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• 11. [Article] Don Juan Pond, Antarctica: Near-surface CaCl2-brine feeding Earth’s most saline lake and implications for Mars

  To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Nature ...

  Citation × Citation Citation Abstract Copy Title: Don Juan Pond, Antarctica: Near-surface CaCl2-brine feeding Earth’s most saline lake and implications for Mars Author: Dickson, James L., Marchant, David R., Head, James W., Levy, Joseph S. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Nature Publishing Group and can be found at: http://www.nature.com/. Title: Don Juan Pond, Antarctica: Near-surface CaCl2-brine feeding Earth’s most saline lake and implications for Mars Author: Dickson, James L., Marchant, David R., Head, James W., Levy, Joseph S. To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Nature Publishing Group and can be found at: http://www.nature.com/. Close

• 12. [Article] Inventory and Mapping of Aquatic Plants at Lake Roosevelt National Recreation Area

  Lake Roosevelt is a large reservoir in northeast Washington State formed by the Grand Coulee Dam. The reservoir, which inundates portions of the Columbia River, the Spokane River, and other rivers and ...

  Citation × Citation Citation Abstract Copy Title: Inventory and Mapping of Aquatic Plants at Lake Roosevelt National Recreation Area Author: Sytsma, Mark D., Miller, Rich Year: 2008 Lake Roosevelt is a large reservoir in northeast Washington State formed by the Grand Coulee Dam. The reservoir, which inundates portions of the Columbia River, the Spokane River, and other rivers and streams, is the focus of the Lake Roosevelt National Recreation Area (LARO) that is managed by the National Park Service. LARO encompasses 100,390 acres (40,625 ha) and includes significant cultural and recreational resources. The surface area, volume, and shoreline length of Lake Roosevelt at full pool is 82,691 acres (33,490 ha), 9.41 × 1010 acre-ft (1.16 × 1010 m3) (Nigro et. al. 1981), and 630 miles (1014 km) (www.lrf.org/AboutLR/ALRFastFacts.html accessed 28 January 2008), respectively; thus, the reservoir provides a significant aquatic resource for fish and wildlife as well as recreation in the region. Invasive plants are a high-priority “vital sign” of LARO ecosystem health (Garret et. al. 2007). In recent years, LARO staff noted an increase in the density of submersed aquatic plants (macrophytes), including Myriophyllum spicatum (Eurasian watermilfoil), in the lake. M. spicatum is a highly invasive weed that forms dense surface mats that interfere with boating and angling and degrade water quality. In an effort to reduce recreational impacts of aquatic plants LARO staff established test plots of nonchemical methods of control during the drawdown period in the spring of 2007. The National Park Service contracted Portland State University Center for Lakes and Reservoirs to accomplish two main objectives: 1) document the effects of nonchemical control measures of submersed aquatic plants in the reservoir, and 2) describe the composition of the aquatic plant community at selected locations in LARO. Title: Inventory and Mapping of Aquatic Plants at Lake Roosevelt National Recreation Area Author: Sytsma, Mark D., Miller, Rich Year: 2008 Lake Roosevelt is a large reservoir in northeast Washington State formed by the Grand Coulee Dam. The reservoir, which inundates portions of the Columbia River, the Spokane River, and other rivers and streams, is the focus of the Lake Roosevelt National Recreation Area (LARO) that is managed by the National Park Service. LARO encompasses 100,390 acres (40,625 ha) and includes significant cultural and recreational resources. The surface area, volume, and shoreline length of Lake Roosevelt at full pool is 82,691 acres (33,490 ha), 9.41 × 1010 acre-ft (1.16 × 1010 m3) (Nigro et. al. 1981), and 630 miles (1014 km) (www.lrf.org/AboutLR/ALRFastFacts.html accessed 28 January 2008), respectively; thus, the reservoir provides a significant aquatic resource for fish and wildlife as well as recreation in the region. Invasive plants are a high-priority “vital sign” of LARO ecosystem health (Garret et. al. 2007). In recent years, LARO staff noted an increase in the density of submersed aquatic plants (macrophytes), including Myriophyllum spicatum (Eurasian watermilfoil), in the lake. M. spicatum is a highly invasive weed that forms dense surface mats that interfere with boating and angling and degrade water quality. In an effort to reduce recreational impacts of aquatic plants LARO staff established test plots of nonchemical methods of control during the drawdown period in the spring of 2007. The National Park Service contracted Portland State University Center for Lakes and Reservoirs to accomplish two main objectives: 1) document the effects of nonchemical control measures of submersed aquatic plants in the reservoir, and 2) describe the composition of the aquatic plant community at selected locations in LARO. Close

• 13. [Article] Biogeochemical Stoichiometry of Antarctic Dry Valley Ecosystems

  Among aquatic and terrestrial landscapes of the McMurdo Dry Valleys, Antarctica, ecosystem stoichiometry ranges from values near the Redfield ratios for C:N:P to nutrient concentrations in proportions ...

