No abstract

The adaptive genetic variation in response to heterogeneous habitats of the Indian Ocean was investigated in the Indian oil sardine using ddRAD sequencing to understand the subpopulation structure, stock complexity, mechanisms of resilience, and vulnerability in the face of climate change. Samples were collected from different ecoregions of the Indian ocean and ddRAD sequencing was carried out. Population genetic analyses revealed that samples from the Gulf of Oman significantly diverged from other Indian Ocean samples. SNP allele-environment correlation revealed the presence of candidate loci correlated with the environmental variables like annual sea surface temperature, chlorophyll-a, and dissolved oxygen concentration which might represent genomic regions allegedly diverging as a result of local adaptation. Larval dispersal modelling along the southwest coast of India indicated a high dispersal rate. The two major subpopulations (Gulf of Oman and Indian) need to be managed regionally to ensure the preservation of genetic diversity, which is crucial for climatic resilience.

Gulf of Mannar Ecosystem (GOME) covers an area spread over Rameswaram and Kanyakumari for about 19000 km 2 and lies between 78°11'E and 79°15' E longitude and 8°49'N and 9°15'N latitude. The 21 coral islands form a network of habitats for different kinds of fishes and marine organisms.

Polka-dot ribbonfish Desmodema polystictum was recorded for the first time from Indian waters. A single specimen of D. polystictum (107 cm total length and weighing 480 g) was collected from Tharuvaikulam landing centre, north to Tuticorin, on the south-east coast of India during September 2010. The distinguishing characters of the species from other species of the family are discussed. Morphometric and meristic characters of D. polystictum are presented in this paper. With the present report, the distribution area of this species now extends to the Indian waters.

The dynamics of fauna in coastal ecosystems are influenced by seasonal patterns in the oceanographic environment. It is well known that the monsoon along south-west coast of India influences the movement and spawning of fishes. Thus, they have direct effect on the richness, abundance and evenness of fish diversity in the ecosystem. This study investigates how the monsoon affects the commercial gillnet fishery along the coast of Goa. Fishing experiments were conducted in popular gillnet fishing grounds and the temporal pattern in diversity indices between October 2013 and September 2014 was assessed. A total of 124 fish species (40 families), 16 crustacean species (4 families) and 9 molluscan species (8 families) were recorded. The species diversity was found to be significantly different during the monsoon season and the species abundance distribution followed a geometric series during this period indicating signs of ecosystem perturbations. The economic and biological aspects of gillnet fishing in relation to the monsoon season in Goa are also discussed.