Bathymetric preference of four major genera of rectilinear benthic foraminifera within oxygen minimum zone in Arabian Sea off central west coast of India

摘要

Fifty two surface sediment samples collected from the region off Goa, central west coast of India from water depths of 15a€“3300 m were analyzed with special emphasis on foraminiferal content. Rectilinear benthic foraminiferal morphogroup shows a high relative abundance within Oxygen Minimum Zone (OMZ), both shallow marine (50a€“60 m water depth) and intermediate to deep water (150a€“1500 m water depth). We gave special emphasis on four rectilinear foraminiferal genera, namely Fursenkoina, Bolivina, Bulimina and Uvigerina to observe their individual distribution among OMZ. We found genus Fursenkoina predominates at the shallow water OMZ, within the water depth zone of 50a€“60 m. Within 150a€“1500 m water depth, which is considered as intermediate to deep water OMZ in this region, genus Uvigerina shows its highest abundance above 1000 m water depth, whereas genus Bulimina shows its affinity with deeper water environment ( 1000 m water depth). Genus Bolivina does not show any such depth preference, except its higher abundance in only intermediate to deep water OMZ. This depth differentiation among four rectilinear benthic foraminiferal genera presents the basic data for palaeoclimatic study based on the extent and intensity of OMZ along with the palaeobathymetry study.