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• 1. [Article] Modeling coastal landscape dynamics

  Examines methods used to predict the way ecological systems respond to human modifications. Coastal marshes; Process-based dynamic spatial ecosystem simulation models; Coastal ecological landscape spatial ...

  Citation × Citation Citation Abstract Copy Title: Modeling coastal landscape dynamics Author: Costanza, Robert, Sklar, Fred Hal, White, Mary L. Year: 1990 Examines methods used to predict the way ecological systems respond to human modifications. Coastal marshes; Process-based dynamic spatial ecosystem simulation models; Coastal ecological landscape spatial simulation model; Scenario analysis. Title: Modeling coastal landscape dynamics Author: Costanza, Robert, Sklar, Fred Hal, White, Mary L. Year: 1990 Examines methods used to predict the way ecological systems respond to human modifications. Coastal marshes; Process-based dynamic spatial ecosystem simulation models; Coastal ecological landscape spatial simulation model; Scenario analysis. Close

• 2. [Article] Emerging Contaminants in Oregon Coastal Waters: Hotspots, Landscape Drivers and Synergistic Effects on Bivalves

  This presentation focuses on the following research questions: Types and levels of contaminants of emerging concern (CECs) in Oregon’s coastal ocean? Levels of CECs in native and commercial oysters? ...

  Citation × Citation Citation Abstract Copy Title: Emerging Contaminants in Oregon Coastal Waters: Hotspots, Landscape Drivers and Synergistic Effects on Bivalves Author: Granek, Elise F., Fish, William, Strecker, Angela L. Year: 2013 This presentation focuses on the following research questions: Types and levels of contaminants of emerging concern (CECs) in Oregon’s coastal ocean? Levels of CECs in native and commercial oysters? Ecological effects (growth, reproductive output, etc.) of these contaminants in marine bivalves? Title: Emerging Contaminants in Oregon Coastal Waters: Hotspots, Landscape Drivers and Synergistic Effects on Bivalves Author: Granek, Elise F., Fish, William, Strecker, Angela L. Year: 2013 This presentation focuses on the following research questions: Types and levels of contaminants of emerging concern (CECs) in Oregon’s coastal ocean? Levels of CECs in native and commercial oysters? Ecological effects (growth, reproductive output, etc.) of these contaminants in marine bivalves? Close

• 3. [Article] Demography and the Evolution of Logistic Organization on the Northern Northwest Coast Between 11,000 and 5,000 cal BP

  Focusing on the relationship between demography and sedentary behavior, this thesis explores changes to mobility strategies on the Northern Northwest Coast of North America between 11,000 and 5,000 cal ...

