Аннотация:Recent results suggest that bivalves can serve as an important natural barrier restraining spread of various aquatic infections. However the ability of mussels to eliminate free-living stages of macroparasites and reduce their transmission is still understudied, especially for freshwater ecosystems. We experimentally investigated the influence of the common freshwater mussel (Anodonta anatina) on the transmission of the trematode (eye fluke Diplostomum pseudospathaceum), which frequently infects fish in farms and natural habitats. Our experiments indicate that mussels caused a significant decrease (P < 0.001) in the abundance of trematode free-living stages (about 4-fold in 2 hours), reducing it from 6520 to 1770 cercariae L-1 on average. Individual clearance rates of mussels constituted 0.6‒3.7 L per hour (mean 1.9). These tests were followed by the experimental infections of fish (Oncorhynchus mykiss) with different doses of D. pseudospathaceum cercariae in the presence or absence of mussels in the environment. Exposure of fish to cercariae in the presence of mussels significantly reduced the infection intensities in fish (by 30-40%) at all exposure doses (P < 0.05). Our results indicate that bivalves can remarkably reduce local cercariae densities and could be useful in mitigation of trematodoses harmful to fish farming.