Summary of Abstract Submission

Abstract Submission No. IO50-09-0067PresentationPoster

BENTHIC EPIFAUNAL COMMUNTIES FEATURING THE OMZ OFF NORTH EAST INDIAN COAST, BAY OF BENGAL

Akkur v Raman*1, Thiruchitrambalam Ganesh1, Y.K.V. Rao1, Sateesh Nanduri1, Rakhesh Madhusoodhanan1

1 Andhra University, India

ABSTRACT :

Samples of epibenthic macrofauna were collected using a naturalist¿s dredge from 63 locations off the north East Indian coast that represented a gradient of depths - shallow water (10-30 m), continental shelf (50-200 m) and the upper slope (200-500 m) featuring the oxygen minimum zone (OMZ). Altogether 251 taxa were collected, predominantly molluscs, crustaceans, polychaetes and echinoderms together accounting for over 85% of total numbers. Multivariate procedures powered by SIMPROF analysis on benthos abundance data revealed discrete groups of epibenthic communities that characterised the shallowest inshore locations (mean depth 22m), upper shelf (43m), mid shelf (65m), outer shelf (106m) and the upper slope (230m) showing significant disparities (ANOSIM Global R=0.785; P=0.1%). While the shallowest locations (22m) supported a rich population of cnidarians (Sphenopus arenaceus) and the brachyuran Charybdis sp., it was a combination of Charybdis sp. and eunicid polychaete Diopatra neapolitana at the upper shelf (44m). In the mid shelf (65m), the turrid gastropod Lophiotoma indica, together with decapods Raninoides serratifrons and Liagore sp. made up the bulk. At the lower shelf (130 m), there were overwhelming numbers of eunicids and Polychelid lobsters. At the upper slope (230m), bivalves Amygdalum watsonii and Nucula consentenea dominated along with Oplophorids (deep-sea shrimps), the spider crab Pyromaia tuberculata and the stylaroid worm Stylaroides bengalensis characteristic of deep-water regions. The paper purports to demonstrate the influence of key environmental factors that shaped the above communities in terms of their distribution and diversity particularly the OMZ effects characteristic of these waters in Bay of Bengal.