Natural and anthropogenic factors predict the presence of two freshwater mussels (Bivalvia: Unionidae) in Illinois, USA

AbstractOver half of the 80 freshwater mussel species that historically occupied Illinois are now extinct, extirpated, endangered, or threatened. Two species of conservation concern that warrant further investigation are Ellipse (Venustaconcha ellipsiformis) and Spike (Eurynia dilatata). Ellipse have experienced a 30% range contraction in Illinois and are a focal species for a regional conservation initiative in the state. Spike have experienced a range contraction of 55% in Illinois, despite remaining relatively common in bordering states. Several stressors have been proposed as causes of declines in both species, such as habitat fragmentation, hydrologic alteration, pollutants, and availability of fish hosts to aid mussel dispersal. Ultimately, developing effective conservation and management actions for these species requires identifying the environmental conditions that most strongly influence their persistence. Our objective was to identify the habitat features and environmental conditions that best ...