Microplastics in pelagic and demersal fishes from the Meghna River estuary, Bangladesh

Microplastics (MPs) were investigated in four fish species viz., paradise threadfin (Polynemus paradiseus), corsula mullet (Rhinomugil corsula), flathead sillago (Sillaginopsis panijus) and king gobyeel (Taenioides sandwipi), which were collected from the Meghna River estuary in Bangladesh. The gastrointestinal tracts (GITs) of fishes (n = 80 in total) were examined for the presence of MPs following alkali digestion, microscopic observation and μ-FTIR analysis. A total of 573 MPs were detected across all four fish species, indicating the presence of MPs in 81.3% of the fish samples. On average, there were 7.16 ± 4.33 MP items/fish, 2.16 ± 1.76 items/g of GIT and 0.15 ± 0.12 items/g of body weight. Polyethylene, polypropylene and nylon were the most abundant polymers, comprising 47%, 23% and 19%, respectively, according to μ-FTIR analysis. The majority of MPs were fibers (62.48%), with white being the dominant color. R. corsula demonstrated the highest number of MPs in the < 500 μm size range, suggesting that smaller particles are more bio-available to pelagic fish. The findings confirm the contamination of the Meghna River estuary by MPs, and their presence in local fish raises concerns about potential public health risks through the food chain.