Geophysical Constraints on Structure and Tectonics of the Eastern Arabian Sea and the Adjoining West Coast of India with Special Reference to the Kerala Basin

The main objective of the present study is to model the gravity fields in terms of lithospheric structure below the western continental margin of India (WCMI) identify zones of crustal mass anomalies and attempt to infer the location of Ocean Continent transition in the Arabian Sea. In this study, the area starting from the western shield margin to the region covering the deep oceanic parts of the Arabian Sea which is bounded by Carlsberg and Cerg and Central Indian ridges in the south, eastern part of the Indus Cone in the west and falling between 630E and 800E longitudes, and 50N - 240N latitudes has been considered. The vast amount of seismic reflection and refraction data in the form of crustal velocities, basement configuration and crustal thicknesses available for the west coast as well as the eastern Arabian Sea has been utilized for this purpose

Nutrient Dynamics in the EEZ of the West Coast of India with Special Reference to the Oxygen Minimum Zone and Denitrification

The present work aims at deciphering the processes that control the nutrient distribution along the EEZ (Exclusive Economic Zone of India) of the west coast of India and to bring out its linkage with primary and secondary productivity. This work assume utmost importance as very few studies have hitherto focused entirely on the EEZ of the west coast of India to address the biochemical responses brought about by monsoons. The present study examines the seasonal variations in physicochemical parameters and associated primary biological responses along the west coast of India. This study targets to measure and understand the shelf ocean exchange in a typical coastal upwelling region of the southeast Arabian Sea, and the influence of convective mixing along the northern part of the west coast of India. The study focuses more directly on coastal upwelling along the southwest coast of India, within the EEZ. The effects of coastal upwelling, eddy formation and the offshore advection are apparent in the present investigation. This has consequences to fisheries and climate, in energy transfer to the food chain and the increased sequestering of carbon in the ocean. The study also focuses on the Oxygen Minimum Zone (OMZ) and dentrification observed along the EEZ of the west coast of India on a seasonal scale. In the study, an attempt is also made to demarcate the geographical boundaries of the denitrification zone in the EEZ of India and on the nature and magnitude of these variations, on a seasonal and inter annual scales

Dynamics of Infaunal Benthic Community of the Contenental Shelf of North-Eastern Arabian Sea

In this study dynamics of infaunal benthic community of the continental shelf of north-eastern Arabian sea. The benthic (under water sea) organisms play an important role in the marine food chain. It can be concluded that seasonal differences in the benthic community was observed in lower depths and absent in deeper depths. Increased richness and diversity during pre-monsoon may be related to the increased primary production which inturn influenced by the increased nutrient input due to winter convection. No single ecological factor could be considered as a master factor. In general the area supports moderately high benthic production and diversified community.

Biogeochemistry of trace metals in the Indian EEZ of the Arabian Sea and Bay of Bengal

The present study has been initiated to unravel the distribution of trace metals and its geochemical behavior in the Indian EEZ of the Arabian Sea and Bay of Bengal. Trace metal accumulation in aquatic consumers is of interest to ecologists and environmentalists so as to understand the fate and effect of contaminants in the food web dynamics and the biogeochemical cycling of trace metals. It is well established that oceanic distribution of macronutrients such as nitrate, phosphate and silicate provide critical to biological growth and related geochemical processes. In this study it can be inferred, that there is a need for a better understanding of background informations on trace metal concentrations with respect to space and time and their fluctuations in the Arabian Sea and Bay of Bengal zooplankton. Without a sound knowledge on spatio-temporal fluctuations, it will be impossible to differentiate anthropogenic metal inputs from natural background concentrations with a routine biomonitoring programme. Fe, Cu, Zn, Cd & Pb showed a slight enrichment in zooplankton from the Arabian Sea during spring intermonsoon compared to intermonsoon fall. The relative enrichment of Fe, Cu & Zn in zooplankton from the Arabian Sea during intermonsoon spring than intermonsoon fall was due to favourable bioaccumulation factors of these elements during this season. Nevertheless this study can be looked upon as a starting point for further investigations on these biogeochemically important processes, which are vital in addressing the dynamics of productivity of waters.

