Microplastic Pollution in Indigenous Fish From the Padma River, Bangladesh: A Case Study

Abstract

Microplastics (MPs) are prevalent in aquatic ecosystems; however, inland water bodies have received relatively little attention. These ecosystems provide essential habitat for various fish species, which contribute to ecological equilibrium and support the livelihoods and food security of millions. Fish demonstrate increased vulnerability to microplastic ingestion, making them essential bioindicators of ecosystem health and contamination levels. This study evaluates the presence of MPs in the intestine, gills, and muscle tissue of 30 individuals belonging to five commonly found fish species (Rhinomugil corsula, Mystus tengara, Ompok pabda, Labeo bata, and Cirrhinus mrigala) in the Padma River. A total of 252 MP items of different shapes were recorded in 100% of individuals investigated, exhibiting an average frequency of 8.27 ± 2.16 items per individual. Among the fish species, Ompok pabda exhibited the highest ingestion of MPs, with an average of 11.5 ± 1.87 items per individual, followed by other species. Organ-wise analysis of MPs trend was found to be: intestine > gill > muscle. Fiber was recognized as the most commonly consumed MP type (72%), followed by fragment (22%), pellet (4%), and foam (2%). The white-color MP (24%) was predominant, followed by other colored MPs. The majority of MP particles were found in the size class 1–5 mm (41.10% ± 12.34%), followed by <500 μm (34.18% ± 16.34%) and 500 μm–1 mm (24.72% ± 11.51%). Fourier transform infrared (FT-IR) spectroscopy investigation confirms both high- and low-density polyethylene polymeric compositions of MPs. The study assesses the prevalence of microplastics in Padma River fish, highlighting the immediate necessity for focused conservation initiatives, ongoing monitoring, and evaluation of microplastic pollution to protect aquatic ecosystems and human health.