Books of Abstracts August 12-14, 2021

OSICON-21OSICON-21

SeventhSeventh NaNationaltional ConferConferenceence ofof thethe OceanOcean SocietySociety ofof IndiaIndia Books of Abstracts August 12-14, 2021

Focal Theme: Ocean for Sustainable Development Dr. M. Ravichnadran President, Ocean Society of India (OSI) Director, National Centre for Polar and Ocean Research (NCPOR) Ministry of Earth Sciences (MoES), Goa

Welcome Message ational Centre for Polar and Ocean Research (NCPOR) of Ministry of Earth Sciences, Government of India proud to be the host for the 7ʰ biennial edition of the NNational Conference of the Ocean Society of India (OSICON-21) in collaboration with Ocean Society of India (OSI) from 12-14 August 2021. The COVID-19 pandemic has an immense global impact and has claimed many casualties. Our deepest condolences go out to the people who have lost a loved one and to the people who have suﬀered during this pandemic. This year, while we regret that the COVID-19 pandemic prevented us from holding the conference in Goa, we are excited about the opportunities of holding an innovative virtual conference.

The theme of the OSICON-21 three-day conference is “Ocean for Sustainable Development”. We expect that the online conference will enable you to share your research with other Indian Oceanographic communities and discuss the current issues related to research in Oceanography. There are three parallel sessions each day. The meeting includes a range of presentations, invited talks, oral presentations, and poster presentations, covering seven themes, viz (i) Marine ecosystems and Biogeochemistry of the Ocean, (ii) Coastal and open Ocean processes, (iii) Climate change, (iv) Polar Science and cryosphere, (v) Ocean Engineering and Technology, (vi) Marine Geology and Geophysics and (vii) Mathematics in Ocean sciences.

I would like to thank and acknowledge the Chief Guest, invited speakers, Chairman and coordinators of the session, LOC, GC-OSI, advisory commiee, sponsors, delegates, and the support team who have worked hard to make this conference a truly successful one. I request all the delegates and participants to take part in all the activities that we have come up with for three days.

I sincerely hope that this OSICON-21 conference will deliberate and discuss all the diﬀerent facets of Oceanography and come up with recommendations that will lead to the development of sustainable oceans.

I welcome you to this conference and look forward to your active and enthusiastic participation: we have so much to learn from each other.

With best regards,

(M. Ravichandran) President, OSI

2 Preface Dr. Avinash Kumar Dr. R.K. Mishra Dr. N. Anilkumar Co-Convener Co-Convener Convener

he Ocean Society of India (OSI), established in 2006, acts as a medium for partaking in the gen and know-how of the entities, industrial organizations, research institutions Temployed in the various regimes of the ocean. It is a professional society encompassing Academicians, Researchers, Technologists and Engineers from Universities, Scientiﬁc Institutions and Industries occupied in the Ocean-Atmospheric related investigations. The OSI provides gaits towards information amelioration for the research and development of our country.

OSI is organizing the OSICON biennial National Conference since 2009. Various reputed organizations and universities across the country have hosted the conference very successfully. Distinguished scientists, professors, research scholars, and students from several scientiﬁc institutes and universities have actively participated in the previous conferences. To date, six conferences are being conducted. The OSICON-21 is going to be held at National Centre for Polar and Ocean Research, Goa, during 12-14 August 2021. The conference is planned to be conducted on a virtual (online) platform.

It is a prestigious tribute for us to release the Book of Abstracts of Seventh Biennial Conference of Ocean Society of India (OSI), organised by the National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Government of India. We have received a prodigious riposte and splendid quality abstracts for all the scientiﬁc themes included in the present conference.

Ocean, as an ecological unit, molliﬁes the global weather and climate. Nonetheless, due to the anthropogenic interferences, most of the ocean environments are geing too vulnerable to alleviate the climatic conditions. Accordingly, United Nations (UN) has asserted 'Decade of Ocean Science for Sustainable Development (2021-2030)' to enlighten mankind about the importance of the role of oceans in climatic variabilities. India’s Deep Ocean Mission launching will throw light on the unknown resources and their extraction from the deep ocean regimes. OSICON-21 provided an exceptional platform for the researchers in India to discuss their ﬁndings and future outlooks in the major themes Marine Ecosystem and Biogeochemistry of the Ocean, Climate and Climate Change, Coastal and open Ocean processes, Marine Geology and Geophysics, Ocean Engineering and Technology, Polar Science and Cryosphere, Mathematics in Ocean Science. The necessity for partaking in dazzling and inspiring concepts in this vital area of research is encountered with identical fervour and sustenance from the contributors as perceived from their retort to this platform.

3 PREFACE 4

The technical commiee carried out the peer review of all the abstracts with Dr. Prasad Bhaskaran, IIT, Kharagpur as the chairman. We express our sincere gratitude to all reviewers who helped us include the high-quality research papers in the conference proceedings.

This Abstracts volume has 113 oral presentations and 103 poster presentations spread over 7 themes. Considering the present COVID scenario, only so copies of the conference proceedings were made available. This proceedings volume with abstracts is made to give wider publicity for the admirable scientiﬁc investigations going on in our country in the focal themes of this conference.

We are exceptionally thankful to The President and GC Members of OSI for providing us with an opportunity to deliver our best eﬀorts for the accomplishment of this conference.

We are assertive that the scientiﬁc and technical contributions made by all the authors, invited speakers, chairmen and coordinators, advertisers, exhibitors, sponsors, and participants in this conference will augment to ﬁll the knowledge gap in the various remote regimes of the oceans. We extend our sincere gratefulness to all the contributors.

All members of the Organizing Commiee, especially Dr. Ravidas K Naik, Dr. Rohit Srivastava, Mr. Lalit Ahirwar, Dr. P. Sabu, Dr. Jenson V George, and all Technical Commiees members are extensively acknowledged for their immense support to conduct this conference successfully.

We trust that OSICON-21 is the best juncture for making associations among the researchers. We delivered our responsibilities sincerely for the success of this conference and sorry for the apprehensions faced by you, if any. We wish you all a fruitful meeting.

Avinash Kumar R.K. Mishra N. Anilkumar Co-Convener Co-Convener Convener Committees

Advisory Committee

Dr. Madhavan Nair Rajeevan, Former-Secretary, Ministry of Earth Sciences (MoES), Government of India

Shailesh Nayak, Former-Secretary, MoES and Director, National Institute of Advanced Studies, Bengaluru.

Dr. M. Mohapatra, DGM, IMD

Dr. Prakash Chauhan, Director, IIRS

Dr. Raj Kumar, Director, NRSC

Dr. Virendra M. Tiwari, Director, NGRI

Prof. Sunil Kumar Singh, Director, NIO

Dr. A. Gopalakrishnan, Director, CMFRI

Prof. Ravishankar Nanjundiah, Director, IITM

Dr. M.V. Ramana Murthy, Director, NCCR

Dr. G.A. Ramadass, Director, NIOT

Dr. Srinivasa Kumar, Director, INCOIS

Prof. Jyotiranjan S. Ray, Director, NCESS

Dr. G.V.M Gupta, Director, CMLRE

Dr. O.R. Nandagopan, Director, NSTL

Mr. S. Vijayn Pillai, Director, NPOL

Dr. M. Baba, Former Director, CESS

Dr. N.P. Kurian, Former Director, NCESS

M. Ravichandran, Director, NCPOR, President, OSI

Dr. Basanta Kumar Jena, Gen. Secretary, OSI

5 COMMITTEES 6 Organizing Committee

Dr. M. Ravichandran, NCPOR (Chairman)

Dr. N. Anilkumar, Convener, NCPOR

Dr. R.K. Mishra, Co-Convener, NCPOR

Dr. Avinash Kumar, Co-Convener, NCPOR

Prof. H.B. Menon, Member, Goa University

Dr. S.C. Tripathy, Member, NCPOR

Dr. Mani Murali R, Member, CSIR-NIO

Mr. Lalit Kumar Ahirwar, Member, NCPOR

Dr. P. Sabu, Member, NCPOR

Dr. P.V. Bhaskar, Member, NCPOR

Dr. Rohit Srivastava, Member, NCPOR

Dr. Nuncio Murukesh, Member, NCPOR

Dr. Jenson George, Member, NCPOR

Dr. Ravidas K. Naik, Member, NCPOR COMMITTEES 7 OSI- Governing Council

Dr. M. Ravichandran, President

Dr. N.P. Kurian, Vice President

Dr. Tata Sudhakar, Vice President

Dr. Basanta Kumar Jena, Gen. Secretary

Prof. Prasad K. Bhaskaran, Joint Secretary

Dr. Mani Murali, Joint Secretary

Dr. Smitha Balraj, Treasurer

Dr. M. Baba, Member

Dr. Vinu Valsala, Member

Dr. Anand P., Member

Mr. Eluri Pattabhi Ramarao, Member

Dr. Prasad K.V.S., Member

Dr. Kankara R.S., Member

Dr. Jossia Joseph K., Member

Dr. Vimlesh Pant, Member

Dr. Marathadu Sudhakar, Ex-Oﬃcio Member

Dr. C. Revichandran, Ex-Oﬃcio Member

Prof. Jayachandran K.V., Chairman, Kochi Chapter

Dr. Supriyo Chakraborty, Chairman, Pune Chapter

Prof. Balasubramaniam, Chairman, Chennai Chapter

th Time 12 AUGUST 2021: DAY 1

INAUGURATION 09:30 - 11:30 PLENARY TALK BY HON. FELLOW

11:30 - 11:45 TEA BREAK Bharati Hall Maitri Hall Himadri Hall PARALLEL SESSION 1 PARALLEL SESSION 2 PARALLEL SESSION 3 (Technical session-1) (Technical session-2) (Technical session-3) Marine Ecosystems and Coastal and Open Ocean Climate Change (CC) Biogeochemistry of the Ocean processes (COOP) (MEBO) Session Chairman: Session Chairman: Sessions Chairman: Prof. K.V. Jayachandran, KSBB Dr. Sanil Kumar VV, NIO Dr. D Bala Subrahamanyam, Session Coordinators: Session Coordinators: SPL 11:45 – 13:00 Dr. Siby Kurian, NIO Dr. Anilkumar V, CMLRE Session Coordinators: Dr. Sabu P, NCPOR Dr. Prince Prakash, NCPOR Dr. Anoop S. Mahajan, IITM Dr. Nuncio M, NCPOR

INVITED TALK: INVITED TALK: INVITED TALK: Dr. GVM Gupta, CMLRE Dr. Srinivasa Kumar, INCOIS Dr. Raghu Murtugudde, “Are Indian coastal seas really “Ocean Observations, information University of Maryland, USA polluted? – Myths and Effects” and Advisory services” "Climate change and the seas around us: India and the Ocean"

13:00 – 14:00 LUNCH BREAK Bharati Hall Maitri Hall Himadri Hall PARALLEL SESSION 1 PARALLEL SESSION 2 PARALLEL SESSION 3 (Technical session-4) (Technical session-5) (Technical session-6) Marine Ecosystems and Coastal and Open Ocean Climate Change (CC) Biogeochemistry of the Ocean processes (COOP) 14:00 – 16:00 (MEBO) Session Chairman: Session Chairman: Session Chairman: Dr. C. Revichandran, NIO Prof. A. D. Rao, IITD Dr. Supriyo Chakraborty, IITM Session Coordinators: Session Coordinators: Session Coordinators: Dr. Anand. P, NPOL Dr. Mani Murali, NIO Dr. Kripa Ram, BHU Sh. Vikash Kumar, NCPOR Dr. Parijat Roy, NCPOR Dr. Parmanand Sharma, NCPOR

16:00 – 16:15 TEA BREAK Technical session-4 Technical session-5 Technical session-6 MEBO Contd…. COOP Contd…. CC Contd…. 16:15 – 17:30

th Time 13 AUGUST 2021: DAY 2 Bharati Hall Maitri Hall Himadri Hall PARALLEL SESSION 1 PARALLEL SESSION 2 PARALLEL SESSION 3 (Technical session-7) (Technical session-8) (Technical session-9) Marine Ecosystems and Coastal and Open Ocean Ocean Engineering and Biogeochemistry of the Ocean processes (COOP) Technology (OET) (MEBO) Session Chairman: Session Chairman: Sessions Chairman: Dr T. Balasurbramaniam, CARE Dr. M Baba, Dr. MA Atmanand, IIT-M Session Coordinators: Former Director, CESS Session Coordinators: 9:30 – 11:30 Dr. Samir Damare, NIO Session Coordinators: Sh. PK Maurya, NIO Dr. Waliur Rahaman, NCPOR Dr. L Sheela Nair, NCESS Dr. A Mukherjee, NCPOR Dr. Melena A Soares, NCPOR INVITED TALK: INVITED TALK: INVITED TALK: Prof. Sunil Kumar Singh, NIO Prof. B.N. Goswami, Cotton Dr. M.V. Ramana Murthy, NCCR "The importance of Geotracers University, Guwahati “Recent trends in Coastal Program and way forward" "Local Ocean-atmosphere Research and Sustainable Coastal Interactions associated with the Technologies” Indian Monsoon Multi-decadal Mode" 11:30 – 11:45 TEA BREAK Technical session-7 Technical session-8 Technical session-9 11:45 – 13:00 MEBO Contd…. COOP Contd…. OET Contd….

13:00 – 14:00 LUNCH BREAK Bharati Hall Maitri Hall Himadri Hall PARALLEL SESSION 1 PARALLEL SESSION 2 PARALLEL SESSION 3 (Technical session-10) (Technical session-11) (Technical session-12) Marine Ecosystems and Coastal and Open Ocean Ocean Engineering and Biogeochemistry of the Ocean processes (COOP) Technology (OET) (MEBO) Session Chairman: Session Chairman: Session Chairman: Prof. Parthasarathi Chakraborty, IIT- Dr. S. Satheesh Shenoi, Former Dr. NP Kurian, 14:00 – 16:00 KGP Director, INCOIS Former Director, NCESS Session Coordinators: Session Coordinators: Session Coordinators: Dr. Damodar Shenoy, NIO Dr. Rajdeep Roy, NRSC Dr. Suprit Kumar, INCOIS Dr. Bhaskar PV, NCPOR Dr. V Venkataramana, NCPOR Dr. Sarat Tripathy, NCPOR INVITED TALK: INVITED TALK: INVITED TALK: Dr. Vinu Valsala, IITM Dr. N Ramaiah Dr. Joseph Mathew, Sanctuary "Importance of Biogeochemistry of Former Chief Scientist, NIO Beach Pvt. Ltd., Singapore. Indian Ocean and way forward" “Sustainable Indian seas through “Coastal processes and coastal enhanced biological research” protection challenges"

16:00 – 16:15 TEA BREAK Technical session-10 Technical session-11 COOP 16:15 – 17:30 MEBO Contd…. Contd….

th Time 14 AUGUST 2021: DAY 3 Bharati Hall Maitri Hall Himadri Hall PARALLEL SESSION 1 PARALLEL SESSION 2 PARALLEL SESSION 3 Technical session-13 Technical session-14 Technical session-15 Polar Science and Cryosphere Coastal and Open Ocean Ocean Engineering and studies (PSC) processes (COOP) Technology (OET) Session Chairman: Session Chairman: Sessions Chairman: Dr. M. Sudhakar, Former Director, Dr. Rashmi Sharma, SAC/ISRO Prof. Prasad K Bhaskaran, IIT- CMLRE Session Coordinators: KGP 9:30 – 11:30 Session Coordinators: Dr. Smitha Balraj, CMLRE Session Coordinators: Dr Vimlesh Pant, IITD Dr. Bajish C.C., NCPOR Dr. Jossia Joseph, NIOT Dr. Babula Jena, NCPOR Dr. R Srivastava, NCPOR INVITED TALK: INVITED TALK: INVITED TALK: Dr. N. Anilkumar, NCPOR Dr. Prakash Chauhan, IIRS/ISRO Dr. GA Ramadass, NIOT "Decadal Indian Observational “Satellite Based Ocean Observing “Technology for exploration of Campaigns in the Southern Ocean and and the Blue Economy" Ocean Resources” the Future perspectives"

11:30 – 11:45 TEA BREAK Bharati Hall Maitri Hall Himadri Hall 11:45 – 12:15 Technical session-13 PARALLEL SESSION 2 PARALLEL SESSION 3 PSC Contd…. Technical session-14 Technical session-15 PARALLEL SESSION 1 (Technical session-16) COOP Contd…. OET Contd…. Marine Geology and Geophysics (MGG)

Session Chairman: 12:30 – 13:00 Dr. K.A. Kamesh Raju, NCPOR Session Coordinators: Dr. Rajeev Saraswat, NIO Dr. Mahesh B.S., NCPOR INVITED TALK: Prof. Jyotiranjan S Ray, NCESS "Outstanding Research Questions in Indian Ocean Tectonics" 13:00 – 14:00 LUNCH BREAK Technical session-16 PARALLEL SESSION 2 PARALLEL SESSION 3 Technical session-17 Technical session-18 MGG Contd…. Mathematics in Ocean Science Ocean Engineering and (MOS) Technology (OET) 14:00 – 16:00 Session Chairman: Session Chairman: Dr. C. Gnanaseelan, IITM Dr. R. Venkatesan,NIOT Session Coordinators: Session Coordinators: Dr. Kunal Chakraborty, Dr. Sourav Mandal, NIO Sh. S. Chatterjee, NCPOR Mr. Prasad Dudhgaonkar, NIOT 16:00 – 17:00 Valedictory Function Contents

Welcome message2

Preface3

Committees5 PLENARY TALK...... 1

Marine Ecosystems and Biogeochemistry of the Ocean (MEBO)2 Analysis of microplastics in water samples collected from ﬁve sewage treatment plants of Kolkata (Runkob Srimani, Ravidas K. Naik).....4 Estimation and Identifcation of Microplastics & Heavy Metals Ingested by Fishes in Kerala (Nithya Thulasidharan, C.R. Emil John, R. S. Sruthi Thalayappil, P. T. Mathew )...... 5 Estimation and Identifcation of Heavy Metals in Seawage Water (Gowathamy Satheesan, K. K. Darsana, R. S. Sruthi Thalayappil, P.T. Mathew).6 Did COVID-19 impact the Net Primary Productivity in the Arabian Sea? (Sunanda N., Jayanarayanan Kuttippurath, Arun Chakraborty, Rony Peter)...... 7 The Role of Organic Nutrients on the Sustainability of Primary Production in the Bay of Benagal (Sreevidhya R)...... 8 Monitoring of farmed shrimps (Penaeus vannamei) from Nagapattinam region of Tamil Nadu, India for Salmonella contamination (Akalesh, Geevaretnam Jeyasekaran, Robinsondhas Jeya Shakila, Theivasiga- mani Anand)...... 9 Assessment of Formaldehyde over the Indian Ocean and its impact on the Marine Environment (Gopikrishnan G. S, Jayanarayanan Kuttippu- rath)...... 10 Understanding the distribution of plastics in lower Ganga basin and their fate in river & marine waters (Gopala Krishna Darbha)...... 11 Microplastics in Marine and Freshwater System: A Review on Micro plastics and Heavy Metals Accumulation on Fishes (C. R. Emil John, Nithya Thulasidharan, R. S. Sruthi Thalayappil, P. T. Mathew)... 12 Assessment of seasonal cycle of physical and biological variables from CMIP6 ocean biogeochemistry models over the tropical Indian Ocean (Biswarup Bhattacharya, Sachiko Mohanty, Charu Singh)...... 13 Analysis of Water Quality of Samples Collected from Ernakulam, Alap- puzha and Kottayam Regions, Kerala, India (Darsana K. K., Gowthamy Satheeshan, R. S. Sruthi Thalayappil, P. T. Mathew)...... 14

11 CONTENTS 12

Biophysical Control on Variability in Phytoplankton Production and Com- position in the South-Western Tropical Indian Ocean during Monsoon (Sarat C. Tripathy , P. Sabu , Sivaji Patra , Ravidas K. Naik, Amit Sarkar, Vankara Venkataramana , Anvita U. Kerkar , P. Sudarsanarao) 15 Interannual and spatial variability of bio-optical characteristics in the In- dian sector of Southern Ocean during austral summer (Sudarsana Rao Pandi, Sarat C. Tripathy, S. S. Shaju ,P. Minu, Anvita U. Kerkar, Deepti V. G. Dessai, C. C. Bajish, N. Anilkumar )...... 16 Microbial carbon pump: Reservoir for ocean carbon- future prospects for carbon sequestration (Lata Gawade ,Venkataramana Vankara).... 17 Inter-annual variability of zooplankton assemblages in the Indian sector of the Southern Ocean (V. Venkataramana, R.K. Mishra, Anvita U. Kerkar, N. Anilkumar)...... 18 Factors controlling the Interannual variability of Particulate Organic Mat- ter Characteristics in the Indian Sector of the Southern Ocean (Me- lena A. Soares, N. Anilkumar, P. Sabu, V. Venkataramana , R. K. Naik, R. K. Mishra, R. Chacko, A. Sarkar)...... 19 Evaluate the Impact of marine pollution in the tourist beach Gopalpur, Bay of Bengal (Debasis Rath, Mukunda Kesari Khadanga, Sheshdev Patro)...... 20 Spatial and seasonal trends of trace metals in the surfacial Sediments from oﬀ Kochi - Geochemistry and Environmental Implications (Princy M John, Vishnu Murali, Priya Varghese, Anu Gopinath)...... 21 Impact of Siderophore producing bacteria, iron, and dissolved siderophore on coccolithophore and diatom monocultures (Parli V Bhaskar, Alok K Sinha , Jane T Bhaskar)...... 22 Impact of heavy load nutrient on Seagrass growth in tropical environment: A review article (Anil Kumar Behera, Mukunda Kesari Khadanga and Sheshdev Patro)...... 23 Characterization of extracellular enzyme activities of bacteria from the water and sediment sand along the west coast of India during monsoon season. (Ashutosh S. Parab, Mayukhmita Ghose, Cathrine S. Manohar) 24 Morphological and taxonomic diversity of micro-phytoplankton from the south-eastern Arabian Sea during 2020 winter monsoon: elucidation from surface and sub-surface chlorophyll maximum layers (Paul P., Patil J. S. )...... 25 Kinetic speciation of Cu,Ni,Co in Deep Sea sediment from the Central In- dian Ocean Basin (Lamjahao Sitlhou, Sucharita Chakraborty, Prasad Padalkar, Kartheek Chennuri, Ishita Ishita, N. H. Khadge, Parthasarathi Chakraborty)...... 26 Frontal variability of Phytoplankton in the Indian sector of Southern Ocean during Austral Summer 2018 (Sreerag A., R. K. Mishra, Ravidas K. Naik,Melena A. Soares, Resha Mahale)...... 27 Seasonal variation of POC in Bay of Bengal using Satellite Data (Soubhik Bhattacharya, Sudeep Das, Sourav Sil, Syed Hillal Farooq)...... 28 Emergence of omics as a tool to study life in the Oceans (Samir R. Damare) 29 CONTENTS 13

Salinity changes may influence dinoflagellate cyst morphometry: data from monsoon influenced tropical coastal ecosystems (R. V. Rodrigues, J. S. Patil )...... 30 Marker pigment based phytoplankton community structure in relation to wind forcing in the central Arabian Sea: SW monsoon (2017-2018) (Mintu Chowdhury, Haimanti Biswas)...... 31 Simulated ocean acidification and Cu enrichment promote pennate diatom dominance in the central Arabian Sea (Diksha Sharma, Haimanti Biswas)...... 32 13 15 The impacts of physical forcing on POM, δ CPOC and δ NPN variability in the central Arabian Sea during SW monsoon (2017-2018) (Saumya Silori, Haimanti Biswas)...... 33 Potential of marine bacteria for biodegradation of polycyclic aromatic hydrocarbon (Vasudha C. Bhatawadekar, Samir R. Damare)...... 34 Effect of nutrient enrichment under pressure on the microbial diversity- A metagenomic approach (Shruti Shah Samir Damare)...... 35 Phytoplankton community structure in relation to the environmental conditions from the tropical Kandla port ecosystem (Aseem R. Rath, Smita Mitbavkar, A. C. Anil)...... 36 Impact of Covid-19 lockdown on the base of marine food web in the North Indian Ocean (Swastika Bhaumik)...... 37 Development of a bioenergetics model for Indian oil sardine (Sardinella longiceps) and simulation of its seasonal growth along the Indian west coast (Faseela Hamza, Anju M, Vinu Valsala, Smitha B.R.)..... 38 Iron biogeochemistry in the Southern Ocean (Diptangshu Sarkar, Parthasarathi Chakraborty)...... 39 The first report of seasonal distribution of phytoplankton functional type (PFT) & phytoplankton size classes (PSC) in Chilika, the largest coastal lagoon in India (Sambit Singh, Tamoghna Acharyya, Anu Gopinath)...... 40 Abundance and Distribution of Microplastics in the Water Column of Southern Ocean (E.V.Ramasamy, Ajay Kumar Harit, Naveen Babu ) 41 Environmental interaction of water quality, phytoplankton and zooplankton in pelagic food web of Ghogha coastal waters in Gujarat (S. Sun- daramoorthy, G. Idayachandiran , J. Jaganmohan)...... 42 Biophysical interactions over the tropical Indian ocean in a changing climate (Aditi Modi , Roxy M. K. , S. Ghosh)...... 43 Marine Algae : A Great Human Food Source (Shreya Suresh Moraskar).. 44 A simple technique to mitigate microplastic pollution and its mobility (via ballast water) in the global ocean (Ravidas Krishna Naik, Parthasarathi Chakraborty, Priya M. D’Costa, Anilkumar N., R. K. Mishra, Veliton Fernandes)...... 45 Application of machine learning to predict the copepod-bacterial association (Balamurugan Sadaiappan, Manguesh U Gauns)...... 46 CONTENTS 14

Variability in diatom frustule and dinoflagellate cyst in the short sediment coresfrom two locations in the eastern Arabian Sea (Medhavi Pandey, Haimanti Biswas, Maria Hilda Joao)...... 47 Sea foam: A unique habitat in the marine Ecosystem (Meenakshi, Priya M. D’Costa)...... 48 Algicidal bacteria as a promising candidate for control of harmful algal blooms (S. V. Sandhya)...... 49 The first report on spatio-temporal distribution of Chromophoric Dissolved Organic Matter (CDOM) in Chilika, the largest coastal lagoon in India (Susmita Raulo, Sambit Singh, Tamoghna Acharyya)...... 50 The Observed Variability of Dissolved Oxygen, Chlorophyll and CDOM along the South Eastern Arabian Sea waters (Deepulal P. M., AnilKu- mar K., Harikrishnan M., Raghunadha Rao A., Akhil V.S.)...... 51 Biotechnological Potential of Diatoms (Harsha Gaonkar, Priya M. D’Costa) 52 Distribution of microplastics in coastal regions of India (Blossom Dias, Varada S. Damare)...... 53 Oil spill in marine environment and associated microbiology (Mrinalini Chandra Mohan, Varada S. Damare)...... 54 Accumulation of Petroleum Hydrocarbons in Zooplankton at Nagapatti- nam coastal water, Bay of Bengal, South East coast of India (Srini- vasan Sundararajan, Mukunda Kesari Khadanga, Balasubramanian Kamalakannan, Asim Amitav Pattanayak, Basanta Kumara Jena).. 55 Spatiotemporal distribution of diatom community with distinct salinity regimes along the Kali estuary, Karwar, West Coast of India (Akshata Naik, Shivakumar Haragi)...... 56 Ingression and seasonal abundance of Decapoda Larvae along the Kali estuary, Karwar, West Coast of India (Rajeshree Pednekar, Shivakumar Haragi)...... 57 Application of CROCO+NPZD model to simulate the coastal biochemical variability (D Sathish Kumar, Uma Sankar Panda, Umakanta Pradhan, Pravakar Mishra, M. V. Ramana Murthy)...... 58 The Preliminary study of coastal water acidification monitoring in the Palk Bay, Southeast coast of India (Balasubramanian Kamalakan- nan, Srinivasan Sundararajan, Basanta Kumara Jena, Asim Amitav Pattanayak, Mukunda Kesari Khadanga)...... 59 Evaluation of the heavy metal pollution in the estuarine ecosystem of Tapi and its sustainable management, Arabian Sea (Mukunda Ke- sari Khadanga, Balasubramanian Kamalakannan, Asim Amitav Pat- tanayak, Srinivasan Sundararajan, Basanta Kumara Jena)...... 60 Development of a coupled physical biogeochemical model for the Indian Ocean (Anju Mallissery, Vinu Valsala, Prajeesh A G)...... 61 Determination of Bioaccumulation in Marine Ecosystem by Laser induced Breakdown Spectroscopy (Della Thomas, S. Surendran, N. J. Vasa). 62 Two New Carnivorous sponge (Porifera, Cladorhizidae) species from the Central Indian Ridge Seamounts (Periasamy R., P. J. Kurian, B. S. Ingole)...... 63 CONTENTS 15

Climate change (CC) 64 Future Projection of Indian Ocean Temperatures Under Global Warming (A. Anusree, M. K. Roxy)...... 66 Performance of COWCLIP Significant Wave Height datasets and Extreme Wave Height Projections for the Indian Ocean (Athira Krishnan, Prasad K Bhaskaran, Prashanth Kumar)...... 67 Response of Ocean Heat Content variability on Cyclone Frequency over North Indian Ocean (Jiya Albert, Prasad K Bhaskaran)...... 68 Studies on tropical zooplankton and climate change, west coast of India (Kadam Surendra S, Samal Deepika V )...... 69 Genesis and trends in marine heatwaves over the tropical Indian Ocean and their interaction with the Indian summer monsoon (J. S. Saranya, M. K. Roxy, Panini Dasgupta, Ajay Anand)...... 70 Relationship between Azores High and Indian summer monsoon (Ramesh Kumar Yadav)...... 71 Footprints of Southern Annular Mode on The Indian Ocean Waves (Meenakshi Sreejith)...... 72 The physiological response of Scylla serrata under the influence of climate change related factors and oil pollution (Sritama Baag, Sumit Mandal) 73 Modeling the drivers of the spatiotemporal variability of the surface pCO2 in the Bay of Bengal (A. P. Joshi, V. Kumar, H. V. Warrior).... 74 Ocean warming over the past three decades: Implications on Arctic methane emissions caused by hydrate dissociation (Akash Trivedi, Sudipta Sarkar) 75 Denitrification record from Eastern Arabian Sea indicating South Asian Monsoon Variability during late Pliocene (Padmasini Behera, Manish Tiwari)...... 76 Regional Modeling of Extreme Temperature Trends over India (Nishtha Agrawal ,Vivek Kumar Pandey )...... 77 Bi-decadal variation of saltwater vulnerability in coastal district of Raigad, Maharashtra, India. (Barnali Das, Anargha Dhorde)...... 78 The decadal sea level variability observed in the Indian Ocean tide gauge records and its association with global climate modes (J.S. Deepa, C. Gnanaseelan)...... 79 India’s Mission of a ‘Clean and Green Navy’ (Arjun)...... 80 Primary Productivity and Bio-optical Variability in the Indian Sector of the Southern Ocean: Observations from Austral Summer 2015 (Anvita U. Kerkar, S. C. Tripathy, P. Minu, N. Baranval, P. Sabu, S. Patra, R. K. Mishra, A. Sarkar)...... 81 Frequency of monsoon depression over the Indian seas and landmass during onset, withdrawal, and mainmonsoon season and the associated rainfall variability (Sanjukta Rani Padhi and Pratap Kumar Mohanty) 82 Combined Influence of ENSO and IOD on the strength of Northeast Mon- soon Rainfall over the peninsular India (E.K. Simon, R. Sajeev, Basil Mathew)...... 83 CONTENTS 16

Demonstrating the potential of Regional Ocean Model System (ROMS) in simulating the upper ocean characteristic over Arabian Sea: impact of horizontal resolution (Prabha Kushwaha )...... 84 West Pacific subtropical high, typhoon activity over northwest Pacific and linkage with Indian summer monsoon rainfall (Roja Chaluvadi, Hamza Varikoden, Milind Mujumdar, S. T. Ingle)...... 85 Long-term changes in monsoon winds in response to ocean warming (Par- vathy Anil, M. K. Roxy)...... 86 CMIP5 and CMIP6 fidelity in representing the IPOC mode characteristics and its link with the Indian summer monsoon rainfall (Darshana D Patekar, Jasti S Chowdary, C. Gnanaseelan and Anant Parekh)... 87 Benefits of satellite XCO2 and newly proposed atmospheric CO2 observation network over India in constraining Indian Ocean prior fluxes (Santanu Halder, Yogesh K. Tiwari, Vinu Valsala)...... 88 Assessment of climate variability in coastal wetlands of Pichavaram mangroves through satellite images (T. German Amali Jacintha, Radhika Rajasree. S.R, J. Sriganesh)...... 89 Intraseasonal oscillation of boreal monsoon rainfall and its coherence with meridional sea surface temperature gradient in the Bay of Bengal (Reji M. J. K., Hamza Varikoden, C. A. Babu)...... 90 Analysis of the intensity and rate of tropical expansion (Parvathy M, Roxy Mathew Koll)...... 91 Relationship between Global SST and Summer Monsoon Rainfall in Six Intensity Bins over Five Homogenous Regions in India (Reshma T, Hamza Varikoden, C. A. Babu)...... 92

Coastal and Open Ocean processes (COOP) 93 Decadal Shoreline Morphological Changes Using Satellite Images of Goa Coast (Shanmuga Priyaa S, Aruna Kumar Avula, Basanta Kumar Jena, M. V. Ramana Murthy)...... 95 Experimental Study on Wave Transmission and Run-up over Submerged Vegetation (Muni Reddy M.G, Giridhar G., Ganesh A.)...... 96 Oxidised volatile organic compounds in the Indian Ocean and Southern Ocean marine boundary layer (Anoop Mahajan, Swaleha Inamdar). 97 The Spatial and temporal variability of OH minimum over Indian ocean (Ardra D., Jayanarayanan Kuttippurath)...... 98 Role of sea surface temperature anomalies of Arabian Sea in extreme weather events at western coast of Indian subcontinent (Niket Shastri, K. N. Pathak)...... 99 Validation of CMIP6 with the observations of SST in the Bay of Bengal (V. Kumar, A.P. Joshi, H.V. Warrior)...... 100 Aerosol distribution over the tropical Indian ocean and the role of atmospheric thermodynamics (A. A. Shaikh, N. Shaikh, S. Hulswar, H.B. Menon)...... 101 CONTENTS 17

Assessment of Nutrient Bioavailability and Trophic Status of Beypore Es- tuary, Southwest India (Rose Santhosh, Renjith K. R., Vivek B., Ihjas K., Digila Rani M. and Celine George)...... 102 Geographical Mapping System (GMS): An improved GIS in Disaster Man- agement (Sanjaya Kumar Sarangi, Mrutyunjaya Panda)...... 103 Black Carbon characteristics over Indian ocean sector of the southern ocean (Rohit Srivastava, A. Asutosh, P. Sabu, N. Anilkumar)...... 104 To study the influence of Indian Ocean Dipole on Southern Hemisphere circulation during austral spring (Shrutee Jalan, Pranab Deb).... 105 Trends in tropical cyclone rainfall over the Bay of Bengal during the past two decades (R. Harikrishnan , M. K. Roxy)...... 106 Wave transformation and attenuation along the central Kerala coast of India using Mike21 SW Model (Vasudevan S., Sajeev R.)...... 107 Temperature sensor location optimization of expendable bathy thermograph using numerical method (Sona M. A., Anshath Hussain N., Vibin M. V. and Anand P.)...... 108 Atlantic hurricanes of 2020 and the factors influencing them (Sidha Sankalpa Moharana, Debadatta Swain)...... 109 Spatio-temporal Variability of Bio-optical Properties and Radiant Heating Rate in the Eastern Arabian Sea (Partha A. Patil, Arjun Adhikari, Harilal B. Menon)...... 110 Simulation with Eddy Resolving High Resolution (1/12o)Global NEMO Ocean Model (Imranali M. Momin, A. K. Mitra, J. P. George, M. Martin, J. Waters, A. Aguiar)...... 111 Mesoscale circulation features on the northwestern Bay of Bengal using HF radars observations (Anupama Sahoo, Shouvik Dey, Sourav Sil)... 112 The Known and Unknown Mysteries of Marine Atmosphreic Boundary Layer under the influence of a Tropical Cyclone: A Case Study during OCKHI Storm (D. Bala Subrahamanyam,Roshny S., Freddy P. Paul, Anurose T. J., Radhika Ramachandran)...... 113 ROMS Simulations of Physical and Biogeochemical Parameters for ’NAR- GIS’ cyclone in the Bay of Bengal (Tarumay Ghoshal, Arun Chakraborty)114 Future projection of wave characteristics using CMIP6 wind along south Odisha coast (Subhasis Pradhan, Pratap Kumar Mohanty, Rabindro Nath Samal, Madan Mohan Mohanty, Prabin Kumar Kar)...... 115 Inflow and spreading of the Red Sea and Persian Gulf water into the western Arabian Sea (Sankar Prasad Lahiri, Vimlesh Pant)...... 116 Dynamics of mercury in a monsoon fed tropical estuarine system during dry season (Saranya Jayachandran, Parthasarathi Chakraborty, Prasad Padalkar, Lamjahao Sitlhou, Kartheek Chennuri)...... 117 Seasonal and Intraseasonal Variability of Winds and Associated Air-Sea Interaction in the Bay of Bengal from a Moored Buoy Observation (Sumana Mandal, Arkaprava Ray, Sourav Sil, R. Venkatesan).... 118 Observations of currents in the Sri Lankan dome using in-situ, satellite, and re-analysed data (Athira K, Rajith K, Harikrishnan M, Dominic Ricky Fernandez)...... 119 CONTENTS 18

Surface circulation features in the western Aandaman Sea: Observations from HF RADAR (Samiran Mandal, Sourav Sil, Avijit Gangopadhyay)120 Understanding iodine emissions in the Indian and Southern Ocean marine boundary layer (Swaleha Inamdar, Liselotte Tinel, Qinyi Li, Alba Ba- dia, Alfonso Saiz-Lopez, Kirpa Ram, Rosie Chance, Lucy Carpenter, Anoop Sharad Mahajan)...... 121 Third Revision of the Bottom-up Global Surface Seawater Dimethyl Sulﬁde Climatology (DMS-Rev3) (Shrivardhan Hulswar, Rafel Simo, Mart´ı Gal´ı,Tom Bell, Arancha Lana, Swaleha Inamdar, Anoop S. Mahajan) 122 Impact of COVID-19 associated lockdowns on the year-to-year variability of oil pollution along the Eastern Arabian Sea (V. Trinadha Rao, Suneel V. , Istuti Rajavanshi, Alex M.J, Antony P Thomas )..... 123 Numerical interaction on tide, wind, wave & current oﬀ Gulf of Khambhat (Susant Kumar Misra, J. Guru Prasath, R. C. Bragath, P. Chan- dramohan)...... 124 Sustainable management of shoreline near Mahabalipuram (J. Guru Prasath, Chandramohan)...... 125 Mixing zone analysis of brine wastewater disposal from desalination plant at Kadmat, Lakshadweep Islands (U.S.Panda, D.Shyamala Varthini, S.K. Raju, Anirban Das, M.V. Ramana Murthy)...... 126 Impact of assimilating satellite derived sea surface salinity data from SMOS, Aquarius and SMAP in a high resolution ocean circulation model for the Tropical Indian Ocean: An Observing System Experiment framework (Smitha Ratheesh, Neeraj Agarwal, Rashmi Sharma)...... 127 Implementation of NEMO based high resolution regional coupled model at the National Center for Medium Range weather Forecasting (NCM- RWF) (Akhilesh K. Mishra, A. Gupta, I. M. Momin, A. K. Mitra, J. M. Castillo, H. Lewis)...... 128 Study of large-scale Atmospheric convection over the tropical Indian Ocean and its association with Oceanic variables. (Supriya Ovhal)...... 129 Observed inter-annual variability of temperature inversions over northern Bay of Bengal: the role of Indian Ocean Dipole (Antony P. Thomas, V. Suneel, Alex M.J., V. Trinadha Rao)...... 130 Characteristics of mesoscale eddies in the Bay of Bengal using a numerical model (Navin Chandra, Vimlesh Pant )...... 131 An improved nearshore bathymetric data from synergistic application of active and passive satellite remote sensing and machine learning (Surisetty V. V., Arun Kumar )...... 132 Role of ocean-atmosphere in the recent changes in cyclone activity in the north Indian Ocean (Vineet Kumar Singh, M.K. Roxy , Medha Desh- pande , G. Mano Kranthi , R. Emmanuel and R. Harikrishnan)... 133 Anomalous variation of sea surface temperature and air temperature in coastal North Indian Ocean in 2020: Examining the role of Covid-19 lockdowns (Samar Kumar Ghose, Sthitapragya Ray, Imran Nawab, Debadatta Swain)...... 134 CONTENTS 19

Intense upwelling in the southeastern Arabian Sea during the post-monsoon season (Anoopa Prasad C., Martin V. Mathew, K. N. Navaneeth, K. Jossia Joseph, R. Venkatesan)...... 135 Sound speed variation in the coastal waters of Kochi and signature of subsurface maxima (Abdul Azeez S)...... 136 Dinoflagellate cyst distribution along the Karwar coast: a HAB perspective (Prerana Shet , Priya M. D’Costa , Ravidas Naik , Shramik Patil , Mandar Nanajkar , Pranay Sawant , Kaustubh Warde , Shivakumar Haragi)...... 137 A study on the seasonal variation of nearshore waves along remote islands of UT Lakshadweep, West Coast of India (D. Shyamala Varthini, S.K. Raju, M.V. Ramana Murthy)...... 138 Source and Fate of Anthropogenic Particles in a Transitional Environment from Southwestern India (Gokul Valsan, Amrutha K, Lino Yovan, Santhosh Prabhu, Amrish V Narayan and Anish Kumar Warrier).. 139 Influence of sea breeze-land breeze circulation on thermodynamic parameters over Kochi, a coastal tropical station (Linsha C. L, Hamza Varikoden, Vishnu R)...... 140 Physical settings and biogeochemical response of oceanic front along the coastal waters off Mangalore, West Coast of India (Vishnu Narayanan Nampoothiri S., Sudheesh V, Kausar Fatima Bepari, Bikram R., Rasheed K., Anil Kumar Vijayan, G.V.M. Gupta)...... 141 Warming driven early blooming scenarios in North Eastern Arabian Sea (Midhun Shah Hussain, Smitha B. R., A. A. Mohamed Hatha).... 142 Coastal Risk Assessment of Alappuzha district in Kerala, India (Unnikr- ishnan K, M. K. Roxy)...... 143 Influence of low Saline Pool on the Upper Layer Dynamics of the South Eastern Arabian Sea (Muhammad Shafeeque, Vishnu Narayanan Nam- poothiri S., Smitha B. R., Kusum Komal Karati, Rasheed K., Asha Devi C.R., Hashim Manjebrayakath)...... 144 Modulation of boundary layer parameters in association with tropical cyclones over the Bay of Bengal (Arjun S. Nair, Hamza Varikoden, Vishnu R)...... 145 Spatio-temporal variations in the current pattern associated with Oceanic South Eastern Arabian Sea (Arun V S, Smitha B. R.)...... 146 Climatological Characteristics of Atmospheric Parameters during the Rapid Intensification of Tropical Cyclones over the North Indian Ocean (Thatiparthi K, Ambily Thankachan, Reshma M. S, K. S. Singh, Sub- bareddy Bonthu, Prasad K. Bhaskaran)...... 147 Performance of Atmospheric-Ocean Coupled Model in the prediction of Rapid intensification of Super Cyclonic Storm Amphan over the North Indian Ocean (Reshma M S, Ambily Thankachan, Thatiparthi K, K S Singh, Subbareddy Bonthu, Prasad K. Bhaskaran)...... 148 Wind-Wave Relationship Considering Local and Remote Wave Effects from Moored Buoy Measurements in the South-East Arabian Sea (M. Kalyani, K. Jossia Joseph, R. Venkatesan)...... 149 CONTENTS 20

Phenology of Coastal Upwelling in the South Eastern Arabian Sea (Shirin Jadhav, Muhammad Shafeeque, Smitha B. R.)...... 150 Inter comparison of underwater acoustic properties derived from diﬀerent reanalysed products and in situ observations in the South Eastern Arabian Sea (Maheswaran P A, Harikrishnan M, Satheeshkumar S, Varkichen Joy)...... 151 Thermohaline and acoustic characteristics of the Srilanka Dome during July 2019 (Dominic Ricky Fernandez, Raju R. P., Varkichan Joy, Niji T. Y.)...... 152 Characteristics of Diurnal Sea Surface Temperature Variability in the North Indian Ocean and its Implications to Air-Sea ﬂuxes (M. V. Martin, K. N. Navaneeth, C. Anoopa Prasad, K. Jossia Joseph, R. Venkatesan)153 On the Variability of Arabian Sea Mixing and its Energetics (Singh Shikha , Vinu Valsala, A G Prajeesh, Sridhar Balasubramanian)...... 154

Marine Geology and Geophysics (MGG) 155 Boron isotope study of foraminiferal carbonate from the Arabian Sea (An- jana Gireesh S, Mohd. Tarique, Waliur Rahaman)...... 157 Intensification of Oyashio Current as ‘Possible Cause’ for Reduction in the Western Pacific Warm Pool during last 1 My: Planktic foraminiferal evidences from the Sulu Sea (Vikram Pratap Singh, Ashutosh K. Singh, Devesh K. Sinha)...... 158 Mg/Ca of marine carbonates as a paleotemperature proxy: A case study of the southeastern Arabian Sea for the past 40Kyrs (Tejeswar Dash, Manish Tiwari)...... 159 Southern Ocean link to Indian Monsoon Variability during the last Glacial Period (Vikash Kumar, Manish Tiwari)...... 160 South Asian Summer Monsoon variability during the Mid-Piacenzian Warm Period (Sarathchandraprasad T , Manish Tiwari)...... 161 Denitrification and hydrographic variability during Mid-Pleistocene Tran- sition: Results from IODP Expedition 355 (Shubham Tripathi, Man- ish Tiwari)...... 162 Importance of geomorphological characteristics in determining location suitability for setting up desalination plants (A. Baskaran, J. Vinoth Kumar, S. Karthikeyan, M. Prabhakaran, P. Chandramohan).... 163 Quantification of basin-level air-sea carbon dioxide exchange across the Mid Pleistocene Transition (I. V. Satya Chanakya, Sambuddha Misra) 164 Crustal architecture and tectonic evolution of the Western Ghats and status of the major tectonic Shear Zones of Southern Granulite Terrain (SGT), and their offshore extension: An Integrated Geophysical approach (Zeba Nezrin F. K, Ajayakumar P)...... 165 Reconstruction of Indian monsoon variability since last glacial maxima from the Bay of Bengal (Nayana V Haridas, Upasana S. Banerji, Maya K, D. Padmalal)...... 166 CONTENTS 21

Role of in-situ and Meteoric 10Be in Quaternary Glaciation, Marine Chronol- ogy and Paleomagnetic Reconstruction (Ravi Bhushan, Partha Sarathi Jena, Shivam Ajay)...... 167 Role of Weathering and Reverse weathering in Global Carbon cycle (Juzer Shaikh)...... 168 Paleoclimate variability and global teleconnection during Northgrippian- Meghalayan stages from the Southern India (Upasana S. Banerji, Jithu Shaji, Maya K, A.K. Sudheer, Ravi Bhushan, D. Padmalal).. 169 Paleoclimate and Sea-Level Variability during Holocene epoch from Coastal Lowland Sediments of Kerala, SW India (Jithu Shaji, Upasana S. Banerji, Maya K, Kumar Batuk Joshi, Ravi Bhushan, D. Padmalal). 170

Ocean Engineering and Technology (OET) 171 Optimization of Floating Offshore Platforms for Wind Energy in Indian Coast (Arya Thomas)...... 173 Experimental study on the Maneuvering of a Container Ship in Regular waves (Rameesha T V, P. Krishnankutty)...... 174 Variability and distributional analysis of extreme swell wave energy flux in the Indian Ocean (S Sreelakshmi, Prasad K Bhaskaran)...... 175 Physical model studies on damage and stability analysis of breakwaters with double layer GSC armour units (Reshma George V )...... 176 Real-Time Estuary Observatory System for Monitoring Bhavanapadu Es- tuary by Utilizing Internet of Underwater Things (Teppala Vikranth, S.S.V.S. RamaKrishna, R. Srinivasan)...... 177 Variability and accuracy in the estimation of sound speed in Indian waters (Akhil Varghese, Anand P., Raju R. P.)...... 178 Air Quality Monitoring from Deep Ocean Moored buoy systems in the Indian Ocean (B.Kesavakumar, G.Vengatesan, M. Arul Muthiah, R. Venkatesan)...... 179 Experimental studies on coastal dyke made of geotextile sand Containers with coarse aggregate as bedding, core & secondary Layers (P. Vijay Charles, T. Nasar)...... 180 Ocean observation buoy powered using wave energy (Ashwani Vishwanath, Biren Pattanaik, Purnima Jalihal, K. S. Sajeev, Y. V. N. Rao, A. Karthikeyan)...... 181 Comparison of Vector Sensor Array Processing algorithms for Underwater Source Localization (Shweta Lokhande, G. Latha, S. Srinivasan, A. Malarkodi)...... 182 Effect of Mooring Motion on Temperature Profile Measurements in OMNI Buoy Systems: A Case Study (Biswajit Haldar, Abhishek Tandon, K. Jossia Joseph, M. Arul Muthiah, P. Senthilkumar, R. Venkatesan).. 183 Soundscape in Summer in Kongsfjorden, Arctic (Sunil Kumar Mohanta, G. Latha, M.C. Sanjana, E. Arunbabu)...... 184 Internal tide energetics in the Andaman Sea (B. Yadidya, A. D. Rao, G. Latha)...... 185 CONTENTS 22

Wave spectral characteristics of Two concurrent Cyclones Kyarr and Maha in the Arabian Sea (R. Keerthivasan, G. Latha, R. Balamurugan , R. Venkatesan)...... 186 Erosion and accretion pattern and shoreline change near Gopalpur port, East coast of India (P.K. Kar, P.K. Mohanty, B. Behera, S. Pradhan, S. Barik)...... 187 Sustainable production of marine pre-biotic (Polysaccharides and oligosaccharides) using microbial enzymes- future prospects (Victor Ndilipunye Haimbala)...... 188 Wave spectral characteristics in shallow waters off Goa coast during pre and post monsoon seasons (Reddy Janakiram, G. Latha, R. Balamurugan, R. Venkatesan)...... 189 Understanding the Pressure Measurement in multi-phase of Open Cycle OTEC power Plant (Y. V. N. Rao, Biren Pattanaik, Purnima Jalihal)190 Longterm shoreline changes along Kanyakumari coast using Geo spatial techniques (N. Rama Krishnan, J. Guru Prasath, P. Chandramohan) 191 Impact of future climate scenarios on Chloride ingress and Carbonation levels in coastal reinforced concrete structures (B Santosh kumar, S A Sannasiraj, K Murali )...... 192 Study of wave spectral characteristics in deep water region in the southern Bay of Bengal (R. Janani, G. Latha, M. Krishnaveni, R. Venkatesan) 193 Importance of Tide Gauge Observations to Identify the Multi-scale Sea Level Variability over Western Bay of Bengal (Arkaprava Ray, Sami- ran Mandal, Sourav Sil)...... 194 Shoreline changes of Devaneri coast, Tamilnadu, India (J. Sriganesh, A. Pradeep, S.A. Sannasiraj, V. Sundar)...... 195 Challenges in Design of Intake Structure in Remote Islands (Suganya S, Mounika Mallela, Preethi Sekar, Satya Kiran Raju Alluri, M. V. Ra- mana Murthy)...... 196 Monopile Supported Trestles for Intake and Outfall Systems at Remote Islands (Sondi Sudheer, Suganya S, Mekala Madhu, Maddu Sagar, Satya Kiran Raju Alluri, M. V. Ramana Murthy)...... 197 Performance of Monopile Platforms during Service Life (Mounika Mallela, Preethi Sekar, Satya Kiran Raju Alluri, Rajesh Katyal, M. V. Ra- mana Murthy)...... 198 A statistical study of seasonal underwater noise as a function of wind and marine traffic (Elizabeth shani N. X., Nimmi R. Nair, R. P. Raju, R. Sajeev)...... 199 Seasonal sediment characteristics analysis of Kandla creek and Gulf of Kutch (D. Nandhini, J. Sriganesh, K. Murali)...... 200 Conductivity sensor for marine applications based on capacitive coupling technique (Srinivasan R., Boby George, Tata Sudhakar and Ramadass G. A.)...... 201 Development of Autonomous Underwater Profiling Drifter (Muthvel P., Sarojani Maurya, Tata Sudhakar)...... 202 CONTENTS 23

Sensitivity analysis of wave hindcasts for the design criteria for engineering applications (Muhammed Naseef T, J. Rajkumar, Basanta Kumar Jena)...... 203 Design and Development of automatic open sea hybrid submerged fish cage system (S Muthukumaravel, V Gowthaman, J Santhanakumar,S Rajaguru, G Dharani)...... 204 Performance of C Profiler during the sea trial (V Gowthaman, G Shiva Prasad, Tata Sudhakar)...... 205 Effect of internal tides on acoustic propagation in the Central Arabian Sea (Merin C. A., Nimmi R. Nair, AnilKumar K.)...... 206 Numerical study of wave transmission and interaction with submerged artificial reef at Puducherry coast (Satya Kiran Raju Alluri, Ramana Murthy M V, Sannasi Raj S A)...... 207

Polar Science & Cryosphere studies (PSC) 208 Assessing the status of glaciers in upper Jhelum basin of Kashmir Hi- malayas using Sentinel–2 earth observation data (Syed Towseef Ahmad)210 Inventory and spatio–temporal dynamics of glacial lakes in Dibang river basin of Eastern Himalayas using combined approaches of Remote Sensing and GIS (Rayees Ahmed)...... 211 Sincere Feeding and Utmost care to Brutal Cannibalism of Self Brood in South Polar Skua in Schirmacher Oasis, Antarctica (Shivaji P. Chavan)212 Upperocean mixing during austral summer in the Prydz Bay region of East Antarctica (Jenson V. George, Sabu P., Aditya Narayanan, N. Anilkumar)...... 213 Arctic sea-ice variability using an Earth system model (Suraj Ravindran, Vimlesh Pant, A. K. Mitra, Avinash Kumar)...... 214 Sea-ice in the Weddell Sea sector of West Antarctica: Insights from ocean- atmospheric forcing (Juhi Yadav, Avinash Kumar, Rahul Mohan).. 215 Mixotrophic plankton population and Synechococcus distribution in waters around Svalbard, Norway during June, 2019 (Jane T Bhaskar, P.V. Bhaskar, Shridhar Jawak , R Jyothibabu)...... 216 Inter-annual Variability Of Sea Surface Temperature in the Indian Sector Of Southern Ocean during the Austral Summer (Antony P Thomas, P. Sabu, Subeesh M.P)...... 217 Polar processing and Chemical ozone loss in the Exceptional Arctic winters of 2011 and 2020 (R. Roy, J. Kuttippurath, D. Ardra, P. Kumar, S. Raj )...... 218 Evaluation of Sea-Ice and Ocean forecasts for the Antarctic: An Inter- comparison between coupled model and stand-alone ocean model. (Saheed P P, Ashis K Mitra, Vimalesh Pant, Ankur Gupta, Imran Ali)...... 219 Five years of IndARC mooring- science and technology (Divya David T., Subeesh M. P., Kesavakumar B., Archana Singh, M. Ravichandran, Arul. Muthiah, R. Venkatesan)...... 220 CONTENTS 24

Signature of seasonal surface warm water core along the west coast of Svalbard, Arctic (S. M. Pednekar)...... 221 An updated trends of global sea ice condition in a warming world (Kshitija S., Babula Jena, C. C. Bajish, N. Anilkumar)...... 222

Mathematics in Ocean Science (MOS) 223 Evaluation of the best performing WaveWatch III model setup for the In- dian Ocean (Abhijith Raj, B. Praveen Kumar, P. G. Remya, Meenakshi Sreejith)...... 224 Cubic spline polynomial as input energy spectrum for determining the nonlinear energy transfer rates in a wave spectrum (Vaishnavi S., Prabhakar V.)...... 225 Sea Surface Temperature Projection for the Bay of Bengal under RCP8.5 using 1D PWP Model (Hitesh Gupta, and Sourav Sil)...... 226 Applications of AI/ML in Fish Biomass Estimation System (Srinivas Bolem, Nitesh Verma, Arathy Nair, Muthukumaravel S, Dharani G, Tata Sudhakar)...... 227 Assessment of CMIP6 models’ skill for tropical Indian Ocean sea surface temperature variability (Subrota Halder, Anant Parekh, Jasti S. Chowdary, C. Gnanaseelan, Ashwini Kulkarni)...... 228 A study of mixing and biological activity in the Arabian sea using Fi- nite Size Lyapunov exponents (Jai Kumar, Ravi Kamal Choudhary, Manikandan Mathur, Neeraj Agarwal, and Rashmi Sharma)..... 229 Using Machine Learning to Characterize Ocean Basins (Sapkal Mayur, Singh Shikha)...... 230

Author Index 245 PLENARY TALK CONTENTS

PLENARY TALK

PLENARY TALK BY HON. FELLOW

1 Marine Ecosystems and Biogeochemistry of the Ocean (MEBO)

Sessions’ Chairman

Prof. K.V. Jayachandran, Kerala University of Fisheries and Ocean Studies (KUFOS), Ernakulam, Kerala

Dr. C. Revichandran, National Institute of Oceanography (NIO), Kochi, Kerala

Dr T. Balasurbramaniam, Chettinad Academy of Research and Education (CARE), Kelambakkam, Tamil Nadu

Dr. Parthasarathi Chakraborty, Indian Institute of Technology Kharagpur, West Bengal

2 Marine Ecosystems and Biogeochemistry of the Ocean (MEBO)

Invited Talks

INVITED TALK 1: Are Indian coastal seas really polluted? - Myths and Eﬀects Dr. G.V.M. Gupta, Centre for Marine Living Resources & Ecology (CMLRE), Kochi

INVITED TALK 2: The importance of Geotracers Program and way forward Dr. Sunil Singh, National Institute of Oceanography (NIO), Goa

INVITED TALK 3: Importance of Biogeochemistry of Indian Ocean and way forward Dr. Vinu Valsala, Indian Institute of Tropical Meteorology (IITM), Pune Marine Ecosystems and Biogeochemistry of the Ocean

Analysis of microplastics in water samples collected from ﬁve sewage treatment plants of Kolkata QUICK ORAL Runkob Srimani1, Ravidas K. Naik2 OSICON2021/35 1 University of Calcutta, Kolkata; 2 National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Vasco-da-Gama, Goa

Microplastics has become a matter of concern across the globe. We know very little about the dire consequences of microplastics. In India we have started working on micro plastics but we need to do more on this topic. Countries surrounding the Indian Ocean creates a lot of mismanaged plastic waste, India is one of them. In India we don’t have adequate sewage treatment plant. In Kolkata less than 10% of the total sewage is treated through 5 sewage treatment plant. We have collected samples from all 5 sewage treatment plant and the data will be presented through the poster in OSICON 2021.

4 Marine Ecosystems and Biogeochemistry of the Ocean

Estimation and Identifcation of Microplastics & Heavy Metals Ingested by Fishes in Kerala QUICK ORAL Nithya Thulasidharan, C.R. Emil John, R. S. Sruthi Thalayappil, P. T. Mathew OSICON2021/36 Department of Marine Chemistry, Kerala University of Fisheries and Ocean Studies, Panangad, Kerala

Microplastics are ubiquitous in the environment and have been detected in a broad range of concentrations in marine water, waste water; fresh water environment. The permanent presence of MPs and heavy metals in the water bodies is considered a global threat to several marine animals. Ingestion of microplastics and heavy metals by fishes could be an emerging environmental crisis because of the proliferation of plastic and heavy metal pollution, in aquatic environments. The objective of my study was to quantify the occurrences and types of MPs and the accumulation and concentration of heavy metals ingested by fishes within several water bodies. Biochemical composition of five water bodies fish; Black shark, Mackerel tuna, In- dian mackerel, Emperor fish, Yellow cat fish, Giantdanio, Red bellied piranha, etc. were evaluated. Moisture, protein and ash content for the samples ranged between 65.78-75.50,21.87-29.43,0.96-2.067% respectively. We investigated the ingestion of microplastics and heavy metals in the fish of Vembanad Lake, Fort Kochi-Arabian sea, Periyar river and Muvattupuzhayar, and pond sample. Overall, 15 samples were collected from 5 sites and processed for micro plastic identification by alkaline digestion and heavy metals by acid digestion method Identification of the polymer components of MPs was done using FTIR. Most of the fish samples were contaminated by microplastics, reflecting a high level of microplastic pollution. MPs were recovered from all the samples indicating their extensive distribution in the Arabian Sea comparable to lake and river. Among all the polymers analyzed based on FTIR spectra indicating that the ingestion of microplastic particles by fish are primarily human induced and discharged from different sources like cosmetics, personal care products, plastic bottles, washing clothes followed by polymer manufacturing and processing industries. We examined the adsorption of four heavy metals, cadmium (Cd), zinc (Zn), chromium (Cr) and lead (Pb). Identification of heavy metals was done using AAS. The subjected fish were exposed to heavy metals at sub lethal levels. Heavy metals accumulate in fresh water and elevate through food chain and fishes are badly affected because they are top consumer in aquatic systems which also posed a significant risk to human living.

5 Marine Ecosystems and Biogeochemistry of the Ocean

Estimation and Identifcation of Heavy Metals in Seawage Water QUICK ORAL Gowathamy Satheesan, K. K. Darsana, R. S. Sruthi Thalayappil, P.T. Mathew OSICON2021/37 Department of Marine Chemistry, Kerala University of Fisheries and Ocean Studies, Panangad, Kerala

Water is polluted in many different ways. Heavy metal is one of the most important pollutants in water. Heavy metal refers to any metallic chemical element that has a relatively high density and is toxic or poisonous at low concentrations. Increasing quantity of heavy metals in our resources is currently an area of greater concern, especially since a large number of industries are discharging their metal containing effluents into fresh water without any adequate treatment. This kind of water pollution, especially in higher concentrations, can cause severe health problems in humans and other organisms, including death. The most common heavy metal pollutants are arsenic, cadmium, chromium, copper, nickel, lead and mercury. Water sources (groundwater, lakes, streams and rivers) can be polluted by heavy metals leaching from industrial and consumer waste; acid rain can exacerbate this process by releasing heavy metals trapped in soils. Long-term exposure to these heavy metals from drinking-water can cause cancer, kidney diseases, vomiting, diarrhea, stomach cramps and nausea. This study aims to determine the heavy metal concentration of different types of water bodies in different locations and ways to remove them. Water samples were collected from five different water bodies, they include pond (Kottayam), lake (Vembanad) ,canal (Tripunithura), river (Periyar), and sea (Fort Kochi). The reason for choosing these places is because of the high level of pollution there. The highest concentration of heavy metal can be seen from Vembanad lake. This is due to the dumping of inorganic wastes from houseboats into the lake. Several methods have been used to remove heavy metals from contaminated water. They include chemical precipitation, ion exchange, adsorption,membrane filtration, reverse osmosis, solvent extraction, and electrochemical treatment. But we are try- ing to remove heavy metals in a more eco-friendly and more cheaper way. For that we use chitosan. Chitosan is a sugar that is obtained from the hard outer skeleton of shellfish, including crab, lobster and shrimp. Chitosan was found to be effective in removing metal ions Cu, Zn, Fe and Cr from industrial effluents.