Interannual Variability of Upwelling Indices in the Southeastern Arabian Sea: A Satellite Based Study

Increase in sea surface temperature with global warming has an impact on coastal upwelling. Past two decades (1988 to 2007) of satellite observed sea surface temperatures and space borne scatterometer measured winds have provided an insight into the dynamics of coastal upwelling in the southeastern Arabian Sea, in the global warming scenario. These high resolution data products have shown inconsistent variability with a rapid rise in sea surface temperature between 1992 and 1998 and again from 2004 to 2007. The upwelling indices derived from both sea surface temperature and wind have shown that there is an increase in the intensity of upwelling during the period 1998 to 2004 than the previous decade. These indices have been modulated by the extreme climatic events like El–Nino and Indian Ocean Dipole that happened during 1991–92 and 1997–98. A considerable drop in the intensity of upwelling was observed concurrent with these events. Apart from the impact of global warming on the upwelling, the present study also provides an insight into spatial variability of upwelling along the coast. Noticeable fact is that the intensity of offshore Ekman transport off 8oN during the winter monsoon is as high as that during the usual upwelling season in summer monsoon. A drop in the meridional wind speed during the years 2005, 2006 and 2007 has resulted in extreme decrease in upwelling though the zonal wind and the total wind magnitude are a notch higher than the previous years. This decrease in upwelling strength has resulted in reduced productivity too.

Coastal Upwelling of the South Eastern Arabian Sea - An Integrated Approach

Upwelling regions occupies only a small portion of the global ocean surface. However it accounts for a large fraction of the oceanic primary production as well as fishery. Therefore understanding and quantifying the upwelling is of great importance for the marine resources management. Most of the coastal upwelling zones in the Arabian Sea are wind driven uniform systems. Mesoscale studies along the southwest coast of India have shown high spatial and temporal variability in the forcing mechanism and intensity of upwelling. There exists an equatorward component of wind stress as similar to the most upwelling zones along the eastern oceanic boundaries. Therefore an offshore component of surface Ekman transport is expected throughout the year. But several studies supported with in situ evidences have revealed that the process is purely recurring on seasonal basis. The explanation merely based on local wind forcing alone is not sufficient to support the observations. So, it is assumed that upwelling along the South Eastern Arabian Sea is an effect of basin wide wind forcing rather than local wind forcing. In the present study an integrated approach has been made to understand the process of upwelling of the South Eastern Arabian Sea. The latitudinal and seasonal variations (based on Sea Surface Temperature, wind forcing, Chlorophyll a and primary production), forcing mechanisms (local wind and remote forcing) and the factors influencing the system (Arabian Sea High Saline Water, Bay of Bengal water, runoff, coastal geomorphology) are addressed herewith.

Dynamics and Thermodynamics of the Arabian Sea Warm Pool

The present study examines the importance of low saline waters and resulting barrier layer in the dynamics of the ASWP using observational data.The oceanic general circulation models (OGCM) are very useful for exploring the processes responsible for the ASWP and their variability. The circulation and thermohaline structure stimulated by an OGCM changes a lot when the resolution is increased from mesoscale to macro scale. For a reasonable simulation of the ASWP, we must include the mesoscale turbulence in numerical models. Especially the SEAS is an eddy prominent region with a horizontal dimension of 100 to 500 km and vertical extent of hundred meters. These eddies may have an important role on the evolution of ASWP, which has not been explored so far.Most of the earlier studies in the SEAS showed that the heat buildup in the mixed layer during the pre-monsoon (March-May) is primarily driven by the surface heat flux through the ocean-atmosphere interface, while the 3-dimensional heat budget of the ML physical processes that are responsible for the formation of the ASWP are unknown. With this background the present thesis also examines the relative importance of mixed layer processes that lead to the formation of warm pool in the SEAS.

