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At least 1,171 records · Page 65Linked to original sources

Selenium in the Blackfoot, Salt, and Bear River Watersheds

Nine stream sites in the Blackfoot River, Salt River, and Bear River watersheds in southeast Idaho, USA were sampled in May 2001 for water, surficial sediment, aquatic plants, aquatic invertebrates, and fish. Selenium was measured in these aquatic ecosystem components, and a hazard assessment was performed on the data. Water quality characteristics such as pH, hardness, and specific conductance were relatively uniform among the nine sites. Of the aquatic components assessed, water was the least contaminated with selenium because measured concentrations were below the national water quality criterion of 5 μ g/L at eight of the nine sites. In contrast, selenium was elevated in sediment, aquatic plants, aquatic invertebrates, and fish from several sites, suggesting deposition in sediments and food web cycling through plants and invertebrates. Selenium was elevated to concentrations of concern in fish at eight sites (> 4 μ g/g in whole body). A hazard assessment of selenium in the aquatic environment suggested a moderate hazard at upper Angus Creek (UAC) and Smoky Creek (SC), and high hazard at Little Blackfoot River (LiB), Blackfoot River gaging station (BGS), State Land Creek (SLC), upper (UGC) and lower Georgetown Creek (LGC), Deer Creek (DC), and Crow Creek (CC). The results of this study indicate that selenium concentrations from the phosphate mining area of southeast Idaho were sufficiently elevated in several ecosystem components to cause adverse effects to aquatic resources in southeastern Idaho.

Environmental Monitoring and Assessment↗

Variability of kokanee and rainbow trout food habits, distribution, and population dynamics, in an ultraoligotrophic lake with no manipulative management

Crater Lake is a unique environment to evaluate the ecology of introduced kokanee and rainbow trout because of its otherwise pristine state, low productivity, absence of manipulative management, and lack of lotic systems for fish spawning. Between 1986 and 2004, kokanee displayed a great deal of variation in population demographics with a pattern that reoccurred in about 10 years. We believe that the reoccurring pattern resulted from density dependent growth, and associated changes in reproduction and abundance, driven by prey resource limitation that resulted from low lake productivity exacerbated by prey consumption when kokanee were abundant. Kokanee fed primarily on small-bodied prey from the mid-water column; whereas rainbow trout fed on large-bodied prey from the benthos and lake surface. Cladoceran zooplankton abundance may be regulated by kokanee. And kokanee growth and reproductive success may be influenced by the availability of Daphnia pulicaria, which was absent in zooplankton samples collected annually from 1990 to 1995, and after 1999. Distribution and diel migration of kokanee varied over the duration of the study and appeared to be most closely associated with prey availability, maximization of bioenergetic efficiency, and fish density. Rainbow trout were less abundant than were kokanee and exhibited less variation in population demographics, distribution, and food habits. There is some evidence that the population dynamics of rainbow trout were in-part related to the availability of kokanee as prey. ?? 2007 Springer Science+Business Media B.V.

Hydrobiologia↗

CALFED: An experiment in science and decisionmaking

The CALFED Bay-Delta Program faces a challenging assignment: to develop a collaborative state-federal management plan for the complex river system and involve multiple stakeholders (primarily municipal, agricultural, and environmental entities) whose interests frequently are in direct conflict. Although many resource-management issues involve multiple stakeholders and conflict is integral to their discussion, the CALFED experience is unique because of its shared state and federal roles, the magnitude and significance of stakeholder participation, and the complexity of the scientific issues involved.

