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Floods, spatially complex water flows, and organism movements all generate important fluxes of aquatic-derived materials into terrestrial habitats, counteracting the gravity-driven downhill transport of matter from terrestrial-to-aquatic ecosystems. The magnitude of these aquatic subsidies isoften smaller than terrestrial subsidies to aquatic ecosystems but higher in nutritional quality, energy density, and nutrient concentration. The lateral extent of biological aquatic subsidies is typically small, extending only a few meters into riparian habitat; however, terrestrial consumers often aggregate on shorelines to capitalize on these high-quality resources. Although the ecological effects of aquatic subsidies remain...
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How local geomorphic and hydrologic features mediate the sensitivity of stream thermal regimes to variation in climatic conditions remains a critical uncertainty in understanding aquatic ecosystem responses to climate change. We used stable isotopes of hydrogen and oxygen to estimate contributions of snow and rainfall to 80 boreal streams and show that differences in snow contribution are controlled by watershed topography. Time series analysis of stream thermal regimes revealed that streams in rain-dominated, low-elevation watersheds were 5–8 times more sensitive to variation in summer air temperature compared to streams draining steeper topography whose flows were dominated by snowmelt. This effect was more pronounced...
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In this first worldwide synthesis of in situ and satellite-derived lake data, we find that lakesummer surface water temperatures rose rapidly (global mean = 0.34°C decade1) between 1985 and2009. Our analyses show that surface water warming rates are dependent on combinations of climate andlocal characteristics, rather than just lake location, leading to the counterintuitive result that regionalconsistency in lake warming is the exception, rather than the rule. The most rapidly warming lakes are widelygeographically distributed, and their warming is associated with interactions among different climatic factors—from seasonally ice-covered lakes in areas where temperature and solar radiation are increasing whilecloud...
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Picea migration across Alaska was examined in three studies: an analysis of one paleoecological record, an assessment of stomates as a tool to detect first local occurrence, a quantification of Picea migration patterns from investigations of new metrics and uncertainty factors. Pollen, stomates and macrofossils were analyzed with a sediment core from Jan Lake, east-central Alaska. Picea arrival at Jan Lake is within 200 years of its arrival at other AMS-dated sites across eastern and central Alaska. Evidence is found for a slight mid-Holocene Picea decline at Jan Lake, intermediate in magnitude between no decline to the east and a larger decline to the west. Stomates were investigated as a proxy for local Picea...
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Increasing amounts and types of timely and accurate data are required for monitoring to ensure compliance with natural resource regulatory requirements. This study developed a cost-effective method to partially fulfill these data requirements using super large scale aerial photography (Scale: greater than 1:2,000). Two synchronized, metric, Rolleiflex 70mm (2.76in) cameras mounted 12m (40ft) apart on a rigid platform and carried at 5.6 km/hr (3 knots) by a helicopter collected this high resolution, 3D imagery from Alaska and Washington. The overlapping photo pairs provided 3D views of natural resource objects as fine as twigs. The 12m (40ft) inter-camera distance improved ground visibility between tree crowns of...
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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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Global environmental change has influenced lake surface temperatures, a key driver of ecosystem structureand function. Recent studies have suggested significant warming of water temperatures in individual lakesacross many different regions around the world. However, the spatial and temporal coherence associatedwith the magnitude of these trends remains unclear. Thus, a global data set of water temperature isrequired to understand and synthesize global, long-term trends in surface water temperatures of inlandbodies of water. We assembled a database of summer lake surface temperatures for 291 lakes collectedin situ and/or by satellites for the period 1985–2009. In addition, corresponding climatic drivers (airtemperatures,...
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The high magnitude of projected climate change in northern latitudes represents a serious concern to the persistence of Alaskan plant species with limited geographic distributions or narrow habitat requirements. To address this potential vulnerability, we review the distribution patterns of Alaska’s rare plants and initial results from current and future habitat suitability models for 34 rare plants. Hotspots of rare taxa in the state are concentrated in the Aleutian Islands, southeastern Alaska, interior Alaska and Brooks Ranges, and the Arctic Coastal Plain. Approximately 60% of Alaska’s rare species are found at high elevations, islands, or adjacent to the Arctic Ocean and therefore appear to lack clear...
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Fisheries management need satisfy a balance of ecological and socioeconomic objectives. As these two components are inseparable in any fishery, management solutions need incorporate both. In this dissertation, I present three essays that highlight the importance of considering both biology and socioeconomics in natural resource management science, presenting risk assessment and risk management as pragmatic means to frame natural resource issues and formulate solutions that satisfy multiple and conflicting objectives. Chapter I, Global Fishery Development Patterns Are Driven by Profit but not Trophic Level , presents interpretation of global fishery development data in light of the drivers of fishing impacts: profitability....
