed for CRS concentration. The CRS concentration
varies from 0.002 to 0.64 wt% and shows multiple zones of high well defined high
concentration peaks. The degree of pyritization ranges from 0.3 to 56 %. High DOP suggests
significant sulfidization by hydrogen sulfide produced via organoclastic or AOM driven
sulfate reduction. The highly reactive iron concentration (FeHR) ranges from 0.34 to 3.17
wt%. A high resolution δ34CRS, δ13TIC measurement may help in detailed understanding of
the pyritization process in the sediment column.
References:
Canfield, D., R. Raiswell, J. Westrich, M. Christopher, C. M. Reaves, and R. A. Berner (1986),
The use of chromium reduction in the analysis of reduced inorganic sulphur in sediments
and shales, Chem. Geol., 54, 149–155, doi: 10.1016/0009-2541(86)90078-1.
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DEPOSITIONAL ENVIRONMENT OF THE SURFACE SEDIMENTS IN CENTRAL
INDIAN BASIN (CIB), INDIAN OCEAN BASED ON THEIR MAJOR ELEMENT
COMPOSITION
Simontini Sensarma1, Ranadip Banerjee1* and Subir Mukhopadhyay2
1
2
Department of Geological Sciences, Jadavpur University, Kolkata 700032
In order to establish the depositional environment of the surface sediments in the
Central Indian Basin (CIB) of the Indian Ocean, major element composition of surface
sediments at 65 locations were studied. The study area, bounded by 11°- 16°S latitude and
73°-79°E longitude, is comprised of calcareous (bordering the ridge areas and basinal highs,
mostly calcareous ooze), siliceous (covering the central part, comprised mostly of
radiolarian and diatomaceous oozes) and pelagic clay or red clay (covering the south eastern
and southern part, comprised mostly of Fe-oxide rich clay particles of both authigenic and
detrital origin) sediments.
Oxidative environment (Mn*) although present throughout the basin, but in variable
intensity, possibly indicate non uniform pattern of movement of oxygen rich Antarctic
bottom water (AABW) in the study area. Although the overall sedimentation pattern is
hydrogenetic in both calcareous and pelagic clay domains, in siliceous ooze region,
diagenetic influence seemed to be more dominant due to high biogenic silica input and less
oxidative environment (low Mn* value). Both iron (Fe) and manganese (Mn) content,
especially their non-terrigenous part, were lowest in siliceous sediment, compared to
calcareous and pelagic clay regions. Using shale normalized Ti content as an indicator of
terrigenous input (Terri%), it was observed that the Terri(%) is variable in all sediment types,
while the signature of Terri(%) is traceable till 15°30’S latitude. The variable distribution
pattern of Mnexcess and Feexcess indicate that in addition to continental source, there is
definite additional source of supply of both these elements through sediment diagenesis
and weathering of adjacent mid-oceanic ridge rocks. Presence of volcanic precursors almost
in all sediments also could be a source for Feexcess in these sediments. CaCO3 distribution
pattern in these sediments shows its enrichment close to the shallower elevated regions
adjacent to mid-oceanic ridge, in a highly oxic environment.
High Al/Ti ratio (>22 on average) of the studied samples indicates influence of volcanic
precursors including acidic, vitric ash and plagioclase, possibly derived from the adjacent
ridge systems and past volcanic activities in this area depicted through the presence of
numerous seamounts present in this basin. Also, the higher proportion of “excess”
aluminium (Al) adjacent to the ridge areas and fracture zones suggests that not all Al
content in these sediments were derived from the continental rocks as was considered
earlier.
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TERRESTRIAL AND MARINE PRODUCTIVITY: SOME COMMON THREADS
1
R. DaSilva, 1A. Mazumdar*, 2R.K. Joshi, 3A. Shaji, 4P. Mahalakshmi, 1B.G. Naik
1
CSIR, National Institute of Oceanography-403004, India; [email protected]
2
Geological Survey of India, Kolkata-700 091, India
3
Centre for Marine Living Resources & Ecology-682030, India
4
Flat No. CS-1, Block-C, Astral Garden, Panaji, Goa-403002
We report here high resolution vertical profiles of total inorganic carbon (TIC wt%),
and 13CTOC values from a core MD161-19 acquired off Mahanadi basin, Bay of Bengal
onboard R/V Marion Dufrense (May 2007). Based on the AMS 14C dates (generated at the
NOSAMS, Woods Hole Oceanographic Institution, USA) and 18O (G.ruber) values the
maximum depositional age of the core is estimated at ~300 ky covering 8 marine isotope
stages. The C and O isotope ratio measurement of G.ruber was carried out using a Finnigan
MAT 253 IRMS with dual inlet system at the Department of Geological Sciences, University
of Florida. The age depth model for sediment core is obtained from the correlation of δ18O
profile with the SPECMAP data. TIC measurements were carried out with an UIC carbon
coulometer. The 13CTOC analyses was carried out using a Thermo IRMS (Delta V plus)
coupled to an EA. The TIC content ranges from ~0.2 wt% to ~5 wt%. Several well defined TIC
peaks are recognized in the profile. The 13CTOC values range from -15 to -22‰ VPDB. The
13CTOC values show significant vertical variation which is linked to the nature of terrestrial
organic flux (i.e., C3 vs C4) and marine productivity. The 13CTOC values show remarkable
correlation with temporal pCO2 change. Additional effects like rainfall/ aridity and
temperature etc., possibly superimposed on the broad13CTOC variation at MIS scale.
Remarkable correlation with 12C enrichment in TOC and enhanced TIC content (high content
of foraminifera) is observed throughout the core. We presume that the increase in marine
productivity during LGM is due to increased regional aridity and decreased stratification
resulting from a weak southwest monsoon. Arid terrestrial condition resulted in
proliferation of C4 grass type vegetation. Our future study is aimed at high resolution lipid
chemistry of the organic content which will help in the understanding of the nature of
terrestrial organic loading, marine productivity variation through various marine isotope
stages.
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THE EFFECT OF HOLOCENE TEMPERATURE CHANGES ON HUMAN
SETTLEMENTS IN ASIA
Rajeev Saraswat
Geological Oceanography Division, National Institute of Oceanography, Goa; [email protected]
The rise and demise of civilizations in Asia has so far been attributed largely to
monsoon, presuming negligible effect of limited temperature variability during the
Holocene. Here, we demonstrate the unequivocal effect of temperature variations in
shaping human civilizations in Asia, during the Holocene. We have reconstructed centennial
scale quantitative changes in temperature and precipitation, covering the entire Holocene,
from a core collected from the southeastern Arabian Sea. Two intervals, viz. from 10 (9.110.6) kyr BP to 6.8 (6.6-7.0) kyr BP, and 4.5 (3.0-5.7) kyr BP to 3.3 (2.4-4.3) kyr BP, of
relatively consistent precipitation with warm conditions, are identified. The intervening
period is marked by heavy precipitation and fluctuating temperature. The first of these two
intervals coincides with the Mehrgarh civilization, and the later interval of steady
precipitation and temperature, corresponds with the Harappan civilization. A unique feature
of the record is the mid-Holocene shift in local evaporation-precipitation, which is
synchronous with an abrupt shift in monsoon induced upwelling intensity, dissolved oxygen
in seawater, CaCO3 burial, and increase in organic carbon deposition. The mid-Holocene
climate shift coincides with an increase in atmospheric CO2. The Harappan Civilization
followed the mid-Holocene climate shift, suggesting that the shift ameliorated the
conditions for the proliferation of well-developed human civilization. A subsequent drop in
temperature, coupled with an increase in precipitation, beginning at 3.3 (2.4-4.3) kyr BP,
marks the decline of Harappan Civilization, suggesting that the rise and decline of human
civilization in Indian subcontinent, was modulated by temporal changes in not only
precipitation but also temperature.
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SEDIMENT DISPERSAL AND TRANSPORT ON THE CONTINENTAL SHELF OF
MYANMAR, NORTHEAST INDIAN OCEAN
P.S. Rao and V.Ramaswamy
CSIR-National Institute of Oceanography, Dona Paula, Goa - 403004, India; [email protected]
The continental shelf of Myanmar is about 2300 km long from Bangladesh border in
the northwest to Thai border in the southeast and may be divided into three physiographic
domains - the northern Rakhine (Arakan) shelf adjacent to the Bay of Bengal, the central
Ayeyarwady shelf and the southern Tanintharyi (Tenasserim) shelf facing the Andaman Sea.
The Myanmar shelf receives sediments from some of the largest rivers in the world like the
Ayeyarwady (Irrawaddy), the Salween (Thanlwin) and the Ganges–Brahmaputra rivers. The
continental shelf of Myanmar is characterized by complex morphology, neotectonic activity,
seasonally reversing monsoon winds and coastal currents, periodic tropical cyclones and
storm surges, and meso- to macrotidal conditions.
The Rakhine continental shelf is wider in the north (~ 85 km) and narrows towards the
south (< 40 km). The shelf topography is complex due to the presence of numerous islands
and submerged shoals. The shelf break occurs at a water depth of about 100 m in the north
and shallows to about 70 m in the south. The upper part of the shelf is shallow and deltaic
while the central part is more or less rocky and devoid of sediment. The southern part
consists of silty-clays on the inner shelf and coralline sands and shell fragments on the outer
shelf.
The Ayeyarwady continental shelf is part of a complex geological setting in the
Andaman Basin. The shelf width is about 170 km off the Ayeyarwady River mouths and
increases to more than 250 km in the center of the Gulf of Martaban. Seafloor in the Gulf of
Martaban and adjacent inner shelf is generally smooth whereas the outer shelf has a rough
surface with relief of 2–20 m and has topographic features such as pinnacles, highs and
valleys, buried channels and scarps. The shelf break is at 110 m isobath, beyond which the
depth increases rapidly to about 2000 m. A well defined canyon, the Martaben Canyon,
incises the Ayeyarwady shelf and follows the N-S trending Sagaing Fault System. Three
distinct areas of sediment texture could be identified on the Ayeyarwady shelf (i) finegrained muds in the Gulf of Martaban and adjacent inner shelf, (ii) outer shelf relict sands
and (iii) mixed sediments in the Martaban Canyon. Redistribution of sediments in the
canyon by turbidity currents, gravity-driven mass flows and perhaps by tidal currents, has
resulted in the formation of mixed type sediments from silty clays in the north to sands and
silty sands in the deeper portion.
The Tanintharyi shelf is about 1200 km long aligning roughly in north–south direction.
The shelf topography is complex due to the presence of numerous islands and shoals. The
shelf break occurs at about 100m in the north and slightly deeper (110 m) in the south. A
prominent feature in the southern part of the Tanintharyi shelf is the presence of 85-140 m
wide Myeik Terrace. Sediments within the protected embayments of the Tanintharyi shelf
are mostly carbonate-rich, except for an isolated patch of fine-grained muds indicating a
local source, probably the Dawei (Tavoy) River. The Myeik Terrace is covered with muddy
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sands with subangular to rounded quartz grains, and mixed with carbonate shells and some
fine-grained material.
The major source of the terrigenous sediment to the Myanmar Continental Shelf is the
Ayeyarwady River. The sediments discharged by the Ayeyarwady River are displaced
eastwards by a combination of tidal currents and clockwise flowing SW monsoon current
and deposited in the Gulf of Martaban along with the sediments discharged by the Salween
River, forming one of largest mud belts of the world. The Gulf of Martaban experiences
perennially high-suspended sediments due to re-suspension of bottom sediments by strong
tidal currents. Part of the suspended sediment flows into the Martaban Canyon and is
transported towards the slope in the form of bottom nepheloid layers. The Martaban
Canyon acts as a conduit for sediments to the deep Andaman Sea. During the NE monsoon
period (November–January) the surface currents flow towards west transporting some of
the suspended sediments westwards into the eastern Bay of Bengal. The sediments carried
into the Bay of Bengal may move northwards by the anti-cyclonic circulation of NE monsoon
and probably reach the Rakhine shelf.
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IDENTIFICATION OF SOURCES AND FREQUENCY OF MINERAL DUST OVER THE
MIDDLE-EAST AND SOUTHWEST ASIA BY USING SATELLITE DATA.
K.Suresh*, V.Ramaswamy, C.Prakashbabu
CSIR- National Institute of Oceanography, Dona Paula, Goa-403004, [email protected]
Mineral dust plays a major role in regulating the atmospheric radiation budget, ocean
biogeochemical cycles and productivity. Deposition of the aeolian dust provides macro and
micronutrients to the surface oceans which impacts phytoplankton productivity. Major
sources of mineral dust to the Arabian Sea are the arid & semi-arid regions, ephemeral lakes
and dried lake beds of the Arabian Peninsula and SW Asia. Information on sources and the
frequency of dust events are important as composition and frequency of dust injected into
the atmosphere vary significantly in different source regions. In the presented study, a
number of satellite derived products including the EUMETSAT’s Dust RGB data and MODISAqua Aerosol Optical Depth (AOD) data have been used to identify the major dust sources
as well as frequency of dust events in this region for the period September 2012 to August
2013.
Most dust storms originate from one of these six geographic areas: (i) Syrian Desert,
(ii) flood plains of Tigris-Euphrates, (iii) Endorheic basins of Iran, Afghanistan and Pakistan,
(iv) Al-Dhana Desert, (v) Coastal region of Arabian Peninsula and (vi) Makran coast. Dust is
most likely from the ephemeral lakes, wadis, alluvial plains and coastal areas of the above
regions.
Two geographic regions frequently have dust events; one is the area comprising Syrian
Desert and flood plains of Tigris-Euphrates River in which lot of alluvium is available and the
other one is endorheic basins of Iran, Afghanistan and Pakistan where many ephemeral
lakes are situated. There are 67 dust events observed in each of the above said regions for
the study period.
References:
Banerjee, P., and S. Prasanna Kumar (2014), Dust-induced episodic phytoplankton blooms in
the Arabian Sea during winter monsoon, J.Geophys. Res. Oceans, 119, doi:
10.1002/2014JC010304.
Ginoux, P., J. M. Prospero, O. Torres, Chin, and M., 2004: Long-term simulation of global
dust distribution with the GOCART model: correlation with North Atlantic Oscillation.
Environ. Model. Software, 19, 113-128
Kaufman, Y., I. Koren, L. A. Remer, D. Tanre, P. Ginoux, and S. Fan (2005), Dust transport and
deposition observed from the Terra-MODIS spacecraft over the Atlantic Ocean, J. Geophys.
Res., 110, D10S12, doi: 10.1029/2003JD004436
Schepanski K., Tegen I., Macke A. Comparison of satellite based observations of Saharan
dust source areas, Remote Sensing of Environment 123 (2012) 90–97
doi:10.1016/j.rse.2012.03.019
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PHOSPHATE UPTAKE BY MICROBIAL COMMUNITES IN THE CONTINENTAL
MARGIN SEDIMENTS
S. S. Mamatha*, P.P.Sujith, S. Benjamin, D. Vaigankar, T. Singh, T.R.A. Thomas, B. Nagender
Nath, P.A. Loka Bharathi
CSIR-National Institute of Oceanography, Dona Paula, Goa-403004, India; [email protected]
Phosphorous is an essential element in life forms as it is a component of nucleic acid
and cell membrane. In the marine ecosystem, recycling of phosphate is rapid which makes it
a limiting nutrient in primary production as well as deposition in sediment. Microbes could
play an important role in the global phosphorous cycle as the earlier studies support their
activity towards the production of phosphatic deposits and phosphorite formations. Hence,
in the present study we tried to understand the extent of microbial uptake of phosphate
which is released by the oxidation of hypophosphite in sediment. The experiment was
carried out on a short sediment core from a topographic high off Goa, where the occurrence
of phosphatic pellets and grains containing carbon flourapatite (CFA) had been earlier
encountered. The major components in the experimental medium were 2g of glucose, 1g of
NH4Cl and 5 μM of hypophosphite (Spectrochem, AR grade) per litre of seawater. The
sediment dilutions from different subsections of the core namely 0-2, 4-6, 8-10 10-15 and
30-35 cm were used to inoculate the experimental tubes. The experimental set up was
incubated in replicates of five under suboxic conditions over a period of two years at 12±3°C
and changes in phosphate concentration was measured according to Grasshoff et al. (1983).
It was observed that there is net phosphate uptake in the sediments throughout the depth
(figure 1). The maximum uptake was at a depth of 0-2 cm followed by 8-10 cm below the
surface. There was also an increase in the cell number as the depth increased till 10-15 cm
(figure 2). Cell size ranged from 0.5 to 4 µ with an average of nearly 2 to 2.5 µ at depths
where high uptake of phosphate was observed (figure 3 and 4). The maximum cell size was
observed at 8-10 cm depth which also showed relatively high cell abundance and uptake of
phosphate. On the contrary, though the phosphate utilization was relatively less, high cell
abundance and cell size were observed at 30-35 cm depth. This could be due to
simultaneous release and uptake of phosphate by microbes in the sediment and also
increase in cell size could be linked to the accumulation of phosphate inside the cell. On the
whole, phosphate uptake, cell abundance and cell size were synchronous at 8-10 cm depth.
These observations suggest the potential involvement of microbial communities of the
continental margin sediments in the oxidation of hypophosphite, uptake and accumulation
of phosphate.
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Figure 1. Phosphate concentration at
different depths after two years of
incubation under suboxic condition
Figure 2. Cell abundance at different depths
after two years of incubation under suboxic
condition
Figure 3. Cell size at different depths after
two years of incubation under suboxic
condition
Figure 4. Bacterial cells ranged from 3-4µm
References
Sterner, R. W., and Elser, J. J. (2002), Ecological Stoichiometry: The Biology of Elements from
Molecules to the Biosphere, Princeton University Press, Princeton, NJ.
Benitez-Nelson et al. (2005), Digenetic effects on particulate phosphorus samples collected
using formalin-poisoned sediment traps. Limnology and oceanography: methods, 3, 308317.
Grasshoff et al. (1983), Methods of sea water analysis. Verlag Chemie GmbH, D-6940
Weinheim.
Lepland et al. (2014), Potential influence of sulfur bactertia on plaeoproterozoic
phosphogenesis, nature geosciences, 7, 20-24.
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COASTAL PROCESSES
SESSION - 05
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SURFZONE CURRENTS AT MIRAMAR BEACH OF GOA, INDIA: A COMPARISON
OF OBSERVATION AND THEORY
Yadhunath E.M, Jaya Kumar Seelam*, Jishad, M, Gowthaman R, Pednekar P.S
Surfzone currents are generally classified as longshore currents and cross shore
currents. In the nearshore region, longshore currents are both generated as well as affected
by breaking waves. Studies regarding longshore currents improve the knowledge about
sediment transport at that location, and changes in beach morphology. Near shore
topography also has an important role in longshore current generating mechanism, which
direct the longshore fluxes and also transforms itself according to waves and currents
(Sheremet et al., 2011). Another factor that is important in estimating the longshore
currents is the beach face slope. There are many theories which can describe longshore
current velocity. Most of the theories are based on principle of conservation of momentum
or energy; few are based on regression analysis and continuity relations. Comparison studies
of measured and estimated currents were carried out in different scenarios throughout the
world. Along Indian coastline Hameed et al. (1986) identified modified equation of LonguetHiggins (1970), herein after refereed as LH70 and Komar (1975) give better correlation with
measured data of Valiyathura and Aleppey coasts, Kerala, India. Chandramohan et al. (1992)
based on field data between Ratnagiri and Mangalore coasts on west coast of India
observed that LH70 gave 25% higher values than Galvin (1987). Kumar et al. (2000)
observed that LH70 over predicted by 32% and Galvin by 6% for the data sets from
Kannirajapuram coast, Tamil Nadu.
Yadhunath et al. (2014) measured the longshore current using RCM9 for a period of
2hr and wave parameters measured using Seabird wave and tide gauge from a single
measurement location off Candolim and Miramar beaches of Goa. Instruments were
deployed at the swash zone of depth 0.5m, in which RCM9 is buried inside the sea bed with
sensor head placed above the sea bed. These measured currents were compared with
eleven theoretical equations by applying the measured wave data. They observed that with
modified coefficients, the LH70 and Komar equations could give better result with a
magnitude range from 5-10% lesser than that of measured velocity. In the present study,
measurements were carried out at Miramar beach which include deployment of three
InterOcean S4 current meters for a period of one tidal cycle in alongshore direction in the
surf zone, with a distance of about 100m between them. At the same time co-located
RCM9 and Pressure transducers (PT) at a cross shore distance of 70m away from each S4
were also deployed in the swash zone. In this experiment the changes in alongshore and
cross shore current speed due to oblique wave action is analyzed. The measured wave
parameters are used in estimating the longshore current at this cross section using different
theoretical equations by LH70, Komar (1975), Galvin (1987), Putnam et al. (1949), Harrison
(1968), Brebner and Kamphus (1964), Inman and Quinn (1951), Bruun (1963), Fox and Davis
(1972), Pilarczyk (1999). Therefore, compared to previous study of Yadhunath et al. (2014),
this study analyzes longshore current variations over a region and estimates the longshore
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current velocity using breaking wave parameters and corresponding transformed wave
parameters in the swash zone.
References:
Brebner, A., and J. W. Kamphuis (1964), Model tests on the relationship between deep
water wave characteristics and Longshore currents., Proc. 9th ICCE, Lisbon, pp 191-196
Bruun, P. (1963), Longshore currents and longshore troughs, Journal of Geophysical
Research, 68(4), 1065-1078.
Chandramohan, P., B. U. Nayak, N. M. Anand, and V. Sanil Kumar (1992), Filed measurement
on lonshore current variation between Ratnagiri and Mnagalore, west coast of India, in
Proceedings of Eighth Conference of International Association of Hydraulic Research,
CWPRS, Pune, edited.
Davis, R. A., and W. T. Fox (1972), Coastal Processes and Beach Dynamics at Sheboygan,
Wisconsin, July, 1972.Rep., Williams College, williams town, mass.
Galvin, C. (1987), The continuity equation for longshore current velocity with breaker angle
adjusted for a wave-current interaction, Coastal Engineering, 11(2), 115-129.
Hameed, T. S., M. Baba, and K. V. Thomas (1986), Computation of Longshore currents,
Indian Journal of Marine Sciences, 15, 92-95.
Harrison, W. (1968), Empirical equation for longshore current velocity, Journal of
geophysical Research, 73(22), 6929-6936.
Inman, D., and W. Quinn (1951), Currents in the surf zone, Coastal Engineering Proceedings,
1(2), 3.
Komar, P. D. (1975), Nearshore currents: Generation by obliquely incident waves and
longshore variations in breaker heights, In: J. Hails and A. Carr (eds), 17-45.
Kumar, V. S., P. Chandramohan, K. A. Kumar, R. Gowthaman, and P. Pednekar (2000),
Longshore Currents and Sediment Transport along Kannirajapuram Coast, Tamilnadu, India,
Journal of Coastal Research, 16(2), 247-254.
Longuet-Higgins. (1970), Longshore currents generated by obliquely incident sea waves,2,
Journal of geophysical Research, 75(33), 6790-6801.
Pilarczyk, K. W. (1999), Design of Dikes and Revertments- Dutch paractise, in Handbook of
Coastal Enginering, McGraw-Hill.
Putnam, J. A., and W. H. Munk, and M.A.Traylor., (1949), The prediction of longshore
currents, Transactions, American Geophysical Union, 30, 337-345.
Sheremet, A., S. Jaramillo, S. F. Su, M. A. Allison, and K. T. Holland (2011), Wave-mud
interaction over the muddy Atchafalaya subaqueous clinoform, Louisiana, United States:
Wave processes, Journal of Geophysical Research, 116(C6) C06005,
doi:10.1029/2010JC006644.
Yadhunath, E. M., J. K. Seelam, M. Jishad, R. Gowthaman, C. Rajasekaran, and P. S. Pednekar
(2014), Surfzone currents at Candolim and Miramar beaches of Goa, India: measurements
and comparisons, Indian Journal of Marine Sciences, 43, 7.
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CHANGE DETECTION STUDIES ALONG VENGURLA COAST, INDIA THROUGH
REMOTE SENSING AND GIS
R. Gowthaman*1, Y.G. Harikrishna Sharma2 and V. Sanilkumar1
1
CSIR-National Institute of Oceanography, Dona Paula, Goa-403004; [email protected]
2
Mangalore University, Mangalagangotri, Mangalore -574199
The study area Vengurla is located in South Maharashtra near the border of Goa and is part of the
Konkan Coast. The northern coastline of Vengurla is rocky, but not in southern region. River Karli flows from
east to west and borders the northern part. River Talvada flows from north-east to south-west and joins the
sea at Mochemad. Two more rivers join the sea at the Vengurla port hill, situated on the northern and
southern sides of the hill. The shoreline is very irregular, associated with features like cliffs, notched,
promontories, sea caves, embayments, submerged shoals and offshore islands. GIS technique is used to study
the shoreline changes and Land-Use/Land Cover (LU/LC) classification of the study area utilizing the Indian
Remote sensing satellite (IRS-1D, IRS-P6 and LANDSAT-7) data during 2002, 2011, 2013, 2014 and Toposheet of
1954. Base maps are scanned and registered using ERDAS imagine software and map composition is done
2
using ArcGIS software. Long-term shoreline changes from 1954 to 2014 show accretion of 0.04 km and
2
2
2
erosion of 2.25 km . Erosion of 0.79 km and accretion of 0.45 km is observed during the short-term (20112014). The validation of the 2014 satellite data is done with field measurements using GPS. The major LU/LC
types in the study area are built-up areas, vegetation and water body. The changing trend in the land use
pattern between the years 2002, 2011, 2013 and 2014 is estimated. During 2002-2014, 0.009 % of spit area,
2.73 % of vegetation, 2.58 % of water body, 0.106 % of plantation and 1.54 % of built up area increased. During
the same period, 0.53 % of sand area, 6.22% of barren land, 0.09 % of mangroves and 0.05 % of rocky coast
decreased. Seasonal variation in accumulation and erosion is seen at Vengurla Beach, which is moderate to
very low during the pre-monsoon, high to low during the monsoon, and low to very low during the postmonsoon season.
Fig. 1 Study Area
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Fig 2. Shoreline changes from 1954 to 2014
Fig.3 LU/LC Classification in 2014
References:
Chandramohan, P. Sanilkumar, V. Nayak, B.U and Pathak, K.C. (1993) ‘ Variation of
longshore current and sediment transport along south Maharshtra coast , West coast of
Indian, Indian Journal of Marine Science, 22, 115-118p.
Praveen B. Gawali, Nathani Basavaiah, and Pramod T. Hanamgond (2010)’ Mineral Magnetic
Properties of Sediments of Beaches, Redi–Vengurla Coast, Central West Coast of India: A
Seasonal Characterization and Provenance Study’, Journal of Coastal Research , 26(3), 569579.
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UPWELLING FEATURES OFF SOMALIA AND OMAN COASTS FROM MODEL
SIMULATIONS
Tanuja Nigam*, Vimlesh Pant
Indian Institute of Technology Delhi, New Delhi-110016; [email protected]
Upwelling process in the ocean brings the colder and nutrient rich subsurface waters
to the sea surface, and thereby reduces the sea surface temperature and may increase the
biological productivity. The reduction in SST affects the regional weather, such as fog
formation and reduction in convection. In the present study, coastal upwelling features
were simulated using a hydrostatic, free surface, primitive equation ocean model Regional
Ocean modelling system (ROMS) over the northern Indian Ocean domain. The model
follows sigma coordinate in the vertical. The horizontal and vertical resolutions of model are
0.25° × 0.25° and 32 vertical levels, respectively. During Indian summer monsoon (JuneSeptember) the strong southwest winds blows over the North Indian Ocean (NIO) basin,
producing upwelling at the coasts of Somalia and Oman. The model simulations were
analyzed for the coastal upwelling off Somalia and Oman coasts. In general, the model
simulated upwelling signatures are in good agreement with the observations. The maximum
Ekman transport during July off the Somali coast, calculated from the wind forcing data
indicates higher transport as compare to the Oman coast, and up to four times larger values
than that of southwest coast of India. Moreover, there is a significant difference in the
different wind forcing data sets. The ROMS model is forced by two forcing data sets of
Comprehensive Ocean Atmosphere Data Sets (COADS) ocean surface monthly climatology
and National Oceanography Centre (NOC). The difference between NOC and COADS forcing
is about -0.008 N/m2 in the month of January and about -0.024 N/m2 in the month of July is
observed over Somalia and Oman regions. Model simulated vertical profiles of temperature
with COADS and NOC forcings are validated against the World Ocean Atlas 13 (WOA13) data
set over Somali, Oman and West Coasts. It is found that NOC simulations are in better
agreement with observed data comparative to COADS simulations. The model simulated
vertical velocity is also validated with Simple Ocean Data Assimilation (SODA) data. The
simulated magnitude (8 x 10-3 cm/sec) of vertical velocity off Somalia coast during AugustSeptember is well comparable with the observed data.
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EVALUATION OF MITIGATION OPTIONS FOR SUSTAINABLE SHORELINE
MANAGEMENT FOR POOMPUHAR COAST
Abhishek Tavva*, S Sankar, Vijaya Ravichandran, KM Sivakholundu
Sedimentation and erosion processes at a site play a key role during development of
any coastal project along the Tamil Nadu coast. The east coast of India has northerly littoral
movement for most of the time during a year due to which any obstruction to littoral
movement like breakwater placed across the shore causes accretion to the south of the
structure accompanied by erosion to the north. National Institute of Ocean Technology
(NIOT) had carried out marine Environmental Impact Assessment (EIA) study for the
proposed fishing harbour consisting of breakwaters at Poompuhar in Tamil Nadu. This paper
deals with the effects of breakwater construction on the shoreline and evaluation of various
mitigation strategies for erosion prevention.
The model for shoreline evolution for Poompuhar was setup using LITLINE module of
LITPACK. The coastline is oriented 355o to true North. The predominant wave direction was
from South-East. Modelling was carried out for a stretch of 6km with a grid spacing of 100m
along the shore. Data from both primary and secondary sources were used as inputs for the
model. Bathymetry and beach profiling data were collected by NIOT at Poompuhar and
GEBCO data for the remaining area of the domain of the model were interpolated and used.
A profile best representing the bathymetry of the area was used as input. Wave data
obtained from NIOT wave model was used as input. Sand particles of mean diameter of 150
µm was used as input for grain size. The fall velocity was calculated based on Stokes law.
The model was run for 1 year shoreline evolution in the absence of the proposed
breakwaters. Validation was carried out for shift in shoreline based on data available from
beach profiling and a close match was obtained. Model run was carried out for shoreline
evolution in the presence of proposed breakwaters for fisheries harbour. It was observed
that the shoreline undergoes severe erosion to the north in the presence of proposed
breakwaters for fisheries harbour. The shoreline undergoes erosion to an extent of 1.5km
along the shore with an erosion of 40m into the shore.
Various strategies were evaluated to mitigate the erosion to the north of proposed
breakwaters and each of these cases was modelled. One of the options was a groin field to
the north of the breakwaters. Based on model studies it was found that erosion continued
to persist northwards of the groin field. The other option was a shore parallel detached
offshore segmented breakwater which yielded better results as it showed lower erosion to
the north of the breakwaters proposed for fisheries harbour. It is therefore concluded that
offshore segmented breakwaters provide a sustainable shoreline management in the case
of Poompuhar Coast.
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EFFECT OF WIND DRIVEN CIRCULATION ON INTERNAL WAVES: A CASE STUDY
Sachiko Mohanty*, Himansu K Pradhan, A D Rao
[email protected]
Internal Waves (IWs) occur in the interior stratified region of strong density
discontinuity (thermocline/pycnocline) in the sea and are mostly generated by a flow over
topography. The variable bottom topography, the altering stratification throughout the year
and the tides make the western Bay of Bengal (BoB) an ideal region for generation of
internal waves.
MITgcm, a non-hydrostatic, 3D z-coordinate primitive equation model is configured
over the western BoB to study IW characteristics during November-December 2013. A high
resolution mesh extending from 15°N to 20°N and 82°E to 87°E is prepared from GEBCO (30
sec) dataset with an horizontal extent of 270km and 520km towards east and north
directions respectively. The resolution in the offshore direction varies from 200m near the
coast to 1500m in the open ocean while the resolution is about 3km along the coast. The
model is initialized with density fields calculated from the monthly climatology of
temperature and salinity from WOA09. The model is forced by the real-time surface wind
stress from the daily ASCAT for the months of November and December 2013. For the IWs
simulation, the dominant tidal constituents over the BoB namely M2, S2, K1 and O1 are
derived from the global tidal model TPXO7.2 and incorporated to the MITgcm model at the
eastern boundary. The model integration is continued for 2 months and the results for
surface currents and vertical temperature are compared with OSCAR and ARGO datasets
respectively for the months of November-December. During this period, the currents are
towards the south (EICC) which is simulated well in comparison with OSCAR currents. The
model reproduces the temperature inversion of about 0.5°C well present in the ARGO data
off Gopalpur and Kalingapatnam. In-situ temperature, salinity and current data were
collected off Gopalpur for two locations where station depths of 110m and 400m during
November and December. These ADCP, Microcat, RCM, TP sensor data are available at
various depths which are used in computing the spectral analysis for identifying IWs
characteristics. The spectral estimate of model simulated density is compared with the insitu data. It is observed that the spectral estimates are in good agreement with the
observations for both the locations.
