Summary of Abstract Submission

Abstract Submission No. IO50-09-0049PresentationPoster

MEGABENTHIC COMMUNITY STRUCTURE FROM TWO DIFFERENT ECOSYSTEMS (SEAMOUNTS AND MID OCEANIC RIDGE) IN DEEP INDIAN OCEAN

Sabyasachi Sautya*1

1 Regeional Centre, Mumbai, CSIR-National Institute of Oceanography, India

ABSTRACT :

There are few quantitative studies on deep-sea biodiversity from the Indian Ocean, particularly on the seamounts and mid oceanic ridge (MOR) areas. Occurrences of deep-water megafaunal community on the Carlsberg Ridge (CR) and Andaman Back-arc Basin (ABB) along with two seamounts (CSM and SM2) have been examined based on underwater video and photographic surveys and by catch. Our aim was to explore and generate regional benthic biodiversity data from seamounts and MOR in Indian Ocean for comparison with other oceans. We found 13 varieties of substratum and total of 948 individuals from 58 taxa, representing eight phyla in ABB region including seamounts. The cratered seamount (CSM) has hard substratum, whereas the SM2 seamount was dominated by cobbles and fine sediment. The highest abundance and megabenthic diversity and species richness were observed along the flank of the CSM followed by SM2 flank. New species of hexactinellid sponge, brittle stars and new records of brittle stars and an epibiont associated with nematode have been reported from the CSM seamount. A total of 8 substratum types and 90 megafaunal taxa, representing 7 phyla, were identified have been classified throughout the eleven transects located in CR. Faunal abundances ranged between 171.3 to 5.7 animals/1000 m2, with higher abundances at the shallower transect in off axial highs and lower at deeper zones in rift valley wall and floor. Cnidarians were dominant at off axial highs, while echinoderms prevailed at rift valley floor transects. One new genus of glass sponge has been discovered from CR region.