Using a spatially explicit stream temperature model to assess potential effects of climate warming on bull trout habitats

Abstract

As the Flathead River Basin (FRB) undergoes change caused by a warming climate, scientific studies evaluating habitats and species most susceptible to the impacts of climate change will become increasingly important. Here, we seek to identify biologically meaningful physiological thresholds of bull trout in the FRB by modeling stream temperature and using the model as a tool to predict thermal changes caused by a warming climate. Specifically, we developed a spatially explicit stream temperature model to quantify and explore the potential range of thermal warming effects, using the case study of bull trout populations in the FRB. Our objectives were to: i) compare spatial and non-spatial statistical models used to predict stream temperatures throughout the FRB; ii) apply a spatially explicit model to estimate thermal thresholds for spawning and rearing and foraging migrating and overwintering bull trout habitats; iii) predict thermal changes under a range of future climate scenarios; and iv) investigate model behavior and inform future research decisions. Development of spatially explicit models, such as the one described here, will create an ideal opportunity to build collaborative relationships through research so that scientists can further understand how climate change will impact freshwater aquatic ecosystems. In particular, model results may be used to perform ecosystem assessments; inform future research needs; and develop conservation plans with broad applications that reach beyond the Flathead system.