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Spawning migrations of Pacific salmon (Oncorhynchus spp.) to coastal watersheds provide a rich resource subsidy to freshwater consumers. However, variation in thermal regimes and spawning activity across the landscape constrain the ability of poikilothermic consumers to assimilate eggs and carcasses. We investigated how sockeye salmon (Oncorhynchus nerka) spawning density and stream temperature affect the growth, body condition, and fatty acid composition of juvenile coho salmon (Oncorhynchus kisutch), a known egg predator, in seven tributaries of the Wood River in Southwest Alaska. We compared mean body size of juvenile coho salmon in late summer among 3–7 years per stream and found that the largest mean size occurred...
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An important unresolved question is how populations of coldwater-dependent fishes will respond to rapidly warming water temperatures. For example, the culturally and economically important group, Pacific salmon (Oncorhynchus spp.), experience site-specific thermal regimes during early development that could be disrupted by warming. To test for thermal local adaptation and heritable phenotypic plasticity in Pacific salmon embryos, we measured the developmental rate, survival, and body size at hatching in two populations of sockeye salmon (Oncorhynchus nerka) that overlap in timing of spawning but incubate in contrasting natural thermal regimes. Using a split half-sibling design, we exposed embryos of 10 families...
Categories: Data, Publication; Types: Citation, Map Service, OGC WFS Layer, OGC WMS Layer, OGC WMS Service; Tags: Academics & scientific researchers, CLIMATE CHANGE IMPACT ASSESSMENT MODELS, CLIMATE CHANGE IMPACT ASSESSMENT MODELS, DATA REFORMATTING, DATA REFORMATTING, All tags...
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Wetlands in the remote mountains of the western US have undergone two massive ecological “experiments” spanning the 20th century. Beginning in the late 1800s and expanding after World War II, fish and wildlife managers intentionally introduced millions of predatory trout (primarily Oncorhynchus spp) into fishless mountain ponds and lakes across the western states. These new top predators, which now occupy 95% of large mountain lakes, have limited the habitat distributions of native frogs, salamanders, and wetland invertebrates to smaller, more ephemeral ponds where trout do not survive. Now a second “experiment” – anthropogenic climate change – threatens to eliminate many of these ephemeral habitats and shorten...
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This research is directed at addressing questions about the role of social networks in the evolution of social complexity in hunter-gatherers. Existing models of emergent complexity in northern hunter-gatherers point to the role of interaction across ecological zones in the development of a specialized maritime economy, increasingly complex social organization, and social inequality. Yet archaeological evidence of interaction remains, for the most part, unevaluated in relationship to these hypotheses. This study tests the hypothesis that the development and maintenance of social alliance and exchange systems was critical to the emergence of social complexity in Arctic peoples. Patterning of ceramic formal and compositional...
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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...
    map background search result map search result map Amphibians in the climate vise: loss and restoration of resilience of montane wetland ecosystems in the western US - Journal Article Describing the postglacial pattern and rate of Picea expansion in Alaska using paleoecological records From Tundra to Forest: Ceramic Distribution and Social Interaction in Northwest Alaska Late glacial and Holocene fire history in the southcentral Brooks Range, Alaska; direct and indirect impacts of climatic change on fire regimes Rapid and highly variable warming of lake surface waters around the globe Association between geomorphic attributes of watersheds, water temperature, and salmon spawn timing in Alaskan streams Watershed geomorphology and snowmelt control stream thermal sensitivity to air temperature Thermal adaptation and phenotypic plasticity in a warming world: Insights from common garden experiments on Alaskan sockeye salmon Thermal constraints on stream consumer responses to a marine resource subsidy Riding the crimson tide: mobile terrestrial consumers track phenological variation in spawning of an anadromous fish Subsidies of Aquatic Resources in Terrestrial Ecosystems A global database of lake surface temperatures collected by in situ and satellite methods from 1985–2009 Thermal adaptation and phenotypic plasticity in a warming world: Insights from common garden experiments on Alaskan sockeye salmon Association between geomorphic attributes of watersheds, water temperature, and salmon spawn timing in Alaskan streams Riding the crimson tide: mobile terrestrial consumers track phenological variation in spawning of an anadromous fish Rapid and highly variable warming of lake surface waters around the globe Watershed geomorphology and snowmelt control stream thermal sensitivity to air temperature Thermal constraints on stream consumer responses to a marine resource subsidy Subsidies of Aquatic Resources in Terrestrial Ecosystems A global database of lake surface temperatures collected by in situ and satellite methods from 1985–2009 Late glacial and Holocene fire history in the southcentral Brooks Range, Alaska; direct and indirect impacts of climatic change on fire regimes From Tundra to Forest: Ceramic Distribution and Social Interaction in Northwest Alaska Amphibians in the climate vise: loss and restoration of resilience of montane wetland ecosystems in the western US - Journal Article Describing the postglacial pattern and rate of Picea expansion in Alaska using paleoecological records