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At least 919 records · Page 51Linked to original sources
USGS2003

Importance of benthic prey for fishes in coral reef-associated sediments

The importance of open, sandy substrate adjacent to coral reefs as habitat and a food source for fishes has been little studied in most shallow tropical waters in the Pacific, including Hawai'i. In this study, in Hanalei Bay, Hiwai'i, we identified and quantified the major invertebrate fauna (larger than 0.5 mm) in the well-characterized sands adjoining the shallow fringing reefs. Concurrently, we identified the fish species that seemed to make substantial use of these sand habitats, estimated their density there, sampled their gut contents to examine trophic links with the sand habitat, and made other observations and collections to determine the times, locations, and types of activity there. A variety of (mostly small) polychaeres were dominant in the sediments at most sampling stations, along with many small crustaceans (e.g., amphipods, isopods, ostracods, and small shrimps) and fair numbers of mollusks (especially bivalves) and small echinoids. Fish guts examined contained ???77% of the total number of benthic taxa collected, including nearly all those just listed. However, fish consumption was selective, and the larger shrimps, crabs, and small cryptic fishes were dominant in the diets of most of the numerous predator taxa. Diets of benthic-feeding fishes showed relatively low specific overlap. The fish fauna in this area included substrate-indifferent pelagics, species with various degrees of reef relatedness, reef-restricted species, and (at the other extreme) permanent cryptic sand dwellers. Data on occurrence and movements of fishes indicated that a band of sandy substrate several tens of meters wide next to the reef was an active area for fishes, and activity was considerably different at different times of day and for fish of different ages. These results imply an important trophic role for the benthos in these near-reef habitats in support of reef-associated fishes.

Pacific Science↗
USGS2011

Geodatabase of Wyoming statewide oil and gas drilling activity to 2010

The U.S. Geological Survey (USGS) compiled a geographic information system (GIS) of Wyoming statewide historical oil and gas drilling activity for the Wyoming Landscape Conservation Initiative (WLCI). The WLCI is representative of the partnerships being formed by the USGS with other Department of the Interior bureaus, State and local agencies, industry, academia, and private landowners that are committed to maintaining healthy landscapes, sustaining wildlife, and preserving recreational and grazing uses as energy resources development progresses in southwestern Wyoming. This product complements the 2009 USGS publication on oil and gas development in southwestern Wyoming http://pubs.usgs.gov/ds/437/) by approximating, based on database attributes, the time frame of drilling activity for each well (start and stop dates). This GIS product also adds current oil and gas drilling activity not only in the area encompassing the WLCI, but also statewide. Oil and gas data, documentation, and spatial data processing capabilities are available and can be downloaded from the USGS website. These data originated from the Wyoming Oil and Gas Conservation Commission (WOGCC), represent decades of oil and gas drilling (1900 to 2010), and will facilitate a landscape-level approach to integrated science-based assessments, resource management and land-use decision making.

Wyoming↗
USGS2012

Environmental setting of Lake Mead National Recreation Area: Chapter 2 in A synthesis of aquatic science for management of Lakes Mead and Mohave

Lakes Mead and Mohave provide opportunities for millions of regional, national, and international visitors to enjoy a wide array of water-based recreation in a spectacular desert setting. The national significance of the site’s recreational opportunities and scientific values led to its designation as the nation’s first National Recreation Area in 1964. The stark contrast of the deep blue lakes with spacious open water basins against a backdrop of mountain and canyon scenery creates a diversity of landscapes inviting recreation from the active to the contemplative (Maxon, 2009). The quality of the setting as a backdrop for the recreational experience has resulted in designation of approximately 200,000 acres of lands surrounding the lakes as wilderness (National Park Service, 2005).

