Why this matters: Freshwater mussels are important sentinels of ecosystem health but have experienced dramatic population declines in the last century. Possible causes of the declines include pollution and habitat destruction or alteration as well as introduction of invasive species, overharvesting, lack of fish hosts, climate change, predation, genetic change, endocrine disruptors, and disease. Knowles et al. 2023 synthesizes current information to improve our knowledge of disease in freshwater mussels.

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Over 1,200 species of freshwater mussels occur worldwide. They provide the important ecosystem function of improving water quality via filter feeding. Long-lived sentinels of ecosystem health, freshwater mussels also serve as a food source and provide habitat for many additional wildlife species. Freshwater mussels are some of the most imperiled species in the world with nearly 40% assessed as near threatened, threatened or extinct. North America is a hotspot for mussel diversity with more than 300 species. Population declines in North America began 100 years ago and today 65% of freshwater mussels species are considered endangered, threatened or vulnerable with more than 30 having gone extinct in the last century. Possible causes of the declines include pollution and habitat destruction or alteration as well as introduction of invasive species, overharvesting, lack of fish hosts, climate change, predation, genetic change, endocrine disruptors, and disease. Investigations of disease as the cause of the population declines are limited. Knowles et al. 2023 was published to synthesize current disease information and offer standardized methods for disease investigations that will improve our knowledge of disease in freshwater mussels and how it might be contributing to population declines.