The experiments are also made without wind forcing and compared with the
simulations with wind. The conclusions are drawn on the effect of currents on the internal
waves at different cross-sections based on the spectral estimates computed from the
density.
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VALIDATION OF STORM SURGES USING A COUPLED SURGE-TIDE-WAVE
MODEL: A CASE STUDY FOR TAMIL NADU COAST
Smita Pandey*, Jismy Poulse , A D Rao
[email protected]
India is frequently affected by tropical cyclones which are among the most lethal and
costly natural hazards affecting humankind. Coastal flooding as a response of storm surges
associated with tropical cyclones is one of the greatest vulnerability that occurs along the
coast. A proper understanding of the factors responsible for generating and its contribution
to the total water elevation along the coast is highly desirable. The rise of total water
elevation at the coast is caused primarily by three factors that include storm surges, tides
and wind waves.
For this study, a hydrodynamic finite element based Advanced Circulation 2D depth
integrated (ADCIRC-2DDI) model is used to compute storm surges and water levels along the
Tamil Nadu coast considering the non-linear interaction with the tide. ADCIRC solves
equations of motion of a moving fluid to compute velocity and elevation that can be
obtained from the solution of continuity equation. The modeling of storm surges in
complex terrain requires true representation of coastal geometry as well as detailed
onshore topography and bathymetry. For this purpose, the bathymetry of the domain is
derived from the latest available GEBCO dataset with a resolution of 30sec (900m) and
topography from SRTM (90m). The surface wind associated with tropical cyclone is the main
driving force for storm surges. The cyclonic winds are calculated by using a dynamic storm
model of Jelesnianski and Taylor (1973). Tidal forcing along the open boundary is derived
from FES2004 database. The model is coupled with the SWAN model in order to study the
impact of wind waves on the storm surges. The experiments are performed to validate the
total water elevation generated for three cyclonic cases: Cuddalore 2000, Thane 2011, and
Nilam 2012 cyclones with available tide gauge data during this period. On comparison of
model surge residuals with the observed ones, it is inferred that the contribution of wave
set up caused by wind waves plays an important role on the total water elevation. The
significance of each factor responsible for the computation of total water elevation is
highlighted.
References:
Jelesnianski CP, Taylor AD (1973) NOAA technical memorandum. ERL, WMPO-3, p 33
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EVIDENCES OF HIGH ENERGY MARINE EVENTS FROM THE GUJARAT COAST,
WESTERN INDIA: STORM OR TSUNAMI DEPOSITS?
S.P.Prizomwala1*, Drasti Gandhi1, 2, N.P. Bhatt3, B.K. Rastogi1
1
Institute of Seismological Research, Raisan, Gandhinagar 382009, India; *[email protected]
2
The Geology Department, M. G. Science Institute, Navrangpura, Ahmedabad 380009, India
3
Department of Geology, The M. S. University of Baroda, Vadodara 390002, India
The east coast of India has been highlighted as most prone to major marine
inundations as evidenced by recent tsunamis. Presence of tsunamigenic sources in northern
Arabian Sea namely Makran Subduction Zone (MSZ) and Owen Fracture Zone (OFZ) qualifies
the west coast of India to hold signatures of past tsunamis. However the western coast of
India has remained deprived of any such studies. Here we present geological evidences of
palaeo-storm / palaeo-tsunami from the coastline of Gujarat. The Kachchh coast shows
presence of palaeo-tsunami dating back to 1000 AD in the form of sand layer sandwiched
between mud layers from Mundra and Bhadreshwar. The sand layer shows basal erosional
contact with the mud layer, lack of sorting in sediments and broken microfossils. Similarly
large boulders are found in imbricated and scattered forms on the rocky southern
Saurashtra coastline. The numerical modelling shows these boulders were derived from
offshore with a wave of 3.5 m of wave height at the shoreline. OSL dating suggests this
event dates to a period within last 3436 ± 234 years. The source for palaeo tsunami sand
layer in Kachchh is more likely an event at Strait of Hormoz / Makran Subuction Zone and
for boulder deposits of southern Saurashtra segment is the Southern Oven Ridge. We
postulate an earthquake along Makran Subduction Zone and a mega-landslide along
southern Saurashtra coastline as causal mechanism for these palaeotsunami events.
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PERFORMANCE OF DELFT3D-WAVE MODULE IN THE NEAR-SHORE WAVE
TRANSFORMATION OFF RATNAGIRI, WEST COAST OF INDIA
Glejin Johnson and V. Sanil Kumar*
CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004 India; [email protected]
Waves are the dominant factor influencing the nearshore processes .Wave refraction
and wave breaking are responsible for large fluid motions not only to drive currents,
sediment transport and bed changes but also influence the surf zone heat budget and air
bubble entrainment. Long-term in-situ measurements in the nearshore and surf zone are a
tedious task due to heavy fishing and biofouling in the area. In this study, we investigate the
performance of nearshore transformation off Bhatya beach, Ratnagiri using Delft3d-wave
module (Delft Hydraulics, 2011) developed by WL∣Delft Hydraulics. This model is an adapted
version of the SWAN model (Booij et al., 1999) which takes the effects of complicated
interactions and transformations experienced by waves propagating through space:
refraction due to bottom and current variations, shoaling, blocking and reflections due to
opposing currents, transmission/blockage through/by obstacles, effects of wind, white
capping, depth induced wave breaking, bottom friction and non-linear wave–wave
interactions. Wave data collected off Ratnagiri at 14 m water depth using Directional wave
rider buoy is used as source at boundary for the numerical modelling. Different cases are
simulated by including different physical processes. Wave data for validation of nearshore
wave transformation model is measured using the InterOcean S4DW wave gauge for a
period of one week each during the onset of summer monsoon in May 2012 and postmonsoon period in November 2012. The average significant wave height during May was
0.9 m and was 0.5 m during November. The model results show satisfactory (r ~0.7) results
with measured wave data. Due to the presence of irregular coastal landforms and
dominance of wind-sea over swells by the local wind system in the study area, the
sensitivity analyses carried out show that besides the wave input inclusion of the tide and
wind input improves the model output.
References:
Booij, N., R. C. Ris, and Leo H. Holthuijsen.(1999) A third‐generation wave model for coastal
regions: 1. Model description and validation, Journal of Geophysical Research: Oceans 104,
C4, 7649-7666.
Delft Hydraulics (2011). Delft3d User Manual. Delft. The Netherlands.
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MODELLING THE BIOLOGICAL ACTIVE LAYER CIRCULATION IN THE SOUTHEASTERN ARABIAN SEA
Vijay Kumar
Centre for Atmospheric Sciences; Indian Institute of Technology Delhi; New Delhi 16, India
Biological active layer (upper layer of Ocean) circulation plays important role for the
marine ecosystem. Most of the biological activities happen in the upper layer and circulation
influence transportation and population dynamic of plankton and forage fish. It is mainly a
wind driven circulation. The surface winds blow from the northeast during the winter
monsoon (November to February) and from the southwest during summer monsoon (May
to September). This semi-annual reversal of winds influences the surface layer of the basins
and generates a seasonal cycle in sea surface currents. Salinity and density of Upper Ocean
are nearly constant. The mixed layer of ocean can be considered as homogenous and the
depth of mixed layer in the Arabian Sea is between 20-100 m.
The shallow water equations are used to simulate the upper ocean circulation. As a
case study, the shallow-water model is applied to the South-eastern Arabian Sea (4°12’N to
19°48’N and 65°30’E to 81°51’E) along the west coast of India. The region is important
because of the high prevalence of plankton and forage fish that is highly influenced by the
reversal monsoonal currents. The model is forced by the seasonally varying surface winds.
Finite difference schemes are used for performing numerical experiments. The simulation
the upper ocean circulation mainly depends upon the horizontal turbulent viscosity besides
the input surface wind stress. Input data of wind stress for the domain of study are taken
from
the
website
of
INCOIS
(http://las.incois.gov.in/thredds/dodsC/las/idquick_daily/data_home_las_datasets_quick_daily.nc.jnl). The model simulated results are
well validated with INCOIS data of ocean current available on the website
(http://las.incois.gov.in/thredds/dodsC/las/id-57b2fa3cc8/data_home_las_
datasets_ocean_analysis_NRIG_uv_5day.nc.jnl).
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TIDAL INLET CLASSIFICATION ALONG THE COASTS OF GOA AND KARNATAKA
M. Vikas1, Jaya Kumar Seelam2*, Subbarao1
1
National Institute of Technology Karnataka, Surathkal, India
2
Tidal inlets are openings along the shore that connect the open ocean with the river,
bay or lake system over the land. Tidal inlets play a greater role in regulating the flow
between the water bodies over the land and the open ocean. Choking of these tidal inlets
could cause major flooding of the rivers and also results in reduced flow of sediments in the
open seas which results in changes of near shore sediment transport. In order to
understand the behaviour of the tidal inlets, these are classified based on their morphology
and also based on the major forces acting on the inlets.
In this study, an attempt has been made to classify these inlets based on
hydrodynamics (Hayes, 1979) and also based on dimensionless parameters using the wave
height, river discharge and Tidal prism (Thuy, 2013) for different seasons. A database was
compiled for 38 inlets along the coasts of Goa and Karnataka (Fig. 1). The database contains
spring tidal range, the average near shore significant wave height, and river discharge for
certain inlets and the bay or lagoon areas. The tidal inlets are classified considering the
variation in wave heights averaged annually, during North-East monsoons, during SouthWest monsoon and during fair weather season. It is observed that a tidal inlet can fall into
the category of tide dominated with barrier formation during certain time of the year
whereas they fall into wave dominated during other times. This kind of variations in the tidal
inlet classification could mean that tidal inlets should not be generalised for the whole of a
region without considering the morphological and hydrodynamic settings and its variations
with seasons. This paper presents the methods and results of the tidal inlet classification
along the coasts of Goa and Karnataka.
Fig. 1 Location map of the field investigations
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References:
Hayes, M. O. (1979), Barrier island morphology as a function of tidal and wave regime. In:
Leatherman, S. (ed.), Barrier Islands, from the Gulf of St. Lawrence to the Gulf of Mexico, Academic,
New York.
Thuy, V. T. T. (2013), Aspects of Inlet Geometry and Dynamics, The University of Queensland,
Brisbane, Australia.
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A STUDY ON SEASONAL MORPHOLOGICAL CHANGES AND CLASSIFICATION OF
TIDAL INLETS ALONG GUJARAT AND KERALA COASTS
N. Amarnath Reddy1*, M. Vikas1, Jaya Kumar Seelam2, Subbarao1
1
National Institute of Technology Karnataka, Surathkal, India; [email protected]
2
CSIR-National Institute of Oceanography, Goa, India
A tidal inlet is an opening in the shoreline through which water penetrates the land
thereby providing a connection between the ocean and bays, lagoons, marsh, and tidal
creek systems. The tidal inlet morphology has to be examined and studied to understand
the near shore coastal processes. The tidal inlets are classified to know the type of
dominance and to find if this changes with time. Also, inlet migration and closure are the
two factors that are strongly influenced by seasonal variation in wave climate. Some of
them are found changing when the seasonal variation of wave height is taken into
consideration. This classification, in a broader view is necessary for the management of tidal
inlets. The type of dominance over the tidal inlets in Gujarat is found very different for
northern and southern parts of the state. In this paper geo-morphological, hydrodynamic
and classification based on few dimensionless parameters has been done. In this study, two
regions of contrasting tidal and wave regime i.e., Gujarat and Kerala coasts, along the west
coast of India are considered. Gujarat coast has macro-tidal regions with mild to moderate
wave climate whereas Kerala coast experiences micro to meso tidal range with high wave
climate. Under these contrasting oceanographic regimes, the tidal inlets and their behaviour
are varied.
Classification of these inlets based along Gujarat and Kerala coasts (Fig. 1), for
different seasons, is carried out based on two methods, (i) based on hydrodynamics of the
region (Hayes, 1979) and (ii) based on non-dimensional parameters obtained from the wave
height, river discharge and Tidal prism (Thuy, 2013). A total of 63 inlets were considered in
Gujarat and 68 inlets were considered in Kerala. A database on the tidal range, near shore
significant wave height at about 10m water depth and river discharge details, if available
and the size of bay or lagoon. This paper presents the methods and results of the tidal inlet
classification carried out for inlets along the coasts of Kerala and Gujarat.
Fig. 1 Location map of the field investigations
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References:
Leatherman, S. (ed.), Barrier Islands, from the Gulf of St. Lawrence to the Gulf of Mexico,
Academic, New York.
Thuy, V. T. T. (2013), Aspects of Inlet Geometry and Dynamics, The University of
Queensland, Brisbane, Australia.
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MORPHOLOGICAL CHANGES DUE TO DEVELOPMENTAL ACTIVITIES AT
PARADIP PORT
S.G. Manjunatha*, K.B. Bobade, M.D. Kudale
Central Water & Power Research Station, Khadakwasla, Pune-411 024; [email protected]
For the development of the port on the open coast, provision of long breakwaters for
ensuring wave tranquility in the harbour is essential. The breakwaters cause obstruction to
the littoral transport. As a result, excessive accumulation on the up-drift side and severe
erosion on the down-drift side of the breakwater are inevitable. An artificial lagoon type
harbour at Paradip (Photo-1) located on the East Coast at Lat. 20°16'N, Long. 86°40'E is one
of the twelve Major ports of India which caters to large portion of the sea-borne trade of
the northeast part of the country. The port is provided with two breakwaters to provide
desired tranquility in the harbour area, ‘South breakwater’ with the present length of
1517m and the, ‘North breakwater’ with a length of 538m. The construction of the
breakwaters was completed by the year 1965 up to a length of 1217m for southern
breakwater and 538m for north breakwater. The 300m extension of south breakwater for
providing wave tranquility in the ship stoppage reach and mitigating sand encroachment in
the navigation channel was implemented during 1999 to 2013. The port became operational
on 18th April 1966.
Sea-wall
North Breakwater
South Breakwater
Accumulation of sand
Photo-1: Imagery of Paradip Port
Prior to the development of port, the yearly littoral drift was estimated to be 1.5
million cum from south to north and 0.5 million cum from north to south. Initially, beach
nourishment of the northern shoreline was not easily possible due to various difficulties like
damage to sand pump, non-availability of dredgers having shore pumping capability.
As a result, severe erosion occurred on the northern shore. In order to protect
property, a sea-wall construction started in 1970 and total length of 6000m has been
constructed. Over the years, due to severe wave action on the seawall, excessive deepening
has taken place in front of seawall. The bypassing of sand from sand trap to northern
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shoreline was possible to a very limited extent due to wave disturbance at sand trap and
inability of the dredgers to approach the northern shore, which was not able to form the
beach on permanent basis. As such, there is a need for adequate beach nourishment. The
analysis of hydrographic charts and dredging/sand bypassing details supplied by the Port
Authority indicated that, large changes in shoreline and amount of littoral drift has taken
place and it was also noted that large amount of sand was deposited during the each
cyclone at various locations in the port. This paper highlights the changes in the shoreline
and utility of the sand obtained from capital and maintenance dredging operation for shore
protection.
References:
Ananth P. N., Sunder V. (1990) ‘Sediment budget for Paradip Port, India’ Ocean and
shoreline Management, 13 (1990), pp69-91
Basco, D. R. (1983), Surfzone currents, Coastal Engineering, 7(4), 331-355.
Report on ‘Morphological and nautical studies for the extension of the port of Paradip’,
Delft Hydraulic Laboratory, 1969
Report on ‘Study of siltation process at Paradip port’, Central Water and Power Research
Station, 2008.
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PREDICTION OF SHORELINE DYNAMICS USING GEOSPATIAL TECHNOLOGY: A
CASE STUDY OF ENNORE COAST, TAMIL NADU, INDIA
S. Saravanan1*, R. Manjula2, S. Sivaranjani1
1
National Institute of Technology Tiruchirappalli, [email protected]
2
Bharathidasan University, Tiruchirappalli.
The shoreline is one of the most important feature of the coastal eco system. Various
geological processes like erosion, deposition, sedimentation, periodic storms, flooding and
sea level rise are affecting the shoreline dynamics. A recent study using multi-temporal
Landsat imagery of the Ennore coast indicated significant variation in erosion and accretion
trends from 2000 to 2013. The shoreline changes is studied by using satellite and field data
along the Ennore to Adayar creek. The base map was prepared using Survey of India toposheets on 1:50,000 scale. An integrated approach comprising visual image interpretation
and maximum likelihood supervised classification have been employed to classify the
coastal landforms by using LandSat and IRS P6 LISS-IV data for the period of 2000-2013.
In this study, an analysis was made to quantify the extent of erosion and accretion of
the Ennore to Adayar coast in Tamilnadu, India and predicts the dynamics in the future.
Shorelines were demarcated by using the End Point Rate (EPR) method in the Digital
Shoreline Analysis System (DSAS) extension in ArcGIS® and Remote Sensing techniques. The
rate of shoreline change were calculated for 500 transects generated at 100 m intervals
along the entire study area shoreline in order to determine the statistics of net shoreline
movement and shoreline change envelope by the Linear Regression of Rate of Change. It is
found that the shore line changes observed during the period of 2000 to 2013 ranges from
5.0 to 37.8 meters.
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TIDE MODULATION OF SURFZONE WAVES OFF MAHARASHTRA COAST ON
THE CENTRAL WEST COAST OF INDIA
M. Jishad*, Jaya Kumar Seelam
CSIR-National Institute of Oceanography; AcSIR, School of Oceanography, Goa; [email protected]
Tidal modulation of wave height not only impacts recreational surfers but also has
serious ramifications in the area of near shore sediment transport (Davidson et.al., 2009).
Most of the numerical models neglect the effects of tidal variation on sediment transport.
Not many field studies exist pertaining to surfzone wave height variation with tides. This
study aims at providing insight into the modulation of surfzone wave heights during a falling
tide in outer surfzone. The surf zone wave characteristic studies were carried out using
Wave Rider Buoy (WRB) and Wave and Tide Gauge (WTG) over a period of 6 hours off
Vengurla beach, Maharashtra, located on the central west of India. These WRB and two
WTG s are deployed at 3 locations in the cross-shore direction at 10m, 5m and 3m water
depth respectively in the cross-shore direction (Fig. 1). Wave characteristics analysed using
FFT at low tide, mid tide and high tide for all the locations. The variation of the spectra and
the derived parameters in terms of energy, wave steepness, etc., at each location with
respect to the tide is studied. A cross-spectral analysis of the wave height time series, tidal
displacement and dissipation of wave energy in the surfzone is also studied.
The cross-shore wave height variation is modelled using SWASH (Zilema et.al., 2011) A non-hydrostatic numerical model. SWASH is capable of simulating free surface flows and
rotational flows. The wave spectral simulations are carried out over the bathymetry, which
is used to simulate the wave propagation and to estimate the dissipation rate.
Fig. 1. Location map
References:
Davidson, M. A., T. J. O’Hare, and K. J. George (2009), Tidal modulation of incident wave
heights: Fact or Fiction?, Reef Journal, 1(1), 16-32.
Zijlema, M., G. Stelling, and P. Smit (2011), SWASH: An operational public domain code for
simulating wave fields and rapidly varied flows in coastal waters, Coastal Engineering,
58(10), 992-1012.
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SPRING-NEAP VARIABILITY IN RESIDUAL FLUXES THROUGH COCHIN INLET
Vinita J*, Revichandran C., Muraleedharan K.R., Lallu K.R., Jineesh V.K.
CSIR-National Institute of Oceanography, Regional Centre, Dr. Salim Ali Road, P.B.No.16161, Kochi, Kerala;
[email protected]
Interactions across the land-ocean boundary are currently the focus of regional and
global research to quantify fluxes of materials from the land to the coastal region which
determines the anthropogenic effects on the coastal environment (Lane et al., 1997, Jay et
al., 1997). With the advent of Acoustic Doppler Profilers (ADPs) more accurate estimation of
cross sectional fluxes is far accomplished in unsteady and bi-directional flow conditions of
estuaries. This paper reports for the first time the discharge measurements conducted
across Cochin inlet using ADP to examine the spring-neap variability in residual fluxes of
water and nutrients during dry season.
Figure 1. Map of Cochin estuary and Cochin inlet. Transect sampled across inlet using ADP
and CTD sampling station is shown.
A 24-h field experiment was carried out at Cochin inlet for two consecutive tidal cycles
of neap (22-23 February 2010) and spring (1-2 March 2010) tides during the least runoff
period (Figure 1). Water level was recorded at 10 minute intervals using SBE 26 plus Tide
Recorder with accuracy 0.1% of full scale (Strain Gauge Pressure) which was installed at the
sampling cross sections. A Sontek ADP (1500 kHz) with bottom track capability was towed
across the inlet for every hour which acquired vertical velocity (± 1 % accuracy) profiles at 5s
averaging rate and 0.9m of vertical resolution (cell size). Downstream currents are assigned
positive and upstream currents are assigned negative. The discharge computations were
made using the proprietary software Sontek’s River Surveyor. Salinity profiles were taken
using SBE Seabird 19 plus CTD (conductivity ± 0.001 Sm−1) with a bin size 0.2 m for every one
hour interval at the middle of the transect (depth of 10 m) (Figure 1). Current profile at this
CTD sampling station was extracted from the ADP cross-channel data to examine the
evolution of currents and stratification over tidal cycles. Using this data, the gradient
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Richardson number (Ri), which provides stability of the water column were computed from
equation,
------------------ (1)
(
)
At the same location, water samples were also collected from the surface and bottom
for 3 h intervals for both tidal phases. Water samples for various dissolved inorganic
nutrients (Nitrite, Nitrate, Ammonia, Silicate, Phosphate) were filtered and analyzed within
3h of sampling using a UV-VIS Spectrophotometer (Shimadzu 1650PC) according to the
methods described in Grasshoff et al. (1983). Nutrient transport at instantaneous discharge
values were multiplied by the corresponding nutrient concentration. Net fluxes are
represented in tons per day (t d-1).
The maximum tidal range for neap tide was 75.4cm which increased to 93.9cm for
spring tide. Pronounced diurnal inequality was observed for neap tide particularly during
low tides (36.9cm). The currents were vertically homogeneous and were unidirectional for
both tides. The salinity field under neap tides showed stratification during ebb (Ri ~ 0.9) and
well mixed water column during peak flood (Ri ~ 0.3). During spring tide, there was
turbulent mixing and Ri values were less than 0.25 throughout the observation period.
From cross-channel measurements, during neap the maximum mean velocity
obtained was 98 cm.s-1 in the ebb direction (270°). In the flood direction (90°), the maximum
mean velocity was 68 cm.s-1. During spring, the maximum ebb and flood currents were
96cms-1 and 84cms-1 respectively. The computed residual fluxes of water over the tidal
cycles were 4990.8 m3s-1 and 2149.7 m3s-1 for neap and spring tides respectively, directed
seaward during both tides.
Generally, the computed net nutrient fluxes were all positive, indicating export of
filterable nutrients into the sea. Ammonia fluxes were the highest which showed positive
fluxes during neap while negative fluxes during spring tides. The export fluxes of DIN and
silicate of Cochin estuary were larger compared to the estimates from other Indian
estuaries. The intense flushing caused by strong ebb currents compounded with the
increased nutrient concentrations during ebb resulted in the export of all nutrients into the
sea. The findings of this study highlight the consequences of anthropogenic interventions in
the estuary and their effects on the fluxes on ecologically relevant substances.
References:
Lane, A. et al., (1997), Measuring fluxes in tidal estuaries: Sensitivity to instrumentation and
associated data analyses, Estuarine, Coastal and Shelf Science, 45, 433-451.
Jay, D. et al., (1997), A review of recent developments in estuarine scalar ﬂux estimation,
Estuaries, 20, 262-280.
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VARIABILITY OF SUSPENDED SEDIMENT CONCENTRATION AND ITS TIDAL
INFLUENCE IN THE GULF OF KACHCHH, INDIA
R. Ratheesh*, A.S. Rajawat, R. Smitha
Geo-Sciences Division, Space Applications Centre, Ahmedabad; [email protected]
Empirical Orthogonal functional (EOF) analysis also known as Principle Component
analysis has been used widely on ocean data to describe the spatial properties and temporal
dynamics of different ocean features (Hernandez-Guerra and Nykjaer, 1997). In the resent
study, complexity of the temporal sediment variability within the Gulf of Kachchh is resolved
into major modes of variations using EOF analysis. Suspended sediment concentration (SSC)
derived Ocean Colour Monitor (OCM) is used to study the temporal variations in Gulf of
Kachchh (GoK) and to investigate the hydro-meteorological parameters influencing the
temporal variability of SSC. Temporal EOF analysis has been performed on sequential OCM
derived SSC subsuming the area over GoK region during the spring inter-monsoon season of
2011. Variance accounted collectively by the first four modes is around 80% (Table 1) and
the principle component (PC) of each mode, representing the temporal variations is
correlated with different hydro-meteorological parameters influencing the hydrodynamics
of the gulf (Fig. 1).
Fig.1 Different modes of PC and its comparison with ocean state parameters a) PC1
comparison with averaged tidal current speed between consecutive OCM observation (PC1
is also compared with temporal variation in the mean SSC); b) PC2 comparison with the
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instantaneous tidal height; c) PC3 comparison with instantaneous wind speed component to
the axis of GoK; d) PC4 comparison with instantaneous tidal current speed
The hydro-meteorological parameters are classified in the order of precedence of
influencing the sediment dynamics of the region. PC1 contributing 50% of the total variance
is statistically correlated with average of the simulated current velocities between
consecutive images, indicating the variation of tides from neap-spring ranges (r2=0.86)
(Table 1). During spring tides, strong tidal currents induce re-suspension of sediments
causing SSC values to increase while during neap tides, deposition of SSC occurs under weak
currents, reducing suspended sediment within gulf. PC2 contributing 20% of the total
variance has been correlated with the tidal height at the time of OCM pass (r2=0.93), where
during high tide, sediment loaded water are flooded into the gulf while during low tide,
sediment rich water are drained out of the gulf. Component of wind along the axis of the
Gulf is co-related with PC3 (r2=0.69), which contribute 6% of the total variance while PC4
(4%) is co-related with the tidal currents (r2=0.59) at the time of OCM pass.
Table 1 Percentage of variance accounted by the EOF modes and comparison of different
modes of PC with the ocean state parameters and its correlation coefficient
PC
mode
Percentage
Cumulative
percentage
Comparison with
Correlation
coefficient
PC1
50.4
50.4
Average of the current speed
(Prevailed between two OCM
passes)
0.86
PC2
19.3
69.7
Tidal height (At the time of OCM
pass)
0.93
PC3
6.3
76
Wind (At the time of OCM pass)
0.69
PC4
3.8
79.8
Current speed (At the time of OCM
pass)
0.59
The present work has sequenced the ocean state parameters in the order of their
importance in influencing the suspended sediment variability. The temporal variation in SSC
is largely depended on the current conditions that have been prevailing within the gulf
(spring and neap) while the transient current speeds at the time of OCM pass have smaller
influence to the sediment dynamics. The sediment re-suspension and deposition processes
will commence on increase or decrease in the current speed but to have an impact on the
total sediment concentrations within the gulf, the characteristic speed of the current should
sustain for a considerable duration and hence the duration of the current conditions is an
important factor in relating to the sediment dynamics. Next in the order of influence is the
tidal height at the time of OCM pass, which determines the volume of water within the
controlled volume of the gulf. Tidal height is followed by the contribution of the wind, which
is observed to have a subtle role in the temporal dynamics of the sediment concentrations.
Deposition of the suspended sediments and its re-suspension during respective favourable
conditions is the pivotal process while studying the sediment dynamics of the gulf. With
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respect to the temporal variability of the sediment concentration, GoK, during the spring
inter-monsoon period, can be considered as a self sustained system, where the sediment
are deposited and re-suspended within gulf.
References:
Hernandez-Guerra, A. and Nykjaer, L. (1997), Sea surface temperature variability off northwest Africa: 1981-1989. International Journal of Remote Sensing, 18, 2539-2558.
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AN EVALUATION OF FACTORS CONTROLLING DECADAL-SCALE SEA LEVEL RISE
IN THE MACRO-TIDAL GULF OF KACHCHH
Onkar S. Chauhan
CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004 India; [email protected]
The short and long term changes in the trend of the sea level, derived from the
available tide gauge date, have been obtained for the Gulf of Kachchh for vulnerability
assessment. We have found a large spatiotemporal variability in the sea level within the
gulf. At the mouth of the gulf (at Okha), the sea level rise was found to be 1.48 mm yr-1,
which was higher compared to Mumbai (~ 0.77 mm yr-1) and that of Karachi (0.61mm yr-1 ).
The long term rate of sea level rise at the head of the gulf (Kandla) was found to be higher
(2.85 mm yr-1) compared to that at the mouth. Wadinar station located in the middle gulf
(which had a short data span from 2005-2010), was found to have sea level rise of 24.24
mm yr-1. Considering a reported local GIA rate of 0.48 mm yr-1 for this region, the averaged
long term rate at Kandla (Okha) works out to be 3.33 (1.96) mm yr-1, and that is several fold
higher than global trend. The decadal-scale sea level variability was found also to be several
folds higher, and it varied significantly from the head (-7.33 - 24.18) to the mouth (-7.689.50 mm y-1). The temporal variability in the sea level rise had been evaluated vis-a-vis
historical events of seismic activities.
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PRELIMINARY RESULTS OF RADIANT HEATING RATE OF THE COASTAL AND
ESTUARINE WATERS OF GOA
Priya Rauth1*, T Suresh1, Prakash Chauhan2, Arvind Sahay2
1
2
Space Application Centre, ISRO, Ahmedabad, India
Solar light on the earth is the natural source of energy and plays a vital role in
controlling the biogeochemical and physical processes of the coastal waters. The solar
heating in the water column is controlled by the bio-optical properties. [Lewis et al., 1990,
Ohlmann, 2003, Sathyendranath et al., 1991]. Study of radiant heating rate (RHR) is
meaningful in the coastal and estuaries due to relatively shallow mixed layer and high
absorption due to CDOM, chlorophyll and detritus. Here results of the radiant heating rate
evaluated within one meter of water column of the coastal and estuarine waters of Goa
(India) for the year 2010 to 2011 are presented, along with its effect on the bio-optical
parameters. The studies have been carried-out using the in-situ measured, optical and
physical parameters derived from the radiative transfer simulations.
The temperature and salinity showed characteristics typical of such waters with
horizontal gradations with temperature increasing from the coastal waters towards the
head of the estuary (26.49 - 31.73°C) and the salinity was nearly invariant in the coastal
waters and decreased towards the furthest in the estuary (12.68 - 35.04 psu). The two
parameters used to derive the radiant heating rates, specific heat (Cp) and density of water
(ρ) which are often considered constants for the calculation of radiant heating rate, (Cp =
4100 J/kg°C and ρ = 1022 kg/m3) were found to vary from the coastal to estuarine waters
due to the gradients observed in the salinity and temperature. The density in these waters
varied from 1005.25 to 1022.38 kg/m3 and Cp varied from 4002.92 to 4116.42 J/kg°C. These
parameters varied while moving towards the head in the estuary and were nearly invariant
in the coastal waters with a mean value of Cp = 4008.88 J/ kg°C and ρ = 1021.29 kg/m3 ).
The spectral solar irradiance measured was used to obtain the spectrally integrated
solar radiation for the visible or PAR region (400-700 nm) and the mean value was 348.74 ±
84 W/m2. For the visible solar transmission in water column of one meter a minimum and
maximum value of 28.29 % and 72.20 % with mean of 52.77 % was observed. The radiant
heating rates for the visible range of solar radiation within one meter of water column were
within a range of 0.052 to 0.222 °C/hr with a mean value of 0.128 °C/hr. RHR was found to
increase from coastal waters towards the head of the estuary. [Fig. 1]
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Fig. 1. Variations of RHR in the coastal and estuarine waters.
