Under the cover of ice: Trematode infections affect survival and growth of wintering mussels

ABSTRACT: Parasites play many regulating roles that are increasingly recognized in different ecosystems. In coastal ecosystems, the trematode Himasthla elongata infects blue mussel Mytilus edulis, a foundation species that shapes the functioning of intertidal communities. Although the largest impacts of infections occur during the summer months, the parasites form long-lived cysts that can be harmful to their host mussels under winter conditions. Here, we experimentally show that even moderate levels of infection by H. elongata have a detrimental effect on the survival and growth rate of wintering blue mussels. These parasite-induced costs during winter may potentially affect populations of blue mussels in coastal habitats, with ramifications for the whole ecosystem.