Environment↗

The World Coal Quality Inventory: South America

Executive Summary-Introduction: The concepts of a global environment and economy are strongly and irrevocably linked to global energy issues. Worldwide coal production and international coal trade are projected to increase during the next several decades in an international energy mix that is still strongly dependent on fossil fuels. Therefore, worldwide coal use will play an increasingly visible role in global environmental, economic, and energy forums. Policy makers require information on coal, including coal quality data, to make informed decisions regarding domestic coal resource allocation, import needs and export opportunities, foreign policy objectives, technology transfer policies, foreign investment prospects, environmental and health assessments, and byproduct use and disposal issues. The development of a worldwide, reliable, coal quality database would help ensure the most economically and environmentally efficient global use of coal. The U.S. Geological Survey (USGS), in cooperation with many agencies and scientists from the world's coal producing countries, originally undertook a project to obtain representative samples of coal from most of the world's producing coal provinces during a limited period of time (roughly 1998-2005), which is called the World Coal Quality Inventory (WoCQI). The multitude of producing coal mines, coal occurrences, or limited accessibility to sites in some countries can preclude collecting more than a single sample from a mine. In some areas, a single sample may represent an entire coal mining region or basin. Despite these limitations in sampling and uneven distribution of sample collection, the analytical results can still provide a general overview of world coal quality. The USGS intends to present the WoCQI data in reports and, when possible, in Geographic Information System (GIS) products that cover important coal bearing and producing regions.

Open-File Report↗

Energetic constraints and the paradox of a diffusing population in a heterogeneous environment

Previous mathematical analyses have shown that, for certain parameter ranges, a population, described by logistic equations on a set of connected patches, and diffusing among them, can reach a higher equilibrium total population when the local carrying capacities are heterogeneously distributed across patches, than when carrying capacities having the same total sum are homogeneously distributed across the patches. It is shown here that this apparently paradoxical result is explained when the resultant differences in energy inputs to the whole multi-patch system are taken into account. We examine both Pearl–Verhulst and Original Verhulst logistic models and show that, when total input of energy or limiting resource, is constrained to be the same in the homogeneous and heterogeneous cases, the total population in the heterogeneous patches can never reach an asymptotic equilibrium that is greater than the sum of the carrying capacities over the homogeneous patches. We further show that, when the dynamics of the limiting resources are explicitly modeled, as in a chemostat model, the paradoxical result of the logistic models does not occur. These results have implications concerning the use of some ubiquitous equations of population ecology in modeling populations in space.

Theoretical Population Biology↗

On-demand global Landsat evapotranspiration product: Development, evaluation, and dissemination

Global actual evapotranspiration (ET) is one of the essential climate variables needed to understand and manage the relationships among food, energy, and water resources. The U.S. Geological Survey Earth Resources Observation and Science (EROS) Center launched a provisional ET product in 2020, offering on-demand, field-scale global coverage derived from Landsat data through the EROS Science Processing Architecture (ESPA) platform. The ESPA interface provides ET data for cloud-free Landsat overpasses starting in 1982 with Landsat 4 through the current Landsat 9. The ET data are delivered as a Provisional Level-3 Science product created using the Operational Simplified Surface Energy Balance (SSEBop) model. Landsat surface temperature and reference ET are the main model drivers along with vegetation index and net radiation for model parameterization. A large volume of Landsat-based ET orders (e.g., over 1,200,000 images from June 2020 through December 2025) around the world indicate increasing awareness and application of the ET data. The ESPA platform enables land and water resource managers and researchers to access a first-order ET product without requiring advanced knowledge of remote sensing technology or evapotranspiration modeling. We present the methodology and workflow of the on-demand Landsat ET product and its performance evaluations over diverse hydro-climatic settings. The product can help estimate field-scale consumptive water use and thus quickly and consistently assess historical water use, allocation, and budget to inform water management under changing environments. Future ET data aggregated to monthly and seasonal time scales are expected to enhance integration with decision-making tools and procedures.

Remote Sensing of Environment↗

Assessing land-use impacts on biodiversity using an expert systems tool

Habitat alteration, in the form of land-use development, is a leading cause of biodiversity loss in the U.S. and elsewhere. Although statutes in the U.S. may require consideration of biodiversity in local land-use planning and regulation, local governments lack the data, resources, and expertise to routinely consider biotic impacts that result from permitted land uses. We hypothesized that decision support systems could aid solution of this problem. We developed a pilot biodiversity expert systems tool (BEST) to test that hypothesis and learn what additional scientific and technological advancements are required for broad implementation of such a system. BEST uses data from the U.S. Geological Survey's Gap Analysis Program (GAP) and other data in a desktop GIS environment. The system provides predictions of conflict between proposed land uses and biotic elements and is intended for use at the start of the development review process. Key challenges were the development of categorization systems that relate named land-use types to ecological impacts, and relate sensitivities of biota to ecological impact levels. Although the advent of GAP and sophisticated desktop GIS make such a system feasible for broad implementation, considerable ongoing research is required to make the results of such a system scientifically sound, informative, and reliable for the regulatory process. We define a role for local government involvement in biodiversity impact assessment, the need for a biodiversity decision support system, the development of a prototype system, and scientific needs for broad implementation of a robust and reliable system.

