Seasonal variation in the flux of planktic foraminifera: Sediment trap results from the Bay of Bengal, northern Indian ocean

Particulate flux from two sediment trap mooring stations in the central and northern Bay of Bengal were analyzed for planktic foraminiferal abundance, In the sediment trap samples, 26 species are present, of which eight accounted for over 90% of the total planktic foraminiferal flux. The total particulate flux of <1 mm size is the largest component in the sediment trap samples and generally showed an increase with depth in the water column, Total particulate flux and planktic foraminiferal flux exhibited similar, hi-modal distribution patterns related to the monsoons, The highest fluxes are recorded during the southwest monsoon; fluxes during the northeast monsoon are elevated but not to the level seen during the southwest monsoon, with Globigerina bulloides dominating the foraminiferal flux. The overwhelming proportion of G. bulloides in the foraminiferal assemblage is suggestive of upwelling activity occurring in the western Bay of Bengal region during the southwest monsoon, The reduced productivity of foraminiferal species in northern Bay of Bengal is related to the injection of fresh water as a result of increased precipitation associated with the southwest monsoon. Four species (Neogloboquadrina dutertrei, Globigerina aequilateralis, Globigerinita glutinata, and Globigerina rubescens) exhibit elevated fluxes in the lower salinity region, Foraminiferal productivity in the Bay of Bengal is one order of magnitude lower than that in the Arabian Sea.