Various bio-optical parameters such as absorption, scattering, diffuse attenuation,
CDOM and chlorophyll were also studied to look at their effect on the radiant heating rates
in the visible range. The radiant heating rates were found to be controlled primarily by the
optical property of absorption. It also showed linear relation with radiant heating. Similarly
the chlorophyll fluorescence and CDOM apparently followed the trend of absorption. [Fig. 2]
Fig. 2. Variations of RHR and absorption (a (440)) and chlorophyll fluorescence (Left) and
RHR and absorption (a (412)) and CDOM (Middle) and RHR and diffused attenuation
coefficient (Kd (490)) and back scattering (bb(650)) (Right).
Since absorption was found to correlate with scattering, the total scattering, back
scattering and diffuse attenuation coefficient were also found to correlate linearly with
radiant heating rate.
References:
Lewis, M. R., M. E. Carr, G. C. Feldman, W. Esaias, and C. McCain (1990), The influence of
penetrating irradiance on the heat budget of the equatorial Pacific Ocean, Nature, 347, 543545.
Ohlmann, J. C. (2003), Ocean Radiant Heating in Climate Models, Journal of Climate, 16,
1337-1351.
Sathyendranath, S., A. D. Gouveia, A. R. Shetye, P. Ravindran, and T. Platt (1991), Biological
control of surface temperature in the Arabian Sea, Nature, 349, 54-56.
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NEARSHORE CURRENTS OF AN UPWELLING REGION, SOUTHWEST COAST OF
INDIA
V.K. Jineesh*, C. Revichandran, K.R. Muraleedharan, K.R. Naveen Kumar
CSIR-National Institute of Oceanography, Regional Centre, Dr. Salim Ali Road, Kochi; [email protected]
The nearshore circulation and structure of the upper ocean along the southwest coast
of India (SWCI) during pre-monsoon are described. The near-shore environment of the West
India Coastal Current (WICC) is dominated by an equatorward flow and a shallow ekman
dynamics. Shoaling isolines of temperature, salinity and sigma-t revealed the onset of
upwelling off Kollam. Upwelling filaments as characterized by AVHRR images and
hydrographic sections have appeared to be advected only 7 km offshore at 9° N. Near shore
currents in the region is significantly influenced by the seasonal wind.
Data on currents and sea level were collected off Kollam (T1) and off Kannur (T2)
(Figure 1) for a month during April-May 2006. Currents were measured using Aanderaa selfrecording current meters (RCM-9 type) on the inner shelf within the 20 m isobaths. An SBE
Seabird 911 plus CTD onboard FORV Sagar Sampada was used to obtain temperature,
salinity and potential density (sigma-t) profiles in the study region. Stations were distributed
along two zonal transects at Kollam (9° N) and Kannur (12° N). Daily wind speed and
direction deduced from QuikSCAT satellite were used to study the influence of wind on
coastal currents at T1 and T2.
Figure 1. Station locations along the Kerala coast
The cross-shore and along-shore component of currents were higher at T1 (south) and
compared to T2 (north). The along-shore components of currents were high in surface layer
and decreased rapidly with depth at T1. The pronounced variations in cross-shore
component were absent. The along-shore component of current dominated than the crossshore component results a strong along-shore flow than the cross-shore flow.
As the prevailing winds were northerly or north-westerly, with the offshore transport
of surface water, the conditions were favorable for upwelling. The average speed at T1 and
T2 were 5.79 and 5.21 m s-1 respectively. The cross-shore wind stress (τx) was generally
greater than along-shore wind stress at T2; whereas the along-shore wind stress (τy) was
dominant at T1.
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SST was high (>30.94° C) in the offshore stations, but in coastal stations at 9° N, it was
lower (<30° C). Surface salinity was found to increase towards north than offshore (<35.1).
The prevalence of upwelling was evident in the vertical structures of temperature, salinity
and sigma-t. The up-sloping of isolines were more pronounced at the southern transect off
Kollam (Figure 3a). Shoaling of these signatures were absent in the northern transect off
Kannur. Upwelling as a result of equator-ward alongshore winds lower the SST, which
commences at the southern tip of India and propagates north-ward along the coast with the
advancement of monsoon (Rao et al., 2008).
(a) Off Kollam (9° N)
Figure 3. Hydrographic section of temperature, salinity and sigma-t.
References
Rao, A.D., Madhu Joshi and Ravichandran, M (2008), Oceanic upwelling and downwelling
process in waters off the west coast of India, Ocean Dynamics, 58: 213-226.
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PRELIMINARY OBSERVATIONS ON OCCURRENCE, SPATIAL DISTRIBUTION AND
IDENTIFICATION OF PLASTIC RESIN PELLETS IN SEDIMENTS AROUND AGATTI
ISLAND, LAKSHADWEEP ARCHIPELAGO
S. Veerasingam1*, M. Mugilarasan2, R. Venkatachalapathy2, P. Vethamony1
1
CSIR – National Institute of Oceanography, Dona Paula, Goa – 403 004, India; [email protected]
2
Faculty of Marine Sciences, Annamalai University, Parangipettai, Tamil Nadu – 608 502, India
Plastic resin pellets (0.1 to 0.5 cm in diameter) are transport medium for toxic
chemicals (including persistent organic pollutants and trace metals) in the marine
environment. Plastic resin pellets are worldwide persistent pollutants that accumulate in
ocean, especially on sandy beaches. However, their characteristics, accumulation zones,
and transport pathways remain poorly assessed. To improve the knowledge of occurrence,
spatial distribution and identification of plastic resin particles and their impact on coral reef
area of Lakshadweep Sea, a preliminary monitoring survey was carried out around Agatti
Island in November, 2014. For the quantification of plastic pellets along the inter-tidal
region, the 1 x 1 m quadrates were sampled in 20 locations around Agatti Island. The
collected pellets were air dried for 24 h to remove the moisture. Pellets were sorted out and
classified based on colour into three categories, namely, white, black and yellow. The dry
weights of individual plastic pellets were determined and recorded to the nearest 0.0001 g
on an electronic balance. The polymeric composition of each pellet was determined using
Fourier Transform Infrared Spectroscopy (Shimadzu FTIR spectroscopy). The transmission
FTIR spectra were recorded in the mid-infrared region (4000 – 400 cm-1).
The overall spatial distribution varied showed that higher occurrence of pellets was
found along the southwest part of Island. Significantly higher plastic litter accumulation was
found along the western part than eastern part of island. The white coloured pellets were
predominant with 75% by number of items and 66% by weight. The pellets on the beaches
were identified as polyethylene (PE), polypropylene (PP) and polyurethane (PU). In June,
2014 the Vietnam cargo ship ‘Viet Long’ was sunk off Summer Island, Maldives (southern
part of the study area). We suspect that this accident might have led to the plastic pellet
pollution of Agatti Island and other Lakshadweep Archipelago. Studies are required to
correlate marine debris accumulations with currents and shipping lanes to determine
sources of the plastic pellets, and to target clean up and prevention efforts. The effect of
plastic resin pellets on coral reefs, including toxicity of pellets and fragments that wash up
on the beaches throughout the Lakshadweep Archipelago, remains unknown, but should be
investigated.
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SEDIMENT TRANSPORT DURING NILAM CYCLONE AT KADALUR
PERIYAKUPPAM COAST, TAMIL NADU
A. S. Kiran*, B. K. Jena and K.M. Sivakholundu
Kadalur Periyakuppam (KPK) comprising of three fishing villages is located near
Kalpakkam in Tamil Nadu. These villages are surrounded by Palar River on the north and a
small creek on its south. The coastline of Kalpakkam is prone to erosion due to high wave
activities during monsoon and cyclones. Fish landing centers, belonging to Tamil Nadu
Government Fisheries department are under severe threat due to erosion. The erosion got
aggravated during Thane (2011) Nilam (2012) and Madi (2013) cyclones. National Institute
of Ocean Technology (NIOT) was approached by the Fisheries department to study the
coastal processes and suggest a suitable coastal protection measure.
NIOT has started various field studies, hydrographic surveys and Oceanographic data
collection from 2012 onwards. Monthly beach profile and shoreline variation is mapped by
using Realtime kinematic GPS (RTK-GPS) (Sivakholundu et al, 2014a). Hydrodynamic and
morphological modelling studies are carried out to understand the coastal processes based
on the in-situ data collected. Wave data is adopted from NIOT wave model/ NIOT wave
Atlas for the studies (Rajesh et al, 2009 & Sivakholundu et al, 2014b). Sediment transport
along the coast was studied using DELFT 3D model. The DELFT 3D results were analyzed
using DETRAN, a package developed by Deltares for estimating the cross-shore and alongshore sediment transport. As the major beach erosion occurs during cyclones as per field
data collection, a specific model study was carried out to understand the sediment transport
pattern during cyclones at KPK site. Nilam cyclone was selected for the study. In addition to
the data collected by NIOT, cyclone data is taken from Indian Meteorological Department
(IMD) and Joint Typhoon Warning Center (JTWC) websites.
The model results were compared with the actual beach loss measured using RTK-GPS
survey during the cyclone for validation. The actual beach loss during the cyclone for a
beach length of 300 m was 15000 m3 while the model results showed 13000 m3. The model
results show net and gross long shore transports during the cyclone as 0.09 x 106 m3 and
0.13 x 106 m3 respectively. The net and gross cross-shore transports during the cyclone are
0.06 x 106 m3 and 0.077 x 106 m3 respectively.
References:
Rajesh, P.R., Jossia, J.K. and Chaudhary, R.R. (2009). “Modeling of wave characteristics in
North Indian ocean”. Proc. of Int. Conf. in Ocean Engg., IIT Madras.
K.M. Sivakholundu., R. Vijaya., A.S. Kiran. and T. Abhishek. (2014a). “Short term
morphological evolution of sandy beach and possible mitigation: A case study off Kadalur
Periyakuppam”, Proceedings of Fifth Indian National conference on Harbor and Ocean
Engineering (INCHOE2014), 5-7 February 2014, CSIR-NIO, Goa.
K.M. Sivakholundu., Jossia, J.K. and Jena, B.K. (2014b). “Wave Atlas of the Indian
Coast”,ESSO-National Institute of Ocean Technology, Chennai.
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OPTIMIZATION OF ENTRANCE CHANNEL IN A TIDAL INLET FOR FISH LANDING
JETTY
L.R.Ranganath*, A.K.Singh, M.Karthikeyan and M.D.Kudale
Central Water and Power Research Station, Khadakwasla, Pune-411 024; [email protected]
There is a proposal for development of fish landing centre at Manjaguni, for providing
berthing facilities for fishing boats in Gangavalli River flowing entirely in the western
Karnataka into the Arabian Sea. As this proposed fish landing centre is located in the inlet
connecting to the open sea and sufficient landing space is available inside the inlet. Initially
two parallel breakwaters were proposed with a spacing of 160m to facilitate fishing boats to
enter the fish landing facility inside the estuary. The hydraulic model studies were carried
out to understand the tidal hydrodynamic behavior of flow, probable siltation pattern in the
fishing harbour and also helps in evolving layout of training walls/ groynes. The stretch of
shore region at the proposed site near Manjaguni is oriented in NNW-SSE direction. Semi
diurnal tide was observed in the site. The analysis of the current data indicated that there is
a reversal of flow during flood and ebb phase. The average value of suspended sediment
concentration is 0.01kg/m3 was considered in the model studies. The average D50 value of
the sediments was observed to be around 0.10 mm at site, which was considered for
simulation. MIKE21 mathematical model has been used to study the hydrodynamic
processes and to suggest a suitable layout including entrance channel. Further the
sedimentation pattern in the region was also studied using MIKE21 ST model. From
remotely sensed data of west coast it is found that Gangvalli river mouth has become
narrow as sediment accretion has increased on both the sides of river mouth, since spit has
shifted 70 m down south on the north and 105.2 m shift north up on the southern part of
the mouth (Richa Choudhary et al., 2013). From the hydrodynamic studies it can be
concluded that the parallel breakwaters with 140m opening and dredging the channel and
basin to -3m the current magnitude in the channel has increased facilitating natural flushing
of the channel to some extent. Sedimentation studies reveal that the maintenance dredging
tends to increase the basin area. The annual deposition of siltation is expected, and this
tendency of sediment deposition in the harbor basin needs to be tackled by maintenance
dredging. The frequency of maintenance dredging may be decided by regular monitoring of
the sedimentation pattern post construction of fish landing facility at Manjaguni Jetty.
References
Richa Choudhary, et al (2013), “Shoreline change detection from Karwar to Gokarna- South
West Coast of India using remotely Sensed data” Int. J. of Earth Sciences and Engineering.,
vol. 6, No. 03; June 2013, P. P. 489- 494.
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ROLE OF CURRENTS ON THE INTRUSION OF THE BAY OF BENGAL WATER
MASS TO SOUTHEASTERN ARABIAN SEA
Rajith, K., Rao, A. R. and Anil Kumar, K.
Naval Physical and Oceanographic Laboratory, Cochin 682021; [email protected]
Major current systems which are dynamically connecting the Bay of Bengal and the
Arabian Sea are the East India Coastal Current (EICC), the West India Coastal Current (WICC),
the Southwest (SMC) and the Northeast Monsoon currents (NMC). All these currents are
seasonally reversing with the seasonally reversing wind systems viz Southwest monsoon and
Northeast monsoon. These seasonally reversing currents play an important role in the
distribution of physical properties (temperature and salinity), chemical and biological
properties between the Arabian Sea and the Bay of Bengal. Another important feature
which has direct link with the current system is the intrusion of the Bay of Bengal Water in
to Southeastern Arabian Sea (SEAS). Earlier studies explains the dynamics and water mass
characteristics using modeling and satellite measurements and also from CTD data and
water quality analysis. However, the role of currents on the intrusion of Bay of Bengal water
mass based on in-situ measurement of currents is not addressed. Hence, detailed physical
oceanographic surveys were carried out in the SEAS from October 2013 to March 2014.
Spatial surveys on monthly basis were conducted along seven transects from 5°N to 11°N
(during October and from 8°N to 11°N in the subsequent months). Spatial data on
subsurface currents were collected using vessel mount ADCP. Along the transects, CTD data
were also collected with sample spacing of 30 NM. This paper depicts the salient physical
oceanographic features observed during the period of measurements. Observations reveal
favorable poleward current from the month of October onwards. During the first week of
November, low salinity waters observed in the eastern side of the transects. The
observations showed that, in the subsequent months, with the favourable poleward current
the low salinity water infringe up to 11°N. The study also reveals influence of the prevailing
eddy on current system. An attempt is also made to bring out the hydrodynamic processes
in the SEAS utilizing satellite data.
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CHANGING DEPOSITIONAL ENVIRONMENT ALONG NORTH MAHARASHTRA
COAST: REASONS AND POSSIBLE IMPLICATIONS
Volvoikar S. P1*, Nayak G. N2, Mazumdar A1, Peketi A1
1
CSIR- National Institute of Oceanography, Dona Paula, Goa – 403 004; [email protected]
2
2
Department of Marine Sciences, Goa University, Goa – 403 206
Mudflats and mangroves present along intertidal regions of estuaries and creeks are
known to favor deposition of fine grained sediments, associated metals and organic matter.
North Maharashtra along the west coast of India is one of the rapidly industrializing and
urbanizing regions. Large number of dams has been built and freshwater is being diverted
from rivers joining estuaries and creeks. The region has also experienced a change in
precipitation pattern over the past few years. Estimates of mean sea level rise along the
coast of India have indicated a rise of slightly less than 1mm/year. All these processes have a
potential to change the type and amount of sediment particles, metals and organic matter
deposited within the coastal and near-shore environments. Such changes are known to
affect the natural biogeochemical processes operating within the coastal regions. In the
present study therefore an attempt is made to understand the response of intertidal
sediments of north Maharashtra coast to these rapidly changing environmental conditions.
Sediment component (sand:silt:clay), total organic carbon (TOC), bulk sediment
chemistry (Fe, Mn, Al, Cu, Zn, Co, Ni and Pb), metal speciation, sedimentary stable isotope
(δ13Corg, δ15N) ratio and TOC /TN ratio analyses were carried out on intertidal core sediments
of estuary and creeks present along north Maharashtra coast. The results indicated a change
in hydrodynamic energy conditions from past to present all along the studied coastal region.
Organic matter proxies namely, TOC, δ13Corg and TOC/TN suggested significant decrease in
organic matter (terrestrial) input to Vaitarna estuary in recent years and is attributed to
decrease in freshwater influx. As a consequence of decrease in freshwater input, greater
amount of sea water seem to have intruded within the estuary as evident from the results.
In addition, δ15N results pointed towards anthropogenic input to Vaitarna estuary in recent
years from agricultural fields, domestic sewage and waste water. While metal concentration
and speciation in a creek present in near vicinity of an industrial zone has suggested drastic
increase in anthropogenic metal input in recent years. All such natural and anthropogenic
changes within relatively minor estuaries and creeks present along the west coast of India
therefore together may have a potential to significantly alter the natural biogeochemical
processes operating in the adjacent coastal Arabian Sea.
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DISTRIBUTION OF SUSPENDED PARTICULATE MATTER IN THE MANDOVI AND
ZUARI ESTUARIES: INFERENCES ON THE ESTUARINE TURBIDITY MAXIMA
Suja S , Pratima M. Kessarkar*, R. Shynu, V. Purnachandra Rao
CSIR-National Institute of Oceanography, Dona Paula, Goa 403004, India; [email protected]
The suspended particle volume concentration was studied along Mandovi and Zuari
(Ma-Zu) estuaries of Goa to decipher the spatial distribution of suspended particulate
matter (SPM). The SPM concentrations are lower in the Mandovi (2 to 1934 µl/l) than in
Zuari (3 to 3698 µl/l), whereas the grain size range (7- 370 µm) is similar in both estuaries.
The salinity values range between 0 to 34 and 0 to 35 in Mandovi and Zuari, respectively.
High concentrations of SPM occur at the river mouth in both estuaries and are associated
with high salinities (30 to 34) and restricted to top two meters. High SPM concentrations are
also observed at distance from mouth ~3.3 km in Mandovi and about 5.2 km in Zuari estuary
that extends vertically down to 8 m. These high SPM are associated with the salinity
gradient (30 to 4) that is observed up to ~ 18 km for Mandovi and 25 km for Zuari, beyond
this, salinity is< 4 and SPM is less than 100 µl/l. These two zones of high SPM are related to
the estuarine turbidity maximum (ETM) occurring at the same time. The first ETM at sea end
of the estuary is associated with high salinity, and is due to resuspension of particles due to
wind-induced and tidal currents, whereas the second ETM at upstream is associated with
salinity gradient and due to flocculation and coagulation and settling of SPM.
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IMPACT OF THE VERY SEVERE CYCLONIC STORMS – THE PHAILIN AND
HUDHUD – ON THE BEACH PROCESSES ALONG THE VISAKHAPATNAM COAST
Hani, T.*, Ganesan, P. and Murty, V.S.N.
CSIR – National Institute of Oceanography, Regional centre, Visakhapatnam – 530 017; [email protected]
Beaches offer an extremely interesting phenomenon with their continuous dynamic
changes, but maintaining equilibrium through accretion and/or erosion of sand along the
beach. On the east coast of India, the processes of sand deposition and erosion on the
beach exhibit seasonal changes and cause beach morphological variations. In order to assess
the beach morphological changes along the Visakhapatnam coast over a longer period,
weekly beach profiling is being carried out at 5 locations along the Visakhapatnam beach
between Rishikonda and Fishing Harbour. This study analyses the weekly profiling over a
period of 43 months beginning from May 2011 to December 2014. In this period, the
Visakhapatnam beaches experienced the impact of two Very Severe Cyclonic Storms
namely, the Phailin in October 2013 and Hudhud in October 2014. This study also aims at to
identify the possible safety locations along the beach to minimize the drowning death cases.
The rates of erosion and deposition at each location are estimated and compared. It is
found that the beaches at the 5 locations underwent appreciable rates of
erosion/deposition during the study period. Maximum (~45 cu.m) sand erosion occurred at
North of the Submarine (Station 3) in January 2013. All 5 stations underwent severe erosion
during southwest (SW) monsoon and deposition during winter monsoon and maintain
beach equilibrium during pre-monsoon period. It is found that this normal trend is reversed
at North of the Submarine (Station 3), wherein the beach is more stable during SW
monsoon period, and more vulnerable for erosion in winter and pre-monsoon period. The
Rishikonda beach appears to be safe place throughout the year. During the ‘HUDHUD’
cyclone in October 2014, the beach erosion effect was very severe, and a net volume of
sand of about 1457 cu.m was lost over a beach stretch of 14 km. Weekly waterfront
changes were large up to ±35 m at each location during the study period. Seawater
advanced by 35 m onto the beach and up to the beach road at most of the places during
“HUDHUD’’ cyclone. A good correlation (r=0.6) between weekly waterfront changes and
weekly sand volume changes occurs at the north of Submarine beach and Fishing harbour
beach and a negative relationship with a poor correlation is noticed at the Ramakrishna
beach, where severe erosion occurred during both Phailin and Hudhud cyclones. However,
drowning death cases in the beach waters are reduced greatly, partly due to improved
public awareness by the local government authorities.
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SEASONAL AND INTER-ANNUAL VARIABILITY OF COASTAL CURRENTS AND
CIRCULATION OFF VISAKHAPATNAM DURING 2010-2014
V.S.N.Murty1, D.Gayatri Vani1*, Y.Steeven Paul1, V.Fernando2, T.A.Prakash2, Almeida
Anselmo2 and A.Suryanarayana2
1
CSIR-National Institute of Oceanography, Regional Centre, Visakhapatnam – 530017; [email protected]
2
CSIR-National Institute of Oceanography, Dona Paula, Goa – 403004
Analysis of the Acoustic Doppler Current Profiler (ADCP) measured time-series
currents data at a shallow (~100 m depth) and a deep (~1000 m depth) station off
Visakhapatnam during May 2010-February 2014 is presented. The currents data in the
water column (20 – 100 m & 45-355 m) and water temperature at the depth of ADCP (100 m
and 400 m) were acquired at time-intervals between 15 minutes and 1 hour. The time-series
of zonal (u) and meridional (v) currents were 36 hour low-pass filtered and daily averaged.
This filtered data is used to examine the low-frequency variability in the currents and depth
integrated volume transports off Visakhapatnam. Fast Fourier Transformation (FFT) spectral
analysis is carried out to identify the dominant spectral peaks (above 95% confidence
interval) in the observed coastal currents.
The analysis reveals the presence of sub-seasonal, seasonal and inter-annual
variability in the coastal currents off Visakhapatnam. Higher spectral density peaks occurred
at 8-10 day and 50-100 day periods in zonal currents and at 7-8 day and 33-80 day periods in
meridional currents. Observed currents attained high magnitudes (120 cm/s) in April, when
the seasonal East India Coastal Current (EICC) flowed northward during January – April. EICC
flow reversal occurred during October – November. During Southwest monsoon period, the
coastal current is directed towards southwest, as part of the cyclonic eddy off
Visakhapatnam. The annual variation of monthly mean zonal and meridional volume
transports show northeastward transport of 4-6 Sv (1 Sv = 106 m3/s) during February – April,
and southwestward transport of similar magnitude from mid-July to October. The transports
in 2010 and 2011 exhibited large variability in accordance with the anomalous wind field
and coastal circulation in association with the negative and positive Indian Ocean Dipole
(IOD) events in these years. Large interannual variability is noticed in the volume transports
of coastal currents during 2010-2013.
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ROLE OF LITHOLOGY AND STRUCTURE ON THE COASTAL LANDFORMS OF
GOA, INDIA
G. Q. Fernandes1*, S. D. Iyer2, K. Mahender 3
1
Don Bosco College of Engineering, Fatorda, Goa; [email protected]
2
CSIR-National Institute of Oceanography, Dona Paula, Goa
3
Goa University, Taleigao, Goa
The Indian Plate together with Madagascar rifted from East Africa during Late Jurassic
(150 Ma) and subsequently in Late Cretaceous the Indian Plate separated from Madagascar
(Chatterjee S., Scotese C., 1999). This breakup of the Indian Plate from the Gondwana
resulted in the present coastline of western India and was subsequently shaped by oceanic
processes.
Goa (area 3700 sq km) has three broad physiographic divisions: a wide coastal plain,
an undulating midland hilly region and the western ghat. The coastal plain is 105 km long
and comprised of pocket and straight beaches, dunes, estuaries, wave cut platforms and
headlands amongst others.
We studied the rocks exposed along the coast of North Goa (Arambol, Morjim,
Chapora, Baga, Aguada and Mormugao) to examine the geological structures and coastal
processes. The lithology is mainly metagreywackes of the Goa Group, Dharwar Supergroup,
and best exposed as sea cliffs, headlands and wave cut platforms. There are intrusions of
dolerite dykes contemporaneous to Deccan Trap time. At several places occur laterite
cappings and tablelands.
The metagreywackes have a strike of NE-SW and an average dip of 30°. Various
sedimentary depositional features like laminations, tabular cross bedding and ripple marks
are seen. Graded bedding and Bouma sequence are distinct and indicate deposition from
turbidity currents (Bouma, A. H., 1962). Warping is observed in the laminations, which are
formed due to the crustal adjustments of the stresses. This is demarcated by massive
bedding with graded bedding followed by parallel laminations and with convolute bedding.
Liesegang rings occur across the bedding plane, which are arranged in a regular repeating
pattern.
The area has been subjected to various geological processes (deformation, erosion,
deposition, and diagenesis) from the time the coastline formed to the present time. The
depositional stage was followed by intrusive events, which led to the emplacement of dykes
of two generations, showing cross cutting relations along with quartz vein intrusions. This
intrusive phase was followed by deformation phase leading to folding, faulting and
brecciation. Small scale folding is seen locally. An anticlinal fold is delineated at Vagator with
a limb dipping due north and the other due south. Micro-faulting is seen in
metagreywackes. A sheared zone is present in metagreywacke along with the quartz veins,
which are brecciated and mylonitised. Finally, the coastal wave action led to the erosional
structures, which are seen as box work and scour marks. In the present environment, the
sediment substrate is subjected to scouring current action and is eroded.
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In contrast to the above, South Goa has long sandy beaches with a paucity of
headlands. Further South at Canacona, gneiss and granites form hillocks and cliffs that are
intruded by mafic dykes.
In summary, the variable coastal landforms at North and South Goa have resulted due
to interaction of the different lithology and structure with the coastal processes. The
coastline is been categorized by Fernandes (2009), as submerged and emergent coast. The
shorelines with dominant sandy beaches are formed by active deposition, characterizing
these as an emerged coast. Whereas, the prominent outcrops as cliffs, headland and rocky
terrain were formed due to the continuous wave action and are typical of a submerged
coast.
References:
Davidson, M. A., T. J. O’Hare, and K. J. George (2009), Tidal modulation of incident wave
heights: Fact or Fiction?, Reef Journal, 1(1), 16-32.
Leatherman, S. (ed.), Barrier Islands, from the Gulf of St. Lawrence to the Gulf of Mexico,
Academic, New York.
Thuy, V. T. T. (2013), Aspects of Inlet Geometry and Dynamics, The University of
Queensland, Brisbane, Australia.
Zijlema, M., G. Stelling, and P. Smit (2011), SWASH: An operational public domain code for
simulating wave fields and rapidly varied flows in coastal waters, Coastal Engineering,
58(10), 992-1012.
Bouma, A. H. (1962), Sedimentology of Some Flysch Deposits, Elsevier, Amsterdam.
Chatterjee S., Scotese C. (1999), The breakup of Gondwana and the evolution and
biogeography of the India plate. In: Proceedings of the India National Science Academy. Vol
65, No. 3, pp 397-425.
Fernandes O. A. (2009), The evolving coast of Goa: a geological perspective. In: Natural
resources of Goa: A geological perspective. Geol. Soc. Goa. pp 25-34.
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INTERNAL TIDES ON THE CONTINENTAL SHELF AND SLOPE OFF THE EAST
COAST OF INDIA
A.K. Jithin*, A.S. Unnikrishnan, Fernando Vijayan, M.P. Subeesh, R. Fernandes, S. Khalap, S.
Narayan, Y. Agarvadekar, M. Gaonkar, P. Tari, A. Kankonkar, S. Vernekar
CSIR-National Institute of Oceanography, Dona Paula, Goa, 403004; [email protected]
Internal tides are internal waves at tidal frequencies, generated by the interaction of
barotropic tide with the topographic features like continental shelf, slope and ridges in a
stratified ocean. Time series observations obtained from moored Acoustic Doppler Current
Profilers (ADCP) deployed on the shelf and slope off Gopalpur (19.4°N), Kakinada (16.3°N),
Ramayapattanam (15°N) and Cuddalore (12.01°N) during 2009 - 2011, were used to study
the spatial and temporal variability of both barotropic and internal tides along east coast
India. Magnitude of barotropic tidal currents varies from 2.4 to 9.9 cm/s from southern to
northern part of the shelf. Harmonic analysis showed that semidiurnal tidal current is
dominant at all locations with M2 and S2 tidal components having magnitudes of 1.7 to 3.6
cm/s and 1.0 to 1.8 cm/s respectively. Diurnal tidal components are found to be relatively
small at all locations. Barotropic tidal current increases from southern to northern part of
the shelf. Barotropic tidal current ellipses are oriented perpendicular to the isobaths at
Cuddalore and Ramayapattanam, while at Kakinada, they are parallel to the isobaths. At
Gopalpur, barotropic currents have comparable magnitude in both parallel and
perpendicular directions. Spectral Analysis of baroclinic tidal currents showed large peaks at
semidiurnal frequencies in all locations. EOF analysis describes structure of internal tides,
where they are dominated by first mode. However, higher modes are also found to be
essential to describe the variability. Temporal variability associated with vertical structure
and amplitude of internal tides are expected because of the seasonal changes occurred in
stratification. Internal tides do not show spring - neap cycles but occasional intensification is
evident from the time series observations. Computed variance in different vertical levels
shows that bottom amplification of the internal tide is a characteristic feature of internal
tides on the shelf. We computed criticality of the slope region for the generation of internal
tides using available data on hydrography and bathymetry and found that continental shelf
and slope regions are critical for the generation of semidiurnal internal tides.
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NEARSHORE PROCESSES AND LITTORAL SEDIMENT TRANSPORT AT AN OPEN
BEACH ALONG THE NORTH TAMIL NADU COAST
D. Sathish Kumar1, Basanta Kumar Jena1*, Usha Natesan2 and K.M.Sivakholundu1
1
National Institute of Ocean Technology, Chennai, 600100; *[email protected]
2
Centre for Water Resources, Anna University, Chennai, 600025
Littoral sediment transport plays a major role in understanding the nearshore and
beach system. A study has been carried out to examine the site specific nearshore processes
through a detailed field observation. Variations in the littoral environmental characteristics
had been measured daily for a period of one year at three locations with an interval of
about 1 km at Kadalore Periyakuppam. The daily and seasonal variations in nearshore
breaker characteristics and longshore sediment transport rate are studied. The field
observation has been supplemented by Simulating Waves Nearshore (SWAN) model using
the Wave atlas information (NIOT, 2014). The breaker height during post monsoon, premonsoon and monsoon season are from 0.8 to 1.5 m, 0.4 to 0.8m and 0.6 to 1.0m
respectively. Wave period ranges from 5 to 8 sec. Longshore currents are higher during
monsoon from 0.2 to 1 m/s whereas during post monsoon and pre monsoon it was 0.3 to
0.7 m/s and 0.1 to 0.4 m/s respectively. The estimated annual net longshore sediment
transport rate (LSTR) for the region is 0.4x106 m3/year and 0.1 x106 m3/year based on CERC
and Kamphuis formula respectively. Monthly and seasonal variations in LSTR are primarily
influenced by breaking wave height and direction. The comparison between the LSTR
calculated using simulated wave at 2 meter contour shows a good agreement with the
measured Littoral Environmental Observation. The net LSTR estimated from waves
simulated using SWAN are 0.32 x106 m3/year and 0.06 x106 m3/year respectively using CERC
and Kamphuis formula. The CERC formula shows a 300 percent higher estimate on LSTR
compared to that of Khamphuis for the study area. This variation is largely attributed to the
dependence of breaking wave type which is considered in Khamphuis formula. Hence the
LSTR estimate based on Khamphuis formula can be considered reliable for the study area.
Estimation of Longshore sediment transport rate using recently developed models will be
explored to identify the most suitable method for longshore sediment transport rate
assessment.
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HYDRODYNAMIC AND WATER QUALITY SIMULATION OF SEWAGE
DISCHARGES IN WEST COAST, MUMBAI: PRESENT AND FUTURE SCENARIO
Trupti Mardikar, Ritesh Vijay* and Satish R. Wate
CSIR-National Environmental Engineering Research Institute, Nagpur, Maharashtra; [email protected]
Mumbai, one of the most populated cosmopolises in the world, is a coastal city with
Arabian Sea on the west and Thane Creek on the east. The city generates huge quantity of
sewage which is discharged into drains, nallahs, creeks and coastal water after preliminary
and primary treatment. Though coastal waters have an extensive assimilation capacity, its
quality deteriorates due to this mixing. As sewage is principally organic, it experiences
bacterial decay. This bacterial decomposition reduces the dissolved oxygen (DO)
concentration in water, thus increasing the biochemical oxygen demand (BOD) of the water.
