Assessing the ecological preferences of planktic foraminifera from the south-eastern Arabian Sea

The south-eastern Arabian Sea (SEAS) witnesses the confluence of the Arabian Sea and the Bay of Bengal waters along with an influence from both the summer and winter monsoon. As a result, the distinct hydrographic parameters are expected to modulate the diversity and abundance of planktic foraminifera in this region. Hence, 91 surface sediment samples covering a depth range from 25 m to 3150 m were analysed to establish region-specific planktic foraminiferal ecology. Overall, the water depth, seasonal chlorophyll-a and the mixed layer parameters significantly influence the planktic foraminiferal abundance in the SEAS. A total of 31 species of planktic foraminifera belonging to 17 genera were found. We report Globigerina bulloides as the most dominant species, preferring high productivity regions. Globigerina bulloides and Globigerinoides ruber exhibited opportunistic distribution patterns while region-specific preferences were observed for Globigerinita glutinata, N. dutertrei, Globorotalia cultrata and Trilobatus sacculifer. Globigerinita glutinata show a restricted seasonal occurrence while G. hexagonus is reported as a ubiquitous species. The ecological preferences of the planktic foraminifera inferred from the SEAS will help in reconstructing the past climatic conditions from this region.