SFS Annual Meeting

5/23/2019  |   11:00 - 11:15   |  250 AB

THE FUTURE OF GLACIAL-FED STREAMFLOW IN THE AMERICAN WEST Perennial snow patches and glaciers are common to many high alpine environments. Less obvious high alpine glacial features are rock-covered glaciers and rock glaciers, where ice fills the voids between rocks. The geographic distribution of glaciers, debris-covered glaciers, and rock differ across the American West with more glaciers in the Pacific Northwest (Washington) and more rock glaciers in the south-central (Colorado). All glaciers provide two important streamflow services, supplying cool meltwater during the hottest, driest parts of the summer, and regulating seasonal streamflow variations, which mitigates the effects of drought. Runoff characteristics also differ. Streamflow from glaciers exhibit flashier daily flow variations and a faster runoff response with greater discharge to warmer weather. Rock debris insulates the subsurface ice from warm air temperatures and solar radiation slowing runoff response and reducing melt. However, as the climate warms, debris-covered and rock glaciers will persist longer into the future. The effect of glaciers on stream water quality (not including suspended sediment) depends the relationship between upstream glacier area and distance downstream. These processes will be examined in the context of a warming world.

Andrew G. Fountain (Primary Presenter/Author), Portland State University, andrew@pdx.edu;


Allison Trcka (Co-Presenter/Co-Author), Portland State University, atrcka@pdx.edu;


Bryce Glenn (Co-Presenter/Co-Author), Portland State University, brglenn@pdx.edu;


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5/23/2019  |   11:15 - 11:30   |  250 AB

DO ROCK GLACIERS PROVIDE REFUGIA FOR COLDWATER AND WETLAND-ADAPTED SPECIES UNDER WARMING CLIMATES? INSIGHTS FROM THE GREAT BASIN, USA Rock glaciers are ubiquitous alpine landforms, little recognized outside the cryosphere science community. In North America, they are common in all but the most humid mountain zones. Rock glaciers are recognized by their tongue-like forms, coarse, rocky surfaces, and oversteepened fronts. They form from periglacial as well as glacial processes (“equifinality). In cross section, they have rocky upper mantles and discontinuous lenses or strata of ice (permafrost) at depth. Unique micro-climates develop due to the open texture, which decouple internal environments from outside air, creating cold thermal environments even in summer. Rock glaciers can depress regional discontinuous permafrost elevation by 1000 m. Springs have high persistence even under multi-year droughts, and maintain water temperatures < 1°C year around. Because rocky mantles buffer matrices from warming and unique ventilation maintains cold temperatures, rock glaciers can lag in response to warming for decades to centuries. Their role as climatic refugia for cold-water-adapted fauna has been little explored but may prove significant. Further, wetland vegetation communities develop in front of rock glaciers, providing habitat for cool-adapted terrestrial species. Internal matrix environments also provide refugia for species that require protection from high daytime temperatures.

Constance Millar (Primary Presenter/Author), USDA Forest Service PSW Research Station, cmillar@fs.fed.us;


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5/23/2019  |   11:30 - 11:45   |  250 AB

IMPLICATIONS OF CLIMATE CHANGE FOR PHYSICOCHEMISTRY AND RESOURCE AVAILABILITY IN MOUNTAIN STREAMS OF SOUTHEAST ALASKA The Coast Mountains of southeast Alaska contain a diversity of watersheds ranging in elevation from sea level to more than 2500 meters and in landcover from old growth forest to alpine icefields and glaciers. Within this watershed mosaic, landcover and streamwater sources impart distinctive physical and chemical properties to streams that, in turn, structure resource availability and habitat suitability for native and anadramous fish species. In this study, we use a paired watershed approach to evaluate how differences in landcover impact stream physicochemistry. We instrumented two adjoining watersheds, one with glacier ice and perennial snowfields and one dominated by low-elevation forest and wetlands, with stream gages and in-situ water quality sensors to measure the physical properties of streamwater (temperature, conductivity, and DO) over the summer runoff season (May-October). We also collected regular grab samples to evaluate the availability and export of C, N, and P in streamwater and used drift nets to quantify organic and invertebrate drift. Our findings provide insight into the temporal drivers of aquatic resource availability and how mountain streams in southeast Alaska will evolve as glaciers and snowfields continue to be lost.