6 Marine Ecosystems and Biogeochemistry of the Ocean

Did COVID-19 impact the Net Primary Productivity in the Arabian Sea? QUICK ORAL Sunanda N., Jayanarayanan Kuttippurath, Arun Chakraborty, Rony Peter OSICON2021/41 Centre for Oceans, Rivers, Atmosphere and Land Sciences Indian Institute of Technology, Kharagpur, West Bengal

The worldwide spread of the contagious Severe Acute Respiratory Syndrome (SARS) COronaVIrus Disease (COVID) 2019 had forced countries to go into nationwide lockdown in 2020. To assess the impact of lockdown on Net Primary Productivity (NPP), we make use of satellite and reanalysis datasets. The distribution of Aerosol Optical Depth (AOD), Chlorophyll-a (Chl-a), Sea Surface Temperature (SST) and 10 m winds over the Arabian Sea during the pre-Lockdown (01 January 2020 - 24 March 2020), lockdown (25 March 2020 - 08 June 2020) and post-lockdown (8 June 2020 - 30 June 2020) was analysed and was compared with the climatology. The spatial distribution of AOD, NPP, Chl-a and SST during these periods and temporal analysis of NPP with respect to AOD, SST and wind stress over the Arabian Sea are analysed and will be presented. Preliminary analysis suggests that there is a decrease in NPP, which is complemented with an increase in SST and a decrease in AOD during 2020, and these are likely due to lockdown. Although oceanic warming can inﬂuence the NPP in AS, the anomaly of NPP in 2020 shows a decline in its magnitude; suggesting the impact of lockdown on NPP there.

7 Marine Ecosystems and Biogeochemistry of the Ocean

The Role of Organic Nutrients on the Sustainability of Primary Production in the Bay of Benagal QUICK ORAL Sreevidhya R OSICON2021/43 Kerala University of Fisheries and Ocean Studies, Kochi, Kerala

The concentration of dissolved inorganic nutrients is close to detection limits in the mixed layer due to strong stratification in the Bay of Bengal. The low primary production is reported in the Bay, with limited data, and attributed to low nutrient concentrations. We hypothesize that organic nutrients may contribute significantly to the primary production in the Bay of Bengal. In order to examine the same, the spatial variations in organic and inorganic nutrients were measured in Bay of Bengal and its impact on primary production is investigated. The western Bay of Bengal is found to be a low productive region with oligotrophic conditions and highly stratified water column is noticed in the upper 20 m of water column in the northern Bay. Occurrence of cyclonic and anticyclonic eddies were found in the study region with relatively higher nutrients concentrations in the former than latter region. The concentration of dissolved organic nitrogen (DON) and dissolved organic phosphorus (DOP) were an order of magnitude higher than dissolved inorganic nitrogen and phosphorus. The DON contributed 70– 99% oftotal dissolved nitrogen (TDN). Relatively higher DON concentrations were observed in the northern Bay of Bengal associating with low salinity and displayed inverse relation between salinity and DON indicating with possible source from rivers. The uptake rates of DON by phytoplankton suggested that DON uptake rates are 10 times lower than Dissolved inorganic nitrogen (DIN) in the Bay of Bengal. The linear relationship observed between organic nutrients (DON and DOP) and primary production earlier and significant uptake rates found in this study suggests that organic nutrients are used as an alternative source of nutrients by phytoplankton in the Bay of Bengal. The composition, nature of organic nutrients and phytoplankton composition determines the uptake rates and more focus needs to be paid in future.

8 Marine Ecosystems and Biogeochemistry of the Ocean

Monitoring of farmed shrimps (Penaeus vannamei) from Nagapattinam region of Tamil Nadu, India for Salmonella contamination QUICK ORAL Akalesh, Geevaretnam Jeyasekaran, Robinsondhas Jeya Shakila, Theivasigamani OSICON2021/45 Anand Department of Fish Quality Assurance and Management, Fisheries College and Research Institute,Thoothukudi, Tamil Nadu, India

This study investigated the occurrence of Salmonella in farmed shrimps (Penaeus vannamei) located at Nagapattinam region of Tamil Nadu, India. Shrimp, water, sediment, biofloc, feed, and probiotics samples (157 Nos.) collected from April 2018 to July 2019 during one culture cycle and also water and sediment samples (188 Nos.) collected from 23 natural creeks, which provide source water to shrimp farms, during December 2018 to April 2019 were examined for the prevalence of Salmonella spp. by conventional and molecular methods. The Salmonella isolates were tested for the antimicrobial resistance by disk diffusion assay against the al- legedly used antibiotics in shrimp farms such as sulfonamide (SF), tetracycline (TC), chloramphenicol (CAP), and furazolidone (FZ). The antibiotic resistant strains were sequenced and identified by BLAST analysis. The incidence of Salmonella in the tested samples was 27.3% by conventional method, and 8.2% by molecular method in shrimp farms, and 28.7% of water and 25.5% of sediment samples from natural creeks were positive for Salmonella spp., while molecular test gave positive results for 7.44% and 5.15% of the creek water and sediment samples, respectively. All the Salmonella isolates were resistant to sulfonamide (SF), but sensitive to tetracycline (TC), chloramphenicol (CAP), and furazolidone (FZ). The PCR amplification of mitochondrial 16S rRNA region identified the Salmonella serovars as Salmonella serovar Montevideo and Salmonella serovar Enterica. The serovar S. Montevideo has been found highly resistant to the tested antibiotics and it is the emerging food- borne human pathogen, and reported for the first time in India. The incidence of antibiotic-resistant serovar S. Montevideo in the water samples of natural creeks that supply water to the shrimp farms emphasizes the need for greater regulatory steps to control its prevalence.

9 Marine Ecosystems and Biogeochemistry of the Ocean

Assessment of Formaldehyde over the Indian Ocean and its impact on the Marine Environment QUICK ORAL Gopikrishnan G. S1, Jayanarayanan Kuttippurath2 OSICON2021/46 1Department of Physical Oceanography, Kerala University of Fisheries and Ocean Studies, Panangad, Kochi; 2Coral, Indian Institute of Technology Kharagpur, West Bengal, India

Atmospheric formaldehyde (HCHO) is a potential pollutant and very harmful to public health at higher doses. There are different sources for HCHO in the atmosphere, in which fuel combustion and biomass burning is predominant. The oxidation of hydroxyl radicals (OH) and methane are the chemical production pathways of HCHO in the troposphere. Here, we show a different source of HCHO emission to the atmosphere; the maritime shipping. The analyses using satellite measurements for the period 2005–2014 reveal large amounts of HCHO release along the ship routes in Indian Ocean, about 7-8 × 1015 molec./cm2 . This is nearly twice (150–200%) the ambient or background HCHO levels (about 4 × 1015molec./cm2), when there is no ship emissions in the north Indian Ocean. The trend in HCHO concentrations over the Indian Ocean sea routes is about 0.008 × 1015 molec./cm2/year. The amount and the increasing trends of HCHO over the maritime routes in the north Indian Ocean are also comparable to those of the busiest sea–lanes in the world Oceans, such as the Panama Canal, Mediterranean Sea and Strait of Malacca. The observed HCHO pattern agrees qualitatively well with the results from the Chemical Trans- port Model, GEOS CHEM. We have also found a significant deposition of HCHO over the ocean surface along the shipping lanes. Our analyses, henceforth, suggest use of a better fuel for shipping to reduce the maritime pollution, as the polluted air can often be transported to the coastal regions and islands, which is a concern for public health as well as the ocean wealth in those regions.

10 Marine Ecosystems and Biogeochemistry of the Ocean

Understanding the distribution of plastics in lower Ganga basin and their fate in river & marine waters ORAL OSICON2021/59 Gopala Krishna Darbha Department of Earth Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, India

Although India is one of the major plastic-waste-generating countries, few studies have been conducted on microplastics (MPs) in freshwater systems that are key contributors to oceans. The current study explores MPs in sediments and water that were collected at five major cities across the Ganga River. MPs number and mass density range in sediment were found to be 17 to 36 items/kg dry weight (d.w.) and 10 to 45 mg/kg d.w. of sediments, respectively, while in the water sample, they were 380 to 684 items/1000 cubic metre and 143 to 340 mg/1000 cubic metre, respectively. Overall, white color and film-shaped MPs were the major contributors in all samples. MPs of 2.5–5 mm size contributed to a greater number and mass as compared to other fractions. Polyethylene was found to be a widely distributed plastic-type reflecting its high usability. In addition, the MPs undergo degradation to produce finer plastics particles called as nanoplastics (NPs). The stability of NPs in marine and river waters ascertains their availability for the uptake by aquatic organisms or to assess their property to act as vector to transport co-contaminants. We present our recent results published in understanding the stability and transport properties and toxicity of NPs in river and marine waters that determines their ability to associate with toxic metals, metal oxide nanoparticles and other pollutants such as poly aromatic hydrocarbons.

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Microplastics in Marine and Freshwater System: A Review on Micro plastics and Heavy Metals Accumulation on Fishes QUICK ORAL C. R. Emil John, Nithya Thulasidharan, R. S. Sruthi Thalayappil, P. T. Mathew OSICON2021/63 Department of Marine Chemistry, Kerala University of Fisheries and Ocean Studies, Kochi

Microplastics are ubiquitous contaminants that could harm marine ecosystems. Here, the study investigates the amount of microplastic particles in marine water and fresh water bodies also provide to information on content of microplastics and concentration of heavy metals in marine fishes and fresh water fishes. We investigated the ingestion of microplastics and heavy metals in the fish of Vembanad Lake, Fort Kochi-Arabian Sea, Periyar river and Muvattupuzhayar, and pond sample. Overall, 15 samples were collected from 5 sites and processed for microplastic identification by alkaline digestion and heavy metals by acid digestion method Identification of the polymer components of MPs was done using FTIR. Moisture, protein and ash content for the samples ranged between 65.78-75.50, 21.87 -29.43, 0.96-2.067% respectively. In marine and freshwater fishes MP particles can pass the gastroin- testinal tract wall and bioaccumulation could arise when uptake exceeds release or when particles are assimilated in muscles or organs. The effects of accumulation may be significant, especially in long-living species, with implications for food web transfer and fish as food items. The trace metals and heavy metals level of fish samples were measured by AAS. There were great variations among heavy metal levels in the muscles of the fifteen fish samples. MPs and heavy metals can cause various Eco toxicological effects on fishes like behavioural change, neurotoxicity effects and cytotoxicity etc. Our study finds that there is a paucity of information on the accumulation of MPs by marine and freshwater fishes and there are very few studies on its effects also there is a debate whether this accumulation is subjected to the bio-magnification process which ultimately affects human life. These findings and other published in the literature raise concern regarding high level predators and humans consuming fish being exposed to MPs, heavy metals, and high light the need of more research on the topic

12 Marine Ecosystems and Biogeochemistry of the Ocean

Assessment of seasonal cycle of physical and biological variables from CMIP6 ocean biogeochemistry models over the tropical Indian Ocean QUICK ORAL Biswarup Bhattacharya, Sachiko Mohanty, Charu Singh OSICON2021/64 Indian Institute of Remote Sensing, ISRO, Dehradun 248001, Uttarakhand, India

Under the global climate change scenario, the ever-increasing ocean temperature and elevated concentration of CO2 in the ocean, as well as the atmosphere, im- part a significant effect on ocean biogeochemistry. The partial pressure of CO2 in surface water of the oceans depends on the ambient physical and biological properties of the region and its variability. In the present study, the ability of Coupled Model Inter-comparison Project phase 6 coupled biogeochemistry models in simulating the seasonal cycle of sea surface temperature (SST), surface chlorophyll concentration (Chl–a), nitrate, phosphate, and silicate are evaluated over the tropical Indian Ocean (IO), to quantify the physical- biogeochemical capabilities of each model. The historical simulations from 11 coupled climate models which include ocean biogeochemistry components are accessed. The simulations of CMIP6 models simulated SST are compared with the Extended Reconstructed SST for the period 1950-2014 and with the available RAMA buoy data. The model simulated Chl-a are compared with MODIS Aqua for the period 2003-2014 and nutrients are compared with World Ocean Atlas 2018 climatology data. A statistical validation carried out using the RAMA buoy SST data shows that all the models exhibit better performance in the case of the buoy located in the northern Bay of Bengal. The present analysis also suggest that all the models have difficulty in capturing the equatorial dynamics over the tropical IO. A comparison of bias estimates shows that the CESMs and CanESM5 models have better agreement with the observation over the BoB, equatorial ocean, and the Southern Ocean in all the seasons as compared to all other models. The ability of Earth System Models to accurately simulate the seasonal cycle of the physical and biological variables has important implications for projecting change in future ecosystem.

13 Marine Ecosystems and Biogeochemistry of the Ocean

Analysis of Water Quality of Samples Collected from Ernakulam, Alappuzha and Kottayam Regions, Kerala, India QUICK ORAL Darsana K. K., Gowthamy Satheeshan, R. S. Sruthi Thalayappil, P. T. Mathew OSICON2021/67 Kerala University of Fisheries and Ocean Studies, Kochi, Kerala

Water quality in water bodies is subjected to the natural degradation process of Eutrophication and has adverse impact on societal development. Most of the water bodies in Kochi, Alappuzha and Kottayam shrunk considerably due to the aggres- sive rapid urbanization process and uncontrollable encroachment. This study aims at assessing the water quality of various water bodies in and around Ernakulam district. A detailed study was conducted to determine the physico-chemical parameters of water of 5 diﬀerent water bodies in Ernakulam, Kottayam and Alappuzha named Periyar River, Fort Kochi beach, Poonithura Canal, Vembanadu Lake and ﬁsh farm from March to April, 2021. The selected parameters were water temperature, colour, salinity, pH, Dissolved Oxygen (DO), Total Nitrogen (TN) and Total Phosphorous (TP). For the samples taken, the temperature ranged from 29oC to 35oC, considerable variation of water colors were found, salinity ranged from 0 to 30 ppt (parts per thousand), Dissolved Oxygen (D0) ranged from 6.4 mg/L to 10.4 mg/L, TN ranged from 0.1µmol/L to 3.1µmol/L and TP ranged from 0.5µmol/L to 5.1µmol/L. This analytical study would enhance the socio eco features of these water bodies by implementing utility based restoration and development programs.

14 Marine Ecosystems and Biogeochemistry of the Ocean

Biophysical Control on Variability in Phytoplankton Production and Composition in the South-Western Tropical Indian Ocean during Monsoon ORAL OSICON2021/77 Sarat C. Tripathy1 , P. Sabu1 , Sivaji Patra2 , Ravidas K. Naik1, Amit Sarkar1,3, Vankara Venkataramana1 , Anvita U. Kerkar1 , P. Sudarsanarao1 1National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Goa 2National Centre for Coastal Research (NCCR), Ministry of Earth Sciences, NIOT Campus, Velachery, Chennai 3Environment and Life Sciences Research Centre, Kuwait Institute for Scientiﬁc Research Centre, Al-Jaheth Street, Shuwaikh

The existing oligotrophic conditions in the southwest tropical Indian Ocean (SWTIO) is believed to be one of the causes for low phytoplankton productivity (PP) observed in this area. Though many remote sensing-based studies on PP have been carried out in SWTIO; studies on in situ estimation of PP and its cause(s) of variability are scarce. Thus, to understand the controlling environmental forcing on the variability in phytoplankton biomass (chlorophyll-a; Chl-a), community structure and productivity, time series (TS; 6h intervals for 10 days; 1 station) plus point measurements (RT; 3 stations) were carried out in the SWTIO during southwest monsoon (June) of 2014. Strong thermohaline stratification resulted in shallow (35-40m) mixed layer (ML). Subsurface Chl-a maximum (SCM) oscillated within 40-60m with majority of peaks at ∼50m, and existed just beneath the ML depth. Light availability during sampling period was highly conducive for algal growth; whereas nutrient ratios indicated N- and Si- limitation suggesting unfavorable conditions for diatoms and/or silicoflagellates growth within the ML. Furthermore, HPLC-based pigments analysis confirmed dominance of nano-sized plankton (53%) followed by pico-plankton (25%) and micro- plankton (22%). Column-integrated production (IPP) varied from 176-268 (241±43 mgCm−2d−1 ) and was relatively stable, except a low value on 11-June, which was ascribed to the drastic drop- down in the daily incident PAR (19.4 E m−2 d−1 ) due to overcast sky. The Chl-a-specific PP (PB ) was mostly higher within the ML and showed no surface photoinhibition, due to the dominance of smaller phytoplankton (less prone to ”pigment packaging” effect) in the surface layer. Compara- tively, higher P B within the ML is indicative of phytoplankton healthiness during the observation period, whereas low P B below the SCM was due to light limitation. Highest integrated Chl-a (39 mg m−2 ) and IPP (328 mgC m−2 d−1) observed at RT-2 was clearly linked to low sea surface height anomaly (SSHA), cyclonic disturbance and associated positive Ekman suction. Conversely, high SSHA and strong stratification conditions prevailed at TS, RT-4 and RT-6 stations leading to relatively lower IPP at those stations.

15 Marine Ecosystems and Biogeochemistry of the Ocean

Interannual and spatial variability of bio-optical characteristics in the Indian sector of Southern Ocean during austral summer ORAL OSICON2021/83 Sudarsana Rao Pandi1, Sarat C. Tripathy1, S. S. Shaju2 ,P. Minu3, Anvita U. Kerkar1, Deepti V. G. Dessai1, C. C. Bajish1, N. Anilkumar 1 1National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Goa 2Centre for Marine Living Resources and Ecology, Ministry of Earth Sciences, Kochi 3ICAR-Central Marine Fisheries Research Institute, RC-Calicut

Studies on bio-optical properties, which play a key role in inﬂuencing the underwater light-ﬁeld and phytoplankton productivity (PP) have been extremely sparse in the Southern Ocean (SO) to date, leaving the Carbon cycle of the region unclear. Considering these lacunae, we present the interannual and spatial variability of the surface bio-optical constituents (i.e., Chlorophyll a

(Chl-a), light absorption by phytoplankton (aph (443)), detritus (ad (443)), coloured dissolved organic matter (aCDOM (443)), and associated hydrographic parameters in the diﬀerent frontal regions (divided into seven transects i.e., T1-T7) for three successive years (i.e., 2011, 2013, 2015) in the Indian sector of SO (ISSO) during austral summer. Vertical observations were carried out only during 2011 (T1-T3). We observed clear latitudinal, zonal and vertical variability in in situ bio-optical properties, the surface optical properties could be tested with satellite data products.

The aph(443) showed three distinguished signiﬁcant positive linear relationships with Chl-a for 2 three years. The strongest aph (443)-Chl-a relationship (R = 0.88, n = 106, p <0.0001) observed during 2011, which was used to derive aph(443) for others years, which held good for 2015 and moderately for 2013. The percent contributions of bio-optical constituents to the total absorption

(at= (aph(443)+ad(443)+aCDOM (443)) varied interannually showing a decrease in phytoplankton contribution and increasing contribution of CDOM and ad . A positive relationship between aCDOM (443) with Chl-a and a negative relationship with slope (S300−500 ) suggested that CDOM production was mainly due togrowth and decay of phytoplankton blooms. Using a global absorption model, based on aph(443) versus spectral slope of aph(S443−510 ), we could derive phytoplankton size-classes. The derived phytoplankton size-classes and their photo acclimation capacity were conﬁrmed by the mean blue (443 nm) to red (675 nm) spectral (B/R) ratio of aph spectra. The mean B/R ratios are decreasing with increasing phytoplankton size-class, which were 2.3, 2.9, and 3.2 for micro, nano and picoplankton, respectively. This study provides baseline data for bio- optical observations and would facilitate in understanding the underwater light-ﬁeld in relation to productivity, and synoptically derive phytoplankton size-classes using space-borne sensors in this remote and relatively inaccessible polar region.

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Microbial carbon pump: Reservoir for ocean carbon- future prospects for carbon sequestration ORAL OSICON2021/87 Lata Gawade1 ,Venkataramana Vankara2 1Dept. of Microbiology, Goa University-Taleigao Plateau- Goa 2National Centre for Polar and Ocean Research (MoES), Goa

Carbon is a key element in global biogeochemical cycles, thus playing a fundamental role in ocean processes. Oceans cover 70% area of the planet Earth thus playing an important role in shaping and controlling the planet’s climate. In the present ‘Anthropocene’, the long-term storage of carbon is the main concern, hence oceans can act as a major reservoir for carbon sequestration. Among three vertical carbon pumps that bring down atmospheric carbon into the oceans, biology plays a key role through processes like biological carbon pump (BCP) and the microbial loop (ML) in carbon fixation and mineralization as well as its transport from the surface to deeper oceans. The recently proposed microbial carbon pump (MCP) is one such conceptual framework to address the microbial role in the production of refractile dissolved organic matter (RDOM); an additional reservoir and path for long-term carbon sequestration within the ocean due to its refractory nature and hence long lifetime. It emphasizes the microbially mediated conversion of labile organic carbon to recalcitrant one. The MCP concept connects marine microbiology with marine biogeochemistry, assuming that the production mechanism of RDOM in the marine environment is mainly microbial where heterotrophic bacteria play a prime role. The majority of the RDOM production can be attributed to microbial activities due to the transformation of labile organic matter to RDOM, direct exudation from planktons, microbial preferential utilization of biomolecules. MCP is assumed to regulate the carbon gradient between RDOM with an average life of less than 100 years (short- lived) and more than 100 (long-lived) years. Approx. 94% of DOC in the ocean is refractory. Due to its refractory nature, RDOC can persist in the ocean for up to 4000-6000 years. The Global Ocean contains a huge RDOM pool of 624 Gt C which is nearly equal to the CO 2 pool (750 Gt C) in the atmosphere. Changing global climatology and rising ocean temperature will significantly influence the functioning of the BCP and MCP. Therefore, the processes involved in the formation and existence of the RDOM pool have important implications for the ocean carbon cycle and global climate.

17 Marine Ecosystems and Biogeochemistry of the Ocean

Inter-annual variability of zooplankton assemblages in the Indian sector of the Southern Ocean ORAL OSICON2021/89 V. Venkataramana, R.K. Mishra, Anvita U. Kerkar, N. Anilkumar National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Vasco-da-Gama, Goa

Due to its remote location, zooplankton diversity, biomass and abundance are still poorly known in the Indian sector of the Southern Ocean (SO). Despite its importance, a systematic zooplankton sampling has been made in various expeditions in the Indian sector of SO, with particular reference to Copepoda. Data were collected between January and February on a repeated transect along 57oE, examined various oceanographic locations from the central Indian sector of SO (east of the Kerguelen Plateau) to coastal Antarctica. Both multi plankton and Bongo net survey was ac- customed in the study region for zooplankton monitoring. Consequently, copepods were significantly contributed to the total zooplankton biomass in both the bongo net and multi plankton sampler across the entire study region. Relatively, high zooplankton abundance was observed in the Polar Front (PF) than the Subtropical and Subantarctic Fronts. South of the PF, the copepods were numerically dominated by Calanus propinquus, Calanoides acutus and Oithona spp., while north of the front the zooplankton community was dominated by the copepods Clauso- calanus spp., Ctenocalanus citer, Calanus simillimus and Oithona spp. A total of 32 species of zooplankton were encountered during the study period. Four copepod species were identified, characterized by ecological niche which were strongly correlated with oceanographic fronts, demonstrating both biogeographic importance and oceanographic conditions. The highest zooplankton grazing impact was recorded in the PF zone where zooplankton removed ∼81% of the dailyphytoplankton production, while north of the PF zooplankton grazing was generally low. Therefore, this study suggests that the spatial and vertical distribution of zooplankton abundance and species composition were chiefly driven by physical and biological conditions in the Indian sector of the SO.

18 Marine Ecosystems and Biogeochemistry of the Ocean

Factors controlling the Interannual variability of Particulate Organic Matter Characteristics in the Indian Sector of the Southern Ocean ORAL OSICON2021/103 Melena A. Soares1, N. Anilkumar1, P. Sabu1, V. Venkataramana1 , R. K. Naik1, R. K. Mishra1, R. Chacko2, A. Sarkar3 1National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Goa; 2MES college, Vasco-da-Gama, Goa, India. 3Kuwait Institute of Scientiﬁc Research, Safat, 13109, Kuwait.

Oceans contain large amount of organic matter that play an important role in the global carbon cycle, especially the particulate organic matter (POM). The Indian sector of the Southern Ocean (ISSO) is a dynamic region, with a strong frontal structure. This region experiences numerous short-term events, as well as seasonal changes that influence the POM dynamics in these waters. The present study was an attempt to understand the inter-annual variability of POM characteristics and the factors/processes controlling the inter-annual POM dynamics. To address this, seawater samples were collected from 7 depths at different locations across the fronts of the ISSO during austral summer 2012 and 2013. The samples were analysed for 13 the elemental carbon, nitrogen and δ C(POM) , along with other auxiliary chemical and biological variables. A significant variation was observed in the elemental com- 13 position of POM and δ C(POM) during the study periods. Overall, the POC was comparatively higher during austral summer 2013 (29.5 to 194.2 µg/L) compared to 2012 (15.1 to 74.6 µg/L), especially in the Subtropical frontal (STF) waters. Also, even though the POM attributes were highly variable at the STF region, the 13 δ C(POM) depleted from the STF(-21.4 to-24.05 ) towards the colder nutrient rich polar front (-25.65 to -26.00 ) in the surface waters. The significant difference in the POM characteristics, at the STF during the two study periods was possibly due to the eddy dynamics and associated changes in the nutrients and subsequently the biological community structure. Further, the statistical analysis of POC and 13 δ C(POM) with other biochemical variables, along with other POM proxies (C:N and POC:Chl-a) indicated the predominance of different tropic processes across the fronts of the ISSO. This study suggests the role of nutrient availability, dominant phytoplankton community and other heterotrophic activities, as the primary factors in controlling the variabilityof POM characteristics and dominant trophic processes inter-annually. Additionally, hydrographic factors like temperature, sea-ice cover, Mixed layer depth and eddy dynamics have a critical role in influencing the POM dynamics by altering the primary factors in the ISSO.

19 Marine Ecosystems and Biogeochemistry of the Ocean

Evaluate the Impact of marine pollution in the tourist beach Gopalpur, Bay of Bengal QUICK ORAL Debasis Rath, Mukunda Kesari Khadanga, Sheshdev Patro OSICON2021/115 Department of Marine Sciences, Berhampur University, Berhampur

Present study evaluates the marine pollution along Tourist beach of Gopalpur coast. Beaches provide protection to residents living near the ocean by acting as a buffer against the high waves and storms and helps to drive economic activities important to nearby communities. Gopalpur is one of the popular tourist beaches in Odisha along Bay of Bengal. Every year numerous visitors are attracted by the beauty of it. The high rise in tourism in the beach, threat of rise in pollution makes a great matter of concern for the coastal areas. Over use by visitors can damage sensitive habitats such as beach dunes and create marine debris. Water samples are collected three sites in the seasonal interval (pre-monsoon and post-monsoon) along the Gopalpur beach during 2019. The results are found that in post-monsoon the temperature (24oC) is minimum as compared to pre monsoon (28oC), DO value (7.5 mg/l) is maximum in pre-monsoon as compared to post-monsoon (7.15 mg/l), TSS value (26.2 mg/l) is minimum in pre- monsoon and maximum in post-monsoon (35.06 mg/l), BOD value 1.6 in pre monsoon and 1.1 in post monsoon during the study period respectively. Similarly, the nutrients were found (NO2C 0.3µmol/l, NO3 1.5 µmol/, 4 NH4 1.21 µmol/, PO 1.2 µmol/l and SiO4 4.8 µmol/l) higher in post-monsoon and lower in pre-monsoon because of the outlet flow of aquaculture industries and the water flow from river increase the nutrient contents in sea, which causes the high level of pollution in the sea. Marine pollutants are the ingestion, suffocation and entanglements of hundreds of marine faunae. Ecological consequences the pollution in coastal waters impact to the heath of biodiversity, habitat, and ecological processes. It can damage entire food chain directly or indirectly. The polluted beach water makes swimmers sick and can be a cause of economic decline for the coastal inhabitants. To prevent pollution, we must have to change the unhealthy practices, awareness and obey the rules and regulations in the coastal areas.

20 Marine Ecosystems and Biogeochemistry of the Ocean

Spatial and seasonal trends of trace metals in the surfacial Sediments from oﬀ Kochi - Geochemistry and Environmental Implications QUICK ORAL Princy M John1, Vishnu Murali2, Priya Varghese2, Anu Gopinath2 OSICON2021/123 1School of Ocean Science and Technology, Kerala University of Fisheries and Ocean Studies, Kochi; 2Department of Aquatic Environment Management, Kerala University of Fisheries and Ocean Studies, Kochi

Thirty sediment samples representing pre and post-monsoon seasons were collected along a transect from off Kochi, lying between the latitudes 9o57’59.5”- 9o54’30.4” and longitudes 76o11’7.04”-75o38’50.3” of the South eastern Arabian Sea. The present study investigates the levels of trace metals (Zn, Cd, Pb, Cu, Fe, Ni, Mn, Co, Cr and V), total organic carbon (TOC) and grain size to assess the extent of environmental pollution and to discuss the distribution of these trace metals in the surfacial sediments. The range of monthly average concentrations of trace metals in the pre and post-monsoon sediment samples of Southeastern Arabian Sea varied from Zn (28.77-39.95, 34.28-55.05 mg/kg), Pb (3.02-3.54, 2.8-3.08 mg/kg), Cu (4.34-11.07, 6.71-11.49 mg/kg), Fe (7895-9915, 9100-11116 mg/kg), Ni (18.55- 39.84, 41.18-82.71 mg/kg), Mn (65.87-86.97, 81.78-102.49 mg/kg), Co (3.55-5.4, 6.2- 6.64 mg/kg), Cr (48.93-99.89, 85.41-168.91 mg/kg) and V (51.03-63.68, 53.55- 76.46 mg/kg) respectively. Sediment pollution assessment was done using the Contami- nation factor (C.F), Geoaccumulation Index (Igeo), Enrichment Factor (EF), and Pollution Load Index (PLI). The results revealed that considerable contamination of Ni and Cr was detected in the coastal stations in January and February (2019). The Geoaccumulation Index indicated that the surface sediments of the off Kochi samples were moderately contaminated with Ni and Cr in the coastal stations (stns 1 & 2) in January-2019. The calculation of enrichment factors of various metals showed a significant enrichment with respect to Zn and Cr in Stations 2 and 3 during the month of January 2019. The Pollution Load Index values calculated for all the stations showed lower values than the baseline levels of contaminants. The majority of trace metals analysed in this study exhibited the highest concentrations at stations 1 and 2 where the land-based anthropogenic input was found to be maximum.

21 Marine Ecosystems and Biogeochemistry of the Ocean

Impact of Siderophore producing bacteria, iron, and dissolved siderophore on coccolithophore and diatom monocultures ORAL OSICON2021/124 Parli V Bhaskar1, Alok K Sinha1,2 , Jane T Bhaskar1 1National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Vasco da Gama; 2P.G. Centre, Chikka Aluvara, Somwarpeth Taluka, Mangalore University.

Bioavailability of siderophore bound iron in oceans may vary with phytoplankton species, influencing natural phytoplankton population. This hypothesis was tested in the laboratory on a coccolithophore Gephyrocapsa oceanic and a diatom Skele- tonema costatum. In the laboratory experiment, addition of siderophore producing bacteria increased the growth of only G. oceanica by 80 folds in flasks having only Desferrioxamine-B (Sid) and by more than 2-3 orders of magnitude in iron with siderophore (Fe+Sid) flasks. Although S. costatum also grew well in iron (Fe) and Sid amended medium with bacterial isolates (Fe + bac and Sid + bac), it’s growth was suppressed in flasks containing Fe+Sid+bacteria. Our findings show that phytoplankton growth in iron amended medium with siderophore and siderophore producing bacteria varies with species and iron bound to siderophores may play an important role in shaping the phytoplankton community structure and associated biogeochemical processes in Southern Ocean.

22 Marine Ecosystems and Biogeochemistry of the Ocean

Impact of heavy load nutrient on Seagrass growth in tropical environment: A review article QUICK ORAL Anil Kumar Behera, Mukunda Kesari Khadanga and Sheshdev Patro OSICON2021/132 Department of Marine Sciences, Berhampur University, Berhampur

The present study is to evaluate the impact of anthropogenic and industrial load for declining seagrass in the aquatic ecosystem. Seagrass play a vital role in a marine ecosystem, and also called ecosystem engineers as they provide many ecosystem services. It was maintaining water quality, prevents sediment erosion by atten- uating wave actions, helps in carbon sequestration, provides nursery ground and shelter for small fishes and others marine organisms. Seagrass decline caused by the macroalgae blooms is becoming a common phenomenon throughout temperate and tropical regions. Abiotic factors such as light availability, sedimentation rates, nutrient load and physical stresses are responsible for the regulation, maintenance and growth of seagrass meadows as also observed. However, seagrass meadows are rapidly declining all over the world, due to increasing anthropogenic activities in coastal areas. Human pressures on coastal areas are also increasing, and factors like booming tourism, growing industries, oil drillings and spills, trace metal pollution and eutrophication threaten coastal ecosystems. In India continent is represented 16 species of seagrass with an approximate cover of 500 sq km at isolated locations along the coast, lagoons, backwaters and estuaries. Shrinking of seagrass meadows from different regions of India constitutes the nutrients contents are recorded comparatively higher concentration in Gulf of Mannar and the water and sediments were contaminated with trace and heavy metals in the area which is impact to seagrass ecosystem. Poor seagrass health was observed in studies in Palk Bay due bad water quality and fishing boat momentum in these areas. Due to high nutrient load, the inter specific competitions with micro- and macrophytes are predominant stressors for seagrass growth. An important stressor that has not been well studied in the Caribbean is eutrophication. In some regions of Southeast Florida nitrogen over- enrichment led to nuisance blooms of ephemeral seaweeds, which can have severe impacts on seagrass beds and coral reefs. After reviewing the research articles, it concluded that occurrence of nutrient load is due to anthropogenic and industrial activities. So, these practices to be reduced and proper treatment must be exercised before releasing of contaminated waters.

23 Marine Ecosystems and Biogeochemistry of the Ocean

Characterization of extracellular enzyme activities of bacteria from the water and sediment sand along the west coast of India during monsoon season. QUICK ORAL Ashutosh S. Parab1,2, Mayukhmita Ghose1, Cathrine S. Manohar1 OSICON2021/144 1Biological Oceanography Division, CSIR- National Institute of Oceanography, Dona Paula, Goa ; 2School of Earth, Ocean and Atmospheric Sciences, Goa University, Goa

The west coast of India, along the Arabian Sea is one of the highly productive region of the world ocean. Monsoonal changes in the water column chemistry results in increased biological production, consequently it leads to the generation of a huge amount of organic matter in this region. The complex organic matter generated in sediment and water column during the productive season attracts bacterial communities possessing the ability to utilize this organic matter through their extracellular enzyme activities, which plays important ecological role in the recycling of organic matter in sediment and water column. In this study the bacterial productivity, abundance and culturable bacterial diversity during the productive monsoon season was estimated. For this, water and sediment samples were collected in Septem- ber 2019 from nine stations along the west coast of India at 30 m, 300 m and 600 m depth contours off Goa, Mangalore, and Trivandrum on board RV Sindhu Sankalp (SSK-131). The primary and secondary productivity was estimated in-situ using radio-labelled substrates. Bacterial abundance, growth efficiency and viable counts were also determined following standard methodologies in the water and sediments samples. A total number of 136 and 86 different bacterial morphotypes were isolated from water and sediment samples respectively and characterized for their extracellular enzyme activities using quantitative plate assay for 4 monosaccharides, 5 polysaccharides, lipid, and protein substrate. The present study found that bacterial abundance during the monsoon season was in the order of 107 cells mL−1 in both the sediment and water column. However, a significant difference was observed in the total viable counts enumerated, the counts were 103 to 104 CFU mL−1 in water samples and in sediment samples, it was 106 CFU mL−1 . labelled substrates. Extracellular enzyme activity studies showed that around 50% of bacterial morphotypes isolated from water and sediment samples showed positive results for more than 7 extracellular enzymes. Alginate lyase, hexokinase, agarolytic enzymes were the most expressed enzymes by bacterial morphotypes isolated from water and sediment samples. This study provides us the functional diversity of bacteria from the sediment and water column along the west coast of India in the monsoon season.

24 Marine Ecosystems and Biogeochemistry of the Ocean

Morphological and taxonomic diversity of micro-phytoplankton from the south-eastern Arabian Sea during 2020 winter monsoon: elucidation from surface and sub-surface chlorophyll maximum layers QUICK ORAL Paul P., Patil J. S. OSICON2021/162 CSIR-National Institute of Oceanography, Dona Paula, Goa

Understanding and explaining the structure and dynamics of communities in relation to environment is a main focus in phytoplankton ecology. In this study, the micro-phytoplankton (>20 µm) communities are described based on taxonomy and morphometry from the south-eastern Arabian Sea during winter monsoon (January to February 2020). The water samples from the surface and sub-surface chlorophyll maximum layers (SCMLs) were collected during RV Sindhu Sadhana cruise (SSD069) along the two east-west open ocean transects (water column depth 2000- 4000m): T1 (10 stations in oligotrophic condition) and T2 (4 stations in Oxygen Minimal Zone) to decipher the differences in micro- phytoplankton distributions. The SCMLs was deeper (56-95m) in T1 than T2 (20-35m) transects. Here micro- phytoplankton shapes (morphotypes) and taxa are used as traits to understand micro- phytoplankton distribution patterns. The results revealed that the phytoplankton biomass, abundance, number of species and composition (both morphotypes and taxa) were relatively higher in T1 than T2. Overall, diatoms dominated the micro-phytoplankton community (79-92%) and the maximum contribution was recorded along transect T1. A total of 59 (30 diatoms and 29 dinoflagellates) and 75 (46 diatoms and 29 dinoflagellates) micro-phytoplankton species corresponding to 12 and 14 morphotypes were recorded in surface and SCMLs, respectively. T1 showed equal number of shapes (11 each) in both surface and SCMLs, whereas in T2 shape variability was slightly more in the SCMLs (11 shapes) than the surface waters (8 shapes). Though micro-phytoplankton taxonomic diversity exhibited distinct variations among the studied locations the shape diversity showed (i) similar dominance patterns (Cylinder shape) in surface waters and (ii) dissimilar dominance patterns between the deeper (Cylinder in T1) and shallower (Prism on parallelogram shaped pennate diatoms in (T2) SCMLs. This presentation provides the basis to understand the community dynamics in the high chlorophyll zone of the open ocean.

25 Marine Ecosystems and Biogeochemistry of the Ocean

Kinetic speciation of Cu,Ni,Co in Deep Sea sediment from the Central Indian Ocean Basin QUICK ORAL Lamjahao Sitlhou1,2, Sucharita Chakraborty1,2, Prasad Padalkar1,2, Kartheek OSICON2021/163 Chennuri2, Ishita Ishita3, N. H. Khadge2, Parthasarathi Chakraborty1,2 1Centre for Oceans, Rivers, Atmosphere and Land Sciences, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal; 2Geological Oceanography Division, CSIR-National Institute of Oceanography,Goa; 3Department of Chemical Engineering, BITS Pilani, K. K. Birla Goa Campus, Zuarinagar, Goa

Deep sea floors are the reservoir for various marine mineral deposits rich in strategic metals. Seabed areas were allotted to the pioneer investors with exclusive rights over the mineral deposits in different parts of the world oceans by the International Seabed Authority (ISA, 1998) established under the UN Law of the Sea. India has also been allocated vast areas in the Central Indian Ocean Basin (CIOB), covering 75000 km2 to carry out scientific exploration and research activities. Needless to say, a new challenge of deep sea mining is underway. Study on the possible impact of deep sea mining in future requires systematic scientific investigation. CIOB is a region with vast marine mineral deposits with a congregation of metals in the form of nodules known as polymetallic nodules (also known as ferromanganese nodules). This study aimed to assess the probable impact of deep sea mining activities (in near future) from the CIOB on Metal (Cu, Ni, Co) speciation and its distribution. Kinetic speciation of sedimentary metals from CIOB was carried out to assess the nature of metals-sediment complexes with respect to depths of the two individual sediment coressampled from the Central Indian Ocean Basin (CIOB) region. Kinetic speciation is a method capable of determining kinetically distinguishable (labile and Inert) metal complexes (in water column/sediment) and their corresponding dissociation rate constants in the marine ecosystem. The total metal concentration of Cu and Co was high at the surface of the sediment cores whereas the total Ni concentration was low at the surface of the sediment cores. The total concentration of Cu and Co gradually decreases, whereas Ni shows gradual increase with increasing depth of the sediment cores. Further, metal-speciation study at regular depth intervals of the two sediment cores suggests that the concentration of labile Cu, Ni and Co in the sediment decreases with the increasing depth of the sediment cores (with faster dissociation rate constants). The observed results suggest that the stability of metals-sediment complexes for Cu, Ni and Co with respect to the depth of the sediment cores gradually increased in the study area. This study suggests that disturbances of deep-sea sediments during PMN mining may not increase labile metals-sediment complexes at water sediment interfaces at the surrounding marine ecosystem. Further study is recommended to provide useful information on fate and bioavailability of sedimentary metal complexes in the CIOB.

26 Marine Ecosystems and Biogeochemistry of the Ocean

Frontal variability of Phytoplankton in the Indian sector of Southern Ocean during Austral Summer 2018 QUICK ORAL Sreerag A.1,2, R. K. Mishra1, Ravidas K. Naik1,Melena A. Soares1, Resha Mahale1 OSICON2021/168 1ESSO-National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Government of India, Vasco-da-Gama, Goa; 2Bharathidasan University, Palkalaiperur, Tiruchirappalli, Tamil Nadu

Phytoplankton community plays a vital role in governing the global climate by influencing various biogeochemical processes in the Southern Ocean (SO) and said to be the foundation of ocean food web. The SO facilitate by regulating about 75% of this global oceanic uptake of excess heat and nearly 35% of the global sink of excess carbon from the atmosphere. The diversity of phytoplankton species in open waters has fascinated ecologists for long time, but the pattern of this diversity and its underlying factors have been unclear in the global ocean including Indian Ocean sector of SO. Therefore, it is crucial to estimate the spatial and temporal variabilities of phytoplankton production for the better understanding of biogeochemical cycle and climatic change. Samples were collected during Indian Scientific Expedition to the Southern Ocean-2018, indicate variations in tolal biomass (Chl-a) along the ocanic fronts. Phytoplankton community and Chl-a was studied using microscopic analysis and flurometric measurements. Phytoplankton biomass varied from 0.1-0.4 mg/m3 at surface waters, 0.1-0.3 mg/m3 in Deep Chlorophyll Maxima (DCM) and 0.01-0.1 mg/m3 at 120m depth. Microscopic observations shows that the total abundance of phytoplankton were higher in Polar front (PF) compared to Subtropical front (STF) in surface waters. The diatoms contribution were higher than dinoflagellates to the total biomass in the PF and diatoms showed increasing trend from STF to PF through Subantarctic front (SAF). Whereas, dinoflagellates showed a decreasing trend from STF to PF in the surface waters. However, the governing factors for phytoplankton community variations along the fronts needs to be monitored through high resolution observation to better understanding the role of phytoplankton in Indian sector of SO.

27 Marine Ecosystems and Biogeochemistry of the Ocean

Seasonal variation of POC in Bay of Bengal using Satellite Data QUICK ORAL Soubhik Bhattacharya, Sudeep Das, Sourav Sil, Syed Hillal Farooq OSICON2021/175 School of Earth, Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar, Odisha

Many large rivers discharge significant quantities of freshwater into the Bay of Ben- gal (BoB). This impacts the salinity, temperature, suspended particulate matter, availability of nutrients, organic matter, etc., in the BoB water. Further, the western BoB experiences the northward and southward currents during the spring and autumn seasons, which also affects the vital parameters in the Bay. The present study investigates the seasonal variation of the Particulate Organic Carbon (POC) in the BoB and identifies the role of the ocean currents and rivers in its distribution. The seasonal data from the MODIS-Aqua satellite (source : https : //oceancolor.gsfc.nasa.gov/l3/) shows that the POC has higher accumulation on the nearshore regions of the BoB with a high seasonal variation. The post-monsoon season shows a higher POC concentration due to increased river discharge and surface run-off, including the water from nearby agricultural land with high organic carbon. The Autumn season has the highest POC accumulation which subsequently decreases during winter and spring. During the summer, POC starts to accumulate again mainly due to eddy formation by low pressure and high seawater temperature. In the Autumn season, POC concentrates more along the Indian coastal margins where Ganga, Mahanadi meets the ocean and moves towards the Bangladesh, Myan- mar coasts. In the Autumn of 2013, POC accumulation was higher in the offshore regions in the Bay of Bengal, at the confluence of Godavari and Krishna. In winter 2009, POC distribution was observed from the Mahanadi river estuary towards offshore regions. Localized concentration seems to be formed by eddy which acts as a biological pump system. In Autumn 2004, POC showed the highest assemblage in the Ganga and Mahanadi estuary. At places, the POC concentrations as high as 1200 mg.m-3 and 900 mg.m-3 have been found in the Ganga and Mahanadi estuary, respectively. However, the Godavari estuary in the summer season shows more POC clustering due to increased river discharge and the POC concentration remains lower than 350 mg.m-3. The POC indicate that the river run-offs and cyclonic eddies played an important role in controlling the quantity of POC in the Bay of Bengal.

28 Marine Ecosystems and Biogeochemistry of the Ocean

Emergence of omics as a tool to study life in the Oceans ORAL OSICON2021/179 Samir R. Damare Biological Oceanography Division, CSIR-National Institute of Oceanography, Goa, India.

Life in Oceans have always intrigued humanity, and the quest for exploring diversity is increasing. In the last two and half decades, new technologies have emerged in the field of sequencing and mass spectrometry which are being targeted to understand life in Oceans. Here we discuss four major areas of omic research that are gaining popularity to understand life in the Oceans. The identification of marine organisms has become more consistent with the help of nuclear and mitochondrial genome studies. The metagenome studies are still evolving and not yet being used widely. The advances in genomic tools and developments in oceanography have resulted in a better understanding of the relationship between marine life and its impact on the ecosystem. Metatranscriptomic analysis helps understand how the microbiome reacts to the environment by studying the functional analysis of the genes expressed in the microbiome. Metatranscriptome can also help us estimate the taxonomic composition of the microbial population. With the advances in metatranscriptomics, it has become possible to evaluate the impact of changing climatic conditions on marine organisms. Proteomics is the third technique to analyse the functional genome of marine organisms. For the biological processes to be understood, genetic studies should be complemented with proteomics studies. The fourth of the omic technologies is metabolomics. This is the study of low molecular weight metabolites found in the cells. Metabolomics is different from other omic approaches as it responds to stressful and natural conditions. Unlike the genes, transcripts and proteins, the metabolites are compounds with diverse physicochemical properties. Hence, there is no single universal technique available that is capable of measuring all types of metabolites.

29 Marine Ecosystems and Biogeochemistry of the Ocean

Salinity changes may influence dinoflagellate cyst morphometry: data from monsoon influenced tropical coastal ecosystems ORAL OSICON2021/190 R. V. Rodrigues, J. S. Patil CSIR - National Institute of Oceanography, Dona Paula, Goa

Generally, dinoflagellate cyst morphology are species-specific, and its variability due to environmental factors (temperature and salinity) make them potential proxies. Morphological variability in certain dinocysts is well documented elsewhere but lacking from monsoon-influenced coastal ecosystems. This study on distribution and morphometry variability on two dinoflagellate cysts, Pyrophacus steinii (au- totrophic) and Protoperidinum pentagonum (heterotrophic), from estuarine (Cochin port and Zuari estuary) and marine (New Mangalore port) ecosystems along the west coast of India revealed that both are dominant and euryhaline species. Fur- ther, variability in cyst morphometry was also observed between the ecosystems and was following salinity values as the influence of other environmental parameters (i.e., the prevalence of narrow temperature range and nutrient-rich conditions) may not be dominant. Cyst length, breadth, and processes length (only in P. steinii) of both the dinoflagellates were relatively larger and smaller at higher (> 25 psu) and lower salinity (< 25 psu) ranges, respectively. The occurrence of both the cyst at a much wider salinity range, presence of significantly larger sized P. steinii cysts (up to120 µm in Zuari estuary) compared to available reports (including other ports), and salinity-wise variability in P. pentagonum cysts size are the new information contributing to their biogeographic distribution and eco-biology of dinoflagellate cysts per se. This study confirms that, in addition to cysts with processes, some cysts without processes exhibit size variability in different environmental settings. Such cysts (if dominant) can form alternative environmental indicators in regions where known indicator species are less predominant.

30 Marine Ecosystems and Biogeochemistry of the Ocean

Marker pigment based phytoplankton community structure in relation to wind forcing in the central Arabian Sea: SW monsoon (2017-2018) QUICK ORAL Mintu Chowdhury, Haimanti Biswas OSICON2021/193 CSIR National Institute of Oceanography, Biological Oceanography Division, Goa

The central Arabian Sea experiences an Open ocean upwelling during the southwest monsoon (SWM) due to the development of positive wind stressed curl induced by a low-level atmospheric jet (Findlater Jet) in its northern part. And consequently, in the south of the jet axis downwelling occurs forced by the negative wind stress curl. Our study provides new insights into the pigment-derived phytoplankton community structure and its dependence on various environmental conditions in the central Arabian Sea during two consecutive summer monsoon cruises (2017 and 2018) along the central Arabian Sea (640E) from 210N to 110N. A clear north-south variability in major phytoplankton dominance (micro, nano, picophytoplankton) was evident and was closely coupled with physicochemical variabilities. A distinct demarcation from microphytoplankton to picophytoplankton from north to south was observed. Microphytoplankton dominated the high nutrient upwelled water in the north of Findlater Jet, whereas picophytoplankton was associated with warm, oligotrophic water in the south. Fucoxanthin, the marker pigment of diatom was increased during 2018 suggesting more diatom availability than in 2017. Nanophy- toplankton mostly contributed by coccolithophores were associated with the high wind and turbulent water in the axis of the Findlater Jet. More intense oligotrophy in the southern stations led to the dominance of picoplanktonic cyanobacteria in 2017 than in 2018. Zeaxanthin (marker pigment of cyanobacteria) concentration, decreased and was conﬁned more towards the south during 2018. DV-Chl a, representative of picoplanktonic cyanobacteria Prochlorococcus was one of the major contributors to the TChl a of the study region during both years. We show that interannual variability in phytoplankton community was directly controlled by the wind forcing and any future change in this physical forcing may signiﬁcantly modify the phytoplankton distribution in this region.

31 Marine Ecosystems and Biogeochemistry of the Ocean

Simulated ocean acidiﬁcation and Cu enrichment promote pennate diatom dominance in the central Arabian Sea QUICK ORAL Diksha Sharma, Haimanti Biswas OSICON2021/194 CSIR National Institute of Oceanography, Biological Oceanography Division, Dona Paula, Goa 403004, India

Ocean acidiﬁcation may potentially restructure marine phytoplankton communities and has been reported from various eco-geographic provinces. At the same time, trace metal pollution is intensifying globally and also impacting the marine ecosystem. Multiple stressor studies are becoming increasingly important from the perspective of climate change despite their complexity. Studies on trace metal toxicity under ocean acidiﬁcation are still poorly addressed and need immediate attention. The Arabian Sea is one of the highest productive oceanic provinces and such multiple stressor studies are very rare from this highly dynamic region. Certain areas of the Arabian Sea receive a large volume of Cu-enriched atmospheric dust to the surface waters which can be toxic for phytoplankton. Here, we present the results of a microcosm experiment conducted onboard RV Sindhu Sadhana on a natural phytoplankton community from the central Arabian Sea during the north-east monsoon (December 2019). The experimental phytoplankton community responded positively to CO2 enrichment and exhibited higher cell density. Under the ambient CO2 level

(A − CO2), Cu- addition inhibited cell division, whereas, Chla content did not show such negative impacts. Interestingly, in the H − CO2 treatment, Cu-enrichment did not cause any toxic impact, although there was a distinct community shift. DSi concentration was limiting (< 2µM) and promoted the prevalence of pennate diatoms like Nitzschia sp. and Pseudo-nitzschia sp. and prymnesiophytic algae, particularly in the Cu-treated samples. The occurrences of Nitzschia and Pseudo-nitzschia in association with Cu enrichment have been reported repeatedly from many areas including our previous studies. We show here for the first time that increasing CO2 levels exhibited a growth-stimulating impact and may reduce the toxic impacts of Cu- enrichment in the central Arabian Sea phytoplankton communities during the winter monsoon season. The proliferation of toxin producing pennate diatoms under DSi limited condition is likely to occur in the future ocean and Cu enrichment may further promote their growth. This study collectively suggests that the phytoplankton community of offshore Arabian Sea waters may experience a distinct shift in response to the projected ocean acidification, oligotrophy, and Cu pollution. This community restructuring may exert some significant changes in the trophic level and organic carbon cycling.

32 Marine Ecosystems and Biogeochemistry of the Ocean

13 15 The impacts of physical forcing on POM, δ CPOC and δ NPN variability in the central Arabian Sea during SW monsoon (2017-2018) ORAL OSICON2021/195 Saumya Silori, Haimanti Biswas CSIR National Institute of Oceanography, Biological Oceanography Division, Dona Paula, Goa 403004, India

The central Arabian Sea has always attracted oceanographers for studying the impacts of ocean atmospheric forcing on biological processes particularly due to the occurrences of Open ocean upwelling during the southwest monsoon (SWM), the most productive time of the year. However, extreme weather conditions and other logistical issues are usually a barrier to explore this dynamic basin. A low-level atmospheric jet forms in the central Arabian Sea (Findlater Jet) during the SWM and creates extremely diverse hydrography and biogeochemistry. There are very few studies that described the particulate organic matter (POM) dynamics along with stable carbon and nitrogen isotopes in this area. After two decades of JGOFS (1992-1997), we present here the first report by interlinking hydrography as well as physicochemical features with the POM dynamics during two consecutive SWM cruises (110-210N; 640E) (August 2017 and 2018). A strong interannual variability was observed in all parameters and a significantly higher wind speed and jet-induced wind stress curl coupled with low sea surface temperature (SST) were noticed in 2018 than in 2017. The nutrient concentrations in the mixed layers were directly linked to the wind speed. The maximum POM contents were noticed in the northern part 13 of the jet axis. δ CPOC values (-26.3±1.4 in 2017; 25.5±1.4 in 2018) exhib- 15 ited typical marine phytoplankton signature. δ NPN values (7.68±2.6 in 2017; 9.24±3 in 2018) indicated regenerated nitrogen coming from the oxygen minimum 15 zone (OMZ), particularly in the north of the jet axis. δ NPN values also suggested the presence of advected nitrogen from the Somali upwelling to the axis of the jet and south of it. The interannual differences in SW monsoon onset and wind speed seem to directly control the nutrient supply, affecting plankton community structure and POM variability. Thus, any future change in the physical forcing may directly influence the POC pool and consequent export flux to the mesopelagic.

33 Marine Ecosystems and Biogeochemistry of the Ocean

Potential of marine bacteria for biodegradation of polycyclic aromatic hydrocarbon QUICK ORAL Vasudha C. Bhatawadekar1,2, Samir R. Damare1 OSICON2021/196 1Biological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, Goa; 2 Department of Microbiology, Goa University, Goa, India

World energy demand is met primarily by extracting fossil fuels from oil, coal, and gas. Tons of hydrocarbons enter the environment due to calamities like the oil spill, tank leakages, and several anthropogenic activities. Polycyclic aromatic hydrocarbon is also released into the environment, leading to long-term consequences that severely affect the environment, ecosystem, human and animal health. Biore- mediation can be considered as a boon for their degradation. Bacteria play an important role in utilizing aromatic hydrocarbon as a sole carbon source for growth and energy and thereby helping in mitigating its pollution. Marine bacteria have an advantage over terrestrial bacteria as they can grow in extreme environmental conditions. This study focuses on the potency of marine bacteria to degrade polycyclic aromatic hydrocarbon. Six bacterial strains isolated and screened previously were studied for their degradation ability of phenanthrene, fluoranthene and pyrene. Amongst them, two bacterial isolates exhibited over 80% degradation of phenanthrene. Sequence analysis showed that NIOSV7 (Pseudomonas pachastrel- lae) could degrade 83.33% phenanthrene, 40.22% fluoranthene and 45.28% pyrene. Another bacterial strain NIOSV8 was identified as Pseudomonas oleovorans with 85.09% phenanthrene, 70.61% fluoranthene and 67.18% of pyrene degradation in 120 h at 100ppm initial concentration of each hydrocarbon. Though many Pseu- domonas sp. documented for PAH degradation, it is the first report showing high PAH-degradation efficiency of Pseudomonas oleovorans.

34 Marine Ecosystems and Biogeochemistry of the Ocean

Eﬀect of nutrient enrichment under pressure on the microbial diversity- A metagenomic approach QUICK ORAL Shruti Shah1,2 Samir Damare1 OSICON2021/207 1Biological Oceanography Division, CSIR- National Institute of Oceanography, Dona Paula, Goa; 2School of Earth, Ocean and Atmospheric Sciences, Goa University, Goa, India

High hydrostatic pressure, low temperature, absence of solar radiation and oligotrophic conditions are the main characteristics of the deep sea environment. Mi- croorganisms thriving under such extreme conditions are known to play major role in nutrient and biogeochemical cycles. However, majority of these organisms are uncultivable and hence the knowledge about their taxonomic and functional role remains unknown. Here, we report the effect of nutrient enrichment on the prokaryotic community of the sediments using metagenomic approach obtained from two locations #PRZ (Preserved Reference Zone) and #BC20 (Control site, outside potential mining area) in Central Indian Ocean Basin from an average depth of 5100 m under simulated conditions. The sediment core obtained using multicorer was sub-sectioned and the sub-sections were enriched with 1:10 Zobell Marine broth and incubated at 500 MPa and 4oC, while non-enriched and non-pressurized samples were used as control. A total of 4935264 and 6405881 reads corresponding to 23983 and 16866 OTUs were obtained from the control and enriched samples respectively. These OTUs classified into a total of 46 phyla and 128 classes. A comparison of the control and enriched samples from #BC20 identified Firmicutes, Chloroflexi and Bacteroidetes as major groups that got enriched. Among the samples from #PRZ, Proteobacteria, Chloroflexi and Firmicutes were the major microbial groups. There was no effect of nutrient enrichment on the abundance of the archaeal groups among sediment samples from both the locations. The overall diversity of the prokaryotic groups in control and enriched samples remained unaffected. Proteobacteria was the most dominant phylum in nutrient-enriched pressurized as well as non-pressurized and non-enriched sediment samples.

35 Marine Ecosystems and Biogeochemistry of the Ocean

Phytoplankton community structure in relation to the environmental conditions from the tropical Kandla port ecosystem ORAL OSICON2021/215 Aseem R. Rath1,2, Smita Mitbavkar1, A. C. Anil1 1Council of Scientiﬁc and Industrial Research, National Institute of Oceanography, Goa; 2School of Earth, Ocean and Atmospheric Sciences, Goa University, Goa

: Phytoplankton response to environmental conditions is known to be rapid due to their higher growth rates and hence serve a vital role as ecological indicators. Seasonal sampling was conducted from October-2014 to February-2016 at Kandla port, Gujarat, along the west coast of India. A total of 26 stations located adjacent to the industrial (station 1 to 8), port (station 9 to 20) and mangrove (station 21 to 26) regions were sampled. The Kandla port ecosystem exhibited higher water temperatures (30oC) during post-monsoon and monsoon and lower (21oC) during pre- monsoon. The salinity varied from polyhaline (18-30 psu; monsoon) to euhaline (30 to 45; non-monsoon). The strong currents, high tidal activity, shallow depth areas (mangrove areas), and the creek backwater systems make this ecosystem well-mixed and turbid. The annual average trophic index (TRIX) scores indicated very good water quality and low eutrophication due to the well-mixed water column except in the industrial area during pre-monsoon. Overall, 47 phytoplankton species represented by diatoms, dinoflagellates, and silicoflagellates were observed. The diatoms dominated the community in terms of taxa and abundance. The dinoflagellates were represented by phototrophic, heterotrophic, and mixotrophic types. The phytoplankton abundance was lowest during the monsoon (Thalassiosira sp. dominant) due to the highly turbid water column. It was highest during the post-monsoon in the industrial area (pennate diatoms; Thalassiothrix longissima, Fragillariopsis sp., Pseudo-nitzschia sp. and phototrophic dinoflagellate Gymnodinium sp.) when less turbid waters and high ammonium concentrations (> 15 µM) prevailed. The hypersaline pre-monsoon environment with lower annual temperature, comparatively lower turbid waters, and high nutrients favoured higher diatom diversity. These conditions also promoted potentially harmful Gymnodinium sp. and bloom-forming Tripos furca and Pyrophacus sp. in the mangrove area. Overall, ten non-toxic but bloom-forming species were observed. Although the lower abundance of these species does not make the region vulnerable to harmful algal blooms, the nutrient enrichment episodes and favorable environmental conditions could create alarming situations. The study provides insights into the phytoplankton community’s response to environmental conditions that can have repercussions on the ecosystem’s functioning.

36 Marine Ecosystems and Biogeochemistry of the Ocean

Impact of Covid-19 lockdown on the base of marine food web in the North Indian Ocean QUICK ORAL Swastika Bhaumik OSICON2021/219 Indian Institute of Technology Kharagpur

The novel coronavirus pandemic (COVID-19) has brought the world to a standstill in the early part of 2020. Several countries have imposed lockdown in order to avoid spreading the disease. As a result, all human and industrial activities were stopped. Fewer pollutants were supplied in to the environment by the atmosphere and from discharge by the rivers during the lockdown period. The present study focuses on the changes in the magnitude of satellite retrieved chlorophyll-a(chl-a) data from MODIS-AQUA sensor, oﬀ major cities(Kolkata, Vizag, Chennai, Kochi, Mumbai, Gujarat) along Arabian Sea and Bay of Bengal and also regions in Central Arabian Sea and Central Bay of Bengal. During the total lockdown period, the magnitude of chlorophyll reduced in the waters of both the Arabian Sea and the Bay of Bengal as compared to the last decade, signifying the eﬀect of decline in the supply of anthropogenic nutrients by the atmosphere and through river discharge.

37 Marine Ecosystems and Biogeochemistry of the Ocean

Development of a bioenergetics model for Indian oil sardine (Sardinella longiceps) and simulation of its seasonal growth along the Indian west coast ORAL OSICON2021/224 Faseela Hamza1, Anju M1,2, Vinu Valsala1, Smitha B.R.3 1Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune, India; 2Department of Meteorology and Oceanography, College of Science and Technology, Andhra University, Vishakhapattanam, India ; 3Center for Marine Living Resource and Ecology, Ministry of Earth Sciences, Kochi, India

Wide stock fluctuation was observed with the Indian oil sardine (Sardinella longiceps) fishery along the Indian west coast. Ecological parameters, mainly temperature and prey density, had a profound influence on the growth of S. longiceps and hence the production. In this study, a fish bioenergetics model, coupled with a lower ecosystem model, was developed to reproduce the seasonality in the growth of S. longiceps. For this, we have used an Indian Ocean adaptation of an intermediate complex ecosystem model called North Pacific Ecological Modeling for Understand- ing Regional Oceanography (NEMURO) for marine productivity simulations. The model has 13-component ecosystem variables such as two types of phytoplankton (small and large including flagellates and diatoms), three types of zoo- planktons (small, large, and predatory, which includes ciliates, copepods, and euphausiids), particulate and dissolved organic matter, cycling of nitrate, ammonia, silicate, and calcium. The prey densities derived from the NEMURO were input to the sardine bioenergetics model. The coupled model reproduced the appropriate growth rate and wet-weight of S. longiceps in its seasonal cycle in four major fishery regions such as Kochi, Goa, Ratnagiri, and Mumbai as verifiable from the available observation. In Kochi, the mean wet weight was 72.0±12.8g (June to September), 65.4 ± 5.3g (October to November), 82.4 ± 2.7g (December to February), and 66.7 ± 3.8g (March to May). Goa and Ratnagiri have moderate weights with mean wet weight as 73.6 ±10.6 g (June to September), 87.4 ± 3.2 g (October to November), 95.5 ± 4.3 g (December to February), and 76.2 ± 6.8 g (March to May). In the Mumbai region, maximum weight is simulated with mean wet weight as 97.4 ± 13.3 g (June to September), 102.1±1.6 g (October to November), 104.8 ± 1.3 g (December to February), and 101.6 ±1.2 g (March to May). Sensitivity analysis revealed the importance of temperature and consumption in the growth of sardine. Detailed model validation with available observations is presented.