Biochemical & Pharmacological evaluation of liver oils of selected deep sea sharks and chimaeras of the Indian EEZ

With a seacoast of 8,1 18 km, an exclusive economic zone (EEZ) of 2 million square km, and with an area of about 30,000 square km under aquaculture, lndia produces close to six million tonnes of fish, over 4 per cent of the world fish production. While the marine waters upto 50m depth have been fully exploited, those beyond, remain unexplored. There is an ever increasing demand for fishery resources as food. The coastal fishery resources of the country are dwindling at a rapid pace and it becomes highly imperative that we search for alternate fishery resources for food. The option we have is to hunt for marine fishery resources. Studies pertaining to proximate composition, amino acid and fatty acid composition are essential to understand the nutraceutical values of these deep sea fishery resources. The present study was aimed to carry out proximate composition of deep sea fishery resources obtained during cruises onboard the FORV Sarise Sampada, to identify fishery resources which have appreciable lipid content and thereby analyse the bioactive potentials of marine lipids, to study the amino acid profile of these fishery resources, to understand the contents of SPA, MUFA and PUFA and to calculate the n3/n6 fatty acid contents. Though the presence of nutraceuticals was identified in the marine fishery resources their use as potential food resources deserve further investigation. So the study were carried out to calculate the hepatosomatic indices of sharks & chimaeras and conduct biochemical characterisation of liver oils of Apristurus indicus, Cenlrophorus scalprams, Centroselachus crepidater, Neoharriotta raleighana, and Harriotta pinnata obtained during cruises onboard the FORV Sugar Sampada.Therapeutic use of shark liver oil is evident from its use for centuries as a remedy to heal wounds and fight flu (Neil er al. 2006). Japanese seamen called it 'samedava' or "cure all". Shark liver oil is being promoted worldwide as a dietary supplement to boost the immune system, fight infections, to treat cancer and to lessen the side effects of conventional cancer treatment. These days more emphasis is laid on the nutritive benefits of shark liver oils especially on the omega 3 polyunsaturated fatty acids ( PUFAs) (Anandan er al. 2007) and alkylglycerols (AKGs) (Pugliese er al. I998) contained in them due to the high rise of inflammatory disorders such as arthritis, asthma and neurodegenerative diseases like Alzheimer’s, Parkinson’s and Schizophrenia. So the present study also evaluate the pharmacological properties with respect to analgesic, anti-inflammatory, anti pyretic and anti-ulcer effects of four different liver oils of sharks belonging to the Indian EEZ and to identify the components of oil responsible for these activities.The analgesic and anti-inflammatory activities of liver oils from Neoharriotra raleighana (NR), Centrosymnus crepidater (CC), Apristurus indicus (AI), and Centrophorus sculpratus (CS) sharks caught from the Arabian Sea and the Indian Ocean were compared. The main objectives also include determination of the cholesterol lowering effects of liver oils of Neoharriotra raleighana (NR) and Centrophorus sculpratus (CS) on the high fat diet induced dyslipidemia and to compare the impact of four isolipidemic diets, on levels of serum diagnostic marker enzymes, on lipid profile of blood and liver and antioxidant status of heart in male Albino rats. And also to study the efficacy of Centrophorus sculpratus (CS) liver oil against Complete Freund’s Adjuvant-induced arthritis and to compare the anti-inflammatory activity of this oil with a traditionally used anti-inflammatory substance gingerol (oleoresin extracted from ginger.). The results of the present study indicated that both (Centrophorus sculpratus liver oils as well as gingerol extracts proved to be effective natural remedies against CFA-induced arthritis in Albino rats.