Circular↗
USGS2016

Geologic context of recurring slope lineae in Melas and Coprates Chasmata, Mars

One of the major Mars discoveries of recent years is the existence of recurring slope lineae (RSL), which suggests that liquid water occurs on or near the surface of Mars today. These dark and narrow features emerge from steep, rocky exposures and incrementally grow, fade, and reform on a seasonal basis and are detected in images from the High Resolution Imaging Science Experiment camera. RSL are known to occur at scattered midlatitude and equatorial sites with little spatial connection to one another. One major exception is the steep, low-albedo slopes of Melas and Coprates Chasmata, in Valles Marineris where RSL are detected among diverse geologic surfaces (e.g., bedrock and talus) and landforms (e.g., inselbergs and landslides). New images show topographic changes including sediment deposition on active RSL slopes. Midwall locations in Coprates and Melas appear to have more areally extensively abundant RSL and related fans as compared with other RSL sites found on Mars. Water budget estimates for regional RSL are on the order of 10 5 to 10 6 m 3 of fluid, for depths of 10 to 100mm, and suggest that a significant amount of near-surface watermight be present. Many RSL are concentrated near local topographic highs, such as ridge crests or peaks, which is challenging to explain via groundwater or ice without a recharge mechanism. Collectively, results provide additional support for the notion that significant amounts of near-surface water can be found on Mars today and suggest that a widespread mechanism, possibly related to the atmosphere, is recharging RSL sources.

Journal of Geophysical Research E: Planets↗
USGS2019

Ten-million years of activity within the Eastern California Shear Zone from U-Pb dating of fault-zone opal

Reconstructions of long-term fault activity are essential for understanding both the mechanisms controlling fault behavior and accurate earthquake hazard assessments. Increasing evidence for temporal variations in strain accumulation suggests non-uniform strain rates over a range of historic to geologic timescales. The paucity of long-term records of fault activity has limited our ability to resolve these variations. We present a method for constraining long-term fault activity based on U-Pb dating of fault-related opal from secondary fault segments within the Eastern California Shear Zone (ECSZ). The presence of sheared and breccia-cemented opaline silica within well-exposed faults at near-surface conditions suggest that opal formation is associated with high-magnitude earthquakes capable of surface rupture (>6 M). Temporal constraints from sheared syntectonic opal (n=74) on related secondary faults from this study provide new insights on the timing of fault initiation, reactivation, and longevity. The oldest dates obtained indicate that ECSZ activity commenced at or before 10 Ma. Multiple deformation events dated within a single structure on episodically deposited and sheared opal (up to six generations), demonstrate that fault reactivation occurred over 105 year timescales (0.7-0.1 Ma). Relative probabilities of dated deformation events can be used to evaluate changes in fault activity in the past 2.5 Ma (n=60). This analysis indicates enhanced fault activity starting at 2 Ma and peaking around 1 Ma, possibly due to fault-interactions and distribution of deformation between the ECSZ and the San Andreas Fault.

California↗
USGS2006

Landscape response to deglaciation in a high relief, monsoon-influenced alpine environment, Langtang Himal, Nepal

Significant glacial fluctuations and rapid paraglacial reworking of glacigenic sediments characterize the Middle and Late Holocene of the Langtang Khola Valley, Central Nepal Himalaya. Geomorphic mapping and beryllium-10 cosmogenic radionuclide (CRN) dating of moraines and paraglacial fans were undertaken to test the existing paraglacial fan, terrace and moraine chronologies. The new dating compares favorably with prior studies that utilized radiocarbon, adding additional support to the assumption that fan and terrace formation are strongly linked to deglaciation. Fan and terrace denudation rates are so rapid in this region, averaging ∼33 mm/yr, that no depositional landforms older than 5 ka are preserved within 250 m of the valley floor. In this region, high rates of denudation during the Late Quaternary are driven by a combination of rapid tectonic uplift, numerous glacial fluctuations and intense weathering driven by an active monsoon climate. Extensive reworking of glacigenic sediments in Langtang during the latter half of the Holocene is consistent with studies completed in other areas of the Himalaya that are strongly influenced by the monsoon.

