The first evidence of microplastic uptake in natural freshwater mussel, Unio stevenianus from Karasu River, Turkey.

ABSTRACT

PURPOSE: Microplastic pollution is a major problem that threatens freshwater mussels as well as marine bivalves, since these filter-feeding organisms are directly exposed to microplastics in the water column. There is no study on the microplastic contamination of Unio stevenianus as a bioindicator organism. The aim of this study is to determine the microplastic contamination in U. stevenianus. MATERIALS AND METHODS: In total, 32 U. stevenianus were obtained from three different sites from Karasu River, in October 2020. The soft tissue of each mussel was digested and filtered. The filters with microplastics were observed under a stereomicroscope. RESULTS: A total of 1,253 microplastics, ranging from 0.81 to 6.69 items/gram (mean 2.85 ± 1.27 items/g) and 13.00 to 84.73 items/individual (mean 39.15 ± 16.95 items/individual), were extracted from soft tissues of mussel for all stations. The dominant of the detected microplastics consisted of fragment (48.8%) followed by fiber (47.5%) types, and ˂0.1 mm size (44.8%), irregular shape (48.7%) and black coloured (48.8%) items were the most uptaked microplastics. CONCLUSION: This study indicated that U. stevenianus has a lot of pollution where there are a lot of microplastics in the river.