  Citation × Citation Citation Abstract Copy Title: Demography and the Evolution of Logistic Organization on the Northern Northwest Coast Between 11,000 and 5,000 cal BP Author: Brown, Thomas Jay Year: 2016 Focusing on the relationship between demography and sedentary behavior, this thesis explores changes to mobility strategies on the Northern Northwest Coast of North America between 11,000 and 5,000 cal BP. Drawing on a regional database of radiocarbon dates, it uses summed probability distributions (SPDs) of calibrated dates as a proxy for population change, in combination with syntheses of previously published technological, paleo environmental and settlement pattern data to test three hypotheses derived from the literature about the development of logistic mobility among maritime hunter-gatherers on the Northern Coast. In all, each of the hypotheses proposes that early peoples on the coast were foragers that utilized high levels of residential mobility, who later adopted collector (logistic) strategies. Two of the hypotheses emphasize the role of population growth and/or packing and resource distribution in this transformation, while the third emphasizes population replacement. Other issues addressed within this thesis are whether or not the forager-collector continuum, as it is used for terrestrial hunter-gatherers, can be applied to those in aquatic settings. Also explored, is the question of whether the available data is sufficient for making and/or testing claims about early mobility patterns in the region. The results of the demographic models suggest that while population levels were volatile, volatility declined through time and that there is no significant trend in either growth or decline of overall population levels throughout the region. This thesis also confirmed that significant changes to mobility, as evidenced by the emergence of semi-sedentary to sedentary living, begin to appear by ~7,000 cal BP. However, there appears to be little, if any correlation between the advent of more sedentary and logistic behavior and any of the variables tested here. Thus this author suggests, in agreement with Ames (1985; 2004) and Binford (2001) that the distribution of resources and labor organization needs within aquatic environments are sufficient without any other drivers for the development and intensification of logistic mobility. The principle analytic contribution of this research comes from the demographic modeling that relied on the construction of summed probability distributions. Though these methods have become commonplace in other settings (namely Europe), this thesis presents the first application of these methods within the time period and region covered. Moreover, this research is one of the only of its kind to address demographic histories within coastal landscapes that utilizes both marine and terrestrial 14C samples. In order to explore possible biases within the database, comparisons of marine and terrestrial SPDs were made between sub-sections of the region (i.e. Haida Gwaii, Southeast Alaska and the Dundas Islands). Though patterning between each of these areas was consistent, these comparative methods revealed an unexpected finding; a massive population crash throughout the region that began between ~9,000-8,800 cal BP and lasted till around 8,400 cal BP. Importantly, this crash was witnessed within all of the individual sub-areas and within SPDs made from both the marine and terrestrial 14C samples, though the reasons behind this collapse and verification of its existence require future research. However, finding this collapse at all further highlighted the need for use of correctly calibrated 14C dates, as the gap in 14C dates effectively disappears when using uncalibrated dates, which has been a longstanding tradition within Northwest archaeology. Title: Demography and the Evolution of Logistic Organization on the Northern Northwest Coast Between 11,000 and 5,000 cal BP Author: Brown, Thomas Jay Year: 2016 Focusing on the relationship between demography and sedentary behavior, this thesis explores changes to mobility strategies on the Northern Northwest Coast of North America between 11,000 and 5,000 cal BP. Drawing on a regional database of radiocarbon dates, it uses summed probability distributions (SPDs) of calibrated dates as a proxy for population change, in combination with syntheses of previously published technological, paleo environmental and settlement pattern data to test three hypotheses derived from the literature about the development of logistic mobility among maritime hunter-gatherers on the Northern Coast. In all, each of the hypotheses proposes that early peoples on the coast were foragers that utilized high levels of residential mobility, who later adopted collector (logistic) strategies. Two of the hypotheses emphasize the role of population growth and/or packing and resource distribution in this transformation, while the third emphasizes population replacement. Other issues addressed within this thesis are whether or not the forager-collector continuum, as it is used for terrestrial hunter-gatherers, can be applied to those in aquatic settings. Also explored, is the question of whether the available data is sufficient for making and/or testing claims about early mobility patterns in the region. The results of the demographic models suggest that while population levels were volatile, volatility declined through time and that there is no significant trend in either growth or decline of overall population levels throughout the region. This thesis also confirmed that significant changes to mobility, as evidenced by the emergence of semi-sedentary to sedentary living, begin to appear by ~7,000 cal BP. However, there appears to be little, if any correlation between the advent of more sedentary and logistic behavior and any of the variables tested here. Thus this author suggests, in agreement with Ames (1985; 2004) and Binford (2001) that the distribution of resources and labor organization needs within aquatic environments are sufficient without any other drivers for the development and intensification of logistic mobility. The principle analytic contribution of this research comes from the demographic modeling that relied on the construction of summed probability distributions. Though these methods have become commonplace in other settings (namely Europe), this thesis presents the first application of these methods within the time period and region covered. Moreover, this research is one of the only of its kind to address demographic histories within coastal landscapes that utilizes both marine and terrestrial 14C samples. In order to explore possible biases within the database, comparisons of marine and terrestrial SPDs were made between sub-sections of the region (i.e. Haida Gwaii, Southeast Alaska and the Dundas Islands). Though patterning between each of these areas was consistent, these comparative methods revealed an unexpected finding; a massive population crash throughout the region that began between ~9,000-8,800 cal BP and lasted till around 8,400 cal BP. Importantly, this crash was witnessed within all of the individual sub-areas and within SPDs made from both the marine and terrestrial 14C samples, though the reasons behind this collapse and verification of its existence require future research. However, finding this collapse at all further highlighted the need for use of correctly calibrated 14C dates, as the gap in 14C dates effectively disappears when using uncalibrated dates, which has been a longstanding tradition within Northwest archaeology. Close

