Modelling of Plankton and Forage Fish Variability in the Gulf of Kachchh Using 2D Coupled Physico-Biological Model

A biophysical coupled model, which includes interaction of processes at different spatial and temporal scales, is used to assess the seasonal variability of plankton and forage fish. A five-compartment nutrient, phytoplankton, zooplankton, detritus, forage(NPZDF) ecological model is coupled with hydrodynamic model to understand the interaction of hydrographic characteristics and ecological dynamics in the study area. Operator splitting method is used to handle two different physical and biological scales for numerical simulation of the resulting partial differential equations. Gulf of Kachchh (22°20'N–23°40'N, 68°20'E–70°40'E), in the northwest coast of India is used for the application and validation of the model’s behaviour. This region demonstrates rich biodiversity and productivity in highly turbid and varying marine conditions. Co-ordinate transformation is used to convert the irregular coastal geometry of Gulf of Kachchh into a rectangular domain. Numerical experiments, together with sensitivity analysis are carried out to get the values/ranges of the model parameters. The model application is able to bring out many striking features of the Gulf of Kachchh including bimodal oscillations observed in the ecological data of the region.