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Togiak National Wildlife Refuge

Western Alaska is one of the fastest warming regions on the globe and recent trends are expected to continue into the next century, likely having substantial effects on the aquatic resources of this region. While increased air temperatures will have direct effects on water temperatures, indirect effects due to changes in precipitation, groundwater characteristics, and flow regimes may have much larger effects on aquatic ecosystems. Coastal watersheds of Western Alaska are expected to receive 25-50% more snow and 18-25% more rain in the next century. Future “climate warming” may actually cool some streams if the ratio of snow to rain increases for coastal watersheds, while rain-dominated streams are likely to become...
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When resources are spatially and temporally variable, consumers can increasetheir foraging success by moving to track ephemeral feeding opportunitiesas these shift across the landscape; the best examples derive from herbivore–plant systems, where grazers migrate to capitalize on the seasonal waves ofvegetation growth. We evaluated whether analogous processes occur in watershedssupporting spawning sockeye salmon (Oncorhynchus nerka), askingwhether seasonal activities ofpredators and scavengers shift spatial distributionsto capitalize on asynchronous spawning among populations of salmon. Bothglaucous-winged gulls and coastal brown bears showed distinct shifts in theirspatial distributions over the course of the summer,...
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How local geomorphic and hydrologic features mediate the sensitivity of stream thermal regimesto variation in climatic conditions remains a critical uncertainty in understanding aquatic ecosystem responsesto climate change.We used stable isotopes of hydrogen and oxygen to estimate contributions of snow and rainfallto 80 boreal streams and show that differences in snow contribution are controlled by watershed topography.Time series analysis of streamthermal regimes revealed that streams in rain-dominated, low-elevation watershedswere 5–8 times more sensitive to variation in summer air temperature compared to streams draining steepertopography whose flows were dominated by snowmelt. This effect wasmore pronounced...
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Climate change is expected to impact the thermal regimes of streams and otherfreshwater ecosystems (Schindler 2001, Malmqvist and Rundle 2002, Poff et al. 2002). Whileincreased air temperatures will have direct effects on water temperature, indirect effects due tochanges in precipitation patterns, groundwater characteristics, and flow regimes (Perkins et al.2010) may have much larger effects. We explored 1) how variation in hydrologicalcharacteristics of streams mediate their thermal regimes, 2) how geomorphic features ofwatersheds regulated stream water sources and, therefore, thermal characteristics, and 3) whetherpatterns of thermal variation among streams correlate with the life-history characteristics ofPacific...
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Intraspecific variation in the seasonal reproductive timing of Pacific salmon (Oncorhynchus sp.) has importantimplications for the resilience of salmon and for organisms in freshwater and terrestrial communities that dependon salmon resources. Stream temperature has well known associations with salmon spawn timing buthow stream and watershed geomorphology relates to the variation in salmon spawn timing is less understood.We used multivariate statistics applied to five environmental variables to compare conditions across36 watersheds in the Wood River basin in southwest Alaska. We found that the environmental conditionsin the first two axes of a principal components analysis (PCA) explained 76% of the variation in...
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