• 4. [Article] Channel Shallowing as Mitigation of Coastal Flooding

  Here, we demonstrate that reductions in the depth of inlets or estuary channels can be used to reduce or prevent coastal flooding. A validated hydrodynamic model of Jamaica Bay, New York City (NYC), is ...

  Citation × Citation Citation Abstract Copy Title: Channel Shallowing as Mitigation of Coastal Flooding Author: Orton, Philip M., Talke, Stefan A., Jay, David A., Yin, Larry, Blumberg, Alan F., Georgas, Nickitas, Zhao, Haihong, Roberts, Hugh J., MacManus, Kytt Year: 2015 Here, we demonstrate that reductions in the depth of inlets or estuary channels can be used to reduce or prevent coastal flooding. A validated hydrodynamic model of Jamaica Bay, New York City (NYC), is used to test nature-based adaptation measures in ameliorating flooding for NYC’s two largest historical coastal flood events. In addition to control runs with modern bathymetry, three altered landscape scenarios are tested: (1) increasing the area of wetlands to their 1879 footprint and bathymetry, but leaving deep shipping channels unaltered; (2) shallowing all areas deeper than 2 m in the bay to be 2 m below Mean Low Water; (3) shallowing only the narrowest part of the inlet to the bay. These three scenarios are deliberately extreme and designed to evaluate the leverage each approach exerts on water levels. They result in peak water level reductions of 0.3%, 15%, and 6.8% for Hurricane Sandy, and 2.4%, 46% and 30% for the Category-3 hurricane of 1821, respectively (bay-wide averages). These results suggest that shallowing can provide greater flood protection than wetland restoration, and it is particularly effective at reducing "fast-pulse" storm surges that rise and fall quickly over several hours, like that of the 1821 storm. Nonetheless, the goal of flood mitigation must be weighed against economic, navigation, and ecological needs, and practical concerns such as the availability of sediment. Title: Channel Shallowing as Mitigation of Coastal Flooding Author: Orton, Philip M., Talke, Stefan A., Jay, David A., Yin, Larry, Blumberg, Alan F., Georgas, Nickitas, Zhao, Haihong, Roberts, Hugh J., MacManus, Kytt Year: 2015 Here, we demonstrate that reductions in the depth of inlets or estuary channels can be used to reduce or prevent coastal flooding. A validated hydrodynamic model of Jamaica Bay, New York City (NYC), is used to test nature-based adaptation measures in ameliorating flooding for NYC’s two largest historical coastal flood events. In addition to control runs with modern bathymetry, three altered landscape scenarios are tested: (1) increasing the area of wetlands to their 1879 footprint and bathymetry, but leaving deep shipping channels unaltered; (2) shallowing all areas deeper than 2 m in the bay to be 2 m below Mean Low Water; (3) shallowing only the narrowest part of the inlet to the bay. These three scenarios are deliberately extreme and designed to evaluate the leverage each approach exerts on water levels. They result in peak water level reductions of 0.3%, 15%, and 6.8% for Hurricane Sandy, and 2.4%, 46% and 30% for the Category-3 hurricane of 1821, respectively (bay-wide averages). These results suggest that shallowing can provide greater flood protection than wetland restoration, and it is particularly effective at reducing "fast-pulse" storm surges that rise and fall quickly over several hours, like that of the 1821 storm. Nonetheless, the goal of flood mitigation must be weighed against economic, navigation, and ecological needs, and practical concerns such as the availability of sediment. Close

• 5. [Article] “Up On the Mountain”: Ethnobotanical Importance of Montane Sites In Pacific Coastal North America

  The Pacific Coastal Mountains of western North America have immense ethnobotanical significance. Since time immemorial, Indigenous Peoples have journeyed from permanent settlements in lowland regions to ...

