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The “Hydroecology of Flowing Waters” project was initiated in 1998 with the aim to improve understanding of how stream and river corridors function naturally in ways that produce valuable ecosystem services (e.g. flood attenuation, carbon and nutrient storage and contaminant removal, habitat value for fish and wildlife, recreation). The research is increasingly focused on how aquatic ecosystem services can be better protected in the face of degradation resulting from accelerating land use and climate change. Central to the research is the investigation of interactions between physical and biological processes, e.g. how land use change affects hydraulics and channel geomorphology in ways that produce cascading...
Understanding the effects of climatic variability is important to development of water resources, mitigation of flood hazards, and interpretation of geomorphic surfaces. Climatic variability, which is characterized by temporal changes in variability of seasonal climate that spans decades or centuries, may be more important to water-resources evaluations than changes in mean climatic conditions. Changes in variability of climate has a large effect on the probability of occurrence of extreme events, such as floods or droughts. Understanding of climatic variability and its effect on the landscape is of paramount importance for estimation of flood frequency, sediment transport rates, and long-term watershed and channel...
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Maintaining the native prairie lands of the Northern Great Plains (NGP), which provide an important habitat for declining grassland species, requires anticipating the effects of increasing atmospheric carbon dioxide (CO2) concentrations and climate change on the region’s vegetation. Specifically, climate change threatens NGP grasslands by increasing the potential encroachment of native woody species into areas where they were previously only present in minor numbers. This project used a dynamic vegetation model to simulate vegetation type (grassland, shrubland, woodland, and forest) for the NGP for a range of projected future climates and relevant management scenarios. Comparing results of these simulations illustrates...
I conduct research focused on understanding the role of microorganisms on both contaminated and pristine ecosystems. I carry out this work using a polyphasic approach that combines microbiology, molecular biology, and biogeochemistry to understand microbial processes. My work specifically aims to (1) assess the impact of microorganisms on the fate of organic and inorganic contaminants; (2) to investigate the microbial role in metal cycling, e.g., iron, uranium, and manganese cycling; (3) evaluate the potential of microbial populations to contribute to energy resources, either through coal bed methane production or mitigating contaminants due to nuclear energy production or unconventional oil and gas production;...
Robin Stewart's research is focused on identifying and understanding processes influencing the fate and bioavailability of selenium and mercury in food webs across a range of aquatic environments including estuaries, rivers, lakes and reservoirs.
Human activities from climate change to waste discharges to water management are modifying ecosystems across the earth, often in ways that are not well understood. This project addresses the problem of better understanding changes in aquatic ecosystems as driven by human disturbances interacting with natural processes. More specifically, the project studies a) the mechanisms of biological and ecological response to stressors such as metal contamination, nutrient enrichment, physical habitat alteration, climate change, and introduced species, and b) the influence of species, communities, and ecosystem processes on the distribution, transport, and fate of chemical contaminants (e.g., metals, nutrients). Most studies...
To study the mechanisms, pathways, and rates of transformation of carbon and nitrogen compounds (natural and contaminant) mediated by microorganisms in aquatic habitats and identify factors controlling these transformations and to examine the effect that these transformations have upon other biogeochemical processes.
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Ongoing climate change has the potential to negatively impact Alaska’s ecosystems and the critical services that they provide. These ecosystem services include supplying food and fiber for Alaskan communities, offering opportunities for recreational, cultural, and spiritual activities, and regulating temperature and water flow (runoff, flooding, etc.). Scientists build models to better understand processes and interactions in the natural environment and to use what we know to predict what will happen in the future, so that we can plan for it. Researchers from multiple institutions and disciplines developed an Integrated Ecosystem Model (IEM) for Alaska and Northwest Canada. The model helps forecast how climate...
The objective of this research is to study and quantitatively describe the factors that influence the response of macroinvertebrates to both anthropogenic and natural environmental factors and assess the effects macroinvertebrates have on the physical, chemical, and biological quality of aquatic systems. This involves 1) studying macroinvertebrate distributions across a range of spatial and temporal scales representing a variety of environmental settings and influences, 2) identifying and measuring the effects of stressors that are macroinvertebrate-specific, 3) identifying the effects macroinvertebrates have on the physical, chemical, and biological environment, 4) developing and applying statistical models that...
The objectives are to 1) Quantify the hydrogeomorphic and ecological controls of nutrient and contaminant fluxes in wetland ecosystems; 2) Scale wetland fluxes from site to watershed scale; and 3) Identify the principals and modeling tools for managing wetland and river ecosystems. The focus will be on floodplain ecosystems, which are poorly studied due to the challenges of working in this environment and their inherent complexity.
Phytoplankton photosynthesis drives many biogeochemical and ecological processes in lakes, estuaries, and the ocean. For example, dynamic changes in pH, trace metal speciation, and concentrations of dissolved gases (oxygen, carbon dioxide, methane), inorganic nutrients (nitrate, phosphate, silicate), and organic compounds (amino acids, organosulfur compounds) are all closely associated with fluctuations in phytoplankton photosynthesis. Trophic linkages also exist, between the phytoplankton as primary producers and populations of consumer organisms including bacteria, zooplankton, benthic invertebrates, and fish. Our scientific understanding of lakes and estuaries as dynamic ecosystems is therefore dependent upon...
