Fishes, mussels, crayfishes, and aquatic habitats of the Hoosier-Shawnee ecological assessment area

The Hoosier-Shawnee Ecological Assessment Area, part of the Coastal Plain and Interior Low Plateau physiographic provinces, includes 194 native fish species, 76 native mussel species, and 34 native crayfish species. Five of the subregions (e.g., Mississippi Embayment) that make up the assessment area were recently ranked as either globally or bioregionally outstanding aquatic resource areas. Fish, mussel, and crayfish diversity was analyzed for richness and density within and between the 39 hydrologic units that make up the assessment area. Species richness averaged 76 fish and 26 mussel species per hydrologic unit, and ecological units positioned as ecotones tended to be associated with primary levels of richness. At least 12 fish species are of conservation concern within the Hoosier and Shawnee National Forest boundaries; another 10 species are poorly known and need status surveys or other forms of conservation evaluation. Nearly 30 mussel species and 10 crayfish species are of conservation concern in the area, but fewer than 10 of these actually occur within national forest boundaries or would be directly affected by national forest activities. Commercial and recreational fisheries are popular in the region, and commercial exploitation of both mussels and crayfishes occurs in the assessment area. The most valuable and unique aquatic habitats in the area include springs, spring runs, karst aquifers, wetlands, swamps, mainstem large rivers, and upland, gravel-bottomed streams in both the Hoosier and Shawnee National Forests. The responsibility and challenges the USDA Forest Service shoulders in manageing and protecting the unique aquatic resources on its properties are staggering, especially in regard to the recently acknowledged global need for usable fresh water.