Landscape Ecology↗

Tracking animals in freshwater with electronic tags: past, present and future

Considerable technical developments over the past half century have enabled widespread application of electronic tags to the study of animals in the wild, including in freshwater environments. We review the constraints associated with freshwater telemetry and biologging and the technical developments relevant to their use. Technical constraints for tracking animals are often influenced by the characteristics of the animals being studied and the environment they inhabit. Collectively, they influence which and how technologies can be used and their relative effectiveness. Although radio telemetry has historically been the most commonly used technology in freshwater, passive integrated transponder (PIT) technology, acoustic telemetry and biologgers are becoming more popular. Most telemetry studies have focused on fish, although an increasing number have focused on other taxa, such as turtles, crustaceans and molluscs. Key technical developments for freshwater systems include: miniaturization of tags for tracking small-size life stages and species, fixed stations and coded tags for tracking large samples of animals over long distances and large temporal scales, inexpensive PIT systems that enable mass tagging to yield population- and community-level relevant sample sizes, incorporation of sensors into electronic tags, validation of tag attachment procedures with a focus on maintaining animal welfare, incorporation of different techniques (for example, genetics, stable isotopes) and peripheral technologies (for example, geographic information systems, hydroacoustics), development of novel analytical techniques, and extensive international collaboration. Innovations are still needed in tag miniaturization, data analysis and visualization, and in tracking animals over larger spatial scales (for example, pelagic areas of lakes) and in challenging environments (for example, large dynamic floodplain systems, under ice). There seems to be a particular need for adapting various global positioning system and satellite tagging approaches to freshwater. Electronic tagging provides a mechanism to collect detailed information from imperilled animals and species that have no direct economic value. Current and future advances will continue to improve our knowledge of the natural history of aquatic animals and ecological processes in freshwater ecosystems while facilitating evidence-based resource management and conservation.

Animal Biotelemetry↗

The emerging role of lidar remote sensing in coastal research and resource management

Knowledge of coastal elevation is an essential requirement for resource management and scientific research. Recognizing the vast potential of lidar remote sensing in coastal studies, this Special Issue includes a collection of articles intended to represent the state-of-the-art for lidar investigations of nearshore submerged and emergent ecosystems, coastal morphodynamics, and hazards due to sea-level rise and severe storms. Some current applications for lidar remote sensing described in this Special Issue include bluegreen wavelength lidar used for submarine coastal benthic environments such as coral reef ecosystems, airborne lidar used for shoreline mapping and coastal change detection, and temporal waveform-resolving lidar used for vegetation mapping.

Journal of Coastal Research↗

Relations of Water Quality to Agricultural Chemical Use and Environmental Setting at Various Scales - Results from Selected Studies of the National Water-Quality Assessment Program

In 1991, the U.S. Geological Survey (USGS) began studies of 51 major river basins and aquifers across the United States as part of the National Water-Quality Assessment (NAWQA) Program to provide scientifically sound information for managing the Nation's water resources. The major goals of the NAWQA Program are to assess the status and long-term trends of the Nation's surface- and ground-water quality and to understand the natural and human factors that affect it (Gilliom and others, 1995). In 2001, the NAWQA Program began a second decade of intensive water-quality assessments. The 42 study units for this second decade were selected to represent a wide range of important hydrologic environments and potential contaminant sources. These NAWQA studies continue to address the goals of the first decade of the assessments to determine how water-quality conditions are changing over time. In addition to local- and regional-scale studies, NAWQA began to analyze and synthesize water-quality status and trends at the principal aquifer and major river-basin scales. This fact sheet summarizes results from four NAWQA studies that relate water quality to agricultural chemical use and environmental setting at these various scales: * Comparison of ground-water quality in northern and southern High Plains agricultural settings (principal aquifer scale); * Distribution patterns of pesticides and degradates in rain (local scale); * Occurrence of pesticides in shallow ground water underlying four agricultural areas (local and regional scales); and * Trends in nutrients and sediment over time in the Missouri River and its tributaries (major river-basin scale).

