A method for long-term year-round water temperature monitoring in salmonid spawning habitats in remote dynamic streams

Warming temperatures have added urgency to characterizing the thermalscapes and thermal tolerances of cold-adapted fishes to effectively manage and conserve such species. This is especially relevant at high latitude and high elevation streams, which are experiencing rapid environmental changes, yet are data-poor, remote, and difficult to access. Here, we describe a method to assess temporal and spatial variation in surface and hyporheic water temperatures that can be effectively deployed to remain year-round in remote dynamic streams. We then demonstrate the utility of this method by assessing Dolly Varden Salvelinus malma spawning sites in a remote river. Characterizing and quantifying the amount of viable thermal habitat for cold-adapted species improves predictions of how warming may affect high latitude and high elevation stream ecosystems. Together with species-specific thermal tolerances, this information can then be used to identify the thermal refugia that are essential for conservation of endemic species, and assess risks associated with range expansions of potentially colonizing species.