38 Marine Ecosystems and Biogeochemistry of the Ocean

Iron biogeochemistry in the Southern Ocean QUICK ORAL Diptangshu Sarkar, Parthasarathi Chakraborty OSICON2021/225 Department of Centre of Oceans, Rivers, Atmosphere and Land Sciences (CORAL), Indian Institute of Technology Kharagpur, Kharagpur, West Bengal

Oceanic regions featured by perennially high macronutrient levels yet low and constant levels of phytoplankton growth have been a inconsistency long documented by oceanographers. These regions are commonly called the high nutrient and low chlorophyll a (HNLC) regions and Southern ocean is one of such oceans where even with nutrient enriched cold deep waters the plankton growth is limited. Since 1930 oceanographers have cited iron supply as one of the reasons for the occurrence of such regions. The development of the Iron Hypothesis, which correlated variation in iron supply to the ocean with change of rates of primary production and the succeeding magnitude of carbon sequestration in HNLC waters through the geological history. Afterwards, the development of the subsequent Iron hypothesis has provided a comprehensive outline that links iron supply, foodweb structure, and macronutrient supply to explain the persistence of low and constant phytoplankton stocks in these HNLC regions. Even though lab cultures and shipboard iron en- richments presented many inferences it was thought that performing large-scale in situ fertilisations would capitulate further valuable insights into the functioning of these regions. Hence this lead to the insitu Iron fertilisation experiment in Southern ocean called Southern Ocean Iron RElease Experiment (SOIREE) provides unequiv- ocal evidence of iron limitation of phytoplankton processes in summer in the waters in the polar Australasian-Pacific sector of the Southern Ocean. A second in situ iron release experiment, EisenEx, was performed in austral spring 2001 in the Atlantic sector of the Southern Ocean, and reported that a massive diatom bloom (chlorophyll >2 mg m-3) resulted. This was followed by the Indo-German OIF experiment LOHAFEX was carried out over 40 days in late summer 2009 within the cold core of a mesoscale eddy in the productive south-west Atlantic sector of the Southern Ocean. Such information will be crucial to better model the ocean biogeochemistry of iron and how it relates to the carbon cycle. These models will be particularly useful tools to help provide a better understanding the biogeochemistry of these waters. In this presentation, I provide an insight of the main findings of the different experiments conducted to understand the Iron biogeochemistry in the Southern ocean and hint the focus of future Southern Ocean studies.

39 Marine Ecosystems and Biogeochemistry of the Ocean

The ﬁrst report of seasonal distribution of phytoplankton functional type (PFT) & phytoplankton size classes (PSC) in Chilika, the largest coastal lagoon in India QUICK ORAL Sambit Singh2, Tamoghna Acharyya1, Anu Gopinath2 OSICON2021/230 1School of Sustainability, XIM University, Bhubaneswar, Xavier City Campus, Harirajpur, Puri, Odisha ; 2 Department of Aquatic Environment Management Kerala University of Fisheries and Ocean Studies (KUFOS), Kochi, Kerala

Phytoplankton Functional Types (PFTs) are conceptual groupings of phytoplankton species, having common ecological functionality- such as nitrogen fixers (e.g., Trichodesmium), calcifiers (coccolithophores), DMS (Dimethyl Sulphide) producers (e.g., Phaeocystis & Dinoflagellates) and silicifiers (e.g., diatoms). Phytoplankton Size Classes (PSC) is based on classifying phytoplankton under size continuum of Pico ¡Nano¡ Micro-phytoplankton. PFTs are gaining greater attention for their potential application as a relevant proxy of ecosystem functioning (export of organic carbon vs local recycling) and climate change whereas PSCs for monitoring of water bodies. However, virtually no studies have focused on PFTs and PSCs on coastal wetlands. Estimating PFT and PSC by microscopy is limited by taxonomic skill of an individual who need to toil segregating phytoplankton under various size classes which is inefficient as well as inaccurate. These can be rapidly analyzed employing HPLC pigment analysis protocol, which is more accurate, cost- effective, seamless & capable of giving high frequency monitoring of water quality health. In this abstract we present first ever report on spatio-temporal distribution of PFT and PSC in the largest coastal lagoon in India, Chilika by pigment indexing approach. The HPLC pigment data was also supported by various water quality data. These data enabled us to further investigate the controlling mechanisms for distribution of PFT and PSC across the four ecological zones/sectors of the lagoon. Array of pigments such as neoxanthin, prasinoxanthin, violaxanthin, alloxanthin, lutein, zeaxanthin, beta carotene and fucoxanthin have been identified from the HPLC chromatogram. Our preliminary data suggest that in brackish Southern and Central sector both marine and freshwater phytoplankton of various size ranges are capable of thriving. The silicifiers are prevalent throughout the lake especially at the Central and Southern sectors. Nano and pico-phytoplankton dominated by green algae and cyanobacteria were prevalent in the northern sector which remains mostly fresh throughout the year. DMS producers were confined towards the outer channel due to proximity to the Bay of Bengal. Calcifiers, represented by the coccolithophores were also recorded from the outer channel. Abundance of micro-phytoplankton phytoplankton (majorly diatoms) in the outer channel were more successful since they could extract soluble silica from water column.

40 Marine Ecosystems and Biogeochemistry of the Ocean

Abundance and Distribution of Microplastics in the Water Column of Southern Ocean ORAL OSICON2021/232 E.V.Ramasamy, Ajay Kumar Harit, Naveen Babu School of Environmental Sciences, Mahatma Gandhi University, Kottayam, Kerala, India-686560

Microplastics are tiny (<5mm) plastic particles found almost in all kinds of aquatic (fresh and ocean water) and terrestrial ecosystem. They are pervasive in nature thus ubiquitous in distribution, their presence has also been reported in pristine locations such as Arctic ecosystem and Himalayan Mountains. Comparatively the reports on Microplastics abundance and distribution in Southern Ocean towards Antarctic are limited. In this context, the present study reports the occurrence of Microplastics in Southern Ocean. Water samples were collected from ten locations at different depths of the ocean water column as a part Indian Scientific Expedition to Southern Ocean (ISESO 2019-2020). Surface water sampling was also done by grab sampling technique, while depth water samples were collected using depth sampler. Standard protocol as prescribed by National Oceanic and Atmospheric Administration (NOAA) for extraction of MPs was followed. The steps involved are as follows: Water samples after initial screening were subjected to wet peroxide oxidation (WPO) followed by floatation and vacuum filtration of the supernatant over Glass-Fibre filter paper (GF-A) . The oven dried (40oC) filter papers were observed under stereomicroscope (Zeiss Stemi 508). Micro Raman spectroscopy (WITec Alpha 300RA, Germany) was used to identify the polymer profile of the microplastics. Microplastics were recorded from the samples of all locations; most of them were of fibre shape followed by fragments, and film (very few). Polyethylene, Polypropylene, High density polyethylene, and Polyamide were the predominant polymers identified. This findings of this study, being a pioneering study reporting the occurrence of Microplastics in the Southern Ocean water for the first time as a part of the India Southern Ocean Expedition, provide impetus for further research on the abundance, distribution and impact of this emerging pollutant in Southern Ocean.

41 Marine Ecosystems and Biogeochemistry of the Ocean

Environmental interaction of water quality, phytoplankton and zooplankton in pelagic food web of Ghogha coastal waters in Gujarat ORAL OSICON2021/245 S. Sundaramoorthy, G. Idayachandiran , J. Jaganmohan Indomer Coastal Hydraulics (P) Ltd. Chennai

The study pertains to seawater nutrients viz., Nitrite, Ammonia, Nitrate, Phosphate, Total nitrogen and Silicate; Phytoplankton distribution (species composition, density); and Zooplankton distribution (species composition, density, biomass). These data were collected from shore to 10 km radius in 10 locations at Ghogha coastal waters during October 2020. Concentrations of nutrients viz., Nitrite (0.2-0.8 µmol/l), Ammonia (1.1- 2.7 µmol/l), Nitrate (4.5- 6.3 µmol/l), Phosphate (1.4-2.1 µmol/l), Total nitrogen (6.3-8.7 µmol/l) and Silicate (0.8-0.9 µmol/l) were of the normal range. Phytoplankton play a fundamental role in marine food webs but are affected by both natural and anthropogenic fluctuations in environmental conditions. To- tally, 49 species of phytoplankton were observed, comprising three groups viz., 39 species of diatoms, 8 species of dinoflagellates and 2 species of blue-green algae. Phytoplankton population density varied from 7800 to 13900 cells/l. Phytoplank- ton population mostly consisted of Bacillariophyceae (79.53%), Dinophyceae (15.9%) and Cyanophyceae (4.59%). Chaetoceros affinis was the dominant species followed by Trichodesmium erythraeum, Coscinodiscus centralis, Skeletonema costatum etc. Shannon - Wiener’s diversity index (H’) ranged from 4.44 to 5.02 (bits/ind.). Simp- son richness ranged from 0.951 to 0.967. Pielou’s Evenness index (J’) ranged from 0.947 to 0.981. Zooplankton comprised of 33 species. Copepods were the most diverse group, followed by decapods, ciliate groups, fish eggs and larvae, etc. Zoo- plankton abundance ranged from 60706 to 101484 individuals/100m3 and its biomass varied from 43.5 to 73.0 ml/100m3 . Most dominant species recorded were Acartia erythraea, Paracalanus parvus, Copepod nauplii and Acartia spinicauda. Shannon - Wiener’s diversity index (H’) values ranged from 3.85 to 4.53 bits/ind. Simpson richness ranged from 0.904 to 0.948. Pielou’s Evenness index (J’) ranged from 0.891 to 0.967. This study indicates that of shore to offshore region (10 km radius - 10 stations), nutrient, phytoplankton and zooplankton were maximum at 7 km radius, because of tidal influences and upwelling.

42 Marine Ecosystems and Biogeochemistry of the Ocean

Biophysical interactions over the tropical Indian ocean in a changing climate ORAL OSICON2021/249 Aditi Modi1 , Roxy M. K.1 , S. Ghosh2 1Indian Institute of Tropical Meteorology, Pune; 2Indian Institute of Technology Bombay

Marine primary productivity is central to the marine ecosystem processes and global biogeochemical cycles. The Indian Ocean has experienced the most significant surface warming amongst other tropical ocean basins during the past half-century. Previous studies have investigated the response of the marine ecosystem to ocean warming in the western tropical Indian Ocean and found that there is a reduction in marine primary productivity caused by warming of the ocean surface. The seasonal cycle of phytoplankton is very significant in the tropical Indian Ocean due to the semi-annual reversal of winds at the equator. Climate change is also expected to alter the seasonality of phytoplankton through modifications to the underlying physical drivers controlling bloom timing. This variability in the phenology of these phytoplankton blooms will affect the ecosystem dynamics with repercussions for the carbon export production and availability of food at higher trophic levels. This work aims to use satellite and in-situ observations along with a suite of model outputs (IITM-ESM and CMIP5) to understand the changes and variability in bloom tim- ings and abundance in response to the change in physical variables under a changing climate.

43 Marine Ecosystems and Biogeochemistry of the Ocean

Marine Algae : A Great Human Food Source QUICK ORAL Shreya Suresh Moraskar OSICON2021/253 Smt. Parvatibai Chowgule College Of Arts And Science, Gogol, Goa

One of the most significant fields of research in Food Science and Technology so far has been the extraction and characterization of innovative natural ingredients with biological activity that can contribute to consumers’ well-being as part of new functional foods. Nowadays, many individuals are just seeking minimally processed meals, this fact has sparked a significant deal of curiosity in discovering new items that can help us enhance our health and well-being. Also, ready-to-eat (RTE) foods are becoming increasingly popular among customers due to their low time and effort requirements. Oceans contain approximately half of the world’s biodiversity, making them a rich source of novel compounds and the greatest remaining store of beneficial natural molecules that may be utilized as functional ingredients in the food industry. However, natural bioactive compounds, especially those derived from marine creatures, have recently attracted more attention. Algae, one of the indispensable organisms in the world’s seas, are responsible for the majority of global organic matter creation through photosynthesis. Algae not only feeds the human body with the nutrition it requires to get through the day, but it may also contribute to making our world a more sustainable and healthier place to live. In contrast to other plant meals, algae contain a full amino acid profile, indicating that it is a complete protein. This implies that one of the most remarkable applications of algae is to assist human metabolic functions in ways that traditional plants may not be able to. Algae also contains a variety of nutrients, including minerals and trace elements that are needed for good health. Marine algal species have been reported as fascinating sources of various bioactive compounds such as polysaccharides, lipids, pigments and bioactive peptides.Several biochemical activities and possible health advantages of metabolites derived from marine algae are also studied. However, to establish algae as an efficient food that could complement traditional agriculture, there required more elaborated research to enhance biomass and nutrient concentration during marine algal cultivation. In addition, it is also essential to conduct proper clinical research to ensure the consumers’ safety. Overall, marine algae represent an opportunity to create a unique time-saving, safe, ready to eat, nutrient-dense functional meal that could contribute to meet ever-increasing demand of the world’s feed supply.

44 Marine Ecosystems and Biogeochemistry of the Ocean

A simple technique to mitigate microplastic pollution and its mobility (via ballast water) in the global ocean ORAL OSICON2021/256 Ravidas Krishna Naik1, Parthasarathi Chakraborty2, Priya M. D’Costa3, Anilkumar N.1, R. K. Mishra1, Veliton Fernandes4 1National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Goa; 2Centre for Oceans, Rivers, Atmosphere and Land Sciences, IIT Kharagpur; 3School of Earth, Ocean and Atmospheric Sciences, Goa University, Goa; 4Department of Biotechnology, Parvatibai Chowgule College of Arts and Science, Margao, Goa

Ballast water transport is considered as one of the major vectors for dispersal of microplastics around the global oceans. In this presentation, a simple, inexpensive solution has been proposed to reduce microplastic pollution and its mobility via ballast water. A screening chamber (with stainless steel three layered mesh) is proposed to be attached to the existing Ballast Water Treatment Systems (BWTSs) in cargo ships to filter back-flushed sea water from BWTSs. The three layered screens (500, 300 and 100 µm) will not only avoid clogging and easy separation of different size groups of microplastic particles but also help in smooth discharge of water to the sea. This technique is anticipated to accumulate ∼6.5 million microplastic particles from a single voyage and considering the daily turnover (0.033 billion tonnes) of ballast water, it is possible to collect ∼1 to 1.3 metric tonnes of particles/day. It is therefore, suggested that use of this proposed technique, along with other region- specific ocean cleaning initiatives, will help in mitigating microplastic pollution in the global ocean.

45 Marine Ecosystems and Biogeochemistry of the Ocean

Application of machine learning to predict the copepod-bacterial association QUICK ORAL Balamurugan Sadaiappan, Manguesh U Gauns OSICON2021/257 CSIR-National Institute of Oceanography, Dona Paula, Goa

In recent decades, the application of Machine learning (ML) has grown into an important research topic in the diverse field. Providing an intelligent solution to problems that are challenging to solve by other statistical methods. ML, a data- driven technique, where the computer learns from the input data and built a model to predict and analyse another part of the data. With the steady advancement in technology, especially in DNA sequencing, the amount of data and data dimensions raised. Using traditional bioinformatics analysis techniques to analyse vast volumes of data has some limitations. The new advancements in machine learning have solved these limitations. ML also applied in solving many biological issues such as the identification of marine species from plankton to mammals. In our study, we have adopted the unsupervised machine learning algorithm, like Random forest (RF) and Gradient Boosting (GB) to predict the important bacterial (core-OUTs) associated with the copepods. We applied a feature selection parameter to predict the important bacteria from the 16 million copepod’s associated bacterial sequence (16S rDNA). Among the unsupervised machine learning, GB showed better prediction accuracy, and solved the long- standing question in copepods associated with bacteria’s. For the first time, we predicted eight and four bacteria as important in Pleuromamma spp. and Calanus spp. respectively. Also, our meta-analysis confirms that copepods gut a hot spot for the biogeochemical cycle. Bacterial community with the potential gene for methanogenesis and nitrogen fixation was high in Pleuromamma spp., while bacterial community with potential genes for assimila- tory sulphate reduction and cyanocobalamin synthesis found high in Temora spp.. Future perspective, ML algorithms a promising application to predict the impact of environmental factors on marine organisms.

46 Marine Ecosystems and Biogeochemistry of the Ocean

Variability in diatom frustule and dinoﬂagellate cyst in the short sediment coresfrom two locations in the eastern Arabian Sea ORAL OSICON2021/260 Medhavi Pandey, Haimanti Biswas, Maria Hilda Joao CSIR National Institute of Oceanography, Biological Oceanography Division, Dona Paula, Goa

The eastern Arabian Sea (EAS) is a perfect hotspot for studying well preserved organic matter (OM) in sediments as the persistent oxygen minimum zone (OMZ) helps in preserving OM which is used for reconstructing the past changes in the water column. However, studies reconstructing past phytoplankton communities from the sediment cores are extremely rare from the Indian shelf region, yet highly important due to its rapidly changing nature both in turns of anthropogenic and climate-related forcing. Such a palaeo-proxy study can be complementary to the monitoring studies to understand the changes in the phytoplankton community to inorganic nutrient loading in the past and their impacts to predict future changes. The current study used diatom frustules (DF) and dinoflagellate cysts (DC) from two short sediment cores (collected from 500 m water depth along the Gujarat and Goa coasts from the OMZ) along with inorganic nutrients in the top 5 cm. The age of the top 5 cm of cores was determined using 210Pb dating which corresponded to ∼100 years before present. The result depicts a clear trend of increasing DF abundance over DC (high Diatom: Dinoflagellate) for both the cores in recent years. It was observed that DC abundance decreased and DF abundance increased significantly in the off Gujarat location over the last 60 years. While again a similar trend of increased DF and decreased DC was observed from Goa over past a century. Also, significant variability in the ratio of centric: pennate diatom was noticed within this period in the north; whereas a noticeable increase in the relative% of pennate over centric diatom was also observed over this period in the Goa region. A principal component analysis (PCA) was conducted including all ancillary parameters and it was noticed that these changes in DF: DC ratio as well as pennate: centric was related to nitrogen and silicate levels. This is a preliminary study and further analysis is underway to infer more from this study.

47 Marine Ecosystems and Biogeochemistry of the Ocean

Sea foam: A unique habitat in the marine Ecosystem QUICK ORAL Meenakshi1, Priya M. D’Costa2 OSICON2021/288 1Department of Microbiology, Goa University, Goa; 2School of Earth, Ocean and Atmospheric Sciences, Goa University, Goa

Foam is a natural phenomenon that is observed in aquatic environments such as lakes, rivers and seas. Foam is composed of water, air, some naturally occurring organic matter, fatty acids, proteins, that are produced by phytoplankton, microalgae and bacteria. These organisms also produce surfactants that interfere with the surface tension of water, thereby allowing mixing of water and air and stabilization of the foam bubbles. In India, the phenomenon of sea foam production in water bodies has been observed at many sites. For example, (a) sea foam incident in Marina Beach, Chennai in 2019 (b) Sea foam observed in Hole Beach, Goa in 2019; and (c) Foam formation in Bellandur lake, Bengaluru in 2017. All these incidents were found to be linked with a point source of pollution and anthropogenic activities. This type of foam can cause many environmental problems. Foam from such sites is also rich in harmful pollutants such as heavy metals, pesticides and antibiotics. Interestingly, sea foam is considered a ’nutrient-rich’ island for many aquatic and terrestrial organisms. It is home to a wide variety of organisms such as Phaeocystis pouchetti; bacteria such as Escherichia, Enterococcus, Vibrio, Salmonella, Klebsiella; fungi such as Dendryphiella arenaria, Varicosporina ramulosa; insects such as Halobates; and tunicates. Sea foam is also being recognized as a reservoir for human pathogens. In marine environments, heavy metal pollution due to anthropogenic activities can act as an agent for co-selection of antibiotic resistance in sea foam communities, thus posing a threat to human health. Apart from harmful consequences, foam communities also have biotechnological potential. Foam organisms have a characteristic feature of producing biosurfactants which are known for their solubility and cleaning properties. They have vast potential in detergent-producing industries. Foam communities can also be explored for their applications in bioremediation, wastewater treatment plants, pharmaceuticals and oil industries.

48 Marine Ecosystems and Biogeochemistry of the Ocean

Algicidal bacteria as a promising candidate for control of harmful algal blooms ORAL OSICON2021/296 S. V. Sandhya Biological Oceanography Division, CSIR- National Institute of Oceanography, Goa

Being primary producers in the aquatic environment, algae and cyanobacteria contribute substantially to the aquatic food web. Though seasonal algal blooms are important from an ecological point of view, the public health and economic impact of these phenomena is on the rise during last few decades. According to Inter- national Council for the Exploration of the Seas, phytoplankton blooms generally include foam production, visible discolouration of the waters, toxicity to humans or fish and invertebrate mortality. Important factors attributing increase in blooms include pollution, eutrophication of coastal environment due to increase in anthropogenic activities, bioinvasion of exotic species through ship ballast water, global warming and wind effects. Recurrence of harmful algal blooms can lead to serious constraint to the development of coastal areas due to their adverse impact on ecosystem as well as on human health. Thus, a coordinated scientific and management approach is essential to minimize the manifestation and intensity of algal blooms. Major drawbacks of physical and chemical bloom control methods include their higher cost and immediate threatening effect on environment and non-target aquatic species. Hence, application of biological control agents is considered as a promising alternative approach for controlling algal blooms. Algicidal bacteria that can associate to microalgae have the capability to control the proliferation of these harmful algae. The major bacterial groups included Alteromonas, Cytophaga, Xanthomonas, Pseudomonas, Alcaligenes, Saprospira etc. These algicidal bacteria can dwell on resources that released after algal cell death and lysis and have a massive impact on productivity of aquatic ecosystem by modulating entire communities. Despite resource availability, these dynamic processes might be influenced by hydrographic variables such as temperature, pH and dissolved oxygen. Gener- ally, the algicidal bacteria are effective through either by the release of algicidal compounds in the environment or by the microalgal cell lysis. Nevertheless, it was found that most identified algicidal bacteria eliminate algal cells through secreting active metabolites. The commercial application of algicidal bacteria is rather limited at this moment owing to the difficulty of isolation and purification of these active metabolites. Hence, more elaborated studies on algicidal microbiome would open up avenues to develop an environment friendly prevention strategy for toxic algal blooms.

49 Marine Ecosystems and Biogeochemistry of the Ocean

The ﬁrst report on spatio-temporal distribution of Chromophoric Dissolved Organic Matter (CDOM) in Chilika, the largest coastal lagoon in India QUICK ORAL Susmita Raulo, Sambit Singh, Tamoghna Acharyya OSICON2021/298 School of Sustainability, XIM University, Bhubaneswar

Coloured dissolved organic matter (CDOM) is the optically measurable component of dissolved organic matter in water. CDOM is found naturally in aquatic environments and is a complex mixture of many hundreds to thousands of individuals, unique organic matter molecules, which are primarily leached from decaying detritus and organic matter. The CDOM dynamics are expected to be highly variable due to the biogeochemical complexity of the study region and the season. CDOM is gaining greater attention for their photochemistry and photobiology activity in the aquatic ecosystem by a bsorbing the ultraviolet (UV) and short-wavelength blue portions of the light. The concentration of CDOM can have a significant effect on biological productivity in aquatic systems. However, virtually no studies have focused on the variability of CDOM concentration on coastal wetlands. These can be rapidly analyzed by employing a UV-VIS spectrophotometer, which is more accurate, cost- effective, seamless & capable of giving high-frequency monitoring of water quality health. In this abstract, we present the first-ever report on the Spatio-temporal distribution of coloured dissolved organic matter in the largest coastal lagoon in India. The CDOM data was also supported by various water quality data. These data enabled us to further investigate the controlling mechanisms for the distribution of CDOM across the four ecological zones/sectors of the lagoon. Our preliminary data suggest that the Concentration of CDOM was higher in the Northern sector followed by the Central sector, Southern sector, and Outer channel. The lagoon generally receives marine as well as freshwater influx through rivers/rivulets/terrigenous runoff and adjoining ocean, respectively. It was observed that the CDOM concentration was higher in the Northern sector due to the influence of fresh water and the presence of macrophytes. CDOM concentration was very low in the outer channel due to the higher saline condition by directly connect with the Bay of Bengal. In Central sector the CDOM concentration showing moderate value due to the brackish water condition.

50 Marine Ecosystems and Biogeochemistry of the Ocean

The Observed Variability of Dissolved Oxygen, Chlorophyll and CDOM along the South Eastern Arabian Sea waters ORAL OSICON2021/299 Deepulal P. M., AnilKumar K., Harikrishnan M., Raghunadha Rao A., Akhil V.S. DRDO-Navel Physical and Oceanographic Laboratory, Ernakulum, Kerala

The study of oxygen minimum zones and its impact on ﬁsheries and global climate change is very important in the South Eastern Arabian Sea (SEAS). Due to scarcity of observed dataset, ﬁeld campaign along the transects 80, 90 & 100N in the SEAS carried out to understand the spatial and vertical distribution of dissolved oxygen, chlorophyll and CDOM during the period of Nov 16th to 22nd 2020 onboard INS

Sagar dhwani. Data analysis revealed oxygen concentration as low as 0.1 ml O2/L is observed at bottom layers (200-500m) in the SEAS. The dissolved oxygen varied from 3-5 ml O2/L in the surface layers and drastically declined to 0.1 ml O2/L. This comparative high oxygen levels in upper layers leads to high productivity in the surface isothermal layers (20m-80m depth) resulting high chlorophyll. This chlorophyll sinks deeper depth and gets decomposed at that level. The decomposition in 200- 500m is an aerobic process depleting oxygen resulting in oxygen minimum zones. As a result, like other oceanic areas, the water column in the Indian Ocean especially Arabian sea also contains mid-depth O2 concentration minima, maintained by a combination of relatively high O2 demand by microbes that decompose organic matter sinking from the surface, and restricted O2 supply as a result of sluggish deep-water circulation and mixing. This oxygen minimum zones may initiated the denitriﬁcation processes in the mid-depth, which release nitrous oxide a potential greenhouse gas causing the global climate change. So this study will give the insight knowledge about the vertical distribution of dissolved oxygen and related process in SEAS.

51 Marine Ecosystems and Biogeochemistry of the Ocean

Biotechnological Potential of Diatoms QUICK ORAL Harsha Gaonkar, Priya M. D’Costa OSICON2021/307 School of Earth, Ocean and Atmospheric Sciences, Goa University, Goa

Diatoms are one of the predominant phytoplankton groups in aquatic environments. They have a ubiquitous distribution and occur in both, freshwater and marine environments. A notable feature of diatoms is their photosynthetic nature. Due to this, diatoms form the base of food webs in aquatic environments and play important roles in sustaining the food web and resident fish populations. Other than this ecological significance, diatoms have also been explored for their biotechnological potential. Diatoms can grow with simple inorganic nutrients and harvest energy from sunlight, finally building up biomass. This is a huge advantage that supports their biotechnological potential, as it offsets the need for expensive media requirements, usually required for cultivation. This poster details the biotechnological applications of diatoms. Diatoms have an intricate silica frustule, which is finely detailed at the nano-scale. Understanding the processes by which diatoms build this intricate frustule provides insights relevant to nanobiotechnology. Diatoms have also been investigated for their production of biomaterials, nanoparticles and complex metal nanostructures; and as vehicles for drug delivery and gene delivery. Diatoms are also prolific sources of metabolites that have relevance as biofuels, nutraceuticals, anti-oxidants, vitamins, animal feed and vegetarian protein supplements. Diatoms are also used as environmental indicators and for biosensing purposes. Thus, these microscopic organisms have biotechnological applications in diverse fields and should be considered for commercial exploitation.

52 Marine Ecosystems and Biogeochemistry of the Ocean

Distribution of microplastics in coastal regions of India QUICK ORAL Blossom Dias1, Varada S. Damare1,2 OSICON2021/308 1Department of Microbiology, Goa University, Goa; 2Marine Microbiology Program, School of Earth, Ocean and Atmospheric Sciences, Goa University, Goa

Microplastics (MPs) are the particles <5 µm in size that pose threat to different ecosystems. Due to their small size, they are incorporated into biogeochemical pathways and food webs of marine water column and sediments. Various toxins can be transported and introduced into water by microplastics, the surfaces of MPs are colonized by microorganisms forming biofilms which results in change of surface morphology of MP including topography, roughness, surface area, density etc. The threats mostly associated with MPs are release of toxic chemicals, ingestion by marine biota, transportation of alien invasive species and pathogenic organisms. Plastic waste management in India is quite challenging as conventional techniques like mass burning, landfilling and open dumping are practiced. The concentration of MPs in different samples from different habitats in India varies considerably. Polyethylene terephthalate (PET) was found to be one of the most abundant MPs after polyethylene (PE) on the beaches. Along the west coast of India, occurrence of MPs was reported in the entire coastal stretch. Their abundance in Kerala waters ranged between 0.22 and 3.58 particles/m−3. Their occurrence along the coast of Goa was found to be higher during monsoons than other times of the year. PE and polypropylene (PP) were the dominant polymers here. Along the east coast of India, the surface water of Tuticorin had greater MPs than that of Chennai. When Mumbai, Tuticorin and Dhanushkodi samples were compared, mass of MPs ranged between 1.05 to 3.54 m kg−1 of sand, and Mumbai showed higher abundance than the other two. Three estuarine sediments from Tamil Nadu also showed the presence of MPs. Impact of flood on MPs abundance showed three-fold higher numbers post- flood than pre-flood time in the surface sediments near Chennai. India has now come up with different management guidelines to set awareness and limit the use of MPs like ban of single use plastic and ban of microbeads in personal care products.

53 Marine Ecosystems and Biogeochemistry of the Ocean

Oil spill in marine environment and associated microbiology QUICK ORAL Mrinalini Chandra Mohan1, Varada S. Damare1,2 OSICON2021/309 1Department of Microbiology, Goa University, Taleigao Plateau, Goa ; 2Marine Microbiology Program, School of Earth, Ocean and Atmospheric Sciences, Goa University, Goa

Crude oil which is the liquid form of petroleum is considered as a Hazardous waste and makes its way into the marine environment through various natural and anthropogenic sources. The oil that enters the water column, either gets dispersed in the littoral zone of the water column or remain on the surface. If the oil does not get dispersed it ends up harming the coastal organisms, but if it gets dispersed it ends up affecting many marine organisms such as microorganisms, fish larvae, benthic organisms etc. These organisms bring about the bioaccumulation and biomagni- fication of the oil up the food web. Oil causes heavy toxicity in these organisms and affects their physiology. In marine mammals such as sea otters the oil causes smothering of the fur because of which these organisms are forced to increase their intake of food to maintain core body temperature. The oil also causes smothering of the feather of shore birds and makes it difficult for the bird to fly. In the case of microorganisms, oils spills trigger a change in the composition of the natural mi- croflora of the water column and hence microorganisms that show various adaptive responses tend to survive in oil spill affected regions. These microorganisms show the presence of a wide range of degradative enzymes and can hence play a major role in treatment of oil spills. A number of microorganisms can show adaptive measures such as resistance to the presence of oil, elimination of ingested hydrocarbon, showing stimulated growth in the presence of oil. A few microorganisms also behave as biological dispersants and bring about natural dispersion of crude oil droplets.

54 Marine Ecosystems and Biogeochemistry of the Ocean

Accumulation of Petroleum Hydrocarbons in Zooplankton at Nagapattinam coastal water, Bay of Bengal, South East coast of India ORAL OSICON2021/317 Srinivasan Sundararajan1, Mukunda Kesari Khadanga2, Balasubramanian Kamalakannan3, Asim Amitav Pattanayak2, Basanta Kumara Jena1 1Earth System Sciences Organization (ESSO) - National Institute of Ocean Technology (NIOT), Chennai; 2Marine sciences department, Berhampur University, Berhampur, Ganjam, Odisha; 3Madurai Kamaraj University, Madurai, Tamil Nadu

The present study deals with the distribution of petroleum hydrocarbon in seawater and their levels in a zooplankton samples. Sampling operation of seawater and zooplankton samplers were collected from six stations, along each three stations of Nagapattinam coastal region and inside harbor area during 2016. The different sampling stations were characterized to present different types of pollution, station 1 is located near the mouth of fishery harbor. Water samples were collected at 0.5 m below water surface, using Niskin water sampler. Dissolved and dispersed petroleum hydrocarbons were extracted with a mixture of n-hexane, di-chloro methane (1:1 v), and evaluated by spectrofluorimetric technique, the precision is 5% for petroleum hydrocarbon concentration of 10 µg/l. Zooplankton samples were collected using a WP2 plankton net (200µm), they were filtered on Whatman GF/A pretreated filters at 400oC for 2 hours and extracted later by a mixture of n-hexane, Acetone (8:2 v) in Soxhlet apparatus. The fluorescence of different extracts was determined using Spec- tro fluorimeter and chrysene as an intercomparison chemical standard. Petroleum hydrocarbons concentrations were ranged between 1.2 µg/l and 8.1 µg/l in seawater and between non detectable values and 1146 µg/g dry weight in zooplankton samples. The maximum values were recorded in both water and zooplankton samples of station 1 reflecting an important impact of the harbor and urban runoff waters on the coastal ecosystem. The relation between concentration of petroleum hydrocarbon in water and in zooplankton are showed the positive correlation. The results reveled the spatial variation of concentration among the sites.

55 Marine Ecosystems and Biogeochemistry of the Ocean

Spatiotemporal distribution of diatom community with distinct salinity regimes along the Kali estuary, Karwar, West Coast of India QUICK ORAL Akshata Naik, Shivakumar Haragi OSICON2021/336 Department of Studies in Marine Biology, Karnatak University Dharwad, Post Graduate Centre, Karwar, Karnataka

Seasonal variations in the composition of diatom were investigated monthly basis at 3 different salinity gradients zones along the Kali estuary from February 2017 to Jan- uary 2018. A total of 63 diatom species belonging to 29 family were identified during the study period. Among the diatom groups, centrales (57%) were dominated over pennales (43%). The most diverse genus were Chaetoceros (8 species), Rhizosolenia (5 species), Pleurosigma (5 species) and Nitzschia (4 species) respectively. Zone 1(56 species) representing the highest species diversity compared with zone 2 (29 species) and zone 3 (21 species). Rhizosolenia sp., Palmerina sp., Coscinodiscus sp., Melosira sp., Chaetoceros sp., Fragilaria sp., Thalassionema sp., Pleurosigma sp., Gyrosigma sp., Pseudo-nitzschia sp., Nitzschia sp., Bacillaria sp. and Entomoneis sp. were observed from all the studied zones indicating its wide range of salinity lenience. A total of 12 harmful algal bloom-forming species, have been identified. With this study it is to conclude that Kali estuary representing higher diatom diversity and salinity will be the limiting factor for diatom distribution. Diatoms play an important role in estuarine food web; hence periodical monitoring of these microalgae is crucial in ecological assessments.

56 Marine Ecosystems and Biogeochemistry of the Ocean

Ingression and seasonal abundance of Decapoda Larvae along the Kali estuary, Karwar, West Coast of India QUICK ORAL Rajeshree Pednekar, Shivakumar Haragi OSICON2021/337 Karnatak University Dharwad, Department of Studies in Marine Biology, Post Graduate Centre, Kodibag, Karwar, Karnataka. India

Seasonal abundance of commercial important Decapoda larvae were studied along the Kali estuary(20km), Karwar, Karnataka, West coast of India in accordance to lunar and tidal phases. Hydrological parameters such as Salinity, pH, Dissolved oxygen and Water temperature were recorded concurrently for a period of 13 months (January 2018 to January 2019) along the estuary. Based on the salinity gradient, two sampling zones were demarcated. Zone 1 influenced by high tidal amplitude and salinity ranged from 35 to 21 ppt wherein, Zone 2 is an upstream area of the estuary with less tidal influence along with mangrove vegetations. Larval samples were collected fortnightly during flood and ebb tides of new moon and full moon. Larval samples were collected from 0.5 m diameter conical plankton net of 0.33mm mesh size. The sampled larvae belonged to Penaeidae (nauplius, zoea, mysis and post larvae), Caridea (zoea and post larva) and Brachyura (zoea and megalopa). Dominant larvae being Brachyura (zoea) followed by Penaeidae (zoea and mysis) during the full moon and new moon phases of flood tide. The seasonal larval recruitment and abundance were maximum in zone 2 and post- monsoon season represented 59%, pre-monsoon 27% and monsoon 14% larval forms. Hence, Kali estuary typically shelters variety of the larval forms which strengthens the estuarine food web and associated fisheries.

57 Marine Ecosystems and Biogeochemistry of the Ocean

Application of CROCO+NPZD model to simulate the coastal biochemical variability ORAL OSICON2021/340 D Sathish Kumar, Uma Sankar Panda, Umakanta Pradhan, Pravakar Mishra, M. V. Ramana Murthy National Center for Coastal Research, Ministry of Earth Sciences, NIOT Campus, Chennai

Numerical models validated against in-situ observations provides a detailed account on the regional to micro scale processes and controlling factors of each variable with reasonable accuracy for use in planning and management. In this study, Coastal and Regional Ocean COmmunity model (CROCO), built around the kernel of ROMS (AGRIF), has been configured at very fine resolution 500m and 30 vertical sigma layers coupled with biogeochemical model and forced with ERA5 for atmospheric forcing and Copernicus Marine Global Forecast Products for physical and biochemical boundary conditions to simulate the coastal hydro-ecological processes along southeast coast of India. The simulated temperature, salinity, dissolved oxygen, chlorophyll-a and nitrate are validated with CTD and in-situ data. The skill analysis for temperature and salinity profiles at different spatiotemporal scale have correlation coefficient of 0.8 to 0.9, and RMSE between 0.1 and 0.4. Although the amplitude of the simulated biochemical variables is underestimated, it captures the seasonal trends, upwelling, and phytoplankton bloom that occurred during the study period. Data assimilation from coastal buoys, improved boundary conditions and inputs from land runoffs will enhance the model performance. The study shows that CROCO, an open-sourced community model, is a potential tool to demonstrate the ocean dynamics for coastal applications where understanding and predictability of ecological processes are important for the coastal communities.

58 Marine Ecosystems and Biogeochemistry of the Ocean

The Preliminary study of coastal water acidiﬁcation monitoring in the Palk Bay, Southeast coast of India ORAL OSICON2021/341 Balasubramanian Kamalakannan1, Srinivasan Sundararajan2, Basanta Kumara Jena2, Asim Amitav Pattanayak3, Mukunda Kesari Khadanga3 1 Madurai Kamaraj University, Madurai, Tamil Nadu; 2 Earth System Sciences Organization (ESSO) - National Institute of Ocean Technology (NIOT), Chennai; 3 Marine sciences department, Berhampur University, Berhampur, Odisha

The Ocean is a living paradise in the present scenario of the earth’s and it is one of Earths most valuable natural resource. It provides a treasured source of recre- ation for humans. It is mined for minerals and drilled for crude oil and gas. The ocean plays a critical role in removing carbon from the atmosphere and providing oxygen. It regulates Earth’s climate. The study was carried out to know the coastal water quality (Gulfs) in order to find out the CO2 solubility and saturation chemistry of carbonates. The study was carried out at the selected sites from the Palk Bay region, south east coast of India. Water and sediment samples were collected monthly for acidification studies and seasonally for metals, for three seasons such as monsoon, post-monsoon and pre-monsoon during study period. The range of water temperature, pH, salinity and dissolved oxygen were recorded during the study period respectively 26.3 - 32.9◦C, 7.54 - 8.06, 16.1- 37.4 PSU and 2.5 - 8.44 mg/L in the selected sites. The range of calcium carbonate saturation (Ω) values were recorded from 0.46 - 4.29. Trace metal in the sediments ranged from Ni (3.21 - 5.95 (µg/g), Co (2.35 - 4.07 µg/g), Cu (33.05 - 50.49 µg/g), Cd (0.19 - 0.45 µg/g), Pb (16.5 – 33.3 µg/g), Mn (101 – 140 µg/g), Zn (155 – 207 µg/g). The carbonate saturation in water and metals in sediments were showed spatial as well as seasonal variation among the sites in the study area. The study reveals that the Palk Bay region requires a long term monitoring of coastal water quality to know the impact of acidification and climate change for the calcifying organisms.

59 Marine Ecosystems and Biogeochemistry of the Ocean

Evaluation of the heavy metal pollution in the estuarine ecosystem of Tapi and its sustainable management, Arabian Sea ORAL OSICON2021/342 Mukunda Kesari Khadanga1, Balasubramanian Kamalakannan2, Asim Amitav Pattanayak1, Srinivasan Sundararajan3, Basanta Kumara Jena4 1 Marine Sciences department, Berhampur University, Berhampur, Odisha 2 Madurai Kamaraj University, Madurai, Tamil Nadu; 3 Earth System Sciences Organization (ESSO) - National Institute of Ocean Technology (NIOT), Chennai

Present study, to evaluate the heavy metals pollution in the surface sediment of Tapi Estuary, Arabian Sea. Now a days heavy metal accumulation in the sediment is a sensitive issue for aquatic organisms due to the industrial and anthropogenic activities. Surface sediment samples were collected nine sites along the Tapi estuary during 2015. The range of metal concentration in the study area are observed in 48.17 - 87.24 µg/g for Pb, 47.76 - 87.65 µg/g for Cr, 96.78 - 172.65 µg/g for Zn, 69.98 - 112.34 µg/g for Ni, 114.56 - 189.76 µg/g for Cu, 0.85 - 2.12 µg/g for Cd, 16.76 - 32.45 µg/g for Co. The metals are decreasing order from upstream to downstream.The factor analysis resulted that, Positive loading of cadmium (Cd), chromium (Cr), Nickel (Ni), lead (Pb) and Zinc (Zn) in the study region. So, these are found potential environmental risk based on sediment quality guidelines (SQGs) due to the influence from the industrial and anthropogenic sources. Enrichment factors (EF) found that the Pb and Cd are fair enrichment in and around the estuary, whereas other metals Cr, Ni, Zn, Co, and Cu show significant to very high enrichment. Geo- accumulation index (Igeo) results revealed that moderately to highly polluted with respect to Cd, Pb and Zn and the Co, Cu and Cr shows high to very highly polluted along the study site. Pollution load index revealed that the sampling sites in the upstream sediment were more polluted than downstream estuarine because of the influence of industrial and anthropogenic. Hence the result suggested that inputs need to be monitored further in the long-term basis for isotopic sediment dating to reconstruct the contamination history for the ecosystem modeling, sustainable ecosystem, and coastal zone management.

60 Marine Ecosystems and Biogeochemistry of the Ocean

Development of a coupled physical biogeochemical model for the Indian Ocean ORAL OSICON2021/346 Anju Mallissery1,2, Vinu Valsala1, Prajeesh A G1 1 Indian Institute of Tropical Meteorology, Pune; 2 The Department of Meteorology and Oceanography, Andhra University

The Northern Indian Ocean (NIO) is a very dynamic ocean that is significantly influenced by seasonal monsoon winds and currents. The strong regional and temporal variability in NIO translates into an even larger variability in biological productivity and species diversity. A 3D coupled physical-biogeochemical model based on North Pacific Ecosystem Model for Understanding Regional Oceanography (NEMURO), Ocean Dynamic Thermodynamic Model (ODTM), and Mixed Layer Model (MLM) with nitrogen and silicon cycles are developed for the NIO with a special focus on the Arabian Sea (AS). The physical model consists of ODTM, a Reduced Gravity Model (RGM) with 5 1/2 layers which is coupled with a MLM for parameteriz- ing the fine mixing at the surface ocean. The model is implemented to investigate the role of nitrogen (nitrate + ammonium) versus silicate limitation on plankton biomass. The seasonal cycle of plankton biomass, physical parameters, mixed layer depth, and nutrients are well simulated by the model along five selected bio-Argo tracks in the AS during a period from 2013 to 2016. Further, three sensitivity simulations are conducted by suppressing (1) new production of flagellates and diatom (2) regenerated production of flagellates and diatom, and (3) silicate availability for diatom production. The new production represents ∼50% of the total primary production in the AS and controls ∼30% of total secondary production annually. The regenerated production augments small phytoplankton (by ∼40%; e.g., flagellates) and small zooplankton (by ∼15%; e.g., ciliates) growth with negligible effects on large phytoplankton (e.g., diatom) and predatory zooplankton (e.g., copepods). The silicate limitation is identified as the primary limiting nutrient which keeps the diatom production within the observed range. The diatom production is co-limited by both nitrogen and silicate at the surface (<40m) with a dominant limitation from nitrogen from March to June and October to November. In the subsurface, silicate is identified as the dominant limiting nutrient for diatom production throughout the year.

61 Marine Ecosystems and Biogeochemistry of the Ocean

Determination of Bioaccumulation in Marine Ecosystem by Laser induced Breakdown Spectroscopy ORAL OSICON2021/350 Della Thomas1, S. Surendran1, N. J. Vasa1,2 1 Department of Ocean Engineering, Indian Institute of Technology, Madras; 2 Department of Engineering Design, Indian Institute of Technology, Madras

Marine biofouling refers to the undesirable growth and adhesion of marine organisms such as barnacles, macroalgae and microbial slimes on immersed structures. Biofouling composition is determined by collecting samples from marine structures and vessels and analyzing them in laboratories. Alternatively, an approach of online sensing based on Laser Induced Breakdown Spectroscopy (LIBS), which consists of analysis of the spectral emission from laser-induced plasma, can be considered for the elemental composition of biofouling. The elements Na, K, Mg, Ca, Al, Fe, Zn, B, Sr, Si, Ba, C, H, N, S and O were observed through LIBS analysis for the biofouling sample grown on FRP and SS substrate for various stages of its growth. The major matrix elements were observed to be Mg, Ca and K with the other elements viz. Na, Al, Fe, Zn, Sr, Si, Ba, C, H, N, S and O in trace levels. The presence of most of these species in LIBS spectra was also conﬁrmed based on the ICP-OES and CHNS-O analysis for fouling samples grown on FRP and SS substrate.

62 Marine Ecosystems and Biogeochemistry of the Ocean

Two New Carnivorous sponge (Porifera, Cladorhizidae) species from the Central Indian Ridge Seamounts ORAL OSICON2021/357 Periasamy R., P. J. Kurian, B. S. Ingole National Centre for Polar and Ocean Research (NCPOR), Ministry of Earth Sciences, Goa

Deep-sea sponges are an imperative component of benthos. They accumulate the suspended organic matter by ﬁltering large quantities of water and with their intricate structures, provide the most suitable habitats for various associated organisms. In this communication, we described two new species of the deep-sea sponge belong to the family Cladorhizidae from the Central Indian Ridge (CIR), Indian Ocean. The family Cladorhizidae is very important in the class Demospongia. Even though the representatives of the Cladorhizidae family are recorded worldwide, they are predominant in the deep sea. The sponge specimens are part of the benthic sledge collection conducted onboard the RV MGS Sagar in the CIR region during the hydrothermal exploration cruise (MGS36/37- March-May 2020). A detailed taxonomic description of two novel species Asbestopluma (Asbestopluma) sp.Nov1; Asbestopluma (Asbesto- pluma) sp. Nov 2; is provided based on the morphological and molecular (COI and 28S) data. In addition to the description of two new species, the occurrence of another carnivorous sponge (Chondrocladia (Chondrocladia)) burtoni Tendal, 1973), previously known only from the Atlantic and Antarctica is reported ﬁrst time from this region. The systematic positions of the two new species are discussed based on the structural and phylogenetic analysis. This study highlights the importance of seamount benthic habitats for supporting the rich and diverse sessile fauna of the CIR and their impending genetic connectivity with other oceanic regions.

63 Climate change (CC)

Sessions’ Chairman

Dr. D. Bala Subrahamanyam, SPL Space Physics Laboratory, Thiruvananthapuram, Kerala

Dr. Supriyo Chakraborty Indian Institute of Tropical Meteorology (IITM), Pune, Maharashtra

64 Climate change (CC)

Invited Talk

INVITED TALK: Climate change and the seas around us: India and the Ocean

Dr. Raghu Murtugudde

University of Maryland, USA Climate change

Future Projection of Indian Ocean Temperatures Under Global Warming QUICK ORAL A. Anusree1,2, M. K. Roxy1 OSICON2021/15 1Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune, India; 2Department of physical oceanography, Cochin University of Science and Technology, Cochin

Oceans have absorbed more than 93% of the additional heat due to anthropogenic emissions, with the Indian Ocean recording a rapid warming during the recent decades. The SST in the Indian Ocean has warmed by about 0.75◦C in the past 151 years and continue to increase in the future higher emission scenarios. The current study evaluates the future projections of Indian Ocean sea surface temperatures (SSTs) using the Coupled Model Intercomparison Project phase 6 (CMIP6). CMIP6 projections for the period from 2020 until the end of the 21st century is examined, and the changes are compared with respect to the historical simulations and observed data. Multi-model ensemble mean of CMIP6 projections indicate a very likely warming of 1◦C under SSP1-2.6 (lower), 1-2◦C under SSP2-4.5 (medium) and greater than 2.5◦C under SSP5-8.5 (higher) emission scenarios with respect to the historical simulations, by the end of the 21st century, in the tropical Indian Ocean. SST tends to ﬂatten only in lower emission scenarios where mitigation strategies are adopted highly. The interannual variability in the observed Indian Ocean SSTs is largely regulated by El Ni˜noSouthern Oscillation (ENSO), as the dominant model of variability. However, in the higher emission scenarios, basin-wide warming emerges as the dominant mode of variability. Though the warming is projected to be basin- wide, the strength of the warming is non-uniform, with an enhanced trend over the northwestern part and a subdued trend over the southeastern Indian Ocean. The frequency of positive IOD events is also projected to increase, as one in every 5.67 years by the end of the 21st century.

66 Climate change

Performance of COWCLIP Signiﬁcant Wave Height datasets and Extreme Wave Height Projections for the Indian Ocean QUICK ORAL Athira Krishnan1, Prasad K Bhaskaran1, Prashanth Kumar2 OSICON2021/20 1 Department of Ocean Engineering and Naval Architecture, Indian Institute of Technology Kharagpur; 2Department of Applied Sciences, National Institute of Technology Delhi

Increasing evidence suggests that global climate change will alter wind sea and swell waves, modifying the severity and frequency of coastal flooding and the impacts of sea level rise. Numerous studies have addressed the projected changes in significant wave height for the Indian Ocean (IO) region, and there is a need to conduct thor- ough performance evaluation of global climate models (GCMs) over this region for futuristic planning. With this motivation, the present study examined the performance of historical dynamical wave climate simulations generated under the Coordi- nated Ocean Wave Climate Projections (COWCLIP) experiment. The simulations utilized near-surface wind speed datasets from 8 CMIP5 (Fifth phase of Coupled Model Intercomparison Project) GCMs to force a spectral wave model. The skill level of individual GCM forced wave simulations and multi-model mean (MMM) in reproducing the significant wave height (SWH) over four different sub-domains in the IO was evaluated with reference to the ECMWF Reanalysis 5th Generation (ERA5) datasets. Several performance metrics such as the Taylor Skill, M-Score, Model Climate Performance Index (MCPI), and Model Variability Index (MVI) are employed to establish the skill level of model simulations. The study deciphers that model performance is highly reliant on the region and its characteristics. Repre- sentation of the historical wave climate over the Arabian Sea (AS) and the Bay of Bengal (BoB) regions is remarkable in the COWCLIP datasets. However, there are discrepancies noticed in SWH distribution over the South Indian Ocean (SIO) attributed to model limitations in adequately reproducing swell wave fields over that region. The MMM constructed using the best-performing models (MRI-CGCM3, ACCESS1.0, INMCM4, HadGEM2-ES, and BCC-CSM1.1) is found consistent at all the sub-domains. The monthly maxima are fit to the generalized extreme value (GEV) distribution to estimate the extreme SWH from the 20 years wave simulation. Projected mean and extreme SWH for the mid century (2026-2045) and end century (2081-2100) under the medium (RCP 4.5) and worst (RCP 8.5) emission scenarios are evaluated.

67 Climate change

Response of Ocean Heat Content variability on Cyclone Frequency over North Indian Ocean QUICK ORAL Jiya Albert, Prasad K Bhaskaran OSICON2021/21 Department of Ocean Engineering and Naval Architecture, Indian Institute of Technology, India

The Ocean Heat Content (OHC) and its variability is a topic of immense interest having direct consequence on tropical cyclone activity over the North Indian Ocean region. The short- and long-term response of OHC requires a detailed study to better understand tropical cyclone characteristics. Recent decades have seen increased frequency of tropical cyclones in the North Indian Ocean (NIO) basin especially over the Arabian Sea (AS) that has a strong correlation with OHC variability. The current study provides a detailed evaluation of heat content (OHC300 , OHC700) using Ocean Reanalysis Data 5 (ORAS5) over the NIO basin, thereby determining the increased frequency of cyclones that formed over AS and Bay of Bengal (BoB) during the past four decades (1979–2020). Findings from the study signify an increase of 16.75% in the intensiﬁed storms (wind speed maxima exceeding 48 knots or 89 km/h) during the past four decades over the NIO. In addition, both AS and BoB basins exhibited a sequential decrease and increase in the heat content (OHC300, OHC700) prior to and after the year 2000. Increased trend in AS warming was about 1.21 times higher compared to BoB basin during the study period. Increased heat storage in AS waters has a correlation with decreased Outward Longwave Radiation (OLR) during the past 20 years (0.00175 W/m2). On the contrary, there is a signiﬁcant decreasing trend in OLR values over BoB for the same time period (+0.1079 W/m 2). These relationships can be utilized to understand the frequency of tropical cyclone characteristics over both BoB and AS basins. Further, the study also investigated the projections of OHC to understand characteristics of intense cyclones over AS in the future.

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Studies on tropical zooplankton and climate change, west coast of India ORAL OSICON2021/24 Kadam Surendra S1, Samal Deepika V2 1N.B.Mehta Science College, Bordi , Palghar 2Sonopant Dandekar college, Palghar, Maharashtra

Aquatic biodiversity has vast economic value and is mainly responsible for sustaining and supporting overall ecological health. Humans have long depended on marine resources for food, medicine and material as well as for recreational and commercial purpose such as fishing and tourism. plankton symbolize life in the water column which control the basic energy source at lower trophic levels and hence form an integral issue the world is currently facing. Climate change and global warming are potential threats to humanity. The effects of global warming on zooplankton are reflected as movements of the pole wing in the distribution of species and individual clusters, the early timing of important life cycle events or phenology, and changes in abundance and societal structure. The importance of zooplankton in ocean ecosystems and traits that make them climate change-sensitive beacons. Global warming may have greater implications for marine ecosystems than on terrestrial ecosystems, as temperature affects the stability of water poles, nutrient enrichment, new production, and thus the abundance, composition, size, diversity and nutritional efficiency of zooplankton. The relevant descriptions of physical changes in the oceans in response to climate change are presented as a prelude to a detailed discussion of the perceived effects of global warming on zooplankton. Zooplankton is an important part of the pelagic community since it includes the major consumers of primary production. The present study carried out from west coast showed zooplankton biomass ranging between 19.13 and 87.28ml/100m giving an average of 40.08ml/100m.In most of the creek system the zooplankton population showed wide fluctuation in high saline water and low saline condition, however in west coast maximum zooplankton population was observed in post monsoon period (Novem- ber to January). Zooplankton form an important link in the marine food chain as secondary producers. The present research work constitutes the ecological study of plankton from west coast of India.

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Genesis and trends in marine heatwaves over the tropical Indian Ocean and their interaction with the Indian summer monsoon QUICK ORAL J. S. Saranya1,2, M. K. Roxy1, Panini Dasgupta1,3, Ajay Anand1,4 OSICON2021/51 1 Centre for Climate Change Research, Indian Institute of Tropical Meteorology, Pune 2 College of Climate Change and Environmental Sciences, Kerala Agricultural University, Kerala 3 Department of Meteorology and Oceanography, College of Science and Technology, Andhra University, Visakhapatnam 4Department of Atmospheric Sciences, Cochin University of Science and Technology, Kerala

Marine heatwaves (MHWs) are extreme oceanic warm water events (above 90th 2 percentile threshold) that significantly impact the marine environment. Several studies have recently explored the genesis and impacts of MHWs though they are least understood in the tropical Indian Ocean. Here we investigate the genesis and trend of MHWs in the Indian Ocean during 1982–2018 and their role in modulating the Indian monsoon. We find that the rapid warming in the Indian Ocean plays a critical role in increasing the number of MHWs. Meanwhile, the El Niñohas a prominent influence on the occurrence of MHWs during the summer monsoon. The Indian Ocean warming and the El Niñovariability have synergistically resulted in some of the strongest and long-lasting MHWs in the Indian Ocean. The western Indian Ocean (WIO) region experienced the largest increase in MHWs at a rate of 1.2–1.5 events per decade, followed by the north Bay of Bengal at a rate of 0.4–0.5 events per decade. Locally, the MHWs are induced by increased solar radiation, relaxation of winds, and reduced evaporative cooling. In the western Indian Ocean, the decreased winds further restrict the heat transport by ocean currents from the near-equatorial regions towards the north. Our analysis indicates that the MHWs in the western Indian Ocean and the north Bay of Bengal lead to a reduction in monsoon rainfall over the central Indian subcontinent. On the other hand, there is an enhancement of monsoon rainfall over southwest India due to the MHWs in the Bay of Bengal.

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Relationship between Azores High and Indian summer monsoon ORAL OSICON2021/58 Ramesh Kumar Yadav Indian Institute of Tropical Meteorology, Pashan, Pune

South Polar Skua (Stercorarius maccormicki) is breeding endemic mostly to periph- eral Antarctica. Schirmacher Oasis (SO) is a snow free area in East Antarctica having 34 sq. km. area was selected by South Polar Skua (SPS), was study area. By point count method using ‘MAITRI’ station of India as reference point 11 active nests of SPS were identified. The nest survey for the SPS breeding activity monitoring was conducted by walk in the study area. Harsh weather conditions and very rough rocky terrain with scrap stones, boulders, low valleys and hills of SO during austral summer of Nov. 2019 to March 2020. The nest site selection was same but the nesting was well defined sequential activity. It is first record to locate exact nest sites of SPS 11 breeding pairs with data on lat. long. coordinates in SO. Land Locked Lakes (LLL) was selected for nesting by SPS instead of Pro-glacial lakes (PGL) and Epi-shelf lakes (EPL). The clutch size was 2-3 eggs/nest. The average value of breeding indices noted includes hatching success (65.2%), brood reared to advanced chick stage (13.13%) by regular and sincere feeding efforts by both the parents. The contribution of male SPS in all the nests for foraging trips was >70% compared to the efforts by female SPS. Both the parents were involved to demonstrate the feeding process using regurgitated food at nest site. Average time for foraging trips was recorded. The dominance of early hatched chick on late hatched was found, that result into forced escape of later in to 50-100 ft. away from nest area was found. Escaped chick was used as reserved food and hence maintained live to cannibalize at any required time of food need. The reasons for the 0.0% breeding success was due to 100% self cannibalism by their own parents are discussed.

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Footprints of Southern Annular Mode on The Indian Ocean Waves QUICK ORAL Meenakshi Sreejith OSICON2021/61 Indian National Centre for Ocean Information Services, Hyderabad

The annular modes are hemispheric scale patterns of climate variability as part of internal atmospheric dynamics in the middle latitudes. On riveting our attention to Indian Ocean, the potential imprints of tropical-extra tropical teleconnection of Southern Annular Mode (SAM) through sequential changes of Hadley cell on the North Indian Ocean (NIO) wave parameters are investigated in the present study. Marshall SAMI values are taken for the present study which was carried out from December 1979 to February 2018. The positive (negative) phase of the SAM occurs when the pressure anomaly is low (high) on the pole, and the mid-latitude westerly jet is shifted poleward (equatorward). ERA5(ECMWF ReAnalysis) model data were used for analysing the variables under study, covered from january 1979 to within 5 days of real time. It is the fifth generation atmospheric reanalysis from ECMWF, ERA5–hourly data at 31km horizontal resolution with 137 levels up to 0.01 hPa. The composite analysis of Significant wave height( SWH), Swell wave height (SHTS), mean wave period (MWP), and wind sea height (SHWW ) anomalies for SAM positive and negative years reveal that JJA (June, July and August) season is most susceptible to other seasons. SWH, SHTS, MWP, and SHWW fields are stark opposites during the positive and negative phases of SAM and band-wise in the different IO regions. The southwest monsoon and the strengthening of SAM during the negative phase contribute to IO’s highest mean wind fields during JJA. Wind speed is maximum (10m/s–14m/s) between 40◦S-60◦S. The dominance of wind seas during this period is visible from the lowest MWP fields of JJA. The swell fields are also indicative of this, with the highest swells during JJA. The signature of SAM is evident in the atmospheric signals linked to the change in wave parameters due to the altering wind as a result of modified Hadley cell over this region. A positive(negative) SAM event corresponds to a widespread (constricted) downdraft and intense (less severe) updraft of Hadley cell. These changes are a direct consequence of the poleward and equatorward shift of wind during SAM phases. The study establishes the relevance of SAM as a persuasive factor towards wave climate and the covarying atmospheric counterparts in the IO.

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The physiological response of Scylla serrata under the inﬂuence of climate change related factors and oil pollution QUICK ORAL Sritama Baag, Sumit Mandal OSICON2021/78 Marine Ecology Laboratory, Department of Life Sciences, Presidency University,Kolkata

Ever since the industrial revolution, marine ecosystems are encountering numerous environmental challenges and myriad anthropogenic perturbations. Based on cur- o rent trends of intense atmospheric CO2 emission, an escalation of 2–4 C average surface water temperature alongside diminution by up to 0.4 pH units is predicted by the year 2100. In recent years, petroleum products transportation and its usage have increased in manifold which causes accidental oil spill. From the past few decades, the Sundarban estuarine system is underneath threat due to natural and anthropogenic disturbances. The mud crab (Scylla serrata) is one of the most commercially exploited species for aquaculture in Sundarbans. The key objective of this study was to decode whether rearing under global environmental drivers (ocean warming and acidification) exacerbates effect of local diver (oil pollution) on physiological responses of S. serrata. Animals were reared separately for 30 days under two scenarios: a) current climatic scenario (pH 8.1, 28oC) and b) predicted climate change scenario for 2100 (pH 7.7, 34oC). After this duration half animals of each treatment were exposed to 5mgL−1 of marine diesel oil (MDO) for 24hours and the other half remained uncontaminated. This resulted in 4 different treatments: a) pH 8.1 and 28oC in the absence of MDO; b) pH 8.1 and 28oC with MDO; c) lower pH 7.7 and elevated temperature 34oC in the absence of MDO and d) pH 7.7 and 34oC with MDO. Physiological energetics like ingestion, egestion, respiration and excretion rates were evaluated. Ingestion rate reduced, whereas egestion rate was higher in treatments compared to control. Respiration (except pH 8.1 and 28oC with MDO) and ammonia excretion rate increased in stressful treatments with respect to control. Stressful conditions appear to negatively impact crabs by elevating metabolic rates. This might have led to reductions of energetically expensive processes like feeding and digestion. Thus, the amount of energy available for growth declines and the ecological efficiencies are reduced considerably. The present results clearly highlighted the detrimental combined effect of climate change mediated stressors and pollution on physiological energetics of crab that might potentially reduce its population and affect the coastal aquaculture in forthcoming years.

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Modeling the drivers of the spatiotemporal variability of the surface pCO2 in the Bay of Bengal QUICK ORAL A. P. Joshi, V. Kumar, H. V. Warrior OSICON2021/82 Department of Ocean Engineering and Naval Architecture, IIT Kharagpur

The Bay of Bengal is one of the most challenging zones to model carbon dioxide (CO2 ) dynamics on account of higher freshwater inﬂux and less data available. In this study, we use a coupled physical-biogeochemical (ROMS-PISCES) model to investigate the drivers responsible for the spatiotemporal variability of the surface partial pressure of carbon dioxide (pCO2 ) in the Bay of Bengal region. The seawater pCO2 is known to be a function of the concentration of dissolved inorganic carbon (DIC), total alkalinity (TALK), sea surface temperature (SST), and sea surface salinity (SSS). To understand the contribution of each of these drivers, we decompose the pCO2 into the four components using the Taylor series expansion and then ignoring the higher-order terms. Then a series of simulations are run using the CO2SYS model by providing a small perturbation to each of these drivers individually. The

SST, DIC, and SSS are the primary drivers of the sea-surface pCO2 anomalies, while TALK has minimal effect. The effect of SST and DIC is observed to be opposing in nature. The SSS is found to have maximum effect in the post- monsoon season and minimum in the winter monsoon season. The SSS has a reasonable contribution in the pre-monsoon season as well. The annual mean spatial observation shows that the DIC and TALK have an opposing nature, while SST and SSS balance each other.

The northern Bay of Bengal is observed to have negative pCO2 anomalies, primarily due to the freshwater inﬂux from rivers and precipitation.