This poses a severe threat to the coastal environment and its alleviation is a serious
concern. Researchers have regularly utilised numerical models for water quality assessment
and management of coastal water bodies. These models help in interpretation of
environmental processes, predicting pollution impacts, and evaluating the future trends in
environmental quality. The objective of the present study is to assess the impact of sewage
discharges on water quality of west coast, Mumbai using MIKE 21 hydrodynamic and water
quality simulation. The water quality in terms of BOD, DO and Faecal Coliform (FC) is
assessed for the present condition (2014) as well as predicted scenario of 2025, based on
the SW-II standards. A model is conceptualized based on bathymetry, tide and current,
coastal water quality, sewage discharges from drains, nallahs, wastewater treatment
facilities, and ocean outfalls. The simulation is validated by comparing the hydrodynamic
and water quality findings with the in situ observations. The validated model is used in
prediction of water quality scenario of 2025 for stipulations like improvement in wastewater
collection, appropriate treatment level and disposal of treated effluent from existing and a
proposed outfall at Erangal. The simulation results show that the existing water quality of
west coast does not comply with standards but improves significantly in the future scenario
for above mentioned conditions. The simulation study underlines the need of better
planning and management of existing coastal environment and exploring options like reuse
and recycle of treated effluents instead of discharging huge quantities in coast as an effort
for water conservation.
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IDENTIFICATION OF INLET AND OUTLET FOR COOL SEAWATER DISCHARGE
FROM AN LNG FACILITY: A SIMULATION APPROACH
Vikash K. Kushwaha, Ankit Gupta, Ritesh Vijay* and Satish R. Wate
CSIR-National Environmental Engineering Research Institute, Nagpur, Maharashtra; [email protected]
A simulation study has been carried out to assess the impact of cool seawater
discharges from a Liquefied Natural Gas (LNG) facility in the coastal environment using MIKE
21. The research study entails Hydrodynamics (HD) and Advection Dispersion (AD)
simulations to assess the dispersion of the seawater discharge from Open Rack Vaporiser
(ORV) outlet of proposed LNG terminal in the vicinity of the Gulf of Kutch, India. The
modelling system was based on the numerical solution of the 2D incompressible Reynolds
Averaged Navier-Stokes equations subject to the assumptions of Boussinesq and hydrostatic
pressure. The model conceptualisation consists of equation of mass balance, momentum
balance along with transport equation for temperature and salinity. Hydrographic boundary
conditions in terms of tidal variations (in time and space) and flux boundary at the open
model boundary were defined. The available secondary tidal and current data within the
model domain were used for model calibration and validation. The present condition of HD
was calibrated and validated by comparing the observed and simulated hydrodynamics in
terms of water depths, current speeds and directions within the model domain. The model
was significantly correlated with coefficients 0.98, 0.86 and 0.91 for water depth, current
speed and direction, respectively. The validated model was extended to predict the AD
phenomena under different design scenarios based on positions of inlet and outlet and their
discharge rates and temperatures. AD boundary conditions were specified in terms of
constant ambient seawater temperature at the model boundaries. These scenarios were
formulated in view to minimise the potential impact of cool seawater discharge and to
select an environmentally benign and energy efficient option for such cool seawater
discharges. The predicted simulation results of cool water discharges were assessed to
comply with the existing Environmental Health and Safety, World Bank guidelines for LNG
discharge facilities. The key factors which affected the recirculation of cool seawater
discharges were identified as the location of inlet and outlet, distance between the inlet and
outlet, the spreading behaviour of the cool water from the outlet, the tidal action and the
wind stress and its direction. The results suggest that a trade-off is required before taking
engineering decisions for selecting an environmentally acceptable and energy efficient
option with respect to pumping power and operational efficiencies for such cool water
discharges from an LNG facility. An optimum inlet-outlet location along with best possible
flow rates and temperature difference between the inlet-outlet is identified and
recommended. As there are no standards for cool seawater discharges from an LNG facility
at national and international level, research findings of this paper will encourage policy
makers to formulate coherent standards for such cool seawater discharges into marine
coastal environment.
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VARIABILITY OF INTERNAL TIDES ON THE CONTINENTAL SLOPE OFF JAIGARH,
WEST COAST OF INDIA
M.P Subeesh*, A.S Unnikrishnan
CSIR-National Institute of Oceanography, Dona Paula, Goa, India, 403004; [email protected]
A number of long term ADCPs were deployed along the slope and shelf off west and
east coast of India by CSIR-National Institute of Oceanography. They were utilized to study
the low and high frequency currents in recent years. In an earlier work, we analyzed the
ADCPs deployed on the shelf and the characteristic features of internal tides were
discussed. In the present work, we report a detailed study of internal tides on the slope off
Jaigarh using the ADCP measurements, made in March-October 2008. The observation
period comprised of the pre-monsoon (March-April) and SW (South-West) monsoon (MaySeptember) seasons. We focus temporal, seasonal and spatial variation of internal tide in
detail. We observe significant internal tides, exceeding 20-25 cm/s during the spring time,
which appears to be modulated strongly by local barotropic tidal currents. The internal tide
spectral level in the tidal frequencies are elevated above the GM reference spectra.
Baroclinic current spectra are dominant in internal tidal frequencies M2, S2, K1 and O1, with
stronger signals found in semi-diurnal frequencies compared to diurnal frequencies. A large
fraction of cross-slope and along-slope internal tides are phase-locked with the astronomical
tides shows the stability of internal tides. EOF analysis shows that about 65% of variance of
internal tidal currents are associated with first mode where the upper water column flows in
one direction and the lower water column in opposite direction with 180° phase shift. The
second and third EOF modes contain 10 and 4% of variance respectively. EOF spatial
structure are consistent with the dynamic normal modes. We studied the possible causes of
strong internal tides on the slope by determining Baines barotropic body forcing and
criticality around the region. It is found that the shelf-edge and slope regions off Jaigarh are
favorable for the generation of internal tides. Finally we investigated the seasonality of
internal tides on the slope. On the slope internal tides are found to be strong during premonsoon and comparatively weak in SW monsoon. Further analysis demonstrates that M2
exhibits strong seasonal variation than other constituents.
During pre-monsoon the
incoherent internal tides in M2 is found to be contributing a large fraction of total internal
tide. Some part of the M2 internal tide here could be coming from elsewhere.
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A CASE STUDY OF SST DISTRIBUTION OVER BAY OF BENGAL DURING
HUDHUD CYCLONE
T.S.D.Bhavani*, G.Bharathi, P.Amarendra and P. Hariprasad
Andhra University, Visakhapatnam; [email protected]
Tropical cyclone HUDHUD which developed in the Bay of Bengal during 07th October 14th October 2014. The system crossed off Visakhapatnam coast on 12th October 2014.
Temperatures greater than 30oC over most of the bay were present from 05th October
2014. A significant change in the spatial structure in sea surface temperature was observed
on 12th October 2014 with a temperature minimum at (16°N, 86°E) and sharp temperature
gradients around this area. The cold temperatures are well developed at the time when the
centre of the storm is located near 86oE and 16oN. A Sea Surface Temperature decrease of
about 4.2oC is apparent to the right of the storm track and areal extent of minimum
temperatures is about 1.0o X 1.4o degrees. The maximum sea surface cooling observed after
the passage of Tropical Cyclone is 30.5oC. The maximum cooling was observed on 12-102014. The cooling of the sea surface persists for about more than a week and is readily
detected in satellite images. The recovery of the ocean to the cyclone passage is within
seven days.
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THE ROLE OF WAVE CLIMATE ON COASTAL SEDIMENTATION - A CASE STUDY
R. Anjali1, K.Jossia Joseph2*, B. K. Jena2, K.M. Sivakholundu2 and Ravibabu Mandla3
1
VIT University, Vellore
2
Coastal areas are experiencing a continuous change in the geomorphological system.
It is observed that certain areas along the east coast of India are experiencing severe
erosion. The severity of erosion increased in the recent past posing threat to life and
property in the coastal areas. This necessitates the detailed study of various processes
affecting coastal sedimentation. The present study aims to find the impact of wave climate
on the coastal sediment transport and change in coastline at two selected locations viz.:
Cuddalore and Kadalur Periyakuppam, Tamil Nadu in east coast of India.
NIOT has prepared a Wave Atlas of the Indian Coast using 15 year simulated wave
data (Sivakholundu et. al., 2014). The wind and wave data are extracted from the database
for the period 1998 to 2012 at the above selected locations. The long term average of
monthly, annual and seasonal wave parameters are analyzed to identify the causative effect
on coastal sedimentation. LITPACK model is used to compute littoral drift and coastline
evolution.
The long term average of Significant Wave Height (SWH) exhibits calm wave
conditions with an average of 0.73m, 0.67m at Kadalur Periyakuppam and Cuddalore
respectively. The annual average SWH exhibits an increasing trend, which increased from
0.69m in 1998 to 0.82m in 2012 at Kadalur Periyakuppam and 0.64m in 1998 to 0.74m in
2012 at Cuddalore. The maximum SWH of 0.83m (Kadalur Periyakuppam) and 0.76m
(Cuddalore) are observed in the year 2011 attributed to the passage of thane cyclone near
these locations. The long term average of monthly and seasonal values of SWH exhibits the
similar trend at both locations with higher values at Kadalur Periyakuppam. The SWH
exhibits lowest values during June to September followed by an increasing trend with
maximum values in December. Higher wave activity coincides with North-Northeasterly
waves whereas the low SWH is observed during south-southwesterly waves. Preliminary
results of LITPACK model indicates higher erosion at Kadalur Periyakuppam compared to
that of Cuddalore.
References:
Sivakhoulundu, K.M., K. Jossia Joseph and B. K. Jena, (2014), Wave Atlas of the Indian Coast,
ESSO-NIOT, ISBN: 81-901338-4-5.
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22-24 March 2015
IMPACT OF CYCLONE ON THE COASTAL AREA THROUGH EMPIRICAL
RELATIONS AND NUMERICAL MODEL
P. Vyshnavi1, B. K. Jena2*, K. Jossia Joseph2, J. Rajkumar2 and Ravibabu Mandla1
1
VIT University, Vellore
Coastal and Environmental Engineering, National Institute of Ocean Technology, Chennai; [email protected]
2
The passage of a tropical cyclone accompanied with strong waves, extreme wind and
torrential rain causes severe damage to life and property in the coastal area. The extreme
weather conditions make it difficult to measure the impact and moreover necessitate
estimation of cyclone impact through empirical relations and numerical modelling. The
estimated values can provide a preliminary assessment of the cyclone impact along the
coastal stretch.
The recent cyclone HUDHUD (October 2014) which made landfall in Visakhapatnam is
selected for the present study. The cyclone track data from India Meteorological
Department (IMD) for the period (1960-2014) is utilised to estimate the cyclone frequency,
cyclone induced wave height, storm surge and wave power. MIKE21 Spectral Wave model is
used to quantify the wave parameters during cyclone passage. The estimated values using
empirical relations are compared with model results and are validated using directional
wave rider buoy data off Visakhapatnam.
During cyclone HUDHUD, the maximum significant wave height (SWH) estimated
through empirical relation is 9.31m for the highest intensity of cyclone (12 October 2014 at
6:00 hrs near Visakhapatnam at 83.4 E, 17.6 N), whereas the model result is 10.49m. The
wave power estimated to be 602.24kW, while model result exhibits 706.4kW. Maximum
storm surge of 1.40 meters above the astronomical tide has been reported by the tide
gauge at Visakhapatnam (IMD report October 2014), whereas the estimated surge height is
1.59m. The maximum SWH observed at buoy location (12 October 2014 at 8:33 hrs near
Visakhapatnam at 83.27 E, 17.63 N) is 8.1m, whereas that of model is 8.4m. The wave
power computed using measured data is 438.58 kW and model result is 416.54 kW at the
buoy location. The result exhibits good agreement between measured, estimated and
simulated results for SWH and wave power. The estimated storm surge agrees well with the
measured value.
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AN OBSERVATIONAL STUDY ON WAVE CHARACTERISTICS DURING HUDHUD
CYCLONE OFF GANGAVARAM
P. Amarendra1,2*, K.Gopala Reddy2, G. Bharathi1, P. Bhanumurthy2 and T.M. Balakrishnan
Nair3
1
Center for Studies on Bay of Bengal, Andhra University, Visakhapatnam; [email protected]
2
Department of Meteorology and Oceanography, Andhra University, Visakhapatnam
3
Wave characteristics were studied using buoy observations made at half hourly
intervals during recent HUDHUD cyclone. This cyclone had shown strong impact on Coastal
areas of Andhra Pradesh were severely damaged by the strong winds in East Godavari,
Visakhapatnam and Vijayanagaram districts, winds were reached up to 180kmph as
reported by Indian Meteorological Department. System moved very slowly at the rate of
15kmph. From buoy observations, off Visakhapatnam maximum significant wave height
observed is 8.1m.
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TIDAL STREAM ENERGY POTENTIAL AT MANDOVI AND ZUARI RIVERS, GOA
Jaya Kumar Seelam1, Manasa Ranjan Behera2, R. Mani Murali1, Aqleema Shah2, D.
Ilangovan1, P. Mehra1, R. Madhan1
1
2
Indian Institute of Technology Bombay, Mumbai
The depleting natural fossil fuel deposits and increasing fuel consumption has
necessitated a search for sustainable and renewable energy sources. Extraction of energy
from oceans is an emerging source of national interest. There have been successful
attempts in extracting tidal energy by construction of barrages, impounding of water and
utilizing the potential energy or installation of underwater turbines, exploiting the kinetic
energy of the flow (Bedard et al., 2005)
In India, high tidal range locations are in the Gulf of Kuchchh, Gulf of Khambhat, and in
Sunderbans. The tidal energy potential assessed from these locations is about 8300MW
(Ministry of New and Renewable Energy - Tidal Energy., 2013). It is assumed that these
potential magnitudes are based on the method of impoundment through barrages.
However, detailed studies based on tidal stream potential for the high tidal range sites in
India have not been carried out yet.
The study of tidal flow in the Gulf of Khambhat is an endeavour to assess the potential
kinetic tidal energy that can be extracted in the Gulf of Khambhat (Aqleema., 2014). Apart
from the macro-tidal range locations, tidal inlets with meso-tidal range regions also have
tidal stream energy potential which has not been hitherto assessed, which has been focused
in this paper. Study has been carried out for two major rivers of Goa, viz., the Zuari River
and the Mandovi River. Numerical model studies were carried out to simulate the flow
patterns along these two rivers for a period of 15 days to estimate the tidal current speeds
across the study area (shown in Fig.1). MIKE by DHI hydrodynamic numerical software suite
capable to simulate physical coastal processes has been used for numerical modelling. Tidal
current speeds along the two rivers were obtained over the entire estuarine region and
analysed for the statistical mean and maximum flow speeds. Salient locations (M1, D1, Z1)
have been chosen, each along the Zuari and Mandovi estuaries, where maximum flow
speeds were observed, for further analysis of the tidal stream energy potential estimation.
The maximum tidal current speed is found to be of the order of 1.5 m/s (Fig.2). The
recent tidal turbines can extract power from current speed less than 1 m/s. It can also be
observed that the tidal current speed is sufficient to harness power for some period in one
spring neap cycle.
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M1
Mandovi R.
D1
Zuari R.
Z1
(a)
(b)
Fig. 1 (a) Computational domain considered for present study (b) Estuaries of Zuari and
Mandovi
Fig. 2 (a) Typical tidal profile off Goa (b) Velocity profile at locations (M1, Z1 and D1)
References:
Aqleema, S. (2014). Assesment of tidal Kinetic Energy of Gulf of Khambhat.
Bedard. (2005). Survey and Characterization Tidal In Stream Energy Conversion ( TISEC )
Devices (pp. 1–185).
Ministry of New and Renewable Energy - Tidal Energy. (2013). http://www.mnre.gov.in/
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OBSERVED TEMPORAL AND SPATIAL VARIATION OF STRATIFICATION IN THE
ZUARI ESTUARY, WEST COAST OF INDIA
D. Sundar1, A.S. Unnikrishnan, G.S. Michael, A. Kankonkar
CSIR-National Institute of Oceanography, Dona Paula, Goa, 403004, India; [email protected]
To study the temporal and spatial variability of stratification in the Zuari estuary, time
series measurements of vertical salinity profiles and currents were conducted over a tidal
cycle of 25 hours, during spring and neap tidal cycles and pre-monsoon, monsoon and post
monsoon seasons in 2011, at four stations in Zuari estuary located in Bay, in Lower middle
estuary, in Upper middle estuary and in Upstream regions. Astronomical tides were
predicted at these locations to examine the stratification variability with tidal phase. Mixed
tide with semidiurnal dominance is seen in this region. It is observed that stratification at
Higher Low water succeeding Lower High water is more intense than that of Lower Low
water succeeding Higher High water over a tidal cycle, in the mixed tidal regime with
semidiurnal dominance. During monsoon in lower middle estuary, salinity value peaks from
fresh water condition of zero to about 10 during neap and 14 during spring at high waters,
which seemed similar to the pre-monsoonal conditions at the upstream station. During premonsoon at upstream station also, only during the high waters the salinity value peaks from
zero to about one. This peaking of stratification at Lower middle estuary during monsoon is
found to weaken slightly by about 3 to 4 units at the peak of the high waters, during both
spring and neap tidal phases. The incursion of high saline downstream water at Lower
middle estuary causes saturation of salinity of near bottom waters for about 3 to 4 hours at
about the peak of high water, while surface salinity continues to increase to reach a peak
value to fall after high water with the ebb flow. The combined effect of salinity saturation of
bottom water and continuous rise and fall in salinity value of surface water, causes the
weakening of stratification at high water. The mean salinity over a tidal cycle was calculated
for all observations. Only in upper middle estuary during post monsoon, the mean tidal
salinity during spring tidal phase was lower than neap phase value. This is unique as during
other observations, the mean tidal salinity value is always higher during spring than at neap.
Larger tidal excursion of estuarine water during spring tidal phase, leads to advection of
very low saline water of post monsoon from quite far regions of upstream to upper middle
estuary, causing low mean tidal salinity value.
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EFFECT OF CLIMATE CHANGE ON ESTIMATION OF DESIGN WAVE HEIGHT
V. R. Remsiya and Manasa Ranjan Behera
Indian Institute of Technology Bombay, Mumbai; [email protected]
Design of coastal and offshore structures require proper estimation of design wave
height that plays a crucial role in their serviceability and durability. Traditionally, all the
marine structures were designed on the basis of available historic data. However, in view of
the scenario of potential climate change and global warming (Fig.1), the frequency of
extreme wind occurrences as well as regular wind speeds has increased significantly (IPCC
2013). Thus, the wind generated waves are expected to take shape according to the
variation in the wind speed and possibly with higher magnitude and frequency. However, it
is necessary to quantify the variation in the wave characteristics based on forecasted wind
speed data for the changing climate scenarios. In this study, an attempt has been made to
establish a relation between the wind speed and wave characteristics in the Arabian Sea for
the past events using artificial neural network (ANN), which could help in assessing the
future wave climate based on the projected wind speed.
A region along the west coast of India (shown in Fig.2) was considered for this study,
where 9 locations were selected to carry out the data analysis. Re-analysis wind and wave
height data from ECMWF for past 30years were obtained. The long term design significant
wave heights with a return period of 100 years were obtained from the daily mean
significant wave height data. Predominant wind directions were also obtained for the
selected locations by analysing daily mean wind speed for the same period. An ANN model
was developed using the past data for each location. Feed forward back propagation
network architecture was used with three different types of layers connected to each other.
The training function used was TRAINLM and adaption learning function was LEARNGDM.
The correlation coefficient obtained from the ANN model shows robust performance of the
neural network. Similarly, ANN model was developed for the off Bombay location (18.595°N,
71.031°E) where the wind speed and significant wave height data from the NDBP moored
buoy is available for the time period 1998-2000. The ANN model results using ECMWF data
were compared with the moored buoy records for significant wave height and found to be
in reasonably good agreement.
The third generation global climatic model wind data will be collected for a period of
30 years (2016-2045) and will be used for obtaining the future wave heights at all 9
locations using the respective neural networks. The design significant wave height for a
return period of 100 years will be calculated from the estimated daily mean significant wave
height data for the future 30 years. Thus, the effect of changing climate on the design
significant wave height can be substantiated.
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Fig. 1 Observed globally averaged combined land and ocean surface temperature anomaly for
1850-2012 (IPCC 2013)
Fig. 2 Study region along west coast of India and the salient locations considered (Image used
from Google Earth)
References
Deo M. C. and Naidu C S (1999), “Real time wave forecasting using neural networks”, Ocean
Engineering, 26, 191-203.
Mandal S, Prabaharan N (2006), “Ocean wave forecasting using recurrent neural networks”,
Ocean Engineering , 33, 1401–1410.
Radhika S, Deo M. C. and Latha G. (2013), “Evaluation of the design wave height used in the
design of offshore structures considering the effect of climate change”, Proceedings of the
Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime
Environment, 227, 233-242.
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CHANGES IN SEA LEVEL EXTREMES ALONG THE EAST COAST OF INDIA AND AT
THE HEAD OF THE BAY OF BENGAL
A.S. Unnikrishnan1, Charls Antony1 and Philip L. Woodworth2
1
2
National Oceanographic Center, Liverpool, U.K.
Changes in extreme sea levels along the east coast of India and at the head of the Bay
of Bengal are studied by analyzing hourly tide gauge data at Visakhapatnam, Chennai and
Hiron Point. At Hiron Point, the increase in the 99th percentile of sea level shows an increase
of 5.2 mm/yr, which is consistent with changes in mean sea level. This tide-gauge station is
located on the deltaic region. A similar increase in mean sea level rise trend has been
reported from the record at Diamond Harbour (Kolkata), which is partly attributed to
subsidence of the delta.
The Hiron Point record also shows the presence of lunar perigean subharmonic cycles
of 4.4 year period. The amplitudes of the perigean subharmonic cycles also contribute to the
extreme sea level variability over interannual time scales.
The 99th sea level percentile time series at Hiron Point, Visakhapatnam and Chennai
are correlated with indices of regional climate modes such as IOD and ENSO. It is found that
extreme sea level is correlated well with the climate mode indices suggesting that
interannual variability associated with IOD and ENSO also influences the height of sea level
extremes in the Bay of Bengal.
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UNDERSTANDING SEASONAL CHANGES OF GOA BEACHES USING EMPIRICAL
ORTHOGONAL FUNCTION METHOD
Yadhunath E.M* and Jaya Kumar Seelam
Miramar, Candolim and Baga are some of economically important beaches of Goa,
India (Fig. 1). Information on the erosion/accretion of these beaches is important for the
efficient management of these beaches. Beach profile measurements were carried out from
these beaches at monthly intervals over a period of more than one year. These time series
measured data are analyzed statistically by Empirical orthogonal function (EOF) also known
as Principal component analysis (PCA) method. These beach profile data were linearly
interpolated so that all the profiles during different dates have points that are equidistant
apart. The objective of this analysis is to represent the data as a function of time and space
[Winant et al., 1975]. This technique is useful to understand the spatial and temporal
variations of the beach. EOF analysis basically used in beach morphology studies to explain
point of greatest variation in the beach profiles, or point of onshore offshore sediment
exchange [Aubrey, 1979]. One of the major advantages of EOF analysis is that we can
understand the variations of beach at each point along the beach. From this study, it is
observed that from February 1999 to April 2000 Calangute, and Miramar beach showed net
accretion behaviour despite the occurrence of sediment erosion during Southwest
Monsoon. However, sediment erosion was observed at Baga Beach.
Fig 1: Study area
References:
D.G. Aubrey (1979) Seasonal patterns of onshore/offshore sediment movement. Journal of
Geophysical Research: Oceans, 84, 6347-6354.
C.D. Winant, D.L.Inman & C.E.Nordstrom (1975). Description of seasonal beach changes
using empirical eigenfunctions. Journal of Geophysical Research, 80, 1979-1986.
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TIDAL CURRENT ENERGY ASSESSMENT IN THE GULF OF KHAMBHAT
Aqleema Shah1 and Manasa Ranjan Behera2
1
National Institute of Technology Srinagar, Jammu &Kashmir
Indian Institute of Technology Bombay, Mumbai; [email protected]
2
The present dependence on exhausting fossil fuels had lead to a hunt for reinstating
the depleting resources by a sustainable and renewable one. The recent developments in
the field of ocean energy extraction signify that the source can be considered as a potential
boon to aid national needs. The tidal energy extraction is mainly processed by two main
approaches; one is to construct barrages and the other is to install underwater turbines in
locations where high tidal current velocities exist (Bedard et al., 2005).
Various studies and measurements have pointed that the Gulf of Kachchh, Gulf of
Khambhat and Sunderbans are region of high tidal range and currents in India (Ministry of
New and Renewable Energy - Tidal Energy, 2013). Gulf of Khambhat, located along the west
coast of India, is a potential region in the Arabian Sea where tidal energy is abundant. There
is a tidal amplification of about three folds from mouth to the head of the Gulf, along with
which the tidal current is expected to be increase along the channel.
This paper presents an effort towards evaluation of tidal currents and possible power
potential through 2-D modelling of the tidal dynamics in the Gulf of Khambhat. A 2D shallow
water equation model was used with a finite element formulation. It was applied to a
domain spanning between 16°N – 22.5°N and 70°E – 74°E (Fig.1a). The domain with
interpolated bathymetry from GEBCO is shown in Fig.1(b). The model was forced with tidal
elevation from the open/ocean boundaries and simulation was carried out for duration of 1
month. Tidal elevations and currents across the domain were computed and the average
current velocity for 1 month duration is presented in Fig.1(c). It is observed that a large
region in the Gulf of Khambhat has current velocity higher than 1.0 m/s, which is the cut-in
speed for most of the tidal turbines (Bedard et al., 2005). It suggests that there is a high
possibility of harnessing tidal kinetic energy from Gulf of Khambhat. The current velocities
extracted from the model are compared with the in situ measurements of tidal current data
(Unnikrishnan et al., 1999) for a location (Bombay High) as shown in Fig.2. The comparison
shows good agreement of the model results with the measurements. The computed
velocities were used to obtain the available theoretical power over the domain using the
equations given by Bryden et al., (1998). The average theoretical power for 1 month in the
Gulf of Khambhat region is shown in Fig.3. This shows that abundant power potential is
present in the domain; however, based on a feasibility study the actual extractable power
can be obtained. The study can be used as a preliminary analysis for detailed estimation of
efficient tidal power extraction sites.
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Fig.1. (a) Gulf of Khambhat region along Indian Coast (b) Bathymetry of the domain and (c)
Average current velocity (m/s) over 1 month duration
Fig.2. Comparison of depth averaged
currents (m/s) between measured data
(Unnikrishnan et al., 1999) and present
model results.
Fig.3. Available average power (KW/m2) for
1 month duration
References
A S Unnikrishnan, S. R. Shetye and G. S. Michael (1999). Tidal Propagation in Gulf of
Khambhat, Bombay High and surrounding areas. Proceedings Indian Academy of Sciences
(Earth Planet. Sci.), 108, No. 3, 155–177
Bedard. (2005). Survey and Characterization Tidal In Stream Energy Conversion ( TISEC )
Devices, EPRI-TP-004-NA, pp. 1–185
Bryden, I. G., Naik, S., Fraenkel, P., & Bullen, C. R. (1998). MATCHING TIDAL CURRENT
PLANTS TO LOCAL FLOW. Energy Procedia, 23(9). 699–709. Elsevier Science Limited
Ministry of New and Renewable Energy - Tidal Energy. (2013). Retrieved from
http://www.mnre.gov.in/schemes/new-technologies/tidal-energy/
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PRELIMINARY RESULTS OF UNDERWATER VERTICAL AND HORIZONTAL
VISIBILITY OF THE COASTAL WATERS OF GOA
Shreya S. Joshi1*, T Suresh1, Anil Kumar2
1
2
Naval Physical Oceanography Laboratory, Kochi, Kerala
Underwater visibility is the ability of human to detect objects in water and it is
measured as the distance an object can be identified from the observer. It has importance
and relevance to the Navy, marine archaeology, salvage operations, maintenance of ships,
inspections of underwater structures, studies of marine flora and fauna and for leisure
sports. Underwater visibility is a function of three factors - underwater environment, the
object to be recognized or identified and the diver or observer. In our studies we have used
the Secchi disk to measure vertical visibility and the optical parameters to model visibility.
We have used two models to determine the vertical visibility, based on the visibility contrast
model (Weber contrast) [Tyler, 1968, Preisendorfer, 1986] and the second approach based
on the modulation transfer function [Hou et al, 2007]. The horizontal visibility is determined
using a model based on a self-consistent approach using the radiative transfer model
[Haltrin, 1999] and the contrast model. These models were evaluated using the optical
properties of water which were derived from the in-situ measurements and also from
radiative transfer simulations. The in-situ data used for the studies were measured in the
coastal waters of Goa, India. Since the eye perceives photopic parameters, the models are
all based on photopic parameters. The spectral radiometric optical properties were
converted using empirical relations to photopic luminosity parameters, using the photopic
luminosity function of the eye.
The range of vertical visibility (Secchi depths) was 1 to 8.6 m. The photopic beam
attenuation varied from 0.55 to 7.86 (m-1) and diffuse attenuation from 0.223 to 0.918 (m-1),
while the underwater average cosine was limited to a narrow range of 0.603 to 0.783. The
coupling parameter Γ is an important parameter and is related to contrast, as   ln  C0 
C 
 min 
where C0 is the inherent contrast between the target and background water and C min is the
minimum apparent contrast perceivable by the human eye under photopic conditions. The
coupling parameter Γ derived using the contrast model of Preisendorfer [1986] is reported
to vary between 6 to 9 [Tyler, 1968] and for our study it varied between 6.4 to 7.89 with a
mean value of 7.24.
The vertical visibilities derived from the models closely matched the measured (R 2 =
0.98) for the model of Hou [2007] and (R2 = 0.98) for the model of Preisendorfer [1986]. The
horizontal visibilities evaluated using the model of Haltrin [1999] were within the range of
2.29 and 9.81 m [Fig.1]. The horizontal visibility was about 1.3 times the vertical visibility.
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Fig. 1. Comparisons of measured vertical visibility with the models (Left) and the comparison
between vertical and horizontal visibility.
The coupling parameter Γ is modelled as a function of underwater average cosine at
490 nm and the vertical visibilities were derived using the contrast model with the
measured optical parameter [Fig.2]. The model was compared with the measured vertical
visibility. The measured vertical visibilities were in the range 0.79 to 4.18 m. The results of
validation using our empirical algorithm were encouraging, with high correlation between
model and measured with R2 = 0.85, mean percent deviation (MPD) of -22% indicating to be
slightly underestimated and root-mean squared error (RMSE) of 0.5.
Fig. 2. Comparison of our model and the measured vertical visibility.
References:
Haltrin, V. I. (1999), Horizontal visibility of Lambertian object submerged in seawater, IEEE
1999 International Geoscience and Remote Sensing Symposium, IGARSS’99 (Cat.
No.99CH36293), 2(99), 1417–1419.
Hou, W., Lee, Z., and Weidemann, A. D. (2007), Why does the Secchi disk disappear? An
imaging perspective, Optics Express, 15(6), 2791.
Preisendorfer, W. (1986), Secchi disk science: Visual optics of natural waters, 3(September).
Tyler, J. E. (1968), The Secchi disc. Limnology and Oceanography, XIII(1), 1–6.
