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PROJECTED CHANGES IN SNOWMELT TIMING ARE POISED TO ALTER MACROINVERTEBRATE STRUCTURE IN SIERRA NEVADA STREAMS

Climate change is projected to advance median snowmelt runoff in the Sierra Nevada up to two months by 2080. Changes in peak-flow timing could impact stream biodiversity by filtering non-adaptive life histories, but research on the topic is scarce. Here, we assessed whether snowmelt-timing controls stream macroinvertebrate communities by analyzing data from the SWAMP program. We first calculated abundance and rarefaction-based taxa richness in 30 sites mostly within the Owens Valley Watershed near Mammoth Lakes, California. We then created Spatial Stream Networks (SSN) to test whether snowmelt-associated parameters (day of year, slope, average stream temperature, and groundwater influence) explained variation in macroinvertebrate abundance or taxa richness across the river network. Stream Temperature negatively influenced both abundance and taxa richness, while day of the year (DOY) and groundwater had positive and negative effects on abundance, respectively. Our results suggest that increases in summer stream temperature due to earlier snowmelt could alter macroinvertebrate abundance and richness in the area, with timing having additional effects relative to temperature change alone. Experimentation is needed to confirm our SSN model results and identify the mechanisms that control macroinvertebrate community responses to altered snowmelt timing.

Kyle Leathers (Primary Presenter/Author), University of California Berkeley, kyle_leathers@berkeley.edu;


Albert Ruhi (Co-Presenter/Co-Author), Department of Environmental Science, Policy, and Management, University of California Berkeley, albert.ruhi@berkeley.edu;