Effects of Ammonia on Freshwater Mussels
in the St. Croix River

The St. Croix River contains a diverse and abundant group of freshwater mussels. The St. Croix is one of the few rivers in the Midwest not substantially affected by the invasion of the exotic zebra mussel, which encrusts and kills native freshwater mussels. Increased concentrations of ammonia in river sediments, however, poses a significant threat to mussels.

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Effects of Ammonia on Unionid Mussels: A Potential Threat to Their Biodiversity in the St. Croix National Scenic Riverway