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Ocean warming over the past three decades: Implications on Arctic methane emissions caused by hydrate dissociation QUICK ORAL Akash Trivedi, Sudipta Sarkar OSICON2021/84 Department of Earth and Climate Science, Indian Institute of Science Education and Research, Pune

The effect of ocean warming is becoming more evident in the Arctic, such as the retreat of ice sheets and accelerated glacier melting. There is a concern about the stability of methane hydrate deposits in marine Arctic sediments. The marine sediments at the Fram Strait, the Arctic-Atlantic gateway located in the western Svalbard region, host methane hydrates. A marine geophysical expedition in 2008 discovered plumes of methane bubbles emanating from the seafloor close to and further upslope of the present-day methane hydrate stability on the eastern margin of the Fram Strait. Past CTD records on the upper continental slope show the bottom water temperature of the northward-flowing West Spitsbergen current increased by 1oC over the last thirty years. The warming trend is alarming because it can destabilize the hydrate. Most importantly, the seasonal temperature fluctuations of the bottom water are also a critical aspect to be considered for repeated hydrate formation and melting. We conducted numerical modeling to ascertain the behaviour of methane hydrate in response to decadal scale bottom water temperature variations along with the seasonal fluctuations in temperature over 111 cal years BP. We demonstrate repeated episodes of hydrate dissociation and reformation at a shallower depth. The permeability governs the methane flow; therefore, we tested both high (10−13) and low permeability (10−17) models. Our results provide robust evidence that the region’s methane flare activity is reduced during winter when the bottom-water temperatures are substantially lower than in summer. The modeling enhances our understanding of the behaviour of methane hydrate and helps to visualize realistic scenarios of methane emission in the marine Arctic.

75 Climate change

Denitriﬁcation record from Eastern Arabian Sea indicating South Asian Monsoon Variability during late Pliocene QUICK ORAL Padmasini Behera, Manish Tiwari OSICON2021/97 National Centre for Polar and Ocean Research (NCPOR), Ministry of Earth Sciences, Goa

The South Asian Monsoon (SoAM) is one of the extreme climatic events, but its variability during warmer periods is not established yet. Understanding the response of SoAM to the warming conditions could help in predicting the future SoAM variability in the current global warming scenario. The Mid-Pliocene warm period (MPWP, 3.264 to 3.025 Ma) is the most recent such event when the Earth’s boundary conditions were similar to present with similar CO2 concentration (more than 400 ppmv) and temperature (2-3oC higher than present). It acts as the best analogue for understanding the impacts of future global warming on SoAM. The high-resolution record of denitrification from the Eastern Arabian Sea can provide an insight into the strength of Monsoon variability during MPWP. Denitrification is the process by which nitrate is reduced to nitrogen gas (N2 or N2O) during organic matter decay in OMZs in the water column. The denitrification process enriches the nitrate pool with 15N, which is reflected in the particulate organic matter. It governed by the surface water productivity and the water column ventilation, where the productivity is related to monsoonal upwelling. We analyzed the nitrogen isotopic ratio of sedi- 15 mentary organic matter (SOM, δ NSOM ) to examine denitrification in the Eastern Arabian Sea. Total nitrogen (TN%) and total organic carbon (TOC%) are used to determine the surface water productivity from the sediment collected during expedition IODP 355, Hole U1456A. We find that during warmer periods of MPWP, the high δ15N values correspond to the high productivity as shown by both TN and TOC. The stronger denitrification and high productivity indicate the intensification of SoAM during warmer periods of the Late Pliocene including MPWP. Enhanced denitrification during this period could be due to the monsoon driven upsurge in productivity and reduction in deep water ventilation.

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Regional Modeling of Extreme Temperature Trends over India QUICK ORAL Nishtha Agrawal ,Vivek Kumar Pandey OSICON2021/101 K Banerjee Centre of Atmospheric and Ocean Studies, Institute of Interdisciplinary Studies (IIDS), University of Allahabad, Prayagraj

The studies carried out by various organizations have unequivocally reported an increasing trend in mean global climate which has led to an increased number of extreme weather events over major parts of the globe. Since India is predominantly agriculture dominated country, the prediction and understanding of likelihood of these events become essential for the economic growth of this country. The present study intends to infer about the monotonic trends in TT on the seasonal basis; here we quantiﬁed the extent of temperature extremes corresponding to winters, sum- mers, monsoon and post monsoon seasons in India using diﬀerent statistical measures. We have performed our analysis using the Regional Climate Model (RegCM v4.6) outputs covering 24 years of study (1982-226). Our analysis reveals the cooling (warming) of lower (upper) troposphere for almost all the seasons in our study which can be directly linked to the change in latent and radiative heating of the atmosphere. These changes in TT characteristics can be useful in analyzing the extreme weather conditions and abrupt rainfall patterns seasonally and annually.

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Bi-decadal variation of saltwater vulnerability in coastal district of Raigad, Maharashtra, India. QUICK ORAL Barnali Das, Anargha Dhorde OSICON2021/119 Department of Geography, Nowrosjee Wadia College,

Low lying coastal areas are one of the most populated regions of the world. Various activities like agriculture, tourism, industries and allied activities thrive and grow in this region. Such coastal areas are often under stress of sea water intrusion due to various natural and anthropogenic reasons. Raigad, a coastal district located on west side of Maharashtra, India, with a coastline of 110 km in length is observed to be susceptible to the problem of salt water intrusion. Climate change and increasing anthropogenic pressure is creating stress for ground water resources. Over extraction of ground water is leading to saltwater intrusion into coastal aquifers. Seawater ingression has many negative impacts over the region and temporally it has been observed that the extent of intrusion is increasing day by day creating threat to the society. In the present study an attempt has been made to analyze bi-decadal scenario of saltwater intrusion vulnerability with the help of model GALDIT. It is an indicator based model that depends on hydrogeological parameters of a region. There are six parameters in GALDIT namely Groundwater occurrence (aquifer type: unconfined, confined and leaky confined), Aquifer hydraulic conductivity, Level of groundwater above sea level, Distance from the shore (distance inland perpendicular from shoreline), Impact of existing status of seawater intrusion in the area and Thickness of the aquifer which is being mapped. GALDIT vulnerability scores depend on three important parts- weights, ratings and ranges. This model can be modified with respect to weights. High weight can be allotted to any parameter depending up on hydro geological setting of a region. GALDIT scores have been calculated for the year 2000 and 2019 over Raigad district. 140 wells have been analyzed for saltwater ingression. It has been observed that GALDIT scores have increased from moderate vulnerable to highly vulnerable. The results reveals that salinity has increased in the area specifically over Shivardhan, Murud, Alibag and Uran. Increased mangroves in these talukas are an indication to rise in salinity.

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The decadal sea level variability observed in the Indian Ocean tide gauge records and its association with global climate modes ORAL OSICON2021/159 J.S. Deepa, C. Gnanaseelan Indian Institute of Tropical Meteorology, Pune

The understanding of sea level variability and trends in the Indian Ocean is essential in the context of its important social, economic and environmental impacts on the rim countries and low-lying islands. The coastal sea level changes occurred during the past century is identified from the tide gauge sea level measurements, which indicate rising sea levels at most of the Indian Ocean coastal stations. The Indian Ocean sea level exhibits large decadal variability also, superimposed on these increasing sea level trends. The decadal sea level variability of the Indian Ocean is studied using long-term tide gauge observations. The present study reveals the existence of close association between Indian Ocean sea level and the global decadal climate modes, such as Pacific Decadal Oscillation (PDO) and/or Atlantic Multi- decadal Oscillation (AMO) at most of the tide gauge stations. An anti-phase sea level evolution with PDO index is identified in the regions such as west coast of India, east coast of India and the western coast of Australia. Moreover, the PDO related sea level variability is found to be stronger at the tide gauge stations along the west coast of India compared to that along the east coast of India. On the other hand, the tide gauge station at Mumbai with more than 100 years of data shows an in-phase relationship with AMO index on the decadal timescales. The analysis of sea level pressure (SLP), rainfall and winds over the tropical Indian Ocean indicates existence of strong relationship with AMO especially over the Arabian Sea region, strongly suggesting that the variability observed at the tide gauge station Mumbai may have larger spatial signatures. During the positive phase of AMO, the Arabian Sea region is characterized by large fall in SLP and a strong cross equatorial flow towards the Indian land mass, which are primarily responsible for the positive sea level anomalies (SLAs) at the Mumbai tide gauge station and the adjacent regions.

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India’s Mission of a ‘Clean and Green Navy’ QUICK ORAL Arjun OSICON2021/160 Jindal School of International aﬀairs, O.P. Jindal Global University, Sonipat, Haryana

The Indian Navy as a maritime service institution has been presented with the responsibility to help achieve both military and politico-diplomatic objectives. In conjunction with its traditional mandate of safeguarding the country’s sovereign territorial waters from foreign aggressors, the Navy has been additionally tasked, to engage in soft power diplomacy. Successfully straddling both hard and soft powers with equal eﬃcacy, the Indian Navy has imbued a new sustainable approach in its organisational structure. In view of this, the Navy has drafted and recently adopted the ‘Indian Navy Environment Conservation Roadmap’ (INECR), a blueprint of policies to ensure the alleviation of energy consumption, while striving to create ‘Blue Water Operations with a Green Footprint’. In the pursuit to mitigate carbon footprints and to promote a sustainable ‘Clean and Green Navy’, the maritime institution has authorised and set into motion several new measures such as ‘No Vehicle Days’ and ‘Vehicle Free Base’ including the implementation of the International Con- vention for the Prevention of Pollution from Ships (MARPOL) regulations, among many other initiatives across all Naval establishments. In cognisance of this new sustainable endeavour, this study is set to unravel and comprehend the various initiatives and policies under the INECR that seek to control the carbon emissions. This research shall be conducted by relying on the parent document of the INECR in conjunction with other oﬃcial Government reports and scholarly articles

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Primary Productivity and Bio-optical Variability in the Indian Sector of the Southern Ocean: Observations from Austral Summer 2015 QUICK ORAL Anvita U. Kerkar1, S. C. Tripathy1, P. Minu2, N. Baranval3, P. Sabu1, S. Patra4, OSICON2021/164 R. K. Mishra1, A. Sarkar1,5 1National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Vasco-da-Gama, Goa; 2Central Institute of Fisheries Technology, ICAR, Willingdon Island, Kochi; 3National Remote Sensing Centre, ISRO, Balanagar, Hyderabad; 4National Centre for Coastal Research, Ministry of Earth Sciences, NIOT Campus, Chennai; 5Environment and Life Sciences Research Centre, Kuwait Institute for Scientiﬁc Research Centre, Al-Jaheth Street, Shuwaikh, Kuwait

The Southern Ocean (SO), despite its well-known role in global primary productivity (PP), is left underexplored in this aspect. The ambient light field is crucial to understand and elucidate PP and the processes associated. The present study constitutes a dual effort to address PP and the bio-optical variability in the Indian Sector of the Southern Ocean (ISSO). Highest estimates of PP suggest the Sub- Tropical Front (STF) to be the most productive front, while Polar Front-2 (PF2) to be the least. Subsurface PP maxima at most of the stations imply probable photoinhibition or micronutrient limitation at the surface layer. Well correlated estimates from measured and satellite-based integrated PP (R2 = 0.94, RMSE = 77.48, p < 0.01) suggest the applicability of using global models in their original formulation despite the optically complex nature of the SO waters. The photochemical efficiency of phytoplankton (Fv/Fm) varying between 0.1 - 0.4, highlights the low to moderate photosynthetic efficiency of the ISSO phytoplankton. A clear dominance of small-sized phytoplankton at the surface and larger ones at the subsurface layers could be detected through the ratio between remote sensing reflectance (Rrs)-derived phytoplankton absorption (aph) at blue-red band (B/R ratio). The differences in ∗ Chl-a specific phytoplankton absorption (a ph) and phytoplankton absorption (aph) indicated photo-adapted state of the underlying phytoplankton community to the ambient (low) light conditions, evidenced through the efficient light harvest yield in the region. Whereas, lesser contribution of aph revealed a significant influence of non-phytoplankton materials to the total absorption budget. We hence For Award infer that the phytoplankton community and productivity were more critically mod- ulated by the physicochemical settings in the surface compared to the subsurface waters of the ISSO.

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Frequency of monsoon depression over the Indian seas and landmass during onset, withdrawal, and mainmonsoon season and the associated rainfall variability QUICK ORAL Sanjukta Rani Padhi and Pratap Kumar Mohanty OSICON2021/180 Department of Marine Sciences, Berhampur University, Berhampur, Odisha

Monsoon Depressions (MDs) are synoptic-scale phenomena that originate over the Bay of Bengal (BOB), Arabian Sea (AS), and Indian landmass. MDs have a signif- cant effect on monsoon precipitation. This study examined all the monsoon depressions that originated over the Indian seas and landmass for the period 1901-2018 and the rainfall variability over All India and different homogeneous zones during onset (June), main monsoon(July-August), withdrawal(September), and the whole monsoon season(JJAS). The trend of MDs analyzed through the 11-year running mean indicates an increasing trend during the onset phase (June) while decreasing trends are observed for other phases of the monsoon. Decadal variability of MDs separately over the Arabian Sea, Bay of Bengal, Indian Landmass and all together, frequency of MDs in the excess, deficit and normal years, and genesis positions of MDs are studied during the four different phases of monsoon. The correlation coefficient between the number of MDs and rainfall of different homogeneous zones of India during different phases of monsoon are examined for the period 1901-2018, 1901-1950 (past cooling period) and 1951- 2018 (current warming period). The study reveals distinct levels of statistical significance at different phases of the monsoon and in different data periods. The results show distinct declining trend in MDs during withdrawal period, higher frequencies of MDs during excess years as compared to deficit and normal years in all the phases of the monsoon except withdrawal phase. Mean and standard deviation of rainfall during different phases of the monsoon for the whole period (1901-2018), for the years without MDs, and for the years with MDs show significant variability. The mean frequency of MDs during the past cooling period (1901-1950) is highest followed by a long period (1901-2018) and the current warming period (1951-2018) and shows different levels of statistical significance. The results reveal a positive decadal trend during the past cooling period while negative decadal trends are observed during the current warming period and long period data.

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Combined Inﬂuence of ENSO and IOD on the strength of Northeast Monsoon Rainfall over the peninsular India QUICK ORAL E.K. Simon1, R. Sajeev1, Basil Mathew2 OSICON2021/226 1Dept. of Physical Oceanography, Cochin University of Science & Technology, Cochin; 2Kerala University of Fisheries and Ocean studies (KUFOS), Cochin

The peninsular India consisting of the India meteorological subdivisions viz., coastal Andhra Pradesh, Rayalseema, south interior Karnataka, coastal Karnataka, Tamil Nadu, and Kerala receives about 29.3% of its annual rainfall during the Northeast East Monsoon (NEM) season. Northeast monsoon is very critical for southeast peninsular India, especially Tamilnadu and is very important for the drinking water and agricultural activities of this region. Northeast Monsoon of peninsular India is categorised as strong, weak and normal depending on the strength of Northeast Monsoon Rainfall (NEMR) in comparison to the long period average. Using composite analysis, variability of NEMR is studied during the El-Nino and La-Nina years during the period 1950 to 2016 and the results show that El-Nino years rainfall mean is more than the long period average (LPA) and La-Nina years rainfall mean is less than the LPA indicating that El-Nino strengthens NEMR whereas La-Nina weakens it. The strength of NEMR is also analysed during the positive and negative phases of I OD years using composite analysis during the period 1960 to 2016 and the results show that the positive IOD years rainfall mean is more than the LPA and the negative IOD years rainfall mean is less than LPA indicating that positive IOD conditions strengthen NEMR whereas negative IOD conditions weaken NEMR. The combined inﬂuence of ENSO and IOD on NEMR strength is also investigated.

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Demonstrating the potential of Regional Ocean Model System (ROMS) in simulating the upper ocean characteristic over Arabian Sea: impact of horizontal resolution QUICK ORAL Prabha Kushwaha OSICON2021/231 K. Banerjee Centre of Atmospheric and Ocean Studies, Institute of Interdisciplinary Studies, Nehru Science Centre, University of Allahabad, Prayagraj- 211002, India

This study attempted to demonstrate the skill of the regional ocean model system (ROMS) is simulating the hydrographic property of the Arabian Sea (AS). Addi- tionally, the impact of horizontal resolution is investigated. In this regard, ROMS is integrated over AS covering [30E-80E; 5N-30N] at two diﬀerent horizontal resolutions 1/6o(∼17km) and 1/4o(∼25km) for ten years. The comparison of model results with available observation and reanalysis indicates reasonable resemblances in reproducing the spatial-temporal distribution of surface and subsurface hydrographic property i.e. sea surface temperature (SST), sea surface salinity (SSS), sea surface currents, and subsurface temperature and salinity at both resolutions. The increasing resolution shows minimal improvement, indicating the fact that its not always guaranty to enhance the performance towards increasing resolution for every aspect.

84 Climate change

West Paciﬁc subtropical high, typhoon activity over northwest Paciﬁc and linkage with Indian summer monsoon rainfall QUICK ORAL Roja Chaluvadi1,2, Hamza Varikoden1, Milind Mujumdar1, S. T. Ingle2 OSICON2021/233 1Indian Institute of Tropical Meteorology, Pashan, Pune-411008, India; 2Kavayitri Bahinabai Chaudhari North Maharashtra University, Jalgaon-425001, India

In the present study we have examined the variability in zonal displacement of western edge of west Pacific subtropical high (WPSH) location and northwest Pacific (NWP) typhoon activity and their association with Indian summer monsoon rainfall (ISMR) during the peak summer monsoon season (July-August) from 1945 to 2019. The variability and inter-linkages of these parameters were analysed using the geopotential height, surface winds and specific humidity datasets from NCEP/NCAR reanalysis with 2.5 x 2.5 degree latitude- longitude spatial resolution. Typhoon tracks, frequency and density over the NWP were collected from the Joint typhoon warning center (JTWC). Daily rainfall data is used from APHRODITE. The interannual variability in zonal displacement of western flank of WPSH (location index) is calculated by using eddy geopotential height which is obtained by removing the zonal mean of geopotential from mean geopotential height. Based on the relationship between location index and variability in departures of TCs count, the total study period is classified as four phases. Those are termed as 1st quadrant (eastward shift of western flank along with more number of TCs), 2nd quadrant (eastward shift of western flank along with less number of TCs), 3rd quadrant (westward shift of western flank along with less number of TCs) and 4th quadrant (westward shift of western flank along with more number of TCs). The WPSH attains more (less) strength when there is more (less) number of typhoon activity during peak monsoon season. The westward (eastward) shift in western edge of WPSH along with less (more) number of typhoon activity over the NWP is associated with surplus (deficit) rainfall over the Indian subcontinent during peak season.

85 Climate change

Long-term changes in monsoon winds in response to ocean warming QUICK ORAL Parvathy Anil1,2, M. K. Roxy1 OSICON2021/250 1Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune; 2Department of Atmospheric Sciences, Cochin University of Science and Technology, Kerala

More than 80% of the rural population in India is dependent on the agricultural sector of the country, which is largely rain-fed. 78% of the country’s annual rainfall is obtained from the South-west Monsoon during June-September, known as the Indian Summer Monsoon (ISM). It is hence important to study the changes in the southwest monsoon winds that transport the moisture from the Indian Ocean to the subcontinent.

A study of the long-term variability of winds using 30 years (1980-2010) of data from the European Centre for Medium-Range Weather Forecasts (ECMWF) shows an increasing trend in the equatorial region and south-west trade winds. However, a signiﬁcant decreasing trend is observed along the northern part of the Indian peninsula, associated with a local weakening of the monsoon. The strengthening of the westerly enhances the wind speed and transports more moisture to the northern Indian Ocean. However, the weakening of the winds over the Indian subcontinent could mean that the moisture is not transported inland, potentially impacting the monsoon rainfall.

These regional trends in the monsoon winds are captured by the third mode of Empirical Orthogonal Function Analysis (EOF), representing 10.8% of the total variability. The third EOF mode is in turn correlated with large-scale ocean warming, indicating that the long-term variability of the mean wind speed trend for the period from 1980-2020 for the Indian Summer Monsoon months (JJAS) is associated with global ocean warming signal.

86 Climate change

CMIP5 and CMIP6 ﬁdelity in representing the IPOC mode characteristics and its link with the Indian summer monsoon rainfall ORAL OSICON2021/262 Darshana D Patekar1,2, Jasti S Chowdary1, C. Gnanaseelan1 and Anant Parekh1 1Indian Institute of Tropical Meteorology, Pune; 2Savitribai Phule Pune University, Pune

The inter-basin feedback processes over the tropical Indian ocean (TIO) and tropical western North Pacific (WNP) during the post-El Niñosummer form the coupled mode known as the Indo-western Pacific Ocean capacitor (IPOC) mode. Performance of 22 fifth and 23 sixth historical simulations of Coupled Model In- tercomparison Project (CMIP5 and CMIP6) models are evaluated with their first ensemble member during 1901-2005 and 1901-2014 respectively from interannual to interdecadal timescale. IPOC index is referred as the leading principal component of singular value decomposition (SVD) method applied to TIO sea surface temperature (SST) and tropical WNP 850-hPa relative vorticity anomalies in summer (June-July-August; JJA) that gives maximum covariance between them. Observa- tional analysis display positive phase of IPOC mode as anomalous WNP anticyclone (WNPAC) and TIO SST warming. IPOC induced southwest-northeast (positive- negative) dipole rainfall pattern is noted over the Indian summer monsoon (ISM) region on interannual timescale. Many models from both the phases show good skill in capturing the IPOC features and IPOC-ISM teleconnections. Multimodel mean (MMM) of these models reveal better representation of IPOC characteristics than individual models. For the same subset of good models, the interdecadal variability of IPOC mode is investigated by calculating the 21-year sliding window correlation of JJA IPOC index and ISM dipole precipitation index. On the basis of this, high correlation epoch (EP-S) and low correlation epoch (EP-W) are prepared that emphasizes epochal analysis ofIPOC system. IPOC mode components and positive (negative) rainfall over southern peninsular India (southern part of central-northeast homogeneous region) are well simulated in EP-S in both CMIP models including some discrepancies. During EP-W, majority of the models depict overestimated ENSO signals, modified WNPAC structures and weak SST cooling in southeastern TIO which creates unfavourable condition for IPOC mode development and resulted into weak IPOC-ISM rainfall relationship. The key cause behind modified IPOC mode is found to be unusual long persistence of robust SST anomalies and their meridional asymmetric nature over tropical central-eastern equatorial Pacific ocean in summertime. This is mainly due to simulation of ENSO decay pace that creates large inter-model spread in CMIP5 and CMIP6 models.

87 Climate change

Beneﬁts of satellite XCO2 and newly proposed atmospheric CO2 observation network over India in constraining Indian Ocean prior ﬂuxes QUICK ORAL Santanu Halder1,2, Yogesh K. Tiwari1,2, Vinu Valsala1,2 OSICON2021/284 1Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune, India; 2Department of Atmospheric and Space Sciences, Savitribai Phule Pune University, Pune, India

Ocean is one of the key reservoirs to store carbon. About one-fourth of the atmospheric CO2 (emitted by anthropogenic activity) is absorbed by the Ocean. But the Ocean fluxes are poorly known through processed-based study (i.e. Bottom-Up approach) in the carbon cycle. The observations over the ocean are also limited. Top-down modeling estimates are among the most reliable information about carbon fluxes due to terrestrial biosphere, oceans, and fossil fuels. In this study, we investigated the effect of ground- based observations, 17 new stations over India, and satellite XCO2 observations to reduce the uncertainty of prior flux of the In- dian Ocean using TransCom cyclo-stationary inversion implemented for 22 and 28 regions. The satellite XCO2 observation alone is able to reduce the sea-to-air flux uncertainty by ∼10% while we may achieve a maximum 30% uncertainty reduction using a combination of satellite observations of XCO2, surface observations of CO2 from existing global stations, and from proposed 17 new stations over India. We can obtain ∼25% uncertainty reduction using surface observation and 17 new stations over India for the case of the Arabian Sea.

88 Climate change

Assessment of climate variability in coastal wetlands of Pichavaram mangroves through satellite images QUICK ORAL T. German Amali Jacintha1,2, Radhika Rajasree. S.R2,3, J. Sriganesh4 OSICON2021/292 1Centre for Remote Sensing and Geoinformatics, Sathyabama Institute of Science and Technology, Chennai; 2Centre for Ocean Research, Sathyabama Institute of Science & Technology, Chennai; 3Faculty of Fisheries, Kerala University of Fisheries and Ocean Studies, Cochin; 4Department of Ocean Engineering, Indian Institute of Technology Madras, Chennai

Ecosystem sustainable management and development from different frequency of natural (climatic change, cyclone, tsunami, and hydrodynamic, etc) and anthropogenic (deforestation, pollution, and human encroachment by reclamation, etc) hazards requires essential awareness for a longer period spatio-temporal discrepancy. The present study envisages for the identification of the changes and assessments of the enlargement, contraction and distributions of Pichavaram Mangrove Forest with respect to the climatic changes. The Pichavaram mangrove wetland is located (latitude 11o 25’ 32” N and longitude 79o 47’ 49”E) in the northern extreme of the Cauvery delta, near the mouth of River Coleroon at Cuddalore district of Tamil Nadu state with a total area of about 1,350 hector. The climatic change impacts on the spatial extent for a period of thirty (30) years from 1991 to 2021 were identified using multispectral satellite images from Landsat TM (30m resolution) to Sentinel 2 (10m resolution). The Normalized Difference Vegetation Index (NDVI) mapping tool used for the satellite image classification technique for the identification of the mangrove area and non-mangrove areas. The spatial demarcations of the mangrove vegetations of 2021 satellite image classifications confirmed by the selected train- ing/representative Pichavaram Mangrove Forest sites by the field surveys carried with the help of Global Positioning System (GPS) with the accuracy of less than a meter. The ecosystem (mangrove forest) changes were compared with the climate variables of temperature, precipitation, temperature-seasonality, as well as historical sea-level data collected from the secondary sources (literatures, met-oceans, etc). These satellite image analysis assessments confirm the significant changes on mangrove ecosystems spatial distributions due to the resemblance with the decade, biannual and annual climate changes along with the anthropogenic activities and also with the apparent natural calamity devastation.

89 Climate change

Intraseasonal oscillation of boreal monsoon rainfall and its coherence with meridional sea surface temperature gradient in the Bay of Bengal QUICK ORAL Reji M. J. K.1, Hamza Varikoden1, C. A. Babu2 OSICON2021/305 1Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune; 2Dept. of Atmospheric Sciences, Cochin University of Science and Technology, Cochin, Kerala

Indian summer monsoon is predominantly driven by the 30-60 day mode of Intrasea- sonal oscillation (ISO) via active break cycles. Indian Ocean plays a key role in the genesis and propagation of ISO, as the manifestation of active and break cycles. The inseption of the ISO originates in the equatorial Indian Ocean and migrates these convective cloud bands northward over the Bay of Bengal (BoB) . We developed an index named ’BoB Meridional SST Index (BMSI)’ which is based on the meridional temperature gradient between the east equatorial Indian Ocean (EEIO) and the northern BoB (NBB). The influence of BMSI on Indian Summer Monsoon Rainfall (ISMR) was analysed for the period from 1982 to 2019. The correlation analysis of BMSI and ISMR over central Indian region manifest a proceeding and receding phases with the correlation coefficient of 0.87 and 0.96, respectively. The HGD days (LGD days) were defined based on the +1 (-1)standard deviation of BMSI at least for three consecutive days. The SST over the NBB exhibits anomalous heating associated with cooling over the Bay of Bengal cold pool during the HGD and an anomalous cooling of the NBB during the LGD periods. The HGD and LGD are explicitly mimicking the active and break phases of ISMR.The acceleration of low level westerlies is clearly evident during the HGD days whereas the LGD days manifest significant weakening of low level westerlies. An anomalous convergence is apparent during the HGD days, whereas anomalous subsidence is dominated during the LGD days. Thus it can be concluded that the HGD (LGD) is associated with the active (break) monsoon period and thereby it governs the intraseasonal oscillation of ISMR.

90 Climate change

Analysis of the intensity and rate of tropical expansion QUICK ORAL Parvathy M1, Roxy Mathew Koll2 OSICON2021/306 1Department of Physical Oceanography, Cochin University of Science and Technology, Kochi; 2Indian Institute of Tropical Meteorology, Pune,

Earlier observational studies show a pole ward expansion of tropics and its link to anthropogenic greenhouse gas emissions. These studies on tropical expansion are mostly on the changes in atmospheric conditions. Long-term changes in atmospheric conditions are tightly linked to oceanic climate and it is hence important to explore the tropical expansion in oceans. This is particularly important since more than 93% of the additional heat from global warming has gone into the oceans. Here, in this study we analyse the long-term trends in the tropical belt and Hadley cell, and quantify this expansion using several metrics. Decreasing outgoing long wave radiation (OLR) trend over all ocean basins indicates increasing convection and thereby intensifying Hadley cell over all ocean basins. This is more over tropical north Indian Ocean due to the effects of rapid Ocean warming and ENSO. Tropical expansion is quantified using metrics based on stream function, zonal surface wind crossing, maximum sea level pressure, outgoing long wave radiation and changes in precipitation with respect to evaporation. All the metrics indicate a pole ward expansion of tropics- particularly, the metrics based on near surface zonal wind and precipitation/evaporation gives statistically significant results. Correlating this metrics with global sea surface temperature (SST) indicates that this tropical expansion is connected to oceanic climate variability and change, associated with the cold phase of El NiñoSouthern Oscillation (ENSO) and Pacific decadal oscillation (PDO) and particularly the Indo Pacific warm pool expansion. Accelerated expansion of Hadley cell circulation since 1980 is strongly associated with the areal expansion of Indo Pacific warm pool.

91 Climate change

Relationship between Global SST and Summer Monsoon Rainfall in Six Intensity Bins over Five Homogenous Regions in India QUICK ORAL Reshma T1, Hamza Varikoden2, C. A. Babu1 OSICON2021/316 1Department of Atmospheric Sciences, Cochin University of Science and Technology, Kochi ; 2Indian Institute of Tropical Meteorology, Ministry of Earth Sciences Pashan, Pune

Summer monsoon rainfall varies in intensity and spatial coverage over different parts of India. In this study, an attempt is made to investigate the influence of sea surface temperature of global oceans on the summer monsoon rainfall in different regions (SMR). The study is carried out utilising rainfall and SST data for a period of 1901- 2020 available from India Meteorological Department and Met Office Hadley Centre. On the basis of SMR, India is subdivided into five homogeneous regions, viz. Northeast India (NEI), Northcentral India (NCI), Northwest India (NWI), Westcentral India (WCI) and Peninsular India (PI). Further, the SMR is classified into six intensity bins based on percentile values, viz. dry, low, moderate, high, very high and extreme events for each region. Linear correlation analysis between SMR in different regions and global SST has been made to identify the dominant oceanic regimes with a substantial relationship. We identified eight regions in Indo-Pacific regimes, they are Arabian Sea, Bay of Bengal (BoB), South China Sea (SCS), South west Indian Ocean (SWIO), North Central Pacific Ocean (NCPO), Niño3, Niño3.4 and South west Pacific Ocean (SWPO). A 31-year sliding correlation analysis was carried out to determine consistency of rainfall - SST relationship for the identified regimes throughout the period for SMR and its intensity classes. Analysis brings out that SMR in all homogenous regions (NCI, NWI, WCI and PI) are significantly correlated with Niño 3, Niño3.4 regions, except NEI. Another interesting finding is that the rainfall-SST relationship has changed significantly in recent decades, in NEI the extreme intensity bin correlation has increased (decreased) with SST in Arabian Sea, BoB and SCS (NCPO); very high intensity bin in WCI and NWI and extreme bin in PI correlation have increased with NCPO SST; likewise relationship variations are shown by moderate and extreme bins in WCI and high and extreme bins in NCI with SCS SST. In NEI, NCI and NWI, SMR contribution to correlation is primarily made by high, very high and extreme intensity bins. Evidently to WCI and PI, rainfall intensity classes show variable contribution to the SMR - SST correlation.

92 Coastal and Open Ocean processes (COOP)

Sessions’ Chairman

Dr. Sanil Kumar National Institute of Oceanography (NIO), Goa

Prof. A. D. Rao Indian Institute of Technology Delhi, Delhi

Dr. M. Baba Former Director, Centre for Earth Science Studies, Thiruvananthapuram, Kerala

Dr. S. Satheesh Shenoi Former Director, Indian National Center for Ocean Information Services (INCOIS), Hyderabad

Dr. Rashmi Sharma Space Applications Centre (SAC), Ahmedabad

93 Coastal and Open Ocean processes (COOP)

Invited Talks

INVITED TALK 1: Ocean Observations, information and Advisory services

Dr. Srinivasa Kumar

Indian National Center for Ocean Information Services (INCOIS), Hyderabad

INVITED TALK 2: Local Ocean-atmosphere Interactions associated with the Indian Monsoon Multi-decadal Mode

Prof. B.N. Goswami

Cotton University, Guwahati

INVITED TALK 3: Sustainable Indian seas through enhanced biological research

Dr. N. Ramaiah

Former Chief Scientist, National Institute of Oceanography (NIO), Goa

INVITED TALK 4: Satellite Based Ocean Observing and the Blue Economy

Dr. Prakash Chauhan

Indian Institute of Remote Sensing (IIRS), Dehradun Coastal and Open Ocean processes

Decadal Shoreline Morphological Changes Using Satellite Images of Goa Coast ORAL OSICON2021/3 Shanmuga Priyaa S, Aruna Kumar Avula, Basanta Kumar Jena, M. V. Ramana Murthy Coastal and Environmental Engineering Division, National Institute of Ocean Technology, Chennai, India

The study on shoreline morphology is an important tool to identify the causes and the impacts along the coast due to coastal process which helps in securing the ecosystem and future development. The shoreline undergoes severe interventions of anthropogenic activities and naturogenic processes that causes erosion and accretion. This study aims to analyse the shoreline morphological changes over five decades of the Goa coast using remote sensing and GIS approach. In this study, the shoreline morphological analysis has been carried out using weighted linear regression method of Digital Shoreline Analysis System tool with the shoreline inputs from satellite images of spatial resolution ranging from 5m to 60m (Resourcesat, Landsat and Sentinel satellite sensors). The land use land cover has been derived using image classification technique for each decade and the results has been validated with the published maps and ground truthing. The shoreline change analysis for the period 1972 to 2020 using satellite images along the Goa coast indicates 12.5% of the coast is eroding, 20.1% of the coast is accreting and 67.4% is stable. The erosion spots along Goa coast have been identified at Keri, Tiracol, Anjuna, Ashwem, Agonda, Talpona & Polem and the accretion spots at Arambol, Miramar, & Cavelossim from the shoreline change analysis for the period from 1972 to 2020 from the satellite images. The results of shoreline change analysis by various other organization have also been compared. In this study, an integrated approach of geomorphology, land use land cover changes have been assessed for the corresponding shoreline changes along the Goa coast for each decade. The novelty of this work lies with the comparison of the decadal changes of land use land cover and its impact on the morphology of the shoreline of Goa coast.

95 Coastal and Open Ocean processes

Experimental Study on Wave Transmission and Run-up over Submerged Vegetation QUICK ORAL Muni Reddy M.G, Giridhar G., Ganesh A. OSICON2021/17 Civil Engineering, Andhra University, Visakhapatnam

Coastal vegetation is increasingly being considered as a possible alternative for costal protection as the most natural system and is sustainable. The “bio-shield” also efficient in the conservation of beach and also act as a buffer zone in reducing the energy from ocean waves falling upon beach. In addition, coastal vegetation could also have positive impact on stability of shore line. It has been generally agreed that vegetation increases flow resistance, changes backwater profiles, and modifies sediment transport and deposition. The present study is an experimental work carried out using three different submerged vegetation models rigid, rigid with roots and flexible vegetation. Comparison of the wave characteristics i.e., wave transmission (KT), wave run-up (Ru) and vegetation flow parameters are analyzed in this study. Wave transmission decreases with relative water depth (d/Lo) for flexible vegetation, where as increases for rigid vegetation for different values of

Hi/lv (1.0, 0.667, 0.40 and 0.267). Wave run-up decreases with relative water depth for different values of Hi/lv. Predictive equations were proposed for transmission coefficient (KT) and runup (RU/Hi) for three different vegetation configurations. In the present study, the resistance is investigated with respect to Reynold’s number

(Re), relative stem spacing (eL /d) and Vegetation Flow Parameter (VFP) of the vegetal patch. The Vegetation Flow Parameters considered in the present study not only accounts for the ﬂexural rigidity of the vegetation but also for the width of the green patch Wv, ﬂow depth h the diameter of the vegetation d and vegetation roots. The present investigation was carried out for VFP from 10 to 430 and the corresponding Manning’s n varies from 0.04 to 0.085. Comparing with previous results, the presnt study covers the range beyond the ranges of earlier investigations.

96 Coastal and Open Ocean processes

Oxidised volatile organic compounds in the Indian Ocean and Southern Ocean marine boundary layer ORAL OSICON2021/22 Anoop Mahajan, Swaleha Inamdar Indian Institute of Tropical Meteorology, Pune

Glyoxal and formaldehyde are important intermediate species formed by the oxidation of common biogenic and anthropogenic volatile organic compounds such as isoprene, toluene, and acetylene. Although they have been shown to play an important role in urban and forested environments, their role in the open ocean environment is still not well understood, with only a few observations showing evidence for its presence in the open ocean marine boundary layer (MBL). In this study, we report observations of glyoxal from five field campaigns in the Indian Ocean and the Southern Ocean. The measurements are made with multi-axis differential optical absorption instruments, which are highly sensitive to these species. We report a large range of values from several parts per billion close to the continental regions to very low values in the open ocean. This work support previous suggestions that the currently known sources of glyoxal are insufficient to explain the average MBL concentrations. This suggests that there is an additional missing source, more than a magnitude larger than currently known sources from the air-sea exchange, which is necessary to account for the observed atmospheric levels of the OVOCs. There- fore, it could play a more important role in the MBL than previously considered, especially in the open ocean environment.

97 Coastal and Open Ocean processes

The Spatial and temporal variability of OH minimum over Indian ocean QUICK ORAL Ardra D.1, Jayanarayanan Kuttippurath2 OSICON2021/44 1Department of Physical Oceanography, Cochin University of Science & Technology, Kochi; 2Centre for Oceans, Rivers, Atmosphere and Land sciences, Indian Institute of Technology Kharagpur

As OH is the cleaning agent of the atmosphere, reduction in its amounts in the troposphere has a concern or atmospheric pollution and its transport across latitudes. Also, the changes in OH amounts have significant impact on health, food security and climate. Our analysis with OH measurements retrieved from satellite measurements over the past 14 (2005–2018) years exposes an OH minimum in In- dian Ocean, the eastern Bay of Bengal at 6◦–14◦N and 92◦–95◦E. The Indian Ocean OH minimum reaches to a hole situation in summer (June–July, about 0.3–1 ×104 mol/cc), and the second minimum appears in spring (April, 6–8 × 104 mol/cc), and therefore, the OH hole in the Indian Ocean is seasonal. The hole and the secondary minimum of OH are recurring and occur in all years. As OH chemistry is connected to tropospheric ozone, the ozone minimum drives the OH minimum or hole over the Indian Ocean too, as found in the western Pacific. In general, the biomass burning and thus, distribution of CO has a profound influence on the OH distribution in this region as south Asia is one of the largest hotspots of global biomass burning. Henceforth, the ozone minimum in summer and biomass burning peak in March- April primarily drive the OH hole and OH secondary minimum in the respective seasons. The El Niñoand La Niñaevents also control the tropospheric ozone and CO distribution, and thus the OH minimum. This is why there was no OH minimum in 2010 as it was a La Niñayear. Therefore, this study reveals a seasonal OH hole in the Indian Ocean, which is very likely to influence air quality and stratospheric ozone amounts in future. It also reveals the impact of air pollution on stratospheric tropospheric exchanges of race gases, and amplification of air pollution over remote places such the Indian Ocean.

98 Coastal and Open Ocean processes

Role of sea surface temperature anomalies of Arabian Sea in extreme weather events at western coast of Indian subcontinent ORAL OSICON2021/60 Niket Shastri1, K. N. Pathak2 1 Department of Physics, Sarvajanik College of Engineering and Technology, Surat , Gujarat; 2Department of Physics, Sardar Vallabhbhai Institute of Technology, Surat, Gujarat

A signiﬁcant area of uncertainty in weather and climate exist due to our limited understanding of near-surface ocean processes and their interactions with the atmosphere, land, and ice systems. These air-sea exchanges are sensitive indicators of changes in the climate system. Sea surface temperature and pressure are the key parameters in this air-sea interaction. In this research paper we studied the sea surface temperature anomalies in Arabian sea and occurrence of extreme weather events at western cost of Indian subcontinent. We established the crucial and impactful role of sea surface temperature anomalies in occurrence of extreme weather events.

99 Coastal and Open Ocean processes

Validation of CMIP6 with the observations of SST in the Bay of Bengal QUICK ORAL V. Kumar, A.P. Joshi, H.V. Warrior OSICON2021/80 Department of Ocean Engineering and Naval Architecture, IIT Kharagpur

In the present study, we evaluate the representation of sea surface temperature of 22 different global climate models (AOGCMs) from Climate Model Intercompari- son Project Phase 6 (CMIP6). We use observations from remote sensing satellites, agro floats, and basic performance metrics to quantify the ability of the AOGCMs to replicate observed sea surface temperature(SST) of the time-mean, inter-annual variability, and climatology. Bay of Bengal climate is greatly influenced by monsoon over the year, being closed from the land around three sides and receiving massive freshwater input make this region challenging to understand variation in seawater parameters. We demonstrate a statistical multicriteria approach for selecting the best performing models for resolving regional variabilities of this region. Statisti- cal methods include correlation coefficient, root mean square error, average error, absolute average error, reliability index, model efficiency factor, cost function, and percentage bias. Most of the climate models cannot resolve the surface temperature dynamics of this region. These models might be performing excellently for the other regions in the world ocean, but eight models perform in-sync with satellite and Argo floats data. Best models are picked based on the performance evaluated against gridded observational data on 1o × 1o spatial and monthly temporal scale. Results have provided insight into each of the model biases, time series, and statistical properties addressed by them in the evolution of climate models. Further, we analyze the depth-wise variation of seawater temperature and then project the SST for four CMIP6 Tier 1 scenarios (SSP126, SSP245, SSP370, and SSP5.85).

100 Coastal and Open Ocean processes

Aerosol distribution over the tropical Indian ocean and the role of atmospheric thermodynamics QUICK ORAL A. A. Shaikh1, N. Shaikh1, S. Hulswar1,2, H.B. Menon1 OSICON2021/90 1School of Earth, Ocean and Atmospheric Sciences, Goa University, University Goa; 2Centre for Climate Change Research, Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune

Aerosol Optical Depth (AOD500) and Black Carbon (BC) mass concentrations had been observed on-board ORV Sagar Nidhi during International Indian Ocean Expedition- II (IIOE-II). The Expedition was conducted during 6th to 27th December 2015 in the tropical region of Indian Ocean along 67oE and between 13oN to 15oS. Microtops II sunphotometer and Aehtalometer had been used to generated AOD500 and BC mass concentrations respectively. Along with these observations, atmospheric parameters were studied using a handheld AWS, that measured the temperature, pressure, wind speed and wind direction. Dr. Pisharoty Radiosonde (B-3) were launched at 11 predeﬁned stations. The aerosol data were analyzed to understand their dynamics and associated shortwave aerosol radiative forcing. Aerosol concentration decreased from station 1 (near continent) to station 8 (open ocean). Second order derivative of Angstrom exponent, α’, was 2.52±0.38 at station 1, indicating that atmosphere was loaded with accumulation mode aerosols, whereas, α’ was -1.52±0.86 over the open ocean region showed dominance of coarse mode aerosols. Low Convective Available

Potential Energy (CAPE) and Maximum Theoretical Updraft Velocity(W max) and higher Convective Inhibition Energy (CIN) indicated stable atmospheric condition. This resulted in increase in aerosol concentration over the region. Similarly, lower values of Precipitable water (PWAT) added to higher aerosol concentration due to stagnation of aerosols in absence of wet deposition. While, regions with unstable atmospheric conditions displayed lower aerosol concentration, Higher concentration of aerosols at station 1 led to high atmospheric forcing (11.46 Wm−2 ), whereas, an average forcing of 2.25 Wm−2 was observed over the open ocean region. With decrease in aerosol concentration over the open ocean, 80% less atmospheric forcing was observed when compared to station 1. The rate at which the atmosphere was heating at station 1 was 0.12 k day−1 , owing to the eﬀect of anthropogenic aerosols, where, average heating rate over the open ocean region was 0.022 k day−1.

101 Coastal and Open Ocean processes

Assessment of Nutrient Bioavailability and Trophic Status of Beypore Estuary, Southwest India QUICK ORAL Rose Santhosh, Renjith K. R., Vivek B., Ihjas K., Digila Rani M. and Celine OSICON2021/92 George Centre for Water Resources Development and Management (KSCSTE-CWRDM),Kunnamangalam, Kozhikode

Eutrophication driven by large-scale anthropogenic alterations of phosphorus and nitrogen cycles has become a major environmental problem in the coastal ecosystems. Chaliyar River is the fourth longest river in Kerala state with a length of 169 km and total drainage area of 2933 km2 and joins the Arabian Sea at Beypore. The Beypore estuary had been subjected to severe pollution due to effluent discharge from the Mavoor Gwalior Rayons Factory causing severe damage to the aquatic resources of the estuary. The Kavanakallu Regulator cum bridge constructed in 2000 to prevent the salinity intrusion in the upstream has slowed down the river and obstructed the seasonal washing of the pollutants downstream to the sea; severely affecting the biodiversity. The recent studies found that the estuary is ecologically fragile and hypoxic and warrants a detailed investigation on the health of the estuarine environment. Surface and bottom water samples and surface sediments were collected from 10 stations in the Beypore estuary during December 2020 and February 2021, representing the post and pre- monsoon seasons, respectively. Total dissolved phosphorus ranged from 20.26 to 166.37 µg/l and total nitrogen varied from 0.196 to 8.82 mg/l. Concentration of nutrients were found be higher in the bottom water, in general. Trophic status assessment of the estuary using the eutrophication criteria revealed eutrophic nature with respect to nutrients. The distribution of nutrients along the salinity gradient in the estuary showed a positive trend, suggesting an internal loading. Sequential extraction of nutrients in the surface sediments revealed that the bioavailable fractions were significantly higher and were irrespective of the granulometry. The active internal buffering of nutrients in the estuary underlines that the surface sediments play a significant regulatory function through their storage and buffering of nutrients. Hence sedimentary stock assessment in these shallow transitional water bodies is indispensable for their sustainable management.

102 Coastal and Open Ocean processes

Geographical Mapping System (GMS): An improved GIS in Disaster Management ORAL OSICON2021/98 Sanjaya Kumar Sarangi, Mrutyunjaya Panda Utkal university, Bhubaneswar,INDIA

Recently the practice of location based services is rising due to its huge range of applications in the science and technology. Mainly, the Geographic Information Systems (GIS) and its applications are mainly useful for the sustainability of technology and currently leading a major role in preparedness of disaster management systems. As compare to major advantages, it has also some security issues like link stability due to mobility in nature and failure of data security due to dropping of signal strength. The specified communication hazards can be solved by using a Geo- graphical mapping system (GMS) rather than GIS and its security parameters. This paper is enabling the reliable of node mobility and link stability in the geographical region by mapping the expanded network size and its communications range as compare to previous network model and Security system. This reliable communication is mapped between multiple clusters by defining significant information through resources by serving in unstructured, semi-structured and structured network model and spatial information from the randomized regions. With this, researchers may able to find the flexibility of designing and developing a strong link with various mobility parameters and security aspects for GMS.

103 Coastal and Open Ocean processes

Black Carbon characteristics over Indian ocean sector of the southern ocean ORAL OSICON2021/113 Rohit Srivastava, A. Asutosh, P. Sabu, N. Anilkumar National Centre for Polar and Ocean Research, Ministry of Earth Sciences (MoES), Goa

Black Carbon (BC) is an absorbing aerosol that has a considerable influence on the Earth - Atmosphere radiation balance and thus climate. The variation of BC mass concentration and contribution of fossil fuel and biomass burning have been investigated over the Indian Ocean sector of the Southern Ocean from 23 January to March 07, 2020. BC masses were found to decrease from 450 to 150 ng m−3 between 23.3oS to 41oS latitude. Further, an increase in BC mass by > 250 ng m−3 was found till 50oS which could be attributed to trap in cyclonic wind and transport of air parcel from the southern part of African and Eastern part of Madagascar regions. BC mass was found higher (250 - 350 ng m−3) in the latitude range of 57-60oS which could be due to convergence of north-westerly and south-easterly winds. The BC was dominated by fossil fuel contribution (> 80%) during half of the total observations in the southern oceanic region, while biomass burning BC was also found significant ( > 20%) in one-fifth of observations. The biomass burning contribution showed an inverse relation with BC mass, suggesting the increase in BC was due to fossil fuel combustion. Higher BC mass near the Antarctic coast suggested that the coastal Antarctic region act as an accumulation zone of BC. The higher amount of BC in the southern ocean and near the Antarctic coast can lead to a crucial impact on Earth’s radiation budget and can significantly alter the albedo of sea-ice near the Antarctic coast.

104 Coastal and Open Ocean processes

To study the inﬂuence of Indian Ocean Dipole on Southern Hemisphere circulation during austral spring QUICK ORAL Shrutee Jalan1, Pranab Deb2 OSICON2021/131 1Department of Marine Sciences, University of Calcutta; 2Centre for Oceans, Rivers, Atmosphere and Land Science, Indian Institute of Technology, Kharagpur

The Indian Ocean Dipole (IOD) is an ocean-atmosphere coupled phenomenon associated with anomalous sea surface temperature (SST) and zonal wind along the equatorial Indian Ocean. Studies show that convective anomalies in response to these SST patterns can set off large-scale Rossby waves that can modulate extratropical circulation in the Southern Hemisphere (SH). However, a short observational period limits our ability to quantify the influence of IOD on the extratropical SH. Here, we use the pre-industrial control data (100 years) of a fully coupled general circulation model from Phase 5 of the Coupled Model Intercomparison Project (CMIP5) to analyse the IOD influence on the extratropical SH during austral spring. The Southern Annular Mode (SAM) and El Niño- Southern Oscillation (ENSO) are the dominant modes of atmospheric variability over SH. Hence, to isolate the influence of IOD, we first select all the years with the positive phase of the IOD (IOD+), then divide them into two groups - SAM positive (SAM+) and SAM negative (SAM-) years, based on the polarity for SAM. We remove the ENSO impact by considering ENSO neutral years only. Composites of circulation anomalies for these two groups of years (IOD+SAM- and IOD+SAM+) plotted at 850 hPa (Z850) and 250 hPa (Z250) are of the same sign, only varying in magnitude, suggesting a barotropic response. During IOD+SAM- years, negative geopotential height anomalies extend over the mid-latitudes with two peaks - one centred around 60oE and the other around 160oE. At Z250, the magnitudes of these anomalies intensify. Additionally, there exists a negative geopotential height anomaly over the Antarctic Peninsula. In contrast, during only SAM- years, the anomalies in mid-latitudes shift eastward with absence of anomaly over Antarctic Peninsula. During IOD+SAM+ years, the geopotential height anomaly over mid-latitudes shows two positive anomaly centres around 60oW and 170oE. At Z250, alternating positive and negative geopotential height anomaly centres appear across the mid-latitudes which is absent in only SAM+ years. Furthermore, the westerly winds are highly non-uniform and undu- lating in comparison to SAM+ years.

105 Coastal and Open Ocean processes

Trends in tropical cyclone rainfall over the Bay of Bengal during the past two decades QUICK ORAL R. Harikrishnan1,2 , M. K. Roxy1 OSICON2021/134 1Indian Institute of Tropical Meteorology (IITM), Pune, India 2Department of Atmospheric and Space Sciences, Savitribai Phule Pune University, Pune, India

While there are several studies in understanding and quantifying the rainfall associated with cyclones over the North Indian Ocean, still there exists a gap in comprehensive studies on cyclone related rainfall over the Bay of Bengal region, and its relationship with climate variability and change. Recent studies reveal a substantial increase in cyclone-related rainfall and the possible role of climate change, over other ocean basins like the Atlantic. In this study, we analyse the changes in the cyclone related rainfall over the Bay of Bengal (BOB) region from 2000 to 2019. Also, we examine the role of ocean warming in affecting the cyclone related rainfall. We used the Global Precipitation Measurement (GPM) mission data and OISST and ERA5 reanalysis SST datasets for the study. Our results show a significant increasing trend in the average and total accumulated rainfall of cyclones (23% for the pre-monsoon and 21% for the post-monsoon)during 2000–2019. A strong correlation between local SSTs two weeks prior to cyclogenesis and cyclonic rainfall was observed, while no significant relationship was observed concerning the intensity of the cyclone. Particularly, the SST anomalies for the pre-monsoon and the average cyclone related rainfall show a positive correlation of 0.48, statistically significant at 95% confidence levels. Meanwhile, the seasonal average SST anomalies of the region during this period show a warming trend with 0.17oC per decade for the pre- monsoon and 0.18oC per decade for the post-monsoon. Overall, the study shows the potential role of SSTs and ocean warming on the increasing trend in cyclone related rainfall over the Bay of Bengal during the past two decades.

106 Coastal and Open Ocean processes

Wave transformation and attenuation along the central Kerala coast of India using Mike21 SW Model QUICK ORAL Vasudevan S., Sajeev R. OSICON2021/136 Department of Physical Oceanography, Cochin University of Science & Technology, Cochin

Wave hindcast studies is an essential prerequisite for ocean engineering, developing coastal infrastructure and management. Due to sparse and infrequent in-situ observations, model data can be used for the assessment of wave climate in offshore and coastal areas and discussed. In the present study, MIKE 21 Spectral Wave model (DHI, 2011) was used and forced with ERA-Interim winds spanning the year of April 2014 to March 2018. The model simulates the growth, decay and transformation of wind-generated waves and swells both in offshore and nearshore areas. During the northeast (NE) monsoon, the growth of wind seas towards offshore and their modification by opposing swells from SW-SSW significantly contribute to reducing the wave height along the coastal region. Wave parameters obtained from the simulations were analyzed to understand the complex wave environment at any given location in the Indian Ocean and the coastal region at 15 m water depth. The model results were validated by the available buoy data in the selected sector. The wave age of the simulated data indicates that the waves along the central Kerala coast are dominated by the young sea with the presence of swell during SW and NW monsoon.

107 Coastal and Open Ocean processes

Temperature sensor location optimization of expendable bathy thermograph using numerical method ORAL OSICON2021/153 Sona M. A., Anshath Hussain N., Vibin M. V. and Anand P. Naval Physical and Oceanographic Laboratory, Kochi

As a part of indigenization and modernization of expendable Bathy Thermograph probe (XBT), the probe was modified to have one inlet flow path in the axial direction and four diverging outlets in the radial direction, at an angle. As the probe descends, the water enters through the inlet and exits through the four outlets. It is very critical to position the temperature sensor in this flow path considering probe’s axial rotation due to tail blades. The temperature that is measured inside the flow path should match with the temperature of the outside water at a particular depth, for accurate measurement. A study is performed using the numerical analysis for estimating the error in temperature for a descending probe due to the positioning of the sensor inside XBT and to optimize the position along the inlet flow path using thermal analysis (ANSYS Fluent). A detailed study is also done to establish the hydrodynamic behavior of probe under axial rotation. The probe is placed in a computational domain (Mesh count 2776957, rotational velocity of 95 rad/s and inlet velocity of 4 m/s) in which the fluid is assigned with a temperature variation relative to that of ocean variability (T{t} = 27oC + 0.5t). For every 1 sec, the temperature changes at the inlet of the domain by 0.5oC, with the simulation time-step being 0.001s. The simulation is carried out to measure the difference in the sensor tip placed at different locations inside the inlet tube and the corresponding free stream location by imparting the temperature variation to the flow. The error was found to be less than the accuracy of the indigenous temperature sensor. Hence, the location number 3 was chosen considering the manufacturing simplicity.

108 Coastal and Open Ocean processes

Atlantic hurricanes of 2020 and the factors inﬂuencing them ORAL OSICON2021/155 Sidha Sankalpa Moharana, Debadatta Swain School of Earth, Ocean, and Climate Sciences, Indian Institute of Technology, Bhubaneswar

The 2020 Atlantic hurricane season was a year of record-breaking hurricane activity in the North Atlantic Ocean that saw an all-time high of 30 named tropical storms, including 13 hurricanes and 6 major hurricanes. There were 10 tropical storms in September only, out of which 5 storms (Paulette, Rene, Sally, Teddy, and Vicky) were simultaneously active in the basin. This study probes into the meteorological features of these five storms, the environmental conditions of the North Atlantic Main Development Region (MDR), and also attempts to explain the factors responsible for such increased hurricane activity. The extreme 2020 hurricane season can be attributed to a favorable environment for cyclogenesis in the MDR region, including convenient low-level relative vorticity, abnormally warm ocean surface water, and extremely low vertical wind shear. The mean sea surface temperature (SST) for September 2020 was 28.69oC, which was ∼0.5oC above the past 30-years climatology. Also, the mean vertical wind shear value for September was 4.93 ms−1, whereas the region’s climatology suggested a value of 12 ms−1. ERA5 data for these parameters for August, September, and October for the last 30 years (1991 - 2020) was analyzed to assess the contribution of these factors in explaining the variability in tropical storm occurrences. Statistical analysis using multiple linear regression with differential SST (difference between mean MDR SST and mean tropical SST), vertical wind shear and relative vorticity as predictors, and the number of tropical storms as response for the 1991 - 2020 period explains 42.8%, 43.4%, and 34.7% variability with 95% significance for August, September, and October, respectively. Furthermore, simple linear regression analysis indicated the differential SST to be the dominant factor which could explain 40% and 30% variability in tropical storm counts for August and October, respectively. However, relative vorticity accounted for ∼42% variability in tropical storm counts for September. The above inferences were confirmed through partial correlation analysis, which enabled isolation of the effect of individual factors. These results showed the increased hurricane activity in the 2020 season to be a consequence of the favorable juxtaposition of all these factors in the North Atlantic basin.

109 Coastal and Open Ocean processes

Spatio-temporal Variability of Bio-optical Properties and Radiant Heating Rate in the Eastern Arabian Sea QUICK ORAL Partha A. Patil, Arjun Adhikari, Harilal B. Menon OSICON2021/167 School of Earth, Ocean & Atmospheric Sciences, Goa University, Goa

In-situ observations and sampling of inherent and apparent optical properties (IOP and AOP) of coastal waters of Eastern Arabian Sea were conducted during April 2008, 2009 and 2010, and in December 2008. The derived AOPs were remote sensing reflectance (Rrs), diffuse attenuation of downwelling irradiance (Kd(P AR)), while IOPs were absorptions of chlorophyll-a (Chl-a), chromophoric dissolved organic matter (CDOM) and total sediment matter (TSM) and their respective concentrations, generated from water sample analysis. To study the effect of OACs on the degree of absorption, radiant heating rate (RHR) was computed after duly incorporating the effect of atmospheric transmission and sea surface albedo on downwelling irradiance.

Based on the variability of Rrs, the study area has been divided into four optical water types (OWTs). The average concentrations of Chl-a and TSM increased from OWT1 to OWT4 in April (0.46 - 3.47 ug/l; 3.23 - 4.52 mg/l) and from OWT1 to

OWT3 in December (0.316 - 0.86 ug/l; 2.5 - 3.3 mg/l), while ACDOM (440) distribution was homogenous in December (ranging from 0.69 to 0.78 /m). Kd(P AR), an index of turbidity of the water column, increased from 0.14 to 0.22 and from 0.12 to 0.25 for OWT1 to OWT3 in April and December respectively, and it was 0.4 in OWT4 during April. Despite such variability, RHR encountered for each classification in April was twice than that of December. For April itself, the RHR for OWT4 waters was 0.08oC/hr, four times that observed for OWT1 waters. Among all the OACs, Chl-a was the major component responsible for radiant heating. Hence a model was developed to estimate the ocean surface heat flux for waters with varying Chl-a concentration. The results show that for a constant wind speed of 1m/s, the difference in heat loss between water column with Chl-a of 0.2 ug/l and 5 ug/l Chl-a amounts to be 9.79 W/m2/day. The paper explains the detailed analysis of spatial and temporal RHR.

110 Coastal and Open Ocean processes

Simulation with Eddy Resolving High Resolution (1/12o)Global NEMO Ocean Model ORAL OSICON2021/169 Imranali M. Momin1, A. K. Mitra1, J. P. George1, M. Martin2, J. Waters2, A. Aguiar2 1National Centre for Medium Range Weather Forecasting, Ministry of Earth Sciences, Noida; 2 Met Oﬃce, FitzRoy Road, Exeter, EX1 3PB, United Kingdom

Nucleus for European Modelling of the Ocean (NEMO) is a modeling framework for ocean state monitoring and its forecast, research activity and climate studies. At National Centre for Medium Range Weather Forecasting (NCMRWF), the NEMO based global high resolution eddy resolving ocean model (ORCA12 tripolar grid) is configured at 1/12th degree resolution. This eddy resolving high resolution model is based on version 3.6 of the NEMO (NEMO v3.6) with 75 vertical levels and version 5.2.1 of Los Alamos National Laboratory Community Ice CodE (CICE 5.2.1) model with multi-layer sea ice thickness. The NEMO v3.6 & CICE 5.2.1 models have a non-linear free surface (cell thickness throughout water column varies with time), improved momentum advection scheme, modified freshwater input to land with enhance vertical mixing at runoff point, Lagrangian Iceberg model (tracking Iceberge), multi-layer thermodynamics. In this study, the eddy resolving high resolution model is initialized on 31-May-2017 and free run up to one month period is performed using the surface boundary fluxes from the NCMRWF Unified Model (NCUM; ∼12 km). The global model set-up, surface boundary fluxes from NCUM and its initial simulation results will be presented in this conference. The simulated temperature, salinity, sea surface height and sea ice concentration from high resolution model will be also compared against various satellite and in-situ observations.

111 Coastal and Open Ocean processes

Mesoscale circulation features on the northwestern Bay of Bengal using HF radars observations QUICK ORAL Anupama Sahoo, Shouvik Dey, Sourav Sil OSICON2021/173 School of Earth, Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar, Odisha

The mesoscale features of surface currents during 2015 are studied using observations from the high-frequency radars (HFR) along the Odisha coast of the northwestern BOB region. Two radars at the Odisha coast are located at Gopalpur and Puri, deployed and maintained by ESSO-NIOT, Ministry of Earth Science (MoES), India. The hourly surface current data with 6 km spatial resolution is obtained from ESSO-INCOIS, MoES provides the opportunity to study the mesoscale oceanic processes with typical horizontal scales of less than 100 km and timescales on the order of a month. In January, southward flow is observed throughout the HFR domain with strong currents from coast to 150 km offshore. In late February, the southward current becomes weak, and transitions are observed. In March, the southern part of the HFR domain showed the northward current, and the northern part showed the southward current. They are associated with one coastal cyclonic eddy near Gopalpur, and another anticyclonic eddy near Puri with a radius around 10 km is noted in the observation. The cyclonic eddy stayed almost at the same location for two weeks with similar intensity. However, the anticyclonic eddy intensified, moved southeastern, and merge with the northward flowing western boundary current (WBC) within a week. In April, the WBC dominated throughout the region till early May. In June, the WBC almost vanished, and a weaker current is observed near the coast in the HFR domain. In the third week, an anticyclonic eddy is observed. In late August, a cyclone eddy is noted in that domain for a week. From October, the southward East Indian Coastal currents are observed, but it is very weak. The year 2015 was a positive Indian Ocean Dipole (IOD) year. Therefore, the second downwelling coastal Kelvin wave was very weak. The study represents the uniqueness of the HFR observation on the monitoring of mesoscale coastal circulation features in the Indian Ocean.

