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Global climate change affects the oceanographic features and distribution of marine fishes as they are poikilothermic animals. Study of oceanographic variables in a localized region is more relevant in the context of ecological responses rather than global or continental variations. In this study, time series analysis of chlorophyll-a concentration (Chl-a) in sea water and sea surface temperature (SST) was performed separately for southern, middle and northern stratum along south-west coast of India using various statistical tools. The SST showed an increasing trend along the entire south-west coast of India after the year 1995. The northern and southern stratum of south-west coast were highly influenced by rising SST, whereas middle stratum in present scenario showed stable conditions in terms of Chl-a concentration. The study provides a baseline information about changing patterns of oceanographic features along the south-west coast of India giving a better understanding of changing global climatic conditions in coastal ecosystems. [ABSTRACT FROM AUTHOR]

Shafeeque, M.; Shah, P.; Platt, T.; Sathyendranath, S.; Menon, N.N.; Balchand, A.N., and George, G., 2019. Effect of precipitation on Chlorophyll-a in an upwelling-dominated region along the west coast of India. In: Jithendran, K.P.; Saraswathy, R.; Balasubramanian, C.P.; Kumaraguru Vasagam, K.P.; Jayasankar, V.; Raghavan, R.; Alavandi, S.V., and Vijayan, K.K. (eds.), BRAQCON 2019: World Brackishwater Aquaculture Conference. Journal of Coastal Research, Special Issue No. 86, pp. 218–224. Coconut Creek (Florida), ISSN 0749-0208. The South Eastern Arabian Sea (SEAS) is an upwelling-dominated region, where the seasonally-reversing winds and currents are the major physical forces driving primary production. The region is characterized by high primary productivity during the summer monsoon season (June to September), when the winds and currents favor upwelling. The coast is notable for the presence of monsoonal rivers. During summer monsoon, nutrient-rich riverine water is discharged in great quantity into coastal waters. The heavy inflow of turbid, nutrient-rich water into coastal regions during the summer monsoon facilitates primary production, augmenting phytoplankton biomass. In the present study, we investigated the relative roles of upwelling and precipitation that drive productivity along the south-west coast of India. The available remote sensing data sets for chlorophyll-a (Chl-a), precipitation, silicate and wind were used for the period 1998 to 2016. The Chl-a anomaly showed positive correlation with upwelling index and precipitation except during 2003 and 2012. During these years, negative anomalies for Chl-a and precipitation were observed even though the upwelling index showed positive anomalies. So the enhancement in Chl-a was nominal during those specific years even when the upwelling was very strong. This indicates the role of riverine nutrients from heavy precipitation during summer monsoon that contributes significantly to coastal productivity apart from upwelling in SEAS. [ABSTRACT FROM AUTHOR]

The impact of coastal pollution was studied using edible oysters, Crassostrea rivularis as an indicator at two sites viz., North Wandoor (NW) and Phoenix Jetty (PJ) in Port Blair, Andaman. The hydrographic parameters showed that nitrite, nitrate and phosphate concentration were less and dissolved oxygen were more at NW compared to PJ. The oysters were collected from the study sites and biochemical, microbial, mineral profiles and ATPase activities were estimated. ATPase activity was inhibited in the gill tissue of oysters ( p < 0.05) of PJ sample. Total microbial load in the water and oyster, and coliform bacteria (MPN) in the water were significantly ( p < 0.05) higher at PJ compared to the NW. There was no significant difference ( p > 0.05) in the mineral profile of water collected from both the sites. However, calcium and magnesium were more in the oysters collected from NW ( p < 0.05), and Cu, Zn and Cd were more in PJ samples ( p < 0.05). [ABSTRACT FROM AUTHOR]

A two-dimensional hydrodynamic and particle tracking model was used to estimate the dispersion and retention of barnacle larvae from their possible spawning sites in a tropical monsoon-influenced estuarine system (central west coast of India). Validation of the hydrodynamic simulations yielded a good match with field measurements. The pattern of larval dispersal in the region varied with the winds and currents. The seasonal changes in abundance could be attributed to physical forcing and weather conditions. The extent of barnacle larval dispersal from spawning sites varied from 10 to 78 km for different sites and seasons. During a 24-h cycle, the larval abundance showed one to two peaks in the estuarine area. The increased larval abundance is favored by the flood currents, pushing the larvae into the estuary. Physical forcing in the region helps in transport of the larvae from their spawning sites hugging to the coast and contributing to the population within the estuary. Field observations and numerical experiments suggest the occurrence of higher larval abundance in the estuary during post-monsoon. The dispersal pattern indicated that the barnacle population present in the estuary is well mixed, and with a seasonally changing pattern. [ABSTRACT FROM AUTHOR]

Abstract: This study combines observational data with a two-dimensional numerical model results to determine the fate of fish eggs released in the Gulf of Kachchh (GoK), a semi enclosed basin on the west coast of India. Fish eggs were treated as passive particles in the model, and were released from probable spawning sites identified from the field surveys. Areas with retention of larvae above 30% have been demarcated as nursery areas. Most of these nursery areas fall in ecologically significant sites which are rich in mangroves and reefs. We find that about 80% of the particles are retained in the basin for all the three prominent seasons prevailing in the GoK. Complete retention of particles in the southern Gulf region and small quantity of flushing out in the northern boundary of the Gulf could be a major reason for sustaining an abundance of larvae in the southern Gulf. Trawler catch data at various sampling points also suggest abundance of fish in the southern GoK region. Model simulation of fish larval transport in the GoK reiterates the fact that fish larval aggregation occurs in the southern GoK during active breeding phase with varying dispersal patterns from spawning sites. Marine protected areas in the Gulf demarcated based on the ecological significance of sites reasonably corroborate with the areas of likelihood of retention of fish larvae differentiated by the model. [Copyright &y& Elsevier]