Coupled Atmosphere-Lake Climate Modeling and Influence On Great Lakes Fish

The Coupled Hydrosphere-Atmosphere Research Model (CHARM) is a regional climate model optimized for the Laurentian Great Lakes basin, which includes coupling of the atmosphere to 1-dimensional lake temperature profiles and temperature diffusion.  It was applied to climate change scenarios and used to project climate variables, including direct projection of lake temperatures.  Previous observations of more rapid increases in summer lake surface temperature than nearby air temperature are supported by this model, with the apparent cause being earlier and stronger thermal stratification of the lake.  When the resultant warmed lake temperatures are inserted into bioenergetics models of Chinook salmon (Oncorhynchus tshawytscha), lake trout (Salvelinus namaycush), and steelhead (O. mykiss), and under the assumption that prey availability is unlimited, the growth and consumption rates of all of these species increased.  Under other assumptions, the lake trout and steelhead appear to adapt more readily to warmer temperatures than the Chinook salmon.