Environmental consequences of coastal aquaculture in Bangladesh: insights from water, sediment, and biodiversity monitoring

Coastal aquaculture plays an important role in supporting food production and sustaining livelihoods in Bangladesh. However, its rapid growth in recent years has also raised questions about potential environmental impacts. This study examined differences between aquaculture site (AS) and nearby non-aquaculture site (NAS) locations across 5 coastal districts to better understand how aquaculture activities influence water quality, sediment conditions, and biodiversity. Fifty sites were surveyed between November 2024 and January 2025, and samples were analyzed for nutrient levels, heavy metals, pesticide residues, and ecological indicators. The findings showed that ASs generally had higher levels of dissolved inorganic nitrogen and phosphorus, elevated chl a concentrations, and increased amounts of heavy metals such as Cd, Pb, and Cr. In contrast, NASs supported a greater variety of species and exhibited higher Shannon diversity indices. Multivariate analyses further indicated that aquaculture practices are closely associated with nutrient loading, accumulation of contaminants, and shifts in community structure. The study highlights the importance of adopting more sustainable management strategies, including better waste handling, the promotion of integrated multi-trophic aquaculture, and stronger regulatory oversight, to help protect the health of coastal ecosystems in Bangladesh while maintaining the benefits of aquaculture.