Fact Sheet↗

Using science to strengthen our Nation's resilience to tomorrow's challenges: understanding and preparing for coastal impacts

Hurricane Sandy caused unprecedented damage across some of the most densely populated coastal areas of the northeastern United States. The costly, landscape-altering destruction left in the wake of this storm is a stark reminder of our Nation’s need to become more resilient as we inevitably face future coastal hazards. As our Nation recovers from this devastating natural disaster, it is clear that accurate scientific information is essential as we seek to identify and develop strategies to address trends in coastal landscape change and reduce our future vulnerability to major storm events. To address this need, the U.S. Geological Survey (USGS) received $43.2 million in supplemental appropriations from the Department of the Interior (DOI) to conduct the scientific research needed to guide response, recovery, and rebuilding activities and to develop effective strategies for protecting coastal communities and resources in the future. This fact sheet describes how the USGS is combining interdisciplinary science with state-of-the-art technologies to achieve a comprehensive understanding of coastal change caused by Hurricane Sandy. By assessing coastal change impacts through research and by developing tools that enhance our science capabilities, support coastal stakeholders, and facilitate effective decision making, we continue to build a greater understanding of the processes at work across our Nation’s complex coastal environment—from wetlands, estuaries, barrier islands, and nearshore marine areas to infrastructure and human communities. This improved understanding will increase our resilience as we prepare for future short-term, extreme events as well as long-term coastal change.

Fact Sheet↗

Development and use of mathematical models and software frameworks for integrated analysis of agricultural systems and associated water use impacts

The development of appropriate water management strategies requires, in part, a methodology for quantifying and evaluating the impact of water policy decisions on regional stakeholders. In this work, we describe the framework we are developing to enhance the body of resources available to policy makers, farmers, and other community members in their e orts to understand, quantify, and assess the often competing objectives water consumers have with respect to usage. The foundation for the framework is the construction of a simulation-based optimization software tool using two existing software packages. In particular, we couple a robust optimization software suite (DAKOTA) with the USGS MF-OWHM water management simulation tool to provide a flexible software environment that will enable the evaluation of one or multiple (possibly competing) user-defined (or stakeholder) objectives. We introduce the individual software components and outline the communication strategy we defined for the coupled development. We present numerical results for case studies related to crop portfolio management with several defined objectives. The objectives are not optimally satisfied for any single user class, demonstrating the capability of the software tool to aid in the evaluation of a variety of competing interests.

AIMS Agriculture and Food↗

Surface water-ground water interactions along the lower Dungeness River and vertical hydraulic conductivity of streambed sediments, Clallam County, Washington, September 1999-July 2001

The Dungeness River emerges from the Olympic Mountains and flows generally north toward the Strait of Juan De Fuca, crossing the broad, fertile alluvial fan of the Sequim-Dungeness peninsula in northeastern Clallam County, Washington. Increasing competition for the peninsula's ground-water resources, changing water-use patterns, and recent requirements to maintain minimum in-stream flows to enhance endangered salmon and trout populations have severely strained the peninsula's water resources and necessitated a better understanding of the interaction between surface water and groundwater. Three methods were used to characterize the interchange between surface water and groundwater along the lower 11.8 miles of the Dungeness River corridor between September 1999 and July 2001. In-stream mini-piezometers were used to measure vertical hydraulic gradients between the river and the water-table aquifer at 27 points along the river and helped to define the distribution of gaining and losing stream reaches. Seepage runs were used to quantify the net volume of water exchanged between the river and ground water within each of five river reaches, termed 'seepage reaches.' Continuous water-level and water-temperature monitoring at two off-stream well transects provided data on near-river horizontal hydraulic gradients and temporal patterns of water exchange for a representative gaining stream reach and a representative losing stream reach. Vertical hydraulic gradients in the mini-piezometers generally were negative between river miles 11.8 and 3.6, indicating loss of water from the river to ground water. Gradients decreased in the downstream direction from an average of -0.86 at river mile 10.3 to -0.23 at river mile 3.7. Small positive gradients (+0.01 to +0.02) indicating ground-water discharge occurred in three localized reaches below river mile 3.7. Data from the seepage runs and off-stream transect wells supported and were generally consistent with the mini-piezometer findings. An exception occurred between river miles 8.1 and 5.5 where seepage results showed a small gain and the mini-piezometers showed negative gradients. Vertical hydraulic conductivity of riverbed sediments was estimated using hydraulic gradients measured with the mini-piezometers and estimated seepage fluxes. The resulting conductivity values ranged from an average of 1 to 29 feet per day and are similar to values reported for similar river environments elsewhere. The results of this study will be used to calibrate a transient, three-dimensional ground-water flow model of the Sequim-Dungeness peninsula. The model will be used to assess the potential effects on ground-water levels and river flows that result from future water use and land-use changes on the peninsula.

