Influence of river discharge on abundance and composition of phytoplankton in the western coastal Bay of Bengal during peak discharge period

To understand the influence of river discharge on phytoplankton composition along western coastal Bay of Bengal (BoB), surface water samples were collected during peak discharge period. River discharge from the Ganges influences northwest (NW) coastal BoB whereas peninsular rivers (Godavari and Krishna) discharge to the southwest (SW) coastal Bay. River discharge from the Ganges is an order of magnitude higher than peninsular river resulting in low saline, less suspended matter and lower nutrients concentrations in the NW and contrasting to that was observed in the SW. ~50%of the phytoplankton were composed of Thalassiosira spp., Nitzschia spp., Microcystis spp., Amphiprora spp. and Thalassionema spp. in the SW whereas Thalassiosira spp., Nitzschia spp., Chaetoceros spp., Merismopedia spp. and Peridinium spp. in the NW. Significant variability in phytoplankton composition was observed from coast to offshore. Our study revealed that river discharge and associated physico-chemical characteristics governed the phytoplankton community along western coastal BoB.