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MARINE BIOLOGY
SESSION - 06
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BIODIVERSITY AND STATUS OF CORAL REEF IN MALVAN MARINE
SANCTUARY, CENTRAL WEST COAST OF INDIA
Kalyan De1 , Sambhaji Mote1, Lobsang Tsering1, Perisamy, R.1, Vishal Patil1, Rahul Nagesh1 ,
Afreen Hussain1, Sabyasachi Sautya2, Baban Ingole1*
1
CSIR-National Institute of Oceanography, Dona Paula Goa, India; [email protected]
2
CSIR-National Institute of Oceanography, Regional Centre Mumbai, India
Coral reefs are one of the most important and spectacular marine ecosystem. In India,
major coral reef formations are restricted to the Andaman and Nicobar Islands, Gulf of
Mannar and Palk bay in Bay of Bengal and on the other side Gulf of Kutch, the Lakshadweep
islands in the Arabian Sea. While apart from these reefs there are some patchy fringing reefs
also present along the central west coast of India. The Malvan Marine Sanctuary (MMS) is
blessed with one of such coral reef formation. The area is declared as Marine Protected
Area (MPA) in 1987 under the Wild Life Protection Act, 1972. It covers an area of 29.122 km2
and considered as one of the ‘Biodiversity hotspot’. Earlier studies reported 74 species of
fishes, 73 species of seaweed and 9 coral species including 181 species associated flora and
fauna. The present study was initiated to evaluate the degree of the biodiversity, health and
threats to the coral reef and its environment. Subtidal underwater survey by SCUBA diving
and snorkeling was conducted at five locations in the reef region and one location out of the
reef area. Belt Intercept Transect (BIT) and quadrate survey methods were employed to
assess the biological community structure and composition. The reef area extended
between shallow intertidal zone to the 15m in subtidal zone. Average water depth ranged
between 3-5 m. Alltogeather 16 of species of building scleractinian coral (Montipora
aequituberculata, Cyphastrea serailia, Pseudosiderastrea tayami, Siderastrea savignyana,
Favites bestae, F.halicora, Turbinaria mesenterina, T. frondens, Porites lichen, P. lutea, P.
compressa, P. astreoides, Goniopora stokes, G.minor), were recorded. Encrusting coral
P.tayami and P.lichen were dominant in the intertidal to shallow zone, whereas foliaceous T.
mesenterina was conspicuous in the mid-region. G. stutchburyi and P. versipora were the
dominant in the deeper region. Overall coral coverage is dominated by stress tolerant T.
mesenterina. Despite being a MPA, there has been a noticeable degradation and breakage
of corals documented perhaps due to the unregulated tourist trampling, inexperienced
diving activities, disturbance in the bottom the sediment by boat anchoring on the reefs flat.
Moreover, the coral bleaching observed in several locations on the reef flat signifies the
human and environmental pressure on the reefs. Macroalgal coverage was dominated by
Sargassum spp. and invasion of turf algae on the coral colonies was also observed. Strong
wave action, high turbidity and anthropogenic pressure indicate the adaptability of the coral
species to such environment. Awareness creations among the local community, promotion
of eco-friendly tourism and strict implementation of legal provisions need to be initiated to
protect the reef’s sustainability.
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BENTHIC FLAGELLATE COMMUNITY DISTRIBUTION IN RELATION TO ABIOTIC
AND BIOTIC VARIABLES ALONG THE NORTH EAST COAST OF INDIA, BAY OF
BENGAL
Sangeeta Mishra1,2*, Rakhesh Madhusoodhanan1,3, Kalavati Chaganti1, Raman V Akkur1
1
Marine Biological Laboratory, Dept. of Zoology, Andhra University, Visakhapatnam, India – 530003;
[email protected]
2
State Pollution Control Board, Orissa, Bermunda, Bhubaneswar, India – 751003
3
Department of Biology, University of Bergen, Bergen, Norway- 5020
Heterotrophic flagellates are considered as an important component of microbial
communities in all types of aquatic ecosystems. Samples were collected from 27 GPS fixed
locations along a stretch of 152 km on the northeast coast of India at three different
habitats (estuarine, inter-tidal and rock-pool) during February 2007 – July 2008. For
qualitative analysis the surface sediments collected up to a depth of about 1 cm of 1 m2
quadrate using a flat spoon. The sediments were placed in plastic trays in 1 cm deep layers.
Cover slips (No1. 22×22mm) were placed on lens tissue laid on the sediments. After 12 to 24
h, flagellates were observed using (Leica DMLS) with x400 microscope equipped with
photographic facilities. Altogether 64 numbers of flagellates were observed. Numerically
flagellate abundance varied from a minimum of 10 nos.g-1 (March 2007) to a maximum of
27118 nos.g-1 (September 2007) and the observed mean was 1159 nos.g-1. Based on the
numerical abundance, 16 species which together constituted 90% of the population were
considered as important. Anisonema sp. (12.4%), Goniomonas sp. (9.2%), Bodo sp. (8.6%), B.
cephalophorus (8.3%), Chloromonas sp. (8.3%) and Dinematomonas sp. (7.7%) were
important in order of their abundance. Overall, phytomastigophoreans formed the bulk
(77.8%) of the population numerically. Habitat-wise, the estuary appeared to support a rich
population of flagellates. Mean abundance ranged from 4344 nos.g -1 to 5970 nos.g-1 and
mean being 5354 nos.g-1. During this study, heterotrophic flagellate abundance is
significantly correlated with sediment chlorophyll (an attribute of phytobentios) and
negatively with nitrite, nitrate and phosphates (considered as sources of bacterial
production). Through Bray-Curtis similarities it was possible to divide the 27 stations into
three groups at 48% similarity. The dendrogram provided a sequence of fairly convincing
groups of stations confirmed by MDS plot for the same locations. ANOSIM Global test
indicated a significant difference (Global R: 0.98 at 0.1%) in the composition of flagellate
assemblages among these habitats. The SIMPROF test also revealed a good demonstration
of both ANOSIM and SIMPROF working in conjugation. Overall it may be concluded that
locally both in the coastal and estuarine sediments, heterotrophic flagellates are euglenoid
dominated and showed a strong segregation into different assemblages in different
habitats. Seasonal changes were less marked. More than the abiotic factors, feed availability
appeared a major controlling factor for heterotrophic flagellate abundance and diversity.
References:
S.K.Sasamal, R.C.Panigrahy, Sangeeta Mishra (2005) Asterionella blooms in the
northwestern Bay of Bengal during 2004. International Journal of Remote Sensing, 26(17),
3853-3858.
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Sangeeta Mishra, Gouri Sahu, A.K.Mohanty, S.K.Singh and R.C.Panigrahy. Impact of the
diatom, Asterionella glacialis (Castracane) bloom on the water quality and phytoplankton
community structure in coastal waters of Gopalpur sea, Bay of Bengal (2005). Asian Jour.
Water, Environment and Pollution. 3 (2): 71-77.
241
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MACROBENTHIC COMMUNITY STRUCTURE IN RELATION TO STRESSORS IN A
FISHING HARBOR OF PARADIP, ODISHA, EAST COAST OF INDIA
Dipti Raut*, Himadri Tanaya Panda, Aswini Nayak, Biswaprajna Mohanty, Lipika Patnaik
Environmental Science Laboratory, Department of Zoology, Ravenshaw University, Odisha -753003;
[email protected]
Hydrobiological studies in a Fishery harbor in Paradip (Lat 20° 15' 55, 44" N; Long 86°
40' 34.62"E), Odisha, to assess water quality, sediments and benthic fauna in relation to
anthropogenic activities revealed 24 species of organisms belonging to diverse groups of
animals such as Polychaetes, Crustaceans, Molluscs and Pisces. Of these polychaetes
outnumbered other groups both in terms of their diversity and population density (91%),
being represented by as many as 14 species. Numerically polychaetes such as the Spionids,
Prionospio sp., Polydora sp., Cossurid, Cossura sp., Capitellid, Capitella sp. and Nereid,
Nereis sp. were dominant (~70%). In this investigation the complete absence of Maldanids,
Lumbrinereis and Terebellids is of interest as their absence is an indication of poor
environmental conditions. On the transects closer to the jetties, diversity indices such as the
Shannon-Wiener index H’ and Margalef index d were relatively low (<1.37) in comparison to
the central transect (>1.69) indicative of stressors such as higher organic load (>1.9%), lower
dissolved oxygen (sometimes nil) and increased trawler movements scouring away the
sediment infauna, direct dumping of ballast water, trash fish, fish viscera from gutting to
name a few. Different faunal groups characterize the transects such as Prionospio-PolydoraCirratulids-Capitella-Cossura sp. on the west, while Nereis- Capitella sp. on the east and
Lycastis-Cossura sp. in the central transect. The presence of Capitellids in the marginal
transects is clearly indicative of organic enrichment and gross polluted conditions. BrayCurtis similarity for benthic fauna revealed three groups at 59% similarity characterizing
mouth locations (T4 andT5), mid harbour (T1 and T3) and an independent T2 cluster.
Overall, the study revealed characteristic response gradients in the composition and
distribution of benthic fauna in relation to sediment nature (texture, organic content) and
other physico-chemical characteristics.
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STUDY OF CESTODE INFECTION IN SCOLIODON IN MUMBAI REGION, INDIA
V. V. Andhare*, P. Hatkar and S. Soni
Institute of Science, Fort, Mumbai; [email protected]
Scolidon is consumed as food by most of the people of Mumbai region. It is a common
fish which is seen in markets of Mumbai and is also a source of income to fishermen. The
population dynamics of Scolidon was studied to see the infection rates of endoparasites
specifically the cestodes during the three seasons from November 2012 to December 2013.
The methods include statistical applications to know the population levels and distribution
of cestode parasites during the above mentioned period.
The present study deals with the rate of infection of cestode parasites in the intestines
of Scoliodon from the landing centres of Mumbai during November 2012 – December 2013.
The intestines of Scoliodon were procured from 3 landing centres of Mumbai viz,
Bhaucha dhakka, Sasson Dock and Versova Dockyard during the period of 12 months from
November 2012 – December 2013. The intestines were dissected longitudinally and
observed for infections. Parasites were collected in warm water and stored in 10% formalin.
Further they were stained in Harris haemotoxyline and identified upto genus level.
Population dynamics of cestode parasite were determined by the following formulae:
Incidence of infection = (Infected host/ Total hosts examined) x 100
[1]
Intensity of parasites = (No. of parasites in a sample/ No. of infected host)
[2]
Index of infection parasite =
(
)
(
)
[3]
A total of 360 intestines were collected and examined, out of which only 144
intestines were infected and a total of 302 cestode parasites of different genus were found.
The value of incidence, intensity and index of parasite infection are as 40%, 2.04% and 0.54
respectively.
Thus the above observation and results show that Scolidon was infected by a number
of cestode parasites from different genera like Tetrarhynchus, Nybelinia, Tylocephalum,
Phyllobothrium etc. The infection of these parasites was the highest during January to April
as the high temperature enhances the hatching of the eggs of parasites, whereas from
October to December the infection rate was low as it is the winter season.
References:
Sandeep, A., Sushil, J. and Sunita, B. (2011), Population dynamics of cestode parasite in
Trygon zugei from Ratnagiri district (M.S.), India International Multidisciplinary Research
Journal, 1(8) 24-26.
Mani, G., Anu, P. V. and Vijayalakshmi, C. (2012), Population dynamics of metazoan
parasites of marine threadfin fish, Eleutheronema tetradactylum (shaw1804) from
Vishakhapatnam coast, bay of Bengal, Cibtech Journal of Zoology, 1(1),14-32.
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Sarah, A. J., Vladimir, M., Sami, A. S., Redha, B. F. and Nashwa, A. M. (2014), Biological
and Ecological Features of Poecilancistrum Sp. Plerocercoid (Cestoda: Trypanorhyncha)
Infection of Arabian Sea , Journal of Research & Development Aquaculture , 5(3).
Robert, F., Boy, V. and Gabrion, C. (1990), Biology of parasite populations: population
dynamics of bothriocephalids (Cestoda-Pseudophyllidea) in teleostean fish, Journal of Fish
Biology, 37(2), 327–342.
Carvalho, A. R. and Luque, J.L. (2011),Seasonal variation in metazoan parasites of Trichiurus
lepturus (Perciformes: Trichiuridae) of Rio de Janeiro, Brazil, Braz. J. Biol, 71(3), 771-782.
244
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STRESS RESPONSE TO VARIATIONS IN TEMPERATURE IN FRESHWATER FOOD
FISH PANGASIANODON HYPOPHTHALMUS
S. Soni* and V. V Andhare
The Institute of Science, Fort, Mumbai; [email protected]
Stress is an organismns reply to any stimulus or the environment. Fish being aquatic,
its physiology and homeostatis regulation is completely dependent on the water in the
surrounding environment. Changes in the surrounding water temperature bring about
fluctuations in the regulation of homeostasis in fish resulting in stress to the fish. There are
alterations in the hormonal and blood parameters and also in the behaviour of the fish. This
in turn affects the growth rate, reproduction, lifespan, social behaviour etc of the fish. The
present work deals with the study in changes in haemoglobin values and the behaviour
mechanisms in the fresh water food fish Pangasianodon hypophthalmus. P. hypophthalmus,
a catfish is a common staple food fish worldwide.
Around 120 fish were examined macroscopically in order to observe for any symptoms
of diseases or infestation of ectoparasites (Qang, 1998; Woo, 1995; Bullock., 1989). The fish
were acclimatized for 15 days under laboratory conditions prior to experimentation. The
fish were subjected to varying temperature ranges from 240C-330C for 24 hrs. Immediately
after
experimentation,
haemoglobin
concentrations
were
determined
by
Cyanmethaemoglobin method (Blaxhall and Daisley, 1973; Tanyer, 1985). The various
behavioural activities such as sheltering, grouping and surfacing pertaining to the above
experiments were observed. The results were calculated using students‘t’ test. The Hb
(haemoglobin) mean values for 24°C, 27°C, 30°C and 33°C are 15 + 0.48, 21.06 + 1.68, 30.70 +
0.50 and 31.66 + 1.52 respectively.
Behavioural responses observed showed no change in behaviour at 24°C and 27°C,
whereas at 30°C and 33°C, the fish showed deviation from normal behaviour. At higher
temperatures the fish started surfacing for oxygen and preferred being hidden. Fish were
also seen swimming alone and not in groups.
From the observations it is concluded that the parameters like haemoglobin and
behaviour showed considerable changes when the fish were subjected to various
temperatures. The fish undergoes stress resulting in its physiological changes and
alterations in its hormones and blood parameters which may also affect the humans that
consume it for a longer duration.
References:
Kucukgul, A and Aysel, S. (2008), Acute Stress response in Common Carp (Cyprinus Carpio
Linnaeus, 1758) of some stressing factors, Journal of Fisheries Sciences, 2(4), 623-631.
Acerete, L., Balasch, J.C., Espinosa, E., Josa, A and Tort, L. (2004), Physiological responses in
Eurasian perch (Perca fluviatis, L.) subjected to stress by transport and handling,
Aquaculture Elsevier, 237, 167-178.
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Kubilay, A and Gulsen, U. (2002), Acute stress on Rainbow Trout (Oncorhynchrus mykiss),
Turk J Zool, 26, 249-254.
Saglio, P and Trijasse, S. (1998), Behavioural responses to Atrazine and Diurion in Goldfish.
Arch, Environ. Contam. Toxicol, 35, 464-491.
Cataldi, E., Dimarco, P., Mandich, A. and Cataudella, S. (1998), Serum Paraeters of Adriatic
Sirgeon Acipenser naccarii (Pisces: Acipensiformes): effects of temperature and stress,
Comparative Biochemistry and Physiology Part A, Elsevier, 121, 351-354.
Barton, B.A. (1997). Stress in Finfish in G.k. Iwama, A.D. Pichering, J.P. Sumpter, C.B. Schreck,
editors, Fish Stress and Health in Aquaculture, Cambridge university press, Cambridge,
34pp.
Little, E. E., Richard. D., Boris. A. F. and Vera. I. K. (1990) Behavioural indicators of sublethal
toxicity in Rainbow Trout, Arch. Environ. Contam. Toxicol, 19, 380-385.
Bullock, A.M. (1989), Laboratory Methods In Roberts R.J and B. Tindall, editors, Fish
Pathology, London, 372-402.
Blaxhall, P.C and Daisley K.W. (1973), Routine haematological methods for use with fish
blood. Journal of Fish Biology, 5, 771-882.
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STUDY OF BENTHIC FAUNA IN THE NEAR SHORE WATERS OFF GULF OF
KUTCH, NORTH WEST COAST OF INDIA.
Shivanagouda .N. Sanagoudra*, U. G. Bhat
Department of Marine Biology, Karnataka University, P.G. Centre, Karwar, Kodibag, Karwar 581 303,
Karnataka; [email protected]
The present study was undertaken for a period of two years from December 2010 to
May 2012. Studying the benthos of Gulf of Kutch near shore waters is also useful in
understanding changes in biological diversity of Gujarat coast. The use of benthos in aquatic
ecological research is especially effective in assessing long term changes and detecting input
from diffuse sources. The benthos reflects the effects organic enrichment by responding
through detectable changes in population dynamics on a time scale of months to years. This
is in contrast to plankton which shows a more immediate change to point sources with no
long term consequences to the populations (Gray et al 1992). Benthoses were collected
from 6 near shore water stations on regular basis and were identified. Altogether 60 species
were identified and placed taxonomically during the course of investigation with sediment
samples. Benthic environmental relationship species and their limiting biotic and abiotic
factors were observed.
Our studies of monthly comparisons have become an interesting and popular
approach in ecology and environmental relationships in the past a number of studies have
been conducted on the ecology of macro benthic populations of Gulf of Kutch near shore.
My research helps in Gulf of Kutch of the west coast of India has become an important
economic asset of the country serving commercial navigation and the fishing sector with
environmental relation of benthos in the Gulf of Kutch Gujarat. India.
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SPATIAL AND TEMPORAL VARIATIONS OF COLORED DISSOLVED ORGANIC
MATTER IN THE ESTUARINE AND COASTAL WATERS OF GOA.
Albertina Dias1*, T. Suresh1, Manguesh Gauns1, Arvind Sahay2, Prakash Chauhan2
1
CSIR-National Institute of Oceanography, Goa, India; *[email protected]
2
Space Application Centre, ISRO, Ahmedabad, India
Dissolved organic matter (DOM) is a major reservoir of organic carbon and CDOM is
the optically active component of DOM that passes through 0.2 micron filter paper and
interacts with UV and visible light. CDOM plays a key role in the penetration of UV light in
the water column and interaction with aquatic ecosystem. Coastal and estuarine waters are
complex and since CDOM has a major contribution to the optical properties hence studies
were carried out in waters of Goa from March to Dec, 2014.
Fig 1: Spatial and temporal variation of a375 nm-1
The CDOM absorption at a reference wavelength of 375 nm, a375 (Fig 1) in the coastal
waters was found to decrease offshore in all the seasons. In the coastal waters, during the
post monsoon and summer, a375 was found to be the highest while it was the lowest during
the winter. In the Mandovi and the Zuari estuaries absorption at a375 increases towards the
head of the estuary. In the Mandovi estuary, the absorption was found to be high in the
summer at the head and then decreases towards the mouth. During winter the absorption
was high at the mouth of the estuary and low at the head. In the post monsoon the
absorption was the lowest in both the estuaries.
Fig 2: Spatial and temporal variation of S250-600 nm-1
The slope S250-600 in coastal waters was low during summer and increases through post
monsoon and was the highest in winter. The general trend in Mandovi estuary of S250-600 was
found to be high in winter and lowest during post monsoon, while in the Zuari estuary it
followed a reverse trend with high S250-600 in the summer (Fig 2).
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Fig 3: Spatial and temporal variation of S275-295 nm-1
The S275-295 is a good proxy for photo-bleaching (Helms, 2008), which was found to be
high in the coastal waters during winter. In the Mandovi and Zuari estuaries S275-295 was
found to be high in summer and low during post monsoon (Fig 3).
In the coastal waters SR which is a ratio of S275-295/ S350-400 varied from 1.6 to 2.4. It is
low at the coast and increases offshore. In the Mandovi estuary, SR increased from the head
to the mouth of the estuary. SR was high during summer and almost similar during the
winter and post monsoon. In the Zuari estuary minimal seasonal variations of SR were
observed.
Fig 4: Variation of a365 with salinity
The estuaries and coastal waters in Goa show non conservative behaviour of CDOM as
seen in Fig 4. Addition of CDOM was seen in all seasons in the estuaries. In the coastal
waters, removal was dominant during winter and summer which may be assigned to photo
bleaching indicated by high value of S275-295. The high value of S275-295 in the coastal waters
indicates that photo bleaching is a perennial problem in these waters
References:
Helms, J. R. et al (2008), Absorption spectral slopes, and slope ratios as indicators of
molecular weight, source, and photobleaching of chromophoric dissolved organic matter,
Limnol. Oceanogr., 53, 955–969.
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STUDY OF EPIPHYTIC DIATOMS ON SEAWEEDS AND ASSESSING THEIR
POTENTIAL AS POLLUTION INDICATORS
V. A. Kulkarni1*, S. P. Jagdale2
1
rd
Cholamandalam MS Risk Services Limited, QCI Accredited EIA Consulting Organization, 3 Floor, Wellesly
Court, Dr. Ambedkar Road, Pune 411001; *[email protected]
2
Dapoli Urban Bank Senior Science College, Affiliated to Mumbai University, Dapoli, Maharashtra 415 712
Epiphytic floras of marine macrophytes prominently constitute diatoms, cyanobacteria
and fungi [Dere et al., 2002]. Epiphytic diatoms are of a special interest because of their
attachment to living substrate and interactions among different components of habitats.
Most of the earlier work done on epiphytic diatoms dealt with freshwater and estuarine
environments [Sullivan and Currin, 2000]. The limited mobility of epiphytic diatoms makes
them likely to reflect long term environmental conditions for a particular area [Fore and
Grafe, 2002]. Therefore, they potentially can be use as bioindicators of environmental
quality, and may be more effective than other conventional bio-indicators [Fisher and
Dunbar, 2007]. Understanding dynamics of epiphytic diatom community would enable
exploring their ecological, environmental as well as bioindicator potentials.
The study area selected for this research is central west coast of India which lies
between latitude 15° - 17°N and longitude 73° 15’ - 74° 30’E. Sampling locations selected
along central west coast were Mumbai, Malvan and Anjuna. Seaweed flora along selected
stations was surveyed on monthly interval basis during the period of November 2012 to
October 2013, using standard seaweed collection procedure [Dhargalkar et al. 2001].
Epiphytic diatoms on seaweeds’ thalli were isolated by adopting and slightly modifying
the HCl digestion methods described for aquatic angiosperms [Shamsudin and Sleigh, 1995].
Total abundance was estimated as No. X 105 g-1 Dry Weight of thallus. Diatom samples were
identified as described by Desikachary et al. [1987] and Tomas [1997]. Statistical analysis of
data was conducted using PRIMER E6 software. Seawater quality at selected locations was
studied using standard methods [Strickland and Parson, 1972].
pH, temperature, salinity, dissolved oxygen and suspended solids were observed to be
in normal range and nearly similar at all three locations. However, biological oxygen demand
and nutrient values were much higher at Mumbai than that of Malvan and Anjuna.
A total of 62 diatom species were recorded to be epiphytic on seaweeds during study.
Licmophora and Biddulphia dominated epiphytic diatom community from Mumbai with
average percentage composition of 57.06% and 10.62%, respectively. Rhizosolenia was
observed to be dominant on seaweeds from Malvan [22.86%] and Anjuna [41.38%]. In
Malvan and Anjuna Navicula, Nitzschia, Grammatophora and Caloneis spp were also found
to be dominant during the sampling period. Epiphytic diatom community at Mumbai
showed totally different distribution and abundance patterns as that of Malvan and Anjuna.
The cluster analysis of epiphytic diatom communities revealed that diatom
assemblages at Mumbai are significantly different from other two locations. Though
composition of diatoms assemblages displayed wide temporal variations at Malvan and
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Anjuna, specimens from Mumbai were found to be supportive of one species community
hypothesis. The results of draftsman plot show that diatoms such as Biddulphia, Licmophora
and Nitzschia observed at Mumbai had strong and positive correlation with pollutant
parameters and negative correlation with dissolved oxygen. Similarly Rhizosolenia and
Navicula showed negative correlation between pollutant parameters.
Non linear and negative relationship was observed between Rhizosolenia with
Biddulphia, Licmophora and Nitzschia. This indicates Rhizosolenia cannot tolerate the
environmental conditions in which abundance of Biddulphia, Licmophora and Nitzschia
found to be high. Hence Rhizosolenia could act as bioindicator for cleaner water.
Licmophora and Nitzschia though showed positive relationship with pollutants, they were
occasionally observed at Malvan and Anjuna. However, Biddulphia exclusively occurred at
Mumbai and dominated most of the epiphytic population. Hence, it could act as
bioindicator for polluted water.
References:
Dere P, Karacaoulu D. and Dalkiran N. [2002] A Study on the Epiphytic Algae of the Nilufer
Stream [Bursa]. Turkish Journal of Botany. 26: 219 – 233.
Desikachary TV, Prasad AKSK, Hema P, Sreelatha M, Sridharan VT and Subrahmanyan R
[1987] Marine diatoms from the Arab Sea and Indian Ocean, in: Desikachary TV [ed.], Atlas
of diatoms. Fasc. IV. Madras Science Foundation, Madras. 1 – 7.
Dhargalkar V.K., Untawale A.G. and Jagtap T.G. [2001] Marine Microalgal Diversity along
Maharashtra coast - Past and Present Status. Indian Journal of Marine Sciences. 30: 18 – 24.
Fisher J. and Dunbar M.J. [2007] Towards a representative periphytic diatom sample.
Hydrology and Earth Systems Science. 11: 399 – 407.
Fore L. and Grafe C. [2002] Using diatoms to assess the biological condition of large rivers in
Idaho [U.S.A.]. Freshwater Biology. 47: 2015 – 2037.
Shamsudin L. and Sleigh M.A. [1995] Seasonal-Changes in Composition and Biomass of
Epiphytic Algae on Themacrophyte Ranunculus penicillatus in a Chalk Stream, With
Estimates of Production, and Observations on The Epiphytes of Cladophora glomerata.
Hydrobiologia. 306 [2]: 85 – 95.
Strickland JDH and Parsons TR [1972] A practical handbook of seawater analysis. Fisheries
Research Board of Canada. 310 pp.
Sullivan M.J. and Currin C.A. [2000] Community structure and functional dynamics of
benthic microalgae in salt marshes. In: MP Weinstein and DA Kreeger [Eds.], Concepts and
Controversies in Tidal Marsh Ecology. Kluwer Academic Publishers, Dordrecht: 81-106.
Tomas C.R. [1997] Identifying Marine Phytoplankton. Ed. Carmelo R. Tomas. Academic
Press. 858 pp.
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SPATIAL AND TEMPORAL COMMUNITY CHARACTERISTICS OF ASSOCIATED
ORGANISMS IN SARGASSUM CINCTUM
Wasim Ezaz*, Temjensangba Imchen
CSIR-National Institute of Oecanography, Goa; [email protected]
Sargassum cinctum is a typical brown macroalga found growing on the rocky
substratum of intertidal and subtidal region. This study attempted to analyze the spatial and
temporal variation in community dynamics of associated organisms in relation to
Sargassum. More than 31,000 individual species from 8 major taxa were isolated in the
present study and they were analyzed qualitatively and quantitatively to describe
abundance, species richness and the host specificity of associated organisms. The total
community structure showed a positive correlation with plant architecture. The fauna
lacked diversity but a few species were found frequently across the year namely amphipods
(Gammarus fasciatus, Gammaropsis sp.) and Bivalvia (Modiolus sp.). Most species increased
their abundance during the cool season while during summer season the abundance of alga
and associated fauna decreased in relation to summer temperature. Comparison of major
groups representing Amphipods, Isopoda, Polychaeta and Bivalves from different sampling
period indicated that although the temporal variation exhibited higher effect on the
community structure, no species showed any significant variation in terms of abundance.
Gammarus fasciatus (Amphipoda) was found to be the most abundant species associated
with the target alga throughout the study period in the present study.
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ARABIAN SEA LONG TERM PRODUCTIVITY TREND
Prince Prakash1* and Satya Prakash2
1
National Centre for Antarctic and Ocean Research, Vasco-da-gama, Goa; [email protected]
2
South-western Arabian Sea is the most productive region in the Indian Ocean. Some
of the recent observations on the basis of ocean color data have shown contradicting trends
in ocean productivity for the Arabian Sea; it has increased by more than 350% over the last
6 years in the western Arabian Sea due to strengthening of the monsoonal winds [Goes et
al., 2005] whereas no such trend is seen in the eastern Arabian Sea [Prakash & Ramesh,
2007]. Analysis of SeaWIFS (9-km spatial resolution) Level-3 monthly chlorophyll-a
concentration data for the period of 1997-2010 shows a decreasing trend in the summer
chlorophyll-a for the south-western Arabian Sea (Somali Coast,47-55°E & 5-10°N) after 2003
(Figure 1). The trend analysis revealed that there was an increase in the summer peak
chlorophyll-a concentration from 1998 to 2003 (slope: 0.24 ± 0.06; r2 = 0.85; p = 0.02) but
decreased after that (slope: -0.06± 0.03; r2 = 0.44; p = 0.10). Analysis of winds (Cross
Calibrated Multiplatform wind and QuickSCAT ) strength and wind stress curl from 1997 to
2003 and from 2004 to 2009 do not show any appreciable change. During the period 1997
to 2003 Satellite derived Sea Level Anomaly (SLA) along the Somalia coast shows a
decreasing trend (Slope = -0.06 cm/month, P-value = 0.02) while during 2004 to 2010 the
SLA increases (slope = 0.07 cm/month, P-value = 0.03). The sea level change generally
reflects thermocline variation: Increase (decrease) in sea level associated with deepening
(shallow) of thermocline. This is also reflected in the depth of the 23°C (D23) isotherm,
which is a proxy for thermocline depth. Summer (June to September) average of D23 during
1997 was 130 meters which gradually decreased and shoaled upto 85 meters in 2003 and
then reached 71 meters in 2004, but after 2004 it again gradually increased and deepened
to 109 meters in 2010. As the nutricline and thermocline are closely associated in the
Arabian Sea, therefore change in thermocline directly affects the supply of nutrient to the
surface layer. Thus the deepening of the thermocline during 2003 to 2010 reduced the
supply of nutrients to the euphotic zone and a decrease in surface chlorophyll-a. Our
analysis reveals a remarkable change in trend in the chlorophyll concentration of the southwestern Arabian Sea after year 2003. Our finding suggests that the south-western Arabian
Sea could witness increase/decrees in bloom of phytoplankton not only due to the
strengthening/weakening of local wind but sea level anomaly also plays a crucial role. So
the bloom in the south-western Arabian Sea is not only due to atmospheric effect but also is
a manifestation of oceanic effects. The observed variability in productivity, therefore, may
not be an effect of the global warming but part of a decadal oscillation.
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Figure 1: Area averaged monthly time series of Chlorophyll -a for south-western Arabian Sea
(47-55°E & 5-10°N). The trend lines shown depict the increasing and decreasing trends
during 1998–2003 and 2004–2010, respectively
References:
Goes, J. I., P. G. Thoppil, H. do R Gomes, and J. T. Fasullo (2005) Warming of the Eurasian
landmass is making the Arabian Sea more productive, Science, 308, 545–547.
Prakash, S., and R. Ramesh (2007) Is the Arabian Sea getting more productive? Curr. Sci., 92,
667– 671.
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ASSESSING THE ECOLOGICAL STATUS OF COASTAL WATERS OF INDIA USING
AMBI (AZTI’S MARINE BIOTIC INDEX).
SK Sivadas1*, R. Nagesh1, B.S. Ingole1, GVM Gupta2
1
2
Centre for Marine Living Resources, Kochi, India
Marine ecosystem harbours 97% of all species on Earth but is under threat by
increased human manipulation of the ecosystem and rapid climate change. The alteration of
ecosystem has resulted in the most rapid loss of species in the history of life on Earth
(Vitousek et al 1997). One of the greatest challenges when determining the impact from any
disturbance is the inability to separate man-made impacts from natural change. This
particularly important in tropical regions where environmental variables shows distinct
temporal variability influenced by the annual monsoon which is reflected in the distribution
pattern of marine communities. Therefore, knowledge of the reference condition is
extremely useful for effective conservation plans (Bremner 2008). The benthic communities’
sensitivity to changes makes them good indicators of the ecological status of the marine
ecosytem.
There have been many biotic indices formulated to study the ecological status of
marine ecosystem. AMBI (AZTI’s Marine Biotic Index) is one such index that is presently
used worldwide to assess coastal waters. AMBI (Borja et al. 2000) is based on the ecological
group. Although AMBI has been used widely in various ecosystem (Borja et al. 2009), very
few studies have used it in tropical region. Since Indian coast is also affected by the
increasing urbanization and industrialization we calculated the AMBI index during different
season to understand the natural variation in the index and the ecological status of the
region. The study area includes Mandovi Estuary, Zuari estuary, Kalbadevi Bay, Kochi and
three harbours (Ratnagiri, Mormugao and Karwar). Five distinct temporal regimes are
identified based on the rainfall pattern - Lean-Season Regime (LSR; January-May); MonsoonOnset Regime (MOR; June); Peak-Monsoon Regime (PMR; July-August); End-Monsoon
Regime (EMR; September-October) and Post-Monsoon Regime (PMon Regime; NovemberDecember). A temporal trend was observed in the AMBI index and highest values were
observed during the monsoon (Figure 1). High values of AMBI during monsoon (MOR and
PMR) are because the overall macrofaunal community are lower during this period. In
general, highest values were observed in the harbours. Our study indicates that the AMBI
could be used to assess the health of coastal ecosystem. However, we suggest that the
AMBI index could be used with other biotic indices and abiotic factors to give accurate
results.
