Predicted Impacts of Climate Change on Stream Habitat and Brook Trout Populations in the Eastern US

Throughout its native range in the Eastern U.S., the brook trout Salvelinus fontinalis is a culturally, economically, and ecologically important species that is sensitive to warming stream temperatures and habitat degradation. Our study region encompasses the historic native range of brook trout in the Eastern U.S., which includes the northeastern states and follows the Appalachian Mountains south to Georgia. Brook trout have been extirpated throughout much of this region due to a number of human activities and land cover alterations, and are often limited to higher elevation streams with suitable water temperatures at the southern margin of their range. The purpose of this assessment is to determine what impacts projected future land use and climate changes might have on the condition of stream habitat to support self-sustaining brook trout populations throughout the next century. We are compiling brook trout occurrence and continuous stream temperature data from state and federal agencies throughout the study region. Other datasets included in this assessment represent both current and future atmospheric, landscape and stream habitat conditions, including geology, landform, potential landscape stressors (e.g. road density), current and projected climate (e.g. air temperature), and current and projected land use/cover. All data will be summarized and attributed to individual stream reaches of the NHDplus dataset, which is the base layer for our GIS environment. We are classifying habitat suitability based on relationships between recent observations of brook trout and predicted stream temperature, predicted stream flow, land use, and a number of potential habitat stressors under current conditions. We will then use these relationships with land use and climate change projections to predict potential changes in stream habitat and impacts on brook trout distribution, with the assumption that current brook trout – stressor relationships will not change in the near future. Previous studies have suggested that warmer temperatures associated with climate change would result in large losses in brook trout range, especially throughout the southern Appalachians. We expect to see impacts as a result of warmer air temperatures, but we are not sure what impacts precipitation changes might be predicted to have on brook trout. To date there have been no studies predicting the impacts of land use change on brook trout, but we expect that increasing urbanization will result in the loss of suitable stream habitat while reforestation of agricultural areas might result in some unsuitable stream reaches becoming suitable in the future.