Productive zone mapping of the Swandip Coast, Bay of Bengal: A geospatial analysis to suggest potential mariculture hotspots

Abstract

Bangladesh has abundant marine resources in the Bay of Bengal but lacks comprehensive evaluations of hydrology and
productivity. Geospatial technologies can direct sustainable management of marine resources and find productive hotspots. In
order to suggest possible mariculture locations, this study concentrated on locating productive zones within a 7 km buffer
surrounding Swandip Island of the Bay of Bengal. Three important hydrological indices were mapped using ArcGIS
analysis of Landsat-8 data from July 2023 to July 2024: sea surface temperature (°C), turbidity (Nephelometric turbidity
unit), and Ch-a concentration (mg/m³). The data underwent atmospheric and radiometric corrections before overlay analysis.
The sea surface temperature ranged from 19.83 to 33.64°C. Findings showed that 50–60% of the eastern and northeastern
sections had colder waters (19–24°C) and 30–40% had moderate temperatures (25–30°C). The concentrations of chlorophyll-a
varied from 0.2 to 0.48 mg/m³, with the north and southwest having the highest concentration. Turbidity ranged from 0.0446
to 0.0808 NTU (Nephelometric Turbidity Unit). In 60–70% of the northern, western, and southwestern regions, there was
considerable turbidity (0.070–0.0808 NTU). The productive zones were predominant from northwestern, western to
southwestern regions and suggested for mariculture pursuits such as shellfish culture, cage culture of fish, and seaweed culture. The
Bay of Bengal's sustainable economic exploitation of marine resources can be optimized with the help of these insightful
findings and insights. The study recommends geospatial analysis and marine spatial planning of more marine productive areas.