  Citation × Citation Citation Abstract Copy Title: Biogeochemical Stoichiometry of Antarctic Dry Valley Ecosystems Author: Barrett, John E., Virginia, Ross A., Lyons, W. Berry, McKnight, Diane M., Priscu, John Charles, Doran, Peter T., Fountain, Andrew G., Wall, Diana H., Moorhead, D. L. Year: 2007 Among aquatic and terrestrial landscapes of the McMurdo Dry Valleys, Antarctica, ecosystem stoichiometry ranges from values near the Redfield ratios for C:N:P to nutrient concentrations in proportions far above or below ratios necessary to support balanced microbial growth. This polar desert provides an opportunity to evaluate stoichiometric approaches to understand nutrient cycling in an ecosystem where biological diversity and activity are low, and controls over the movement and mass balances of nutrients operate over 10–10⁶ years. The simple organisms (microbial and metazoan) comprising dry valley foodwebs adhere to strict biochemical requirements in the composition of their biomass, and when activated by availability of liquid water, they influence the chemical composition of their environment according to these ratios. Nitrogen and phosphorus varied significantly in terrestrial and aquatic ecosystems occurring on landscape surfaces across a wide range of exposure ages, indicating strong influences of landscape development and geochemistry on nutrient availability. Biota control the elemental ratio of stream waters, while geochemical stoichiometry (e.g., weathering, atmospheric deposition) evidently limits the distribution of soil invertebrates. We present a conceptual model describing transformations across dry valley landscapes facilitated by exchanges of liquid water and biotic processing of dissolved nutrients. We conclude that contemporary ecosystem stoichiometry of Antarctic Dry Valley soils, glaciers, streams, and lakes results from a combination of extant biological processes superimposed on a legacy of landscape processes and previous climates. Title: Biogeochemical Stoichiometry of Antarctic Dry Valley Ecosystems Author: Barrett, John E., Virginia, Ross A., Lyons, W. Berry, McKnight, Diane M., Priscu, John Charles, Doran, Peter T., Fountain, Andrew G., Wall, Diana H., Moorhead, D. L. Year: 2007 Among aquatic and terrestrial landscapes of the McMurdo Dry Valleys, Antarctica, ecosystem stoichiometry ranges from values near the Redfield ratios for C:N:P to nutrient concentrations in proportions far above or below ratios necessary to support balanced microbial growth. This polar desert provides an opportunity to evaluate stoichiometric approaches to understand nutrient cycling in an ecosystem where biological diversity and activity are low, and controls over the movement and mass balances of nutrients operate over 10–10⁶ years. The simple organisms (microbial and metazoan) comprising dry valley foodwebs adhere to strict biochemical requirements in the composition of their biomass, and when activated by availability of liquid water, they influence the chemical composition of their environment according to these ratios. Nitrogen and phosphorus varied significantly in terrestrial and aquatic ecosystems occurring on landscape surfaces across a wide range of exposure ages, indicating strong influences of landscape development and geochemistry on nutrient availability. Biota control the elemental ratio of stream waters, while geochemical stoichiometry (e.g., weathering, atmospheric deposition) evidently limits the distribution of soil invertebrates. We present a conceptual model describing transformations across dry valley landscapes facilitated by exchanges of liquid water and biotic processing of dissolved nutrients. We conclude that contemporary ecosystem stoichiometry of Antarctic Dry Valley soils, glaciers, streams, and lakes results from a combination of extant biological processes superimposed on a legacy of landscape processes and previous climates. Close

• 14. [Article] Hyperspectral Measurements of Wet, Dry and Saline Soils from the McMurdo Dry Valleys: Soil Moisture Properties from Remote Sensing

  Soil moisture is a spatially heterogeneous quantity in the McMurdo Dry Valleys of Antarctica that exerts a large influence on the biological community and on the thermal state of Dry Valleys permafrost. ...

