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Patrick Walsh

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The primary purpose of this project is to acquire long-term data series ontemperature of selected lakes to support management of nursery habitat of lakerearingjuvenile sockeye salmon (Oncorhynchus nerka) in relation to climatechange. We adopted protocol developed by the National Park Service (NPS) toestablish moored all-season vertical temperature monitoring arrays in eight lakesof Kodiak, Togiak, and Alaska Peninsula/Becharof National Wildlife Refuges(NWR) in summer and fall 2011. We recorded lake temperature at a resolution of0.02°C on an hourly basis at various depth strata between lake surfaces and lakebottoms. Monitoring sites were visited annually or biannially to extract data andto service monitoring equipment....
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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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This project used existing ShoreZone coastal imagery to map 719 km of shoreline in Bristol Bay, from Cape Constantine to Cape Newenham. This section of coastline is an extremely important herring spawning area and an important component of the Bristol Bay fisheries. Intertidal and nearshore vegetation, on which herring spawn, was catalogued as part of the mapping and, along with shore types, coastal substrate, and coastal biota, added to the state-wide ShoreZone dataset.‚Äč
Categories: Data; Tags: COASTAL HABITAT, COASTAL HABITAT, COASTAL LANDFORMS, COASTAL LANDFORMS, DATA DELIVERY, All tags...
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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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