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5
LSR
MOR
PMR
EMR
PostMR
AMBI Index
4
3
2
1
0
Zu H
Zu E
Ma E Sampling
Rat HArea Kar H
Kal
Koc
Figure 1 Seasonal variation of AMBI index in the study area. ZuH Marmugao harbor; ZuE
Zuary Estuary; Ma E Mandovi Estuary; Rat H Ratnagiri harbor; Kar H Karwar Harbour; Kal
Kalbadevi Bay; Koc Kochi.
REFERNCES:
Vitousek PM, Mooney HA, Lubchenco J, Melillo JM (1997) Human domination of Earth’s
Ecosystem. Science 277:494-499.
Borja A, Miles A, Occhipinti-Ambrogi A, Berg T (2009) Current status of macroinvertbrate
methods used for assessing the quality of European marine waters: implementing the Water
Framework Directive. Hydrobiologia 633(1):181-196.
Borja A, Franco J, Pérez V (2000) A marine biotic index to establish the ecological quality of
soft-bottom benthos within the European estuarine and coastal environments. Mar Pollut
Bull. 40:1100-1114
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DIVERSITY OF MACROBENTHOS AND MACROPHYTE RELATIONSHIP ON THE
ROCKY SHORE
Uday Gaonkar, Periasamy R., S.K. Sivadas, Vishal Patil, B.S. Ingole*
Macrobenthic diversity is a major biological productive area on intertidal rocky
habitats and it improves ecologically diverse coastal areas. Rocky shore is one of the most
fascinating of the ecosystems and this dominates large proportion of world’s coastlines. This
rocky shore has huge diversity of macrophyte, because it provides substrate for macrophyte
which stables them on the rocky shore. The present study was initiated to evaluate the
macrophyte community enhance associated macrobenthos biodiversity at five different
rocky intertidal areas, namely Ratnagiri, Anjuna, Cabo-de-Ram, Majali and Ankola situated
on the central west coast of India. Samples were collected on January and February 2013
during low tide with quadrant intercept transects method. Spatial distribution of
macrobenthos is related to particular macrophyte species by means statistical methods
(BIO-ENV). Total 22 macrophyte species were recorded belonging to Chlorophyta,
Phaeophyta and Rhodophyta. The macrophyte communities dominated by Dictyota sp. and
Sargassum sp. The macrobenthos were represented by overall 47 taxa. The macrobenthos
abundance were dominated by Crustacea, Polychaeta and followed by Mollusca. Spearman
rank correlation (using BIO-ENV procedure included in PRIMER, V.6) showed significant
correlation between macrobenthic diversity and type of macrophyte variables with highest
correlation (r=0.606) particularly Rhodophyta community. This study suggests that major
environmental factor of Rhodophyta species enhances the macrobenthic species diversity in
the central west coast of India.
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EFFECT OF UPWELLING-DRIVEN HYPOXIA ON MACROBENTHIC COMMUNITY
OF SOUTH WEST COAST OF INDIA
Sanitha K. Sivadas1*, G.V.M. Gupta2, BS Ingole1
1
2
Centre for Marine Living Resources, Kochi, India
Global warming and anthropogenic activities is increasing the areas and depth of low
oxygen waters in the marine system. The sediments off Kochi are one of the most
productive upwelling regions along the west coast of India (eastern Arabian Sea). High
productivity along the west coast of India is observed during the upwelling period during the
monsoon season. The high productivity in the water column increases the organic matter
flux to the benthic system which reduces the bottom water oxygen. The focus of the present
work was to study the response of macrobenthic community (abundance, biomass,
functional diversity) to seasonal hypoxia. For the present study, six stations (14, 20, 31, 41,
50 and 102m) along a transect (997N 7604E to 997N 7564E) were sampled from
March to December 2012. Water samples were collected for physico-chemical parameters.
Sediment samples were collected using van Veen grab. Statistical analyses were carried out
using PRIMER 6 and Statistica 10. Principal Component analysis (PCA) revealed low oxygen
and high nutrients during May-July indicating upwelling in the study area. In general,
macrofaunal abundance and biomass was high at shallow depth (depth 14-31 m) while
species diversity was high at intermediate depth (41-50m). Abundance and biomass at the
shallow depths were highest during the low oxygen period (June-July). Further, the species
composition also showed a variation with the shallow stations completely dominated by
two polychaete species, Magelona sp. and Paraprionospio sp. The deeper stations (41-102
m) were dominated by Paraprionopsio sp., Monticellana sp, Neomediomastus sp.
Nemertenia and Amphipoda. The spatio-temporal variability of the macrofaunal community
was confirmed by the SIMPROF cluster and SIMPER analysis. Functional traits also showed
differences along the transect and seasonally. The community during hypoxia period was
dominated by deposit feeders while carnivorous species dominated after the monsoon
(October-December). Similarly, the deposit feeders dominated at shallow depths while the
density of carnivorous increased with deeper water depth. BIOENV analysis indicates that
the macrofaunal community (abundance, biomass and feeding guilds) showed significant
positive relation with bottom water chlorophyll and phaeopigment. Our study shows that
the variation in physico-chemical parameters and food availability interact and influence the
macrobenthic community in seasonally hypoxic coastal habitat.
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MARINE MICROALGA TETRASPORA SP: ABUNDANCE, NUTRIENT
AVAILABILITY AND INDICATION OF INTRACELLULAR LIPID AT VERAVAL
FISHING HARBOUR, GUJARAT, INDIA
A. B. Fulke*, M. Dey, A. Ram, R. Hardikar and S.N. Gajbhiye
CSIR- National Institute of Oceanography (CSIR-NIO), Regional Centre, Mumbai-400053; [email protected]
Globally, microalgae are being explored as a potential high-yield feedstock for
bioprospection. The key focus of bioprospecting for microalga Tetraspora sp.
(Chlorophyceae; average cell diameter 6-9µm) is to identify unique high intracellular lipids
producing marine microalgae from west Veraval fishing harbour of Gujarat, India as is most
abundant at nearshore stations from almost half decade. This study also appraises the
Tetraspora species abundance, nutrient availability in the region and recent importance of
this species are discussed.
Water samples for physicochemical parameters and phytoplankton were taken
seasonally from three different nearshore stations (V1, V1A, V2) at Veraval. Salinity was
determined by argentometric method, dissolved oxygen by winkler’s method and nutrients
(DIP, DIN, Silicate) by standard spectophotometric methods (Grasshoff et al. 1983).
Phytoplankton sample were collected in 500 ml of bottles by Niskin’s sampler and was fixed
with 2% Lugol's iodine. For enumerating and speciation of phytoplankton sub-samples (100
ml) were enumerated under a microscope (40X magnification). For further confirmation of
species samples has been analysed in 100 x magnifications (Olympus BX 53F) as well as in
analytical research SEM (Zeiss, EVO 18) (Fig.1). We have used concentrated samples rich
with Tetraspora cells for nile red (NR) staining(Fulke et al., 2010) and were analyzed for
intracellular lipids content in the Tetraspora cells by fluorescence Floid™ Cell Imaging
Station (Fig.1). Tetraspora sp. is contributing almost 90% of the total phytoplankton
population at Veraval stations (Fig. 2).
Fig. 1 Tetraspora sp. from water samples preserved in Lugol’s iodine: a-f Cells and colony of
Tetraspora sp. [pictures taken in Olympus BX53F (a-b) bright field, 100x; (c-d) DIC, 100x; (d)
Analytical SEM, Zeiss EVO 18, (e, f) cells expressing Nile red fluorescence for intracellular
lipid droplets examined with a FLoid™ Cell Imaging Station (Life Technologies, France)+.
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2500
2000
1500
1000
500
0
V2
V1
Total
Total
Total
Total
V1A
Total
Population (cells/L x 105)
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Fig. 2: Decadal distribution of Tetraspora sp. and total phytoplankton population at 3
selected station in Veraval
Increasing trend was observed for the total number of Tetraspora population. During
2014 maximum average population (670 × 105 cells/L) was recorded from Veraval.
Spearman rank correlation (r) and stepwise regression were used to evaluate the relation
between environmental variable and both Tetraspora population with Statistica 7.0 and
MINITAB version 13 package. Results showed only strong positive correlation with dissolved
nitrate (r=0.417, p<0.007). Regressional equation with other parameters [Tetraspora
population (No/L) = -1.25E+08 - 854465 Salinity - 1611635 DO + 6469986 Tw + 4254499 NO2
+ 589319 NO3 - 123184 NH4 - 210383 PO4 + 1630458 SiO4] can only explain the variability of
56%. Present study discussed about the effect of various physico-chemical factors and their
interactions on natural growth of Tetraspora sp at Veraval. Further, it also explores the
enhanced understanding of the effect of nutrient availability on algae cell division and
cellular composition like lipid. Henceforth, marine Tetraspora sp. biomass may be
remarkable model strain for the commercial utilities like nutraceuticals products, biofuel
and other value added products in future.
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ARE BORING SPONGES AN INCREASING THREAT FOR CORAL GROWTH IN
MALVAN MARINE SANCTUARY?
Sambhaji Mote1, Kalyan De1, Vishal Patil1, Perisamy R1, Rahul Nagesh1, Sabyasachi Sautya2,
Baban S. Ingole1*
1
2
CSIR-National Institute of Oceanography, Regional Centre, Mumbai
Coral reefs are familiar to us for their impressive biodiversity, productivity and scenic
beauty. Coral reefs are undergoing global decline due to numerous stress factors including
climate-change related temperature anomalies, suspended sediments and various
anthropogenic activity for coastal development that can detrimentally impact on coral
health. Apart from this abundance of boring organisms are suggested to be a direct
consequence of coral mortality. Clionoid (class Demospongiae, phylum Porifera) is one of
major important siliceous sponges known to be bore into calcareous material/ substrata.
Since Coral colonies and reefs form as calcareous skeletons, it is suggested that coral reefs
are heavily invaded by boring sponges, which are playing a significant role to destruction of
their physical structure. The boring sponge Cliona sp. is known to get overpower to the
stressed coral which they overgrow at a fast rate.
In India, coral reefs are distributed in six regions viz. Gulf of Kutch, Lakshadweep, Gulf
of Mannar, Palk Bay, Andaman and Nicobar Islands and the recently identified reefs of
Sindhudurga coast in Maharashtra State. The Malvan Sanctuary (MMS) is one of the marine
protected areas in India located in Sindhudurga District, Maharashtra State, Central West
coast of India. There are few studies have been conducted to find out the boring sponge
threats in Indian coral reefs. Hence we aimed to find the boring sponges and their effect on
corals during our survey in Malvan sanctuary. We conducted underwater survey by SCUBA
diving and snorkeling at 5 different locations in the Sanctuary in November 2014. The Belt
Intercept Transect (BIT) survey method was used to study sponges and associated corals.
Sponges were collected from each transect to identify coral sponge encrust. Sponges were
identified using standard techniques such as spicule preparation by acid digestion and
followed by scanning electron microscopy. Our result suggests Corals are currently invaded
by boring sponges (2 species); being the coral reef framework the substrate most invaded
followed by the rubbles and the living colonies. The results also indicated that boring
sponges are promoting the dislodgment of live colonies and large fragments from the
framework. The possible reasons are increased organic material and suspended material
promoting the growth of boring sponges. This is the first report on boring sponge invasion
to corals in Malvan Sanctuary.
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QUANTIFICATION OF PHYTOPLANKTON PHOTO-PHYSIOLOGICAL STATUS IN A
MONSOONAL ESTUARY
J. S. Patil*, A. C. Anil
CSIR–National Institute of Oceanography, Dona Paula, Goa 403 004; [email protected]
In vivo chlorophyll fluorescence induction and relaxation technique measures a suite
of photosynthetic parameters [initial, maximum and variable components of Photosystem II
(PSII) fluorescence, quantum efficiency of photochemistry, functional absorption crosssection and the kinetics of electron transfer on the acceptor side of PSII] that can be used to
assess the physiological status of the phytoplankton. Using this technique, phytoplankton
physiological responses to environmental conditions from Dona Paula Bay, west-coast of
India, was undertaken. This bay is influenced by distinctly higher runoff and rainfall during
south-west monsoon (June–September) compared to post-monsoon (October–January) and
pre-monsoon (January-May) season. Such a seasonality in the intensity of freshwater influx
influences abiotic and biotic factors. Phytoplankton, which are heterogenous in form and
function and also forming a basic link in aquatic food-web, are influenced by such
environmental changes. In this study phytoplankton physiological responses were observed
every day from October 2008 – May 2010 by quantifying chlorophyll, PSII parameters and
environmental conditions at a fixed station in the bay. Results pointed out that the
occurrences of chlorophyll peaks are more during monsoon (5 nos.) followed by postmonsoon (2-3 nos.) and pre-monsoon (1 no.). A good agreement between the chlorophyll
and variable fluorescence measurements for each season was established. Variable
fluorescence, quantum efficiency and functional absorption cross-section ranged up to 279
(relative units), 0.2 to 0.58 (dimensionless) and 178 to 511 Å2 quanta–1 respectively. The
high and low values for all the parameters observed during monsoon were due to the
changes brought in by the variations in the magnitude of freshwater influx. The variations
in species composition and their physiological status could be the other factors influencing
the PSII parameters round the year. An overview of these findings will be discussed and
presented.
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SPATIO-TEMPORAL VARIATION IN ASSOCIATED FAUNA OF THE SPONGE
CINACHYRELLA CAVERNOSA
A. Singh1, D.V. Desai1, N. L. Thakur1*
1
CSIR -National Institute of Oceanography, Dona Paula, Goa 403 004; [email protected]
Sponges belong to the phylum porifera serve as habitats for various other fauna.
Sponges are soft-bodied organisms having a network of inner channels forming the
aquiferous system, which supports variety of organisms (crustacean, molluscs, echinoderms,
protists, foraminifera etc.; Ribeiro et al. 2003, Neves and Omena 2004, Gaino et al. 2004,
Henkel and Pawlik 2005, Mazzoli-Dias et al. 2007, Schejter et al. 2012).
This paper describes the temporal variation in abundance and diversity of associated
fauna of the low intertidal sponge Cinachyrella cavernosa, collected from two different
geographical regions: Mhapan, Maharashtra (15°55’27.48” N; 73°33’29.89” E) and Anjuna,
Goa (15°34'34.99" N; 73°44' 23.89" E) on the central west coast of India.
A total of 23 annelid species, 7 species of arthropods, 2 species of molluscs and a
species of coelentrata were found living inside C. cavernosa. Among them, Syllis sp.,
Exogone sp., Neries sp. and species belonging to family sabellidae and terebellidae of
Annelida were the most frequent species found inside the sponges from both the locations.
Several species of annelids (Syllis sp., Neries sp. and other species belonging to family
phyllodocidae sabellidae, terebellidae, cossuridae, pisionidae, ampharetidae) and
arthropods (species of family penaidae and class insecta) were found in various ontogenetic
stages, which is suggestive of their commensalism type of association with the host sponge.
The sponge (C. carvernosa) collected from two different locations showed significant
difference in the diversity and abundance of associated fauna (p < 0.05). The diversity and
abundance of sponge associated fauna was found to be higher in pre-monsoon months
(March-April). The experiments in order to understand the role of sponge secondary
metabolites in regulating the sponge-associated fauna are underway.
References:
Gaino, E., Lancioni, T., La, Porta G., Todini, B. (2004), The consortium of the sponge
Ephydatia flviatilis (L.) living on the common reed Phragmites australis in Lake Piediluco
(central Italy),Hydrobiologia, 520(1-3), 165-178.
Henkel, T.P., & Pawlik, J.R. (2005), Habitat use by sponge-dwelling brittlestars, Marine
Biology, 146(2), 301-313.
Mazzoli-Dias, M., Ribeiro, S. M., & Oliveira-Silva, P. (2007), Foraminifera associated to the
sponge Mycale microsigmatosa in Rio de Janeiro State, south eastern Brazil: An initial
approach, Porifera Research: Biodiversity, Innovation and Sustainability: Série Livros, 28,
439-442.
Neves, G., Omena, E.P. (2003), Influence of sponge morphology on the composition of the
polychaete associated fauna from Rocas Atoll, northeast Brazil, Coral Reefs, 22, 123-129.
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Ribeiro, S.M., Omena, E.P., Muricy, G. (2003), Macrofauna associated to Mycale
microsigmatosa (Porifera, Demospongiae) in Rio de Janeiro State, SE Brazil, Estuar Coast
Shelf Sci 57, 1-9.
Schejter, L., Chiesa, I.L., Doti, B.L., & Bremec, C. (2012), Mycale (Aegogropila) magellanica
(Porifera: Demospongiae) in the south western Atlantic Ocean: endobiotic fauna and new
distributional information, Scientia Marina, 76(4), 753-761.
264
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RESPONSES OF PICOPHYTOPLANKTON COMMUNITY TO ENVIRONMENTAL
CONDITIONS IN DIFFERENT ECOSYSTEMS
S. Mitbavkar*, A. C. Anil
Picophytoplankton (PP) are the smallest primary producers which form an important
component of the phytoplankton community in estuarine, coastal and oceanic ecosystems,
encompassing freshwater, brackish water, sea water and hypersaline waters. They also form
important components of the marine biofilms. PP comprises two groups of cyanobacteria
i.e., Prochlorococcus (PRO) and Synechococcus (SYN) and one group of eukaryotes i.e.,
picoeukaryotes (PEUK). While PRO is known to occur only in open ocean waters, SYN and
PEUK are dominant in the coastal waters. Samples were collected from various ecosystems
around India for enumeration of the PP community structure, distribution and abundance
with respect to the environmental conditions. The PP community structure exhibited spatial
and temporal variations depending on the prevailing environmental factors. In the estuarine
waters, salinity gradients played an important role in the PP community structure wherein
two groups of SYN were observed, one with phycoerythrin pigment (SYN-PE) dominant in
the high saline waters downstream and the other with phycocyanin pigment (SYN-PC)
dominant in the brackish and freshwater upstream. In hypersaline ecosystem (salinity > 35),
SYN-PE was dominant followed by the PEUK whereas in freshwater ecosystems, SYN-PC was
dominant. In the open ocean waters of the Arabian Sea and the Bay of Bengal, SYN, PRO and
PEUK were observed, with SYN and PRO as dominant groups whereas in the coastal waters
only SYN and PEUK were observed. PP distribution is also influenced by the physical forcing
such as tides and freshwater influx in estuarine regions. These observations suggest that PP
community structure varies across the different ecosystems depending on the
environmental conditions.
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DISTRIBUTION OF CYST PRODUCING DINOFLAGELLATES FROM A MONSOON
INFLUENCED TROPICAL EUTROPHICATED ENVIRONMENT
R. V. Rodrigues*, J. S. Patil, K. Sathish, A. C. Anil
Several species of dinoflagellate are capable of toxin production and are important
from the harmful algal blooms (HABs) perspective worldwide. Most dinoflagellates produce
resting cysts as part of their life cycle or survival alternatives in adverse environmental
conditions and serve as seed bank. As a result, dinoflagellates are considered amongst the
most unwanted marine bioinvaders. In order to study the distribution of cyst producing
dinoflagellates in a given environment it is important to both vegetative forms (VF) and cyst
stages and such investigations are limited along the Indian coast. In this study the VF of the
cyst producing dinoflagellates from water column and cyst from recent surface sediments
from a monsoon influenced eutrophic environment (Cochin port, south-west coast of India)
were investigated during post monsoons (October 2011 and November 2012), pre monsoon
(May 2012) and monsoon (August 2012). The abundance of VC varied from 89 to 2675 cells
L-1 and cysts from 89 to 1721 cysts g-1 dry sediment. High cyst and VF abundance were
observed during post-monsoon under high saline and low nutrient conditions whereas low
abundance were observed during monsoon under low saline and high nutrient conditions.
In the water column a total of 52 species (29 phototrophic and 23 heterotrophic
forms) of planktonic dinoflagellates belonging to 21 genera, were recorded. Out of 52 only
18 species are known to form cysts and their contribution on an average was up to 52% of
total dinoflagellate abundance. In sediments, 35 species (18 phototrophic and 14
heterotrophic forms) of dinoflagellate cyst belonging to 14 genera were recorded. A
comparison of VF and cysts data from the region reveals the presence of 40 species of cyst
producing dinoflagellate. Of which only 13 species, with Pyrophacus steinii (phototropic) as
the dominant form, were found both in the VF and cyst stages. Phototrophic and
heterotrophic VF were dominant during non-monsoon and monsoon season, respectively.
Whereas in the case of cysts, phototrophic forms were dominant during post-monsoon and
monsoon, and the heterotrophic forms during pre-monsoon. Comparison with existing
reports along the west coast of India indicated that the study region harbours higher cyst
abundance. It has been observed that out of 61 cyst producing dinoflagellates only 19 were
reported all along the west coast. This also includes the species (Alexandrium cf tamarense,
Gonyaulax spinifera complex, Lingulodinium polyedrum, Protoceratium reticulatum,
Scrippsiella trochoidea) known for their potential for causing toxic/harmful algal blooms.
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BIODIVERSITY PATTERNS OF MEIOBENTHOS FROM THE INDIAN OCEAN
IVY PEREIRA, B. S. INGOLE*
CSIR-National Institute of Oceanography, Dona Paula, Goa- 403004; [email protected]
Organisms and biological communities differ in a highly regular pattern along
geographic gradients. Establishment of a database provides a scheme to aid in setting up
conservation priorities as Biodiversity-Hotspots, the key areas and also to minister to our
understanding the ecological and evolutionary processes in the sea. Based on the size of the
juvenile stage meiobenthic organisms can be divided into permanent and temporary
fauna.This review presents a distribution of permanent and temporary meiofaunal groups in
the Indian Ocean, and thereby aid to mark up the eco-regions and also broaden our
understanding of the biogeography of the dominant meiobenthic groups. We used the
species distribution data of the five groups- Nematoda and Harpacticoida- temporary fauna
and Gastrotricha, Gnathostomulida, Kinorhyncha, Loricifera and Tardigrada belong to the
permanent fauna. Two taxonomic distinctness indices (∆+ and λ+) were used to analyse the
diversity pattern. The jaccard and Theta cluster analysis was applied for the biogeographic
similarity. A total of 177 nematode species belonging to 108 genera and 38 families have
been recorded in this region. Most nematode species belonged to Desmodoridae (24
species) and the Xyalidae (21 species) family. 285 marine harpacticoid species belonging to
107 genera and 32 families have been recorded from the Indian Ocean. The family,
Miraciidae having the highest (54 species) number of species followed by the Laophontidae
(40 species). 10 families have been recorded in the Indian Ocean distributed over 103
gastrotrich species and 27 genera. The most speciose gastrotrich families are
Thaumastodermatidae (34 species) and Chaetonotidae (18 species). A total of 47 marine
tardigrade species belonging to 22 genera and 6 families have been recorded.
Halechiniscidae having the highest (31 species) number of species. Thirteen Kinorhyncha
species were distributed over 7 genera and 7 families. Echinoderidae had the maximum (5)
species. Few species of Ganthostomulida were documented. The species belonged to genus
Gnathostomula. Loricifera Rugiloricus renaudae sp. Nov is the only record in the Indian
Ocean till date. The results depict cosmopolitan behaviour by majority of the meiofaunal
groups despite the meiofauna dispersal paradox. The observed variation may be related to
ocean circulation patterns, seafloor topography and insufficient data. To the best of our
knowledge, the present study is the first to report the distribution pattern of dominant
meiofaunal groups in the Indian Ocean. An important output of the study is identification of
lacunae in the meiofaunal study from the Indian Ocean attributed to the scarcity of data.
This is largely due to the lack of studies conducted considering the permanent meiofaunal
groups.
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BACTERIOLOGICAL STUDY OF A COMMERCIAL AQUACULTURE POND OF
LITOPENAEUS VANNAMEI ALONG SOUTH WEST COAST, INDIA.
Elaine A. Sabu*, Maria Judith Gonsalves, Sreepada A. R, Naseera K., Archana Naik and
Ramaiah N.
Aquaculture contributes a major share for sustainable fisheries sector in India. In the
recent years, one of the traditionally cultivated shrimp species Penaeus monodon has been
replaced by the imported Litopenaeus vannamei due to their better resistance to disease
attack. The shrimp production rates, besides being dependent on the species of shrimp, is
also related to the pond preparation, maintenance, water and sediment quality,
commercially available probiotics, aeration etc. Bacteria – phytoplankton being part of the
pond ecosystem play a role in shrimp production rates. Since, baseline data is essential for
improving commercial pond management practices, a shrimp pond located near the
mangrove regions of south west coast of India was selected for a study on the
biogeochemical changes occurring during a production cycle.
Water and sediment samples were collected at regular intervals for the analysis of
physico chemical and biological parameters during the production cycle of Litopenaeus
vannamei. Estimation of ammonia, nitrite, nitrate, phosphate, dissolved oxygen, BOD5, total
suspended solids were performed based on APHA (2005). Chl a and phaeophytin pigments
were done following Parsons et al. (1984). Total organic carbon in sediment samples were
analysed following the modified Walkley and Black method (Page et al. 1982). Biochemical
analysis of the sediments was estimated following the procedures of Kochert (1978), Lowry
et al. (1951) and Bligh and Dyer (1959) respectively. Various bacterial groups associated with
the pond samples were enumerated using their respective media (Rodina, 1972).
In the pond used for this study the survival rates of the shrimps were 77.86% with an
average shrimp weight of 20.83g. In this pond water, the average ammonia level was 0.078
± 0.12µM, nitrite was 0.009 ± 0.12µM, nitrate was 0.212 ± 0.27µM and phosphate was
0.008 ± 0.004µM during the production cycle. These low levels of nitrogen may be due to
applied probiotics and the dynamic cycling by the phytoplankton, heterotrophic bacterial
population. The total heterotrophic bacterial plate counts in water were three orders lesser
than those of the sediments. The heterotrophic bacteria outnumbered the anaerobes,
sulphate reducing bacteria, nitrate reducers, sulfur oxidizing bacteria, methane oxidizing
bacteria, and denitrifying bacteria. Organic carbon mineralization by heterotrophic bacteria
(r=-0.748, p<0.05), (r=-0.703, p<0.05); sulphate reducers (r=-0.777, p<0.01), (r=-0.641;
p<0.05) and total anaerobes(r=-0.777, p<0.01), (r=-0.873, p<0.01) was evident by a
significant correlation of these groups with total organic carbon in water and sediment
respectively. The different bacterial groups were significantly related to pond parameters
indicating their role in driving pond dynamics. The above findings will provide the basis for
the development of more advanced, eco-friendly bioremediators which can also improve
harvest of shrimps with better nutritional standards for consumption.
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PICOPHYTOPLANKTON CONTRIBUTION TO THE PHYTOPLANKTON BIOMASS
IN A MONSOON INFLUENCED TROPICAL ESTUARY
K. M. Rajaneesh*, S. Mitbavkar, A. C. Anil
Picophytoplankton (PP; cell size < 3 µm) is an important group of the phytoplankton
community in terms of abundance and primary production in the marine environment.
Although this group dominates the phytoplankton community in the open oligotrophic
waters, its importance in the coastal waters is being recognized in recent years. However,
there is not much information available on PP community structure and its contribution to
the total phytoplankton biomass in the coastal regions of the Arabian Sea along the west
coast of India. In view of this, an investigation was carried out from October 2010 to
September 2011 along the salinity gradient (35 to 0) in the monsoon influenced Zuari
estuary, Goa. Four groups of PP were identified and quantified; (1) Synechococcus
containing phycoerythrin pigment (SYN-PE), (2) Synechococcus containing phycocyanin
pigment (SYN-PC), (3) picoeukaryotes, and (4) Prochlorococcus-like cells based on flow
cytometric analysis. PP biomass (< 3 µm) and phytoplankton biomass (> 3 µm) were
estimated from the pigment chlorophyll a (chl a). Zuari estuary exhibited wide variations in
environmental conditions which are attributed to fluctuations in rainfall during monsoon
season and tides during the non-monsoon seasons. This was reflected in monthly variations
of PP biomass and > 3 µm phytoplankton biomass. Annually, PP were a major component of
the total phytoplankton biomass, contributing up to 41% of the total chl a, with the highest
contribution during post-monsoon and lowest during monsoon season. PP biomass
contribution was higher upstream during the monsoon and post-monsoon and downstream
during the pre-monsoon season. Although lower in abundance, picoeukaryotes were the
major contributors to the total PP biomass during different seasons due to their larger cell
size. SYN-PE, the most abundant PP group contributed up to 90% to the total PP biomass at
the estuarine mouth. High PP biomass in the Zuari estuary suggests that PP plays an
important role in the food web dynamics of monsoonal estuaries in tropical regions.
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SALINITY INDUCED PHYTOPLANKTON DOMINANCE ALONG TAPI ESTUARINE
ECO- SYSTEM
Prince Prakash Jeba Kumar. J* , Ragumaran.S, Sundararajan.S, Karupasamy.M,
National Institute of Ocean Technology, Pallikaranai, Chennai-600100; [email protected]
A study was carried out to understand the seasonal variation of water quality and
phytoplankton diversity along the polluted stretch of Tapi river estuary for a period of one
year. Significant seasonal variation recorded among the 10 stations spread along the study
area. The phytoplankton were represented by Bascillariophyceae (60.1%), Dinophyceae
(0.7%), Cynophyceae (17%), Chlorophyceae (21.6%), Chrysophycea (0.1%) and
Xanthophyceae (0.5%). Among these organic pollution indicators like Skeletonema
costatum (9493 - 11040 Nos./L ) & Cycloptella sp. (4373- 19200 Nos./L )belongs to
Bascillariophyceae recorded typical dominance at non polluted station during premonsoon
season of the year 2003. Identified salinity inducted dominance rather than the influence of
organic content of the water body and supported by laboratory scale studies on
electrophoretic mobility of euryhaline phytoplankton.
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DIVERSITY AND COMMUNITY STRUCTURE OF MACROBENTHOS ALONG THE
SALINITY GRADIENT OF AN ANTHROPOGENICALLY STRESSED ESTUARY
J.T. Mulik, S. Sukumaran*, T.V. Vijapure, S.M. Salvi
CSIR-National Institute of Oceanography, Regional Centre Mumbai; [email protected]
Ulhas estuary, located on the west coast of India, is the recipient of uncontrolled
discharge of pollutants from both point and non-point sources (Ram et al; 2009).
Macrobenthic community structure combined with pertinent abiotic parameters were
investigated from 12 stations along the salinity gradient of the estuary. Four sediment
samples were collected for macrobenthos analyses using a van Veen grab of 0.04 m2 bite
area. The benthic organisms were sorted to major taxa (phylum, order or class),
enumerated and expressed as ind.m-2. At each station, bottom water samples were
collected in duplicate for analyzing various physico-chemical parameters. Salinity, SS, DO,
and nutrients were analyzed using standard methods (Grasshoff et al., 1999). PHc in water
was measured with a fluorescence spectrophotometer (LS 3B Perkin Elmer) (IOC-UNESCO,
1984). Corg was analyzed by titration method (Walkey and Black, 1934) and sediment texture
by combined sieving and pipette method (Buchanan, 1984).
Totally, 34 macrobenthic taxa were recorded. The dominant taxa, polychaetes (~73%),
were then identified upto lowest possible level (Day, 1967; Fauvel, 1953). Univariate indices
confirmed poor ecological health of the estuary especially in the mesohaline zone.
Macrobenthos was completely absent at stations 8 and 9 situated in the middle estuary.
This zone was characterized by high levels of nutrients and organic carbon coupled with low
dissolved oxygen indicating that the estuary was highly eutrophic here. Four distinct groups,
clearly segregated by the multi-dimensional scale (MDS) analyses (Fig 1A) indicated that
salinity was a major influencing parameter.
B
A
Figure 1: Non-metric multidimensional scaling ordination of fourth root transformed
macrobenthic abundance data (A) and abundance of Streblospio gynobranchiata
superimposed as bubbles (B).
