RECENT OSTRACOD BIODIVERSITY FROM SHELF TO SLOPE SEDIMENTS OF GULF OF MANNAR, INDIA: ECOLOGIC AND BATHYMETRIC IMPLICATIONS

The present study has been focused to create the baseline data for the distribution and biodiversity of Ostracoda from the continental shelf to slope sediments of Gulf of Mannar. For the purpose, 5 short core samples were collected through multi-corer, ranged in water depth from 58 m to 1887 m (shallow to deep-marine water) during Cruise SSD-004 (ORV Sindhu Sadhana). A total of 4355 ostracod specimens were recovered, belonging to 82 species and 51 genera. Of these, 14 species were recorded for the first time from the Indian waters. Bathymetric distribution of Ostracoda in all the five multi-core samples are studied, in which Propontocypris bengalensis, a species that is dominantly present in shallow water region (MC-8). Species of Krithe recorded only in deeper water regions (MC-2 and MC-60). Xestoleberis sp. and Paracypris sp. are the only species which were present from the continental shelf to slope sediments of Gulf of Mannar. The faunal carapaces are fresh, shiny, and not pyritised. The ornamentation on the carapaces changes gradually in accordance with the sediments that grades from coarse to fine towards the deeper water and the population of ostracod also varies from shallow to deeper water sediments. Core-wise distributions of ostracods species, ecological implications and species diversity have also been discussed.