Distribution of benthic foraminifera within oxygen minima zone, off central west coast, India

A total of 128 surface sediment samples [76 grab and 52 core top samples] were analyzed for benthic foraminiferal contents from the region off Goa in the eastern Arabian Sea upto a water depth of 3300 m. 195 species of benthic foraminifera were identified. Species belonging to Bolivina, Cassidulina, Lernella, Uvigerina and Eponides were found to be the most abundant within the depth zone of 150 to 1500 m a zone considered to be Oxygen Minima Zone (OMZ) for Arabian Sea. Comparison of benthic foraminiferal species abundance in OMZ of Arabian Sea with other parts of the world oceans reveals some interesting facts. Bulimina marginata, which has been reported to be present in considerable number within the OMZ in other regions of the world oceans, accounted for only about 2% of the total benthic foraminifera population in the present area. On the contrary, Bulimina costata constituted more than 15% of the total foraminifera, which has not been reported to be abundant from OMZ of any other region of the world. This study confirms the presence of characteristic nature of the oxygen minima zone in the eastern Arabian Sea.