A geospatial assessment of growth pattern of aquaculture in the Indian Sundarbans Biosphere Reserve

Indian Sundarbans Biosphere Reserve (SBR) comprising over 100 estuarine islands and shared by human habitation and mangrove forests is considered to be a potential area for coastal aquaculture. This study, using LANDSAT imageries of the last two decades (1999–2019), delineated the spatiotemporal expansion of aquaculture at the expense of agricultural land, mudflats, and some mangroves. It also estimated a futuristic land transformation to aquaculture using the Cellular Automata-Markov Chain model. From the geospatial analysis, it is observed that (1) the aquacultures are mostly located around 22° 30′N, i.e., far away from the saline seafront, (2) total aquaculture area has increased to nearly 5.82% of the entire SBR in 2019 from 3.59% in 1999 and, (3) cyclone Aila and its surge inundation have influenced in their expansion. This growth of aquaculture took place with the loss of 3.71% (10,536.67 ha) agricultural land, 3.87% (730.40 ha) mudflat, and 0.28% (623.23 ha) mangrove from 1999 to 2009, and 6.02% (13,471.50 ha) agricultural land, 9.98% (1583.64 ha) mudflat, and 0.18% (382.35 ha) mangrove during 2009–2019. According to the predictive modeling, ~ 6% of the present agriculture area is prognosticated to be converted to aquaculture by the next decade under a business-as-usual scenario.