Microplastics in commercial fish and their habitats in the important fishing ground of the Black Sea: Characteristic, concentration, and risk assessment

Microplastics in commercial fish species from both pelagic and benthic environments were analysed, along with their distribution in the southeastern Black Sea's surface, water column, and sediments. A total of 659 fish from 6 species (Trachurus mediterraneus, Merlangius merlangus, Mullus barbatus, Scophthalmus maximus, Platichthys flesus, Pegusa lascaris) were collected from 4 stations between March and July 2022. Microplastics were characterized using optical microscopy and FT-IR analysis. Mean microplastic concentration was 77 ± 11 mp.m^-3 in surface waters, 189 ± 108 mp.m^-3 in water column, 24 ± 30 mp.kg^-1 in sediments and 0.91 ± 0.96 mp.ind^-1 for all fish analysed. Fibers were the dominant type across all environmental matrices including fish. Polyethylene terephthalate was the most common polymer in surface waters and water column, polypropylene and polyethylene were more prevalent in sediment, while polyethylene terephthalate and polyacrylonitrile were the most common polymer found in fish gastrointestinal tracks. Microplastic ingestion was statistically higher in demersal fish compared to pelagic and benthopelagic species. Estimated Microplastic Pollution Load Index value showed that all fish analysed were significantly contaminated by microplastics. Polymer Hazard Index was calculated as 2944 with a hazard level "V" which has a very high risk. This study highlights the significant threat microplastic contamination poses to the Black Sea ecosystem and human health, stressing the need for further research on its extent and associated risks.