Stoneflies (Plecoptera) are the most environmentally sensitive of freshwater insects. They are recognized the world over as such and their decline has been documented in Europe and North America. A dataset of 30,355 specimen records, Maximum Entropy (Maxent) software, and BIOCLIM variables derived from downscaled climate data were used to compare the pre-European settlement and future geographic distributions of 78 of 155 stonefly species that occur in Illinois, Indiana, Iowa, Michigan, Minnesota, Ohio, and Wisconsin. Maximum temperature in the warmest month was predicted to increase by up to 4⁰ across much of the Upper Midwest Great Lakes Landscape Conservation Cooperative (UMGLLCC) by 2100. Rainfall in the driest month was not predicted to change appreciably during this time frame. Approximately 70% of 78 species and seven of eight families were predicted to experience dramatic range loss. Five species were predicted to increase in range by 100 to 300%. Four of the five are large river, warmwater species that were predicted to migrate northward as large, northern rivers warm. These predictions suggest that mismatches in predatory/prey resources may occur and that numerical criteria used by states for water quality assessment may require reassessment. The stonefly assemblage in the Midwest is in danger of going through a second drastic reduction by 2100, making it imperative that conservation organizations begin now to protect them. Suggestions include increasing forest cover alongside rivers and streams and improving the connectivity of rivers to allow migration from the south. The presence of Wisconsinan aged till and lake plain between southern, species rich areas and northern areas may act as a barrier to future dispersal, necessitating human aided migrations if conservation of stoneflies is accepted as a priority. Stoneflies may well be surrogates for the fate of other aquatic insects (e.g. mayflies (Ephemeroptera) and caddisflies (Trichoptera)). This assertion will be tested over the next year under a phase II contract with the Department of the Interior, US Fish and Wildlife Service.
|INHS Technical Report 2013 (22)