6533b7d1fe1ef96bd125cd07

RESEARCH PRODUCT

Parasites in sympatric populations of native and invasive freshwater bivalves

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An increasing threat to local, native freshwater mussels (Unionida)—an ecologically important but globally alarmingly declining group— is the invasion by exotic bivalves. The Enemy Release Hypothesis predicts that introduced species should benefit from enemy-mediated competition because they are less likely to be harmed by natural enemies, such as parasites, than their native competitors. We investigated within-site differences in parasitism between sympatric native (tot. five spp.) and invasive (tot. three spp.) bivalves in eight northern European waterbodies, which harboured totally 15 parasite taxa. In paired comparisons using within-site averages, the mean number of parasite species in the native bivalves was 2.3 times higher, and the sum of parasite prevalences 2.4 times higher, than in the invasive bivalves. This may lead to enemy-mediated compet- itive release of invaders and contribute to the success of invasive freshwater bivalves, in general. However, while the invasive clam Corbicula fluminea was completely free from parasites, parasite parameters of the other invader, Sinanodonta woodiana, were relatively high, indicating that the role of parasites can be invader-specific and urges further research. Under- standing the factors affecting success of freshwater bivalve invasions, such as parasitism, can aid invasion control and conservation of local, native (endangered) bivalves. Open access funding provided by University of Jyväskylä (JYU). Co-authors’ cooperation was initiated with the support of the Poznan ́ City Council under the ‘‘Academic and Scientific Poznan ́’’ Program. The study was funded by Estonian Ministry of Education and Research (institutional research funding project IUT 21-2 to Tiina Nõges) and by Estonian Research Council, Mobilitas Pluss research project MOBJD29. This study was also supported by the Polish Minister of Science and Higher Education, under the program ‘‘Regional Initiative of Excellence’’ in 2019–2022 (Grant No. 008/RID/2018/19), by Poznan ́ University of Life Sciences, University of Jyva ̈skyla ̈, and by CNR Short Term Mobility Project 2016. We thank Henryk Gierszal and Henn Timm for valuable assistance in field and laboratory. Open access funding provided by University of Jyväskylä (JYU). Co-authors’ cooperation was initiated with the support of the Poznan ́ City Council under the ‘‘Academic and Scientific Poznan ́’’ Program. The study was funded by Estonian Ministry of Education and Research (institutional research funding project IUT 21-2 to Tiina Nõges) and by Estonian Research Council, Mobilitas Pluss research project MOBJD29. This study was also supported by the Polish Minister of Science and Higher Education, under the program ‘‘Regional Initiative of Excellence’’ in 2019–2022 (Grant No. 008/RID/2018/19), by Poznan ́ University of Life Sciences, University of Jyva ̈skyla ̈, and by CNR Short Term Mobility Project 2016. We thank Henryk Gierszal and Henn Timm for valuable assistance in field and laboratory.