Water-Resources Investigations Report↗

Management applications of discontinuity theory

Human impacts on the environment are multifaceted and can occur across distinct spatiotemporal scales. Ecological responses to environmental change are therefore difficult to predict, and entail large degrees of uncertainty. Such uncertainty requires robust tools for management to sustain ecosystem goods and services and maintain resilient ecosystems. We propose an approach based on discontinuity theory that accounts for patterns and processes at distinct spatial and temporal scales, an inherent property of ecological systems. Discontinuity theory has not been applied in natural resource management and could therefore improve ecosystem management because it explicitly accounts for ecological complexity. Synthesis and applications . We highlight the application of discontinuity approaches for meeting management goals. Specifically, discontinuity approaches have significant potential to measure and thus understand the resilience of ecosystems, to objectively identify critical scales of space and time in ecological systems at which human impact might be most severe, to provide warning indicators of regime change, to help predict and understand biological invasions and extinctions and to focus monitoring efforts. Discontinuity theory can complement current approaches, providing a broader paradigm for ecological management and conservation.

Journal of Applied Ecology↗

Establishing historical baselines of arthropod assemblages using rodent paleomiddens

Aim Arthropods are under-represented in paleoecological studies but are critical agents in ecological processes. Despite rigorous documentation of diverse arthropod assemblages from ancient rodent (or paleo) middens worldwide, their use for studying ancient arthropod diversity has stalled in recent decades. Here, we review published studies to identify how paleomidden arthropods can be leveraged to address significant questions in ecology and synthesise spatiotemporal trends in ancient arthropod diversity. Location Global with a focus on the Americas. Time Period From ~40,000 to 100 years before present. Major Taxa Studied Fossil arthropods preserved in rodent paleomiddens. Methods We identified four primary objectives in ecology that can be advanced using paleomidden arthropod fossils: the reconstruction of ancient biodiversity, the elucidation of mechanisms and processes driving arthropod range shifts, the incorporation of arthropods into ancient trophic webs, and the assessment of adaptive responses to changing environments. Results We identified 20 papers reporting arthropod remains, of which 14 provided data suitable for quantitative analyses. Although no significant differences in arthropod community diversity were found across broad geographic regions, substantial differences in community structure were observed. In North America, we also detected a decline in arthropod diversity from 10 to 5 ka BP, driven primarily by the absence of high-diversity assemblages during this period. Main Conclusions Paleomidden arthropods remain an underutilised ecological resource that can be leveraged to improve the inferential scope of arthropod research across spatiotemporal gradients. Collaboration between paleo- and neoecologists could help expand the sampling of ancient and modern arthropod communities, particularly those associated with paleomiddens, to create high-resolution datasets spanning important periods in biogeographical history. Paleomidden arthropods will remain a fundamental component for understanding arthropod biodiversity changes in the past, present, and future.

Global Ecology and Biogeography↗

Peralkaline- and calc-alkaline-hosted volcanogenic massive sulfide deposits of the Bonnifield District, East-Central Alaska