  Citation × Citation Citation Abstract Copy Title: Hyperspectral Measurements of Wet, Dry and Saline Soils from the McMurdo Dry Valleys: Soil Moisture Properties from Remote Sensing Author: Levy, Joseph S., Nolin, Anne, Fountain, Andrew G., Head, James W. Year: 2014 Soil moisture is a spatially heterogeneous quantity in the McMurdo Dry Valleys of Antarctica that exerts a large influence on the biological community and on the thermal state of Dry Valleys permafrost. The goal of this project was to determine whether hyperspectral remote sensing techniques could be used to determine soil moisture conditions in the Dry Valleys. We measured the spectral reflectance factors of wetted soil samples from the Dry Valleys under natural light conditions and related diagnostic spectral features to surface layer soil moisture content. Diagnostic water absorption features in the spectra at 1.4 mu m and 1.9 mu m were present in all samples, including samples doped with high concentrations of chloride salts. The depth of the 1.4 mu m absorption is shown to increase linearly with increasing gravimetric water content. These results suggest that airborne hyperspectral imaging of the Dry Valleys could generate soil moisture maps of this environment over large spatial areas using non-invasive remote-sensing techniques. Title: Hyperspectral Measurements of Wet, Dry and Saline Soils from the McMurdo Dry Valleys: Soil Moisture Properties from Remote Sensing Author: Levy, Joseph S., Nolin, Anne, Fountain, Andrew G., Head, James W. Year: 2014 Soil moisture is a spatially heterogeneous quantity in the McMurdo Dry Valleys of Antarctica that exerts a large influence on the biological community and on the thermal state of Dry Valleys permafrost. The goal of this project was to determine whether hyperspectral remote sensing techniques could be used to determine soil moisture conditions in the Dry Valleys. We measured the spectral reflectance factors of wetted soil samples from the Dry Valleys under natural light conditions and related diagnostic spectral features to surface layer soil moisture content. Diagnostic water absorption features in the spectra at 1.4 mu m and 1.9 mu m were present in all samples, including samples doped with high concentrations of chloride salts. The depth of the 1.4 mu m absorption is shown to increase linearly with increasing gravimetric water content. These results suggest that airborne hyperspectral imaging of the Dry Valleys could generate soil moisture maps of this environment over large spatial areas using non-invasive remote-sensing techniques. Close

• 15. [Article] Glacial Ecosystems

  There is now compelling evidence that microbially mediated reactions impart a significant effect upon the dynamics, composition, and abundance of nutrients in glacial melt water. Consequently, we must ...