112 Coastal and Open Ocean processes

The Known and Unknown Mysteries of Marine Atmosphreic Boundary Layer under the inﬂuence of a Tropical Cyclone: A Case Study during OCKHI Storm ORAL OSICON2021/177 D. Bala Subrahamanyam1,Roshny S.1,2, Freddy P. Paul1,2, Anurose T. J.3, Radhika Ramachandran1 1Space Physics Laboratory, Vikram Sarabhai Space Centre Department of Space, Government of India Indian Space Research Organisation Thiruvananthapuram; 2Cochin University of Science and Technology Cochin; 3National Centre for Medium Range Weather Forecasting Ministry of Earth Sciences, Noida

Although considerable progress has been made in improving the early predictability of the tropical cyclones, our knowledge of the vertical structure of the marine atmospheric boundary layer (MABL) over a cyclone-affected ocean remains limited. One of the probable reasons for our limited understanding of the MABL during a cyclone is lack of observational database and technical constraints involved in logistic arrangements for in situ measurements of MABL during extreme windy conditions. Therefore, most of our understanding about the vertical structure of MABL during a cyclonic storm comes from numerical simulations. Here, we investigate the impact of a very severe cyclonic storm “OCKHI” on the MABL parameters over the Arabian Sea by using a regional numerical weather prediction model, namely Consortium for Small-scale Modelling (COSMO). Time-series Meteograms of the surface-layer and upper-air meteorological parameters are examined for six distinct locations on the trajectory of OCKHI. Equivalent day analysis on the surface-layer turbulent fluxes over these locations reveals a substantial rise in the magnitude of sensible and latent heat fluxes during the passage of the storm. Surface-layer parameters within the MABL exhibit large diurnal variability during the passage of the storm compared to the normal days. Profiles of thermodynamic parameters indicate a significant dip in the mixed layer heights near the eye of the storm due to the formation of deep convective precipitating clouds. A decline in the mixed layer height during the propagation of the storm was a persistent feature. The present study also provides a conserved variable analysis of the equivalent potential temperature and specific humidity for a diagnostic investigation on the MABL processes and the movement of an air parcel.

113 Coastal and Open Ocean processes

ROMS Simulations of Physical and Biogeochemical Parameters for ’NARGIS’ cyclone in the Bay of Bengal ORAL OSICON2021/178 Tarumay Ghoshal, Arun Chakraborty Department of Civil Engineering, DIT University, Dehradun, Uttarakhand

The most important aspects of the Bay of Bengal (BOB) are its high variability of thermohaline features in temporal and spatial scale and occurrence of frequent cyclones. The basin experiences northeast and southwest monsoon in a year. The semiannually reversing winds during these monsoons are also responsible for circulations in the basin. Also, convective activities developed over BOB lead to prominent tropical cyclones which are very much favored by high sea surface temperature (SST) in the basin. Mostly, these cyclones occur in pre and post southwest monsoon season and few in transition time in between. However, due to poor resolutions of satellite sensors, data gap and lack of insitu datasets for BOB region creates diﬃculty in identifying variabilities of surface and subsurface parameters caused due to these cyclones. Numerical simulations solve these problems with improved initial and boundary conditions either directly obtained from available satellite data or assimilated datasets. One such case study is undertaken for cyclone ’NARGIS’ that formed over BOB and was persistent from 27th April to 2nd May, in the year 2008. Regional Ocean Modeling System (ROMS) has been set up for BOB for simulations of cyclone cases. Multi satellite assimilated SST, temperature-salinity conditions and satellite derived wind forcing have been used in ROMS to simulate for ’NARGIS’ cyclone. Results show prominent eﬀects of wind stress not only on temperature and salinity but also to other biogeochemical parameters as a result of wind induced mixing and upwelling. The result is found to be very prominent especially in cyclone center.

114 Coastal and Open Ocean processes

Future projection of wave characteristics using CMIP6 wind along south Odisha coast ORAL OSICON2021/182 Subhasis Pradhan1, Pratap Kumar Mohanty2, Rabindro Nath Samal1, Madan Mohan Mohanty3, Prabin Kumar Kar2 1Chilika Development Authority, Palashpalli, Bhubaneswar, Odisha; 2Dept. of Marine Sciences, Berhampur University, Berhampur, Odisha; 3National Institute of Ocean Technology, Chennai

To study the impact of climate change on wave characteristics along the South Odisha coast, the spectral wave model was simulated with a larger domain (10oS- 25oN and 40oE-100oE) covering North Indian ocean (NIO) for the period 2013-2040 using CMIP6 wind field of RCP 4.5 (global climate model). The present and future scenarios of wave characteristics in NIO are simulated for the period 2013-2040 using MIKE 21 Spectral Wave (SW) model based on flexible mesh. Fully spectral formulation was chosen to solve the wave action balance equation for the entire domain. The model was simulated for 28 years (2013-2040) providing CMIP6 wind data as input. The u and v wind components of CMIP6 for 2013-2040 were obtained from Earth System Grid Federartion (ESGF) with spatial resolution of 0.5o × 0.5o at 3hr interval. The results were then compared with Buoy data deployed at 17m water depth off Gopalpur. The model derived wave parameters such as significant wave height (Hs), zero-crossing wave period (Tz) and mean wave direction (θm) were compared with similar parameters obtained from wave rider buoy off Gopalpur. The observed wave data at Gopalpur coast were collected from INCOIS, Hyderabad for the period 2013-2020 with some data gaps during cyclonic events and maintenance period. The simulated wave parameters have extracted for Gopalpur coast compare well with observed wave parameters. It is observed that the maximum Hs decreases with time while the mean Hs maintain an equilibrium condition. Impact of climate change on wave characteristics is assessed through Gumbell distribution of Hs, which distinctly shows a slight reduction of wave height with time, but indicates a higher probability of occurrence of Hs ranging between 0.5m to 1m. Wave period remains more or less stable with time while the probability of occurrence of Tz of 6sec is higher with time. Wave direction shows a slightly shift from S-SE to S-SW in the future climate. However, lesser probability of occurrence of S to SE waves with time is observed.

115 Coastal and Open Ocean processes

Inﬂow and spreading of the Red Sea and Persian Gulf water into the western Arabian Sea QUICK ORAL Sankar Prasad Lahiri, Vimlesh Pant OSICON2021/183 Centre for Atmospheric Sciences, Indian Institute of Technology, Delhi

Presence of landmass to the northern tropics and the seasonal reversible of monsoon winds makes the Indian Ocean a unique basin as compared to the other oceans. With the change of wind direction, the circulation pattern reverses in the North Indian Ocean and affects the climate variability and weather over a large region. During summer monsoon, the Indian subcontinent receives plenty amount of precipitation. The Bay of Bengal (BoB) receives surplus freshwater from river discharge and precipitation which results in upper-ocean low salinity in the bay. On the other hand, the Arabian Sea (AS) in the northwestern Indian Ocean experiences higher evaporation than precipitation and low volume of river inflow which makes the AS a high salinity basin. Further, the AS receives high-salinity influx from the Red Sea water (RSW) and Persian Gulf water (PGW). In the current study, the reanalysis data and in-situ observations of temperature and salinity profiles in the AS are utilized to examine the intrusion of high-salinity waters from the RSW and PGW and its transport pathways in the AS. The analysis based on tracking of water mass and currents from surface up to a depth of 1000 m highlights the seasonal variability in the high-saline water mass influx and its spatial distribution in the AS. The RSW and PGW enters in the western AS at different depths ranging from 200-800 m. This intrusion is most abundant in late winter season for the RSW whereas, the PGW does not show a strong seasonality. As this high-salinity water can influence the density induced circulation and ocean stratification, this study attempts to identify the RSW and PGW water masses and associated changes in different regions of the north Indian Ocean.

116 Coastal and Open Ocean processes

Dynamics of mercury in a monsoon fed tropical estuarine system during dry season ORAL OSICON2021/184 Saranya Jayachandran1, Parthasarathi Chakraborty1, Prasad Padalkar1, Lamjahao Sitlhou1, Kartheek Chennuri2 1Indian Institute of Technology Kharagpur; 2CSIR - National Institute of Oceanography

Understanding mercury (Hg) dynamics in an estuarine system is vital because of its bioaccumulation and potential toxicity to the ecosystem. Th is study was carried out in the Mandovi estuary, a representative of a typical monsoonal estuary from the west coa st of India. It describes distribution, sp eciation and mobility of Hg in the estuary during dry period (February), when pollutants reside longer time inside the estuary due to poor river discharge. Further, we investigated the inﬂuence of various parameters like, texture of estuarine surface sed iment, dissolved oxygen, salinity, pH, sedimentary organic matter (SOM), molar carbon to nitrogen ratio, chemical characterization of SOM, and sulphate reducing bacteria, on distribution and speciation of Hg in the estuary. Samples were collected along the length of the estuary from head to mouth. The lowest concentration of methylmercury (MeHg), a neurotxin ) was found at middle of the estuary. There was a decrease in the MeHg concentration as the concentrati on of SOM increased along the estuary. Strong association of Hg with the SOM and formation of stable Hg-SOM complexes were found to decrease methylation in the estuary. A signiﬁcant increase in MeHg production was observed with the rise in the total sedimentary Hg concentration. The coherent variability of the porewater Hg and MeHg in the sediment probably indicates the dissolution of sedimentary MeHg to the porewater. This study suggests that methylation of sedimentary Hg controls the concentrations of Hg in porewater and overlying water column in the estuarine system. Presumably, sediment is the primary source of dissolved Hg in the water column during the dry period in the Mandovi estuary.

117 Coastal and Open Ocean processes

Seasonal and Intraseasonal Variability of Winds and Associated Air-Sea Interaction in the Bay of Bengal from a Moored Buoy Observation QUICK ORAL Sumana Mandal1, Arkaprava Ray1, Sourav Sil1, R. Venkatesan2 OSICON2021/185 1School of Earth, Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar, Odisha; 2Ocean Observation Systems, National Institute of Ocean Technology, Chennai, India

The air-sea interactions in the Bay of Bengal (BoB) are complex due to their geographical location. The basin is influenced by the reversing monsoonal winds, tropical cyclones, and depressions. The present study aims the identification of the transition phases of the monsoonal winds and their intraseasonal variations. The study also analyzed the associated air-sea interaction during 2016 - 2017 using met- ocean parameters measured by the deep ocean buoy (BD12) in the Andaman sea, on the eastern BoB. The deep ocean buoy is deployed and maintained by ESSO-NIOT, Ministry of Earth Sciences (MoES). The observation data is taken from March 2016 to December 2017. A criterion of consistent wind at least for seven days will determine the arrival of northeasterly (NE) and southwesterly (SW) phases. The wind direction changed from NE to SW on May 15 in 2016, whereas transitions of the winds happen early on April 11 in 2017. The observations showed the wind direction changed from SW to NE on November 11 in 2016. In 2017, the transition from SW to NE also occurred early on October 24. An anomaly from December 07 to December 12 is noted, showing maximum wind speed and the wind direction due to severe cyclonic storm Vardah. The drop in atmospheric pressure also supports the influence of cyclone. Within the SW and NE winds regime, 10 - 20 days and 30 - 60 days interseasonal variability are identified from the wind observation. The study also showed the variability of sea surface temperature and salinity within a season. The study presents the importance of time series observation in the air-sea interaction in different seasonal and intra-seasonal scales.

118 Coastal and Open Ocean processes

Observations of currents in the Sri Lankan dome using in-situ, satellite, and re-analysed data QUICK ORAL Athira K1, Rajith K2, Harikrishnan M2, Dominic Ricky Fernandez2 OSICON2021/191 1Kerala Univ. of Fisheries & Ocean Sciences (KUFOS), Panangad, Kochi; 2 Naval Physical and Oceanographic laboratory, Kochi

Surface current measurement using the X-band Radar system were carried out onboard INS Sagardhwani to capture the Sri Lankan Dome in the time of summer monsoon. This is the first of it’s kind surface current measurement in India using the X-band Radar system. North-eastward current were observed on the eastern side off Sri Lanka with magnitude upto 1m/s. Observes Current measurements along 100N were southward at 840E and northward at 860E. The Sri Lankan Dome was observed with its centre around 100N and 850E. SSH data (derived from Copernicus marine environment monitoring) revealed that the Sri Lankan Dome had a diameter of 220 km and maximum current speed of 0.9m/s measured. Sub surface currents from INCOIS-GODAS model data showed that the cyclonic eddy was centered at 84.50E. The vertical velocity currents were upward (4m/day) which was due to upwelling at the core of the cyclonic eddy. Simultaneous data on surface current from different sources such as Ocean Sur- face Currents Analysis - Real Time (OSCAR) data derived from satellite altimeter and scatterometer, the global ocean Surface current from Meteorological & Oceano- graphic Data Archival Centre (MOSDAC), and the surface drifter data from the Global Drifter Program for July 2019 were also used to characterise the surface current features of the area. Comparison of OSCAR and MOSDAC with in-situ data along the diameter of Sri Lankan Dome gives correlation coefficient of 0.77, 0.78 and 0.72, 0.71 for both zonal and meridional components of current respectively. The correlation coefficient for satellite derived datasets exceeds a value of 0.88 and 0.93 for zonal and meridional currents. Comparison of OSCAR and measured data showed that, the correlation is more for zonal component of the current than meridional component. To study small scale features which cannot be resolved by model and satellite data, X-band radar prove a better insight.

119 Coastal and Open Ocean processes

Surface circulation features in the western Aandaman Sea: Observations from HF RADAR ORAL OSICON2021/197 Samiran Mandal1, Sourav Sil1, Avijit Gangopadhyay1,2 1School of Earth, Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar, India; 2School for Marine Science and Technology, University of Massachusetts, Dartmouth, MA, USA

The characteristics of surface currents during November 2016 - October 2017 are studied using observations from the high-frequency radars (HFRs) and a moored buoy (BD12) along the western Andaman Sea (WAnS). The comparison of HFR currents with the collocated currents from BD12 shows a high correlation (>0.78) on a daily scale for both horizontal components. Moreover, the daily HFR currents compared reasonably well to the daily algorithm-derived currents (ADCs) using composites from multiple satellites for both the zonal and meridional components. The reversal of currents is observed during the northeast (November - February) and during southwest (June - October) monsoon with the mean current magnitudes of 0.41 m/s northward and 0.22 m/s southward, respectively, which is predominantly influenced by the local wind stress. The seasonal reversal of currents leads to the exchange of waters between the WAnS and the Bay of Bengal through the eleven- degree channel, which is primarily due to the meridional Ekman mass transport. A sub mesoscale coastal anti-cyclonic lee eddy is also observed in the wake of the flow around little Andaman Island from the HFR surface circulation maps during 4th - 9th August 2017, with a mean radius of ∼11 km. The broad-scale circulation pattern from the ADCs reveals that the surface currents flowed eastward through the eleven- degree channel during the entire month of August, except for 4th -10th August, when the lee eddy obstructed this cross-channel exchange. Negative values of normalized vorticity (-0.70), divergence (-0.15), Okubo-Weiss parameter, and smaller values of strain characterizes the anti-cyclonic eddy. A term-by-term vorticity balance analysis suggests that local wind stress curl and vortex stretching play more important roles in the evolution of the lee eddy than does advection. To conclude, this study highlights the capability and need of higher resolution datasets from multiple data sources (HFR and satellite maps) to resolve the dynamical features related to the sub-mesoscale coastal eddies.

120 Coastal and Open Ocean processes

Understanding iodine emissions in the Indian and Southern Ocean marine boundary layer ORAL OSICON2021/198 Swaleha Inamdar1,2, Liselotte Tinel3, Qinyi Li4, Alba Badia5, Alfonso Saiz-Lopez4, Kirpa Ram2, Rosie Chance6, Lucy Carpenter6, Anoop Sharad Mahajan1 1Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune; 2Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi; 3IMT Lille-Douai, 941 Rue Charles Bourseul, CS 10838, 59500 Douai, France; 4Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Madrid, Spain; 5Institute of Environmental Science and Technology (ICTA), Universitat Aut`onomade Barcelona (UAB), Barcelona, Spain 6Wolfson Atmospheric Chemistry Laboratories, Department of Chemistry, University of York, UK

The presence of iodine in the atmosphere, though as a trace element, is important for the health and well-being of humans via ingestion of deposited iodine in the soil through vegetation. Lack of iodine in the human diet is linked to endocrine malfunction, neurological damage, developmental delays and death in children. Reactive iodine is known to cause depletion of tropospheric ozone

(O3) via catalytic destruction, and significantly impact atmospheric photochemistry. Iodocarbons released from the ocean such as CH3I, CH2ICl, CH2I2 contribute to around 20% of the global iodine flux to the atmosphere. Whereas inorganic iodine emissions of HOI and I2 released from − the heterogeneous reaction of iodide (I ) dissolved in seawater with O3(gas) at the sea surface is considered as the primary source of atmospheric iodine contributing to 80% of the emissions. Active iodine chemistry in the marine atmosphere is confirmed by the detection of iodine monoxide

(IO) as HOI and I2 quickly photolyse to release I atoms which further reacts with O3 forming IO. During several expeditions in the Indian and Southern Ocean via the 2nd International Indian Ocean Expedition (IIOE- 2) and the Indian Scientific Expeditions to the Southern Ocean (ISESO), we observed the near-ubiquitous presence of IO in this region. However, estimated fluxes of HOI and I2 using a global parameterisation scheme could not explain the detected IO in this region. Model simulations using a regional model for the Indian Ocean region show that to match the observed IO mixing ratio the inorganic iodine emissions need to be reduced by 40%. Further, these simulations highlight that organic iodine emissions alone do not reproduce atmospheric IO levels highlighting the need to improve inorganic iodine parameterisation. Here, we attempt to reproduce the surface abundance and vertical profiles of atmospheric IO in the Indian and Southern Ocean marine boundary layer by adjusting the strength of inorganic and organic iodine emission. These simulations are performed using a one-dimensional model incorporating inorganic emissions from global parameterisation and compiled emission inventories for iodocarbons.

121 Coastal and Open Ocean processes

Third Revision of the Bottom-up Global Surface Seawater Dimethyl Sulﬁde Climatology (DMS-Rev3) ORAL OSICON2021/199 Shrivardhan Hulswar1, Rafel Simo2, Mart´ıGal´ı3, Tom Bell4, Arancha Lana5, Swaleha Inamdar1,6, Anoop S. Mahajan1 1Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune, India ; 2Institut de Ci`cnciesdel Mar (CSIC), Barcelona, Catalonia, Spain ; 3Barcelona Supercomputing Centre (BSC), Barcelona, Catalonia, Spain ; 4Plymouth Marine Laboratory (PML), Plymouth, UK ; 5Institut Mediterrani dEstudisˇ Avan¸cats(IMEDEA, UIB-CSIC), Esporles, Balearic Islands, Spain ; 6Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, India

We updated the estimation of the bottom-up global surface seawater dimethyl sulfide (DMS) with an updated, DMS-Rev3 climatology. It is the third of its kind and includes five significant changes from the last climatology, ’L11’ that was released about a decade ago. The first change is the inclusion of new observations that have become available over the last decade, i.e., the total number of observations included in DMS- Rev3 are 872, 427 as compared to 47, 313 data points used in the last estimation (∼18-fold increase in raw data). The second is significant improvements in data handling, processing, and filtering, to avoid bias due to different observation frequencies which results from different measurement techniques. Thirdly, we incor- porate the dynamic seasonal changes observed in the geographic boundaries of the ocean biogeochemical provinces. The fourth change is refinements in the interpola- tion algorithm used to fill up the missing data. And finally, an upgraded smoothing algorithm based on observed DMS variability length scales (VLS) help reproduce a more realistic distribution of the DMS concentration data. The results show that DMS-Rev3 estimates the global annual mean DMS concentration at ∼1.87 nM, i.e., about 23% lower than the current bottom-up ’L11’ climatology. However, significant regional differences of more than 100% are observed. The global sea to air flux of DMS is estimated at ∼27 TgS yr−1 which about 4% lower than L11 although, like the DMS distribution, large regional differences were observed. The largest changes are observed in high concentration regions such as the polar oceans, although oceanic regions which were under-sampled in the past also show large differences. DMS-Rev3 reduces the previously observed patchiness in high productivity regions.

122 Coastal and Open Ocean processes

Impact of COVID-19 associated lockdowns on the year-to-year variability of oil pollution along the Eastern Arabian Sea ORAL OSICON2021/200 V. Trinadha Rao, Suneel V. , Istuti Rajavanshi, Alex M.J, Antony P Thomas CSIR-National Institute of Oceanography, Dona Paula -403 004, Goa

Oil spills from both ships and oil fields are significant in the Eastern Arabian Sea (EAS). This study investigates the year-to-year variability in the occurrence and abundance of oil spills in the EAS using the sentinel-1 (Synthetic Aperture Radar) imagery to identify the potential oil spill hotspot regions. The data acquired during four consequent years from 2017 to 2020 (298 images) reveals three oil spills hot spot zones along the west coast of India; and named as Region 1 (Off Gujarat), Region 2 (Off Maharashtra), and Region 3 (Off Karnataka and Kerala). The ship- based oil spills were dominant over regions 1 and 3, and the oil field based were dominant over Region 2. The data further depicts that the occurrence and abundance of oil spills were relatively minor with the occupied area of 7.20km2 (only 2 % of oil spills) during 2020 (March-May) than other years over Region 1. Thus, suggesting that the limited fishing vessels and other local cargo operations during COVID-19 associated lockdown implemented in India might have been conducive to fewer oil spills. Whereas, the year-to-year abundance of oil spills over Regions 2 and 3 are not significantly varied (207.6km2 and142.2km2 respectively), further suggesting the influence of oil exploration and international tanker routes which were in operation during the lockdown period.

123 Coastal and Open Ocean processes

Numerical interaction on tide, wind, wave & current oﬀ Gulf of Khambhat ORAL OSICON2021/201 Susant Kumar Misra, J. Guru Prasath, R. C. Bragath, P. Chandramohan Indomer Coastal Hydraulics., Chennai

Due to increasing industrial development, the maritime activities along the coastal stretches of Gulf of Khambhat (GoK) have increased tremendously and it is necessary to understand the morphology and effect of oceanographic parameters. The GoK, also known as the Gulf of Cambay, is a bay on the Arabian Sea coast of India, bordering the state of Gujarat. The GoK is about 200 km long, about 20 km wide in the north and up to 70 km wide in the south. Major rivers draining into the GoK are the Narmada, Tapti, Mahi and Sabarmati that form estuaries in the gulf with fringing creeks. The GoK is the largest tidal region in India with the spring tidal range exceeding 9 m. Consequently, the tidal currents are also stronger with the maximum current speed reaching 3 m/s during spring tide and 2 m/s during the neap tide. Based on past cyclonic records, the intensity of a cyclones inside the bay is less compared to other open sea coast. It is observed that wind speeds is high (40 knots) during the month of May, June, July, August. Wind speeds are found to be low during the month of February (4 knots). During the rest of months, i.e., January, March, April and September to December the wind speed is moderate (15 knots). The northern stretches of the Gulf have insignificant effect from waves. Studies have shown that they don’t influence from offshore to an extent as they do in open sea coast. Studies related to wind, waves, tides and currents is required in a holistic manner to understand the hydrodynamics of the region. Wave hindcasting (forecasting) or wave simulated models estimate the evolution of the energy of wind waves generated by atmospheric wind blowing over the sea surface. Based on the study conducted the waves at Open Gulf reaches up to 6 m and gets attenuated to less than 1 m reaching to the northern part of the GoK. The study shows that the significant wave height remains less than 2 m for 98% times. The peak wave period remains between 2 and 8 s for 80 % of times. The predominant wave direction remains between South and SSW for 82% of times. From the above context, the author’s has setup numerical model to study the interaction of tide, wind, wave & current in GoK. The model results seen to be in good agreement with measured data and available estimates published in the past literatures.

124 Coastal and Open Ocean processes

Sustainable management of shoreline near Mahabalipuram ORAL OSICON2021/211 J. Guru Prasath1, Chandramohan2 1Indian Institute of Technology, Madras; 2Indomer Coastal Hydraulics Pvt ltd.

Waves breaking near shore in the surf zone mobilize sediments around the breaker point, and currents generated by these breaking waves transport sediments along (alongshore sediment transport) and across the coast (cross shore sediment transport).The transport of sediments are powered primarily by the energy of the breaking waves, and are also often influenced by tide and wind driven currents which finally shape the resultant morphology of the coastline. This highly fragile near-shore morphology continuously changes responding to environmental forces induced by wind, waves, currents, tides and water level variations and also to sediment inputs from rivers, sand dunes, mining, nourishment, dredging and dredge disposals. Spatial and temporal variations in the supply of sediments or obstruction to sediment movement along the coast imposed by coastal structures leads to significant alterations in the shoreline profile, sometimes requiring drastic and expensive interventions to save important and critical coastal lands. Mahabalipuram, situated on the sea shore about 55 km south of Chennai is a well-known world heritage monument of UNESCO dating its origin back to the 8th Century AD. The coastline of Mahabalipuram region consists of long straight continuous open beaches oriented approximately N-S with a slight inclination to the coast. The archeologically significant shore temple structure is protected by a seawall, the presence of which has resulted in the beach getting eroded in front of the seawall structure. The design of many coastal structures are based on a number of assumed empirical relationships and deterministic numerical models which have become important tools for investigating coastal processes and for coastal engineering design. These tools are often used for making expensive engineering policy decisions. A detailed field study undertaken before the onset of the North East Monsoon at Mahabalipuram shows that the behavior of sediment movement and the influence of forcing parameters are highly complex and can vary appreciably even within a short duration of time. A sustainable soft solution is presented and model runs are simulated to predict if the shoreline can be managed with minimal impact on aesthetics and if the sediment supply can be conserved during periods of high erosion using soft measures.

125 Coastal and Open Ocean processes

Mixing zone analysis of brine wastewater disposal from desalination plant at Kadmat, Lakshadweep Islands ORAL OSICON2021/213 U.S.Panda1, D.Shyamala Varthini2, S.K. Raju1, Anirban Das2, M.V. Ramana Murthy1 1 National Centre for Coastal Research, NIOT Campus, Chennai; 2National Institute of Ocean Technology, Pallikaranai, Chennai

Kadmat Island, a coral island of the Union Territory Lakshadweep is 9.3 km long and 0.57 km wide, with a total area of 3.20 sq km. The island with beautiful shallow lagoon and long sandy beaches is a place of tourist attraction. Due to lack of storage, and the limited groundwater storage capacity, freshwater is a precious commodity in this remote islands. As an alternative source of drinking water, a 50 KLD desalination plant with reverse osmosis (RO) water purification technology was proposed to meet the water requirement. In RO technology, the reject brine effluent having concentration about 1.5 times more than the original sea water salinity will be discharged into the ocean. Kadmat being a pristine environment, the impact assessment of brine water discharge from this plant is crucial to ensure that there are no impact on the sensitive ecosystems. In this study, an investigation was undertaken to assess the thermo-haline effluent discharge scenarios. A submerged multi-port staged diffuser was evaluated through a near-field dilution and mixing zone model. A 3-dimensional hydrodynamic and advection-dispersion numerical model was used to analyse far-field transport and effluent fate. Assessment of impacts of different scenarios related to possible changes to waste heat characteristics has been carried out to determine the most viable outfall configurations, and discharge scenarios that would have the least impact on the critical ecosystem. The study will be helpful for environmental engineers in the design and implementation of outfall diffusers and desalination plant locations.

126 Coastal and Open Ocean processes

Impact of assimilating satellite derived sea surface salinity data from SMOS, Aquarius and SMAP in a high resolution ocean circulation model for the Tropical Indian Ocean: An Observing System Experiment framework ORAL OSICON2021/217 Smitha Ratheesh, Neeraj Agarwal, Rashmi Sharma 1Oceanic Sciences Division, Space Applications Centre, Ahmedabad-380015 ; 2Atmospheric and Oceanic Sciences Group, Space Applications Centre, Ahmedabad-380015

Data assimilation experiments using sea surface salinity (SSS) observations from three satellites (SMOS, Aquarius and SMAP) has been carried out to assess the observation system impact on simulations in the northern Indian Ocean using an Ocean circulation model. To this end, seven model experiments, with and without SSS assimilation, were conducted and an impact analysis on various simulated model variables was carried out by comparing with in-situ observations. Assimi- lation of SSS data into model resulted in a significant improvement of up to 55% in model surface salinity Root Mean Square Error (RMSE) over control run when compared with in-situ SSS observations from Argo floats. Biases in the simulated sub-surface salinity (below 75 m) were effectively corrected by SSS assimilation. Model simulations, constrained using SSS from SMAP, had maximum improvement in salinity at all depths (reduction in RMSE of ∼ 54% at surface and ∼ 21% at around 40m depth), as compared to other simulations in which single satellite SSS was assimilated. SSS data assimilation from multiple satellites resulted in significant improvement (∼31%) in the halocline region, which was ∼11% more than single satellite assimilation. Model results show the ability of SSS observations in complementing other ocean observation networks. One important observation from this study is that while the impact of assimilating SSS observations from a single satellite was at par with the impact of assimilating SSS observations from two or three satellites in correcting simulated surface salinity, more than one satellite SSS data assimilation was found to be more effective in the deeper layers of ocean.

127 Coastal and Open Ocean processes

Implementation of NEMO based high resolution regional coupled model at the National Center for Medium Range weather Forecasting (NCMRWF) ORAL OSICON2021/220 Akhilesh K. Mishra1, A. Gupta1, I. M. Momin1, A. K. Mitra1, J. M. Castillo2, H. Lewis2 1NCMRWF, Ministry of Earth Sciences, India ; 2Met Oﬃce, U.K.

National Center for Medium Range Weather Forecasting (NCMRWF) is collaborat- ing with Met Office (United Kingdom), to implement a Regional Coupled Environ- mental Prediction (RCEP) system on High Performing Computing (HPC) system ’Mihir’ of Ministry of Earth Science, India. This regional coupled system is comprised of NEMO ocean model, Met Office’s Unified Model (UM) atmospheric model and Wavewatch (WW3) model. Both Ocean and Wave models are configured at 2.2 Km horizontal resolution covering entire Bay of Bengal region and parts of Arabian Seas. Ocean-atmosphere coupled processes over Bay of Bengal requires high- reso- lution coupled model for proper understanding of air-sea interactions and oceanic mixing. This coupled system (RCEP) can be used to carry out process-based studies and extreme events forecasting over the domain of our interest. One case study of Tropical Cyclone Fani (28th April- 2nd May 2019) is carried out using regional coupled system. Data from standalone Atmosphere and Ocean runs on our HPC are used to enhance our understanding of oceanic processes over Bay of Bengal during the passage of Tropical Cyclone. As this work is ongoing, we expect to share more results from this early study during the conference.

128 Coastal and Open Ocean processes

Study of large-scale Atmospheric convection over the tropical Indian Ocean and its association with Oceanic variables. QUICK ORAL Supriya Ovhal OSICON2021/223 Indian Institute of Tropical Meteorology

In India the summer monsoon rainfall occurs owing to large scale convection with reference to continental ITCZ. It was found that convection over tropical ocean increases with SST from 26 to 28 degree C and when SST is above 29 degree C it sharply decreases for warm pool areas of Indian and for monsoon areas of West Pacific ocean. The reduction in convection can be influenced by large scale subsidence forced by nearby or remotely generated deep convection, thus it was observed that under the influence of strong large scale rising motion convection does not decreases but increases monotonically with SST even if SST value is higher than 29.5 degree C. Since convection is related to SST gradient that helps to generate low level moisture convergence and upward vertical motion in the atmosphere. Strong wind fields like cross equatorial low level jet stream on equator ward side of the warm pool are produced due to convection initiated by SST gradient. Areas having maximum SST have low SST gradient and that result in feeble convection. Hence it is imperative to mention that the oceanic role (other than SST) could be prominent in influencing large Scale Atmospheric convection. Since warm oceanic surface somewhere or the other contributes to penetrate the heat radiation to the subsurface of the ocean and as there is no studies seen related to oceanic subsurface role in large Scale Atmospheric convection, in the present study, we are concentrating on the oceanic subsurface contribution in large Scale Atmospheric convection by considering the SST gradient, mixed layer depth (MLD), thermocline, barrier layer. The present study examines the probable role of subsurface ocean parameters in influencing convection.

129 Coastal and Open Ocean processes

Observed inter-annual variability of temperature inversions over northern Bay of Bengal: the role of Indian Ocean Dipole ORAL OSICON2021/227 Antony P. Thomas, V. Suneel, Alex M.J., V. Trinadha Rao CSIR- National Institute of Oceanography, Goa

An unprecedented collection of 12 years of monthly repeated expendable Conductiv- ity Temperature Depth (XCTD) sections across the north-western boundaries (Port Blair - Kolkata cruise transect) of the Bay of Bengal (BoB) has been used to study the evolution of Temperature Inversions (TI) and its inter-annual characteristics in relation to the large scale climatic event the Indian Ocean Dipole (IOD). The cruise transect has been divided into three regions with respect to the latitude as Port-Blair box (15oN:16oN), Middle Box (16.5oN:17.5oN), and Kolkata Box (18oN:19oN). Our data reveals that the consistent occurrence of TI occurring during November-March in all three regions irrespective of IOD events (positive or negative). However, during positive and negative IOD years, the thickness of TI layer is relatively higher when compare to neutral IOD events, in which the highest layer thickness is observed during positive IOD years. In agreement with this, the amplitude (∆T) of inversion layer also shows higher values in all three boxes during the positive IOD year. Among all three boxes, the maximum layer thickness and amplitude were observed at the Kolkata box which is very closely proximity with the mouth of Ganges-Brahmaputra delta system and gradually reduces when moving away from it as noticed in middle and Port Blair boxes. Our primary analysis indicates that the air-sea interaction processes associated with the positive IOD events alter the precipitation and hence the river run oﬀ over northern BOB causing the observed changes in TI layer characteristics. Further detailed analysis is needed to conﬁrm the results.

130 Coastal and Open Ocean processes

Characteristics of mesoscale eddies in the Bay of Bengal using a numerical model QUICK ORAL Navin Chandra, Vimlesh Pant OSICON2021/234 Centre for Atmospheric Sciences, Indian Institute of Technology Delhi, New Delhi

Oceanic e ddies are an integral part of ocean dynamics. These eddies play an important role in ocean circulation and energy transfer. Eddies enhance mixing of different oceanic properties such as temperature, salinity, and nutrients. Eddies possess about an order of magnitude higher kinetic energy than the parent current. The unique geographical and meteorological characteristics of the Bay of Bengal (BoB) make sit a natural ground of eddy activity. A number of eddies of different sizes and energy are present as an integral part of the major currents in the BoB. The formation of eddies takes place in BoB due to baroclinic instability, coastal geometry, and bathymetric features. Riverine freshwater discharge into the BoB remains high during July-October. The reversal of monsoonal winds leads to a complex surface circulation and seasonal variability in salt exchange between the BoB and Arabian Sea. In the present study, the formation and evolution of mesoscale eddies in the BoB are examined using a high resolution Regional Ocean Modelling System (ROMS). The effects of coastal currents and bathymetric features on the eddy properties are studied. Model results are validated with the available observation data. For identification and tracking of eddies, both the geometrical and dynamic al methods are utilised. The kinetic energy of cyclonic eddies (CE), anticyclonic eddies (AE) and their seasonal variability in the BoB are discussed.

131 Coastal and Open Ocean processes

An improved nearshore bathymetric data from synergistic application of active and passive satellite remote sensing and machine learning ORAL OSICON2021/237 Surisetty V. V., Arun Kumar GSD/GHCAG/EPSA, Space Applications Centre, Ahmedabad, Gujarat

The dynamic nearshore environment comprising of nearshore zone and beach continuously undergoes substantial morphological modifications due to man-made and natural events. It is most sensitive to short-term (extreme meteorological and oceanographic events) and long- term (seasonal changes in the wind and wave climate, coastal erosion) processes. Besides these, the sustainability of coastal ecosystems are threatened due to the effects of climate change, subsidence, sea-level rise etc. However, bathymetry data available from the free sources like General Bathymetric Chart of the Oceans (GEBCO) and ETOPO have limited in-situ sounding data from the shallow and nearshore waters especially near island regions and therefore inaccurate. Also, the bathymetry information available from some of the Hydrographic charts is outdated, sparse and not regularly updated. On the other hand, surveying the nearshore region (depth < 15 m) is a challenging task due to continuous wave action as a result of shoaling, which could make the surveying boat unsteady and practical difficulties with the surveying boats. There remains a global lack of nearshore bathymetry information all over the world. Therefore, the main objective of the present research is to assess the potential of satellite-derived bathymetry (SDB) in the nearshore region of few islands in the Andaman archipelago at high resolution using freely available Sentinel-2, Landsat-8 imagery (passive) and ICESat-2 LIDAR (active) data. Initially, depth data were retrieved from the ICESAT-2 raw photons automatically using an adaptive Density- based Spatial Clustering of Applications with Noise (DBSCAN) method; applied tide and refraction correction. Later, this LIDAR depth data was ingested in the SDB retrieval techniques like empirical (Stumpf’s method and Lyzenga’s method) and a non-linear Support Vector Regression (SVR) machine learning algorithms on atmospherically corrected Sentinel-2 and Landsat-8 data. The validation with independent datasets suggest that Lyzenga’s LLM method produced smoother and relatively accurate bathymetry as compared to the Stumpf’s LRM method. The LLM based SVR ML approach provides the best performance with RMSE< 0.5 m over the entire depth range (0-30 m). The SDB has a strong potential to complement the survey data in highly complex and very shallow rocky zones of islands in a more efficient, less risky and cost-effective way.

132 Coastal and Open Ocean processes

Role of ocean-atmosphere in the recent changes in cyclone activity in the north Indian Ocean ORAL OSICON2021/244 Vineet Kumar Singh1,2, M.K. Roxy1 , Medha Deshpande1 , G. Mano Kranthi1,3 , R. Emmanuel1,3 and R. Harikrishnan1,2 1Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune; 2Department of Atmospheric and Space Sciences, Savitribai Phule Pune University,Pune; 3School of Environmental and Earth Sciences, KBC North Maharashtra University, Jalgaon, Maharashtra

The north Indian Ocean is seeing significant changes in cyclone frequency and intensity in recent years with the most significant changes observed in the Arabian Sea. It is observed that there is a 48% increase in the frequency of cyclones during the period 2001–2019 as compared to the period 1982–2000. Also, in the above- mentioned period, the lifetime maximum intensity of the Arabian Sea cyclones has increased by 38% in the pre-monsoon season and 22% in the post-monsoon season. This increase in the frequency and the intensity of the cyclones in the Arabian Sea is attributed to the increase in the mid-level humidity and increase in the ocean surface and sub-surface temperatures. It is observed that in the last four decades the Arabian Sea is warming at a rapid pace as compared to the Bay of Bengal with an increase in SSTs by 1.4◦C and 1.2◦C in the pre-monsoon and the post-monsoon season respectively. The increase in the ocean surface and sub-surface temperatures in the entire north Indian Ocean is aiding the cyclones to intensify rapidly in a short time. It is observed that the rate of rapid intensification of the cyclones in the north Indian Ocean in the pre-monsoon season has increased from ∼28% to 40% in the recent period. Along with the changes in the cyclone frequency and the intensity, it is observed that the rapid warming of the north Indian Ocean has increased the cyclone-induced rainfall. These changes in the cyclone activity in the north Indian Ocean due to the changes in the ocean-atmospheric conditions pose a significant risk to the densely populated coastline of the north Indian Ocean rim countries.

133 Coastal and Open Ocean processes

Anomalous variation of sea surface temperature and air temperature in coastal North Indian Ocean in 2020: Examining the role of Covid-19 lockdowns QUICK ORAL Samar Kumar Ghose, Sthitapragya Ray, Imran Nawab, Debadatta Swain OSICON2021/246 Indian Institute of Technology Bhubaneswar

The restrictions imposed following the COVID-19 pandemic have significantly altered emissions leading to decreased air pollution levels, improvement in water quality of lakes and rivers, and possible anomalous variation in meteorological and oceanographic parameters such as air and sea surface temperature. In this study, we have attempted to examine the plausible effect of lockdowns in the coastalwaters around certain major urban centers like Mumbai, Mangalore and Chennai utilizing 10 years of Climate Data Record (CDR)data from the National Oceanic and Atmospheric Administration (NOAA).The variability of the met- ocean parameters for the post-lockdown period have been analyzed in terms of inter-annual variability and a significant anomaly is observed. It was found that a significant part of the inter-annual variability of these met-ocean parameters around the coastal urban cities (Mumbai, Mangalore and Chennai) is associated with the El NiñoSouthern Oscillation (ENSO). However, the observations after lockdown show an anomalous deviation from that trend. The year 2020 is found to be the only normal year shows nearly same anomaly of sea surface temperature (SST) and air temperature (AT) like El Niñoyears.

134 Coastal and Open Ocean processes

Intense upwelling in the southeastern Arabian Sea during the post-monsoon season ORAL OSICON2021/247 Anoopa Prasad C., Martin V. Mathew, K. N. Navaneeth, K. Jossia Joseph, R. Venkatesan Ocean Observation Systems, National Institute of Ocean Technology, Chennai

The southeastern Arabian Sea (SEAS) under the influence of monsoonal winds exhibit variability in the hydrography and circulation. The seasonal coastal current reversal and consequent upwelling make this region highly dynamic. SEAS are highly productive in the summer monsoon season due to the upwelling process. The upwelling in the SEAS during 2013-2019 is examined utilizing the Ocean Moored Buoy Network for northern Indian Ocean (OMNI) at two locations 8.2oN, 73.3oE (AD09) and 10.3oN, 72.6oE (AD10) deployed by National Institute of Ocean Tech- nology (NIOT). The OMNI buoy measures both surface met-ocean and subsurface oceanographic parameters with sensors fitted at specific levels. The analysis of vertical thermal section showed the commencement of upsloping of isotherms in March at AD09 and shoaling to a minimum in October. The minimum shoaling at AD09 was observed in 2015 which could be attributed to strong El Niñoand positive Indian Ocean Dipole. At AD10 location, upwelling starts in March and peaks in October with more pronounced shoaling than at AD09 as it is closer to the coast. Moreover, the upwelling at both locations shows distinct interannual variability. Therefore, in this study, the upwelling observed during the post-monsoon season (October-November) is explored utilizing high- resolution time-series data from moored buoys. The role of local wind stress and remote forcing from equatorial wind is also examined. In addition, the sea level anomaly from AVISO is utilized to understand the role of propagating waves and the sea level variability associated with upwelling.

135 Coastal and Open Ocean processes

Sound speed variation in the coastal waters of Kochi and signature of subsurface maxima QUICK ORAL Abdul Azeez S OSICON2021/259 CSIR-National Institute of Oceanography, Kochi

We investigated the vertical and horizontal variation of the sound speed using the Thermodynamic Equation Of Seawater - 2010 (TEOS-10) and monthly CTD observations at Cochin estuary and adjacent coastal waters (inlet to 20 km offshore) during 2018. The results showed that the sound speed varied from 1500 m/s in the Cochin inlet to 1549 m/s offshore. The seasonally changing river influx to the shelf resulted in a spatially varying salinity plume (0-35 psu) towards offshore, contributing significantly to the sound speed at near-surface waters. Such variation of saline stratification altered the sound speed up to ± 20 m/s in the Cochin inlet and adjacent coastal waters. We observed a subsurface-maximum zone of sound speed (1540 m/s) in June (monsoon season) due to the combined effect of upwelling and river discharge. This subsurface maximum formed only at the starting stage of upwelling, which disappears when the intensity of stratification decreases due to the mixing of upwelled water with the salinity plume. Correlation analysis showed that temperature was the actively prompting parameter in determining the sound speed at off Kochi waters during pre-monsoon (with a maximum of 1549 m/s recorded in April), while the combined effect of temperature and salinity influenced during monsoon and post-monsoon.

136 Coastal and Open Ocean processes

Dinoﬂagellate cyst distribution along the Karwar coast: a HAB perspective QUICK ORAL Prerana Shet1,2 , Priya M. D’Costa3 , Ravidas Naik1 , Shramik Patil1 , Mandar OSICON2021/266 Nanajkar4 , Pranay Sawant2,4 , Kaustubh Warde2 , Shivakumar Haragi2 1ESSO-National Centre for Polar and Ocean Research, Vasco-da-Gama, Goa; 2Karnatak University of Post Graduate Centre, Dharwad, Department of Marine Biology, Karwar; 3School of Earth, Ocean and Atmospheric Sciences, Goa University, Goa; 4CSIR- National Institute of Oceanography, Dona Paula, Goa

Harmful Algal Blooms (HABs) are on the rise worldwide; they have been associated with potentially severe ecological and economic consequences. Fortunately, not many incidences of HABs (commonly known as red tides) have been reported in India in the last few decades, compared to temperate and South East Asian tropical countries, and hence, were not given much attention. However, over the recent years, an increase in the number of HABs along the Indian coast has been noticed. In Karwar particularly, an important port city in Karnataka, along the west coast of India, a green tide of Noctiluca scintillans (a dinoflagellate) has been reported with increasing frequency over the years. This poster highlights findings from a preliminary study of the dinoflagellate cyst assemblages in Karwar. Sedi- ment samples were collected from 4 stations in Karwar, namely Sunkeri, Majali, Baithkol and Devgad Island, in 2018. Of these stations, only Majali and Baithkol are in the vicinity of the areas where N. scintillans blooms had been observed. The samples were transported to the laboratory, processed for dinoflagellate cysts using the reported procedure (with some modifications), and were analyzed microscop- ically. A total of 15 dinoflagellate cyst species were recorded over the 4 stations analyzed. Highest dinoflagellate cyst abundance was observed at Sunkeri (17 cysts per gram dry sediment) whereas cysts were below detectable levels at Devgad island. These abundance values are low compared to other studies in India, and elsewhere globally. Cysts of 3 HAB species (Gonyaulax spinifera, Protoceratium reticulatum and Pyrodinium bahamense) were noted. The photoautotrophic dinoflagellate cyst - Gonyaulax spinifera, exhibited a diverse distribution and predominated in most of the stations. The presence of these dinoflagellate cysts species in Karwar waters, along with the recurrent Noctiluca blooms observed, are a cause of concern. Is this going to be a recurrent feature? Considering the importance of Karwar in oceanic trade and as an emerging coastal tourism centre, it is of utmost importance to understand, through detailed studies, HAB dynamics in the coastal waters of Karwar.

137 Coastal and Open Ocean processes

A study on the seasonal variation of nearshore waves along remote islands of UT Lakshadweep, West Coast of India ORAL OSICON2021/285 D. Shyamala Varthini1, S.K. Raju2, M.V. Ramana Murthy2 1National Institute of Ocean Technology, Pallikaranai, Chennai; 2National Centre for Coastal Research, NIOT Campus, Pallikaranai, Chennai

Wave climate play crucial role in ocean wave research, navigation, understanding the nearshore coastal processes for design of coastal structures and for sustainable coastal management. This paper focus on the seasonal variations of nearshore waves along the Kadmat (latitude 11.18o to 11.25oN and longitude 72.76o to 72.79oE) and Amini islands (latitude 11.11o to 11.13oN and longitude 72.715o to 72.735oE) of Union Territory of Lakshadweep. The variability in nearshore wave climate of the Kadmat and Amini islands was studied based on 10 years of wave hindcast data from spectral wave modelling for the period from 2010 to 2020 using DHI MIKE 21 Spectral Wave Model. The Spectral wave model has been effectively used to simulate growth, decay, and transformation of wind generated waves and swells in offshore and coastal areas. Regional Model runs was established using ECMWF model winds and the offshore wave parameters were validated with ocean observations available in the Arabian sea. Nearshore wave model of fine resolution was established for Kadmat and Amini island using the offshore boundary extracted from validated regional wave model. Nearshore wave climate of islands are very complex with waves generated by local winds and also from multiple swell fields. The seasonal variability of nearshore wave parameters such as Significant Wave Height (Hs), Peak Wave Period (Tp) and

Mean wave direction (θm) was analysed and the spatial variability of wave power distribution around the islands were investigated.

138 Coastal and Open Ocean processes

Source and Fate of Anthropogenic Particles in a Transitional Environment from Southwestern India ORAL OSICON2021/289 Gokul Valsan, Amrutha K, Lino Yovan, Santhosh Prabhu, Amrish V Narayan and Anish Kumar Warrier Department of Civil Engineering, Manipal Institute of Technology, Manipal Academy of Higher Education, Manipal, Karnataka

Anthropogenic particles like Microplastics are small-sized (1 to 5 mm) and omnipresent. Recent studies on microplastics have shown its deleterious effects on the natural environment including flora and fauna. These tiny plastic particles are carried into the marine realm by rivers and winds. However, there exists gap in the literature regarding the processes that control the properties of MPs in the transitional environments - connecting the land and the sea. In this study, we present the preliminary results of the presence of MPs in coastal groundwater (n=1), beach sediments (n=11), pore water (n=2; collected using a push-point sampler from a depth of 1 metre below the surface), and sea water (n=1) from a small beach in Kota, Karnataka, southwestern India. Microplastics were extracted using standard protocols. All the samples showed the presence of MPs in different concentrations. The beach sediments had an average (±SD) abundance of 31.5 (±4.31) pieces/kg. The highest concentration of MPs (30 pieces/kg) were recovered from the high-tide line, and the lowest concentration (10 pieces/kg) was recorded at 50 metres interval from the high-tide line. Different amounts of microplastics were found in the three categories of water samples: 48 pieces/m3 in groundwater, 40 pieces/m3 in seawater, and 24-32 pieces/m3 in the porewater samples. The sediment samples were dominated by two categories of microplastics, i.e., fibres and fragments. Only fibres were found in all the water samples. The polymer composition of all the MPs will be presented at the time of the conference. The likely sources of MPs can be attributed to: fishing activities in the vicinity of the beach, washing of clothes in the region by the villagers. Further, there is every likelihood that MPs could have been washed into the beach by the incoming waves during the high tide conditions. The interesting finding in this study was the occurrence of fibrous MPs in the two porewater samples from different locations. This possibly suggests the vertical transfer of fibrous MPs in the sandy sediments. Besides, we propose that submarine groundwater discharge may also play a crucial role in transporting MPs from the continents into the oceans.

139 Coastal and Open Ocean processes

Inﬂuence of sea breeze-land breeze circulation on thermodynamic parameters over Kochi, a coastal tropical station QUICK ORAL Linsha C. L1, Hamza Varikoden2, Vishnu R1 OSICON2021/291 1Dept. of Physics, Sree Krishna College, Aﬃliated to University of Calicut, Guruvayoor, Kerala; 2Indian Institute of Tropical Meteorology, Pashan, Pune

The interactions between earth’s surface and atmosphere have a crucial role in the development of planetary boundary layer (PBL). The turbulence in the PBL causes the vertical exchange of heat, momentum, water vapors and pollutants. The structure of PBL can be determined from the thermodynamic parameters such as temperature, dew point temperature, potential temperature etc. In this present study we explored the thermodynamic variables using radiosonde data over the tropical coastal station Kochi, for a period of 31 years starting from 1989 to 2019. The data contains two observations in a day, which consists of 00 GMT and 12 GMT indicting the sea breeze and land breeze, respectively. The modulation of temperature, moisture and boundary layer fluxes over Kochi is greatly influenced by the topography and land-sea breeze circulations. To study the climatology of thermodynamic parameters over Kochi we used radiosonde data. The analysis of surface temperature showed a positive linear trend in all the season except during the sea breeze period of pre-monsoon season. The trend of temperature at higher level during sea breeze circulation was found to be decreasing during all the season except in the winter at 700 hPa. Temperature at 700hPa and 850 hPa during land breeze period is increasing in all season except during south west monsoon season. We also explored the lower tropospheric stability (LTS) based on the potential temperature at different vertical heights in order to understand the stability variations in the boundary layer. The LTS is found to be decreasing in all season except during sea breeze period of winter. The lower (higher) decreasing trend is for winter (southwest monsoon) season. There was a significant correlation between LTS and temperature. The decreasing trend of LTS may be attributed to increasing (decreasing) trend of temperature at surface level (higher) level.

140 Coastal and Open Ocean processes

Physical settings and biogeochemical response of oceanic front along the coastal waters oﬀ Mangalore, West Coast of India QUICK ORAL Vishnu Narayanan Nampoothiri S.1, Sudheesh V1,2, Kausar Fatima Bepari1, OSICON2021/294 Bikram R.1, Rasheed K.1, Anil Kumar Vijayan1, G.V.M. Gupta1 1Centre for Marine Living Resources and Ecology, Ministry of Earth Sciences, Kochi; 2Central University of Kerala, Kasargod, Kerala

An oceanic front is a narrow zone of enhanced horizontal gradients of physical, chemical and biological properties (temperature, salinity, nutrients and chlorophyll) that divides the broader area of different vertical structure. The front can be visible at oceanic surfaces as a line of separation due to change in colour, presence of debris/plastics or foam accumulation, accumulation of plankton/ marine animals. Physical settings and biogeochemical response of oceanic front were studied (∼13oN) in the coastal waters off Mangalore during the peak summer monsoon (August) of 2018 onboard ORV Sagar Kanya as part of the Marine Ecosystem Dynamics of East- ern Arabian Sea (MEDAS) programme. The variabilities in freshwater discharge and upwelling intensity were the primary causative factor for the observed salinity front over the study region. In addition to this, the low wind speed and sluggish nature of current favoured the frontal formation that has inferred from the satellite-derived wind and current data. This formation of a ’freshwater trapping’ has been observed in the inner shelf waters, that significantly influenced the nutrient biogeochemistry and associated primary production. The chlorophyll a (Chl a) concentration surged 15-20 times higher (10.12 mg/L−1) in the frontal zone compared to the non-frontal location away from it. An enrichment of silicate concentration (43 µM) led to a dominance of diatoms species such as Skeletonema costatum, Asterionellopsis sp. and Achnanthes sp. Many pollutants, plastic debris and foam-like particles were also observed in this region, affecting the biota and biogeochemistry.

141 Coastal and Open Ocean processes

Warming driven early blooming scenarios in North Eastern Arabian Sea QUICK ORAL Midhun Shah Hussain, Smitha B. R., A. A. Mohamed Hatha OSICON2021/297 Cochin University Of Science and Technology, Kochi

The North eastern Arabian Sea (NEAS) is experiencing significant warming from past decades. The warming effects are reflected in its fluid dynamics, resulting in intense stratification, and alters the community of primary producers. Blooms have a well known positive relationship with warm climate, biologically this seems to be associated with the enzyme kinetics and associated metabolic rates. The warming scenarios in NEAS are not different, which seems to have a great impact on the community dynamics of phytoplankton groups. The SST for the region has drastically changed from the past two decades. The shifts are clearly visible in the context of high chlorophyll-a and associated productions developed by mixotrophic dinoflagellates such as Noctiluca. Poor ventilation and so gaseous exchanges, and low nutrients at the upper layers of oxygen minimum zones are general observations in such systems, and are omnipresent throughout the Spring inter monsoon (SIM). Subsurface chlorophyll Maxima (SCM) is the most common biological phenomena associated with the stratification, and blooming in tropics is an emerging phenomena. There are several the- ories associated with this complimentary association. The stable water masses for proliferation, high irradiance associated with solar insolations, shallow mixed layer Depths, critical changes in density etc. are the supplementing factors. Also, influence due to global climatic features like El Niñois evident in the region. The present study focuses the early blooming scenarios, and associated stratification changes using BioArgo and remote sensing datasets of the past two decades. The biwavelet and power spectrum analysis shows complementary evidence on the development of surface blooms and pycnocline temporal settlements. The study develops a stratification index, which has biological influence, driving the productivity patterns in the system. The projection of the index on RCP 4.5 and 8.5 seems very crucial in the analysis. The present work gives insights on one of the critical impact of warming on the marine ecosystems.

142 Coastal and Open Ocean processes

Coastal Risk Assessment of Alappuzha district in Kerala, India QUICK ORAL Unnikrishnan K1,2, M. K. Roxy1 OSICON2021/310 1Indian Institute of Tropical Meteorology (IITM), Pune, India; 2Amity Institute of Environmental Science, Amity University, Noida, U.P.

Nearly one-third of India’s population lives on or near the shore, and is reliant on its resources. Coastal regions have acquired prominence due to a variety of factors, including high ecological production, dense population, industrial friendliness, waste disposal, tourism, transit, military strategic planning, and so on. These coasts are always in a state of ﬂux, striving to change, and nature is continually working to keep the balance. Along the Indian coast, shoreline erosion, storm surges, and catastrophic events have resulted in signiﬁcant human deaths, environmental damage, and property loss. As a result, methodologies for assessing coastal vulnerability have been developed in order to detect and manage susceptible locations along the coast. In this study, We carry out a risk assessment to the Alappuzha coast in Kerala using the coastal vulnerability index methodology. Vulnerability assessment is the process of identifying a problem, quantifying it, and calculating the risk rate in order to establish development plans to minimize risk and vulnerabilities. For Alappuzha coast, we identify the compound risks due to climatic changes due to rising sea level, increasing storm surges due to an increasing number of cyclones in the Arabian Sea, and an increase in the amount of heavy rain events.

143 Coastal and Open Ocean processes

Inﬂuence of low Saline Pool on the Upper Layer Dynamics of the South Eastern Arabian Sea ORAL OSICON2021/313 Muhammad Shafeeque, Vishnu Narayanan Nampoothiri S., Smitha B. R., Kusum Komal Karati, Rasheed K., Asha Devi C.R., Hashim Manjebrayakath Centre for Marine Living Resources and Ecology, Ministry of Earth Sciences, Kochi

The South Eastern Arabian Sea (SEAS) is unique and one of the most productive regions in the Indian Ocean where the ecosystem processes are regulated mainly by the reversing winds and currents. The present study explores the influence of an excess summer monsoon rainfall on the upper layer hydrodynamics and its biological response using both observational and satellite data. The in-situ data were collected onboard FORV Sagar Sampada during September 2020. An unusual low saline pool was noticed in the shelf region of SEAS (between 10–14oN) with weak surface currents (<0.1 m/s) and winds (<3 m/s). The hydrographical data along with wind and rainfall revealed the presence of a cyclonic eddy during the observation that also controls the flow of low saline pool. This unusual occurrence was found to suppress the coastal upwelling and its impact was evident in the bio-production of the region. However, active upwelling was observed in the southern transects (off Cape and Kollam) associated with comparatively strong wind (>6 m/s), surface current (0.2 m/s) and weak rainfall (<13 mm/day). The persistence of low saline pool in the off-shelf is unusual in this region and this was co-occurred with high temperature and salinity gradients in the upper 20 m. The strong stratification within a dynamic season, are favourable for the buoyant phytoplankton to flourish in the surface, resulting enhanced chlorophyll-a concentration. In contrast, the low saline pool had resulted in decreased zooplankton biomass in the upper layer. The observations indicate that any variability in the atmospheric forcing (rainfall/ wind) may lead to change in the upper layer hydrodynamics and hence impact the ecosystems processes. The present study tries to address the role of atmospheric forcing on upper layer hydrodynamics in the SEAS and thereby changes in the regional ecosystem.

144 Coastal and Open Ocean processes

Modulation of boundary layer parameters in association with tropical cyclones over the Bay of Bengal QUICK ORAL Arjun S. Nair1,2, Hamza Varikoden1, Vishnu R2 OSICON2021/314 1Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune; 2Dept. of Physics, Sree Krishna College, University of Calicut, Guruvayoor, Kerala

In this paper we are analyzing the impact of tropical cyclones (TCs) over the Bay Of Bengal (BoB) on surface boundary layer parameters during the pre monsoon, monsoon and post monsoon seasons. We utilised the track of tropical cyclones over BoB from Joint Typhoon Warning Centre Best Track data and boundary layer parameters are obtained from tropflux data products. The climatology of momentum flux (MF), sensible heat flux (SHF), latent heat flux (LHF), wind speed (WS), atmospheric boundary layer height (ABLH), outgoing longwave radiation (OLR) and rainfall have been studied during all the three seasons by considering the base period as 1979-2018. By tracking locations of TCs occured in BoB from 1979-2018 in different monsoon seasons, we could find that more tropical cyclones have occurred in the post monsoon season compared to the pre monsoon season, and the least is in the southwest monsoon season. We had also identified one fact that during pre monsoon, the TCs occurred mainly in central BoB while in the southwest monsoon period, it was along the east coast of India. However, during the post monsoon, TCs are located all over the BoB and widely scattered with high frequency. For getting the impact of TCs in surface boundary layer parameters we are taking anomalies of each parameter by analyzing 5 days before, during and 5 days after the cyclone in order to explore the boundary layer conditions before, during and after the TCs. We found that the surface boundary layer parameters have profound differences during the TC periods while comparing with before and after the TC phases. Moreover, seasonal differences were also noticed in these parameters. Similar observations were made for the OLR, rainfall and Boundary layer heights.

145 Coastal and Open Ocean processes

Spatio-temporal variations in the current pattern associated with Oceanic South Eastern Arabian Sea ORAL OSICON2021/326 Arun V S, Smitha B. R. Centre for Marine Living Resources and Ecology, Ministry of Earth Sciences, Kochi

The South Eastern Arabian Sea (SEAS) coastal region is well explored in both physical and biological aspects with a large amount of accessible in situ data, but the physical-biological interactions of the Open SEAS (O-SEAS) region (the region including the Lakshadweep Island ecosystem) remains less explored. The O-SEAS is a unique area that envelops a part of the Chagos- lakkadive archipelago and experiences reversal in upper layer dynamics seasonally. This study brings out a detailed understanding of the dynamics in the current pattern and forcing mechanism in the O-SEAS using a suit of observational and model outputs (ADCP mooring, Buoy, and satellite data). The currents were also addressed using the HYCOM model data sets, wind stress and curl derived from the ASCAT were used to explain the supporting atmospheric forcing. The multi-year current data in the coastal (near to the island) and the oceanic region were subjected to wavelet (morlet) analysis to explain the multi-frequency signals. The wind forcings near the island and offshore regions were found to be similar. The coastal currents showed high-frequency variations compared to the low-frequency variations observed in the offshore regions. Also the wind and current were out of phase indicating the presence of remote forcing (Rossby waves) in the region. The Rossby waves propagating from the SEAS coastal belt along 6-12◦N is having a major role in regulating the upper- layer process in the region in both summer and winter. While, the coastal dynamics are influenced by small frequency variations due to the shelf currents, tidal effects, etc. The influence of these small-scale variations however was not reflected in the HYCOM derived data sets, and the present attempt thus put forward the role of small-scale features and the island mass in regulating the regional ecosystem dynamics.

146 Coastal and Open Ocean processes

Climatological Characteristics of Atmospheric Parameters during the Rapid Intensiﬁcation of Tropical Cyclones over the North Indian Ocean ORAL OSICON2021/328 Thatiparthi K1, Ambily Thankachan1, Reshma M. S1, K. S. Singh1,2, Subbareddy Bonthu3, Prasad K. Bhaskaran4 1 Department of Mathematics, Vellore Institute of Technology, Vellore; 2 Centre for Disaster Mitigation & Management, Vellore Institute of Technology, Vellore; 3 National Centre for Sustainable Coastal Management, Ministry of Environment, Forest and Climate Change, Anna University Campus, Chennai; 4 Department of Ocean Engineering & Naval Architecture, Indian Institute of Technology Kharagpur

Rapid Intensification (RI) of tropical cyclones (TC) over the North Indian Ocean (NIO) causes more destruction of lives and property of coastal communities along the coastal regions of the Bay of Bengal (BoB) and Arabian Sea (AS). However, in the recent decade, the frequency of the RI of tropical cyclones trend is gradually increasing in the BoB and AS, and is a challenging task for the forecaster to predict the cyclone track, intensity, and landfall location of TC using numerical weather prediction models. It is a prerequisite to analyze the characteristics of atmospheric parameters such as vertical wind shear, relative humidity, air temperature, and radiative fluxes during the RI of tropical cyclones over a period of recent 30 years. The present study focuses on the investigation of the past 30 years TCs made landfall over the Indian coast to understand the climatological characteristics of atmospheric parameters such as vertical wind shear, relative humidity, air temperature, precipitation, and radiative fluxes. The best track of TCs data obtained from the India Meteorological Department (IMD) and estimated the formation of TCs about 109 and 46 over the BoB and the AS respectively during 1982-2020. It also observed that the Ex- tremely Severe Cyclonic Strom and Super Cyclonic Storms are about 24 and 4 over the BoB and about 9 and 2 over the AS respectively. The TCs formed over the BoB and AS are made maximum landfall on the coast of Andhra Pradesh and Odisha along the east and on the coast of Gujarat along the west of India. The RI of TC has been identified from the best track data of IMD by considering the maximum surface wind speed of 30 knots (15.4 m/s) within 24 h and found the increasing trend of vertical wind shear, relative humidity, and precipitation in the recent decade. It also observed that the phase reversal of intensity of TCs formed over the BoB and AS in the pre-monsoon and post-monsoon season of years. This study also revealed that the frequency of high-intensity TCs over the AS is compared to the BoB in recent years (2018–2020). This study will be further extended with spatial and temporal characteristics of atmospheric parameters and the triggering conditions for RI of TCs over the BoB and AS of the North Indian Ocean.