Langtang Himal↗
USGS2004

Historical trends in occurrence and atmospheric inputs of halogenated volatile organic compounds in untreated ground water used as a source of drinking water

Analyses of samples of untreated ground water from 413 community-, non-community- (such as restaurants), and domestic-supply wells throughout the US were used to determine the frequency of detection of halogenated volatile organic compounds (VOCs) in drinking-water sources. The VOC data were compiled from archived chromatograms of samples analyzed originally for chlorofluorocarbons (CFCs) by purge-and-trap gas chromatography with an electron-capture detector (GC-ECD). Concentrations of the VOCs could not be ascertained because standards were not routinely analyzed for VOCs other than trichloromonofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12) and 1,1,2-trichloro-1,2,2-trifluoroethane (CFC-113). Nevertheless, the peak areas associated with the elution times of other VOCs on the chromatograms can be classified qualitatively to assess concentrations at a detection limit on the order of parts per quadrillion. Three or more VOCs were detected in 100% (percent) of the chromatograms, and 77.2% of the samples contained 10 or more VOCs. The maximum number of VOCs detected in any sample was 24. Modeled ground-water residence times, determined from concentrations of CFC-12, were used to assess historical trends in the cumulative occurrence of all VOCs detected in this analysis, as well as the occurrence of individual VOCs, such as CFC-11, carbon tetrachloride (CCl 4 ), chloroform and tetrachloroethene (PCE). The detection frequency for all of the VOCs detected has remained relatively constant from approximately 1940 to 2000; however, the magnitude of the peak areas on the chromatograms for the VOCs in the water samples has increased from 1940 to 2000. For CFC-11, CCl 4 , chloroform and PCE, small peaks decrease from 1940 to 2000, and large peaks increase from 1940 to 2000. The increase in peak areas on the chromatograms from analyses of more recently recharged water is consistent with reported increases in atmospheric concentrations of the VOCs. Approximately 44% and 6.7% of the CCl 4 and PCE detections, respectively, in pre-1940 water, and 68% and 62% of the CCl 4 and PCE detections, respectively, in water recharged in 2000 exceed solubility equilibrium with average atmospheric concentrations. These exceedences can be attributed to local atmospheric enrichment or direct contaminant input to ground-water flow systems. The detection of VOCs at concentrations indicative of atmospheric sources in 100% of the samples indicates that untreated drinking water from ground-water sources in the US recharged within the past 60 years has been affected by anthropogenic activity. Additional inputs from a variety of sources such as spills, underground injections and leaking landfills or storage tanks increasingly are providing additional sources of contamination to ground water used as drinking-water sources.

Science of the Total Environment↗
USGS2019

The dilemma of pest suppression in the conservation of endangered species

In the conservation of endangered species, active suppression of a population of one native species to benefit another native species poses particular challenges. Obvious examples include predator control and nest parasite reduction. Less obvious is the control of blood-feeding arthropods. We present a case study on the effect of blood-feeding black flies (Simulium spp.) on reintroduced Whooping Cranes (Grus americana). Our intent is to provide a transferrable, science-driven approach for determining the effects of blood-feeding arthropods on endangered vertebrates, and demonstrate an approach for guiding selection of management actions for managers faced with competing objectives. A multi-year experiment demonstrated that black flies reduce nest success in reintroduced cranes by driving the birds off their nests during incubation. Deciding how to respond, however, is complicated because the target black flies are native species that serve important ecological functions. We suggest that a decision-analytic approach can inspire the development of creative management alternatives and facilitate a transparent process that evaluates trade-offs among competing objectives. Recognizing that these decisions involve trade-offs, which must be weighed in the context of each case, is crucial to identifying alternatives that best balance multiple management objectives. Given the uncertainty about the population dynamics of blood-feeding arthropods, an adaptive management approach will offer substantial benefits.

Wisconsin↗
USGS1985

EARTHQUAKE HAZARDS IN THE OFFSHORE ENVIRONMENT.