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Macrofaunal abundance was highest (4700±4846 ind. m-2) in the middle zone and was
dominated by the opportunistic polychaete, Streblospio gynobranchiata (61.6%)(Fig 1B)
which was found to thrive in low oxygen conditions. Margalef’s richness index (d) correlated
positively with salinity. All univariate indices correlated negatively with organic carbon and
ammonia indicating anthropogenic impact on macrobenthic diversity. The BIO-ENV analyses
indicated the combined influence of salinity, NO2--N and NH4+-N on the distribution patterns
of macrobenthos of the Ulhas estuary (Table 1). Hence, it can be concluded that the
macrobenthos community structure was influenced both by natural (i.e. salinity) as well as
anthropogenic factors in tandem.
Table 1 : Results of BIO-ENV analyses. The variables marked in bold show the highest
correlation.
Spearman correlation()
No.
Variables
1
Salinity
2
Salinity, NO2--N
3
4
0.488
0.454
-
+
0.510
-
+
0.489
Salinity, NO2 -N, NH4 -N
Salinity, NO2 -N, NH4 -N, SS
References:
Buchanan, J.B., 1984. Sediment analysis. In: Methods for study of marine benthos (second
edition) Holme NA and McIntyre AD) Blackwell Scientific publications, Oxford and
Edinburgh, 1-65.
Day, J.H., 1967. A Monograph on the polychaete of southern Africa, Part I (Errantia) and Part
II (Sedentaria). Trustees of the British Museum, Natural History, London, pp. 1-878.
Fauvel, P., 1953. Annelida Polychaeta. The Fauna of India including Pakistan, Ceylon, Burma
and Malaya pp. 507.
Grasshoff, K., Ehrhardt, M., Kremling, K., 1999. Methods of seawater analysis (Verlag
Chemie), 1-419.
IOC-UNESCO., 1984. Manual for monitoring oil and dissolved dispersed petroleum
hydrocarbons in marine waters and on beaches. Manual and Guides No. 13, 1-35.
Ram, A., Rokade, M.A., Borole, D.V., Zingde, M.D., 2009. Diagenesis and Bioavailability of
mercury in the contaminated sediments of Ulhas Estuary, India. Marine Pollution Bulletin
58, 1685–1693.
Walkey, A., Black, I.A., 1934. An examination of the Degtjareff method for determining soil
organic matter and a proposed modification of the chromic acid titration method. Soil
Science 37, 28-30.
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MACROBENTHIC ASSEMBLAGES OF TWO MARINE PROTECTED AREAS ALONG
NORTHWEST COAST OF INDIA: DIVERSITY AND DISTRIBUTION
T.V. Vijapure, S. Sukumaran*, J.T. Mulik, V.R. Joshilkar, S. N. Gajbhiye
CSIR-National Institute of Oceanography, Regional Centre Mumbai; [email protected]
Malvan and Vadinar represent two coralline Marine Protected Areas (MPAs) along
north-west coast of India which are considered as biodiversity hotspots that are impacted
by different anthropogenic stressors. Vadinar coast is dotted by various oil and gas
industries whereas Malvan faces threats of unbridled tourism. The current study
investigated status of macrofaunal assemblages with associated hydro-sedimentological
data at four stations each at both areas during the critical season i.e. April-May 2013.
Sediment samples were collected in quadruplicate using a van Veen grab of 0.04 m 2
bite area. Benthic organisms were sorted up to higher taxa whereas polychaetes were
identified up to family level (Day, 1967; Fauchald, 1977).Feeding guilds of polychaetes were
determined as per Fauchald and Jumars (1979). Bottom water samples from each station
were analyzed for various physiochemical parameters. Salinity, SS, DO, and nutrients were
analysed using standard methods (Grasshoff et al., 1999). Sediment samples were studied
for sediment texture (Buchanan, 1984) and organic carbon (Walkey and Black, 1934).
Macrobenthic abundances were comparable (Fig.1) at Malvan (1638±1498 ind.m -2)
and Vadinar (1543±1676 ind.m-2). Polychaeta was the dominant taxon at both study areas
(>65%) and was represented by 27 families in all. Observations on the trophic guilds
indicated that the proportion of deposit feeders was more in Malvan whereas omnivores
were higher in Vadinar stations (Fig.2).
Fig.1: Macrobenthic and polychaete abundances (error bars represent standard deviation)
Fig.2: Distribution (%) of polychaete feeding guilds
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1.0
M4
Corg
Para
DO
Depth
Silt
Clay
M3
M2
Gly
Cap
Cos
Lum
Mal
Nep
VD4
VD2
VD1
Mag
Pil
Syl
VD3
Spi
Ter
Cir
Orb
Eun
Oph
M1
Sand
Amp
Salinity
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Fig 3: Canonical correspondence analysis (CCA) ordination plot of 17 polychaete families, 8
stations,7 environmental variables. [Δ:Polychaete families; o:stations; →:environmental
variables]
ENV. VARIABLES
SAMPLES
Univariate indices indicated healthy ecological status of both the ecosensitive zones.
One way ANOVA indicated that the Shannon’s diversity index at Vadinar *H’(log 2)=3.1±0.2]
was higher than that at Malvan *H’(log2)=2.6±0.1]. Possible reasons could be the restricted
access to Vadinar MNPS as compared to the unregulated tourism activities at Malvan. CCA
analysis (Fig.3) revealed salinity and sediment texture were major responsible factors for
distribution of annelid polychaete fauna.
REFERENCES
Buchanan, J.B., 1984. Sediment analysis. In: Methods for study of marine benthos (second
edition) Holme NA and Mc Intyre AD) Blackwell Scientific publications, Oxford and
Edinburgh, pp. 1-65.
Day, J.H., 1967. A monograph on the polychaete of southern Africa, Part I (Errantia) and Part
II (Sedentaria). Trustees of the British Museum, Natural History, London, pp. 1-878.
Fauchald, K., 1977. The polychaetes worms, definitions and keys to the orders, families and
genera. Natural History Museum of Los Angeles County Science Series 28, pp. 1-190.
Fauchald, K., Jumars, P.A., 1979. The diet of worms: a study of polychaete feeding guilds.
Oceanography and Marine Biology: an Annual Review 17, pp. 193-284.
Grasshoff, K., Ehrhardt, M., Kremling, K., 1999. Methods of seawater analysis (Verlag
Chemie), pp. 1-419.
Walkey, A., Black, I.A., 1934. An examination of the Degtjareff method for determining soil
organic matter and a proposed modification of the chromic acid titration method. Soil
Science 37, 28-30.
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STUDY OF MACROBENTHIC ASSEMBLAGES ON SUBTIDAL NEARSHORE
WATERS IN THE VICINITY OF ADANI POWER LTD MUNDRA, GUJARAT, INDIA
Santosh Kumar Singh, Anil Soni and Shivanagouda N. Sanagoudra*
Adani Power Ltd, Mundra, Gujarat; [email protected]
Spatial variation in the abundance of macrobenthic assemblages on subtidal costal
zone is known to be related to different environmental variables. Seasonal of the studies
have observed that along the costal gradient, Temperature and salinity is the most
important environmental variable driving the patterns of the macrobenthic population and
biomass assemblages. However, the great majority of studies have been done on Gulf of
Kutch, systems in nearshore regions. Our study investigated the relationship between the
macrobenthic assemblages in subtidal habitats and the environmental biotic and a-biotic
variables along three coastal nearshore zones of Intake, Outfall and offshore monitoring
controle sampling stations. From Intake to Outfall nearshore regions we sampled benthic
macrofauna, salinity and sediments. The structure of the benthic assemblages was primarily
related to salinity. There was a constant in the number of macrobenthic taxa from the
Intake to the outfall regions in APL, indicating there is no deviation from nearshore diversity.
There were important similarities of taxa abundance along different nearshore study
stations. Temperature and salinity gradients which can be properly tested in study regions.
Our study advocate that in order to adopt routine monitoring management practices it is
essential to identify broad patterns and general rules governing coastal nearshore systems.
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22-24 March 2015
SPATIAL VARIATION OF PHYTOPLANKTON PIGMENTS ALONG THE EASTERN
ARABIAN SEA DURING THE ONSET OF SOUTH WEST MONSOON
Ayaz Ahmed*, Chandrasekhara Rao, Siby Kurian, Manguesh Gauns, Amara BM, Bhagyashri
N, Hema Naik and S.W.A Naqvi
CSIR-National Institute of oceanography, Dona Paula Goa-403004; [email protected]
Arabian Sea experiences moderate to weak upwelling along the south west coast of
India starting from May-June which subsequently propagates towards the north. An attempt
was made to monitor the spatial variations in the distribution of phytoplankton groups
based on marker pigments using chromatographic technique (HPLC) supported with
microscopic and flow-cytometric analyses in the surface and sub-surface chlorophyll
maximum (Chlmax) layer along a transect parallel to the coast (8° to 18°N) and perpendicular
to the coast (off Trivandrum, TVM) in the eastern Arabian Sea during June, 2012. The depths
of sub-surface chlorophyll maximum varied in the range of 10 to 55m. About 15 marker
pigments (including fucoxanthin, peridinin, 19’-Hexanoyloxyfucoxanthin, 19’Butanoyloxyfucoxanthin, zeaxanthin, alloxanthin, divinyl chlorophyll a (Div-chl a) etc.) were
characterized by HPLC corresponding to seven major groups of phytoplankton community
(diatoms, prasinophytes, chlorophytes, cryptophytes, chrysophytes, dinoflagellates and
cyanobacteria,) derived in chemotaxonomic software (CHEMTAX). The concentration of
total Chl a and fucoxanthin were higher (upto 5.2 and 2.4µg/l respectively) towards the
south west coast of India (off TVM) whereas Div-chl a, marker pigment of Prochlorococcus
sp. was present only in the northern stations. Pigment indices derived based on plankton
size showed dominance of picoplankton (fpico) (upto 70% in few stations) followed by
nanoplankton (fnano) along the northern stations. Contribution of microplankton (fmicro) was
comparatively higher in the southern region (30-45%). Flowcytometric analysis of the
picoplankton revealed two major types of cells (synechococcus and Prochlorococcus sp.)
with carbon biomass ranging from 0.31 to 18.28 x109 and 0 to 0.85x109 ngC/lit respectively
in the surface waters whereas the biomass ranged from 0.07 to 8.75x109 and 0 to 0.66x109
ngC/l respectively in the subsurface Chlmax. Abundance of synechococcus was higher
towards the southern stations, while prochlorococcus was dominating in the northern
region as evidenced by the marker pigment Div-chl a. Microscopic observation revealed the
dominance of two major groups; diatoms and dinoflagellates with overall species count of
23 and 29. Quantitatively the diatom cell number along the N-S transect varied from 1.24 to
7.13×103 cells/l in the surface waters and 0.31 to 10.66 ×103 cells/l in the Chlmax with higher
numbers towards the south. The cell numbers were much higher along the transect off
TVM, which varied from 0.76 to 556.5×103 (surface) and 1.656 to 336.7×103cells/l in the
Chlmax. CHEMTAX derived diatom contribution to the total chlorophyll a also showed higher
values towards the south west coast of India with highest concentration along the transect
off TVM (3.19µg/l in the surface and 2.78µg/l in the Chlmax). Our study clearly showed the
dominance of diatoms along the south west coast of India during the onset of upwelling
whereas the picoplankton dominance towards the north, which is evident from both
chromatographic and microscopic/flow cytometric studies.
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SEASONAL INFLUENCE ON METHANOTROPHIC ABUNDANCE, ITS ACTIVITY AND METHANE
PRODUCTION IN A TROPICAL MANGROVE ECOSYSTEM
Delcy R. Nazareth*, M-Judith Gonsalves
CSIR-National Institute of Oceanography, Dona Paula, Goa 403 004; [email protected]
Coastal regions are potential zones for production of methane governed by ecological/
environmental differences or even sediment properties. Mangroves, one of the most
productive coastal ecosystems, are characterized by high turnover rates of organic matter
and nutrient recycling between the ocean and terrestrial habitats. Mangroves harbour
highly reduced anaerobic sediments wherein, one of the processes that aid mineralization of
organic carbon is methanogenesis. The methane produced is oxidized by methanotrophic
bacteria. These potential biofilters quench the emission of this greenhouse gas and play a
vital role in the methane cycle that gets influenced by season. Hence a study was conducted
at a model site in a tropical mangrove region in Goa on the west coast of India to assess the
influence of season and environmental variables on methanotrophic abundance, its pattern
of distribution and its activity. Physico-chemical, sediment, biochemical and bacterial
parameters were estimated by standard procedures. The influence of environmental
variables on the abundance, production and activity was more marked during the monsoon
season. During the monsoon season the methanotrophs were an order higher
(1.02±0.47x105) than those during the pre-monsoon. This was corroborated by highest
methane production during the monsoons which was positively influenced by TOC (r=0.65;
p<0.001). Thus, indicating that methanogensis dominated the terminal pathway of organic
carbon mineralization. Lowest methanotrophs and low production and activity rates was
observed during the pre-monsoon season. This may be due to seasonal fluctuations which
may have lead to changes in the reserves of TOC and the limited methane supply during the
summer season. During the pre-monsoon, salinity influenced methane production (r= 0.81;
p<0.001) suggesting a co-existence of processes like sulphate reduction and
methanogenesis in the presence or absence of non-competitive substrates however, such
an influence was absent in the monsoon and post-monsoon seasons. Maximum
methanotrophic activity of 1.3x10-4cell-1hr-1 was during the post monsoon which was
influenced by TOC (r=0.59; p<0.05). Generally, methane production showed an increasing
trend with depth while methanotrophic population and its oxidation decreased with depth.
The high methane oxidation rates at the surface, is supported by the presence of a loose
organic layer at the surface of the sediment core. Depth wise variation, in these sediments
was driven by oxygen permeability and organic matter availability. In general, the
methanotropic abundance, its activity and methane production were governed by seasonal
influence as evident from the impact of different environmental variables during different
seasons.
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TEMPORAL AND SPATIAL VARIATION IN THE ZOOPLANKTON DISTRIBUTION
AND ABUNDANCE IN THE ZUARI ESTUARY, WEST COAST OF INDIA
Dattesh V Desai*, Dayakaran P, Monteiro MC, Anil, A.C.
CSIR-National Institute of Oceanography, Donapaula, Goa-403004; [email protected]
Zooplankton are the important component of the aquatic food chain. They are
heterotrophic animals and link the microbial food web to the classic food chain, and transfer
materials and energy from primary producers to higher tropical levels. They inhabit almost
all aquatic habitats ranging from fresh water to estuaries to open ocean. Estuaries are
dynamic environment where tidal mixing and fresh water input create large variations in
physico-chemical parameters which may affect plankton community composition. In the
present study temporal and spatial variability in major groups of zooplankton was studied in
the Zuari estuary during pre-monsoon, monsoon and post monsoon seasons at four stations
namely Dona Paula, Cortalim, Borim and Sanvordem representing the upstream, middle and
downstream region along the estuary. Besides zooplankton sampling, observations were
also made on the physico-chemical parameters such as temperature, salinity, dissolved
oxygen, suspended particulate matter and chlorophyll to examine their influence on
distribution and abundance of major zooplankton groups. The salinity varied from near
freshwater to 34psu in the estuary and the abundance and biomass of zooplankton was
lowest during low saline conditions. Spatially, zooplankton showed large variation in the
upper mid stations (Cortalim and Borim) and least in the downstream station (Dona Paula).
In Sanvordem, which is the upstream station, the biomass and abundance was lowest and
this can be attributed to very low salinity or near freshwater conditions. Among
zooplankton, calanoid copepods contributed maximum to the total abundance followed by
cyclopoid and harpecticoid copepods. Copepods were abundant at all salinity ranges
exhibiting wide tolerance. Meroplanktons were abundant during non-monsoon months and
their abundance coincided with high chlorophyll. The results indicated that changing
environment with seasons played an important role in the distribution and abundance of
zooplankton.
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VARIATION IN THE CULTURABLE VIBRIO CHOLERAE ABUNDANCE ALONG THE
COAST OF INDIA
Lidita Khandeparker*, Gardade L, Kuchi N, Eswaran R, Hede N, Mapari, K.E., Anil, A.C.
Vibrio cholerae has been identified as one of the important pathogenic bacteria that
could be translocated through ships’ ballast water from the waters along the subcontinent
of India. In view of this, under the Ballast Water Management Program – India (BAMPI),
quantification of culturable Vibrio cholerae from different port environments is underway.
In this paper, we present the overview of variations in the abundance of V. cholerae from
the ports of Mangalore and Kochi. The results from previous studies carried out at Goa and
Vishakhapatnam are taken for comparison. Water samples for the quantification of V.
cholerae were collected during different seasons viz., Pre-monsoon, Monsoon and Postmonsoon. V. cholerae are ubiquitous in aquatic environments but they are however known
to prefer fresh to brackish waters conditions. The observations in these localities showed
that the highest abundance was in the post-monsoon season in New Mangalore port (3.03 x
104 CFU ml-1) which is a coastal marine environment where as Kochi port, which is located
within the backwaters had highest abundance during the pre-monsoon season (3.67 x 103
CFU ml-1). Observations carried out in Vishakhapatnam and Goa point out high abundance
during the monsoon season. Such spatial variation point out that the ecosystem functioning
plays an important role in the dynamics of V. cholerae. In view of this, elucidating the
variations of V. cholerae population should include, in addition to the environmental factors,
the influence of planktonic population, organic matter and nutrient flux.
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DISTRIBUTION AND ABUNDANCE OF MACROBENTHOS FROM MANGALORE
PORT
Dattesh V Desai*, Atchuthan P, Noyel V, Anil, A.C.
Benthos are the bottom living communities which play an important role in aquatic
ecosystems, such as mixing of sediments, flux of oxygen into sediments and cycling of
nutrients and also important in secondary production. Invasion of aquatic organisms
through ships' ballast water is considered as a major threat to the biodiversity of world's
oceans. During the port biological baseline survey for Ballast Water Management Program,
a study was conducted to understand the abundance and community pattern of soft bottom
macrobenthic organisms over different seasons in and around Mangalore port. The
macrobenthic biomass was maximum during pre-monsoon and minimum during postmonsoon season. It was observed that the higher biomass during pre-monsoon was
contributed by the occurrence of pelecypods (gastropods). The abundance was higher
during post monsoon, followed by pre-monsoon and monsoon season. Sand was the
dominant component of the sediment followed by silt and clay, however, their percentage
varied seasonally. Contribution of macrobenthic polychaetes was maximum to the total
abundance followed by amphipods and molluscs. The organic carbon which is an important
indicator of benthic conditions was higher during post-monsoon season, which is also
coincided with higher abundance of macrobenthic organisms.
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RESPONSE OF VIBRIO SPP. TO VARIATIONS IN SALINITY AND TEMPERATURE:
ELUCIDATION THROUGH PROTEIN PROFILING
Lidita Khandeparker*, Barnes N, Anil, A.C.
Estuaries are considered as environmental hotspots owing to increased anthropogenic
pressures and are known for their rich biodiversity. The interactions between biotic and
abiotic factors in this unique environment provide the opportunity to study the response of
organisms to various perturbations. We explored spatio temporal variations in the Vibrio
spp. (Vibrio cholerae, Vibrio parahaemolyticus, Vibrio alginolyticus) along the transect from
the mouth to the head of the Zuari estuary. Microcosm experiments were conducted to
evaluate the influence of changes in salinity and temperature on their viability. Response of
Vibrio spp. differed with salinity and temperature. V. alginolyticus could survive under
varying conditions of salinity and temperature to a greater extent than V. cholerae and V.
parahaemolyticus. The protein profiles of bacteria evaluated using MALDI-TOF Mass
Spectrometry revealed intraspecies variations.
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MOLECULAR DIVERSITY OF CHROMOPHYTIC PHYTOPLANKTON
ASSEMBLAGES FROM SUNDARBANS MANGROVE ECOREGION BASED ON
RBCL GENE SEQUENCING
Brajogopal Samanta and Punyasloke Bhadury*
Indian Institute of Science Education and Research Kolkata, Mohanpur-741246, Nadia, West Bengal;
[email protected]
The Sundarbans represent the world largest contiguous mangrove ecosystem located at northwest of the Bay of Bengal, encompasses over 102 islands with a network of innumerable rivers,
rivulets, and creeks. This vast deltaic region is formed at the estuarine phase of the GangesBrahmaputra and Meghna river system across India and Bangladesh. Phytoplankton is the important
constituent of aquatic primary production in Sundarbans wetlands. The phylogeny and diversity based
on the amplification and sequencing of rbcL, the large subunit encoding the key enzyme RuBisCO
was investigated coupled with traditional microscopy for improved understanding of the community
structure and temporal trends of chromophytic phytoplankton assemblages in the Indian part of
Sundarbans. Diatoms (Bacillariophyceae) were by far the most frequently detected group in clone
libraries as also based on microscopy, consistent with their importance as a major bloom-forming
group. Other major chromophytic algal groups including Cryptophyceae, Haptophyceae,
Pelagophyceae, Eustigmatophyceae and Raphidophyceae which are important component of
assemblages were detected for the first time from Sundarbans based on rbcL approach, but not using
microscopy. Many of the sequences from Sundarbans rbcL clone libraries showed identity with key
bloom forming diatom genus such as Thalassiosira Cleve and also confirmed by microscopic
observations. Principal coordinates analysis showed temporal pattern of OTUs distribution across the
study area as also confirmed by other statistical approaches. Additionally, using cultured approach, a
new species of diatom, Thalassiosira sundarbana was isolated and described from the study area and
this species was found to constitute an important component of the chromophytic phytoplankton
assemblages in Sundarbans. This study applied molecular and microscopic tools to delineate
chromophytic phytoplankton assemblages in Indian part Sundarbans ecoregion.
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INFLUENCE OF UPWELLING ON THE DISTRIBUTION OF BACTERIA AND
ARCHAEA IN PERSISTENT MUDBANK REGIONS OF ALLEPPEY, SOUTHWEST
COAST OF INDIA
Appukuttan V. Sheeba, Saumya Nair, Diana Mathew, Gireesh TR, Abdulaziz Anas*
CSIR- National Institute of Oceanography, Regional Centre Kochi; [email protected]
Mudbanks, a unique feature that appears along the southwest coast of India during
southwest monsoon season, are characterized by calm water even during very rough
monsoon, turbid seawater and copious fish catch [Gopinathan and Qasim, 1974]. Mudbanks
are reported to form during or immediately after southwest monsoon [Varma and Kurup,
1969]. Mudbanks in coastal waters of Kerala are classified as persistent or non-persistent
based on their activity and sustenance. The mudbanks of Alleppey activated during
monsoon are probably sustained throughout the year with decreasing intensity [Narayana
et al., 2008]. The complexity of mudbank formation and its unique water quality has always
attracted the researchers. However, the response of microorganisms to these
environmental changes is hitherto not studied. In the present study, we monitored the
influence of upwelling on distribution of bacteria and archaea in mudbank regions of
Alleppey for six months (April to September 2014).
Water samples were collected from three stations M1 (average depth 5 m), M2
(average depth 5 m) and M3 (average depth 11 m) at different depths at subsurface, 3 m, 5
m, 9 m and 11 m using a 5L capacity Niskin water sampler. (Fig. 1). Stations M2 was
designated as persistent mudbank region based on previous report, while M1 and M3 were
the controls for coastal and oceanic. The nutrient characteristics of water were analyzed
following standard protocols [Grasshoff et al., 1983]. Abundance of eubacteria and archaea
was determined using fluorescent in situ hybridization (FISH) technique. There was no
significant spatial and temporal difference in the abundance of eubacteria. In accordance
with the development of hypoxic conditions, there was an enhancement in the archaeal
abundance at the two coastal stations (M1 and M2), while such an increase was not evident
at M3 (Fig. 2). An increase in archaeal distribution from coastal to oceanic region was
reported earlier [Karner et al., 2001; Massana et al., 2000]. Here we observed increased
abundance of archaea in coastal regions during mudbank and this may be associated with
upwelling, which could transport archaea from oceanic to coastal waters. In short, the
present study shows that the upwelling has a strong influence on the distribution of
eubacteria and archaea in the mudbank region of Alleppey.
References:
Gopinathan, C. K. & Qasim, S. Z. (1974). Mud Banks of Kerala- Their formation &
Characteristics. Indian Journal of Marine Sciences 3, 105 - 114.
Grasshoff, K., Ehrhardt, M. & Kremling, K. (1983). Methods of seawater analyses. Verlag
Chemie. Weinheim, Germany 511, 342-355.
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Karner, M. B., DeLong, E. F. & Karl, D. M. (2001). Archaeal dominance in the mesopelagic
zone of the Pacific Ocean. Letters to Nature 409, 507 - 510.
Massana, R., DeLong, E. F. & Pederos-Alio, C. (2000). A few cosmopolitan phytotypes
dominate planktonic archaeal assemblages in widely different oceanic provinces. Applied
and Environmental Microbiology 66, 1777 - 1787.
Narayana, A. C., Jag, C. F., Manojkumar, P. & Tatavarti, R. (2008). Nearshore sediment
characteristics and formation of mudbanks along the Kerala coast, Southwest India.
Estuarine, Coastal and Shelf Science 78, 341 - 352.
Varma, P. U. & Kurup, P. G. (1969). Formation of the Chakara (mudbank) on the Kerala
coast. Current Science 38, 559 - 560.
Figure 1: Study area showing sampling locations.
Figure 2: Relative abundance of archaea compared to bacteria in stations M1, M2 and M3
during the study period
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RESPONSE OF PHYTOPLANKTON COMMUNITY TO MONSOON INDUCED
HYDROLOGICAL VARIATIONS IN THE ALLEPPEY MUDBANK REGION,
SOUTHWEST COAST OF INDIA
Madhu.N.V*, Ullas. N, Ashwini.R, Jyothibabu. R, Muraleedharan. K.R, Balachandran. K. K
CSIR-National Institute of Oceanography, Regional Centre, Kochi-18; [email protected]
Changes in the structural and functional properties of phytoplankton (biomass,
abundance and composition) in response to the upwelling was investigated in the coastal
waters of Alleppey, a region of recurring mud bank manifestations. The presence of cold
(<27°C), high saline (>34), oxygen deficient (<50µM) subsurface waters with high nitrateNO3-N (>4µM) and phosphate PO4-P (>1µM), perceived along the coastal waters (<15m
depth) off Alleppey apparently indicates the signatures of upwelling during the southwest
(SW) monsoon 2014. Prior to this period (April-May), the coastal waters were characterized
by dominance of nanophytoplankton (2-20µm), mainly belonging to pennate diatoms
(Thalassionema nitzschioids, Navicula directa, Pleurosigma normanii etc). During peak SW
monsoon period (July), there was a community shift as micro-phytoplankton (20-200µm)
formed the major contributors (>70%) of chlorophyll a. Multi-species proliferation of
diatoms (>20µm) such as Coscinodiscus radiatus, C. centralis, Biddulphia sp., Fragilaria
oceanica etc was in the response to the sudden increase in the availability of inorganic
nutrients (NO3-N and PO4-P) caused by the monsoon upwelling. Furthermore, Fragilaria
oceanica, a pennate diatom found to develop as a bloom (>200 x 10 3 cells L-1) over the
entire sampling area for one month period (July), till the signatures of strong upwelling
subsided. In September, with the weakening of upwelling, the water column became
vertically mixed, oxygen saturated, favouring simultaneous growth of both nano- and
microphytoplankton community. This short-term variability may certainly enforce critical
constraints for pelagic heterotrophs whose survival depend on nano-and microplankton
distribution in quality.
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22-24 March 2015
SULFUR OXIDIZING POTENTIAL IN THE MANGROVE CLAM POLYMESODA
EROSA
T.R.A. Thomas, P. A. Lokabharathi*
CSIR-National institute of Oceanography, Dona Paula, Goa; [email protected]
Mangrove swamps constitute one of the most productive ecosystems in the world.
The sediments here are rich in organic matter and diversity of species. Continuous
degradation of organic matter in these sediments leads to the formation of thick anaerobic
zones in the subsurface. Consequently infauna have evolved physiologically to counter the
effects of various reductants that keep accumulating. Polymesoda erosa is an exclusive
mangrove clam found towards the high tide region burying >70% of its body in the suboxic
to anoxic sediment. Therefore we probed the following questions. (1) Do these clams
possess sulfide oxidizing potential?. (2) Is this potential due to the bacterial associates?. (3)
What would be the their abundance and rate of activity?. (4) What are the major groups?. In
order to answer these questions we examined these clams from Chorao mangrove forest for
the abundance of associated bacteria in the gill, foot and mantle. Their rate of activity was
measured using a stable model compound such as thiosulfate both in the tissues and
ambient sediment
Thiosulfate utilization rate of gill, foot and
mantle of
P. erosa
Down-core profile of thiosulfate utilization rate
of sediment at different time interval
rate (µM/hr/g dry wt.)
-80
200
100
0
10
20
-200
30
Foot
Mantle
-300
-400
-40
-20
0
2
Gill
0
-100
-60
0
Depth (cm)
Rate (µM/hr/g dry wt.)
300
4
6
8
0 Min.
10 Min.
20 Min.
30 Min.
10
Time (Min.)
12
Figure 1: (a)Thiosulfate utilization rate of Polymesoda erosa (b) and the ambient sediment
[NB –ve values indicate utilization rate and +ve values release rate of thiosulfate]
Thiosulfate utilizing bacteria and activity were detected in all the tissues tested. The
observed activity were 5 to 20 times higher in tissues than the ambient sediment. Relatively
higher rate of thiosulfate uptake shown by gill (308 µM/hr/g dry wt.) (Figure 1a) could be
due to the retention of more sulfur oxidizers like cells (7.91x10 6) and thiosulfate oxidizing
bacteria (2.68x105) (Table 1). In the adjoining sediment maximum rate (80µM/hr/g dry wt.)
was observed at 6-8 cm depth (Figure 1b). Coccoid cells with a diameter ranging from 1 to 3
microns and rhodococcoid type cells were encountered in the gills. Though the identity of
culturable fraction is yet to be discerned, metagenomic data revealed the presence of
unculturable species belonging to the genus Marinobacter and the order Oceanospirillales.
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Unculturable coccoid bacteria belonging to these groups have known to perform
chemolithoautotrophy (Kuhn et al., 2014; DeLorenzo et al., 2012; Cao et al., 2014).
Autotrophic orders such as chromatiales and thiotrichales which are capable of sulfide
oxidation were also present (Thomas et al., 2014). Majority of the sequences belonged to γProteobacteria. On the contrary, in sediment, α-Proteobacteria dominated. Prevalence of
these thiosulfate oxidizing α-Proteobacteria have also been reported from other marine
sediments and hydrothermal vents (Teske et al., 2000). Though there was considerable
difference in the microbial community of the sediment and the gill, uncultured fraction of
certain bacterial group and Proteobacterial species were common. Their functions are yet
cryptic. Preliminary experiments on carbon fixation rates at the expense of thiosulfate
showed that the tissues were able to fix upto 1µM/hr/g dry wt. and sediment only about
0.2nM/hr/g dry wt.
Table 1. Range of Abundance of bacteria in gill, foot, mantle and sediment
Parameters
Gill
Foot
6
8
Mantle
Sediment (surface)
TC (/gm dry wt)
3.24x10 -1.45x10
1.56x10 -3.56x10
7
TVCa(/gm dry wt)
9.29x10 -1.22x10
5
7
4.01x10 -1.86x10
5
6
3.22x10 -2.91x10
6
7
3.56x10 -8.08x10
TVCan(/gm dry wt)
2.14x10 -3.66x10
6
7
1.80x10 -5.75x10
6
7
4.04x10 -1.60x10
6
7
3.15x10 -8.13x10
SO (/gm dry wt)
8.11x10 -1.50x10
5
7
0-3.69x10
MPN (/gm dry wt)
1.35x10 -4.00x10
5
5
7
6
5
1.45x10 -1.48x10
7
8
7.31x10 -1.35x10
9.67x10 -1.26x10
0-1.26x10
5
5
6
6
7
6
6
6
6
Not Present
5
1.24x10 -1.85x10
2
0.89x10 -6.81x102
TC: Total count; TVCa: Total viable aerobic count; TVCan: Total viable anaerobic count; SO: Sulfur oxidizers like coccoid cells; MPN: Most
probable number of thiosulfate oxidizers
The present study shows the thiosulfate utilization potential of the bacterial associates of
the mangrove clam P. erosa which reflects their role in sulfide oxidation. Since the bacterial
community in the gill, foot and mantle tissues are capable of thiosulfate utilization, they
could serve in the detoxification of sulfide in the ambient mangrove sediment. Both
sediment and tissue with their bacterial associates could potentially act as sink of CO 2 as
carbon fixation couples with thiosulfate oxidation.
References:
Kuhn, E. et al. (2014), Brine assemblages of ultrasmall microbial cells within the ice cover of
Lake Vida, Antarctica, Applied and environmental microbiology, 80, 3687–98.
