Mussels depend on a variety of fish species to disperse their larvae. If these fishes disappear, so do the mussels. Then other species that depend on the fishes and mussels disappear. Degraded, species-impoverished streams and rivers affect the human community, too, through diminished economic and recreational opportunities.

Historically, Illinois was home to 79 mussels species. Today six species are extinct, 11 have disappeared from the state, 23 are listed as threatened or endangered, and a dozen others are rare or limited in their distribution. Mussels’ decline is the result of habitat destruction through dredging, damming, discharge of sewage and toxic waste, and runoff of water polluted with agricultural and garden chemicals.

In 1992, Shedd launched its freshwater mussel program to study vanishing mussel fauna in the Midwest. At that time, few conservation or governmental agencies had turned their attention to these biologically sensitive animals.

In partnership with the Illinois Department of Natural Resources, Shedd conducts mussel field surveys, systematically sampling the state’s major river systems, including the Sangamon, Green, Fox and Illinois. Each summer, Shedd staff and volunteers travel to assigned creeks and rivers to collect, identify, count and then release mussels.

From these surveys, researchers can identify long-term changes in the condition and use of the state’s rivers and streams — and develop conservation programs for mussels and their habitats. Data is also being utilized by municipalities and conservation groups to enact local plans to protect watersheds.