  Citation × Citation Citation Abstract Copy Title: “Up On the Mountain”: Ethnobotanical Importance of Montane Sites In Pacific Coastal North America Author: Turner, Nancy J., Deur, Douglas, Mellott, Carla Rae Year: 2011 The Pacific Coastal Mountains of western North America have immense ethnobotanical significance. Since time immemorial, Indigenous Peoples have journeyed from permanent settlements in lowland regions to upland sites in order to harvest and process a range of plant resources –foods, materials and medicines– as well as to hunt and fish, and undertake spiritual activities. Two culturally significant montane areas, widely separated geographically, are described as case examples: pt-e´n’i (Botanie Valley) in Nlaka’pmx territory of southern interior British Columbia, famous for its abundance of edible root resources; and iwamkani, an iconic huckleberry picking location for the Klamath in southern Oregon. Patterns of montane use are notably consistent throughout the region. Indigenous People intentionally modified montane landscapes through fire and other means to enhance resource productivity and predictability. In turn, mountain environments and resources have significantly influenced Indigenous Peoples’ lifeways and knowledge systems. The integrity of montane biocultural systems has been threatened by industrial development, fire suppression and, most recently, the changing global climate. Yet, montane areas remain as key elements of biocultural heritage and must be protected for continued social-ecological health and well-being of Indigenous Peoples. Title: “Up On the Mountain”: Ethnobotanical Importance of Montane Sites In Pacific Coastal North America Author: Turner, Nancy J., Deur, Douglas, Mellott, Carla Rae Year: 2011 The Pacific Coastal Mountains of western North America have immense ethnobotanical significance. Since time immemorial, Indigenous Peoples have journeyed from permanent settlements in lowland regions to upland sites in order to harvest and process a range of plant resources –foods, materials and medicines– as well as to hunt and fish, and undertake spiritual activities. Two culturally significant montane areas, widely separated geographically, are described as case examples: pt-e´n’i (Botanie Valley) in Nlaka’pmx territory of southern interior British Columbia, famous for its abundance of edible root resources; and iwamkani, an iconic huckleberry picking location for the Klamath in southern Oregon. Patterns of montane use are notably consistent throughout the region. Indigenous People intentionally modified montane landscapes through fire and other means to enhance resource productivity and predictability. In turn, mountain environments and resources have significantly influenced Indigenous Peoples’ lifeways and knowledge systems. The integrity of montane biocultural systems has been threatened by industrial development, fire suppression and, most recently, the changing global climate. Yet, montane areas remain as key elements of biocultural heritage and must be protected for continued social-ecological health and well-being of Indigenous Peoples. Close

• 6. [Article] Linking Ecology and Economics for Ecosystem Management

  This article outlines an approach, based on ecosystem services, for assessing the trade-offs inherent in managing humans embedded in ecological systems. Evaluating these trade-offs requires an understanding ...

