Potential Impacts of Climate Warming on Aquatic Ecosystems in the Northern Rockies: Implications for Native Species Conservation

Climate change is rapidly altering aquatic ecosystems worldwide.  Warming in the mid- to high-latitudes is occurring at two to three times the rate of the global average, and in high-elevation mountainous regions recent data show increased magnitude and rate of warming with extensive loss of glaciers and snowpack.  These changes are likely to shift patterns in distribution, abundance, and phenology of many cold-water dependent species.  Therefore, we partnered with scientists from the Forest Service and Trout Unlimited to examine how climate change may be impacting aquatic ecosystems throughout the interior western United States.  Trend data indicate that the Northern Rocky Mountains are experiencing earlier and more rapid snowmelt in the spring, warmer drier summers, increased winter flooding, and loss of permanent snow and ice masses.  Our regional downscaled climate models suggest that these changes in the hydrological cycle will likely continue to warm perennial streams, thereby threatening the suitability of habitats used by native salmonids, including the threatened bull trout Salvelinus confluentus, and rare alpine invertebrates, such as the ESA-petitioned endemic stonefly L. tumana.  Furthermore, these changes may provide habitat conditions that favor introduced species, such as rainbow trout which hybridize with native westslope cutthroat trout Oncorhynchus clarkii lewisi.  It is increasingly urgent to assess and monitor the status of species living in mountainous aquatic systems in order to fully understand their basic ecological requirements and use this information to model the potential impacts of climate warming across spatial scales from local to global.