147 Coastal and Open Ocean processes

Performance of Atmospheric-Ocean Coupled Model in the prediction of Rapid intensiﬁcation of Super Cyclonic Storm Amphan over the North Indian Ocean QUICK ORAL Reshma M S1, Ambily Thankachan1, Thatiparthi K1, K S Singh1,2, Subbareddy OSICON2021/329 Bonthu3, Prasad K. Bhaskaran4 1 Department of Mathematics, Vellore Institute of Technology, Vellore; 2 Centre for Disaster Mitigation & Management, Vellore Institute of Technology, Vellore; 3 National Centre for Sustainable Coastal Management, Ministry of Environment, Forest and Climate Change, Anna University Campus, Chennai; 4 Department of Ocean Engineering & Naval Architecture, Indian Institute of Technology Kharagpur

Recently, the Super Cyclone Amphan considered as one of the most powerful and catastrophic tropical cyclones (TC) over the Bay of Bengal and underwent a rapid intensification, caused widespread damage to the lives and property of the coastal communities along the coast of the Odisha, West Bengal, and Bangladesh during May 2020. The timely and accurate prediction of rapid intensification (RI; wind speed changes more than 30 knots in 24 hours) of TC is one of the challenging tasks for the researcher community. The present study performed a coupled atmospheric– ocean [WRF and WRF–OML (Ocean Mixed Layer)] model for the prediction of rapid intensification of super cyclonic storm Amphan over the Bay of Bengal. The initial condition and lateral boundary conditions for the model is derived from the National Centers for Environmental Prediction (NCEP) GFS analysis at forecasted dates, has a horizontal resolution of 0.25◦x 0.25◦. Similarly, the profile data of oceanic parameters such as temperature, salinity, and density which are obtained from the World Ocean Atlas 2018 and Argo data are provided as initial conditions for the OML model. The model simulated results of finer resolution at 3 km, 4 km, 5 km and 9 km is compared with the India Meteorological Department (IMD) best-fit datasets and rainfall. The results of the WRF-OML modeling system showed the prediction of track, intensity, and rainfall of the storm is better compared to the control run of the WRF model. This also highlighted the high-resolution WRF- OML coupled model is very important in the forecast of intense tropical cyclones for the prediction of rapid intensification. The spatial and temporal variation of the simulated temperature, salinity, and current also discussed in this study. This study will be further extended by analyzing the radiative fluxes and their role in the rapid intensification during the life cycle of Amphan cyclone.

148 Coastal and Open Ocean processes

Wind-Wave Relationship Considering Local and Remote Wave Eﬀects from Moored Buoy Measurements in the South-East Arabian Sea ORAL OSICON2021/334 M. Kalyani, K. Jossia Joseph, R. Venkatesan Ocean Observations Systems Group, National Institute of Ocean Technology, Chennai

Wind and wave characteristics are site specific in nature. They vary seasonally with varying sea-states. The available wind-wave relationships are primarily based on empirical relations for equilibrium and neutral conditions. These are generally linear relations with constant coefficient which do not account for the varying wind conditions such as wind intensity and direction. Moreover, wave characteristics at a specific location include the effects of local wind waves (wind seas) as well as remote forcing (swells). The coefficients applicable for one location may not describe the characteristics satisfactorily at another location and hence may not be applicable. The linear relations may not suffice during high intensity events such as cyclones and may need to resort to nonlinear relationships for better description and assessment. Though the frequency and the intensity of cyclones is less in the Arabian Sea when compared to that of the Bay of Bengal, the climate change effects are altering the scenario rapidly. This speaks of the dire need for establishing a better relationship between winds and waves, especially wherever the observations are available. Observed data of both winds and waves are needed to formulate effective empirical relations, alleviating above mentioned inadequacies. The dynamic nature of the relationship under varying seasons, demands at least yearlong measurements at any location. Long-term measurements can bring out the inter-annual variation. In situ observations with high temporal resolution are necessary to capture the intricacies of the dynamics. Considering the above fact, the continuous high resolution wind and wave measurements obtained from OMNI buoy of ESSO-National Institute of Ocean Technol- ogy on the southeast Arabian sea in deep waters have been utilized to establish the wind-wave relationship. The South-east Arabian Sea is characterized by swells orig- inating from Southern Indian Ocean. It is also under the influence of seasonal wind reversal and Indian monsoons. Seasonal variability of wind intensity, and direction, local and remote effects (seas & swells) of waves, as well as nonlinear variation during cyclones are taken into account. These established empirical relations can be utilized to obtain oceanic parameters (wave) from meteorological observations alone (wind) with reasonably good accuracy at that site.

149 Coastal and Open Ocean processes

Phenology of Coastal Upwelling in the South Eastern Arabian Sea ORAL OSICON2021/335 Shirin Jadhav, Muhammad Shafeeque, Smitha B. R. Centre for Marine Living Resources and Ecology, Ministry of Earth Sciences, Kochi

The marine ecosystem responses in the South Eastern Arabian Sea (SEAS) during summer monsoon are regulated mainly by the periodic cycle (phenology) of coastal upwelling. This phenology of upwelling in the SEAS along the west coast of India from Cape to Ratnagiri region (7–17oN) is examined using daily, weekly, monthly, and seasonal time series of sea surface temperature (SST) data. Seventeen years of satellite-derived SST for the summer season (2003–2019) have been used with the methodology of offshore-onshore SST gradient named Local temperature Anomaly (LTA). Northward propagation of upwelling is seen with the onset of monsoon from India’s southern tip to the Goa region, north of Goa recorded week, or no upwelling signature during the study period. Referring to the past studies and LTA calculations, we have subdivided the region into four latitudinal zones: lower (LZ- 7o to 9oN), middle (MZ- 9o to 13oN), upper (UZ- 13o to 17oN), and modified upper (MUZ- 13o to 15oN) zone. The upwelling starts from mid-May along LZ with a maximum upwelling strength in July, followed by MZ in August, and MUZ during September. Seasonal climatology shows the magnitude of upwelling in LZ is more than double that of other zones. While, the magnitude of upwelling for MZ and MUZ is almost the same, the offshore extension for MUZ is limited to the coast. The satellite-derived upwelling index was further correlated with in-situ observations on the shift in isolines of 23oC (D23) and found significant relation between the two. The trend of upwelling is negative due to the extreme climatic events like El-Niñoand Indian Ocean Dipole (IOD) which are very frequent in recent years. A noteworthy fall in the upwelling strength for all zones was remarked coinciding with the extreme events which also resulted in decreased productivity. Eliminating the signals due to extreme years, results in a significant positive upwelling trend for the lower zone, insignificant for the middle, and negative for the upper zone. The present study defines and details the phenology of SEAS coastal upwelling that determine the onset-offset timing, strength, peak, relaxation phases, duration etc. and the teleconnections.

150 Coastal and Open Ocean processes

Inter comparison of underwater acoustic properties derived from diﬀerent reanalysed products and in situ observations in the South Eastern Arabian Sea ORAL OSICON2021/338 Maheswaran P A1, Harikrishnan M1, Satheeshkumar S1, Varkichen Joy2 1 Naval Physical Oceanographic Laboratory, Ministry of Defense, Kochi; 2 M/s Kayens Tech, Pvt LTD, Kochi, Kerala

An accurate depiction of ocean environment determine the performance of the acoustic sensors employed during the Anti–Submarine Warfare scenario. Under water acoustic waves propagate from one location to another is determined by many factors, primarily by the sound speed profile (SSP) up to the bottom. One way to derive the SSP is from the in situ profiles such as CTD/XBT. This method is not always tactically feasible and it gives vertical profiles at one location and producing a very limited picture of the regional ocean structure. Another method is to estimate the ocean conditions using numerical models with proper data assimilation techniques. At present, a handful number of commonly used reanalysed ocean data products with very high spatiotemporal resolution are available. However the efficacy of these ocean products and its usefulness to describe the underwater acoustic properties of the medium are not yet studied. The present study attempts an inter comparison of ocean environment in different ocean reanalyses such as NCEP- GODAS, INCOIS-GODAS, ECMWF-ORAS5, ECC02 Cube 92 model, CMEMS- Global Analysis Forecast PHY 001 024 with reference to the in situ data. For the inter comparison of these products, INS Sagardhwani of DRDO-NPOL have carried out dedicated monthly data collection program during 2016–17. In this period, 560 CTD profiles were archived and prepared as the baseline data for inter comparison. The evolution of various oceanographic features and their discrepancies over the different data sets were analyzed. Present study also assessed the vertical structure of temperature, salinity and sound speed in different reanalyzes over the west coast of India. Biases/differences on sound speed profiles and the corresponding acoustic characteristics such as cut off frequency, Sonic Layer Depth, gradients of sound speed in the sonic layer and below layer were described in detail in this paper. To understand the significance of the accurate description of sound speed profile on acoustic propagation, transmission loss modelling (Kraken RQ) has been employed for all the in situ as well as the respective profiles in the reanalyzed products. The performance of reanalyses with respect to the observation were evaluated using the statistical scores such as root mean square error (RMSE) and pattern correlation for Sea Surface Temperature, Sea Surface Salinity, Sonic layer depth for the region.

151 Coastal and Open Ocean processes

Thermohaline and acoustic characteristics of the Srilanka Dome during July 2019 ORAL OSICON2021/339 Dominic Ricky Fernandez, Raju R. P., Varkichan Joy, Niji T. Y. Naval Physical Oceanographic Laboratory, Ministry of Defense, Kochi

The thermohaline characteristics of the Srilanka dome was observed during the SagarMaitri 2019 expedition. The main aim of the program was to study the physical characteristics of the observed eddy such as its effect of the thermal structure and acoustic propagation across the eddy. During July 2019 a cyclonic eddy was observed along 10oN from 83E-87oE. Utilizing direct Conductivity Temperature Depth (CTD) sensors and remotely sensed data of sea level anomaly. The SLA data showed that this cyclonic eddy (CE) formed near the Srilanka coast. Surface winds and currents indicated that the CE was generated due to wind stress along the southern tip of Srilanka that occurred a poleward flow located close to the coast. During its growing phase, the eddy extended from the surface to 250 m depth and mixed the water column in the first ∼100 m. The eddy is estimated to transport relatively warm,salty, waters associated with the Arabian Sea High Salinity Water Mass. The cyclonic eddy also exhibited relatively higher chlorophyll a concentrations at the sea surface than its surroundings. The acoustic propagation across the cyclonic eddy was analyzed using a parabolic equation and the effect of the dome on range dependent acoustic propagation was studied.

152 Coastal and Open Ocean processes

Characteristics of Diurnal Sea Surface Temperature Variability in the North Indian Ocean and its Implications to Air-Sea ﬂuxes ORAL OSICON2021/351 M. V. Martin, K. N. Navaneeth, C. Anoopa Prasad, K. Jossia Joseph, R. Venkatesan Ocean Observation Systems, National Institute of Ocean Technology (NIOT), Chennai

Five years of hourly moored buoy observations based on twelve moored buoys in the north Indian Ocean is used to analyse the diurnal variability Sea Surface Tem- perature (SST) and relevant meteorological parameters and air-sea flux terms. The diurnal SST variability is defined as the difference in maximum and minimum values of SST during a 24 hour period starting from 5:30 am in local solar apparent time. Besides, the vertical extent of diurnal SST variability at depths 0.5, 1, 5 and 10 m (foundation SST) are analyzed. Moored buoy locations in both Arabian Sea and the Bay of Bengal exhibited pronounced diurnal variability in SST during pre-monsoon and post-monsoon transition periods. The diurnal variability is relatively high (low) in the northern Bay of Bengal (northern Arabian Sea). Weak wind events (wind speed less than 0.5 meter per second).

153 Coastal and Open Ocean processes

On the Variability of Arabian Sea Mixing and its Energetics ORAL OSICON2021/352 Singh Shikha 1,2, Vinu Valsala1, A G Prajeesh1,2, Sridhar Balasubramanian2,3 1 Indian Institute of Tropical Meteorology, Pune; 2 Interdisciplinary Programme (IDP) in Climate Studies, Indian Institute of Technology, Mumbai; 3 Department of Mechanical Engineering, Indian Institute of Technology, Mumbai

The mechanism of interannual variability of Arabian Sea (AS) mixing is studied by examining its energetics from 60 years of model output (1950–2009) generated using an ocean general circulation model. The model results are compared with ocean reanalysis data for the same period. Both model and reanalysis data show consistent patterns of interannual variability of AS mixing. It is observed that the dominant mode of interannual variability has a basin-wide structure with monotonic sign throughout the basin, albeit with a higher intensity in the central and southeast regions of the AS. The variability is primarily controlled by El Niño- Southern Oscillation with shallower (deeper) mixed layer during El Niño(La Niña).During a typical La Niñayear, the wind stress forcing, heat fluxes, and evaporation minus precipitation together cause deepening of mixed layer depth (MLD) in AS. This MLD variability has the strongest signal in winter months (i.e., December to February [DJF]). Further, the resolved mixing energetics suggest that the dominant forcing of MLD variability changes with seasons and has a regional preference. Buoyancy production of turbulent kinetic energy (TKE) governs the mixing and associated MLD variability in central AS during September to November (SON) and in northeast AS during DJF. Both buoyancy and mechanical production of TKE govern MLD variability in southwest to central AS from June to August and southeast AS in SON. Thus, the study highlights basin-wide structure of interannual variability of AS mixing along with its controlling mechanisms with strong regional dependency owing to the contrasting nature of forcing prevailing over various parts of the AS.

154 Marine Geology and Geophysics (MGG)

Session Chairman

Dr. K. A. Kamesh Raju National Centre for Polar and Ocean Research (NCPOR), Goa

155 Marine Geology and Geophysics (MGG)

Invited Talk

INVITED TALK: Outstanding Research Questions in Indian Ocean Tectonics

Prof. Jyotiranjan S. Ray

National Centre for Earth Science Studies (NCESS), Thiruvananthapuram, Kerala Marine Geology and Geophysics

Boron isotope study of foraminiferal carbonate from the Arabian Sea ORAL OSICON2021/39 Anjana Gireesh S1, Mohd. Tarique2, Waliur Rahaman2 1Department of Marine Geology and Geophysics, Cochin University of Science and Technology, Kochi; 2 National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Goa

CO2 concentration in the atmosphere has increased from 280 ppm during pre - industrial time (∼1850) to 415 ppm at present. Modern oceans are becoming more acidic due to absorption of the anthropogenic CO2. This has adverse eﬀect on marine organisms and their ecosystem. Instrumental records of ocean pH are available only for the past few decades. Therefore, we need to rely on proxy-based reconstructions. In this regard, boron isotopic composition (δ11B) of foraminifera has been utilised to reconstruct paleo-pH of oceans and pCO2 of the atmosphere. However, due to limited number of proxy records, the global and regional inﬂuence of CO2 on decadal to millennial-scale is not well understood. Further, knowledge on the relativecontribution of individual forcing factors to the overall pH variability needs to be better constrained. In this study, we have compiled the published boron isotope derived pH or pCO2 records generated using planktic foraminifera. Further, 11 (δ B)-pCO2 records has been compared with alkenones-pCO2 records for the past 50 million years, which shows that there were events / time in the past when the

CO2 was much higher than the present. Further, we have separated boron from the matrix using ion exchange column chromatography for measuring the boron isotope ratio. We have also measured the boron isotope ratio of the certiﬁed reference materials, ERM AE121. The average (δ11B) value of ERM AE121 is 19.66 ± 0.10(n=12), which is similar to the reported values within the uncertainty. Additionally, to ensure that the column chemistry method is working for natural biogenic carbonates, the boron isotope ratio of the foraminifera, G. ruber was also measured. All the measurements of the certiﬁed reference materials and natural carbonates shows that our measurements are well within the reported range.

157 Marine Geology and Geophysics

Intensiﬁcation of Oyashio Current as ‘Possible Cause’ for Reduction in the Western Paciﬁc Warm Pool during last 1 My: Planktic foraminiferal evidences from the Sulu Sea QUICK ORAL Vikram Pratap Singh1, Ashutosh K. Singh2, Devesh K. Sinha2 OSICON2021/50 1Department of Geology, IGNTU, Amarkantak; 2Department of Geology, University of Delhi

The Sulu Sea is an important pericratonic basin in the proximity of the South China Sea and western Pacific Ocean, which receives water from both the water bodies through several shallow straits. The pelagic sediments from Sulu Sea are excellent proxies to decipher the paleoceanographic history of the western Pacific Ocean. In the present study, we studied planktic foraminifera from 240 samples of the ODP Hole 769B in the Sulu Sea to study the paleoceanography in the western Pacific region for the last 1 million year. The census count data of planktic foraminiferal species Pulleniatina obliquiloculata, Globigerinoides ruber, Neogloboquadrina pachy- derma (sin.), Globigerina quinqueloba and Globorotalia inflata was correlated with the δ18O data of Gs. ruber. The comparative study led us to discovery of five events of lowering in the population of Pu. obliquiloculata which were quite well correlated with the positive excursion in the δ18O values. These events were accompanied with high relative abundance of Gs. ruber, which is a warm water, mixed layer dweller. These events seem to indicate the development of cold conditions in the western Pacific region due to intensification of the cold Oyashio Current. We have named the events as: OI-1(0.04-0.04 My); OI-2 (0.16-0.13 My); OI-3 (0.28-0.24 My); OI-4 (0.48-0.44 My) and OI-5 (0.78-0.65 My). Due to the intensification and migration of Oyashio Current equatorward, the Western Pacific Warm Pool might have reduced in size. which would have restricted the influx of warm water in the Sulu Sea. This could have led to the reduction in the SST. The advecting waters from the Oyashio Current must have increased the nutrient supply as indicated by the increase in the eutrophic species during these periods.

158 Marine Geology and Geophysics

Mg/Ca of marine carbonates as a paleotemperature proxy: A case study of the southeastern Arabian Sea for the past 40Kyrs QUICK ORAL Tejeswar Dash, Manish Tiwari OSICON2021/81 National Centre for Polar and Ocean Research, Vasco-da-Gama, Goa

The Arabian Sea is a landlocked basin from three sides resulting in complex hydrography. The basin experiences strong monsoon-induced circulation changes during Summer and Winter. SST also shows a huge variability due to upwelling during monsoon season. The annual average variability of the SST in the Arabian Sea is 4-5 degrees Celsius. Historically, paleoceanographic time series reconstructions of the South Asian monsoon have taken advantage of signals associated with summer monsoon induced upwelling in the western Arabian Sea, such as the percentage and/or isotopic composition of speciﬁc planktonic foraminifera within the upwelling regions. In contrast, the southeastern Arabian Sea (SEAS) received little attention especially reagrding water column temperature reconstruction. Thus, there is a need for quantiﬁcation of past climate change from the SEAS. A sediment core was recovered during ORV Sagar Kanya cruise SK-274 from SEAS near thesouthern tip of India (SK 274-1G). It is used for reconstructing the past SST from the SEAS. The radiocarbon age model shows that it covers approximately a period of 40,000years BP. In our study, Mg/Ca-derived temperatures in MIS 3 are slightly higher than the calculated modern-day temperature of G. ruber, which is fascinating and leads us to further investigate processes occurring in his region. The SST data from this core will be compared with earlier studies to get a holistic view of SST evolution in the Arabian Sea since the last glacial period. It will be further compared with SAM and ENSO indices to explore the global linkages.

159 Marine Geology and Geophysics

Southern Ocean link to Indian Monsoon Variability during the last Glacial Period QUICK ORAL Vikash Kumar, Manish Tiwari OSICON2021/99 National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Goa

Climate variability during the last glacial period was dominated by series of abrupt changes of opposite nature at the two poles and their adjoining regions. While the nature of this bi-polar seesaw is still debated, little is known about its spread into the mid-latitude and tropical regions. In this work we have carried out quantitative climate reconstruction from the sub-tropical front region in the Indian sector of the Southern Ocean using trace analysis of sediment core ABPS-4 since past 70 kilo years. The Mg/Ca reconstructed record of surface temperature shows distinct climatic regimes during the period. Notable features of the record includes a warm and highly variable SST during MIS-3, coldest surface conditions during LGM (18.5 ky BP), an Antarctic-like gradual deglacial rise, and a negative Holocene SST trend. Although, a substantial portion of the Southern mid-latitude variability appears to be linked to the bipolar seesaw, signiﬁcant regional scale independent variabilities were present too. Using the reconstructed SST data and an independently available paleo model data, we show that the Southern Ocean climate in the Indian sector controlled sub-orbital variability of Indian Summer Monsoon during the last glacial period.

160 Marine Geology and Geophysics

South Asian Summer Monsoon variability during the Mid-Piacenzian Warm Period QUICK ORAL Sarathchandraprasad T , Manish Tiwari OSICON2021/100 National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Vasco-da- Gama, Goa

Predicting the response of the South Asian Summer Monsoon (SASM) to the present global warming is an active and important area of research. Considering this, studying past periods when the COo concentration and warmth are similar to that expected in near future can be helpful. The most recent such period occurred around 3 million years ago and is known as the Mid-Piacenzian Warm Period (mPWP). Multiple proxies of terrigenous input (Ti), clasticity (Ti/Ca), chemical weathering (K/Al, Mg/Al), and productivity (Ba/Al, Caexcess) in sediment collected during IODP Expedition 355 (Site U1456) were used to reconstruct SASM variability spanning the mid to late Piacenzian (3.3–2.6 Ma). This study finds that the SASM precipitation intensified during warm episodes (interglacials) and weakened during the colder ones (glacials) of the mPWP and beyond in close correspondence with the global climate. Interestingly, after the end of the warm period (mPWP), the SASM shifted to a higher mean state at 2.95 Ma. It could be because of the tecton- ically induced reorganization of the Indonesian Throughflow (ITF), which enhanced the cross-equatorial pressure gradient by changing the source of water coming to the southern equatorial Indian Ocean. During the intensification of the northern hemisphere glaciation after 2.95 Ma, the SASM shows a long- term decline over and above the glacial-interglacial variability. Earth’s orbital parameters, especially eccentricity, appear to govern the SASM variations during the study period.

161 Marine Geology and Geophysics

Denitriﬁcation and hydrographic variability during Mid-Pleistocene Transition: Results from IODP Expedition 355 QUICK ORAL Shubham Tripathi, Manish Tiwari OSICON2021/104 National Centre for Polar & Ocean Research, Ministry of Earth Sciences, Vasco-da-Gama, Goa

Mid Pleistocene Transition (MPT) is the recent transition (∼ 900 ka, thousand years ago) in the earth’s history when the dominant glacial-interglacial cyclicity shifted from 41 kyr to quasi 100 kyr. The cause of MPT from 41 kyr to 100 kyr glacial-interglacial periodicities and more intense glaciation after 900 kyr is not well understood. Various studies on MPT exist from Atlantic and Pacific regions using proxy and models. In contrast, high-resolution studies focusing on MPT from the Arabian Sea are lacking. The present work is the first of its kind quantifying the oceanic temperature (based on Mg/Ca ratio of planktic foraminifera), and oceanic salinity during MPT from the Arabian Sea. We also reconstructed the high-resolution denitrification and productivity variability during MPT related to climatic and monsoonal evolution during the period of study. The productivity and denitrification were higher during the warmer periods of the MPT accompanied by weaker ventilation. A comparison of our record with that from the western Ara- bian Sea yields a synchronous variability between the two regions during the MPT. Modern observations show that low temperature and high salinity occur during the monsoon at the study site. We find high salinity during the warmer periods (MIS 27, 25, 21, and 19) implying intense monsoon. The wavelet transform and Redfit analysis shows the influence of external and internal forcings. It showed the influence of precession and insolation at 15oS (I15o) on the South Asian Monsoon (SAsM). Our newly generated record spanning 540 kyr provides evidence that SAsM vari- o 18 ability is driven by precession. We saw a good match of I15 with δ Osac , which corroborates earlier studies of upper-ocean stratification from the Southern Indian Ocean. It supports a robust sensitivity to warming in the Southern Hemisphere. The continuous wavelet transform reveals that the ∼24 kyr periodicity dominates from 0.97 Ma to 0.85 Ma. The same periodicity is observed during ∼0.79 Ma to ∼0.77 Ma.

162 Marine Geology and Geophysics

Importance of geomorphological characteristics in determining location suitability for setting up desalination plants ORAL OSICON2021/204 A. Baskaran, J. Vinoth Kumar, S. Karthikeyan, M. Prabhakaran, P. Chandramohan Indomer Coastal Hydraulics, Chennai

Increasing demand for water in urban areas and agricultural zones in dry and semi- dry coastal regions has urged planners and regulators to look for alternative renew- able water sources. Seawater Reverse Osmosis Desalination plants have become an essential alternative source for the production of freshwater in such regions. This paper focuses on the strategy to investigate and arrive a most suitable corridor and location while planning the seawater intake scheme. The type of design and construction methodology of the intake scheme play a major role in cost effective operation and preservation of marine ecology. The determination of suitable corridor is arrived based on the geomorphology of the seabed identified on conducting the shallow seismic survey and the side scan survey. While the shallow seismic survey enables to identify the presence of buried rocks if any, the side scan survey gives the picture on any obstruction along the selected corridor. While most of the stretches in west coast are present with bed rocks, the east coast shows dominantly with sediments. For sandy bottom, a trench is usually made, pipeline is laid and backfilled. In contrast, if the seabed is rocky then it necessitates to look for trestle type intakes. The authors had done geomorphological investigations along east and west coasts of India for designing more than 20 plants and discuss variable options in planning the suitability of locating the intakes and in turn the desalination plants. The case studies of one at east coast on sandy bed and another at west coast over the rocky terrain are also discussed in the paper.

163 Marine Geology and Geophysics

Quantiﬁcation of basin-level air-sea carbon dioxide exchange across the Mid Pleistocene Transition QUICK ORAL I. V. Satya Chanakya, Sambuddha Misra OSICON2021/216 Indian Institute of Science, Bangalore

The mid-Pleistocene transition (MPT), from 1250 to 700 kyr ago, marks a fundamental shift in Earth’s climate, when the amplitude and the periodicity glacialinter glacial cycles increased from obliquity-forcing driven 41 kyr cycles to the considerably weaker eccentricity-forcing driven 100 kyr cycles. A striking feature of the Pleist ocene glacial-inter glacial cycles is the transition in periodicity between 950 to 860 kyr, centered at ∼900 kyr on marine isotope stage 23, when the first appearance of 100 kyr glacialinter glacial cycle is recorded. A long-term drop in atmosph eric CO2 concentration (pCO2), brought about by changes in deep-ocean ventilation, is considered to be the possible driving mechanism of the MPT. However, the role of atmospheric pCO2 during the MPT [6] remains enigmatic in absence of a robust CO2 record . I will create the first high -resolution record of atmospheric and deep-ocean CO2 concentrations across the MPT by analyzing the boron isotope ratio of planktonic and benthic foraminifera from a global selection of Deep Ocean drill sites. This effort will extend our knowledge of atmospheric pCO2 beyond the temporal expanse of Antarctic ice cores and conclusively elucidate the role of CO2 and deep-ocean ventilation in glacial-interglacial climate change. Undertaking this challenging research plan will lead to the creation of the first record of atmospheric CO2 concentration beyond the temporal extent of ice-core based CO2 records. This will improve our understanding of climate evolution during MPT, the precursor of modern day climate. This undertaking will focus on testing the evolution climate sensitivity to atmospheric pCO2 and deep-ocean overturning, across the MPT to better quantify the changes in feedback mechanisms that led to an increase in amplitude and drop in frequency of the glacial- interglacial cycles. The outstanding plaeoceanographic questions that will be answered are: the role of CO2 play in the MPT; specifically , across the 900 kyr event, and if there indeed was a decline of atmospheric-pCO2 during MPT, what role did deep-ocean circulation and changes in its carbon reservoir play in it?

164 Marine Geology and Geophysics

Crustal architecture and tectonic evolution of the Western Ghats and status of the major tectonic Shear Zones of Southern Granulite Terrain (SGT), and their oﬀshore extension: An Integrated Geophysical approach QUICK ORAL Zeba Nezrin F. K, Ajayakumar P OSICON2021/218 Department of Marine Geology and Geophysics, School of Marine Sciences, Cochin University of Science and Technology, Kerala

The Western Continental Margin of India (WCMI) is formed during the breakup of India and Madagascar by the product of three temporally distinct rifts around 145Ma, 90Ma and 65Ma by large plume generated activity. The Western Ghats (WG) is a mountain range extending about ∼1500km which traverses parallel to the WCMI, whose evolutionary history is still ambiguous. The integrated geophysical techniques can elucidate the causes responsible for the evolution of the WG and for deciphering the crustal structure. The combined ground, airborne and satellite Gravity and Magnetic studies are undergone to delineate the lithosphere structure, mantle dynamics and tectonic evolution of the WG, and to understand the tectonic status of the major lineaments including the Palghat- Cauvery Shear Zone (PCSZ), Moyar- Bhavani- Bavali Shear Zones and Achankovil Shear Zone (ASZ), and their offshore extensions to the Konkan-Kerala Basin. These three major shear zones dissect the WG in three different parts in its stretch. The studies in the Konkan- Kerala Basin can explain whether any offshore elongation of the above-mentioned shear zones is present, which can clarify the evolution of the WG and associated tectonics. Several researches have shown that the extension and breakup in the passive continental margins cause crustal thinning, which effect in the continental plateau with great escarpments, and also the tectonic unroofing causing the rift-flank upliftment. The Moho depth is calculated using the power spectrum analyses and the crustal structure is estimated by the gravity and magnetic data modelling. Modelling the overall deep and shallow continental structures across the Western Ghats, and mid and low lands towards the west coast, throw light on three phases of Pre-Cambrian and post Mesozoic evolutions of the region. The model may support a tripartite geomorphic division of the region.

165 Marine Geology and Geophysics

Reconstruction of Indian monsoon variability since last glacial maxima from the Bay of Bengal QUICK ORAL Nayana V Haridas1,2, Upasana S. Banerji1, Maya K1, D. Padmalal1 OSICON2021/279 1National Centre for Earth Science Studies, Ministry of Earth Science, Thiruvananthapuram; 2Department of Marine Geology and Geophysics, Cochin University of Science and Technology, Kochi

Bay of Bengal (BoB) is a semi-enclosed basin of the north-eastern Indian Ocean which receives large quantity of fluvial and sediment input primarily from the Hi- malayan and the peninsular rivers. The riverine flux into the BoB is a function of Indian monsoon (both summer and winter) intensities. The Indian Summer Mon- soon (ISM) causes dominant rainfall over the Indian landmass, while the eastern coast and the north-eastern region witness winter precipitation caused by North East monsoon (NEM). Thus, the BoB and its nearby regions provide a unique opportunity to investigate the paleomonsoon variabilities of both ISM and NEM during the glacial-interglacial periods. In view of this, an effort has been made here to investigate the Indian monsoon variability since the Last Glacial Maxima (LGM: ∼last 20 ka), considering the BoB and its nearby regions. The study invoked intensified NEM with simultaneous weakening of ISM during LGM and this is accompanied by a marked decline in Sea Surface Temperature (SST). The NEM strengthening led to enhanced sediment and water discharges from the peninsular rivers while reduced discharges from the Himalayan rivers is observed in the northern and western BoB during LGM. Furthermore, the ISM strengthening was observed during Bølling- Allerød (B/A: ∼14 ka) and Holocene with an intermittent ISM weakening during the Heinrich event (H1: ∼16 ka) and Younger Dryas (YD: ∼12 ka). The ISM intensification during the Holocene has been associated with high solar insolation while the ISM strength gradually declined towards late-Holocene in tandem with the reduced solar insolation. The present study on the paleoclimate and paleoceanographic reconstructions from the BoB could provide a better understanding of the changing monsoon intensities and its teleconnection with the global climate variables.

166 Marine Geology and Geophysics

Role of in-situ and Meteoric 10Be in Quaternary Glaciation, Marine Chronology and Paleomagnetic Reconstruction ORAL OSICON2021/282 Ravi Bhushan, Partha Sarathi Jena, Shivam Ajay PRL-AMS Lab, Geosciences Division, Physical Research Laboratory, Ahmedabad

Beryllium-10 (10Be) is produced in the atmosphere by the interaction of cosmic-ray particles mainly with oxygen and nitrogen and in-situ by interaction with silicon and oxygen in surface rocks. Cosmogenic 10Be has found varied applications in earth science processes. With the advent of the Accelerator Mass Spectrometer (AMS), the meteoric 10Be (half-life of 1.39 Ma) has been used as a tracer for understanding earth surface processes on millennial time scales. The in-situ produced 10Be is most widely used for exposure age dating. In contrast, meteoric 10Be has been utilized for understanding variation of denudation rates, dating marine cores, and reconstruction of paleomagnetic events. Strategically, the meteoric 10Be dating method can date events as old as 10 Myr, and its accuracy while dating marine sediment cores has been well tested with magnetic methods. To constrain the chronology of past-glaciation in Himalayan region, both terrestrial cosmogenic nuclide (TCN), and Optical stimulated Luminescence (OSL) dating has been employed. However, the samples suitable for luminescence dating are very limited and difficult to find. On the other hand, glacially eroded bedrocks and boulder samples can be utilized to build chronology of past glaciation using TCN method. The chronology of quaternary glaciation of the Ladakh Himalaya using in-situ produced 10Be extracted from glacially eroded bedrocks and moraine boulders has been made. Meteoric Beryllium measured from marine sediment cores can also be employed to reconstruct past magnetic field strength records. Authigenic derived beryllium isotopes have been measured from the sediment samples covering the northern Indian ocean to understand processes controlling their distribution. Meteoric beryllium has also been employed to build chronology of sediment cores beyond 50 ka and to understand past geomagnetic field variations. Both in-situ and meteoric 10Be can be potentially used to understand paleoclimatic and paleomagnetic events during the quaternary period. In this presentation, results obtained from PRL-AMS (AURiS- Accelerator Unit for Radio-isotope Studies) laboratory will be presented and various applications of meteoric and in-situ beryllium will be discussed.

167 Marine Geology and Geophysics

Role of Weathering and Reverse weathering in Global Carbon cycle ORAL OSICON2021/302 Juzer Shaikh Indian Institute of Science, Bangalore

Earth’s climate has been supported by stabilizing feedbacks to remain persistent.

CO2 regulation via negative feedbacks within the global carbon- silica cycles are classically viewed as processes that govern the climate stability on Earth. Marine processes are an essential component of the canonical silicate weathering feedback and have played a much more critical role in pCO2 regulation. Carbon enters the ocean-atmosphere reservoir through solid Earth degassing of CO2 and is lost through the sequestration of carbon as carbonate precipitation.

XSiO3 +CO 2 ←→ XCO3 + SiO2. 2+ 2+ (XCO3, here and elsewhere X represents a divalent cation, typically Ca , Mg 2+ or Fe ) or biomass (CH2O) This so-called Urey equation represents the inorganic carbon cycle. Weathering of a silicate mineral (XSiO3) is coupled to the removal of carbon as carbonate and silicon as chert (SiO2). Weathering of continental rocks consumes CO2 and modulates cation fluxes to the ocean, thereby playing a critical role in controlling long-term seawater chemistry and climate. However, this sink was potentially dampened during Earth’s early history when oceans had higher levels of dissolved silicon (Si), iron (Fe) and magnesium (Mg). It instead likely fostered more extensive reverse weathering, which in turn fostered higher ocean- atmosphere CO2. The formation of authigenic silicate minerals consumes alkalinity and generates acidity; a process classically referred to as reverse weathering. Reverse weathering is a key parameter of Earth’s superficial coupled silicon- carbon cycle that can play a major part in controlling the atmospheric composition and seawater chemistry. Below is a classic equation for reverse weathering; 2+ 3− 3X + 2H4SiO4 + 6HCO ←→ X3Si3O5(OH)4 + 6CO2 + 5H2O Reverse weathering in coastal and abyssal regions of the ocean plays a critical role in modulating the long-term (101 to 106 year timescale), mass budget and isotope composition of dissolved constituents of seawater and the concentration of atmospheric CO2. Although the kinetics of reverse weathering are far sluggish today, there are shreds of evidence that suggest more prolific reverse weathering rates persisted in past climate. Both these processes point towards an intricate balance of the Earth system in controlling CO2 levels and in extension temperature, which makes them topics of concern.

168 Marine Geology and Geophysics

Paleoclimate variability and global teleconnection during Northgrippian-Meghalayan stages from the Southern India ORAL OSICON2021/303 Upasana S. Banerji1, Jithu Shaji1, Maya K1, A.K. Sudheer2, Ravi Bhushan2, D. Padmalal1 1National Centre for Earth Science Studies, Ministry of Earth Science, Thiruvananthapuram; 2Physical Research Laboratory, Ahmedabad, Gujarat

The global atmospheric circulation has been the major driving factor for the variability of the Indian Summer Monsoon (ISM) and thereby impacting the climate and socioeconomic conditions of the Indian subcontinent. Southwestern India acts as a gateway for the ISM advancement over the Indian landmass and provides an ideal platform for investigating the transition phase for the recently proposed North- grippian and Meghalayan stages. A sediment core of nearly 4 m length raised from a freshwater lake was chronologically supported by six AMS radiocarbon dates and was investigated to unravel the paleoclimate variability and global teleconnections. The geochemical and isotopic proxies demonstrated dry climate caused by weak ISM during 3.5-3.7 ka and 4.7-4.9 ka interrupted by a strengthened monsoon spell. Both the period of dry climates has been attributed to reduced Total Solar Irradiance (TSI). Further, the reduced TSI especially during 4.7-4.9 ka was accompanied by increased El Ni˜noevents. These observations are in agreement with the declining temperature reported from SE Arabian Sea and Greenland Ice Core records. A vital role of TSI in controlling the ISM variability is envisaged with the possible occurrence of El Ni˜noevent restricting ISM during 4.7-4.9 ka, and thereby triggering the 4.2 ka dry climate over the Indian subcontinent. The study has implication on understanding the behaviour of ISM along with the possible role of global forcing during the transition phase of Meghalayan-Northgrippian Stages.

169 Marine Geology and Geophysics

Paleoclimate and Sea-Level Variability during Holocene epoch from Coastal Lowland Sediments of Kerala, SW India QUICK ORAL Jithu Shaji1,3, Upasana S. Banerji1, Maya K1, Kumar Batuk Joshi1, Ravi OSICON2021/315 Bhushan2, D. Padmalal1 1National Centre for Earth Science Studies, Ministry of Earth Science, Thiruvananthapuram; 2Physical Research Laboratory, Department of Space, Ahmedabad, Gujarat; 3Department of Marine Geology and Geophysics, Cochin University of Science and Technology, Kochi

Holocene epoch has witnessed several phases of climatic perturbations accompanied with marginal sea level variations. However, the instrumental records are limited that seldom goes beyond last two centuries. The Holocene epoch over Indian subcontinent has been recognised as a function of Indian Summer Monsoon (ISM) variability as it leads to >70% of the rainfall over Indian landmass. The southwestern coast of India acts as a gateway for the ISM and thus provides an ideal platform to investigate ISM as well as the simultaneous sea level variability during the Holocene epoch. In the present study, a sediment core with a length of nearly 32 m was retrieved from Kuttoor region, SW Kerala, India, in order to investigate the coupled effects of sea level and climate variability. A multiproxy approach was made on the sediment core and was chronologically constrained with nearly 10 AMS radiocarbon dates. The study suggested a marine transgression accompanied with ISM strengthening during 96907560˜ cal yr BP followed by gradual marine regression. This corroborates well with the Holocene Climate optimum that persisted during 90005000˜ yr BP. A hiatus in the form of peat section is observed between ∼7560 and 3510 cal yr BP following which a weak monsoon till 2550 cal yr BP is observed but with an intermittent monsoon spell during 34003200˜ cal yr BP. last 2550 cal yr BP, the region witnessed riverine sediments deposition facilitated by the adjacent Manimala and Pamba rivers which further underscored the absence of marine influence caused by the sea regression. The heavy rainfall and high sea level during the early Holocene epoch must have resulted in a possible southward extension of Vembanad Lagoon located in the north of core location. The present- day configuration of Vembanad Lagoon could be a combined result of marine regression along with heavy riverine sediment input which followed.

170 Ocean Engineering and Technology (OET)

Sessions’ Chairman

Dr. M. A. Atmanand Indian Institute of Technology (IIT) - Madras, Chennai, Tamil Nadu

Dr. N. P. Kurian Ocean Society of India

Prof. Prasad K Bhaskaran Indian Institute of Technology (IIT) - Kharagpur, West Bengal

Dr. R. Venkatesan National Institute of Ocean Technology (NIOT), Chennai, Tamil Nadu

171 Ocean Engineering and Technology (OET)

Invited Talks

INVITED TALK 1: Recent trends in Coastal Research and Sustainable Coastal Technologies

Dr. M. V. Ramana Murthy

National Centre for Coastal Research (NCCR), Chennai, Tamil Nadu

INVITED TALK 2: Coastal processes and coastal protection challenges

Dr. Joseph Mathew

Sanctuary Beach Pvt. Ltd., Singapore

INVITED TALK 3: Technology for exploration of Ocean Resources

Dr. G. A. Ramadass

National Institute of Ocean Technology (NIOT), Chennai, Tamil Nadu Ocean Engineering and Technology

Optimization of Floating Oﬀshore Platforms for Wind Energy in Indian Coast QUICK ORAL Arya Thomas OSICON2021/13 Cochin University of Science and Technology, Kalamassery

The sub-structures for supporting a floating offshore wind turbine are modeled and analyzed for the southern coast-off Kanyakumari. A SPAR and Semi- submersible platforms are adopted for the same to support a 5MW turbine, which are used for two different locations in the specified coast. This work aims to study the dynamic response of the baseline and large floating offshore wind turbine (FOWT). An upscaling method is adopted based on the turbine power ratios to increase the baseline platform dimensions and geometry to support 10MW DTU turbine. A suitable scale factor is chosen after an iterative process. Thus, more power can be extracted from the upscaled platform that is deployed in the same site as its baseline equivalent. A coupled aero-hydrodynamic analysis of the entire system including wind turbine, platform and mooring lines is performed to determine the integrated response and power generation capability of the turbine. A turbulent wind condition with irregular waves, both headed in 0 0 is used for the simulation in OpenFAST. The time domain results obtained are converted to spectra (frequency domain) using MAT- LAB scripts. The results are compared between the baseline and its corresponding upscaled platform. It is observed that the dynamic response is maximum at the turbine’s rated wind speed. The current upscaling method can be used as a preliminary method to design large floaters. The variation of the displacements and power output is also presented. The response in the survival/parked condition is found to be less than the operating condition. The coupled dynamic analysis makes it clear that, among the motions, aerodynamic loads and gyroscopic effect of the rotor in the operational load case largely affect surge of all platforms. Mostly, the waves and also the controller of the turbine affect the pitch motion. Increase in wind speed causes significant heave motions. The upscaled SPAR platform and baselineSSP proved to be used as a platform for the selected coast.

173 Ocean Engineering and Technology

Experimental study on the Maneuvering of a Container Ship in Regular waves ORAL OSICON2021/47 Rameesha T V1, P. Krishnankutty2 1 KMEA Engineering College; 2 Indian Institute of Technology, Chennai

Traditionally, assessment of ship maneuvering characteristics is carried out in calm water conditions, thus ignoring the effect of the wave on the ship hydrodynamic behaviour. Effect of sea waves alter the water particle kinematics around the ship and subsequently the hydrodynamic forces acting on it, resulting in the change of ship steering and control characteristics. In the present study, free running model tests on turning maneuver are conducted on a container ship in calm water and also in regular waves at the Seakeeping and Maneuvering Basin (SMB) facility of Naval Science and Technological Laboratory (NSTL), Visakhapatnam. The turning tests on the self- propelled model are conducted in calm water and in regular head sea waves with different heights and length to understand the effects of wave parameters on the turning characteristics of the vessel. Turning and course changing qualities of a vessel can be estimated by conducting turning circle test. Turning circle tests are conducted in still water and in regular head sea waves. Tests are carried out for different model wave heights such as 0.013m, 0.019m and 0.026 m and also for dif- λ ferent wave lengths such as 1.5m, 3m, 4.5m, 6.0m and 7.5m ( L = 0.5, 1, 1.5, 2, 2.5). Estimated steady turning radius is increased by 10.1% and other parameters like transfer and tactical diameters also increased by 2.31% and 1.35% respectively and advance is reduced by 21.8% in head waves compared to still water condition. The waves generally affect the turning trajectory significantly and cannot be neglected. Turning circle trajectory in still water condition for the present study are matching well with the earlier reported results. Compared to the trajectory in calm water, vessel trajectory in waves are found to drift towards the direction of wave propagation and the vessel drift increases with height of first order wave. Wave length also has a considerable effect on maneuvering. Longer waves has less effect on turning characteristics of the ship. The present study shows that wave significantly affects the maneuvering characteristics of the ship and hence it is recommended to assess the controllability of a seagoing vessel in the presence of waves rather than in calm water condition, as conventionally done.

174 Ocean Engineering and Technology

Variability and distributional analysis of extreme swell wave energy ﬂux in the Indian Ocean ORAL OSICON2021/54 S Sreelakshmi, Prasad K Bhaskaran Department of Ocean Engineering and Naval Architecture, Indian Institute of Technology Kharagpur, Kharagpur

Ocean waves are comprised of two or more wave systems travelling along the great circles. Transport of certain amount of energy along with this is well documented, whereas, the individual contribution of wave systems is hardly studied. This analysis presents a detailed climatological assessment of swell wave energy flux in the Indian Ocean (IO) using a forty- two years of wave data generated by European Centre for Medium-Range Weather Forecasts. A better representation of extreme swell wave energy is described using generalized extreme value (GEV) analysis for different seasons in the IO and the maximum value is estimated as 410 KW/m during JJA (June–July–August). The directional wave energy flux is quantified incorporating the two directional parameters of Directional spread and mean wave direction. These parameters along with significant wave height and wave energy period are attributed to the energy and directional distribution of IO waves in different basins. A detailed assessment on the annual and seasonal variability of wave power density and direction is also included. The coefficient of variability, seasonal, and monthly variability indices are estimated for extreme wave energy climate. The similar analysis was conducted for the directional energy flux for both deep and shallow regions.

175 Ocean Engineering and Technology

Physical model studies on damage and stability analysis of breakwaters with double layer GSC armour units ORAL OSICON2021/65 Reshma George V National Institute of Technology, Karnataka

Breakwaters are structures that are built to dissipate the dynamic energy of wave action and thus provide a tranquility condition at its lee side. Rubble mound breakwaters are one major type of breakwaters used for shore protection, which is very expensive. The present study focuses on the viability of using Geosynthetic sand containers as armour units for a breakwater structure in place of the stone and concrete armours of conventional breakwaters. Two layers of geotextile sand containers of 100% fill ratio are arranged in three different patterns namely parallel, Flemish and slope and experimentally tested for their hydraulic stability. The water depths considered are 40, 45 and 50 cms. Wave heights ranging from 6 cm to 14 cm with time periods ranging from 1.4 s to 2.2 s, confining Mangalore coast conditions are used for physical modelling. A 1:30 scaled experimental investigation for damage and stability analysis of the proposed GSC breakwater was carried out in a two- dimensional monochromatic wave flume. Geosynthetic sand containers (GSC) are an excellent cost effective, soft and environment friendly alternative to heavy armour stones. This study discusses the variation of stability number (Ns)with surf similarity parameter (ξ0 ) and also the effect of incident wave heights on damage levels. It was found from the studies that stability number decreases with surf similarity parameter and the damage levels keep on rising with incident wave heights. Double layered parallel arrangement was found to be the most stable one among all patterns of arrangement.

176 Ocean Engineering and Technology

Real-Time Estuary Observatory System for Monitoring Bhavanapadu Estuary by Utilizing Internet of Underwater Things ORAL OSICON2021/66 Teppala Vikranth1,2, S.S.V.S. RamaKrishna1, R. Srinivasan2 1Department of Meteorology and Oceanography, Andhra University College of Science and Technology 2Ocean Electronics, National Institute of Ocean Technology

An estuary is a location where saltwater from the coast mixes with inland freshwater. This is the place of interaction between the two different water masses which alters the water properties in the estuary. The change of water properties is highly dynamic in nature which is influenced by the frequent tidal currents as well as freshwater input from the estuary head. A Real-Time Estuary Observatory System (REOS) has designed to investigate the variability of properties in the estuary such as the mixing behaviour of water temperature and salinity, tidal current (Flood & Ebb) velocity and direction on the surface and bottom, and the spatial & temporal properties (surface water temperature and salinity). REOS consists of five different platforms such as Moored Buoy Observatory, Tilt Current Meter, Shal- low water Surface Drifter, Remotely Operated Surface Vehicle, On-board measuring unit, and Recurrent Neural Network. All these platforms work autonomously and semi-autonomously. These platforms collect the required data in the estuary with the help of two sub-systems such as Surface Data Acquisition System (SDAS) collects data in the air & the water surface and Sub- Surface Data Acquisition System (SSDAS) collects data below the water surface in the estuary. This observatory system collects the real-time in-situ data and sends it to the base station by utilizing the Internet of Underwater Things which is an Internet of Things platform. The downloaded data is purified, analysed, and given to the artificial neural network to forecast the future behaviour of the estuary. REOS deployed on 20/03/2020 at 1 pm IST at Bhavanapadu estuary (Lat 18.5616, Lon 84.3494) located on the North East coast of Andhra Pradesh adjoining the Bay of Bengal sea. Eight days of real- time in-situ data have collected by the observatory which shows that all the physical properties (water temperature, salinity, underwater pressure, and flow of current) are highly influenced by the tidal current in the estuary. During the tidal current, the estuary is slightly stratified and the estuary mouth is vertically mixed.

177 Ocean Engineering and Technology

Variability and accuracy in the estimation of sound speed in Indian waters ORAL OSICON2021/86 Akhil Varghese1, Anand P.2, Raju R. P.2 1Kerala Univ. of Fisheries & Ocean Sciences (KUFOS), Panangad, Kochi 2Naval Physical and Oceanographic laboratory, Kochi

The speed of sound in water depends on the physical properties of sea water (D, T, S) and varies with time, and location. The vertical distribution of sound speed determines the path of the sound propagation and hence the determination of sound speed profile (SSP) is very much important for acoustic propagation. Most of the oceanographic studies, estimate SSP as a derived quantity (from T, S), instead of direct measurement. For SSP, different equations have been proposed by researchers developed based on laboratory measurements and experiments. Interestingly, none of these equations are tested for Indian waters and established their accuracy. Here, a study is carried out to see the variabilities of estimation of SSP in the Indian waters. It is done based on the climatology data for the Arabian sea (AS) and Bay of Bengal (BoB) representing coastal as well as open ocean (deep) stations for four seasons. Stations at northern part of AS and BoB were also considered to see the effect of salinity in these equations. The table shows that maximum variability is noticed in the coastal waters and that too in the thermocline region (100-500m). In the case of northern region, at the surface (0-100m), the SSP variability is large in AS whereas in the thermocline region, it is higher in BoB. In addition to the climatology, direct measurement of sound speed using sound velocity profiler (M/s AML Oceanographic) is also utilized from a single point to compare these profiles with ground truth. The comparison shows that, even though there is large difference in the sound velocities computed with various equations. This needs to be further evaluated with a larger dataset of directly measured sound.

178 Ocean Engineering and Technology

Air Quality Monitoring from Deep Ocean Moored buoy systems in the Indian Ocean ORAL OSICON2021/88 B.Kesavakumar, G.Vengatesan, M. Arul Muthiah, R. Venkatesan National Institute of Ocean Technology, Ministry of Earth Sciences. Govt. of India, Chennai

Atmospheric air pollutants such as particulate matter (PM 2.5,10,1), Carbon monoxide, NOx, SOx, Methane, Ozone, etc. are measured to calculate the air quality index (AQI). Presently these monitoring systems are installed on the mainland for measurement and prediction of various air quality parameters on land. As for as the oceanic area is concerned, the in-situ observation of air quality parameters is very scarce. Sustainable development goal 14 deals with the life below water and man- dates to prevent and reduce marine pollution of all kinds. The Global Atmosphere Watch (GAW) programme of WMO also emphasizes the importance of in-situ measurements of air quality parameters in the ocean. OMNI (Ocean moored buoy Network in the Northern Indian Ocean) buoy systems are located at strategically selected 12 deep ocean locations and 3 coastal buoy systems are deployed at the Bay of Bengal and Arabian sea. These buoy systems are equipped with state of the art sensors for measurement of Meteorological, sea surface and sub-surface water parameters up to a depth of 500m. The data from these buoy systems are used for providing critical cyclone warnings to coastal communities, long-term oceanographic research, air-sea interaction studies, satellite calibration and validation, etc. The reliability of these buoy systems is improved from the ﬁeld experience gained from the last two decades. This paper explores the opportunity of using the existing buoy network for additional augmentation of air quality sensors for eﬀective monitoring and real-time dissemination of air quality parameters along with other buoy parameters. The available sensor technology for the measurement of air quality parameters, their suitability for mounting in hostile marine environment conditions, additional power requirements will be presented in detail. The air quality data along with the meteorological data from the buoy system can provide more insights on the presence of air pollutants and the extent of increased pollutants reaching from the mainland to coast and ocean from various sources including ships. This work will improve the understanding of the performance of presently available air quality sensors when subjected to marine environment condition and facilitates new development.

179 Ocean Engineering and Technology

Experimental studies on coastal dyke made of geotextile sand Containers with coarse aggregate as bedding, core & secondary Layers ORAL OSICON2021/93 P. Vijay Charles, T. Nasar Department of Water Resources and Ocean Engineering, National Institute of Technology, Karnataka, Surathkal

Coastal dykes made of Geotextile Sand Containers (GSCs) are increasingly incorporated into coastal management solutions because of their cost-effective and environ- mentally friendly characteristics. A range of successful coastal protection structures using GSCs has been constructed in many parts of the world, especially in Germany. The hydraulic processes affecting the stability of GSC structures were extensively investigated. Nevertheless, GSC is still an emerging technology, and no proper guidelines are yet available for the design of GSC structures on a sound scientific base. These coastal dykes reduce the wave action on the lee side by forcing wave breaking, and their stability is a function of the relative crest width, crest height, and the damage. A 1:30 scaled physical experimentation is chosen as a preliminary investigation to test the feasibility of using GSCs with single layer as a Coastal dyke. The present work involves a physical model study on 1V:2H sloped trapezoidal dyke constructed with 385 gm GSCs as the primary layer. Coarse aggregate of 0.025m as Secondary layer and 0.02m as core, also 0.05-0.06m as the bottom layer. Also, two toe berms are placed on both seaward and leeward sides, which comprised of 0.025m coarse aggregate with different alignments like Parallel to wave, Parallel to the slope of structure, and Flemish. Structure height (h) of 0.6 m and two bags of crest widths (B) and are tested for stability and reflection for wave heights (H) of 0.6m, 0.8m, 0.1m, 0.12m, 0.14m, and wave periods (T) of 1.4s, 1.6s, 1.8s, 2.0s,2.2s in a water depth (d) of 0.4 m, 0.45m, 0.5m. The stability of structure is studied by sending 2000 to 3000 waves approximately. Also reflection is done for three trails. Experiments revealed that the best performing configuration could withstand wave heights up to 2.7 m.

180 Ocean Engineering and Technology

Ocean observation buoy powered using wave energy ORAL OSICON2021/94 Ashwani Vishwanath, Biren Pattanaik, Purnima Jalihal, K. S. Sajeev, Y. V. N. Rao, A. Karthikeyan National Institute of Ocean Technology (NIOT), Chennai

The article describes the features of the indigenously developed wave powered buoy and field demonstration the system for usage in ports and harbors. As a part of the research on floating wave powered devices, NIOT team has successfully developed and demonstrated an all weather floating Wave Powered Navigational Buoy system in the sea for powering a beacon lamp on top of the buoy and oceanographic related components using energy extracted from the ocean waves. This floating buoy is sized for the navigational requirements and can be used as a navigational buoy in ports and harbours or acts as an ocean observation buoy independently. Wave powered buoy is of similar size as that of solar powered navigational buoy. The charging of battery is done utilizing the wave power using the principle of Oscillating water Column (OWC). The buoy is designed to generate electricity in even in low wave climate prevalent in Indian waters. The buoy has undergone several sea trials off Kamarajar port in Chennai and is currently in operation near the port’s navigational channel. This wave energy device consists of floating body, oscillating water column, power module comprising of turbine and generator assembly and battery charging electrical system. All the components were designed in-house and fabricated locally. During the demonstration in open sea, in- situ measured oceanographic parameters like wind, current, pressure, water temperature were hourly transmitted to port or local authorities through GSM communication by in-house developed data- logger system. Besides serving the purpose as a navigational aid, the buoy can also be useful for real time assessment of these oceanographic parameters. The energy produced is sufficient to power almost all the oceanographic sensors present in a conventional ocean observation buoy except wave measurement, since the system uses wave energy for the power generation. The technology of this indigenously developed product has now been transferred to few reputed industries for propagation of this low cost device. The article also details the oceanographic measurements recorded by the system for several months during its demonstration period in open sea off Chennai.

181 Ocean Engineering and Technology

Comparison of Vector Sensor Array Processing algorithms for Underwater Source Localization ORAL OSICON2021/95 Shweta Lokhande1, G. Latha1, S. Srinivasan2, A. Malarkodi1 1National Institute of Ocean Technology, Chennai; 2Madras Institute of Technology, Chennai

Underwater source localization in shallow waters is very challenging due to the wave guide nature of the environment, reflections from surface and seabed. A vector sensor array provides higher directivity with smaller aperture than an array of traditional hydrophones and enables accurate estimation of range and Direction of Arrival (DoA) of source. There are many algorithms developed for estimation of DoA for underwater sound sources. Some of the methods are Classical Delay and Sum Beamformer, Minimum Variance Distortion less Response, Conventional Beam- former, ESPRIT and Multiple Signal Classification (MUSIC) Algorithm. MUSIC algorithm has advantages over other estimation algorithms because it is efficiently estimating the independent source signals with high precisions. A unified approach is presented for recovering signal parameters from noisy observations, using singular value decomposition (SVD) in existing MUSIC algorithm. The SVD of a matrix constructed from the observed signal data provides the key step in a robust discrim- ination between desired signals and disturbing signals in terms of signal and noise subspaces. This work presents the comparison of DoA estimation from conventional beamformer, MUSIC and modified MUSIC algorithm. Comparison is carried out using lab experiment conducted at Acoustic Test Facility of National Institute of Ocean Technology, Chennai for different position and different Azimuth angles for discrete frequencies from 1kHz to 6kHz with different azimuth angles. The results demonstrate that the modified MUSIC algorithm has better direction-finding performance as compared to other methods.

182 Ocean Engineering and Technology

Eﬀect of Mooring Motion on Temperature Proﬁle Measurements in OMNI Buoy Systems: A Case Study ORAL OSICON2021/105 Biswajit Haldar, Abhishek Tandon, K. Jossia Joseph, M. Arul Muthiah, P. Senthilkumar, R. Venkatesan Ocean Observation Systems, National Institute of Ocean Technology, Chennai, India

The temperature variability in the mixed layer and upper thermocline plays a significant role in upper ocean dynamics and affects the weather systems. Ocean temperature profile measurements are important in understanding the dynamic nature of global climate and marine ecosystem. The ocean heat content from the surface to the depth of 26oC isotherm (D26) known as tropical cyclone heat potential (TCHP) has a major influence on tropical cyclone (TC) intensification. The accurate measurement of ocean temperature profile is very much important for the scientific community and researchers who are working in the field of oceanography. National Institute of Ocean Technology (NIOT) manages a network of 12 OMNI (Ocean Moored Buoy Network for northern Indian Ocean) buoys systems that measure meteorological and oceanographic variables along with temperature and salinity profile measurements in north Indian Ocean. Subsurface temperature measurements from OMNI buoy systems are subject to change due to upward movement of the mooring line which depends on both the environmental condition and mooring design. All the OMNI buoy systems are deployed with slack-line moorings, which responds more to wind, wave, and current forcing compared to taut- line mooring. The standard sensor fit of the OMNI buoy systems has the sea surface temperature sensor at 1 m depth and sub-surface temperature sensors at different depths up to 500 m (5, 10, 15, 20, 30, 50, 75, 100, 200, and 500 m) in a jacketed wire rope and only one pressure sensor fixed at 500 m. To assess the upward movement of the mooring line, a case study with four additional pressure sensors (10 m, 50 m, 100 m and 200 m) apart from the standard depth at 500 m is carried out for one-year period in central Bay of Bengal. The analysis shows that the maximum value of average temperature deviation is 0.53oC in the lowest instrumented depth where the line experiences a greater range of motion and the actual temperature variability in shallower depths is negligible particularly up to 75 m (<0.01oC).

183 Ocean Engineering and Technology

Soundscape in Summer in Kongsfjorden, Arctic ORAL OSICON2021/108 Sunil Kumar Mohanta, G. Latha, M.C. Sanjana, E. Arunbabu National Institute of Ocean Technology (NIOT), Ministry of Earth Sciences, Chennai

Ambient noise measurements in glacialfjords is dominated by glacier melt, freshwater discharge and ice dynamics.The Arctic sea ice cover is decreasing year by year due to global warming and in order to understand the different ice melting processes passive acoustic observation is very important.The present work focuses on the analysis of underwater noise generated by melting of icebergs in a glacierized fjord. The number and size of air filled pores in the glacier ice and the high pressures inside them result from the bulk compression of snow during its transformation to ice.Quick variation of temperature between ocean surface and the atmosphere produces a temperature gradient, due to which iceberg starts melting. The highly pressurized air bubble which was previously trapped inside the iceberg generates underwater noise during melting. The Automated Ambient Noise Measurement System (ANMS) deployed as part of IndARC mooring by the National Institute of Ocean Technology (NIOT) along with NCPORat an ocean depth of 198 m in July 2015 has been operational since then and the noise data sets in summer 2017 are used in this study. IndArc system consists of sensors for sub surface measurements such as CTD (Conductivity Temperature & Depth), Current meter,PAR(Photosynthetically Active Radiation) sensor along with hydrophone. Hydrophone deployed at a depth of 45 m from the sea surface acquired data hourly with a sampling frequency of 25kHz for a duration of 180 seconds. In the year 2017, July, August and September datasets have been used here for spectral Analysis and source identification. Sound Pressure Level estimation is carried out using modified Welch’s Power Spectral Density Method. After analyzing the three months data a variety of noise signaturesdue to Geophonic and Anthropogenic sources, have been detected. Iceberg calving, and bubbling noises under geophony, shipping noise and helicopter noise under anthrophony have been found to be the major components of sound scape in the summer in the Arctic fjord. Spectrogram,Spectral density estimates and audio files have been used for the identification and analysis of underwater noise.Instrument in the mooring was detected and filtered. Iceberg calving noise falls in the frequency band below 500Hz. Bubbling noise was observed in the frequency below 1500 Hz.Shipping noise was observed in the frequency below 600Hz

184 Ocean Engineering and Technology

Internal tide energetics in the Andaman Sea QUICK ORAL B. Yadidya1, A. D. Rao1, G. Latha2 OSICON2021/128 1Centre for Atmospheric Sciences, Indian Institute of Technology Delhi, New Delhi; 2National Institute of Ocean Technology, Pallikaranai, Chennai

A 3D MITgcm is used to understand the variability of internal tides in the Andaman Sea. Realistic experiments are conducted for different seasons to simulate internal tides by considering the background circulation and stratification from Ocean Re- analysis System 5. They are validated with in-situ observations at BD12 and RAMA buoy along with tidal gauge data at Port Blair, Moulmein, Ko Taphao Noi, and Sabang. Furthermore, idealized experiments with horizontally homogeneous stratification are also carried out to examine the influence of background field on the generation and propagation of internal tides. The comparison between realistic experiments and idealized experiments helped in quantifying the relative importance of astronomical tidal forcing and background stratification to the energetics of internal tides in the Andaman Sea.