Eran Hood (Primary Presenter/Author), University of Alaska Southeast, ewhood@alaska.edu;


Jason Fellman (Co-Presenter/Co-Author), University of Alaska Southeast, jbfellman@alaska.edu;


J. Ryan Bellmore (Co-Presenter/Co-Author), Forest Service, Pacific Northwest Research Station, Juneau, AK, jbellmore@fs.fed.us;


Connor Johnson (Co-Presenter/Co-Author), University of Alaska Southeast, cmjohnson29@alaska.edu;


Mollie Dwyer (Co-Presenter/Co-Author), University of Alaska Southeast, mrdwyer@alaska.edu;


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5/23/2019  |   11:45 - 12:00   |  250 AB

FROM GLACIAL, TO SNOW, TO RAIN: EFFECTS OF HYDROLOGIC HOMOGENIZATION ON AQUATIC FOOD WEBS IN SOUTHEAST ALASKA Watersheds in southeast Alaska frequently contain a mosaic of glacier-, snow-, and rain-fed streams that have distinct hydrologic, temperature and nutrient regimes. However, as glaciers recede and precipitation shifts from snow to rain, the physical and chemical characteristics that make a glacial or snowmelt stream different from a rainwater stream may fade. Among the unforeseen consequences of this hydrologic homogenization could be the loss of unique food webs that sustain aquatic and terrestrial consumers. To explore this possibility we parameterized a food web model with physico-chemical data from glacial-, snow- and rain-fed streams in southeast Alaska, and used the model to predict the seasonal biomass dynamics of consumers and resources. Model results suggest that glacial-, snow-, and rain-fed streams exhibit asynchronies in the peaks and troughs periphyton and aquatic invertebrate availability. For mobile fish consumers that can track peaks in resource abundance within river networks, the presence of these asynchronies increased modeled fish growth. These findings suggest that climate change induced homogenization of watersheds may result in the loss of unique food web dynamics, which in turn, could undermine the capacity of watersheds to sustain consumer populations.

Jason Fellman (Co-Presenter/Co-Author), University of Alaska Southeast, jbfellman@alaska.edu;


Eran Hood (Co-Presenter/Co-Author), University of Alaska Southeast, ewhood@alaska.edu;


Matthew R. Dunkle (Co-Presenter/Co-Author), Department of Fish and Wildlife Science, University of Idaho, mdunkle@uidaho.edu;


J. Ryan Bellmore (Primary Presenter/Author), Forest Service, Pacific Northwest Research Station, Juneau, AK, jbellmore@fs.fed.us;


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5/23/2019  |   12:00 - 12:15   |  250 AB

ANALYSIS OF FOOD WEB TOPOLOGY ALONG A HEADWATER STREAM GRADIENT AND IMPLICATIONS FOR COMMUNITY RESILIENCE Understanding the structure and functionality of food webs is a key component of effective ecosystem management. Conceptualizing and quantifying aspects of food web topology is vital to identifying trends in community structuring and aiding in future predictive abilities. Headwater streams play a direct role in the integrity of downstream systems, affecting nutrient transport, primary production, and fisheries. Using long-term data collected from headwater streams at the H.J. Andrews Experimental Forest, I constructed food webs using the Cheddar package and WebBuilder function in R. These tools allow users to quantify web attributes such as connectance and generality, and therefore compare food webs along spatial and environmental gradients. Comparisons of communities without a top predator (Oncorhynchus clarkii clarkii) were made with more diverse webs in the river network to identify the influence that Cutthroat Trout plays in the structural complexity and stability of stream food webs. Finally, a non-metric multidimensional scaling analysis was preformed to assess the overall similarities and dissimilarities of all food webs in the headwater network. Implications of structural heterogeneity to community stability are covered, and preliminary results are presented from a subset of the food web data analyzed.

Lauren Zatkos (Primary Presenter/Author), Oregon State University, lauren.zatkos@oregonstate.edu;


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