This report discusses earthquake effects and potential hazards in the marine environment, describes and illustrates methods for the evaluation of earthquake hazards, and briefly reviews strategies for mitigating hazards. The report is broadly directed toward engineers, scientists, and others engaged in developing offshore resources. The continental shelves have become a major frontier in the search for new petroleum resources. Much of the current exploration is in areas of moderate to high earthquake activity. If the resources in these areas are to be developed economically and safely, potential earthquake hazards must be identified and mitigated both in planning and regulating activities and in designing, constructing, and operating facilities. Geologic earthquake effects that can be hazardous to marine facilities and operations include surface faulting, tectonic uplift and subsidence, seismic shaking, sea-floor failures, turbidity currents, and tsunamis.

Ocean science and engineering↗
USGS2001

Analytical data for waters of the Harvard Open Pit, Jamestown Mine, Tuolumne County, California, March 1998-September 1999

The Jamestown mine is located in the Jamestown mining district in western Tuolumne County, California (see Fig. 1). This district is one of many located on or near the Melones fault zone, a major regional suture in the Sierra Nevada foothills. The districts along the Melones fault comprise the Mother Lode gold belt (Clark, 1970). The Harvard pit is the largest of several open pits mined at the Jamestown site by Sonora Mining Corporation between 1986 and 1994 (Fig. 2; Algood, 1990). It is at the site of an historical mine named the Harvard that produced about 100,000 troy ounces of gold, mainly between 1906 and 1916 (Julihn and Horton, 1940). Sonora Mining mined and processed about 17,000,000 short tons of ore, with an overall stripping ratio of about 4.5:1, yielding about 660,000 troy ounces of gold (Nelson and Leicht, 1994). Most of this material came from the Harvard pit, which attained dimensions of about 2700 ft (830 m) in length, 1500 ft (460 m) in width, and 600 ft (185 m) in depth. The bottom of the pit is at an elevation of 870 ft (265 m). Since mining operations ceased in mid-1994, the open pit has been filling with water. As of November, 2000, lake level had reached an elevation of about 1170 ft (357 m). Water quality monitoring data gathered after mine closure showed rising levels of arsenic, sulfate, and other components in the lake, with particularly notable increases accompanying a period of rapid filling in 1995 (County of Tuolumne, 1998). The largest potential source for arsenic in the vicinity of the Harvard pit is arsenian pyrite, the most abundant sulfide mineral related to gold mineralization. A previous study of weathering of arsenian pyrite in similarly mineralized rocks at the Clio mine, in the nearby Jacksonville mining district, showed that arsenic released by weathering of arsenian pyrite is effectively attenuated by adsorption on goethite or coprecipitation with jarosite, depending upon the buffering capacity of the pyrite-bearing rock (Savage and others, 2000). Although jarosite would be expected to dissolve in water having the composition of the developing pit lake, iron oxyhydroxide species (ferrihydrite and goethite) would be stable, and strong partitioning of arsenic onto suspended particles or bottom sediments containing these iron phases would be expected. Arsenic release to the lake would not be expected until stratification develops, producing a reducing, non-circulating hypolimnion in which the iron phases would be destroyed by dissolution. The fact that arsenic concentrations increased rapidly before the pit lake was deep enough to stratify shows that arsenic may not be attenuated in the ways that the earlier Clio mine area study indicated, and suggested that our understanding of release and transport of arsenic in this environment is incomplete. Therefore, in 1997 we decided to study the chemical evolution of the Harvard pit lake as part of a project on environmental impacts of gold mining in the Sierra Nevada, and in early 1998 we developed a cooperative study with several of the investigators in the Stanford University Department of Geological and Environmental Sciences who had done the Clio study. The U.S. Geological Survey portion of the project has been funded by the Mineral Resources Program. It is anticipated that a better understanding of the release and transport of arsenic into the Harvard pit lake and its accumulation there will contribute to more accurate predictions of arsenic release from weathering of sulfide-bearing rocks exposed by mining or other activities or events, and to better forecasts of pit lake evolution in this and similar environments, leading to more effective monitoring and mitigation strategies. An accurate predictive model is needed for the Harvard pit lake to forecast trends in metal concentrations, particularly arsenic, and also concentrations of major cations and anions. As the lake approaches pre-mining groundwater levels the lake water could move down the hydrologic gradient to the southeast into domestic wells, and could also affect the surface water of Woods Creek (see Figures 1-3). This report presents data for water samples collected from March, 1998 through September, 1999. Selected preliminary data for the pit lake for the 1998 calendar year have been reported (Savage and others, 2000).