  Citation × Citation Citation Abstract Copy Title: Glacial Ecosystems Author: Hodson, Amy, Anesio, Alexandre M., Tranter, Martyn, Fountain, Andrew G., Osborn, Mark, Priscu, John Charles, Laybourn-Perry, Johanna, Sattler, Birgit Year: 2008 There is now compelling evidence that microbially mediated reactions impart a significant effect upon the dynamics, composition, and abundance of nutrients in glacial melt water. Consequently, we must now consider ice masses as ecosystem habitats in their own right and address their diversity, functional potential, and activity as part of alpine and polar environments. Although such research is already underway, its fragmentary nature provides little basis for developing modern concepts of glacier ecology. This paper therefore provides a much-needed framework for development by reviewing the physical, biogeochemical, and microbiological characteristics of microbial habitats that have been identified within glaciers and ice sheets. Two key glacial ecosystems emerge, one inhabiting the glacier surface (the supraglacial ecosystem) and one at the ice-bed interface (the subglacial ecosystem). The supraglacial ecosystem is characterized by a diverse consortium of microbes (usually bacteria, algae, phytoflagellates, fungi, viruses and occasional rotifers, tardigrades, and diatoms) within the snowpack, supraglacial streams, and melt pools (cryoconite holes). The subglacial system is dominated by aerobic/anaerobic bacteria and most probably viruses in basal ice/till mixtures and subglacial lakes. A third, so-called englacial ecosystem is also described, but it is demonstrated that conditions within glacier ice are sufficient to make metabolic activity and its impact upon nutrient dynamics negligible at the glacier scale. Consideration of the surface and internal heat balances of the glacier show that all glacial ecosystems are sensitive to climate change, although at different timescales. Thus, while rapid, melt-driven habitat changes lead to melt-out, resuscitation, and redistribution of microorganisms in many supraglacial ecosystems, much slower climatic and glacial mass-balance processes effect such changes in the subglacial ecosystem. Paradoxically, it is shown that these forces have brought about net refreezing and the onset of cryostasis in the subglacial ecosystems of many Arctic glaciers subject to thinning in recent decades. Title: Glacial Ecosystems Author: Hodson, Amy, Anesio, Alexandre M., Tranter, Martyn, Fountain, Andrew G., Osborn, Mark, Priscu, John Charles, Laybourn-Perry, Johanna, Sattler, Birgit Year: 2008 There is now compelling evidence that microbially mediated reactions impart a significant effect upon the dynamics, composition, and abundance of nutrients in glacial melt water. Consequently, we must now consider ice masses as ecosystem habitats in their own right and address their diversity, functional potential, and activity as part of alpine and polar environments. Although such research is already underway, its fragmentary nature provides little basis for developing modern concepts of glacier ecology. This paper therefore provides a much-needed framework for development by reviewing the physical, biogeochemical, and microbiological characteristics of microbial habitats that have been identified within glaciers and ice sheets. Two key glacial ecosystems emerge, one inhabiting the glacier surface (the supraglacial ecosystem) and one at the ice-bed interface (the subglacial ecosystem). The supraglacial ecosystem is characterized by a diverse consortium of microbes (usually bacteria, algae, phytoflagellates, fungi, viruses and occasional rotifers, tardigrades, and diatoms) within the snowpack, supraglacial streams, and melt pools (cryoconite holes). The subglacial system is dominated by aerobic/anaerobic bacteria and most probably viruses in basal ice/till mixtures and subglacial lakes. A third, so-called englacial ecosystem is also described, but it is demonstrated that conditions within glacier ice are sufficient to make metabolic activity and its impact upon nutrient dynamics negligible at the glacier scale. Consideration of the surface and internal heat balances of the glacier show that all glacial ecosystems are sensitive to climate change, although at different timescales. Thus, while rapid, melt-driven habitat changes lead to melt-out, resuscitation, and redistribution of microorganisms in many supraglacial ecosystems, much slower climatic and glacial mass-balance processes effect such changes in the subglacial ecosystem. Paradoxically, it is shown that these forces have brought about net refreezing and the onset of cryostasis in the subglacial ecosystems of many Arctic glaciers subject to thinning in recent decades. Close

• 16. [Article] Introduction to Common Native and Potential Invasive Freshwater Plants in Alaska

  Freshwater aquatic plants are found in most lakes and rivers in Alaska. They range from tiny floating plants that can form mats on a lake surface to emergent plants growing two meters above the water. ...

  Citation × Citation Citation Abstract Copy Title: Introduction to Common Native and Potential Invasive Freshwater Plants in Alaska Author: Morgan, Vanessa Howard, Sytsma, Mark Year: 2009 Freshwater aquatic plants are found in most lakes and rivers in Alaska. They range from tiny floating plants that can form mats on a lake surface to emergent plants growing two meters above the water. Aquatic plants are an important part of freshwater environments. They provide food and shelter for a wide variety of insects, fish, mammals, and birds; stabilize shorelines; and form an important link in nutrient cycles. To date, Alaska has had relatively few problems with invasive, non-native aquatic plants. However, invasive aquatic plants pose an increasing threat to human safety and the integrity of native aquatic communities. Actions taken to detect and prevent the introduction and spread of invasive aquatic plants in Alaska are necessary in order to avoid the environmental and economic harm invasive plants have caused in other parts of the United States. The primary purposes of this manual are to aide the identification of freshwater aquatic plants that are likely to be seen in Alaska’s lakes, streams, bogs and marshes; and to help prevent the spread of harmful invasive plants. This manual was written for people who do not necessarily have a scientific background, but it also should be useful for professionals who need assistance in identifying common aquatic species. Title: Introduction to Common Native and Potential Invasive Freshwater Plants in Alaska Author: Morgan, Vanessa Howard, Sytsma, Mark Year: 2009 Freshwater aquatic plants are found in most lakes and rivers in Alaska. They range from tiny floating plants that can form mats on a lake surface to emergent plants growing two meters above the water. Aquatic plants are an important part of freshwater environments. They provide food and shelter for a wide variety of insects, fish, mammals, and birds; stabilize shorelines; and form an important link in nutrient cycles. To date, Alaska has had relatively few problems with invasive, non-native aquatic plants. However, invasive aquatic plants pose an increasing threat to human safety and the integrity of native aquatic communities. Actions taken to detect and prevent the introduction and spread of invasive aquatic plants in Alaska are necessary in order to avoid the environmental and economic harm invasive plants have caused in other parts of the United States. The primary purposes of this manual are to aide the identification of freshwater aquatic plants that are likely to be seen in Alaska’s lakes, streams, bogs and marshes; and to help prevent the spread of harmful invasive plants. This manual was written for people who do not necessarily have a scientific background, but it also should be useful for professionals who need assistance in identifying common aquatic species. Close

• 17. [Article] Recreational Boats as Potential Vectors of Marine Organisms at an Invasion Hotspot

  With more than 200 aquatic nonindigenous species (NIS), San Francisco Bay (California, USA) is among the world’s most invaded harbors. Hard-substratum benthic (biofouling) organisms, which dominate NIS ...