DeLorenzo, S. et al. (2012), Ubiquitous dissolved inorganic carbon assimilation by marine
bacteria in the Pacific Northwest coastal ocean as determined by stable isotope probing,
PloS one, 7, e46695.
Cao, Y. et al. (2014), Novel psychropiezophilic Oceanospirillales species Profundimonas
piezophila gen. nov., sp. nov., isolated from the deep-sea environment of the Puerto Rico
trench, Applied and environmental microbiology, 80, 54–60.
Thomas, F. et al. (2014), Rhizosphere heterogeneity shapes abundance and activity of sulfur
oxidizing bacteria in vegetated salt marsh sediments, Frontiers in Microbiology, 5, 1-14.
Teske, A. et al. (2000), Diversity of Thiosulfate-Oxidizing Bacteria from Marine Sediments
and Hydrothermal Vents, Applied and environmental microbiology, 66, 3125.
287
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22-24 March 2015
MULTIPLE ANTIBIOTIC RESISTANCES AMONG VIBRIO CHOLERA ISOLATED
FROM COCHIN ESTUARY, SOUTHWEST COAST OF INDIA
Vijitha Vijayan1, Abdulaziz Anas1*, Sneha K.G1 , Anila Chandran1, Jasmin C1, Shanta Nair2
CSIR- National Institute of Oceanography Regional Centre, Cochin, Kerala 682018; [email protected]
CSIR- National Institute of Oceanography (NIO), Dona Paula, Goa 403004
Vibrios form an important group of microorganisms in marine environment owing to
their diverse ecological functions, ranging from participation in nutrient cycles to
metamorphosis of organisms. There are at least twelve Vibrio species known to be
pathogenic to human beings, amongst which V. cholerae remains the principal diarrhoeal
human pathogen. Notably, the last decade has witnessed a 50 % rise in the incidence of
cholera. In 2011 alone, WHO recorded 37 cholera outbreaks in 30 countries across the
world predominantly in Africa [WHO, 2012]. Health risks evoked by these organisms are
further aggravated by their multiple antibiotic resistances which make the therapy difficult.
Recent studies have proposed that these organisms have evolved from an oral-faecal
transmission linear model of a waterborne pathogen and human host, to a more complex
ecological model of an infectious disease due to the effect of anthropogenic climate
changes[Sedas, 2007]. This has become a grave environmental concern as it can influence
the human and environmental health adversely.
In the present study we report the antibiotic resistance profile and presence of
virulence genes in V. cholerae isolated from the Cochin estuary (CE) during the monsoon
and post monsoon seasons. V. cholerae was isolated on TCBS agar medium and the identity
was confirmed through fatty acid profile analysis. Antibiotic resistance profile was analyzed
in Mueller Hinton solid medium following standard disc diffusion (Kirby-Bauer) method.
Representative antibiotic discs belonging to inhibitors of cell wall synthesis (Ampicillin
25mcg and Vancomycin 10mcg), nucleic acid synthesis (Azithromycin 15mcg,
Chloramphenicol 15mcg, Gentamycin 30mcg, Oxytetracycline 30mcg and Tetracycline
10mcg), and protein synthesis (Ciprofloxacin 30mcg, Nitrofuratoin 100mcg, Nalidixic acid
25mcg and Trimethoprim 10mcg) were used. Multiple Antibiotic Resistance Index (MAR
index) was expressed as a ratio of number of antibiotics to which an isolate was resistant to
total number of antibiotics tested. The presences of toxigenic genes toxR in the isolates
were studied by standard PCR technique using gene specific primer. The comparison of fatty
profile of V. cholerae resistant to cell wall synthesis class of antibiotics with sensitive isolates
is also being reported.
The isolates were classified into low (MAR index < 0.25), medium (MAR index 0.25 –
0.5), high (MAR index 0.5 to 0.75) and extreme (MAR index 0.75 – 1.0) antibiotic resistant
based on their MAR index. Majority of the V. cholerae isolated from monsoon (63 %) and
post monsoon (56 %), showed high and medium (33 % of isolates from both monsoon and
post monsoon) levels of resistance against the antibiotics tested. A low level of antibiotic
resistance was observed among limited number of isolates. All the isolates showed
resistance against cell wall synthesis inhibiting glycopeptidase class of antibiotic,
Vancomycin, and 80 % were resistant against ampicillin belonging to β-lactamase class.
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More than 60 % of isolates from both seasons showed resistance against protein synthesis
inhibiting class of azithromycin and tetracyclin. Interestingly resistance against protein
synthesis inhibiting chloramphenicol was observed in less than 20 % of isolates. Resistance
against nucleic acid synthesis inhibiting antibiotics, Nalidixic acid and trimethoprim, was
observed among 20 % of isolates. Although there was no significant difference in the
composition of signatory fatty acid profile between V. cholerae isolates resistant and
sensitive to cell wall synthesis inhibiting antibiotics, we observed major changes in the
proportion of fatty acids such as 16:1 ω7c/16:1 ω 6c (Palmitoleic acid / palmitic acid )
followed by 18:1 ω 7c ( Cis- Vaccenic acid). PCR results showed that all the V. cholerae
isolates harbored toxR gene. Hence it is assumed that these isolates could be pathogenic to
humans and animals. In short the present study reports multiple antibiotic resistances
among V. cholerae isolated from CE. This may lead to a critical clinical dilemma, if the
environmental conditions favor the outbreak of cholera by these organisms. The broad
antibiotic resistance indicates that these organisms are of terrestrial origin and hence
further studies are necessary to understand the prevalence of multiple drug resistant V.
cholerae in CE and urgent control measures may be taken to prevent microbial pollution in
the estuary.
References:
1. WHO (2012) Weekly epidemological record. Geneva: World Health Organization. 31 - 32
31 - 32. 289 - 304 p.
2. Sedas VTP (2007) Influence of environmental factors on the presence of Vibrio cholerae in
the marine environment: a climate link. Journal of Infections in Developing Countries 1: 224
- 241.
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22-24 March 2015
DYNAMICS AND DISTRIBUTION OF BACTERIA AND VIRUS IN KRISHNA
GODAVARI BASIN, BAY OF BENGAL
Aswathy Vijaya Krishna, Anwesha Sarkar, Jasna Vijayan and Parvathi A*
CSIR-National Institute of Oceanography - Regional Centre, Kochi, 682018; [email protected]
Microbial dynamics, especially viral dynamics has been rarely investigated in the
Krishna-Godavari (KG) basin of Bay of Bengal. We report dynamic patterns of free living
viruses and heterotrophic bacteria in response to a variety of environmental parameters in
coastal and offshore waters of KG basin. All in all, we observed that there were marked
seasonal and vertical variations in abundances of bacteria and virus. Environmental factors
varied significantly with depth and distance from the shore that strongly influenced the
biological interactions between bacteria and virus. The culturable bacteria was mainly
constituted by Vibrio sp., Aeromonas sp., Staphylococcus sp., Corynebacterium sp.,
Streptococcus sp., Pseudomonas sp., and Neisseria sp. This poster gives a first insight on viral
and microbial ecology of KG basin during spring inter monsoon period.
290
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22-24 March 2015
MULTIPLE ANTIBIOTIC RESISTANT VIBRIO HARVEYI ISOLATED FROM PENAEUS
MONODON LARVAL REARING SYSTEMS OF SOUTH INDIA
Somnath S. Pai1,2, R. Preetha1,3, N.S. Jayaprakash 1,4, A. Anas1,5, I.S. Bright Singh1*
1
National Center for Aquatic Animal Health, Cochin University of Science & Technology, Fine Arts Avenue,
Kochi, 682016, Kerala, India; [email protected]
2
Current Address: Amity Institute of Virology & Immunology, Amity University, Sector 125, Noida, 201313,
Uttar Pradesh
3
Current Address: Department of Food Process Engineering, School of Bioengineering, SRM University,
Kattankulathur, 603203, Tamil Nadu
4
Current Address: Center for Bioseparation Technology, Vellore Institute of Technology, Vellore, 632014, Tamil
Nadu
5
Current Address: National Insitute of Oceanography, Regional Centre, Kochi, 682014, Kerala, India
Vibrio harveyi is a principal pathogen of shrimps in culture and antibiotics are used for
its control. The aim of this study was to assess the extent of antibiotic resistance in wild
strains of this bacterium isolated from shrimp larval rearing systems. Eighty seven strains of
V. harveyi of luminescent bacteria were isolated from rearing water, larvae and other points
of shrimp hatchery from two shrimp larval rearing units located in Kakinada, Andhra
Pradesh and one in Kochi, Kerala. Their sensitivity to 81 antibiotics encompassing various
classes was evaluated by disc-diffusion assay and their resistance profile was evaluated by
Multiple Antibiotic Resistance (MAR) index. The average MAR index for all isolates obtained
was 0.63 and they were highly resistant to antibiotics belonging to the classes -lactams,
macrolides, tetracyclines, sulfonamides, and quinolones/ fluoroquinolones. They were most
sensitive to aminoglycosides. The high MAR index of the isolates indicated that they were
being exposed to sub-lethal levels of antibiotics in shrimp hatcheries leading to the selection
of MAR strains of V. harveyi. The study shows that MAR variants of V. harveyi are dominant
in shrimp hatchery environment and are associated with larval mass mortality. This
information coupled with the ban on the use of certain antibiotics in shrimp culture,
considerably limits the choice of antibiotics for use against these organisms thereby
necessitating an urgent requirement of alternative therapeutics.
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MARINE BIOLOGY
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22-24 March 2015
ADENOSINE TRIPHOSPHATE IN THE WATERS OF WEST COAST OF INDIA-AN
INDICATOR OF LIVING MICROBIAL BIOMASS
Anindita Das1,2, Christabelle EGF-C1, Sheryl OF1, Sunita Pandey1 Dhillan Vellip1 and
LokaBharathi PA1*
1
CSIR- National Institute of Oceanography, Dona Paula, Goa-403004; [email protected]
2
Dass Scientific Research Laboratory Pvt. Ltd., Ahmedabad, Gujarat
The west coast of India is affected by various coastal forces like seasonal hypoxia and
anthropogenic inputs. Many parts are rich in placers and are targets of mining. Constant
changes in landscape are drastic and result in altering changing the activity patterns of
biota. These changes are even discernible at the microbial level Adenosine triphosphate
(ATP) is a biological energy currency and an excellent indicator of living and active microbial
biomass. The measurement of microbial ATP indicates the energy equivalent of all the living
microbiota in a given natural system. It is important in itself and in combination with other
microbial and biogeochemical parameters. We hypothesize that the distribution of ATP in
the waters of west coast of India could throw significant light on the seasonal layering
patterns and might relate to secondary or tertiary levels of production. In this paper we
report the ATP distribution in the coastal waters of Goa and Ratnagiri along the west coast
of India. The samples were collected and analysed from Sagar Sukti cruises SaSu138 (Goa,
April 2007), SaSu155 (Goa, October 2007), SaSu174 (Ratnagiri, May 2008) and SaSu176
(Goa, May 2008). Samplings were done at depths of 1, 5, 15, 25, 50 and 100m below sea
surface. Water samples (500ml) were filtered immediately on-board on 0.22µm white
cellulose nitrate filter papers. These filter papers were subjected to extraction in TRIS-HCl
buffer of pH 7.8 and stored at -15 to -20°C till analyses in the laboratory. The analysis of ATP
was done by luciferin-luciferase reaction in a BMG Optima Luminometer. The relative light
units (rlu) obtained were converted to equivalents of ATP expressed as ng l-1. ATP was
detected in all the samples and ranged from 103-104 ng l-1. Variations among depths were
arithmetical during October 2007 (post-monsoon) off Goa. They showed one order higher
value at deeper depths during April 2007(pre-monsoon) compared to October 2007 (postmonsoon). Higher ATP in deeper waters during pre-monsoon indicated higher live biomass
at relatively cooler sub-surface layers. It could also mean lack of predators at deeper depths
and/or sub-euphotic maxima of tertiary producers. Such stratifications were absent or
minimal in October 2007, post-monsoon. The annual variation from post-monsoon 2007 to
2008 was significant (p<0.05) in case of Goa. The values increased by an order in the year
2008. Ratnagiri and Goa did not differ significantly in 2008, and were in the same 10 4th order
in both cases. Thus pre-monsoons could be marked by higher microbial biomass and clear
layering in the distribution of ATP unlike the post-monsoon marked by a lower living
microbial load more homogenously distributed. This could be due to the seasonal
hypoxia/anoxia prevailing along the shelf during September-October. During a single season
there was no significant variation between Goa and Ratnagiri. Seasonal variations seem to
surpass annual variations. It is suggested that ATP could be an important parameter that
could be used not only as a direct indication of microbial biomass but also an indirect
indicator of potential tertiary production in different layers.
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ADVERTISEMENTS
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AUTHOR INDEX
ABHAY FULKE
ABHILASH S.
ABHISHEK NAGAR
ABHISHEK TAVVA
ACHYUTHAN H.
ADITI DESHPANDE
ADITYA PEKETI
AFREEN HUSSAIN
AHMED S. A.
AJAY YADAV
AKHIL P. S.
ALBERTINA DIAS
ALI M. M.
ALMEIDA ANSELMO
ALOK KUMAR MISHRA
AMARA B. M.
AMARENDRA P.
AMARNATH REDDY N.
AMEY DATYE
AMIT PRATAP
ANAND BABU AMERE
ANANDITA DAS
ANANT PAREKH
ANANYA KARMAKAR
ANAS A.
ANDHARE V.V.
ANDREW A MENEZES
ANIL A. C.
ANIL KUMAR
ANIL KUMAR K.
ANIL SONI
ANILA CHANDRAN
ANIRUDH RAM
ANJALI R.
ANJALY C. GOPI
ANJU S.
ANKIT GUPTA
ANOOP S. MAHAJAN
ANSHATH HUSSAIN
ANSHIKA SINGH
ANTONIO MASCARENHAS
ANUPAM KUMAR DIXIT
ANWESHA SARKAR
APARNA K.
APPUKUTTAN V. SHEEBA
AQLEEMA SHAH
ARAUJO J.
ARCHANA KAMBLE
ARCHANA N.
ARCHANA NAIK
ARINDAM SARKAR
ARULALAN T.
ARULMUTHIAH M.
ARVIND SAHAY
ARYA PAUL
ASHA USAPKAR
ASHALATHA K
ASHOK K.
ASHOKAN M.
ASHWINI KUMAR
ASHWINI R.
ASWATHY VIJAYA KRISHNA
ASWINI K. K.
ASWINI NAYAK
259
71
254
183
253
248
167
239
54
32
35
248
112
214
73
276
225
191
153
256
90
292
62
251
283
243
126
262
235
210
275
288
32
223
129
85
220
42
135
263
140
74
290
47
283
226
27
39
117
268
166
84
120
203
12
163
116
47
118
160
285
290
164
242
153
211
57
39
222
64
90
288
245
291
265
266
39
258
249
251
255
269
278
279
233
132
248
137
82
85
88
295
280
281
OSICON-15
22-24 March 2015
ATCHUTHAN P.
ATHIRA P. RATNAKARAN
ATMANAND M. A.
AUMONT O.
AYAZ AHMED
AZIZ-UR-RAHMAN SHAIK
BADESAB F. K.
BALACHANDRAN K. K.
BALAJI R.
BALAKRISHNAN NAIR T. M.
BARNES N.
BARPHE ANIKET
BASAVAIAH N.
BEHERA M. R.
BENJAMIN S.
BEPARI K. F.
BHAGYASHRI N.
BHANUMURTHY P.
BHARAT HARMALKAR
BHARATHI G.
BHASKARARAO DOKALA
BHAT U. G.
BHATT N. P.
BHATT N. Y.
BHAVANI T. S. D.
BHUPENDRA BAHADUR
SINGH
BINSIYA T. K.
BISHWAJIT CHAKRABORTY
BISWAPRAJNA MOHANTY
BOBADE K. B.
BOROLE D. V.
BRAHMANAND SAWANT
BRAJOGOPAL SAMANTA
BRIGHT SINGH I. S.
CARVALHO M. A.
CHAKRABORTY A.
CHAKRABORTY KUNAL
CHAKRABORTY S.
CHANDRASEKHARA RAO
CHARLS ANTONY
CHAUDHURI DIPANJAN
CHOUDHURY P. S.
CHOWDARY J. S.
CHRISTABELLE E. G. F. C.
DA SLIVA RHEANE
DAYAKARAN P.
D BANDYOPADHYAY
DELCY ROSY NAZARETH
DESAI D. V.
DEVIKA V. GHATGE
DEWANGAN P.
DEY M.
DHILLAN VELLIP
DHRUVA KUMAR PANDEY
DIANA MATHEW
DILEEP KUMAR M.
DIPTI RAUT
DRASTI GANDHI
ELAINE SABU
ELANGO S.
ESWARAN R.
ETHÉ C.
FEBY PAULOSE
FEMY PAULOSE
FERNANDES G. Q.
FERNANDES R.
280
52
120
23
38
19
157
285
134
225
279
87
163
226
174
27
276
225
115
90
22
247
63
146
222
48
52
126
242
193
155
167
282
291
165
3
12
153
276
231
67
145
62
292
169
278
13
277
263
115
163
259
292
71
283
10
242
146
268
120
281
23
113
113
215
217
275
163
229
233
31
222
225
186
127
58
60
64
89
17
19
278
280
90
96
252
185
296
OSICON-15
22-24 March 2015
FERNANDO V.
FOUSIYA A. A.
FOUSIYA T. S.
GAJANAN NAVELKAR
GAJBHIYE S. N.
GANESAN P.
GAONKAR M.
GAONKAR S. S.
GARDADE L.
GAUTHAM S.
GAWADE L.
GAYATRI VANI D.
GEETHA N.
GIBIES GEORGE
GIREESH T. R.
GIRISHKUMAR M. S.
GLEJIN JOHNSON
GNANASEELAN C.
GOKULAVASAN
GOPALA KRISHNA V. V.
GOPALA REDDY K.
GOPIKA S.
GOSWAMI B. N.
GOVIND RANADE
GOWTHAM D.
GOWTHAMAN R.
GUJAR A. R.
GUPTA G. V. M.
HAIMANTI BISWAS
HANI TALAMALA
HARDIKAR R.
HAREESH KUMAR P. V.
HARIKRISHNA SHARMA YG
HARIPRASAD P.
HARIS K.
HATKAR P.
HEDE N.
HEMA NAIK
HIMADRI TANAYA PANDA
HIMANSU K PRADHAN
ILANGOVAN D.
INDRAJEET GHOSH
INGOLE B. S.
IVY PEREIRA
IYER S. D.
JADHAV G. N.
JAGADEESH KADIYAM
JAGDALE S. P.
JANANI P.
JASMIN C.
JASNA VIJAYAN
JASTI CHOWDARY
JAYA KUMAR SEELAM
JAYAPRAKASH N. S.
JAYU NARVEKAR
JENA B. K.
JINEESH V. K.
JISHAD M.
JISMY POULSE
JITHIN ABRAHAM.K
JIYALAL RAM M. JAISWAR
JOSHI R. K.
JOSHILKAR V. R.
JOSSIA JOSEPH K.
JYOTHIBABU R.
JYOTI JADHAV
KAKATKAR R.
214
153
249
140
32
213
217
157
281
83
16
214
2
69
283
21
130
62
124
112
225
86
88
115
120
178
157
34
13
213
259
92
180
222
126
243
281
23
242
184
226
124
255
267
215
145
137
250
117
288
290
251
191
291
18
134
197
178
185
217
32
169
273
223
285
82
108
217
90
258
272
113
187
64
81
87
89
90
91
44
276
180
254
17
257
19
29
31
38
41
257
258
261
267
178
196
232
189
226
208
218
223
224
93
133
205
196
39
224
85
297
95
96
108
248
249
250
251
252
254
257
OSICON-15
22-24 March 2015
KALAVATI CHAGANTI
KALYAN DE
KAMALAKKANNAN K.
KAMANA YADAV
KAMESH RAJU K. A.
KANKONKAR A.
KANNAN R.
KAPIL MOHAN
KARISIDDAIAH S. M.
KARTHIKEYAN M.
KARUNAKAR KINTADA
KARUPASAMY M.
KHALAP S.
KIRAN A. S.
KIRAN GOVIND V
KIRAN GURUNG
KIRANMAYI S.
KRISHNA K. S.
KRISHNA M. S.
KRISHNAN R.
KUCHI N.
KUDALE M. D.
KULKARNI V. A.
KUMAR B. S. K.
KUMAR RAVI PRAKASH
KURIAN SIBY
KURIEN E. K.
LALLU K. R.
LATHA G.
LENGAIGNE M.
LENKA SREENU
LEVY M.
LIDITA KHANDEPARKER
LINA FERNANDES
LIPIKA PATNAIK
LOBSANG TSERING
LOKABHARATHI P. A.
LOKESH KUMAR PANDEY
LOTLIKER ANEESH
LUIS R. A. A.
LYDIA KIRUBA R.
MADHAN R.
MADHU N. V.
MAHALAKSHMI P.
MAHANTY M. M.
MAHENDER K.
MAJITHIYA D.
MAKSYUTOV S.
MAMATHA S. S.
MANEESHA K.
MANGESH GAUNS
MANI MURALI R.
MANI SANKAR
MANISH SINGH
MANJU NAIR P.
MANJULA R.
MANJUNATHA S. G.
MAPARI K. E.
MAQBOOL YOUSUF
MARIA J GONSALVES
MASSON S.
MATTHIEU LENGAIGNE
MAZUMDAR A.
MEHRA P.
MICHAEL G. S.
MIHIR KUMAR DASH
MILIND MUJUMDAR
240
239
124
10
164
228
121
146
126
209
133
270
217
208
135
2
164
163
15
81
281
193
250
20
111
29
52
197
65
23
15
23
279
149
242
239
36
51
8
157
132
226
285
169
122
215
32
5
174
78
24
226
133
140
7
195
193
281
167
268
88
83
211
115
228
255
81
261
16
20
22
118
121
174
285
291
31
38
165
209
109
80
122
123
41
247
275
167
169
281
150
277
163
226
298
OSICON-15
22-24 March 2015
MODI A.
MOHANAKUMAR K.
MONTEIRO M. C.
MORAJKAR S.
MUDRA LEKSHMI B.
MUGILARASAN M.
MUKHERJEE JAYATI
MULIK J. T.
MURALEEDHARAN K. R.
MURALEEDHARAN P. M.
MURTUGUDDE R.
MURTY T. V. R.
MURTY V. S. N.
MURUMKAR P.K.
MUTHUVEL A.
NAGARAJAN G. K.
NAGARJUNA RAO D.
NAGENDER NATH B.
NAGESWARARAO G.
NAIDU C. V.
NAIDU S. A.
NAIK B. G.
NAIK D. K.
NAIK G. P.
NAIK R.
NAQVI S. W. A.
NARAYAN S.
NASEERA K.
NAVEEN GANDHI
NAVEEN KUMAR K. R.
NAYAK G. N.
NEETU S.
NISARG MAKWANA
NISHA V.
NITESH SINHA
NITHEESH THOMAS
NITHYANANDAM K.
NOUFAL K. K.
NOYEL V.
NUPUR THAKKER
ONKAR CHAUHAN
PABITRA SINGHA
PADALKAR P. P.
PANDEY SUNITA S.
PANKAJAKSHAN T .
PAREKH A.
P CHAKRABORTY
PARTHIBAN G.
PARVATHI A.
PARVATHI V.
PATIL J. S.
PATTAN J. N.
PAVAN KUMAR N.
PAWAN DEWANGAN
PEDNEKAR P. S.
PERIASAMY R.
PHANINDRA REDDY A.
PHILIP L. WOODWORTH
PRABHAKAR NAYAK
PRACHI NAIK
PRADEEP KUMAR P.
PRAJITH A.
PRAKASH CHAUHAN
PRAKASH N.
PRAKASH T. A.
PRAKASHBABU C.
PRAMOD MAURYA
88
49
278
27
76
207
11
271
197
49
5
116
78
54
124
129
69
155
256
89
16
169
157
115
27
23
115
268
153
205
211
23
63
253
153
138
118
123
280
140
202
164
160
36
83
89
159
150
290
23
262
150
5
164
178
239
109
231
119
24
87
152
203
124
214
151
140
273
205
110
88
285
213
214
162
166
27
217
29
80
83
31
38
41
162
266
108
257
261
248
156
160
173
299
44
275
OSICON-15
22-24 March 2015
PRASAD K. V. S. R.
PRASANNA KUMAR S.
PRASANTH A. PILLAI
PRATIHARY A. K.
PRATIMA M. KESSARKAR
PREETHA R.
PRINCE PRAKASH
PRINCE PRAKASH J.
PRIYA RAUTH
PRIZOMWALA S.P.
PUNYASLOKE BHADURY
PURNACHANDRA RAO V.
RADHARANI SEN
RAGUMARAN S.
RAGURAMAN G.
RAHUL NAGESH
RAHUL S.
RAI A. K.
RAI SHAILENDRA
RAJ KUMAR
RAJANEESH M.
RAJAWAT A. S.
RAJEEV SARASWAT
RAJITH K.
RAJKUMAR J.
RAJU ATTADA
R MADHUSOODHANAN
RAMADASS G. A.
RAMAIAH N.
RAMAN V. AKKUR
RAMASWAMY V.
RAMESH K.
RAMESH KUMAR M.R.
RAMESH KUMAR YADAV
RAMPRASAD T.
RANADIP BANERJEE
RANGANATH L. R.
RAO A. D.
RAO A. R.
RAO P. S.
RAO R. R.
RASHITH P.
RASHMI KAKATKAR
RASHMI SHARMA
RASTOGI B. K.
RATHEESH R.
RATIRUPA BARDHAN
RAVIBABU MANDLA
RAVICHANDRAN M.
RAVINDER M.
REDDY N. P. C
REMSIYA V. R.
RESPLANDY L.
REVADEKAR J. V.
REVICHANDRAN C.
RITESH VIJAY
RITIKA K.
ROKADE M. A.
ROXY M. K.
RIYANKA R CHOWDHURY
ROY RODRIGUES
RYAN LUIS
SABEERALI C. T.
SABIN T. P.
SABU SEBASTIAN M
SABYASACHI SAUTYA
SACHIDANANDAN CHINNU
95
18
53
27
149
291
253
270
203
63
282
149
58
270
121
239
91
119
71
60
269
199
170
210
224
64
240
141
268
240
156
65
86
48
163
168
209
84
210
151
83
44
62
60
63
199
38
223
21
134
16
229
23
50
197
219
88
32
81
3
266
115
69
81
135
239
110
96
49
89
38
150
116
83
88
41
152
212
146
186
150
152
255
254
144
261
151
160
184
185
93
212
171
173
171
146
186
224
55
67
20
22
54
205
220
57
88
94
88
66
261
300
OSICON-15
22-24 March 2015
SACHIKO MOHANTY
SADHURAM Y.
SAHAI A. K.
SAHU K. C.
SAKTHIVEL MURUGAN S.
SALVI S. M.
SAMBHAJI MOTE
SAMSON G.
SANDEEP
SANDEEP K. K.
SANDEEP N.
SANGEETA MISHRA
SANGEETA NAIK
SANIL KUMAR V. V.
SANITHA SIVADAS
SANJANA M. C.
SANJIBA K BALIARSINGH
SANJO JOSE V.
SANKAR S.
SANTOSH KUMAR SINGH
SARAVANAN S.
SARKAR D.
SARMA V. V. S. S.
SAROJ K. DASH
SATARDEKAR P.
SATHIBABU Y.
SATHISH K.
SATHISH KUMAR D.
SATISH R. WATE
SATYA PRAKASH
SATYAM SRIVASTAVA
SATYANARAYANA Y
SAUMYA NAIR
SAURABH RATHORE
SAYANTANI OJHA
SENGUPTA D.
SHAILESH SALVI
SHAJI A.
SHAKUNTALA V. M.
SHAMAL MARATHE
SHANTA NAIR
SHENOI V. S.
SHENOY D. M.
SHERIN C. K.
SHERYL O. F.
SHINDE N.
SHIVA PRASAD S.
S. N. SANAGOUDRA
SHREYA S. JOSHI
SHYNI T. N.
SHYNU R.
SIBY KURIAN
SIJIKUMAR S.
SIMI MATHEW
SIMONTINI SENSARMA
SINGH A. K.
SINGH H. N.
SINGH P.
SINGH SHIKHA
SINGH T.
SIVAGAMI A.
SIVAKHOLUNDU K. M.
SIVAKUMAR K. U.
SIVARANJANI S.
SMITA MITBAVKAR
SMITA PANDEY
SMITHA R.
184
78
53
8
117
271
239
80
85
84
47
240
155
130
255
123
8
52
183
275
195
60
10
144
27
26
266
218
219
12
77
147
283
255
250
55
39
169
57
82
288
129
27
14
292
32
55
247
235
92
212
38
49
109
168
209
76
252
75
174
132
133
49
195
265
185
199
71
261
180
257
187
258
11
14
15
16
20
31
38
41
44
41
153
275
134
183
208
218
223
220
252
257
67
29
275
269
301
22
OSICON-15
22-24 March 2015
SMRATI GUPTA
SNEHA K. G.
SOJA LOUIS
SOMAYAJULU Y. K.
SOMNATH S. PAI
SONI S.
SONIYA SUKUMARAN
SREE HARSHA H.
SREELEKHA J.
SREENIVAS PENTAKOTA
SREEPADA R. A.
SRIDHAR IYER
SRINIVAS G.
SRINIVAS T. N. R.
SRINIVASA KUMAR T.
SRIRAM K.
SRIVASTAVA ATUL
STEEVEN PAUL Y.
SUBBARAO
SUBEESH M. P.
SUBIR MUKHOPADHYAY
S CHAKRABORTY
SUDHAKAR M.
SUDHARANI P.
SUDHEESH V.
SUDHIR KUMAR SINGH
SUJA S.
SUJATHA C. H.
SUJITH P. P.
SUMI A SAMAD
SUNDAR D.
SUNDAR R.
SUNDARARAJAN.S
SUNEET DWIVEDI
SUNITA PANDEY
SUPRIYA G. KARAPURKAR
SURESH I.
SURESH K.
SURESH T.
SURYACHANDRA RAO A.
SURYAKUMAR S.
SURYANARAYANA A.
SUSEENTHARAN V.
SWAPNA P.
TANUJA NIGAM
TATA SUDHAKAR
TEESHA MATHEW
TEMJENSANGBA IMCHEN
TERRAY P.
THAKUR N. L.
THANGAPRAKASH V. P.
THIRUNAVUKKARASU A.
THOMAS T. R. A.
THORAT B. R.
THULASIDAS K. R.
TRUPTI MARDIKAR
TYSON SEBASTIAN
UDAY GAONKAR
UDAYA BHASKAR T. V. S.
ULLAS N.
UMESH KUMAR SINGH
UNNI V. K.
UNNIKRISHNAN A. S.
USHA NATESAN
UTHAMAN C. P.
VAIGNAKAR D.
VARIKODEN H.
42
288
6
83
291
243
271
89
55
95
268
157
62
26
8
6
73
214
189
217
168
162
34
26
34
77
212
6
174
129
228
120
270
51
292
150
23
160
203
69
124
214
133
47
182
141
49
252
88
263
21
122
286
32
135
219
155
257
21
285
51
138
217
218
138
174
50
245
273
96
108
191
221
7
35
73
74
83
173
235
248
134
81
82
85
221
228
231
54
57
66
88
80
302
OSICON-15
22-24 March 2015
VEERASINGAM S.
VENGATESAN G.
VENKATACHALAPATHY R.
VENKATESAN R.
VENKATESH RAGHAVAN
VENUGOPAL REDDY
VETHAMONY P.
VIALARD J.
VIJAPURE TEJAL V.
VIJAY KUMAR
VIJAY KUMAR K.
VIJAYA RAVICHANDRAN
VIJITHA VIJAYAN
VIKAS M.
VIKASH K. KUSHWAHA
VIMALA J.
VIMLESH PANT
VINAYARAJ POLIYAPRAM
VINITA J.
VINU VALSALA
VISHAL PATIL
VIVEK KUMAR PANDEY
VIVEK S.
VIVEK SHILIMKAR
VOLVOIKAR S. P.
VYAS D. U.
VYSHNAVI P.
WASIM EZAZ
WILLIAM FERNANDES
YADHUNATH E. M.
YATHEESH V.
YOGESH AGARVADEKAR
207
137
207
67
130
112
207
23
271
188
115
133
288
189
220
65
84
130
197
5
239
77
95
94
211
145
224
252
126
178
164
115
65
109
120
132
137
80
273
183
191
137
111
182
75
257
88
261
127
232
217
303
OSICON-15
22-24 March 2015
304

osicon-15 - Ocean Society of India

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