Volcanogenic massive sulfide (VMS) Zn-Pb-Cu-Ag-Au deposits of the Bonnifield mining district formed during Late Devonian-Early Mississippian magmatism along the western edge of Laurentia. The largest deposits, Dry Creek and WTF, have a combined resource of 5.7 million tonnes at 10% Zn, 4% Pb, 0.3% Cu, 300 grams per tonne (g/t) Ag, and 1.6 g/t Au. These polymetallic deposits are hosted in high field strength element (HFSE)- and rare-earth element (REE)-rich peralkaline (pantelleritic) metarhyolite, and interlayered pyritic argillite and mudstone of the Mystic Creek Member of the Totatlanika Schist Formation. Mystic Creek metarhyolite and alkali basalt (Chute Creek Member) constitute a bimodal pair that formed in an extensional environment. A synvolcanic peralkaline quartz porphyry containing veins of fluorite, sphalerite, pyrite, and quartz intrudes the central footwall at Dry Creek. The Anderson Mountain deposit, located ~32 km to the southwest, occurs within calc-alkaline felsic to intermediate-composition metavolcanic rocks and associated graphitic argillite of the Wood River assemblage. Felsic metavolcanic rocks there have only slightly elevated HFSEs and REEs. The association of abundant graphitic and siliceous argillite with the felsic volcanic rocks together with low Cu contents in the Bonnifield deposits suggests classification as a siliciclastic-felsic type of VMS deposit. Bonnifield massive sulfides and host rocks were metamorphosed and deformed under greenschist-facies conditions in the Mesozoic. Primary depositional textures, generally uncommon, consist of framboids, framboidal aggregates, and spongy masses of pyrite. Sphalerite, the predominant base metal sulfide, encloses early pyrite framboids. Galena and chalcopyrite accompanied early pyrite formation but primarily formed late in the paragenetic sequence. Silver-rich tetrahedrite is a minor late phase at the Dry Creek deposit. Gold and Ag are present in low to moderate amounts in pyrite from all of the deposits; electrum inclusions occur in Dry Creek sphalerite. Contents and ratios of trace elements in graphitic argillite that serve as proxies for the redox state of the bottom waters in the basin indicate that Dry Creek mineralization took place in suboxic to periodically anoxic bottom waters. Trace element data show higher contents of Tl-Mn-As in pyrite from the Anderson Mountain deposit compared to the Dry Creek or WTF deposits and thus suggest that Anderson Mountain may have formed at lower temperatures or under slightly more oxidizing conditions. No exact modern analogue for the tectonic setting of the Bonnifield VMS deposits is known, although the back-arc regions of the Okinawa Trough and Woodlark Basin satisfy the requirement for a submarine, extensional setting adjacent to a continental margin. Limited occurrences of peralkaline volcanic rocks occur in these two potential analogues, but the peralkalinity of those rocks is much less than that of the Mystic Creek Member metarhyolites in the Bonnifield district. The highly elevated trace element (e.g., Zr, Nb) contents of Mystic Creek metarhyolites suggest that a better analogue may be a submarine rifted continental margin. The calc-alkaline composition of the host rocks to the Anderson Mountain deposit suggests that mineralization there formed in a continental margin arc, outboard of the extended continental margin setting of the peralkaline-hosted Dry Creek and WTF deposits.

Alaska↗

Interdisciplinary science in support of environmental health along the United States-Mexico border

The diverse, fragile ecosystems of the borderlands have been pushed beyond sustainable levels due to rapid population growth and land-use changes. Water shortages and pollution, poor air quality, increased soil salinities, residual pesticides and heavy metal contaminants are some of the many stressors that are degrading the quality of life in the borderlands. The relationship between human health and environmental quality challenges public officials, medical professionals, and resource managers on both sides of the border in their efforts to provide for and maintain healthy communities. To help understand the relationship between environmental and human health, the U.S. Geological Survey's (USGS) Border Environmental Health Initiative (BEHI) created an Internet Map Service (IMS) with binational georeferenced data. The goal is to have seamless integration of borderwide datasets at regional and local scales that can lend understanding of the linkages between the condition of the physical environment and public health issues.

Fact Sheet↗

Coastal estuaries and lagoons: The delicate balance at the edge of the sea

Coastal communities are increasingly concerned about the dynamic balance between freshwater and saltwater because of its implications for societal, economic, and ecological resources. While the mixing of freshwater and saltwater sources defines coastal estuaries and lagoons, sudden changes in this balance can have a large effect on critical ecosystems and infrastructure. Any change to the delivery of water from either source has the potential to affect the health of both humans and natural biota and also to damage coastal infrastructure. This fact sheet discusses the potential of major shifts in the dynamic freshwater-saltwater balance to alter the environment and coastal stability.

Fact Sheet↗