  Citation × Citation Citation Abstract Copy Title: Linking Ecology and Economics for Ecosystem Management Author: Farber, Stephen, Costanza, Robert, Childers, Daniel L., Erickson, Jon, Gross, Katherine, Grove, Morgan, Hopkinson, Charles S., Kahn, James, Pincetl, Stephanie, Troy, Austin, Warren, Paige, Wilson, Matthew Year: 2006 This article outlines an approach, based on ecosystem services, for assessing the trade-offs inherent in managing humans embedded in ecological systems. Evaluating these trade-offs requires an understanding of the biophysical magnitudes of the changes in ecosystem services that result from human actions, and of the impact of these changes on human welfare.We summarize the state of the art of ecosystem services?based management and the information needs for applying it. Three case studies of Long Term Ecological Research (LTER) sites?coastal, urban, and agricultural? illustrate the usefulness, information needs, quantification possibilities, and methods for this approach. One example of the application of this approach, with rigorously established service changes and valuations taken from the literature, is used to illustrate the potential for full economic valuation of several agricultural landscape management options, including managing for water quality, biodiversity, and crop productivity. Title: Linking Ecology and Economics for Ecosystem Management Author: Farber, Stephen, Costanza, Robert, Childers, Daniel L., Erickson, Jon, Gross, Katherine, Grove, Morgan, Hopkinson, Charles S., Kahn, James, Pincetl, Stephanie, Troy, Austin, Warren, Paige, Wilson, Matthew Year: 2006 This article outlines an approach, based on ecosystem services, for assessing the trade-offs inherent in managing humans embedded in ecological systems. Evaluating these trade-offs requires an understanding of the biophysical magnitudes of the changes in ecosystem services that result from human actions, and of the impact of these changes on human welfare.We summarize the state of the art of ecosystem services?based management and the information needs for applying it. Three case studies of Long Term Ecological Research (LTER) sites?coastal, urban, and agricultural? illustrate the usefulness, information needs, quantification possibilities, and methods for this approach. One example of the application of this approach, with rigorously established service changes and valuations taken from the literature, is used to illustrate the potential for full economic valuation of several agricultural landscape management options, including managing for water quality, biodiversity, and crop productivity. Close

• 7. [Article] Oregon Natural Areas Plan

  The rich diversity of ecosystems and native plants and animals is one of Oregon's most distinctive and valued qualities. Our state contains rain forests, dry forests, oak woodlands, alpine meadows, prairies, ...

  Citation × Citation Citation Abstract Copy Title: Oregon Natural Areas Plan Author: Oregon Natural Heritage Advisory Council Year: 2010 The rich diversity of ecosystems and native plants and animals is one of Oregon's most distinctive and valued qualities. Our state contains rain forests, dry forests, oak woodlands, alpine meadows, prairies, deserts, marshes, estuaries, dunes, rocky headlands, lakes and streams. There are a number of reasons it is so diverse. First are the extremes of climate, with rainfall ranging from over 200 inches a year along Oregon’s north coast, to less than 7 inches a year in the Alvord Desert, and temperatures from the very mild banana belt along the coast near the California border to the extremes of the high alpine areas of the Wallowa Mountains. Secondly, Oregon is diverse geographically and geologically, having ancient serpentine landscapes in the Siskiyou Mountains and recent volcanics in the Cascades and the deepest gorge in North America at Hells Canyon. Lastly, Oregon is a floristic crossroads, with arctic boreal species finding their southern limit, Rocky Mountain species common in northeastern Oregon, Great Basin species in southeastern Oregon, and California coastal and Sierra species in the southwest, all mixing with native northwestern taxa to create a wide array of habitats. Title: Oregon Natural Areas Plan Author: Oregon Natural Heritage Advisory Council Year: 2010 The rich diversity of ecosystems and native plants and animals is one of Oregon's most distinctive and valued qualities. Our state contains rain forests, dry forests, oak woodlands, alpine meadows, prairies, deserts, marshes, estuaries, dunes, rocky headlands, lakes and streams. There are a number of reasons it is so diverse. First are the extremes of climate, with rainfall ranging from over 200 inches a year along Oregon’s north coast, to less than 7 inches a year in the Alvord Desert, and temperatures from the very mild banana belt along the coast near the California border to the extremes of the high alpine areas of the Wallowa Mountains. Secondly, Oregon is diverse geographically and geologically, having ancient serpentine landscapes in the Siskiyou Mountains and recent volcanics in the Cascades and the deepest gorge in North America at Hells Canyon. Lastly, Oregon is a floristic crossroads, with arctic boreal species finding their southern limit, Rocky Mountain species common in northeastern Oregon, Great Basin species in southeastern Oregon, and California coastal and Sierra species in the southwest, all mixing with native northwestern taxa to create a wide array of habitats. Close

• 8. [Article] A Morphologic Proxy for Debris Flow Erosion With Application to the Earthquake Deformation Cycle, Cascadia Subduction Zone, USA

  In unglaciated steeplands, valley reaches dominated by debris flow scour and incision set landscape form as they often account for > 80% of valley network length and relief. While hillslope and fluvial ...

