Abundance, characteristics and variation of microplastics in different freshwater fish species from Bangladesh

Abstract

Microplastic (MP) contamination in fish species is one of the emerging environmental problems due to the proliferation of plastic pollution in the environment. The occurrence of MPs in the freshwater of Bangladesh is currently unreported, and in contrast to other counties of the world, little is known about the occurrence of this contaminant in freshwater fishes. Hence, this study investigated the abundance, characteristics, and variation of MPs in different commercial freshwater fish species from Bangladesh. This country generates a considerable amount of plastic waste annually, and a significant portion of its remains uncollected. Forty eight fishes from eighteen taxa spanning different feeding zones were collected to observe the difference in MPs ingestion rate among various feeding zones. MPs were found in the gastrointestinal tracts (GIT) of 73.3% of all examined fish samples, which is relatively higher than previously reported studies in other regions. The abundance of MPs was found highest in Mystus vittatus among all of the fish species. Microscopic analyses (polarized light, SEM) revealed that MPs were dominated by fiber in shape and transparent in color. Fourier Transform Infrared analysis (FTIR) showed that polymers found in fish GIT were high density polyethylene, polypropylene-polyethylene copolymer and ethylene vinyl acetate. The results of this study show that demersal fishes presented a higher amount of MPs than registered in benthopelagic and pelagic fishes, indicating the ingestion of plastics in fish may relate to the feeding habitat. However, differences in body weight and length of the fishes were not found to influence the MPs ingestion. Our findings will help to aware people which freshwater fishes and fishes from which feeding zone are more contaminated with MPs to human consumption in Bangladesh.