Microplastics accumulation in sediments and Periophthalmus waltoni fish, mangrove forests in southern Iran.

This investigation was aimed to identify microplastics in the sediment and mudskipper fish (Periophthalmus waltoni) in mangrove forests in southern Iran. Sediments and mudskipper samples were collected at high, mid, and low tidal points of five stations. A total of 2657 plastic particles in different size, color, shape, and genera were identified from sediment samples and 15 microplastic were isolated from mudskippers. The highest and lowest abundance of isolated microplastics from sediments was observed in mangrove forests of Bidkhoun (urban area) and Bordkhon, respectively while no microplastics were found in the fish tissue in those stations. The black (60%) and white (7%) color microplastics in the mudskipper had the highest and the lowest frequency. The highest and lowest polymers in mangrove forest sediments were corresponded to polystyrene (26%) and polycarbonate (3%), respectively. Raman and Fourier transform infrared spectroscopy (FT-IR) techniques were used to identify the type of the polymer. Most of the microplastics found were made of polystyrene, polypropylene, and polyethylene terephthalate. The type of studied area and texture of sediment separately affected the frequency of microplastic and mesoplastic (P-value <0.05) in the sediment samples. The abundance of microplastics in the sediment samples of the Bidkhoun mangrove forest was higher than other studied stations due to proximity to urban and industrial areas. The findings of this study raised concerns about microplastic pollution in the mangrove forests of southern Iran, a threat to the ecosystem and public health, which requires careful actions to prevent and diminish its adverse effects.