  Citation × Citation Citation Abstract Copy Title: A Morphologic Proxy for Debris Flow Erosion With Application to the Earthquake Deformation Cycle, Cascadia Subduction Zone, USA Author: Penserini, Brian D., Roering, Joshua J., Strieg, Ashley Year: 2017 In unglaciated steeplands, valley reaches dominated by debris flow scour and incision set landscape form as they often account for > 80% of valley network length and relief. While hillslope and fluvial process models have frequently been combined with digital topography to develop morphologic proxies for erosion rate and drainage divide migration, debris-flow-dominated networks, despite their ubiquity, have not been exploited for this purpose. Here, we applied an empirical function that describes how slope-area data systematically deviate from so-called fluvial power-law behavior at small drainage areas. Using airborne LiDAR data for 83 small (~ 1 km2) catchments in the western Oregon Coast Range, we quantified variation in model parameters and observed that the curvature of the power-law scaling deviation varies with catchment-averaged erosion rate estimated from cosmogenic nuclides in stream sediments. Given consistent climate and lithology across our study area and assuming steady erosion, we used this calibrated denudation-morphology relationship to map spatial patterns of long-term uplift for our study catchments. By combining our predicted pattern of long-term uplift rate with paleoseismic and geodetic (tide gauge, GPS, and leveling) data, we estimated the spatial distribution of coseismic subsidence experienced during megathrust earthquakes along the Cascadia Subduction Zone. Our estimates of coseismic subsidence near the coast (0.4 to 0.7 m for earthquake recurrence intervals of 300 to 500 years) agree with field measurements from numerous stratigraphic studies. Our results also demonstrate that coseismic subsidence decreases inland to negligible values > 25 km from the coast, reflecting the diminishing influence of the earthquake deformation cycle on vertical changes of the interior coastal ranges. More generally, our results demonstrate that debris flow valley networks serve as highly localized, yet broadly distributed indicators of erosion (and rock uplift), making them invaluable for mapping crustal deformation and landscape adjustment. © 2017 Elsevier B.V. Title: A Morphologic Proxy for Debris Flow Erosion With Application to the Earthquake Deformation Cycle, Cascadia Subduction Zone, USA Author: Penserini, Brian D., Roering, Joshua J., Strieg, Ashley Year: 2017 In unglaciated steeplands, valley reaches dominated by debris flow scour and incision set landscape form as they often account for > 80% of valley network length and relief. While hillslope and fluvial process models have frequently been combined with digital topography to develop morphologic proxies for erosion rate and drainage divide migration, debris-flow-dominated networks, despite their ubiquity, have not been exploited for this purpose. Here, we applied an empirical function that describes how slope-area data systematically deviate from so-called fluvial power-law behavior at small drainage areas. Using airborne LiDAR data for 83 small (~ 1 km2) catchments in the western Oregon Coast Range, we quantified variation in model parameters and observed that the curvature of the power-law scaling deviation varies with catchment-averaged erosion rate estimated from cosmogenic nuclides in stream sediments. Given consistent climate and lithology across our study area and assuming steady erosion, we used this calibrated denudation-morphology relationship to map spatial patterns of long-term uplift for our study catchments. By combining our predicted pattern of long-term uplift rate with paleoseismic and geodetic (tide gauge, GPS, and leveling) data, we estimated the spatial distribution of coseismic subsidence experienced during megathrust earthquakes along the Cascadia Subduction Zone. Our estimates of coseismic subsidence near the coast (0.4 to 0.7 m for earthquake recurrence intervals of 300 to 500 years) agree with field measurements from numerous stratigraphic studies. Our results also demonstrate that coseismic subsidence decreases inland to negligible values > 25 km from the coast, reflecting the diminishing influence of the earthquake deformation cycle on vertical changes of the interior coastal ranges. More generally, our results demonstrate that debris flow valley networks serve as highly localized, yet broadly distributed indicators of erosion (and rock uplift), making them invaluable for mapping crustal deformation and landscape adjustment. © 2017 Elsevier B.V. Close

