Журнал наук о Земле и изменения климата

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Utilization of Carbon in NPZ Model of Hooghly Estuarine System, India

Joyita M, Debaldeb J, Moitreyee B, Phani Bhusan G, Santanu R

Hooghly estuary along with the luxurious mangroves of the Sundarbans is one of the important estuaries of India. A quite rich mangrove patch in association with the creeks is visible at Sagar Island, the largest island in the row. Degradation and leaching of litter provides nutrient for the growth and development of phytoplankton which in turn strengthens the grazing food chain from zooplankton to fish. Phytoplankton growth is influenced by solar radiation, nutrient and temperature. The model incorporates light acclimation by algae, self-shading, photosynthetic production and nutrient uptake. Water quality changes with seasons. The model uses the functional relations among the three state variables as observed in response to the changeable environment throughout the year there. The model is calibrated and validated taking carbon as the currency of the model. Dissolved inorganic carbon as nutrient, water temperature, surface solar irradiance, and salinity of upstream and downstream of the estuary are collected from the field. Model results indicate that the growth of zooplankton and phytoplankton are enhanced by increasing nutrient input in the system. The predicted temporal distribution and trends of plankton biomass, inorganic carbon is in general agreement with field observations. Sensitivity analysis has been done. The model captures the dynamics of plankton population, which serve as major food source for fish species of the estuary. This model could be predictive in search for the role of mangrove in estuary and its control on nutrient and plankton dynamics of this region which will be helpful in management aspect.