Macrobenthosof the cotinental margin(200-1000 m) of South Eastern Arabian Sea with special reference to Polychaetes

This thesis Entitled macrobenthos of the continental margin (200-1000m) of south eastern arabian sea with special reference to polychaetes. The continental margins are geologically complex and hydrodynamically active regions of the ocean, where vital biogeochemical processes take place from a global perspective. The Eastern Arabian Sea is one of the most productive regions of the world, and as a result, vast amount of organic matter is supplied to the sub surface waters and sea bed of the Arabian Sea. In this study, data on faunal abundance, standing crop and faunal composition, together with sedimentary and environmental parameters were collected from three depths (200m, 500m & 1000m) in nine bathymetric transects along the South Eastern Arabian Sea (from Cape Comorin to Karwar) during three surveys. In the present study, five textural classes of sediments were identified from the SEAS margin, viz. sand, silty sand, sandy silt, clayey silt and admixture of sand, silt and clay. The composition of sand was higher in the southern region and decreased progressively towards the north. On the shelf edge and upper slope regions in the south (Cape to Kollam) in particular, sandy sediments dominated .

Studies on the Biology, Ecology and Fishery of the sea cucumber Holathuria (hetriatyla) scabra (Jaeger) from southeast coast of India

The distribution of the holothurian H. KH.) scabra indicated its availability all along coastal areas on Palk Bay from Rameswavam to Mallipattinam and along the Gulf of Hannah coast from Pamban to Ervadi and Tuticmhin,'at 4~2O m depth.The major fishing for holmthurians was done by skin diving at all the centres. The tallu valai was operated at Tuticorin and Vedalai and trawlevs were operated at Rameswaram.The fmod of H. KN.) scabra consists of ovganic matter which contains mud, sand, shell debris, bivalves and algae. Obsehvatinns indicated the species seems to be a n0n—se1ective feeder. The assimilation efficiency from sediment to faeces indicated that the faecal pellets of H. KH.) scabra are semidigested.A multiple relationship was fitted between total length, total weight, gutted weight, gonad weight and maturity stages were found significant.The fishing season for holothurians commences from October to March along Gulf of Manner coast and from March to October along Palk Bay coast.The percentage of catches recorded by skin diving, trawlere and tallu valai were 80.04%, 10.27% and 9.69% respectively. Skin diving contributes to maximum catch.The holothurians landed all along the Gulf of Manner and Palk Bay coasts constitute 25.6% and 74.4% respectively. This showed that Palk Bay coast is more productive.

Water characteristics and current structure of the intermediate waters in the arabian sea

At intermediate depths of the Arabian Sea, the circulation and characteristics of water are more influenced by the high saline waters from the north and low saline waters from the south of equator. The interaction of these waters which greatly differ in characteristics is less understood compared to that at the upper layers. An understanding of the nature of the intermediate waters is of vital importance not only because of the unusual characteristics of the waters but also due to the influx of the different water masses from the neighbouring Red Sea and Persian Gulf. Hence, in the present investigation, it is proposed to study the water characteristics and current structure of the intermediate waters in the Arabian Sea through the distribution of the water properties on the isanosteric surfaces of 100, 80, 60 and 4O—cl/t, vertical sections, and scatter diagrams An attempt is also made to present the potential vorticity between different steric levels to understand the circulation and mixing processes. Data collected during and subsequent to International Indian Ocean Expedition (IIOE) are used for this study. The thesis has been divided into six chapters with further sub divisions

Studies on some fish larvae of the arabian sea and bay of bengal

Though several scientific expeditions surveyed tha Indian ocean. their findings on larval fishes were fragmentory and incomplete. During the International Indian ocean expedition (1960-1965) zooplankton samples were collected from vast area at the lndian ocean adopting standard procedures by participating vessels. These planktons provided an opportunity for a general study of the zooplanltton as well as their anotomy. abundance and distribution.. Realising the imortance of the analysis and classification of fish larvae at the family level being one of the most important information required then for the Indian Ocean region the fish larval portion sorted out from the above zooplankton samples was allocated to the author by the UNESCO consultative committee for the Indian Ocean Biological centre. In spite of the emhasis laid on The study of the family scombridae. owing to the paucity of the scombridae material in tne collection. much could not be done about it.However the record and description of the very early stages of morakel larvae made in 1967 as part of this study was the first of its kind. The present study on the distribution aspects o fish larva of such large area in the Indian ocean is also unique and first of its kind