California↗
USGS2015

A hidden view of wildlife conservation: How camera traps aid science, research and management

Florida panthers are among the world’s most endangered — and elusive — animals. For approximately four decades, scientists have been researching this small population of panthers that inhabit the dense forests and swamps of south Florida. Because of their wide habitat range along with an absence of clear visual features, these animals are difficult to detect and identify. In 2013, however, researchers released a study that used camera trap images collected between 2005 and 2007 to generate the first statistically reliable density estimates for the remaining population of this subspecies. Camera traps — remotely activated cameras with infrared sensors — first gained measurable popularity in wildlife conservation in the early 1990s. Today, they’re used for a variety of activities, from species-specific research to broad-scale inventory or monitoring programs that, in some cases, attempt to detect biodiversity across vast landscapes. As this modern tool continues to evolve, it’s worth examining its uses and benefits for wildlife management and conservation.

The Wildlife Professional↗
USGS1998

Polychlorinated dibenzo-p-dioxin and dibenzofuran concentration profiles in sediment and fish tissue of the Willamette Basin, Oregon

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) are highly hydrophobic compounds that have been implicated as carcinogens and, more recently, as estrogen disrupters. An occurrence and distribution study of these compounds in the Willamette Basin, Oregon, was conducted by the U.S. Geological Survey as part of the National Water-Quality Assessment Program. Bed sediment was collected from 22 sites; fish tissue was collected from eight sites. PCDD/F were found to be ubiquitous in Willamette Basin sediment. A distinct homolog profile, dominated by octachlorodibenzo-p-dioxin, was observed in sediment throughout the basin. The PCDD homolog profile was consistent at all sites, regardless of total PCDD/F concentration, presence of point sources, subbasin size, geographic location or land use. Principal components analysis revealed a gradient among the homolog profiles that showed increasing dominance of highly chlorinated congeners where human and industrial activity increased. Tissue and bed sediment obtained from the same site did not have similar PCDD/F concentrations or homolog profiles. Fish tissue showed enrichment in less chlorinated congeners and congeners with chlorine substitutions in the 2, 3, 7 and 8 positions.

Environmental Science & Technology↗
USGS2009

Effects of uranium mining discharges on water quality in the Puerco River basin, Arizona and New Mexico

From 1967 until 1986, uranium mine dewatering increased dissolved gross alpha, gross beta, uranium and radium activities and dissolved selenium and molybdenum concentrations in the Puerco River as indicated by time trends, areal patterns involving distance from the mines and stream discharge. Additionally, increased dissolved uranium concentrations were identified in groundwater under the Puerco River from where mine discharges entered the river to approximately the Arizona-New Mexico State line about 65 km downstream. Total mass of uranium and gross alpha activity released to the Puerco River by mine dewatering were estimated as 560 Mg (560 × 10 6 g) and 260 Ci, respectively. In comparison, a uranium mill tailings pond spill on 16 July 1979, released an estimated 1.5 Mg of uranium and 46 Ci of gross alpha activity. Mass balance calculations for alluvial ground water indicate that most of the uranium released did not remain in solution. Sorption of uranium on sediments and uptake of uranium by plants probably removed the uranium from solution.

