Understanding and Predicting Heterogeneous Thermal Responses of Inland Waters to Climate Warming

Inland waters are warming, with consequences for ecosystem functions and fisheries management. Despite well documented heterogeneous responses of lakes and streams to climate change, predictions of future fish thermal habitat are often projected at coarse resolutions that ignore variability among lakes. Conversely, understanding and predicting thermal refugia of individual water bodies is an important component of climate adaptation for management agencies. Fish populations in some temperate lakes and streams have experienced range shifts, extirpations, and changes in species dominance amid complex local and regional factors, while other nearby waters are comparably resilient. Our project leverages several emerging data networks for water temperature and fisheries observations, and mechanistic modeling of contemporary (1979-2015) thermal habitat metrics for thousands of lakes in WIsconsin, Minnesota, and Michigan. These data allow us to better understand heterogeneous responses to climate warming, including varying warming rates across lakes. We found that lake-specific properties, including morphometry and water clarity, influence resilience to climate change. These same properties also help explain among-lake differences in the magnitude and direction of observed changes in fish distributions. Finally, we project habitat in the late 21st century for these lakes and highlight opportunities for fisheries management on climate-resilient lakes.