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.