  Citation × Citation Citation Abstract Copy Title: Recreational Boats as Potential Vectors of Marine Organisms at an Invasion Hotspot Author: Davidson, Ian C., Zabin, Chela J., Chang, Andrew L., Brown, Christopher W., Sytsma, Mark, Ruiz, Gregory M. Year: 2010 With more than 200 aquatic nonindigenous species (NIS), San Francisco Bay (California, USA) is among the world’s most invaded harbors. Hard-substratum benthic (biofouling) organisms, which dominate NIS richness, have arrived primarily as a result of shipping and aquaculture activity over past centuries. To date there has been no assessment of the leisure craft vector in the Bay. We aimed to characterize (1) biofouling on boats’ submerged surfaces and (2) boater behavior likely to affect the risk of NIS transfers. We used an underwater pole-cam, specimen collections, and a boater questionnaire to quantify the extent and composition of biofouling on recreational boats and to evaluate boater behavior at a subset of the Bay’s marinas. Several NIS, already established within the Bay, were recorded from vessel hulls, including the bryozoans Bugula neritina, Membranipora chesapeakensis and Watersipora sp., the ascidians Botrylloides violaceus, Styela clava and Ciona intestinalis, the polychaete Ficopomatus enigmaticus, and the sponge Clathria prolifera. Only 16% of questionnaire respondents had traveled to sites outside the Bay in the previous 12 mo. Frequency of hull painting and cleaning varied substantially, but we did not find strong patterns of biofouling extent associated with hull husbandry or boat usage. The potential for within-Bay and coastwise regional spread of NIS is high, and recreational boats probably interact in close proximity to other vectors (e.g. commercial ships), causing a ratchet effect of vector events; however, there remains a gap in understanding the levels and condition of biofouling on transient boats. Transient vessels from San Francisco Bay and other West Coast sites should be the focus of future studies to evaluate the extent to which organisms are being transferred among bays and how vector management could be applied to prevent NIS transfers and impacts. Title: Recreational Boats as Potential Vectors of Marine Organisms at an Invasion Hotspot Author: Davidson, Ian C., Zabin, Chela J., Chang, Andrew L., Brown, Christopher W., Sytsma, Mark, Ruiz, Gregory M. Year: 2010 With more than 200 aquatic nonindigenous species (NIS), San Francisco Bay (California, USA) is among the world’s most invaded harbors. Hard-substratum benthic (biofouling) organisms, which dominate NIS richness, have arrived primarily as a result of shipping and aquaculture activity over past centuries. To date there has been no assessment of the leisure craft vector in the Bay. We aimed to characterize (1) biofouling on boats’ submerged surfaces and (2) boater behavior likely to affect the risk of NIS transfers. We used an underwater pole-cam, specimen collections, and a boater questionnaire to quantify the extent and composition of biofouling on recreational boats and to evaluate boater behavior at a subset of the Bay’s marinas. Several NIS, already established within the Bay, were recorded from vessel hulls, including the bryozoans Bugula neritina, Membranipora chesapeakensis and Watersipora sp., the ascidians Botrylloides violaceus, Styela clava and Ciona intestinalis, the polychaete Ficopomatus enigmaticus, and the sponge Clathria prolifera. Only 16% of questionnaire respondents had traveled to sites outside the Bay in the previous 12 mo. Frequency of hull painting and cleaning varied substantially, but we did not find strong patterns of biofouling extent associated with hull husbandry or boat usage. The potential for within-Bay and coastwise regional spread of NIS is high, and recreational boats probably interact in close proximity to other vectors (e.g. commercial ships), causing a ratchet effect of vector events; however, there remains a gap in understanding the levels and condition of biofouling on transient boats. Transient vessels from San Francisco Bay and other West Coast sites should be the focus of future studies to evaluate the extent to which organisms are being transferred among bays and how vector management could be applied to prevent NIS transfers and impacts. Close