185 Ocean Engineering and Technology

Wave spectral characteristics of Two concurrent Cyclones Kyarr and Maha in the Arabian Sea ORAL OSICON2021/138 R. Keerthivasan1,2, G. Latha1, R. Balamurugan2 , R. Venkatesan1 1National Institute of Ocean Technology, Ministry of Earth Sciences, Chennai 2College of Engineering, Anna University, Chennai

The Indian Ocean monsoon is an example of powerful ocean-atmosphere interaction at basin scales, and the Arabian Sea plays a significant role in modulating the Indian Ocean monsoon. Climate change has increased the frequency of cyclones in the Arabian Sea. Ocean waves play an important role in sea-keeping safety, offshore structure design, ship passages and surf forecasts and especially during cyclone passages they provide vital information. This paper presents the wave spectral characteristics in deep waters during two concurrent cyclones i.e., Super Cyclonic Storm (SCS) - KYARR and Extremely Severe Cyclonic Storm (ESCS) MAHA in the Ara- bian Sea during October-November 2019. The data from the OMNI buoy (Ocean Moored Buoy Network for the Northern Indian Ocean) AD06 (18.5oN/67.5oE) in the Arabian Sea, has been used. The National Institute of Ocean Technology maintains a network of moored buoys that measure surface meteorological and oceanographic data such as wind, currents, wave, temperature, and salinity. During the Cyclone Kyarr, the maximum measured significant wave height (Hm0) was 7.38m and the maximum wave height (Hmax) was 11.13m. During the Cyclone Maha, the maximum measured significant wave height (Hm0) was 3.29m and the maximum wave height (Hmax) was 5.54m. The minimum distance between the cyclone eye and the buoy is for Cyclone Kyarr and Cyclone Maha are 72km and 73km respectively. With high spectral density at wind wave frequency, the recorded wave spectra were multipeaked before the cyclones and single peaked during cyclones.

186 Ocean Engineering and Technology

Erosion and accretion pattern and shoreline change near Gopalpur port, East coast of India ORAL OSICON2021/147 P.K. Kar1, P.K. Mohanty1, B. Behera1, S. Pradhan2, S. Barik1 1Department of Marine Sciences, Berhampur University 2Chilika Development Authority, Odisha

Gopalpur port (GPL) was a fair weather port and has been developed as an all weather port. Coastal structures associated with the port have been developed in a phased manner. Structures which were developed by June, 2012 include series of groin field in the north of the port with different dimensions, southern and intermediate breakwater of 1249 m and 305 m respectively in the south of the port. After June, 2012, structures developed are three berths of 800 m length and extension of southern/intermediate breakwaters up to 2114/385 m. Therefore, the present study has been carried out to access the shoreline change and erosion/accretion pattern on the south and north of the port, over a stretch of 4.5 Km on both sides. Beach profile and sediment grain size were monitored every month from June, 2012 to May, 2020 at an interval of 500 m while the shoreline was monitored over 9 Km stretch. The results reveal distinct variability in shoreline and erosion/accretion pattern on the north and south of the port. Sediment grain size is predominantly medium, moderately well sorted, symmetrical and mesokurtic in nature. Besides, the study also examined the impacts of VSCS Phailin and Hudhud on coastal structures as well as on shoreline. The results obtained are shared with GPL for its proper management and future course of action. Further, the information generated from the study shall be helpful for the ongoing integrated coastal zone management project funded by the World Bank.

187 Ocean Engineering and Technology

Sustainable production of marine pre-biotic (Polysaccharides and oligosaccharides) using microbial enzymes- future prospects QUICK ORAL Victor Ndilipunye Haimbala OSICON2021/188 Department of Microbiology, Goa University

Prebiotics are carbohydrate compounds composed of vital functional food constituents with distinct role in human health promotions, particularly in maintaining a stable healthy intestinal micro-biota. These components (prebiotics) are non- digestible oligosaccharides that pass through the digestive tract to impact their action in the colon and can be synthesized from various sources such as milk, honey, vegetables and marine algae. According to scholars, marine algae are the most abundant source of bioactive compounds, namely sulfated polysaccharides, phlorotannins and diterpenes and they have been experimentally proven to comprise antiviral and anti-cancer properties, in addition to removal of heavy metals from oceanic water. In this study, we overlook how various algae types are capable of utilization as functional food ingredients, additionally, to enhanced production of polysaccharides and oligosaccharides using microbial enzymes to benefit health and various relevan- cies. Although scientific literature has elucidated the bioactivity of algal prebiotics, molecular structures and biosynthetic pathways accountable for observed physiological functions are deficiently understood. This unbiased review sheds new evidence illustrating that ingested marine polysaccharides’ inability to be hydrolyzed by gut microbiota’s enzymes is due to absence of that enzyme capable to perform the said hydrolysis. Furthermore, this review showed that oceanic biomass is exceptionally huge with numerous bioactive polysaccharides from oceanic algae and invertebrates remains poorly studied due to their complex structures that are not extensively elucidated. Hence, this study suggests protocols and where attention is owed to answer vital significant pending answers as to how these polysaccharides and/or oligosaccharides are metabolized and incorporated into pathways of microbes such as Bifidobacterium spp and Lactobacillus spp and also to better our knowledge in terms of beneficial impact of marine prebiotics.

188 Ocean Engineering and Technology

Wave spectral characteristics in shallow waters oﬀ Goa coast during pre and post monsoon seasons ORAL OSICON2021/187 Reddy Janakiram1,2, G. Latha1, R. Balamurugan2, R. Venkatesan1 1National Institute of Ocean Technology, Chennai; 2Centre for Water Resources, Anna University, Chennai

Ocean waves plays a major role in the design of coastal structures. Wave spectrum, describing the distribution of wave energy across various frequency is important to understand existence of wind sea and swells. Wave spectral characteristics varies during each monsoon season so it is important to study interannual variability. The wave measurements made during the period 2015-2020 by coastal moored buoy CB04 in shallow waters at a depth of 14m at the location off Goa Lat 15.4N: Lon73.7 E have been analysed during Pre-Monsoon (FMAM) and Post- Monsoon (ONDJ). Interannual variability is observed in Jan-Feb and Oct- Nov due to change in wind sea direction. Wave spectrum during non-monsoon shows double peaked spectrum dominated by both swells and wind sea. Multi-peaked wave spectrum is observed in month of Jan due to sea breeze by wind sea and swells from southern Indian ocean. The swell peak energy frequency is varying from 0.07(T p = 14.28s) to 0.08 Hz (T p = 12.5s) indicating that long period waves are observed during non-monsoon season and wind sea peak energy frequency is varying from 0.16 to 0.20Hz. During Feb and March high local winds are observed and the spectrum is wind sea dominated. The average monthly wind speed is low in November, indicating swell dominance. During the pre-monsoon, the average significant wave height is 0.67m with a mean wave period of 5.24sec; during the post-monsoon, the average significant wave height is 0.54m with a mean wave period of 6.11sec. The observations and results are compared with the previous studies on shallow water wave spectral characteristics along eastern Arabian Sea.

189 Ocean Engineering and Technology

Understanding the Pressure Measurement in multi-phase of Open Cycle OTEC power Plant ORAL OSICON2021/205 Y. V. N. Rao, Biren Pattanaik, Purnima Jalihal National Institute of Ocean Technology, Chennai

Ocean thermal energy conversion (OTEC) is a clean source for electricity generation that utilizes the thermal gradient available in World Oceans. National Institute of Ocean Technology (NIOT) has set up India’s first of its kind laboratory to carry out research and development activities on open and closed cycle OTEC. In an Open Cycle Ocean thermal energy conversion (OC-OTEC) process, the system is maintained at lower pressures such that the pressure inside the flash chamber always remains below the vapour pressure of supplied warm water (at 27 to 32oC) by using a vacuum pump. This results into the flash evaporation of a part of the supplied warm water. The generated vapour drives a turbine and generates electricity, before being condensed back to water using cold water drawn from the ocean depths using a surface condenser. This cycle derives the name ”open cycle” from the fact that the condensed water is not returned to the evaporator. This condensed water has very low dissolved solids making it usable for domestic consumption and drinking purpose. In order to generate the maximum power at respective design conditions and also to validate, parameters such as pressure, temperature, flow, need to be studied in detail. Among these, pressures at different stages of the process plays a vital role and is relatively difficult to measure accurately under two phase system. Reduction of pressure loss in the process helps in the optimization of the system design. Thus the measurements of the pressure drop were done using a high accuracy pressure transmitters. The experimental investigations were used to measure and interpret the pressure drop data under static and dynamic conditions. The pressure is correlated empirically as a function of the design parameters. A good agreement was obtained between the measured values and the correlation predictions. This paper discusses mainly the importance of understanding pressure measurement in the process under two phase system of open cycle OTEC. These studies will be helpful to design a large scale OC-OTEC LTTD plant at Kavaratti of Lakshadweep Islands.

190 Ocean Engineering and Technology

Longterm shoreline changes along Kanyakumari coast using Geo spatial techniques ORAL OSICON2021/206 N. Rama Krishnan, J. Guru Prasath, P. Chandramohan Indomer Coastal Hydraulics, Chennai

The coastal zones take place at the interface between three major natural systems such as land, ocean and atmosphere of the Earth’s surface. Coastal processes operating at these three systems are the reason for shaping and maintaining the coastal zone. The interaction between these natural processes makes the coastal zone an extremely dynamic one. This coastal zone transfers the material from the land surface to the ocean system, with sediments eroded by rivers, glaciers etc., being moved to the beach ﬂoor. In some, accumulation of sediments may add to the land mass. The shoreline is where land meets the sea, and it is continuously changing. The shoreline, as zone of contact between a body of water and land, is an interface that continuously changing through time and space. While shoreline is the actual margin of two coasts includes areas below and above the water line. It is a broad transitional area in which terrestrial environments inﬂuence the marine environment and vice versa. The present study, an attempt was made to elucidate the accretion and erosion sites from multi temporal satellite imageries of Kanyakumari district coast, Tamil Nadu State over the period of 40 years (1990 to 2020) using Geo Spatial techniques. The various primary and secondary data been used namely, satellite imageries, Survey of India toposheet, existing coastal protection structure, coastal villages and socioeconomic data. Those data been processed by USGL Digital Shoreline Analysis System (DSAS) tool and Rate of shoreline change was studied based on End Point Rate (EPR) and Linear Regression Rate (LRR) methods in GIS softwares. The study gives a synoptic view of the degree of vulnerable threat to the entire coastal village of the district and also it helps in managing the threat to the entire coastal system. It provides the suitable locations for adaptation measurement and shore protection structures in the study area.

191 Ocean Engineering and Technology

Impact of future climate scenarios on Chloride ingress and Carbonation levels in coastal reinforced concrete structures ORAL OSICON2021/212 B Santosh kumar, S A Sannasiraj, K Murali Department of Ocean Engineering, IIT Madras

Climate change is creating emergencies in every sector, globally and locally. Coastal infrastructure is one and major of those that are experiencing severe impact due to changing climate. The deterioration mechanisms of structural elements or materials are becoming more rapid and creating huge loss to the functioning of the facilities. The present study focuses on effect of future climate scenarios (predicted by IPCC AR5) on deterioration process of coastal reinforced concrete structures. Prelimi- nary study on two berthing structures located in two different regions has revealed that the structural elements/materials were deteriorated more than that of the deterioration that could happen considering age of the structure.This study focused on understanding chloride content and carbonation levels in reinforced concrete in coastal region. Based on field tests (NDT) on berthing structures, a model study is conducted incorporating temperature changes right from the year of construction to the year 2100. The past studies stated that change in temperature will have significant impact on both deterioration processes. The present study has revealed chloride ingress is asymptotically increased towards year 2100 and with less difference between RCP scenarios 4.5 and 8.5. On the other hand, Carbonation too has significant impact considering temperature alone. However, the research is being carried out considering other atmospheric parameters like carbon dioxide levels and air salinity.

192 Ocean Engineering and Technology

Study of wave spectral characteristics in deep water region in the southern Bay of Bengal ORAL OSICON2021/214 R. Janani1,2, G. Latha1, M. Krishnaveni2, R. Venkatesan1 1National Institute of Ocean Technology, Chennai; 2Center for Water Resources, Anna University, Chennai

The spectral characteristic of waves in the deepwater region of southern Bay of Ben- gal is studied based on the OMNI (Ocean Moored buoy Network for the northern Indian Ocean) buoy (BD14 - 7N/88E) wave measurements for one year during 2017, made by National Institute of Ocean Technology, Chennai. The monthly averaged wave spectra are estimated to study the sea state conditions and interseasonal variations in the location. From the data analysis, it is observed that during the month of May the spectral energy density is high as compared to other months. This is due to the impact of severe cyclonic storm Mora which was formed over the southeast Bay of Bengal on 28th May 2017 and the system got intensiﬁed and moved towards the north- northeastwards and it made landfall on the coast of Bangladesh on 30th May 2017. The maximum signiﬁcant wave height observed during the cyclone period is 2.24m on 30th May 2017 and the maximum wind speed recorded is 17.2 m/s on 25th May 2017. However, the seasonally averaged wave spectra are calculated and it shows multipeak wave spectra are observed during the monsoon season (June, July, August, September), whereas during pre (February, March, April, May) and post-monsoon (October, November, December, January) seasons double peaks are dominating in this location. A comparative study for the measured wave parameters with Wavewatch III model results is carried out, and it shows a good correlation with the model results.

193 Ocean Engineering and Technology

Importance of Tide Gauge Observations to Identify the Multi-scale Sea Level Variability over Western Bay of Bengal QUICK ORAL Arkaprava Ray, Samiran Mandal, Sourav Sil OSICON2021/228 Ocean Analysis and Simulation Laboratory, School of Earth Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar, Odisha, India

Tide Gauge, one of the most important instruments of the ocean observation network, fitted with sensors, is used to capture the surrounding sea level. Many of the tide gauges are installed by the Survey of India, but presently the ESSO-INCOIS is taking care of 31 tide gauges around the Indian coast for real-time monitoring of the sea level height. This study mainly focuses on capturing different non-tidal signals over the western coast of the Bay of Bengal. The tide gauges observations during 2012-2014 at four stations - Ennore, Kakinada, Paradeep, and Garden Reach (data source: ESSO-INCOIS), have been used to investigate the variabilities at different scales. Gradual increase in tidal heights towards the northern bay and the seasonal variability of tidal heights for certain constituents have been identified in these observations. The propagation of the coastal KWs from the equatorial Indian Ocean to the western BoB shows the periodicity of 100-120 days. On the other hand, dominant signals of 30-90 days are observed in the BoB due to the monsoon ISOs and Madden Julian Oscillations. The 10-20-day oscillations are also seen with significant amplitudes on the north-western BoB due to the Quasi-Biweekly Oscillations. Such multi-scale variability can impact the sub-surface of the coastal ocean and the productivity of the region. It can also indirectly control the storm surge height during the landfall of any cyclones. Thus, the technology for observing the ocean is essential to understand the natural processes and introduce multi-scale variability in a numerical model for a better prediction along the coastal region.

194 Ocean Engineering and Technology

Shoreline changes of Devaneri coast, Tamilnadu, India ORAL OSICON2021/229 J. Sriganesh, A. Pradeep, S.A. Sannasiraj, V. Sundar Department of Ocean Engineering, Indian Institute of Technology Madras, Chennai, Tamil Nadu, India

Coastal infrastructure developments such as ports, nuclear power plants, desalination plants, fishing harbour, etc, and shore protections (seawall, jetty, groynes, etc) requires a proper understanding of the shoreline for sustainable management of the coast. This study focus on the long term shoreline changes along the Devaneri coastal village located between the latitude 12.650o to 12.652o N and longitude 80.208o to 80.209oE of about 4.0 kilometer north of Mahabalipuram shore temple, in the Chengalpattu district of northern Tamil Nadu state. Shoreline changes were analyzed primarily by field data collection in the study area for three years with a frequency of once a month during spring tide on which the coast experiences the highest high tide and lowest low tide level. The shorelines were demarked using the high accurate (less than a meter horizontal and vertical accuracy) Real-Time Kinematic Global Positioning System (RTK- GPS). The seasonal and annual shoreline changes were analyzed at 100m horizontal spacing seven (7) pre-defined shores fixed base stations and the results are presented here. Earlier this shore was protected for a 50m length rubble mound seawall (which still exists) and the present spring tide shoreline study enhances the present understanding with additional basic information.

195 Ocean Engineering and Technology

Challenges in Design of Intake Structure in Remote Islands ORAL OSICON2021/239 Suganya S1, Mounika Mallela1, Preethi Sekar1, Satya Kiran Raju Alluri2, M. V. Ramana Murthy2 1National Institute of Ocean Technology, Chennai; 2National Centre for Coastal Research, Chennai

Increased population and scarcity of freshwater resources have made desalination process a major source of freshwater in the remote islands of Lakshadweep. One of the major components is intake structure which collects sea water that needs to be pumped to the desalination plant for generation of fresh water. The sump or sea water intake is a gravity based hydraulic structure which has to be designed for very high lateral loads from breaking waves, thus requiring very high self- weight for stability. However, there is a lack of infrastructure for launching of the sump in remote islands. The sump has to be therefore constructed in shore and floated in the lagoon region. The depth of lagoon is minimal and therefore the weight of the sump is to be minimal for the available draft. The sump is to be partially constructed and floated from the casting yard, to the location of installation and then progressively completed. Therefore, there is a conflict in the design requirement where stability requires more weight while floatation requires minimal weight. This paper depicts the structural and floatation challenges encountered and design solutions adopted for the sump for the Low Temperature Thermal De- salination (LTTD) plant in Kalpeni, a remote island of UT Lakshadweep. In the present study, structural design of intake structure has been carried out using a Finite Element Package. Design considerations include various load combinations of extreme events and various measures to ensure stability against overturning and sliding. An investigation has been carried out to determine optimal shape of intake structure which will minimise the wave force acting on it and ensure in-place stability. The aspect ratio of the sump is decided based on the required draft and for successful floatation of the sump. A floatation analysis is also carried out to determine its stability during floatation. A sump of 12 × 9 × 9 m with partially inclined walls from a height of 7.5 m had been towed with a draft of 2.5 m in Kalpeni island lagoon. The sump has been successfully installed in 5m water depth and is now functional in Kalpeni Island.

196 Ocean Engineering and Technology

Monopile Supported Trestles for Intake and Outfall Systems at Remote Islands ORAL OSICON2021/241 Sondi Sudheer1, Suganya S1, Mekala Madhu1, Maddu Sagar1, Satya Kiran Raju Alluri2, M. V. Ramana Murthy2 1National Institute of Ocean Technology, Chennai; 2National Centre for Coastal Research, Chennai

Intake and outfall structures are generally associated with an approach trestle to conduct the water onshore. Conventionally, two row piles are utilized for the construction of trestle due to easy construction methodology. These foundations for the bridge must not only support the entire weight of the bridge but also the lateral loads due to high breaking waves, water level variations, prevalent currents and available soil conditions. However, single row piles can also be designed for the trestle. This is not generally opted in the construction industry due to the uncertainties associated with the gantry loading and movement during installation. It is generally understood that single row piles are economical while the stability of the gantry is assured in two row piles.

A comparative analysis has been made between single and two row piles as foundation for remote locations where weathered rocks are present. These locations have trestle extending well beyond the breaker zone, as is the case in most intake structures. This assures that there is only a selected weather window available for construction and therefore, the time required for installation plays a major role. This study analyses both the construction and operational loads that come on to the structure and the stability of the piles for the same and unequal gantry loading. A Finite Element Package has been used to study the stresses and stability of members as this design has a combination of steel and concrete. The entire setup is designed as 1D beam elements and the soil is modelled as springs. The stresses induced in piles, pile caps, welds, bracings and gantry are analyzed.

The time of completion and the economic benefit for both configurations are arrived at. From the study, it is clearly seen that the construction time in the case of single row piles is more effective provided necessary precautions are taken to avoid instability during implementation.

197 Ocean Engineering and Technology

Performance of Monopile Platforms during Service Life ORAL OSICON2021/242 Mounika Mallela1, Preethi Sekar1, Satya Kiran Raju Alluri2, Rajesh Katyal3, M. V. Ramana Murthy2 1National Institute of Ocean Technology, Chennai; 2National Centre for Coastal Research; 3National Institute of Wind Energy

The design of any structure is based on the codal provisions laid based on years of experience and experiments. However, in cases of marine structures, designs available are based on the oﬀshore platforms that are constructed with design life of at least 25 years. For structures that are constructed for a short duration, these assumptions might be overestimating the loads acting on the structure. In some cases, there are no standard provisions available for structures situated in Indian subcontinent. A monopile with design life of 5 years installed in the Gulf of Khambhat as an observation platform, is taken as case study. Rotation is critical in this location due to serviceability requirement of the LiDAR.

In this paper, variation in the utilization ratio and serviceability limit are analyzed for the monopile through the design life of 5 years by studying the effects of marine growth, scour and corrosion. Scour removes the soil layers and reduces the support thus increasing the deflection. Due to corrosion, the thickness of the pile keeps deteriorating and therefore the stiffness of the pile also comes down. The effect of marine growth is two-fold. The roughness of the pile increases due to marine growth and the projected area over which wave load is applied is also increased due to increase in thickness due to marine growth.

From the study, we can see that the development of marine growth is not gradual for the first one year and attains its maximum at around 3 years. Scour is an immediate phenomenon and 63% of scour develops in two weeks and by 6 months almost all scour is developed. Therefore, the scour value is constant for all five years. The corrosion keeps continuing as the monopile ages. The marine growth has maximum impact on the utilization ratio and rotation at the end of 5 years. The combined effect increases the rotation by 15% in the first year but attains an increase of around 25% in the fifth year. A better understanding on these phenomena will lead to a much more economical design for structures specially with lesser service life.

198 Ocean Engineering and Technology

A statistical study of seasonal underwater noise as a function of wind and marine traﬃc ORAL OSICON2021/251 Elizabeth shani N. X.1,2, Nimmi R. Nair1, R. P. Raju1, R. Sajeev2 1Naval Physical and Oceanographic Laboratory, Ministry of defense, Thrikkakara, Kochi; 2Department of Physical Oceanography, School of Marine Science, Cochin University of Science and Technology, Kochi

The variation of noise with depth is an essential parameter for design and deployment of SONAR systems. Various studies have shown that shallow water ambient noise exhibits high spatio-temporal variability and depends on prevailing sound speed profile (SSP) and bottom properties. This makes the modeling of noise level (NL) and its spatial correlation a challenging endeavor. Hence, Statistical parameters derived from noise measurements along with oceanographic parameters are useful to describe the spatio-temporal variation of NL. Statistical parameters of noise data like mean, median, standard deviation (std), probability density function (pdf) and its histogram representations are used here to analyze the noise profile with depth and its seasonal variation. Noise measurements were carried at three shallow water stations off west coast of India in three consecutive years 2015-2017, during summer (March-May) and winter (Nov- January). Noise was measured in silent ship regime, at four predetermined depths from 10 to 50 m using omnidirectional broad- band hydrophones. Alongside sound speed profiles, wind speed from onboard AWS (Automatic Weather Station) and marine traffic from AIS (Automatic Identification System) were also collected.

Statistical analysis was carried out in two spectral regions, Traffic (50- 500Hz) and wind (2-5 kHz) dominated noise field, using two temporal windows 500 ms and 1s. Then the pdf estimated using normal distribution, was overlaid on the histogram of NL expressed as PSD. Spectral analysis shows, in traffic dominated spectrum normal distribution yields a poor fit to data whereas it was found to be appropriate for wind noise region. Spectral comparison also shows that Mean, Median and std were high in traffic noise part. Another prominent feature observed in statistical analysis is that in normal conditions as depth increases position of mean/median shift towards the lower NL value and it is consistent in both frequency domain and temporal windows. The seasonal comparison shows that in winter season-SSP with a duct,deeper depths are seen to have higher mean/median. Using an appropriate propagation model it was found that the prevailing SSP has allowed the sources from longer distances to contribute towards the total noise spectrum through ducted propagation.

199 Ocean Engineering and Technology

Seasonal sediment characteristics analysis of Kandla creek and Gulf of Kutch ORAL OSICON2021/295 D. Nandhini, J. Sriganesh, K. Murali Department of Ocean Engineering, Indian Institute of Technology Madras, Chennai

The coasts of Gulf of Kutch (140km length and 70km width) located in the Gujarat state of north western extreme end of India is with highly irregular configurations with a number of islands, mud flats, creeks, bays, marshes, reefs, tidal flats, about ten (10) small and large ports along with many other natural and anthropogenic morphological features. The Kandla creek length of 9.0km located on the north of Gulf of Kutch between the latitude 22o 58’ to 23o 03’N and longitude 70o 13’ to 70o 14’E which is about 100 to 110km east from the mouth of Gulf of Kutch. This Kandla creek hydrodynamics and morphodynamics are mainly influenced by the river discharges in the upstream and macro tides (ebb / flood) in the downstream. These two constant natural forces responsible for the inevitable physical modification and sediment movements along with distributions. Understanding sea bed sediment characteristics is one of the most fundamental parameter for any sustainable coastal development and also the seasonal seabed sediments variation study is another important requirement for the enhancement of the knowledge about the seabed sediment characteristics which can be achieved only through extensive in-situ measurements and lab analysis learning. In this study, the sea bed sediment characteristics of the three Zones, namely 1. Kandla Creek (5.0km), 2. Kandla Creek Mouth (2.5km) and 3. Gulf of Kutch (near to the Kandla Creek about 4.5km) were studied by analyzing the particle size and its distribution pattern from eight (8) different depth (-5.0m to -18.0m) locations for the three seasons of one year. The seabed sampling by grab sampler equipment and the grain size analysis was carried out in the IITM laboratory. The samples were collected during (a) March to June 2019 (Pre-Monsoon) (b) July to October 2019 (Monsoon) and (c) November 2019 to February 2020 (Post-Monsoon) at Kandla Creek (3 samples with 2.5 km interval), Kandla Creek Mouth (2 samples with 1.0 km interval) and Gulf of Kutch (3 samples with 2.0km interval). This study examine the distribution of sediments in the three zones through grain size analysis which convey that the Zone 1 (Kandla creek) with coarser sediment (sand), Zone 2 (Mouth) with finer sediments (sandy clay & silt) and the Zone 3 (Gulf of Kutch) with silty loam.

200 Ocean Engineering and Technology

Conductivity sensor for marine applications based on capacitive coupling technique ORAL OSICON2021/318 Srinivasan R., Boby George, Tata Sudhakar and Ramadass G. A. National Institute of Ocean Technology, Chennai

Conductivity is the intrinsic property of sea water from which the salinity can be determined and the measurement of salinity is a regulatory requirement. This work is aimed at developing a conductivity sensor for Ocean Observation applications. The concept of capacitive coupling is attempted in combination with contact electrodes while designing the conductivity probe which eliminates the polarization and lead or electrode contamination issues associated with regular electrode type conductivity measurement methods. This approach also confines fixed the cell constant and hence the defined current path in the probe. In this method, the probe design combines the advantages of contact type and capacitively coupled method. The probe has three circular contact type electrodes (exciting electrode, receiving electrode and dummy electrode) and two circular capacitively coupled voltage electrodes (dielectric coating over the metal electrodes). The contact type electrodes act as the current electrodes similar to the four electrode method; Contactless electrodes act as the potential electrodes. When the exciting electrode is excited, the current will start flowing into the water and collected by the receiver electrode. If used for conductivity measurement of sea water the entire probe will be surrounded by sea water and insulator over the electrode will avoid direct contact of electrode with surrounding water. In such an application, dummy electrode will make sure that no current flows in the surrounding water and ensures that the path of current includes only the water inside the pipe between the excitation and receiver electrodes. The insulated voltage electrodes are metal electrodes coated with a dielectric material. Thus a capacitance is formed between the metal electrodes and the outer surface of water in the tube.

201 Ocean Engineering and Technology

Development of Autonomous Underwater Proﬁling Drifter ORAL OSICON2021/321 Muthvel P., Sarojani Maurya, Tata Sudhakar National Institute of Ocean Technology, Chennai

This paper presents an Autonomous Underwater Profiling Drifter (AUPD) which uses the buoyancy change for its heave motion in ocean column for underwater observation. An AUPD float has been developed by National Institute of Ocean Technology (NIOT) to observe the in situ temperature and salinity of the ocean. AUPD changes its buoyancy to profile up to the depth of 2000m using a Variable Buoyancy Engine (VBE) of 250 ml capacity. The main components of the AUPD are Variable Buoyancy Engine (VBE) to perform descend and ascend, CTD sensor to sample the ocean column, control electronics to schedule various phase of the mission cycle and satellite telemetry system to send profile data to the base station. The profile data is collected by a pre programmed mission and is transmitted to shore using ARGOS satellite communication. The AUPD float was demonstrated in Arabian Sea in 2012–2014. The paper reports on the design, development and field trial of AUPD float.

202 Ocean Engineering and Technology

Sensitivity analysis of wave hindcasts for the design criteria for engineering applications ORAL OSICON2021/323 Muhammed Naseef T, J. Rajkumar, Basanta Kumar Jena National Institute of Ocean Technology, Ministry of Earth Sciences, Chennai

An accurate information about wave characteristics and climatology is required for safe designing or maintenance of coastal and offshore marine structures and activities. Climatology of Indian Ocean surface waves possess a unique nature compared to other ocean basins. The National Institute of Ocean Technology (NIOT) had released a technical criteria wave atlas in 2014 which was well appreciated by both scientific and industrial community. It was used 15 years of hindcasted data simulated by MIKE–21 spectral wave model developed by the Danish hydraulic institute. Now, The NIOT planned to release an updated version of the atlas with improved simulation capability as well as more accurate wave information. The proposed atlas uses higher resolution (0.1o × 0.1o) wind input data from ECMWF operational archive. The previous wave atlas was not included islands in the simulation domain whereas both Lakshadweep and Andaman Islands were included in the present study. Previous studies indicate swells from southern ocean (from southern region of 50–60oS) influence the wave climate in the North Indian Ocean. Hence a sensitivity analysis was carried out to know how the selection of domain extension and model boundary conditions impact the quality of hindcasted wave data. A total of 6 domains are considered in the present study considering open/closed boundary conditions and 0oS, 20oS, 40oS and, 60oS domain extensions. Significant wave height (swh), mean wave period (mwp) and mean wave direction (mwd) parameters were used to compare with the wave characteristics during 2017 at two deep water observations- Arabian Sea (AS) and Bay of Bengal (BoB) location each. The result indicates that improved correlation for swh (0.916 m compared to 0.894 m) and mwp (0.708 s to 0.892 s) but slight reduction in mwd when considering the 60oS domain. The percentage difference in the maximum observations also indicate the improvement in the hindcasts. An under estimation of 11.73% in swh is reduced to 5.87% at BoB location. A tropical cyclone were present in the AS during the study period, so there is no significant improvement in the percentage difference.

203 Ocean Engineering and Technology

Design and Development of automatic open sea hybrid submerged ﬁsh cage system ORAL OSICON2021/325 S Muthukumaravel, V Gowthaman, J Santhanakumar,S Rajaguru, G Dharani National Institute of Ocean Technology, Ministry of Earth Sciences, Chennai

Development of offshore open sea cage culture is a new way of providing employment and good revenue for fishermen transferring from fish capture to aquaculture. The open sea fish cage culture system is designed to reduce the deep sea (burden of going long way into sea) fish catching for fisher community by increasing the yield of fish growth at offshore areas near to their convenient places with reduced resources and manpower. Mission Mariculture–2022 aimed at meeting the fish demand of 20MT by 2022-23 under Pradhan Mantri Matsys Sampasa Yojana (PMMSY) supporting ”Blue revolution”. The Blue Revolution, with its multi-dimensional activities, focuses mainly on increasing fisheries production and productivity from aquaculture and fisheries resources, both inland and marine besides strengthening of post-harvest fishery infrastructure facilities. This will also fulfil the gap to achieve the additional fish production of 5.0 million tone by the end of 2022. With the Mission Mariculture -2022, it is proposed to promote mariculture including open sea cage culture in all maritime states and UTs on priority basis with active participation of fisherman. Hence it is necessary to develop various technologies on aquaculture to have sustainable fish production. In these, the one of the technology being the open sea cage farming through which the country can enhance the fish production only under marine sector from the present contribution of 32% to 60%. In this paper, it highlights the technologies being developed and demonstrated and it’s up gradation with higher capacity being taken up to meet the marine sector contribution. We have tested Spar type submerged fish cage system with unique type water ejector based feeder system with automatic Instrumentation and control system for its submergence and floating operation using both pumped buoyancy mechanism and pneumatic pumped system using DAQ. The user can control cage submergence depth, velocity by timing sequence and floating operation from land using GSM (Global System for Mobile) communication technology. Our developed spar type submerged fish cage has redundancy system in operation point of view to achieve the reliability and to meet any critical situation to bring the cage to the surface at any point of time. This method is considered to be novel design in the aquaculture field. This submerged fish cage has central spar which has fitted submersible pump at the bottom as well as pneumatic connection at the top to send the compressor air into it. The spar is connected to centre octagonal ring using PP rope in such a way that the central spar is tightly kept upright on these rope without any elongation. This central spar is used to controlling the buoyancy using ballasting seawater in it using both pumped buoyancy control with help of submersible pump and for pneumatic pumped system, a compressor air is sent to central spar to displace the water out by ensuring in pulsed flow so that system will be surfaced in a smooth manner

204 Ocean Engineering and Technology

Performance of C Proﬁler during the sea trial ORAL OSICON2021/327 V Gowthaman, G Shiva Prasad, Tata Sudhakar National Institute of Ocean Technology (NIOT), Pallikaranai, Chennai

C–Profiler is an indigenous underway sea profiling float which collects conductivity, temperature and depth (CTD) data along with position while ship is on the move. These measurements (CTD) are important for study of fresh water mixing in shallow regions, to estimate parameters effecting climate changes, to study vertical motions of sea water due to density changes and temporal changes of conductivity and temperature, for sub- mesoscale studies and to estimate velocity of acoustic signals underwater. The C–Profileris an ocean observation system with CTD sensor which is instrumented in a tow fish, moves up and down with the help of automated tow winch in between reconfigurable minimum and maximum depths. The advantages of C profiler include, without lifting the probe on deck from sea surface, real time on site decisions can be made for specific profiling depth and track, for data retrieval from the probe. Sensor heads are exchangeable which enables to collect various ocean parameters without extra profiler. This system creates a data file set for each profile that contains GPS data (location) and CTD data, distance between two consecutive profiles and angle of vertically with normal.Performance of the C-Profiler system was tested in two trail cruises, conducted on 7th May and 7th June 2019 for 100m depth. The system captured data sets from sea for each profile and two real time plots were made from that.Data comparison was done with the on-board standard CTD with correlation graphs and we found close match.

205 Ocean Engineering and Technology

Eﬀect of internal tides on acoustic propagation in the Central Arabian Sea QUICK ORAL Merin C. A., Nimmi R. Nair, AnilKumar K. OSICON2021/331 Naval Physical Oceanographic Laboratory, Kochi

The underwater acoustic propagation is affected by internal tides in the ocean. This study is based on the analysis of the CTD and ADCP data collected at Central Arabian Sea (CAS) for one year. A sharp gradient in Mixed Layer depth (MLD) and a continuous Sea Surface Temperature (SST) variation is observed in the time series data of CTD, between seasons. To cite, the sound speed gradient (µ) decreases sharply from 0.4 m/s to 0.1 m/s per meter with depth, as the MLD varies from 65 m to 150 m, in the month of December. This gradient can affect the acoustic propagation in this area. From the spectral analysis of current data at CAS, in different timescales (i.e. ∼7 days up to 6 months) it is observed that semidiurnal wave (1/12cph) was a major component. Apart from that, a diurnal (1/24cph) and a high frequency component (∼1/6 cph) is present in the velocity spectra. The N frequency peaks the beginning of the thermocline, and settles to a value of 3-5 cph. The N frequency has a peak value of 21.2 cph in NE monsoon in the month of December, and is 10-20 cph, during other months. The N frequency spectrum shows a similar trend as that of the velocity spectrum. A set of range dependent sound- speed profiles is generated corresponding to the drifting speed of bulk, induced by internal waves with an estimated speed of ∼50 cm/s. A normal mode acoustic model is being used to see the effect of internal tides.

206 Ocean Engineering and Technology

Numerical study of wave transmission and interaction with submerged artiﬁcial reef at Puducherry coast ORAL OSICON2021/332 Satya Kiran Raju Alluri1, Ramana Murthy M V1, Sannasi Raj S A2 1 National Centre for Coastal Research, Ministry of Earth Science, Narayanapuram, Chennai; 2 Department of Ocean Engineering, Indian Institute of Technology Madras, Chennai

Coastal erosion due to either natural or human intervention at coastal area is heavily impact the social and economic aspects of the people. Coastal erosion can be miti- gated by providing protection measures near the coast to reduce shore ward currents which has the major contribution for coastal erosion. These protecting measures are cite specific and in the range from natural mangroves to structures such as sea walls, groins and artificial reefs. Ministry of Earth Science, India, implemented and com- missioned the coastal protection measure at Pondicherry to restore and protect the lost beach with an artificial reef. The wedge-shaped artificial reef constructed and launched by MoES helped in formation of new beach at Puducherry coast. Post construction studies are carried out for monitoring the performance of the reef which will help in design optimization and improve the efficacy of the structure for beach protection. This can be done by measuring the beach profiles and bathymetry near the reef periodically to estimate the quantity of beach formation and construct the numerical models for the site conditions to study wave interaction and sediment transportation. In the present study numerical models are developed using Computational Fluid Dynamics (CFD) based open source tool OpenFOAM to investigate the wave transportation near the wedge shaped reef and wave interaction with the reef. Multi- phase modelling with turbulence models is employed to study the wave impact and breaking near the structure. The default turbulence models available in OpenFOAM are not considered the density variation between water and air phases in the multi- phase modelling which results in excessive wave height damping due to increase in turbulent viscosity as simulation progress. To mitigate this effect, the modified κ - ε and κ - ω and SST models which are suitable for multi-phase modelling is employed in the present simulations and compared their performance.

207 Polar Science & Cryosphere studies (PSC)

Session Chairman

Dr. M. Sudhakar Former Director, Centre for Marine Living Resources & Ecology (CMLRE), Kochi, Kerala

208 Polar Science & Cryosphere studies (PSC)

Invited Talk

INVITED TALK: Decadal Indian Observational Campaigns in the Southern Ocean and the Future perspectives

Dr. N. Anilkumar

National Centre for Polar and Ocean Research (NCPOR), Goa Polar Science & Cryosphere studies

Assessing the status of glaciers in upper Jhelum basin of Kashmir Himalayas using Sentinel–2 earth observation data QUICK ORAL Syed Towseef Ahmad OSICON2021/4 University of Kashmir, Srinagar, Jammu and Kashmir

Climate change, a global challenge of our time has severely impacted mountain glaciers and in particular glaciers over the Himalayas, causing their mass loss at an accelerated rate. The rapidity of the process has a direct impact on hydrological system of the region. The conventional field-based experiments are difficult to conduct in Himalayas arguably so because of tough terrain and harsh weather conditions, an impediment in the process of monitoring glaciers in the region. However, Satellite based remote sensing along with GIS offers a potential mode for glacier monitoring and assessment. The Jhelum basin, in the North-western Himalayas with its temperate Mediterranean climate contains numerous glaciers. This study presents an updated glacier inventory of 2018 for the study region, and documents some 307 glaciers, which range in size from 0.01 to 10.55 Km2 and occupying the glaciated area of 102.5 Km2. All the glaciers are located between 3500 and 5000 m asl. About 70% of the glaciers are located in the elevation zone of 4000 to 4600 m asl and most of them are valley and cirque type. The total ice reserves contained in the Jhelum basin are estimated to be 3.75 Km3 with the mean volume of 0.012 Km3. Similarly the average depth of the glaciers was calculated as 20.6 meters. The minimum and maximum depths are shown by the glaciers of Lidder watershed with the thickness of 2 m (G075359E34206N) and 96 meters (G075336E34167N) respectively. The results of this study would help to strengthen the existing database of glaciers, which is crucial for the assessment and management of water resources and the hazards associated with the glaciers.

210 Polar Science & Cryosphere studies

Inventory and spatio–temporal dynamics of glacial lakes in Dibang river basin of Eastern Himalayas using combined approaches of Remote Sensing and GIS QUICK ORAL Rayees Ahmed OSICON2021/6 University of Kashmir, Srinagar, Jammu and Kashmir

Increasing warming trend has intensiﬁed the melting of glaciers viz-a-viz glacial lake formation and development in the Eastern Himalayas. Consequently increasing the possibility of Glacial Lake Outburst Floods (GLOFs) in the region, which have the potential to severely impact water resources, agriculture and Hydropower projects in the neighborhood areas. The present study used Sentinel-2A (2020) and Landsat 7 ETM+ (2000) data scenes to prepare a detailed and updated inventory as well as to analyze the spatio-temporal dynamics of glacial lakes in Dibang River basin. The study revealed that, in 2020 there are 335 glacial lakes in the study area with size greater than 0.01 Km2. Number of lakes has increased from 281 in 2000 to 335 in 2020 with a growth rate of 16.11 percent. Area has also increased from 41.48 Km 2 in 2000 to 44.48 Km2 in 2020 with a growth rate of 6.74 percent. Hence, lake number and area has shown a considerable increase from 2000-2020. The lakes that are fed by glaciers have increased from 190 (27.51 Km2) to 221 (29.78 Km2) and the lakes not-fed by glaciers have increased from 91 (13.99 Km2) to 114 (14.69 Km2) over the study period. All the glacial lakes are situated at an elevation ranging between 2400-5200m asl with a mean elevation of 3212m asl. About 70% of the total glacial lake number and 68% of the total area are present in the elevation zone of 3500-4500 m asl. Depth and volume of glacial lakes was calculated using empirical formulas. The ﬁndings reveal that with the increasing number and area, the lake volume has also increased probably because of global warming. This study can serve as reference database for the studies pertaining to glacier melting, climate change and glacial lake expansion, GLOFs and water resource management. Further, it is a step towards regular monitoring and management of rapidly expanding glacial lakes in the Dibang River basin.

211 Polar Science & Cryosphere studies

Sincere Feeding and Utmost care to Brutal Cannibalism of Self Brood in South Polar Skua in Schirmacher Oasis, Antarctica ORAL OSICON2021/55 Shivaji P. Chavan Department of Zoology, School of Life Sciences, Swami Ramanand Teerth Marathwada University, Nanded, India

South Polar Skua (Stercorarius maccormicki) is breeding endemic mostly to periph- eral Antarctica. Schirmacher Oasis (SO) is a snow free area in East Antarctica having 34 sq. km. area was selected by South Polar Skua (SPS), was study area. By point count method using ’MAITRI’ station of India as reference point 11 active nests of SPS were identified. The nest survey for the SPS breeding activity monitoring was conducted by walk in the study area. Harsh weather conditions and very rough rocky terrain with scrap stones, boulders, low valleys and hills of SO during austral summer of Nov. 2019 to March 2020. The nest site selection was same but the nesting was well defined sequential activity. It is first record to locate exact nest sites of SPS 11 breeding pairs with data on lat. long. coordinates in SO. Land Locked Lakes (LLL) was selected for nesting by SPS instead of Pro-glacial lakes (PGL) and Epi-shelf lakes (EPL). The clutch size was 2-3 eggs/nest. The average value of breeding indices noted includes hatching success (65.2%), brood reared to advanced chick stage (13.13%) by regular and sincere feeding efforts by both the parents. The contribution of male SPS in all the nests for foraging trips was >70% compared to the efforts by female SPS. Both the parents were involved to demonstrate the feeding process using regurgitated food at nest site. Average time for foraging trips was recorded. The dominance of early hatched chick on late hatched was found, that result into forced escape of later in to 50-100 ft. away from nest area was found. Escaped chick was used as reserved food and hence maintained live to cannibalize at any required time of food need. The reasons for the 0.0% breeding success was due to 100% self cannibalism by their own parents are discussed.

212 Polar Science & Cryosphere studies

Upperocean mixing during austral summer in the Prydz Bay region of East Antarctica ORAL OSICON2021/85 Jenson V. George, Sabu P., Aditya Narayanan, N. Anilkumar National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Vasco-da-Gama, Goa

Mixing and heat flux rates observed in the Prydz Bay region of East Antarctica during the Indian Expedition to Southern Ocean 2020 are presented. The observations cover the shelf and open ocean regions of Prydz Bay during the summer of 2020. The thermocline observed in the open ocean region constitutes the upper part of the temperature minimum (Tmin) layer. The Tmin layer is a remnant of the winter mixed layer. Mixing between the Tmin layer and the newly formed mixed layer in the late summer is essential for the seaice formation in the subsequent winter. Diapycnal mixing in the thermocline (upper part of Tmin layer) results in downward heat flux from the mixed layer and cools down the mixed layer. Mean heat flux values in the thermocline depth were -2 W/m2 at the shelf region and -1.8 W/m2 in the open ocean region. However, it reached up to ∼-10 w/m2 occasionally. All observations in the thermocline suggest that the vertical mixing scales inversely with stratification. The stratification is decided by the sea ice melting and mixed layer warming rate during the summer. The associated strengthening of thermocline stratification has significant consequences for the mixing and heat fluxes. In the mixed layer, the turbulent kinetic energy dissipation rate was enhanced to values greater than 10−6 W/kg and reduced to 10−8 W/Kg at the thermocline region.

213 Polar Science & Cryosphere studies

Arctic sea-ice variability using an Earth system model QUICK ORAL Suraj Ravindran1, Vimlesh Pant1, A. K. Mitra2, Avinash Kumar3 OSICON2021/107 1Centre for Atmospheric Sciences (CAS), Indian Institute of Technology (IIT), Delhi; 2National Centre for Medium Range Weather Forecasting, Noida, U.P. 3National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Goa

The recent decades have witnessed an unprecedented decline of arctic sea-ice extent and thinning of ice cover which has a significant impact on the global climate system. This change in the Arctic dynamics will affect the ocean physical and biogeochemical parameters. Here we explore the variability and future projections of sea-ice parameters like sea-ice heat content, sea-ice concentration, sea-ice thickness, sea surface temperature (SST) and salinity in the Arctic Ocean (AO) using an ensemble of simulations for a time period of 1850-2100 from the ‘Community Earth System Model’ (CESM2- WACCM), which is a part of the sixth phase of the Cou- pled Model Intercomparison Project (CMIP6). The regional differences are observed for the various sea-ice parameters over the seven marginal seas of the AO. The sea surface temperature (SST) has higher temporal variability in the Barents Sea, Beau- fort Sea and the Chukchi Sea in September, which confines to the Fram Strait and the Barents Sea regions in March. The SST is projected to increase by 6oC over the Chukchi Sea by the year 2100. The maximum difference in sea-ice heat content ( 4.5 Ö 108 J m−2 ) is obtained in the East Siberian Sea, central AO, and along the east coast of Greenland in March. In response to sea-ice melting, a decline in sea-ice thickness and reduction of sea surface salinity up to 2.5 psu is noticed in the future relative to the present climate in some parts of the AO. The roles of advection of warm Atlantic water, wind-driven mixing, and surface heat fluxes are discussed in the context of the sea-ice variability.

214 Polar Science & Cryosphere studies

Sea-ice in the Weddell Sea sector of West Antarctica: Insights from ocean-atmospheric forcing QUICK ORAL Juhi Yadav, Avinash Kumar, Rahul Mohan OSICON2021/114 National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Goa

The Weddell Sea is susceptible to the ongoing climate change and experiences a reduction in an overall increase in the sea-ice extent (SIE). The nature of sea-ice in the Weddell Sea is largely associated with its geographical setup that determines the seasonal and decadal sea-ice variability. The study analysed long-term sea ice-ocean-atmosphere variability and trends (1979-2019) based on satellite and reanalysis measurements. The result shows the expansion of yearly SIE is 2.5±3.5 × 103 km2yr−1 with a significant increase in the austral summer (12.4±4.6 × 103 km2yr−1), whereas a decrease in the spring SIE (-4.8±5.0 × 103 km2yr−1) over the last four decades. Seasonal sea-ice concentration (SIC) variations in the Weddell Sea are associated with latitudinal thermal differences and westerlies intensification, culminating in the weakening or strengthening of the Weddell Gyre. The SIC recorded significant positive trends in the western and eastern parts of the Weddell Sea during the austral summer and autumn, respectively. These changes are consistent with the prevailing wind patterns and Weddell Gyre intensification in the respective seasons. During the austral winter and spring, significant negative SIC trends (north of 65oS) were recorded due to the easterlies intensification and weakening of the Weddell Gyre. While, the significant positive trends observed along the coast are linked with the easterlies intensification and sea-ice advection. Composite analysis reveals that the SIC variability is related to the sea surface temperature (SST) during austral summer and spring, whereas SST and net heat flux (NHF) both regulate the SIC in the Weddell Sea during the austral winter and autumn. The positive Southern Annular Mode (SAM) is associated with an increase in sea- ice during austral summer, while sea-ice decreases during the winter in the Weddell Sea. The present study reveals a strong relationship between the sea-ice variability and ocean-atmospheric forcings, but these relationships are not constant over time; therefore, continuous monitoring is required.

215 Polar Science & Cryosphere studies

Mixotrophic plankton population and Synechococcus distribution in waters around Svalbard, Norway during June, 2019 ORAL OSICON2021/125 Jane T Bhaskar1, P.V. Bhaskar, Shridhar Jawak2 , R Jyothibabu3 1National Centre for Polar & Ocean Research, Headland Sada, Vasco-da-Gama, Goa ; 2SIOS Knowledge Centre, Postboks 156, 9171 Longyearbyen, Norway 3National Institute of Oceanography (Regional Centre), Kochi, Kerala

In order to understand the influence of summer conditions (extended daylight, warmer temperature, increased meltwater influence, increased suspended load and nutrient chemistry) on the distribution of phytoplankton (diatoms & flagellates) and picoplankton community in the surface waters off Svalbard, samples were collected from 6 locations around Svalbard. Additionally, satellite data was obtained for surface temperature, chlorophyll a (chl a) and total suspended mass (TSM). Stations Gn˚alodden (S1), Bellsund (S4), Open Ocean (S5), and Magdalenefjorden (S6) were along the western coast while stations Storfjorden (S2) and Western Storfjorden (S3) were on the eastern side of Svalbard and open to Barents Sea. Phytoplankton abundance ranged from 4 to 49 × 103 cells L−1 and were dominated by dinoflagellates such as Perdinium, Protoperidinium, Dynophysis, Gyrodinium, Gymnodinium and Torodinium species while diatoms (Navicula) were found only in colder polar waters (S5 and 6). Flowcytometry data showed the predominance of Synechococcus sp. and its abundance varied from 0.8 × 105 cells L−1 (S5) to 4.3 × 105 cells L−1 (S4). The distribution of Synechococcus was positively correlated to nitrate (r= 0.838) and chl a (r=0.915) while phytoplankton abundance had no correlation with chl a or nitrate. A weak positive lineartrend between Synechococcus and TSM suggests that melting of glaciers and influx of land run-off may be playing some role in increasing the picoplankton load in these waters. The predominance of mixotrophic dinoflagellates along with ciliates like Strombidium in these waters suggest that grazing of picoplankton as well as bacteria might fuel their carbon demand. Our data reflected post-spring bloom conditions wherein Synechococcus were the dominant primary producers and microbial loop might play an important role in sustaining the mixotroph population.

216 Polar Science & Cryosphere studies

Inter-annual Variability Of Sea Surface Temperature in the Indian Sector Of Southern Ocean during the Austral Summer ORAL OSICON2021/166 Antony P Thomas2, P. Sabu1, Subeesh M.P1 1National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Goa; 2Department of Physical Oceanography, Kerala University of Fisheries and Ocean Studies, Kochi

The present study was an attempt to understand the inter-annual variability of Sea Surface Temperature (SST) in the Indian Sector of the Southern Ocean (ISSO) during austral summer for the period 1994-2018. The study was also attempted to understand the influence of climatic events such as SAM and ENSO on SST variability in the ISSO. Large SST variability was noticed in the ISSO during some of the years. It is found that the eastern and western regions of the ISSO showing different trends in SST variability. The western region of the ISSO showed a weak warming trend than the eastern region during the period 1994-2018. This contrasting SST trend was also observed in the mixed layer, heat content and water column stability. The net heat flux variability during the above years did not explain the large variability observed in the SST. However, air temperature showed a strong positive correlation with the SST. In accordance with SST, large shifts were also noticed in the frontal positions of ISSO. It is observed that the SAM has a significant role in the SST variability. During positive SAM years, westerly wind belts with maximum wind speed were observed near the coastal regions of Antarctica. In response to this, equatorward Ekman transport was also observed. The sea-ice concentration also showed positive anomalies in Antarctica during SAM years. The anomalous sea-ice concentration and the northward Ekman transport of the cold waters from the coast of Antarctica could be the possible reason for the SST variability observed. Further, the EOF analysis confirms that SAM is the dominant climatic mode event in the ISSO which plays a major role in the SST variability of this region.

217 Polar Science & Cryosphere studies

Polar processing and Chemical ozone loss in the Exceptional Arctic winters of 2011 and 2020 QUICK ORAL R. Roy, J. Kuttippurath, D. Ardra, P. Kumar, S. Raj OSICON2021/202 1CORAL, Indian Institute of Technology Kharagpur, Kharagpur; 2Department of Physical Oceanography, Cochin University of Science and Technology, Kochi

The Arctic winters are distinct compared to the Antarctic winters due to the highly variable polar vortex. These instabilities are attributed to the frequent tropospheric planetary wave forcings in the northern hemisphere. As opposed to the usual observations, the mean heat fluxes and wave forcings were very small in the 2011 and 2020 winters. The minimal forcings could be accredited to the westerly phase of quasi biennial oscillations (QBO) and the absence of El Niñoforcing (ENSO) during the winters. These factors might have influenced the strength of the polar vortex by subsiding the strength of planetary scale waves. Apart from these other components such as the sea surface temperature (SST) forcings and the Arctic sea ice concentration (SIC) could influence the vortex stability. We examine the meteorology and ozone loss that occurred in two unusually cold Arctic winters; 2011 and 2020. These winters exhibited severe ozone depletion as opposed to the other Arctic winters. The analysis of temperature, zonal wind and polar stratospheric cloud (PSC) characteristics in the winters showed that the zonal average of minimum temperature (50-90o N) at 50 hPa for both years remained less than the PSC formation threshold for almost four months, which is unusual in the Arctic. Zonal winds examined at 10 hPa were strongly westerly (40-50 ms-1) for most part of the winters giving rise to a long-lasting and extremely strong polar vortex. The higher rate of chlorine activation, the increased denitrification and higher vortex descent explain the severe ozone loss in 2011 and 2020. Both winters experienced the maximum ozone loss in April. The vortex disintegrates by mid-April in 2011 and by late April in 2020. The study concludes that the ozone loss amount was slightly more severe in 2019/20 (above 2.5ppmv) than that in 2010/11 (about 2.0-2.3 ppmv). Extreme winters of this nature could be possible harbingers of polar climate change.

218 Polar Science & Cryosphere studies

Evaluation of Sea-Ice and Ocean forecasts for the Antarctic: An Inter-comparison between coupled model and stand-alone ocean model. ORAL OSICON2021/236 Saheed P P1,2, Ashis K Mitra1, Vimalesh Pant2, Ankur Gupta1, Imran Ali1 1National Centre for Medium Range Weather Forecasting, Ministry of Earth Sciences, Noida ; 2Centre for Atmospheric Sciences, Indian Institute of Technology Delhi, New Delhi

The global coupled model (CNCUM) and standalone ocean model (NEMO) are running operationally at the National Center for Medium Range Weather Forecast- ing (NCMRWF). The CNCUM consists of Nucleus European Modeling of Ocean (NEMO), UM (Uniﬁed Model) atmospheric model and Los Alamos sea ice model (CICE), coupled through OASIS coupler. The stand-alone ocean model consists of NEMO and the CICE models. In the coupled model, both the atmosphere and the ocean model are initialized using the operational NCMRWF Uniﬁed Model (∼17 km) and NEMO variational assimilation. In this study, we evaluated the sea ice forecast and its associated atmospheric and oceanic parameters over the Antarctic during the peak melting (January-March) and peak freezing (July-September) seasons. This study explains the growth and melting of sea-ice in the Antarctic and its prediction from day 1 to day 10 forecasts. The study also describes how ocean variables are being forecasted during the same period.

219 Polar Science & Cryosphere studies

Five years of IndARC mooring- science and technology ORAL OSICON2021/243 Divya David T.1, Subeesh M. P.1, Kesavakumar B.2, Archana Singh1, M. Ravichandran1, Arul. Muthiah2, R. Venkatesan2 1National Centre for Polar and Ocean Research, Misnistry of Earth Sciences, Goa; 2National Institute of Ocean Technology, Misnistry of Earth Sciences, Chennai

Warming, glacial melting, and sea-ice declining in the Arctic region have become layperson’s talk nowadays. Long-term monitoring of the Arctic Ocean processes has the utmost importance in understanding them and their worldwide impacts. In 2014, NCPOR, in collaboration with NIOT, deployed a subsurface mooring called ‘IndARC’ in Kongsfjorden, an Arctic fjord situated east of the Fram Strait through which warm- saline Atlantic water (AW) enters the Arctic Ocean. Kongsfjorden has a higher AW volume compared to other fjords south of it and larger glacier-induced freshwater discharge. These make it ideal for studying the changes due to the AW inflow and glacial melting. IndARC has physical, chemical, and biological sensors at discrete depths. Weak link at 25m, separating the mooring upper and lower parts, disconnects the upper part if struck by heavy ice, saving sensors below 25m. The signal from the beacon in the disconnected part helps identify and retrieve it. Two acoustic releases are connected in tandem capable of withstanding the mooring load suiting the Arctic conditions. In this discourse, we discuss the mean, seasonal, and inter-annual variability in temperature, salinity, current, photosynthetically active radiation, dissolved oxygen, chlorophyll a, and nitrate from summer 2014 to 2019. Winter water column temperature never attained freezing point during the observation. The temperature minimum was in February or March. The rate of increase in summer water temperature is 0.12◦C/yr. The upper fjord recorded the lowest salinity in October 2015 (33.6 psu) and 2017 (34 psu), corresponding with the highest recorded air temperature periods. The low surface salinities owe to the warming- induced increase in glacial discharge into the fjord. AW was detected every year continuously from early summer till December from its characteristic temperature- salinity and up-fjord currents below 60 m. This indicates an increased AW residence time compared to the earlier decades. However, the AW occupancy had discontinu- ities during other seasons. AW brings more nitrate into the fjord during non-bloom periods influencing nutrient dynamics. Apart from the inter-annual variability, we found a strong coupling between seasonal fjord physics and biogeochemistry. The five-year experience shows India’s capability to carry forward a robust Arctic ocean observation network.

220 Polar Science & Cryosphere studies

Signature of seasonal surface warm water core along the west coast of Svalbard, Arctic QUICK ORAL S. M. Pednekar OSICON2021/312 National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Goa

Climate change in the Arctic Circle is significantly felt in the recent decade due to the warming seas, in this perspective innumerable physical systems must have acted upon for the possible changes. The overall effects of these changes on the expanse of glaciers ice and snow inhabiting the surroundings have been of serious concern. In this study, we examine spatial variability of the surface warm-core of sea surface temperature concerning the sea ice concentration in the vicinity of Svalbard utilizing monthly NOAA optimal interpolated SST and sea ice concentration product of 38 years from January 1982 to December 2019. RMS has shown high variability region west of Svalbard. The monthly averages performed on 38 years of OISST have shown the warmest (coolest) surface water core along the west coast of Svalbard having temperature > 6.0oC(< 2.0oC) during August (February) when sea ice concentration is 0% (> 0%). Warming (cooling) begins in May (December), intensifies in August (February) and further diminishes in November (April). Off the west coast and south of Svalbard (Norwegian Sea) revealed higher (lower) temperatures than the surrounding other regions in summer (winter), however, the warming (cooling) trend is perfect over most of the region. The studies have confirmed significant spatial and temporal variation in the magnitude of winter and summer SST in different ranges. The seasonal extent of sea ice concentration controls the formation responsible for climate change in the Svalbard, Arctic region. The analyses will be done further to understand the physical processes involved.

221 Polar Science & Cryosphere studies

An updated trends of global sea ice condition in a warming world QUICK ORAL Kshitija S., Babula Jena, C. C. Bajish, N. Anilkumar OSICON2021/349 National Centre for Polar and Ocean Research, Ministry of Earth Science, Vasco-da-Gama, Goa

Polar regions have experienced a stunning change in sea ice condition with a background of warming world. The impact of global warming on the Arctic sea-ice showed a sharp declining trend as expected. In contrast, the Southern Ocean sea- ice extent showed an overall increasing trend of 0.43% per decade after considering the past 42 years of satellite record (1979-2020). Despite the moderate expansion of sea ice in Southern Ocean, a record decrease in sea-ice extent since spring 2016 have puzzled the scientiﬁc community. In this study, we describe the updated trends of global sea ice on monthly, seasonal, and annual timescales. Further, we explain the ocean-atmospheric processes that drives the observed variability in Southern Ocean sea-ice. Arctic ocean sea ice showed a steady declining trend with largest decline of 13% per decade in the eastern Arctic region. However, in the Southern Ocean, we observed the record highest sea ice extent in year 2014, followed by the decline in subsequent years, marking the annual lowest value in 2017 and monthly lowest in February 2017 and 2018. The sea ice changes in recent years (2016-2020) showed a contrasting regional variability with pronounced reduction compared to the previous records (1979-2015). Moreover, the sea-ice variability showed an alternating pattern of advancing and retreating trends associated with the Antarctic- wide atmospheric zonal wave patterns. The polar sea-ice is an important driver of global climate. The studies on interaction between ice-ocean-atmosphere system is necessary for better understanding of the global climate.

222 Mathematics in Ocean Science (MOS)

Session Chairman

Dr. C. Gnanaseelan Indian Institute of Tropical Meteorology (IITM), Pune, Maharashtra

223 Mathematics in Ocean Science

Evaluation of the best performing WaveWatch III model setup for the Indian Ocean ORAL OSICON2021/62 Abhijith Raj, B. Praveen Kumar, P. G. Remya, Meenakshi Sreejith Indian National Centre for Ocean Information Services, Hyderabad

Wave models use numerical schemes to represent the wave parameters, and their accuracy depends on the efficiency of the parameterization. The Indian Ocean (IO) experiences seasonal wind reversal, which makes it unique among other oceans. An ocean wave model for the IO based on WAVEWATCH III is used to evaluate the performance of the different parameterization schemes (known as ST2, ST3, ST4, and ST6) solely for the basin, addressing its uniqueness. The analysis of wind speed, especially in the north IO, shows weak winds in pre-monsoon, medium and strong winds during monsoon, and extreme winds during cyclones. The performance of the schemes is assessed in detail for different wind regimes (weak (<5 m/s), medium (5-10 m/s), and strong (>10 m/s)) using available measurements from buoy stations across north IO and satellite altimeters. This analysis using in-situ data from NIO buoy in different wind speed ranges shows that all the schemes have significant errors in the weak and strong wind speed ranges. Given the only forcing in the wave model is wind speed, an analysis of forecast winds showed that the forecast winds also have good performance in the medium range compared to weak and strong winds. The problems in the parameterization and errors in the forecast winds make the predictions challenging in low and extreme wind conditions. Further, the performance of different schemes is evaluated for different seasons in IO, cyclone case (cyclone Ockhi), and swell event cases during the period of study. Except for cyclonic conditions, ST4 is the best scheme for predicting IO waves throughout the year (Scatter index <0.2 and Correlation >0.8), Still it needs further tuning in the cyclone wind conditions to generate peak wave heights. ST6 scheme to be the best performing scheme for predicting the cyclone-generated high waves. The performance of the ST2 was good in the low and medium wind ranges, while ST3 failed to perform in all the different scenarios considered in the study. Comparison of drag coefficient (Cd) from the model and observations also shows the deviation of Cd is more in the low and high wind speed ranges, indicating the need for tuning of the schemes for the accurate prediction of low and high waves.