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This project links climate, hydrological, and ecological changes over the next 30 years in a Great Basin watershed. In recent years, climate variability on annual and decadal time scales has been recognized as greater than commonly perceived with increasing impacts on ecosystems and available water resources. Changes in vegetation distribution, composition and productivity resulting from climate change affect plant water use, which in turn can alter stream flow, groundwater and eventually available water resources. To better understand these links, project researchers implemented two computer-based numeric models in the Cleve Creek watershed in the Schell Creek Range, east of Ely, Nevada. The application of the...
Categories: Project; Types: Map Service, OGC WFS Layer, OGC WMS Layer, OGC WMS Service; Tags: 2013, CASC, Cleve Creek, Climate, Completed, All tags...
Recent increases in the atmospheric concentrations of carbon dioxide and methane have emphasized the need for a more complete understanding of the processes that control carbon transfer among air, land, and water. Knowledge of the amount, rate and chemical form of carbon transfer across environmental interfaces, such as the land-air and water-air interfaces, is of particular importance. These fluxes are commonly controlled by a combination of physical, biological, and chemical processes at or near the interface. Isolation of the primary mechanisms that determine carbon transfer across the interface allows for development of process-based models that can be used for carbon mass transfer estimates at the ecosystem...
The overarching objective of this Project is to determine how and why biogeochemical cycles of macronutrients (i.e. C, Fe, S, etc…) and those for certain trace contaminants (e.g. Hg, Se, As, etc…) covary at the ecosystem and regional scales. General approaches to this end include: comparing and contrasting key biogeochemical pathways both within the sub-habitats of a given ecosystem and among systems that involve a wide range of land-use practices, fostering collaborations with other USGS and non-USGS scientists on projects that are regional in scope, have a fundamental biogeochemical/microbiological focus, and that balance basic environmental research with management / society ‘needs-driven’ research expanding...
Biogeochemical processes associated with the microbial community (algae, bacteria, fungi) constitute the interface between solute transport and biotic production in riverine environments. Identifying and estimating the role of biotic processes such as nitrification and denitrification by bacteria, nutrient uptake and production by epilithic algal films and decomposition of particulate and dissolved organic matter, as well as abiotic processes such as absorption, are important for understanding the linkage between terrestrial, riparian, hyporheic and in-channel contributions to the nutrient chemistry of a drainage network. Relative biotic response to solutes in transport between pristine and anthropogenically modified...
Categories: Project; Tags: Ecology, Solute Transport
This project seeks to quantify, predict, and project the relative role of plant physiology, among other ecosystem drivers, on carbon, nutrient, and trace-metal biogeochemistry. Approaches span landscape-to-molecular scales as necessary to understand how human and stochastic alterations of wetland structure influence wetland function. Research sites represent a wide range of salinity and management conditions, from rice agriculture to coastal and restored wetlands. Primary goals include evaluating management and modeling approaches to quantify wetland carbon sequestration, greenhouse gas budgets and/or mercury methylation and export.
Research objectives: i) To determine whether metals, including dissolved, colloidal and particulate metals, are bioavailable and toxic to organisms; ii) To characterize and parameterize the physiological and geochemical processes governing metal bioaccumulation, toxicity and ultimately trophic transfer in aquatic ecosystems. iii) To model metal bioaccumulation and toxicity using kinetic models iv) To develop approaches that use isotopically modified metals, metal nanoparticles and metal bound to distinct mineral phases (such as Cu on ferric oxides) to quantify their bioavailability and toxicity to organisms, in particular invertebrates; v) To use enriched metal isotopes to gain mechanistic understanding of...
My primary objective is to understand the function of the benthic community at various spatial scales with the goal of understanding and modeling the benthic community processes at the ecosystem level. Specifically, my goals are to (1) explore ecological and physical processes that are affected by the benthic community and that effect benthic community composition and function; (2) look at these processes at a variety of time scales (days to seasons and inter-annual time scales) so that hydrologic, climate, and exotic species effects on benthic communities and their ecosystems can be understood; (3) develop habitat and energetics models of dominant members of the benthic community that can be dynamically linked...
The overarching objective is to understand how anthropogenic sources of inorganic contaminants (metals) affect the structure and function of aquatic ecosystems. Elements of the research include: 1) develop and apply analytical methods and models to understand and predict metal bioavailability and bioaccumulation in aquatic organisms; 2) define effects of metal exposure on aquatic species; 3) communicate research findings to scientific and regulatory communities to support the management of water resources.
Research Objectives: To better understand the response of watershed hydrology, freshwater management and estuaries to climate variability and change. In the estuarine component of this research, there is an emphasis on the responses of physical processes that drive ecological variability and change.
map background search result map search result map Projecting the Future Encroachment of Woody Vegetation into Grasslands of the Northern Great Plains by Simulating Climate Conditions and Possible Management Actions Understanding the Impacts of Permafrost Change: Providing Input into the Alaska Integrated Ecosystem Model Understanding and Projecting Changes in Climate, Hydrology, and Ecology in the Great Basin for the Next 30 Years Understanding and Projecting Changes in Climate, Hydrology, and Ecology in the Great Basin for the Next 30 Years Projecting the Future Encroachment of Woody Vegetation into Grasslands of the Northern Great Plains by Simulating Climate Conditions and Possible Management Actions Understanding the Impacts of Permafrost Change: Providing Input into the Alaska Integrated Ecosystem Model