Biogeographic Patterns of Inland Lake Fish Communities at Isle Royale, Voyageurs, and Sleeping Bear Dunes National Park Units

Composition of the inland lake fish communities in Isle Royale (ISRO), Voyageurs (VOYA), and Sleeping Bear Dunes (SLBE) parks were examined as examples of modern biological communities shaped by post-glacial history. We examined the roles of historical biogeography, local habitat factors, and human impacts in shaping modern communities. We also examined the potential for future changes in community composition in light of pending global climate change. Within parks, differences in community composition were correlated with a gradient of lake habitats determined by lake size and depth and corresponding changes in environmental-physical characteristics. A cline of sequential losses of cool- and coldwater species and gains of thermally tolerant and warmwater species from ISRO to VOYA to SLBE suggests a pattern of community assembly associated with different degrees of climate change across the three parks since the early Holocene. The strong underlying gradient of temperature provides an example of the influence of historical climate change in shaping modern communities. Application of climate change models identified refuge lakes for heritage communities. To facilitate the preservation of heritage lake communities in the face of an anticipated warming climate in the 21st century, we provided recommendations for research, monitoring, conservation, and management.