Simulation of plankton dynamics in the Hooghly Estuary using a high resolution biophysical model

A first attempt is made towards the coupling of a three-dimensional circulation model with a four compartment bio-physical model to simulate the regional distribution of plankton biomass and productivity in the Hooghly Estuary (approximately 21°36´-22°16´N and 87°42´-88°15´E) and to gain insights into the key physical and biological processes that control the plankton dynamics in the Estuary. In-situ observational data for physical and biological parameters were collected from Calcutta University during 2010 are assimilated using multiscale objective analysis (OA) and incorporated in Regional Ocean Modeling System (ROMS) to develop a four-compartment (Nutrient (N), Phytoplankton (P), Zooplankton (Z) and Detritus (D)) bio-physical model. The sensitivity of chlorophyll a (chl-a) biomass on the changing effect of salinity is dominating and a drastic decrease in chl_a (less than 2 mg/m³) has been observed in Haldia Station where the influence of high nitrate (above 32 ug/l) is predominant and thus effects water quality.