Predicting Cold-Water Fish Habitat in Lakes of the Glacial Lakes Region Under Changing Land Use and Climate Regimes

As part of a USGS national fish habitat assessment, the goal of the study described here is to predict the impacts of future climate and land use change on coldwater fish habitat in the glacial lakes in Minnesota, Wisconsin, and Michigan. We developed regional regression models that predict annual nutrient loading rates to lakes based on land use (agriculture fraction and urban fraction) and climate (runoff depth) using data for 256 coldwater lakes in the three state region. The regression models were then used to project future changes in TP concentration and trophic status based on projected changes in land use and climate. Projected increases in agricultural land use were found to give the largest predicted impacts on future lake trophic status. The predicted changes to trophic status are being combined with predicted changes in air temperature to estimate regional changes in oxythermal habitat and determine the resiliency of coldwater habitat to climate and land use change.