Ecosystem structure and trophic dynamics of an exploited ecosystem of Bay of Bengal, Sundarban Estuary, India

Abstract

A trophic structure model for commercial fisheries of Sundarban Estuary in the northern Bay of Bengal (BoB) is developed using the mass balance modeling software Ecopath (Version 6.4.10992.0). In this model, we simulated 15 functional groups spread across an area of 17,049 km2. The mean trophic level of the present study area is 2.716. The ecotrophic efficiency of the present studied ecosystem is in the range of 0.424 of medium demersals and 0.961 of medium pelagics. Penaeid prawn, small pelagics, and medium pelagics are the most exploited groups of this ecosystem. The coastal northern BoB food web is mainly detritivorous and planktivorous; phytoplankton and detritus positively affected almost all the functional groups, and top predators are essentially absent in the system. The zooplankton and benthos have negative impacts on themselves because of cannibalistic behavior. The average catch per net primary production, i.e. the gross efficiency of the system is around 0.001. The system is low trophic and efficient. Proper ecosystem-based management practice can improve the efficiency of this overexploited ecosystem.