• 9. [Article] Impacts of Permafrost Degradation on a Stream in Taylor Valley, Antarctica

  The McMurdo Dry Valleys (MDV) of Antarctica are an ice-free landscape that supports a complex, microbially dominated ecosystem despite a severely arid, cold environment (< 5 cm water equivalent/y, − 18 ...

  Citation × Citation Citation Abstract Copy Title: Impacts of Permafrost Degradation on a Stream in Taylor Valley, Antarctica Author: Sudman, Zachary, Gooseff, Michael N., Fountain, Andrew G., Levy, Joseph S. Year: 2017 The McMurdo Dry Valleys (MDV) of Antarctica are an ice-free landscape that supports a complex, microbially dominated ecosystem despite a severely arid, cold environment (< 5 cm water equivalent/y, − 18 °C mean annual air temperature). Recent observations of permafrost degradation in the coastal zones of the MDV suggest that this region is nearing a threshold of rapid landscape change. In 2012, substantial thermokarst development was observed along several kilometers of the west branch of Crescent Stream in Taylor Valley mostly in the form of bank failures, whereas the adjacent east branch was unaffected. The objective of this study was to quantify the changes to the stream banks of the west branch of Crescent Stream and to determine the impacts on the composition of the stream bed material. Three annually repeated terrestrial LiDAR scans were compared to determine the rates of ground surface change caused by thermokarst formation on the stream bank. The areal extent of the thermokarst was shown to be decreasing; however, the average vertical rate of retreat remained constant. Field measurements of bed materials indicated that the west branch and the reach downstream of the confluence (of east and west branches) consistently contained more fines than the unaffected east branch. This suggests that the finer bed material is a result of the thermokarst development on the west branch. These finer bed material compositions are likely to increase the mobility of the bed material, which will have implications for stream morphology, stream algal mat communities, and downstream aquatic ecosystems. Title: Impacts of Permafrost Degradation on a Stream in Taylor Valley, Antarctica Author: Sudman, Zachary, Gooseff, Michael N., Fountain, Andrew G., Levy, Joseph S. Year: 2017 The McMurdo Dry Valleys (MDV) of Antarctica are an ice-free landscape that supports a complex, microbially dominated ecosystem despite a severely arid, cold environment (< 5 cm water equivalent/y, − 18 °C mean annual air temperature). Recent observations of permafrost degradation in the coastal zones of the MDV suggest that this region is nearing a threshold of rapid landscape change. In 2012, substantial thermokarst development was observed along several kilometers of the west branch of Crescent Stream in Taylor Valley mostly in the form of bank failures, whereas the adjacent east branch was unaffected. The objective of this study was to quantify the changes to the stream banks of the west branch of Crescent Stream and to determine the impacts on the composition of the stream bed material. Three annually repeated terrestrial LiDAR scans were compared to determine the rates of ground surface change caused by thermokarst formation on the stream bank. The areal extent of the thermokarst was shown to be decreasing; however, the average vertical rate of retreat remained constant. Field measurements of bed materials indicated that the west branch and the reach downstream of the confluence (of east and west branches) consistently contained more fines than the unaffected east branch. This suggests that the finer bed material is a result of the thermokarst development on the west branch. These finer bed material compositions are likely to increase the mobility of the bed material, which will have implications for stream morphology, stream algal mat communities, and downstream aquatic ecosystems. Close