Tracking the microplastic pollution in the freshwater environments of southeastern Türkiye: Usage of Unio delicatus, Unio Terminalis and Dreissena polymorpha as bioindicators of microplastics

Microplastic (MP) pollution levels in aquatic environments raise concerns regarding the potential harm to biota and the environment. Mussel species are categorized as perfect bioindicator of pollutants due to their sessile lifestyle, and filter-feeding activity that also make them more prone to microplastic contamination. This study was designed to assess microplastic pollution levels in the soft tissues of dominant freshwater mussel species to understand general picture in microplastic contamination of the ambient environment. For that purpose, microplastic presence in the soft tissue of Unio delicatus (n:49), Unio Terminalis (n:31) and Dreissena polymorpha (n:82) was investigated. Including all examined specimens, mean microplastic abundance was found as 0.6 ± 0.8 items/ind, 0.2 ± 0.5 items/g ww with occurrence rate of 48 %. Reflecting global distribution, general morphological characteristics of MPs were fiber shape, blue colored and less than 500 μm in size. Fourier transform infrared (FTIR) spectroscopy identified the polymer type of MPs as polyethylene (40 %), polypropylene (47 %), and polystyrene (27 %). The results obtained in this study provide baseline information regarding microplastic contamination in freshwater environments and emphasize the need of protective measures.