Is That the Best Metric for Predicting Climate Change Effects on Brook Trout?

To predict climate change effects on riverine fish, it is common to use a single climate metric (e.g., mean July water temperature) that is associated with the distribution of a selected species or community. There are a large number of very similar, alternative metrics that could also be used, however, and the magnitude of climate change could vary among these metrics. We compared variation among multiple climate metrics in predicted climate change effects on water temperature and Brook Trout Salvelinus fontinalis in the Eastern U.S. We first briefly describe the models used to predict water temperature and Brook Trout occurrence, and then quantify predicted changes under three climate models and multiple metrics. Not surprisingly, the timing, magnitude and location of predicted changes varied greatly (up to 40% difference in predicted habitat losses) among the three climate models. However, we also found that predicted losses in the region varied by up to 20% among the climate metrics, and that the climate metric most highly correlated with empirical Brook Trout occurrence greatly underestimated changes. These results suggest that multiple metrics may need to be considered in predicting climate change effects, especially when predictions may inform management or conservation decisions.