224 Mathematics in Ocean Science

Cubic spline polynomial as input energy spectrum for determining the nonlinear energy transfer rates in a wave spectrum ORAL OSICON2021/130 Vaishnavi S., Prabhakar V. Division of Mathematics, School of Advanced Sciences, VIT Chennai

Non-linear energy transfer between wind waves involved in a gravity wave spectrum play a key role in the evolution of waves and is represented in the energy balance equation of the wave model (such as WAM, WWIII, etc.), as a separate source term, called nonlinear source term. Existing methods for the nonlinear source term are either approximate methods (which do not account for the full set of quadruplets and are being improved for accuracy) or exact methods (which require computational efficiency and are considered as research models). The focus of this paper is to present nonlinear energy transfer results using Gauss-Legendre Quadrature Method (GLQM) with cubic spline fitted polynomial as input spectrum in place of the theoretical spectrum and validating the results with that of the theoretical spectrum. We considered both single and double peaked theoretical spectra as input spectrum. The nonlinear results are also presented to illustrate the reduction in the computational time of the method with cubic spline technique employing less points of the input spectrum without affecting the nonlinear results for the full set of points of the same input spectrum. Imposing cubic spline fitting technique does not disturb the accuracy of the GLQM and also paves a two folded way-out as follows: 1. To fit the set of data of the input spectrum (Single peaked, Multipeaked or measured). 2. To reduce the computational time of the method considered (GLQM) in the present paper.

225 Mathematics in Ocean Science

Sea Surface Temperature Projection for the Bay of Bengal under RCP8.5 using 1D PWP Model ORAL OSICON2021/221 Hitesh Gupta, and Sourav Sil School of Earth, Ocean and Climate Sciences, Indian Institute of Technology Bhubaneswar, Odisha

The Bay of Bengal is a relatively unique body of water, governed by reversible winds and advection of massive freshwater from nearby rivers as well as monsoonal precipitation. The low saline water overlying hypersaline water, generating strong stratification and limiting turbulent mixing make the BoB dynamics complex. The halocline that results inhibits wind-driven mixing of the topmost layers, altering or influencing the water body’s optical properties. In this study, data from the Research Moored Array for African-Asian-Australian Monsoon Analysis and Pre- diction (RAMA) Buoy, INCOIS TropFlux, and Tropical Rainfall Measuring Mission (TRMM) Rainfall have been taken to drive the 1-D Price-Weller-Pinkel (PWP) model for a year (2015- 16) at different locations along 90oE to explore how absorption length of incoming solar (shortwave) radiation varies with space and time. It was found that an average absorption length is around 40 m at location 90oE 15oN. Representative concentration pathway (RCP) 8.5 has also been carried out at this location and the generation of absorption length values. Two methods have been adopted to carry out RCP8.5 - (a) Increment in incoming shortwave to the ocean by 8.5 W/m2, (b) decrement in outgoing longwave radiation from the ocean by 8.5 W/m2. The RCP8.5 calculations show a 0.64oC and 1.14oC increase in mean and maximum surface temperatures (if shortwave insolation is enhanced by 8.5W/m2), and a 0.77oC and 1.42oC increase (if outgoing longwave radiation is lowered by 8.5W/m2). These alterations have the potential to influence monsoon and cyclone features, which are both scientifically and societally significant. The results of the study are encouraged to be used for mixed layer heat budget analysis, modelling, and other purposes.

226 Mathematics in Ocean Science

Applications of AI/ML in Fish Biomass Estimation System ORAL OSICON2021/235 Srinivas Bolem, Nitesh Verma, Arathy Nair, Muthukumaravel S, Dharani G, Tata Sudhakar National Institute of Ocean Technology, chennai

Increasing population has put a great demand on source of protein for its consumption. Marine resources offer rich natural source of protein. Today, fish cage farming is emerging as a feasible means for providing sustainable livelihood for a large number of populations. The demand of increasing food supply can be fulfilled by increasing the yield from the fish cages culture. Stipulated manpower and funds to be earmarked for maintenance and monitoring purposes. Traditionally, fish farm- ers have to kill random fishes in routine to determine their growth. On the other hand, Marine Biotechnologists record the underwater video and depend on post processing technique to do the same. Thus, there is strong demand to develop a system to reduce the human intervention.”Intelligent Real Time Fish Biomass estimation system (I-BIOMES)” is a field deployable unit to detect the fish, analyze the data for Biomass estimation. The system is deployed in the open sea fish cages. On runtime it will select the video grabs as frames to measure the fish length, process it and calculate the biomass. Principle of fish biomass estimation from underwater camera based system is a two step process. First step is to obtain the length of fish from underwater imaging. Object detection is a computer vision technique to find and locate an object in the given frame from images or videos. By leveraging on Machine Learning, the system can detect multiple objects in a single frame more efficiently. Considering the Fish as an object, the system can be trained on the customised model and use for fish detection in different environments and obtain length measurements. The second step is the calculation of weight from the length estimated using the Length Weight Regression Model specific to the species of fish cultured. The allometric equation is evaluated separately for each species using extensive data of length and corresponding weight of fish species. The result of the two steps is shown in Figure 1. Initially the system is validated by testing with known fish samples. Further performance is evaluated by ICAR-CIBA tank cultured fishes. The I-BIOMES system is deployed in open floating type fish cage at Andaman in March, 2020 and initial performance is discussed. The real time results are acceptable and adequate enough for more developmental works. The accuracy for length measurement using this system as compared to manual measurement, and is 95% accurate. It can be improvised and scaled to other species.

227 Mathematics in Ocean Science

Assessment of CMIP6 models’ skill for tropical Indian Ocean sea surface temperature variability ORAL OSICON2021/258 Subrota Halder1,2, Anant Parekh1, Jasti S. Chowdary1, C. Gnanaseelan1, Ashwini Kulkarni1 1Indian Institute of Tropical Meteorology, Ministry of Earth Sciences, Pune; 2Savitribai Phule Pune University, Pune

The present study examines the ability of Coupled Model Inter-comparison Project phase 6 (CMIP6) models in representing the dominant modes of tropical Indian Ocean (TIO) sea surface temperature (SST) variability on the interannual and decadal time scale. Historical simulations from 27 CMIP6 models are assessed against Extended Reconstructed SST from 1854 to 2014. Spectrum analysis reveals that many models reproduce interannual and decadal variability of TIO SST but underestimate the amplitude of variability with some disparity in the periodicity. All models can reproduce the dominant basin-wide mode of interannual and decadal variability of TIO SST reasonably well. Skill score analysis of TIO SST variability reveals that KACE-1-0-G has the highest skill, followed by FGOALS- f3-L, EC-Earth3-Veg-LR, ACCESS-ESM1-5, CanESM5-CanOE on the interannual timescale, and FGOALS-f3-L, CanESM5-CanOE, KACE-1-0-G, and CanESM5, respectively, showed the highest skills for decadal variability. It is found that variations in radiation and latent heat flux are primarily responsible for interannual variability in TIO SST, the basin-wide warming, in the observations. Taylor diagram analysis reveals that all the models exhibit better skill for the radiative flux; however, skill for the latent heat and momentum flux varies from model to model. It is important to note that the models in which the latent heat flux and zonal wind are better represented have produced better TIO SST variability compared to other models. A higher discrepancy in latent heat and zonal momentum flux leads to improper wind-evaporation-SST and wind-circulation-SST feedback, which in turn restricts the model skill. Besides, model that has realistic central and eastern Pacific SST variability show better skill for TIO SST variability in both interannual and decadal time scales. The present study advocates that a better representation of latent heat flux and zonal wind in coupled models is important for the accurate simulation of interannual and decadal variability in TIO SST.

228 Mathematics in Ocean Science

A study of mixing and biological activity in the Arabian sea using Finite Size Lyapunov exponents ORAL OSICON2021/322 Jai Kumar1, Ravi Kamal Choudhary1, Manikandan Mathur2, Neeraj Agarwal1, and Rashmi Sharma1 1 Space Applications Centre, ISRO, Ahmedabad 2 Department of Aerospace Engineering, Indian Institute of Technology, Chennai

In this work, we present a study of the horizontal mixing properties in the North Indian Ocean using Finite Size Lyapunov Exponents analysis (FSLE) generated using satellite derived and numerical ocean model simulated surface velocity fields. The period of analysis in this study is from 2016–2020. Based on mixing activities inferred from the annual mean of backward and forward FSLE (bFSLE and fFSLE) fields, few sub-domains are selected in the Western and south eastern Arabian sea and in the Bay of Bengal. An investigation of links between satellite derived chlorophyll concentration and biological activity is done in the selected sub-regions and it is found that surface horizontal stirring and mixing vary inversely with chlorophyll standing stocks. Further, seasonal and inter-annual variations of bFSLEs field are analysed to study the mixing characteristics of ocean on these time-scales. The detailed results will be presented in the conference.

229 Mathematics in Ocean Science

Using Machine Learning to Characterize Ocean Basins ORAL OSICON2021/348 Sapkal Mayur1,2, Singh Shikha1 1 Indian Institute of Tropical Meteorology (IITM), Pune; 2 Department of Atmospheric and Space Sciences, Savitribai Phule Pune University, Pune

The Indian Ocean is a closed ocean. It has complex spatial variability, characterized by the formation of high salinity water in the Arabian Sea and even more extreme in the Red Sea and the Gulf. In the north, there is a significant variation in precipitation between the eastern and western areas. Because of its geographic location, climatic conditions, isolation from other oceans, and its present pattern, the water masses of the Indian Ocean vary from those of other oceans. Traditionally, determining Indian Ocean spatial structures has relied on ad hoc combinations of physical, chemical, and dynamic properties. We apply an unsupervised classification technique (Gaussian Mixture Modelling, also known as GMM) to Indian Ocean (IO) Argo float temperature and salinity profiles as a step toward an alternative method for defining spatial variations in temperature and salinity structure between 0 dbar and 1000 dbar pressure level. GMM automatically distinguishes many spatially coherent groups influence by temperature and low/high salinity water masses without using any latitude or longitude detail. In addition, GMM detects outliers among the various Argo Floats. GMM can theoretically be used to classify constructs in both observational and model data sets because it is stable, systematic, and automatic, making it a valuable supplement to existing classification techniques. This is noteworthy because the climate science and ocean sciences communities need a new generation of methods, perhaps including the machine learning techniques described in this report, to deal with a vast and growing amount of observational and computer model data.

230

INAUGURATION (Bharati Hall) 09:30 - 11:30 PLENARY TALK BY HON. FELLOW

11:30 - 11:45 Tea Break

PARALLEL SESSION 1 (Bharati Hall) Technical Session 1: Marine Ecosystems and Biogeochemistry of the Ocean (MEBO) Session Chairman: Prof. K.V. Jayachandran, KSBB, Coordinators: Dr. Siby Kurian, Dr Sabu P. Invited Talk: 11:45 - 12:15 Dr. GVM Gupta, CMLRE, Kochi “Are Indian coastal seas really polluted? – Myths and Effects” Time Speaker Reg. No Title of Presentation Gopala Krishna Understanding the distribution of plastics in lower Ganga basin and their fate in river & marine 59 12:15 - 12:30 Darbha waters Sarat Chandra Biophysical Control on Variability in Phytoplankton Production and Composition in the South- 77 12:30 - 12:45 Tripathy Western Tropical Indian Ocean during Monsoon

Pandi Sudarsana Interannual and spatial variability of bio-optical characteristics in the Indian sector of Southern 83 Rao Ocean during austral summer 12:45 - 13:00 13:00 - 14:00 Lunch Break

Technical Session 4: Marine Ecosystems and Biogeochemistry of the Ocean (MEBO)

DAY 1 Session Chairman: Dr. C. Revichandran, NIO Coordinators: Dr. Anand. P, NPOL & Sh. Vikash Kumar, NCPOR Time Speaker Reg. No Title of Presentation

14:00 - 14:15 E.V. Ramasamy 232 Abundance and Distribution of Microplastics in the Water Column of Southern Ocean

Vankara 14:15 - 14:30 89 Inter-annual variability of zooplankton assemblages in the Indian sector of the Southern Ocean Venkataramana 12 August 2021 (Thursday) :

Factors controlling the Inter-annual variability of Particulate Organic Matter Characteristics in the 14:30 - 14:45 Melena A. Soares 103 Indian Sector of the Southern Ocean Impact of Siderophore producing bacteria, iron, and dissolved siderophore on coccolithophore 14:45 - 15:00 P V Bhaskar 124 and diatom monocultures 15:00 - 15:15 Samir Damare 179 Emergence of omics as a tool to study life in the Oceans 15:15 - 15:30 S V Sandhya 296 Algicidal bacteria as a promising candidate for control of harmful algal blooms Aseem Ranjan Phytoplankton community structure in relation to the environmental conditions from the tropical 15:30 - 15:45 215 Rath Kandla port ecosystem

15:45 - 16:00 Lata Gawade 87 Microbial carbon pump: Reservoir for ocean carbon- future prospects for carbon sequestration

16:00 - 16:15 Tea Break

The impacts of physical forcing on POM, δ13 CP OC and δ 15 NP N variability in the central 16:15 - 16:30 Saumya Silori 195 Arabian Sea during SW monsoon (2017-2018)

Vasudha C. 16:30 - 16:45 196 Potential of marine bacteria for biodegradation of polycyclic aromatic hydrocarbon Bhatawadekar Development of a bioenergetics model for Indian oil sardine (Sardinella longiceps) and 16:45 - 17:00 Faseela Hamza 224 simulation of its seasonal growth along the Indian west coast

Session End

INAUGURATION (Bharati Hall) 09:30 - 11:30 PLENARY TALK BY HON. FELLOW

11:30 - 11:45 Tea Break

PARALLEL SESSION 2 (Maitri Hall) Technical Session 2: Coastal and Open Ocean processes (COOP) Session Chairman: Dr. Sanil Kumar VV, NIO Coordinators: Dr. Anilkumar V, CMLRE & Dr. Prince Prakash, NCPOR Invited Talk: 11:45 - 12:15 Dr. Srinivasa Kumar, INCOIS, Hyderabad “Ocean Observations, information and Advisory services” Time Speaker Reg. No Title of Presentation

o 12:15 - 12:30 Imranali M Momin 169 Simulation with Eddy Resolving High Resolution (1/12 ) Global NEMO Ocean Model Role of sea surface temperature anomalies of Arabian sea in extreme weather events at Dr Niket Shastri 60 12:30 - 12:45 Western Coast of Indian Subcontinent

Vineet Kumar 244 Role of ocean-atmosphere in the recent changes in cyclone activity in the North Indian Ocean Singh 12:45 - 13:00

13:00 - 14:00 Lunch Break Technical Session 5: Coastal and Open Ocean processes (COOP) DAY 1 Session Chairman: Prof. A. D. Rao, IITD Coordinators: Dr. Mani Murali, NIO & Dr. Parijat Roy, NCPOR Time Speaker Reg. No Title of Presentation

Sidha Sankalpa 14:00 - 14:15 155 Atlantic hurricanes of 2020 and the factors influencing them Moharana

Kuvar Satya Singh Climatological characteristics of atmospheric parameters during the rapid intensification of 14:15 - 14:30 328 / Thatiparthi K. tropical cyclones over the North Indian Ocean 12 August 2021 (Thursday) :

Dr. Basanta 14:30 - 14:45 3 Decadal shoreline morphological changes using satellite images of goa coast Kumar Jena Saranya 14:45 - 15:00 184 Dynamics of mercury in a monsoon fed tropical estuarine system during dry season Jayachandran Characteristics of Diurnal Sea Surface Temperature Variability in the North Indian Ocean and 15:00 - 15:15 Martin M. V. 351 its Implications to Air-Sea fluxes 15:15 - 15:30 Anoopa Prasad C 247 Intense upwelling in the southeastern Arabian Sea during the post-monsoon season Observed inter-annual variability of temperature inversions over northern 15:30 - 15:45 Antony P Thomas 227 Bay of Bengal: the role of Indian Ocean Dipole

15:45 - 16:00 Swaleha Inamdar 198 Understanding iodine emissions in the Indian and Southern Ocean marine boundary layer

16:00 - 16:15 Tea Break

ROMS simulations of physical and biogeochemical parameters for ‘NARGIS’ cyclone in the 16:15 - 16:30 Tarumay Ghoshal 178 Bay of Bengal Sanjaya Kumar 16:30 - 16:45 98 Geographical Mapping System (GMS): An improved GIS in Disaster Management. Sarangi Akhilesh Kumar Implementation of NEMO based high resolution regional coupled model at the National Center 16:45 - 17:00 220 Mishra for Medium Range weather Forecasting (NCMRWF)

Session End

INAUGURATION (Bharati Hall) 09:30 - 11:30 PLENARY TALK BY HON. FELLOW

11:30 - 11:45 Tea Break

PARALLEL SESSION 3 (Himadri Hall) Technical Session 3: Climate Change (CC) Session Chairman: Dr. D. Bala Subrahamanyam, SPL Coordinators: Dr. Anoop S. Mahajan, IITM & Dr. Nuncio M, NCPOR Invited Talk: 11:45 - 12:15 Dr. Raghu Murtugudde, University of Maryland, USA "Climate change and the seas around us: India and the Ocean" Time Speaker Reg. No Title of Presentation Ramesh Kumar Relationship between Azores High and Indian summer 58 12:15 - 12:30 Yadav monsoon Dr.Surendra 24 Studies on tropical zooplankton and climate change, west coast of India

12:30 - 12:45 S.Kadam The decadal sea level variability observed in the Indian Ocean tide gauge records and its

DAY 1 12:45 - 13:00 Deepa J S 159 association with global climate modes

13:00 - 14:00 Lunch Break Technical Session 6: Climate Change (CC) Session Chairman: Dr. Supriyo Chakraborty, IITM Coordinators: Dr. Kripa Ram, BHU & Dr. Parmanand Sharma, NCPOR Time Speaker Reg. No Title of Presentation

Darshana D. CMIP5 and CMIP6 fidelity in representing the IPOC mode characteristics and its link with the

12 August 2021 (Thursday) : 14:00 - 14:15 262 Patekar Indian summer monsoon rainfall

QUICK PRESENTATION (5 minutes)

Sanjukta Rani Frequency of monsoon depression over the Indian seas and landmass during onset, withdrawal, 14:15 - 14:20 180 Padhi and main monsoon season and the associated rainfall variability Denitrification record from Eastern Arabian Sea indicating South Asian Monsoon Variability 14:20 - 14:25 Padmasini Behera 97 during late Pliocene 14:25 - 14:30 Parvathy Anil 250 Long-Term Changes In Monsoon Winds In Response To Ocean Warming 14:30 - 14:35 Barnali Das 119 Bi-decadal variation of saltwater vulnerability in coastal district of Raigad, Maharashtra, India. Ocean warming over the past three decades: Implications on Arctic methane emissions caused 14:35 - 14:40 Akash Trivedi 84 by hydrate dissociation Primary Productivity and Bio-optical Variability in the Indian Sector of the Southern Ocean: 14:40 - 14:45 Anvita Kerkar 164 Observations from Austral Summer 2015

14:45 - 14:50 Sritama Baag 78 The physiological response of Scylla serrata under the influence of climate change related factors and oil pollution

14:50 - 14:55 Apurva P Joshi 82 Modeling the drivers of the spatiotemporal variability of the surface pCO2 in the Bay of Bengal 14:55 - 15:00 Jiya Albert 21 Response of Ocean Heat Content variability on Cyclone Frequency over North Indian Ocean

Session Contd….

Time Speaker Reg. No Title of Presentation T.German Amali Assessment of climate variability in coastal wetlands of pichavaram mangroves through satellite 15:00 - 15:05 292 Jacintha images Combined Influence of ENSO and IOD on the strength of Northeast Monsoon Rainfall over the 15:05 - 15:10 E.K. Simon 226 peninsular India Performance of COWCLIP Significant Wave Height datasets and Extreme Wave Height 15:10 - 15:15 Athira Krishnan 20 Projections for the Indian Ocean

Meenakshi 15:15 - 15:20 61 Footprints of Southern Annular Mode on The Indian Ocean Waves Sreejith

DAY 1 15:20 - 15:25 Nishtha Agrawal 101 Regional Modeling of Extreme Temperature Trends over India Demonstrating the potential of Regional Ocean Model System (ROMS) in simulating the upper 15:25 - 15:30 Prabha Kushwaha 231 ocean characteristics over Arabian Sea: impact of horizontal resolution West Pacific subtropical high, typhoon activity over northwest Pacific and linkage with Indian 15:30 - 15:35 Roja Chaluvadi 233 summer monsoon rainfall 15:35 - 15:40 Anusree A 15 Future Projection Of Indian Ocean Temperatures Under Global Warming Genesis and trends in marine heatwaves over the tropical Indian Ocean and their interaction 15:40 - 15:45 Saranya J S 51 with the Indian summer monsoon 15:45 - 15:50 Parvathy M 306 Analysis of the intensity and expansion rates of tropical expansion

12 August 2021 (Thursday) : Relationship between Global SST and Summer Monsoon Rainfall in Six Intensity Bins over Five 15:50 - 15:55 Reshma T 316 Homogenous Regions in India Intraseasonal oscillation of boreal monsoon rainfall and its coherence with meridional sea 15:55 - 16:00 Reji Mariya Joy 305 surface temperature gradient in the Bay of Bengal Benefits of satellite XCO2 and newly proposed atmospheric CO2 observation network over India 16:00 - 16:05 Santanu Halder 284 in constraining Indian Ocean prior fluxes 16:05 - 16:10 Arjun 160 India’s Mission of a 'Clean and Green Navy’ Session End

PARALLEL SESSION 1 (Bharati Hall) Technical Session 7: Marine Ecosystems and Biogeochemistry of the Ocean (MEBO) Session Chairman: Dr T. Balasurbramaniam, CARE Coordinators: Dr. Samir Damare, NIO & Dr. Waliur Rahaman, NCPOR Invited Talk: 09:30 - 10:00 Prof. Sunil Kumar Singh, NIO, Goa "The importance of Geotracers Program and way forward" Time Speaker Reg. No Title of Presentation S. Environmental Interaction of water quality, phytoplankton and zooplankton in pelagic food web of 10:00 - 10:15 245 Sundaramoorthy Ghogha coastal waters in Gujarat 10:15 - 10:30 Aditi Modi 249 Biophysical interactions over the tropical Indian ocean in a changing climate A simple technique to mitigate microplastic pollution and its mobility (via ballast water) in the 10:30 - 10:45 Ravidas K Naik 256 global ocean Two new carnivorous sponge (porifera, cladorhizidae) species from the central Indian ridge 10:45 - 11:00 Baban S Ingole 357 seamounts The observed variability of dissolved oxygen, chlorophyll and CDOM along the south eastern 11:00 - 11:15 Deepulal P M 299 Arabian sea waters 11:15 - 11:30 Tea Break QUICK PRESENTATION (5 minutes) Variability in diatom frustule and dinoflagellate cyst in the short sediment cores from two 11:30 - 11:35 Medhavi Pandey 260 locations in the eastern Arabian Sea

Determination of Bioaccumulation in marine ecosystem by Laser Induced Breakdown 11:35 - 11:40 Della Thomas 350 Spectroscopy DAY 2 Roy Valentino Salinity changes may influence dinoflagellate cyst morphometry: data from monsoon influenced 11:40 - 11:45 190 Rodrigues tropical coastal ecosystems. Analysis of microplastics in water samples collected from five sewage treatment plants of 11:45 - 11:50 Runkob Srimani 35 Kolkata. Nithya 11:50 - 11:55 36 Estimation and identification of microplastics & heavy metals ingested by fishes in Kerala Thulasidharan Gowthamy 11:55 - 12:00 37 Estimation and identification of heavy metals in sewage water Satheesan 13 August 2021 (Friday) : (Friday) 2021 13 August 12:00 - 12:05 Sreevidhya R 43 The Role of Organic Nutrients on The Sustainability of Primary Production in The Bay of Bengal

12:05 - 12:10 Gopikrishnan G S 46 Assessment Of Formaldehyde Over the Indian Ocean and Its Impact on the marine environment Microplastics in Marine and Freshwater System: A Review on Micro plastics and Heavy Metals 12:10 - 12:15 Emil John C R 63 Accumulation on Fishes Biswarup Assessment of seasonal cycle of physical and biological variables from CMIP6 ocean 12:15 - 12:20 64 Bhattacharya biogeochemistry models over the tropical Indian Ocean Analysis of Water Quality of Samples Collected from Ernakulam, Alappuzha and Kottayam 12:20 - 12:25 Darsana K K 67 Regions, Kerala, India 12:25 - 12:30 Debasish Ratha 115 Evaluate the Impact of marine pollution in the tourist beach Gopalpur, Bay of Bengal Spatial and seasonal trends of trace metals in the surficial sediments from off Kochi - 12:30 - 12:35 Princy M John 123 geochemistry and environmental implications Anil Kumar 12:35 - 12:40 132 Impact of heavy load nutrient on Seagrass growth in tropical environment: a review article Behera 12:40 - 12:45 Lamjahao Sitlhou 163 Kinetic speciation of Cu,Ni,Co in Deep Sea sediment from the Central Indian Ocean Basin Marker pigment-based phytoplankton community structure in relation to wind forcing in the 12:45 - 12:50 Mintu Chowdhury 193 central Arabian Sea: SW monsoon (2017-2018) Simulated ocean acidification and Cu enrichment promote pennate diatom dominance in the 12:50 - 12:55 Diksha Sharma 194 central Arabian Sea 12:55 - 13:00 Swastika Bhaumik 219 Impact of Covid-19 lockdown on the base of marine food web in the North Indian Ocean

13:00 - 14:00 Lunch Break

PARALLEL SESSION 1 (Bharati Hall) Technical Session 10: Marine Ecosystems and Biogeochemistry of the Ocean (MEBO) Session Chairman: Prof. Parthasarathi Chakraborty, IIT-KGP Coordinators: Dr. Damodar Shenoy, NIO & Dr. Bhaskar PV, NCPOR Invited Talk: 14:00 - 14:30 Dr. Vinu Valsala, IITM, Pune "Importance of Biogeochemistry of Indian Ocean and way forward" Time Speaker Reg. No Title of Presentation

14:30 - 14:45 D Sathish Kumar 340 Application of CROCO+NPZD model to simulate the coastal biochemical variability Accumulation of Petroleum Hydrocarbons in Zooplankton at Nagapattinam coastal water, Bay of 14:45 - 15:00 S. Sundararajan 317 Bengal, South East coast of India. Mukunda Kesari Evaluation of the heavy metal pollution in the estuarine ecosystem of Tapi and its sustainable 15:00 - 15:15 342 Khadanga management, Arabian Sea. 15:15 - 15:30 Anju Mallissery 346 Development of a coupled physical biogeochemical model for the Indian Ocean 15:30 - 15:45 Tea Break

QUICK PRESENTATION (5 minutes) Characterization of extracellular enzyme activities of bacteria from the water and sediment sand 15:45 - 15:50 Ashutosh Parab 144 along the west coast of India during monsoon season

15:50 - 15:55 Shruti Shah 207 Effect of nutrient enrichment under pressure on the microbial diversity- A metagenomic approach

DAY 2 Diptangshu 15:55 - 16:00 225 Iron Biogeochemistry in the Southern Ocean Sarkar Morphological and taxonomic diversity of micro-phytoplankton from the south-eastern Arabian Sea 16:00 - 16:05 Pranoy Paul 162 during 2020 winter monsoon: elucidation from surface and sub-surface chlorophyll maximum layers The first report of seasonal distribution of phytoplankton functional type (PFT) & phytoplankton size 16:05 - 16:10 Sambit Singh 230 classes (PSC) in Chilika, the largest coastal lagoon in India Balamurugan 16:10 - 16:15 257 Application of machine learning to predict the copepod-bacterial association Sadaiappan Spatiotemporal distribution of diatom community with distinct salinity regimes along the Kali estuary, 16:15 - 16:20 Akshata Naik 336

13 August 2021 (Friday) : Karwar, West Coast of India Rajeshree Ingression and seasonal abundance of Decapoda Larvae along the Kali estuary, Karwar, West 16:20 - 16:25 337 Pednekar Coast of India The Preliminary study of coastal water acidification monitoring in the Palk Bay, Southeast coast of 16:25 - 16:30 B Kamalakannan 341 India. Frontal Variability of Phytoplankton In The Indian Sector Of Southern Ocean During Austral Summer 16:30 - 16:35 Sreerag A 168 2018 Soubhik 16:35 - 16:40 175 Seasonal variation of POC in Bay of Bengal using Satellite Data Bhattacharya Shreya Suresh 16:40 - 16:45 253 Marine Algae: A Great Human Food Source Moraskar 16:45 - 16:50 Meenakshi 288 sea foam: a unique habitat in the marine ecosystem The first report on spatio-temporal distribution of Chromophoric Dissolved Organic Matter (CDOM) in 16:50 - 16:55 Susmita Raulo 298 Chilika, the largest coastal lagoon in India Harsha 16:55 - 17:00 Dnyaneshwar 307 Biotechnological potential of diatoms Gaonkar Blossom Carol 17:00 - 17:05 308 Distribution of Microplastics in coastal regions of India Dias Mrinalini Chandra 17:05 - 17:10 309 Oil spills in the marine environment and associated microbiology Mohan Monitoring of farmed shrimps (Penaeus vannamei) from Nagapattinam region of Tamil Nadu, India 17:10 - 17:15 Akalesh 45 for Salmonella contamination 17:15 - 17:20 Sunanda N 41 Did COVID-19 impact the Net Primary Productivity in the Arabian Sea? Session End

PARALLEL SESSION 2 (Maitri Hall) Technical Session 8: Coastal and Open Ocean processes (COOP) Session Chairman: Dr. M Baba, Former Director, CESS Coordinators: Dr. L Sheela Nair, NCESS & Dr. Melena A Soares, NCPOR Invited Talk: 09:30 - 10:00 Prof. B.N. Goswami, Cotton University, Guwahati "Local Ocean-atmosphere Interactions associated with the Indian Monsoon Multi-decadal Mode"

Time Speaker Reg. No Title of Presentation

10:00 - 10:15 Rohit Srivastava 113 Black Carbon characteristics over Indian ocean sector of the Southern Ocean Oxidised volatile organic compounds in the Indian Ocean and Southern Ocean marine boundary 10:15 - 10:30 Anoop Mahajan 22 layer 10:30 - 10:45 Shikha Singh 352 On the Variability of Arabian Sea Mixing and its Energetics Wind-Wave Relationship Considering Local and Remote Wave Effects from Moored Buoy 10:45 - 11:00 Dr. M. Kalyani 334 Measurements in the South-East Arabian Sea Damu Bala The Known and Unknown mysteries of Marine Atmospheric Boundary Layer under the influence of 11:00 - 11:15 177 Subrahamanyam a Tropical Cyclone: A Case Study during OCKHI Storm Dominic Ricky 11:15 - 11:30 339 Thermohaline and acoustic characteristics of the Sri Lanka Dome during July 2019 Fernandez Shrivardhan Third Revision of the Bottom-up Global Surface Seawater Dimethyl Sulfide Climatology (DMS- 11:30 - 11:45 199 Hulswar Rev3) 11:45 - 12:00 Tea Break DAY 2

QUICK PRESENTATION (5 minutes) Spatio-temporal Variability of Bio-optical Properties and Radiant Heating Rate in the Eastern 12:00 - 12:05 Partha Patil 167 Arabian Sea Study of large-scale Atmospheric convection over the tropical Indian Ocean and its association 12:05 - 12:10 Supriya 223 with Oceanic variables. Mr. Samar Anomalous variation of sea surface temperature and air temperature in coastal North Indian 12:10 - 12:15 246 Kumar Ghose Ocean in 2020: examining the role of Covid-19 lockdowns 13 August 2021 (Friday) : (Friday) 2021 August 13 Midhun shah 12:15 - 12:20 297 Warming driven early blooming scenarios in North Eastern Arabian Sea Hussain Performance of Atmospheric-Ocean Coupled Model in the prediction of Rapid intensification of 12:20 - 12:25 Reshma M. S. 329 Super Cyclonic Storm Amphan over the North Indian Ocean

12:25 - 12:30 Ardra D 44 The spatial and temporal variability of OH minimum over Indian ocean

12:30 - 12:35 Vinay Kumar 80 Validation of CMIP6 with the observations of SST in the Bay of Bengal

Shaikh Atiba Aerosol Distribution Over The Tropical Indian Ocean And The Role Of Atmospheric 12:35 - 12:40 90 Anis Ahmead Thermodynamics. To study the influence of Indian Ocean Dipole on Southern Hemisphere circulation during austral 12:40 - 12:45 Shrutee Jalan 131 spring Sankar Prasad 12:45 - 12:50 183 Inflow and spreading of the Red Sea and Persian Gulf water into the western Arabian Sea Lahiri Seasonal and Intraseasonal Variability of Winds and Associated Air-Sea Interaction in the Bay of 12:50 - 12:55 Sumana Mandal 185 Bengal from a Moored Buoy Observation Influence of sea breeze-land breeze circulation on thermodynamic parameters over Kochi, a 12:55 - 13:00 Linsha C. L. 291 coastal tropical station

13:00 - 14:00 Lunch Break

PARALLEL SESSION 3 (Maitri Hall) Technical Session 11: Coastal and Open Ocean processes (COOP) Session Chairman: Dr. S. Satheesh Shenoi, Former Director, INCOIS Coordinators: Dr. Rajdeep Roy, NRSC & Dr. V Venkataramana, NCPOR Invited Talk: 14:00 - 14:30 Dr. N Ramaiah, Former Chief Scientist, NIO, Goa “Sustainable Indian seas through enhanced biological research” Time Speaker Reg. No Title of Presentation

An improved nearshore bathymetric data from synergistic application of active and passive satellite 14:30 - 14:45 Surisetty V V 237 remote sensing and machine learning Uma Sankar Mixing zone analysis of brine wastewater disposal from desalination plant at Kadmat, Lakshadweep

DAY 2 14:45 - 15:00 213 Panda Islands Shyamala A study on the seasonal variation of nearshore waves along remote islands of UT Lakshadweep, 15:00 - 15:15 Varthini 285 West Coast of India Dinakaran Impact of assimilating satellite derived sea surface salinity from smos, aquarius and smap in a high 15:15- 15:30 Smitha Ratheesh 217 resolution ocean circulation model for the tropical Indian ocean: an observing system experiment framework

15:30 - 15:45 Tea Break 13 August 2021 (Friday) : (Friday) 2021 13 August Muhammad 15:45 - 16:00 313 Influence of low Saline Pool on the Upper Layer Dynamics of the South Eastern Arabian Sea Shafeeque Temperature Sensor Location Optimization Of Expendable Bathy Thermograph Using Numerical 16:00 - 16:15 Sona M. A. 153 Method Impact of COVID-19 associated lockdowns on the year-to-year variability of oil pollution along the 16:15 - 16:30 V Trinadha Rao 200 Eastern Arabian Sea Susant Kumar 16:30 - 16:45 201 Numerical interaction on tide, wind, wave & current off Gulf of Khambhat Misra Inter comparison of underwater acoustic properties derived from different reanalysed products and in 16:45 - 17:00 P A Maheswaran 338 situ observations in the South Eastern Arabian Sea Session End

PARALLEL SESSION 3 (Himadri Hall) Technical Session 9: Ocean Engineering and Technology (OET) Session Chairman: Dr. MA Atmanand, IIT-M Coordinators: Sh. PK Maurya, NIO & Dr. A Mukherjee, NCPOR Invited Talk: 09:30 - 10:00 Dr. M.V. Ramana Murthy, NCCR, Chennai “Recent trends in Coastal Research and Sustainable Coastal Technologies” Time Speaker Reg. No Title of Presentation

10:00 - 10:15 V Gowthaman 327 Performance of C profiler during the sea trail Alluri Satya Numerical study of wave transmission and interaction with submerged artificial reef at Puducherry

10:15 - 10:30 332 Kiran Raju Coast 10:30 - 10:45 D Nandhini 295 Seasonal sediment characteristics analysis of Kandla Creek and Gulf of Kutch DAY 2 Reshma George Physical model studies on damage and stability analysis of breakwaters with double layer GSC 10:45 - 11:00 65 V armour units Teppala Real-time estuary observatory system for monitoring Bhavanapadu estuary by utilizing the internet of 11:00 - 11:15 66 Vikranth underwater things 11:15 - 11:30 Akhil Varghese 86 Variability and accuracy in the estimation of sound speed in Indian waters Ponugmati Vijay Experimental studies on coastal dyke made of geotextile sand containers with coarse aggregate as 11:30 - 11:45 93 Charles bedding , core & secondary layers

13 August 2021 (Friday) : (Friday) 2021 August 13 11:45 - 12:00 Tea Break QUICK PRESENTATION (5 minutes) Victor Sustainable production of marine pre-biotic (Polysaccharides and oligosaccharides) using microbial 12:00 - 12:05 Ndilipunye 188 enzymes- future prospects Haimbala Importance of Tide Gauge Observations to Identify the Multi-scale Sea Level Variability over 12:05 - 12:10 Arkaprava Ray 228 Western Bay of Bengal 12:10 - 12:15 Merin C A 331 Effect of internal tides on acoustic propagation in the Central Arabian Sea

12:15 - 12:20 Arya Thomas 13 Optimisation of Floating Offshore Platforms for Wind Energy in Indian Coast 12:20 - 12:25 B. Yadidya 128 Internal tide energetics in the Andaman Sea 13:00 - 14:00 Lunch Break Technical Session 12: Ocean Engineering and Technology (OET) Session Chairman: Dr. NP Kurian, Former Director, NCESS Coordinators: Dr. Suprit Kumar, INCOIS & Dr. Sarat Tripathy, NCPOR Invited Talk: 14:00 - 14:30 Dr. Joseph Mathew, Sanctuary Beach Pvt. Ltd., Singapore.

“Coastal processes and coastal protection challenges"

DAY 2 Time Speaker Reg. No Title of Presentation Sunil Kumar 14:30 - 14:45 108 Soundscape in Summer in Kongsfjorden, Arctic Mohanta R. 14:45 - 15:00 138 Wave spectral characteristics of Two concurrent Cyclones Kyarr and Maha in the Arabian Sea Keerthivasan Reddy 15:00 - 15:15 187 Wave spectral characteristics in shallow waters off Goa coast during pre and post monsoon seasons Janakiram Santosh kumar Impact of future climate scenarios on Chloride ingress and Carbonation levels in coastal reinforced 15:15 - 15:30 212 B concrete structures 13 August 2021 (Friday) : 15:30 - 15:45 R.Janani 214 Study of wave spectral characteristics in deep water region in the southern Bay of Bengal Elizabeth shani 15:45 - 16:00 251 A statistical study of seasonal underwater noise as a function of wind and marine traffic N. X Shweta 16:00 - 16:15 95 Comparison of Vector Sensor Array Processing algorithms for Underwater Source Localization Lokhande Session End

PARALLEL SESSION 1 (Bharati Hall) Technical Session 13: Polar Science and Cryosphere studies (PSC) Session Chairman: Dr. M. Sudhakar, Former Director, CMLRE Coordinators: Dr Vimlesh Pant, IITD & Dr. Babula Jena, NCPOR Invited Talk: 09:30 - 10:00 Dr. N. Anilkumar, NCPOR, Goa "Decadal Indian Observational Campaigns in the Southern Ocean and the Future perspectives" Time Speaker Reg. No Title of Presentation Sincere Feeding and Utmost care to Brutal Cannibalism of Self Brood in South Polar Skua in 10:00 - 10:15 Prof. Shivaji P. Chavan 55 Schirmacher Oasis, Antarctica 10:15 - 10:30 Jenson V. George 85 Upper-ocean mixing during austral summer in the Prydz Bay region of East Antarctica Mixotrophic plankton population and Synechococcus distribution in waters around Svalbard, 10:30 - 10:45 Jane T Bhaskar 125 Norway during June, 2019. Evaluation of Sea-Ice and Ocean forecasts for the Antarctic: An Inter-comparison between DAY 3 10:45 - 11:00 Saheed 236 coupled model and stand-alone ocean model 11:00 - 11:15 Divya David T 243 Five years of IndARC mooring science and technology Inter-annual Variability Of Sea Surface Temperature in the Indian Sector Of Southern Ocean 11:15 - 11:30 Antony P Thomas 166 during the Austral Summer 11:30 - 11:45 Tea Break

QUICK PRESENTATION (5 minutes)

14 August 2021 (Saturday) : 11:45 - 11:50 Shailesh Pednekar 312 Signature of seasonal surface warm water core along the west coast of Svalbard, Arctic

11:50 - 11:55 Suraj Ravindran 107 Arctic sea-ice variability using an Earth system model Inventory and Spatio-temporal dynamics of glacial lakes in Dibang river basin of Eastern 11:55 - 12:00 Rayees Ahmed 6 Himalayas using combined approaches of Remote Sensing and GIS Assessing the status of glaciers in upper Jhelum basin of Kashmir Himalayas using Sentinel- 12:00 - 12:05 Syed Towseef Ahmad 4 2 earth observation data Sea-ice in the Weddell Sea sector of West Antarctica: Insights from ocean-atmospheric 12:05 - 12:10 Juhi Yadav 114 forcing Polar processing and Chemical ozone loss in the Exceptional Arctic winters of 2011 and 12:10 - 12:15 Raina Roy 202 2020

12:15 – 12:20 Kshitija S 349 An updated trends of global sea ice condition in a warming world

12:20 - 12:30 Break

PARALLEL SESSION 1 (Bharati Hall) Technical Session 16: Marine Geology and Geophysics (MGG) Session Chairman: Dr. K.A. Kamesh Raju, NCPOR Coordinators: Dr. Rajeev Saraswat, NIO & Dr. Mahesh B.S., NCPOR Invited Talk: 12:30 - 13:00 Prof. Jyotiranjan S Ray, NCESS, Thiruvananthapuram "Outstanding Research Questions in Indian Ocean Tectonics" 13:00 - 14:00 Lunch Break

Time Speaker Reg. No Title of Presentation Importance Of Geomorphological Characteristics In Determining Location Suitability For 14:00 - 14:15 A. Baskaran 204 Setting Up Desalination Plants Role of In-situ and Meteoric 10Be in Quaternary Glaciation, Marine Chronology and 14:15 - 14:30 Ravi Bhushan 282 Paleomagnetic Reconstruction Paleoclimate variability and global teleconnection during Northgrippian-Meghalayan stages

14:30 - 14:45 Upasana S. Banerji 303 from the Southern India 14:45 - 15:00 Juzer Shaikh 302 Role of Weathering and Reverse weathering in Global Carbon cycle : DAY 3 : DAY

15:00 - 15:15 Anjana Gireesh S 39 Boron isotope study of foraminiferal carbonate from the Arabian Sea

QUICK PRESENTATION (5 minutes) Quantification of basin-level air-sea carbon dioxide exchange across the _x000B_Mid 15:15 - 15:20 I V Satya Chanakya 216 Pleistocene Transition. Crustal architecture and tectonic evolution of the Western Ghats and status of the major 15:20 - 15:25 Zeba Nezrin F K 218 tectonic Shear Zones of Southern Granulite Terrain (SGT), and their offshore extension: An

14 August 2021 (Saturday) Integrated Geophysical approach Reconstruction Of Indian Monsoon Variability Since Last Glacial Maxima From The Bay Of 15:25 - 15:30 Nayana V Haridas 279 Bengal Paleoclimate and Sea-Level Variability during Holocene epoch from Coastal Lowland 15:30 - 15:35 Jithu Shaji 315 Sediments of Kerala, SW Indial Mg/Ca of marine carbonates as a paleotemperature proxy: A case study of the 15:35 - 15:40 Tejeswar Dash 81 southeastern Arabian Sea for the past 40 Kyrs Sarathchandraprasad 15:40 - 15:45 100 South Asian Summer Monsoon variability during the Mid-Piacenzian Warm Period T Intensification of Oyashio Current as Possible Cause for Reduction in the Western Pacific 15:45 - 15:50 Vikram Pratap Singh 50 Warm Pool during last 1 My: Planktic foraminiferal evidences from the Sulu Sea 15:50 - 15:55 Vikash Kumar 99 Southern Ocean link to Indian Monsoon Variability during the last Glacial Period Denitrification and hydrographic variability during Mid-Pleistocene Transition: Results from 15:55 - 16:00 Shubham Tripathi 104 IODP Expedition 355 16:00-17:00 Valedictory Function

PARALLEL SESSION 2 (Maitri Hall) Technical Session 14: Coastal and Open Ocean processes (COOP) Session Chairman Dr. Rashmi Sharma, SAC/ISRO Coordinators: Dr. Smitha Balraj, CMLRE & Dr. Bajish C.C., NCPOR Invited Talk: 09:30 - 10:00 Dr. Prakash Chauhan, IIRS/ISRO, Dehradun “Satellite Based Ocean Observing and the Blue Economy"

Time Speaker Reg. No Title of Presentation

10:00 - 10:15 Samiran Mandal 197 Surface circulation features in the western andaman sea: observations from hf radar

10:15 - 10:30 Shirin Jadhav 335 Phenology of Coastal Upwelling in the South Eastern Arabian Sea

10:30 - 10:45 Subhasis Pradhan 182 Future projection of wave characteristics using cmip6 wind along south odisha coast Source and Fate of Anthropogenic Particles in a Transitional Environment from 10:45 - 11:00 Gokul Valsan 289 Southwestern India 11:00 - 11:15 Guru Prasath 211 Sustainable Management Of Shoreline Near Mahabalipuram Spatio-temporal variations in the current pattern associated with Oceanic South Eastern 11:30 - 11:45 Arun V.S 326 Arabian Sea

11:30 - 11:45 Tea Break DAY 3 QUICK PRESENTATION (5 minutes)

11:45 - 11:50 G Giridhar 17 Experimental Study on Wave Transmission and Run-up over Submerged Vegetation Trends In Tropical Cyclone Rainfall Over The Bay Of Bengal During The Past Two 11:50 - 11:55 Harikrishnan R 134 Decades Wave transformation and attenuation along the central Kerala coast of India using Mike 21 11:55 - 12:00 Vasudevan Shankar 136 SW Model Modulation of boundary layer parameters in association with tropical cyclones over the Bay

14 August 2021 (Saturday) : 12:00 - 12:05 Arjun S Nair 314 Of Bengal Assessment of Nutrient Bioavailability and Trophic Status of Beypore Estuary, Southwest 12:05 - 12:10 Rose Santhosh 92 India

12:10 - 12:15 Prerana Prakash Shet 266 Dinoflagellate cyst distribution along the Karwar coast: a HAB perspective

12:15 - 12:20 Abdul Azeez S 259 Sound speed variation in the coastal waters of Kochi and signature of subsurface maxima

12:20 - 12:25 Unnikrishnan K 310 Coastal Risk Assessment of Alappuzha district in Kerala, India

Mesoscale circulation features on the northwestern bay of bengal using hf radars 12:25 - 12:30 Anupama Sahoo 173 observations Vishnu Narayanan Physical settings and biogeochemical response of oceanic front along the coastal waters 12:30 - 12:35 294 Nampoothiri S off Mangalore, West Coast of India

12:35 - 12:40 Navin Chandra 234 Characteristics of mesoscale eddies in the Bay of Bengal using a numerical model

Observations of currents in the Sri Lankan dome using in-situ, satellite, and re-analyzed 12:40 - 12:45 Athira K 191 data.

13:00 - 14:00 Lunch Break

PARALLEL SESSION 2 (Maitri Hall) Technical Session 17: Mathematics in Ocean Science (MOS) Session Chairman Dr. C. Gnanaseelan, IITM Coordinators: Dr. Kunal Chakraborty & Sh. S. Chatterjee, NCPOR

Time Speaker Reg. No Title of Presentation

DAY 3 A study of mixing and biological activity in the Arabian sea using Finite Size Lyapunov 14:00 - 14:15 Jai Kumar 322 exponents 14:15 - 14:30 Abhijith Raj 62 Evaluation of the best performing WaveWatch III model setup for the Indian Ocean. Cubic Spline Polynomial As Input Energy Spectrum For Determining The Nonlinear Energy 14:30 - 14:45 Vaishnavi S 130 Transfer Rates In A Wave Spectrum. 14:45 - 15:00 Srinivas Bolem 235 Applications of AI/ML in Fish Biomass Estimation System Assessment of CMIP6 models’ skill for tropical Indian Ocean sea surface temperature 15:00 - 15:15 Subrota Halder 258 variability 14 August 2021 (Saturday) : Mayur Gajanan 15:15 - 15:30 348 Using Machine Learning To Characterize Ocean Basins Sapkal Sea Surface Temperature Projection for the Bay of Bengal under RCP8.5 using 1D PWP 15:30 - 15:45 Hitesh Gupta 221 Model

16:00 - 17:00 Valedictory Function

PARALLEL SESSION 3 (Himadri Hall) Technical Session 15: Ocean Engineering and Technology (OET) Session Chairman Prof. Prasad K Bhaskaran, IIT-KGP Coordinators: Dr. Jossia Joseph, NIOT & Dr. R Srivastava, NCPOR Invited Talk: 09:30 - 10:00 Dr. GA Ramadass, NIOT, Chennai “Technology for exploration of Ocean Resources”

Time Speaker Reg. No Title of Presentation

10:00 - 10:15 Dr. Rameesha T V 47 Experimental Study on the Maneuvering of a Container Ship in Regular waves

10:15 - 10:30 Sreelakshmi S 54 Variability and distributional analysis of extreme swell wave energy flux in the Indian Ocean

10:30 - 10:45 B.Kesavakumar 88 Air Quality Monitoring from Deep Ocean Moored buoy systems in the Indian Ocean

10:45 - 11:00 Ashwani Vishwanath 94 Ocean observation buoy powered using wave energy

11:00 - 11:15 Prabin Kumar Kar 147 Erosion and accretion pattern and shoreline change near Gopalpur port, East coast of India Effect of Mooring Motion on Temperature Profile Measurements in OMNI Buoy Systems: A 11:15 - 11:30 Biswajit Haldar 105 Case Study

11:30 - 11:45 Tea Break DAY 3 Understanding the Pressure Measurement in multi-phase of Open Cycle OTEC power 11:45 - 12:00 Biren Pattanaik 205 Plant 12:00 - 12:15 N Rama Krishnan 206 Longterm Shoreline Changes Along Kanyakumari Coast Using Geo Spatial Techniques

12:15 - 12:30 J. Sriganesh 229 Shoreline Changes Of Devaneri Coast, Tamilnadu, India

12:30 - 12:45 Suganya S 239 Challenges in Design of Intake Structure in Remote Islands 14 August 2021 (Saturday) : 12:45 - 13:00 Sondi Sudheer 241 Monopile Supported Trestles for Intake and Outfall Systems at Remote Islands

13:00 - 14:00 Lunch Break

Technical Session 18: Ocean Engineering and Technology (OET) Session Chairman Dr. R. Venkatesan, NIOT Coordinators: Dr. Sourav Mandal, NIO & Mr. Prasad Dudhgaonkar, NIOT

14:00 - 14:15 Mounika Mallela 242 Performance of Monopile Platforms during Service Life

14:15 - 14:30 Srinivasan R 318 Conductivity Sensor For Marine Applications Based On Capacitive Coupling Technique

14:30 - 14:45 Sarojani Maurya 321 Development of Autonomous Underwater Profiling Drifter

14:45 - 15:00 Rajkumar. J 323 Sensitivity analysis of wave hindcasts for the design criteria for engineering applications

15:00 – 15:15 S Muthukumaravel 325 Design and Development of automatic open sea hybrid submerged fish cage system

16:00 - 17:00 Valedictory Function

Author Index

Acharyya N., 16, 18, 19, 45, 104, 213, 222 T., 40, 50 Anjana Adhikari G. S., 157 A., 110 Anju Agarwal M., 38 N., 229 Anshath Neeraj, 127 H.N., 108 Nishtha, 77 Anu Aguiar G., 21 A., 111 Anurose Ahmad T. J., 113 S. T., 210 Anusree Ahmed A., 66 R., 211 Aodi Ajay A., 43 S., 167 Ardra Ajayakumar D., 98, 218 P., 165 Arjun, 80 Akalesh,9 Arun Akhil V.S., 146 V. S., 51 Aruna Kumar Albert K.A. , 95 J., 68 Arunbabu Alex E., 184 M.J., 123, 130 Asha Devi Ali C. R., 144 I., 219 Ashwani Alluri V. , 181 S.K.R., 196–198, 207 Asutosh Amrutha A., 104 K., 139 Athira Anand K, 119 A., 70 Avinash P., 108, 178 K., 214, 215 T.,9 Azeez Anil A.S., 136 A.C., 36 Anilkumar Baag K., 51, 206 S., 73

245 Mathematics in Ocean Science

Babu S., 227 C.A., 90, 92 Bonthu N., 41 S., 147, 148 Badia Bragath A., 121 R.C., 124 Bajish C.C., 16, 222 Carpenter Balamurugan L., 121 R., 186, 189 Castillo Balasubramanian J.M., 128 S., 154 Chacko Banerji R., 19 U. S., 166, 169, 170 Chakraborty Baranval A.,7, 114 N., 81 P., 26, 39, 45, 117 S., 26 Barik Chaluvadi S., 187 R., 85 Baskaran Chanakya A., 163 I.V.S., 164 Behera Chance A.K., 23 R., 121 B., 187 Chandra P. , 76 N., 131 Bell Chandramohan, 125 T., 122 P., 124, 163, 191 Bepari Chavan K.F., 141 S. P., 212 Bhaskar Chennuri J.T., 22, 216 K., 26, 117 P.V., 22, 216 Choudhary Bhaskaran R.K., 229 P.K., 67, 68, 147, 148, 175 Chowdary Bhatawadekar J. S., 87, 228 V.C., 34 Chowdhury Bhattacharya M., 31 B., 13 S., 28 D’Costa Bhaumik P. M., 45, 48, 52, 137 S., 37 Damare Bhushan Samir R., 29, 34, 35 R., 167, 169, 170 V. S., 53, 54 Bikram Darbha R., 141 G. K., 11 Biswas Darsana H., 31–33, 47 K.K.,6, 14 Bolem Das

246 Mathematics in Ocean Science

A., 126 H., 52 B., 78 Gauns S., 28 M. U., 46 Dasgupta Gawade P., 70 L., 17 Dash George T. , 159 B., 201 Deb C., 102 P., 105 J.P., 111 Deepa J.V., 213 J.S. , 79 R.V., 176 Deepulal Ghose P. M., 51 M., 24 Deshpande S.K., 134 M., 133 Ghosh Dessai S., 43 D.V.G., 16 Ghoshal Dey T., 114 S., 112 Giridhar Dharani G., 96 G., 204, 227 Gnanaseelan Dhorde C., 79, 87, 228 A., 78 Gopikrishnan Dias G. S., 10 B., 53 Gopinath Divya David A., 40 T., 220 Gowthaman V., 204, 205 Elizabeth Gupta S.N.X., 199 A., 128, 219 Emmanuel G.V.M., 141 R., 133 H., 226

Farooq Haimbala S.H., 28 V.N., 188 Fernandes Haldar V., 45 B., 183 Fernandez Halder D.R., 119, 152 S., 88, 228 Hamza Gal´ı F., 38 M., 122 Haragi Ganesh S., 56, 57, 137 A., 96 Haridas Gangopadhyay N. V., 166 A., 120 Harikrishnan Gaonkar K., 51

247 Mathematics in Ocean Science

M., 119, 151 G.,9 R., 106, 133 Joao Harit M. H., 47 A.K., 41 John Hatha C.R.E.,5, 12 M. A. A., 142 Joseph Hulswar K.J., 135, 149, 153, 183 S., 101, 122 Joshi Hussain A.P., 74, 100 M. S., 142 K. B., 170 Joy Idayachandiran V., 151, 152 G., 42 Jyothibabu Ihjas R., 216 K., 102 Inamdar Kadam S., 97, 121, 122 S.S., 69 Ingle Kalyani S.T., 85 M., 149 Ingole Kamalakannan B.S., 63 B., 55, 59, 60 Ishita Kar I., 26 P.K., 115, 187 Karati Jacintha K. K., 144 T. G. A., 89 Karthikeyan Jadhav A., 181 S., 150 S., 163 Jaganmohan Katyal J., 42 R., 198 Jalan Keerthivasan S. , 105 R., 186 Jalihal Kerkar P., 181, 190 A.U., 15, 16, 18, 81 Janakiram Kesavakumar R., 189 B., 179, 220 Janani Khadanga R., 193 M.K., 20, 23, 55, 59, 60 Jawak Khadge S., 216 N.H., 26 Jayachandran Kranthi S., 117 M. G., 133 Jena Krishnan B., 222 A., 67 B.K., 55, 59, 60, 95, 203 N.R., 191 P. S., 167 Krishnankutty Jeyasekaran P., 174

248 Mathematics in Ocean Science

Krishnaveni G., 182 M., 193 Mallela Kshitija M., 198 S., 222 Mallissery Kulkarni A., 61 A., 228 Mandal, 194 Kumar S., 73, 118, 120 A., 132 Manjebrayakath B. P., 224 H., 144 B.S., 192 Manohar J., 229 C.S., 24 J.V., 163 Martin P., 67, 218 M., 111 V., 74, 100 M.V., 153 Vikash, 160 Mathew D.S., 58 B., 83 Kurian M. V., 135 P.J., 63 P.T.,5,6, 12, 14 Kushwaha Mathur P., 84 M., 229 Kuttippurath Maurya J.,7, 10, 98, 218 S., 202 Maya Lahiri K., 166, 169, 170 S.P., 116 Mayur Lana S., 230 A., 122 Meenakshi, 48 Latha Menon G., 182, 184–186, 189, 193 H.B., 101, 110 Lewis Merin H., 128 C.A., 206 Li Q., 121 Minu Linsha P., 16, 81 L. C., 140 Mishra Lokhande A.K., 128 S., 182 P., 58 R.K., 18, 19, 27, 45, 81 Madhu Misra M., 197 S., 164 Mahajan S.K., 124 A.S., 97, 121, 122 Mitbavkar Mahale S., 36 R., 27 Mitra Maheswaran A.K., 111, 128, 214, 219 P.A., 151 Mohan Malarkodi M. C., 54

249 Mathematics in Ocean Science

R., 215 A., 213 Mohanta Nasar S.K., 184 T., 180 Mohanty Naseef M.M., 115 T.M., 203 P.K., 82, 115, 187 Navaneeth S., 13 K.N., 135, 153 Moharana Nawab S.S, 109 I., 134 Momin Nezrin I.M., 111, 128 Z.F.K., 165 Moraskar Niji S.S., 44 T.Y., 152 Mounika M., 196 Ovhal Mujumdar S., 129 M., 85 Padalkar Muni Reddy P., 26, 117 M.G., 96 Padhi Murali S.R., 82 K., 192, 200 Padmalal Murthy D., 166, 169, 170 M.V.R., 58, 95, 126, 138, 196–198, 207 Panda Muthiah M., 103 M.A., 179, 183, 220 U.S., 58, 126 Muthukumaravel Pandey S., 204, 227 Medhavi, 47 Muthvel V.K., 77 P., 202 Pandi S.R., 16 Naik Pant A., 56, 57 V., 116, 131, 214, 219 R.K.,4, 15, 19, 27, 45, 137 Parab Nair A.S., 24 A., 227 Parekh A. S., 145 A., 87, 228 N.R., 199, 206 Parvathy Nampoothiri A., 86 V.N.S., 141, 144 M., 91 Nanajkar Patekar M., 137 D., 87 Nandhini Pathak D., 200 K.N., 99 Narayan Patil A. V., 139 A.P., 110 Narayanan J.S., 25, 30

250 Mathematics in Ocean Science

S., 137 Raj Patra A., 224 S., 15, 81 S., 218 Patro S.A.S, 207 S., 20, 23 Rajaguru Pattanaik S., 204 B., 181, 190 Rajavanshi Pattanayak I., 123 A.A., 55, 59, 60 Rajith Paul K, 119 F.P., 113 Rajkumar P., 25 J., 203 Pednekar Raju S. M., 221 R.P., 152, 178, 199 Periasamy S.K., 126, 138 R., 63 Ram Peter K., 121 R.,7 Ramachandran Prabhakar R., 113 V., 225 Ramadass Prabhakaran G.A., 201 M., 163 RamaKrishna Prabhu S.S.V.S., 177 S., 139 Ramasamy Pradeep E.V., 41 A., 195 Rameesha Pradhan T.V., 174 S., 115, 187 Ramya U., 58 P. G., 224 Prajeesh Rani A.G., 61, 154 D.M., 102 Prasad Rao C.A., 135, 153 A.D., 185 G.S., 205 R. A., 51 Prasath V.T., 123, 130 J.G., 124, 125, 191 Y.V.N., 181, 190 Princy Rasheed M.J., 21 K., 141, 144 Priya Rath V., 21 Priyaa A.R., 36 S.S., 95 D., 20 Ratheesh Radhika S., 127 R. S. R., 89 Raulo Rahaman S., 50 W., 157 Ravichandran

251 Mathematics in Ocean Science

M., 220 S.A., 192, 195 Ray Santhanakumar A., 118, 194 J., 204 S., 134 Sarangi Reji S.K. , 103 M.J.K., 90 Saranya Renjith J.S., 70 K.R., 102 Sarathchandraprasad Reshma T. , 161 M.S., 147, 148 Sarkar T., 92 A., 15, 19, 81 Rodrigues D., 39 RV., 30 S., 75 Rose Satheesan S., 102 G.,6 Roshny Satheeshan S., 113 G., 14 Roxy Satheeshkumar M. K., 43, 66, 70, 86, 91, 106, S., 151 133, 143 Sawant Roy P., 137 R., 218 Sekar S., 194 P., 196, 198 Sabu Senthilkumar P., 15, 19, 81, 104, 213, 217 P., 183 Sadaiappan Shafeeque B., 46 M., 144, 150 Sagar Shah M., 197 S., 35 Saheed Shaiju P.P., 219 S.S., 16 Sahoo Shaikh A., 112 A. A., 101 Saiz-Lopez J., 168 A., 121 N., 101 Sajeev Shaji K.S, 181 J., 169, 170 R., 83, 107, 199 Shakila Samal R.J.,9 D.V., 69 Sharma R.N., 115 D., 32 Sandhya R., 127, 229 S. V., 49 Shastri Sanjana N., 99 M.C., 184 Shet Sannasiraj P., 137

252 Mathematics in Ocean Science

Shikha Subeesh S., 230 M.P., 217, 220 Sil Subrahamanyam S., 28, 112, 118, 120, 194, 226 D. B., 113 Silori Sudarsanarao S., 33 P., 15 Simo Sudhakar R., 122 T., 201, 202, 205, 227 Simon Sudheer E.K., 83 A. K., 169 Singh S., 197 A. K., 158 Sudheesh Archana, 220 V., 141 C., 13 Suganya K.S., 147, 148 S., 196, 197 S., 40, 50, 154 Sunanda V. K., 133 N.,7 Vikram P., 158 Sundar V., 195 Sinha Sundaramoorthy A.K., 22 S., 42 Devesh K., 158 Suneel Sitlhou V., 123, 130 L., 26, 117 Suraj Smitha R., 214 B.R., 38, 142, 144, 146, 150 Surendran Soares S., 62 M.A., 19, 27 Surisetty Sona V.V., 132 Swain M.A., 108 D., 109, 134 Sreejith M., 72, 224 Tandon Sreelakshmi A., 183 S., 175 Tarique Sreerag M., 157 A., 27 Thalayappil Sreevidhya S.R.S.,5,6, 12, 14 R.,8 Thankachan Sriganesh A., 147, 148 J., 89, 195, 200 Thatiparthi Srimani K., 147, 148 R.,4 Thomas Srinivasan A., 173 R., 177, 201 A.P., 123, 130, 217 S., 55, 59, 60, 182 D., 62 Srivastava Thulasidharan R., 104 N.,5, 12

253 Mathematics in Ocean Science

Tinel V., 15, 18, 19 L., 121 Venkatesan Tiwari R., 118, 135, 149, 153, 179, 183, M., 76, 159–162 186, 189, 193, 220 Y. K., 88 Verma Tripathi N., 227 S., 162 Vibin Tripathy M.V., 108 S.C., 15, 16, 81 Vijay Trivedi P.C., 180 A., 75 Vijayan A.K., 141 Unnikrishnan Vikranth K., 143 T., 177 Vaishnavi Vishnu S., 225 M., 21 Valsala R., 140, 145 V., 38, 61, 88, 154 Vivek Valsan B., 102 G., 139 Warde Vankara K., 137 V., 17 Warrier Varghese A. K., 139 A., 178 Warrior Varikoden H.V., 74, 100 H., 85, 90, 92, 140, 145 Waters Varthini J., 111 D.S., 126, 138 Vasa Yadav N.J., 62 J., 215 Vasudevan R.K., 71 S., 107 Yadidya Vengatesan B., 185 G., 179 Yovan Venkataramana L., 139

254 SeventhSeventh NaNationaltional ConferConferenceence ofof thethe OceanOcean SocietySociety ofof IndiaIndia

Organised by: National Centre for Polar and Ocean Research (NCPOR), Ministry of Earth Science (MoES), Goa and Ocean Society of India (OSI)