Microplastic fibers in the gut of highly consumed fish species from the southern Caspian Sea

This study assesses the frequency, distribution, characteristics, and chemical composition of microplastics (MPs) in the gut of highly consumed fish species, namely leaping mullet (Chelon saliens), common carp (Cyprinus carpioi), and Caspian kutum (Rutilus caspicus), in the southern Caspian Sea biome. Fibers are found to be the only shape of MPs. Black MPs and polystyrene, polypropylene, and polyethylene terephthalate polymers are dominant. MP frequency is highest in leaping mullet's gut, while kutum specimens exhibited the lowest MP frequency, reflecting that leaping mullet is a neritic species and thus highly exposed to MP influx in shallow coastal water, while the other species are benthopelagic. The estimated condition index reflected a significant difference between the species, implying that MPs may pose adverse health impacts on leaping mullet and common carp, with no undesirable effect on Caspian kutum. No significant relationship exists between biological parameters and the MP frequency in the fish gut.

Automated summary

The study found that leaping mullet had the highest frequency of microplastics (MPs) in their gut in the southern Caspian Sea biome, while Caspian kutum had the lowest. MPs were mainly in fiber shape, and the dominant polymers were black MPs, polystyrene, polypropylene, and polyethylene terephthalate. Different fish species showed significant differences in condition index, suggesting that MPs may have adverse health impacts on leaping mullet and common carp, but not on Caspian kutum.