Modeling Site to Landscape Scale Hydrological Features Regulating River Temperatures and Habitats for Brook Trout and Atlantic Salmon

Identifying thermal habitats in rivers with our changing climate is an emerging challenge for protecting and sustaining coldwater ecosystems.  Summer cold-water and winter warm-water areas can provide critical refugia from extreme conditions, i.e., maximum temperature tolerability and ice accumulations, respectively.  We are working to define and identify critical thermal habitats for brook trout (Salvelinus fontinalis) and Atlantic salmon (Salmo salar).  Using  geo-referenced, thermal infrared images of summertime river temperatures, we are modelling the physical attributes of catchments and riverscapes across variable spatial scales to predict instream temperatures.  In addition, we are examining how such imagery might predict the actual critical thermal habitats.  Our initial, partial-least-square-regression models suggest temperatures of tributary catchments to the main river are best predicted by their slope and density of wetlands and mixed forest.  We will present additional temperature models based on riverscape features.  Initial analyses suggests that thermal infrared images are accurate predictors of critical summer habitats for trout and salmon, except that not all predicted habitats are used because of physical, instream constraints, e.g., minimum depth requirements for adults and connectivity-accessibility limits.