Freshwater mussels ( anodonta anatina ) reduce transmission of a common fish trematode (eye fluke, diplostomum pseudospathaceum )

Recent results suggest that bivalves can play an important role in restraining the spread of various aquatic infections. However, the ability of mussels to remove free-living stages of macroparasites and reduce their transmission is still understudied, especially for freshwater ecosystems. We investigated the influence of the common freshwater mussel ( Anodonta anatina ) on the transmission of a trematode (eye fluke, Diplostomum pseudospathaceum ), which frequently infects fish in farms and natural habitats. In our experiments, mussels caused a significant decrease ( P −1 on average (about 4-fold in 2 h). Individual clearance rates of mussels were 0·6‒3·7 L per hour (mean 1·9). These tests were followed by experimental infections of rainbow trout ( Oncorhynchus mykiss ) with different doses of D. pseudospathaceum cercariae in the presence or absence of mussels. Exposure of fish to cercariae in the presence of mussels significantly ( P