Citation:

Tonina, D., J. McKean, D. Isaak, R. Benjankar, C. Tang, AND C. Qiuwen. Climate Change Shrinks and Fragments Habitats for Salmon in a Snow-Dependent Region. GEOPHYSICAL RESEARCH LETTERS. American Geophysical Union, Washington, DC, 49(12):e2022GL098552, (2022). https://doi.org/10.1029/2022GL098552

Impact/Purpose:

The large majority of climate change research for aquatic organisms has focused on stream water temperature and discounted the importance of flow changes as precipitation changes. Using 1-meter resolution map supporting a series of linked flow and fish habitat quality models, our research describes how observed historical flow regime changes and future projected changes are affecting local habitat quality, distributions, and connectivity for a salmon population. We demonstrated that as climate change continues to change flow regimes in snow dependent regions, it will cause fragmentation and reduce the overall volume of available habitats in headwater streams where salmon and other cold-water fish species spawn and rear.

Description:

Climate change threatens biodiversity through global alteration of habitats, but efficient conservation responses are often hindered by imprecise downscaling of impacts. Besides thermal effects, warming also drives important ancillary environmental changes, such as when river hydrology evolves in response to climate forcing. Earlier snowmelt runoff and summer flow declines are broadly manifested in snow-dependent regions and relevant to socioeconomically important cold-water fishes. Here, we mechanistically quantify how climate-induced summer flow declines during historical and future periods cause complex local changes in Chinook salmon (Oncorhynchus tshawytscha) habitats for juveniles and spawning adults. Changes consisted of large reductions in useable habitat area and connectivity between the main channel and adjacent off-channel habitats. These reductions decrease the capacity of freshwater habitats to support historical salmon abundances and could pose risks to population persistence in some areas.

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