Influence of Microplastics on Freshwater Bivalves (Review)

Anthropogenic pollution of the aquatic environment with microplastics is one of the most urgent but least studied problems of modern ecotoxicology. This review, based on recent literature data, provides an analysis of studies in the field of absorption, bioaccumulation, and biological effects of microplastic exposure in freshwater bivalve mollusks (Bivalvia). A total of 22 studies have been conducted so far, which were performed on representatives of three families: Cyrenidae (45), Unionidae (25), and Dreissenidae (30%). The studies are made up of field observations (43.5) and field (8.7) and laboratory (47.8%) experiments. It has been shown that freshwater bivalves, as active filters, are able to absorb and accumulate in soft tissues (gills and hepatopancreas) microplastic particles from both water and bottom sediments, perceiving them as food objects. The bioaccumulation of microplastics in mollusks leads to functional and structural disorders in the body. The joint action of microplastics and other pollutants (cadmium, polychlorinated biphenyls, and pharmacological drugs) can cause both synergistic and antagonistic effects in the biological responses of mollusks. Based on these studies, it is suggested to use bivalve mollusks as bioindicators of freshwater pollution with microplastics.