Diversity and distribution of echinoderms in the South Eastern Arabian Sea shelf under the influence of seasonal hypoxia

摘要: Abstract The South Eastern Arabian Sea (SEAS) margin represents a tropical eastern boundary upwelling system, which is subjected to intense seasonal hypoxia in the continental shelf, and impingement of oxygen minimum zone (OMZ) along slope. This paper provides first comprehensive information on abundance, diversity distribution patterns echinoderms, are highly sensitive deficiency anthropogenic disturbances, shelf (∼20–250 m) SEAS. Results based depth stratified seasonally resolved sampling at 241 sites, representing 8 latitudinal grids & 4 strata (from inner edge) using naturalist dredge Smith-McIntyre grab. Echinoderms were numerically dominant group among epifauna (42%), with significant variations relative abundance (71% during winter 17% summer monsoon). Fifty-five species echinoderms identified, ophiuroids showed highest (24 species) followed by echinoids (11 asteroids (8 species). Species richness was higher mid (20–80 m), while nearly absent edge (150–250 m). A negative correlation noted between latitude, three distinct sub-regions could be delineated abundance. observed found determined chiefly sediment texture bottom water dissolved oxygen, disturbances (bottom trawling). maximum well-oxygenated sandy sediments southern SEAS, very low relatively silty northern characterised high fluctuations (seasonal hypoxia). near absence despite availability substrates indicates that this more perennially conditions prevailing here.