Canadian freshwater mussels and their host associations

Freshwater mussels (order Unionida) are one of the world’s most imperiled
taxonomic groups of animals. These mussels have an obligate parasitic
larval phase wherein the larva (usually, a glochidium) must attach to a
suitable host to complete its metamorphosis into a juvenile mussel. This
review synthesizes the current knowledge on the hosts of all 55 species of
freshwater mussels in Canada compiled from 264 citations, 70 of which were
newly identified by this review. As of October 2023, 827 mussel-host
interactions have been documented. The Winged Floater and the Lake Floater
currently have no known hosts, with 14 other species having only a single
associated evidence type. This review provides an updated library of
current knowledge on hosts of Canadian unionids, discusses notable trends
in the data, and outlines outstanding knowledge gaps to be addressed in
future studies. Relatively few studies aimed at identifying unionid hosts
have been conducted in Canadian waters. This lack of understanding of
relevant ecological and climatic context has consequences for the
development of appropriate conservation actions in Canada.