Arizona, New Mexico↗
USGS2014

Metal Mixture Modeling Evaluation project: 2. Comparison of four modeling approaches

As part of the Metal Mixture Modeling Evaluation (MMME) project, models were developed by the National Institute of Advanced Industrial Science and Technology (Japan), the U.S. Geological Survey (USA), HDR⎪HydroQual, Inc. (USA), and the Centre for Ecology and Hydrology (UK) to address the effects of metal mixtures on biological responses of aquatic organisms. A comparison of the 4 models, as they were presented at the MMME Workshop in Brussels, Belgium (May 2012), is provided herein. Overall, the models were found to be similar in structure (free ion activities computed by WHAM; specific or non-specific binding of metals/cations in or on the organism; specification of metal potency factors and/or toxicity response functions to relate metal accumulation to biological response). Major differences in modeling approaches are attributed to various modeling assumptions (e.g., single versus multiple types of binding site on the organism) and specific calibration strategies that affected the selection of model parameters. The models provided a reasonable description of additive (or nearly additive) toxicity for a number of individual toxicity test results. Less-than-additive toxicity was more difficult to describe with the available models. Because of limitations in the available datasets and the strong inter-relationships among the model parameters (log KM values, potency factors, toxicity response parameters), further evaluation of specific model assumptions and calibration strategies is needed.

Environmental Toxicology and Chemistry↗
USGS2026

Resilience thinking for human-wildlife coexistence: Bridging dynamic systems, archetypes, and transformations

As human activities and wildlife increasingly overlap in the Anthropocene, conventional conservation paradigms focused on land-sparing are shifting toward strategies that support human–wildlife coexistence. However, achieving sustainable coexistence is often hindered by a limited understanding of the dynamic social–ecological processes that drive integrated human–wildlife systems. This Special Issue explores “resilience thinking” as a scientific framework to address these knowledge gaps. By bridging sustainability and wildlife sciences, we examine how concepts such as adaptive capacity, feedback loops, system archetypes, and tipping points can illuminate the conditions that facilitate stable coexistence or lead to persistent conflict. Through diverse global case studies ranging from carnivore management in Europe to primate interactions in Indonesia, contributions highlight how societal perceptions, governance, and co-adaptation shape system trajectories. Ultimately, we argue that fostering durable coexistence requires moving beyond incremental adaptation toward transformative governance that centers on equity, relationality, and proactive management.

Ambio↗
USGS2012

Effects of activity and energy budget balancing algorithm on laboratory performance of a fish bioenergetics model

We evaluated the performance of the Wisconsin bioenergetics model for lake trout Salvelinus namaycush that were fed ad libitum in laboratory tanks under regimes of low activity and high activity. In addition, we compared model performance under two different model algorithms: (1) balancing the lake trout energy budget on day t based on lake trout energy density on day t and (2) balancing the lake trout energy budget on day t based on lake trout energy density on day t + 1. Results indicated that the model significantly underestimated consumption for both inactive and active lake trout when algorithm 1 was used and that the degree of underestimation was similar for the two activity levels. In contrast, model performance substantially improved when using algorithm 2, as no detectable bias was found in model predictions of consumption for inactive fish and only a slight degree of overestimation was detected for active fish. The energy budget was accurately balanced by using algorithm 2 but not by using algorithm 1. Based on the results of this study, we recommend the use of algorithm 2 to estimate food consumption by fish in the field. Our study results highlight the importance of accurately accounting for changes in fish energy density when balancing the energy budget; furthermore, these results have implications for the science of evaluating fish bioenergetics model performance and for more accurate estimation of food consumption by fish in the field when fish energy density undergoes relatively rapid changes.

Transactions of the American Fisheries Society↗
USGS2010

Ecological requirements for pallid sturgeon reproduction and recruitment in the Lower Missouri River: Annual report 2009

The Comprehensive Sturgeon Research Project is a multiyear, multiagency collaborative research framework developed to provide information to support pallid sturgeon recovery and Missouri River management decisions. The general Comprehensive Sturgeon Research Project strategy is to integrate field and laboratory studies of sturgeon reproductive ecology, habitat requirements, and physiology to produce a predictive understanding of sturgeon population dynamics. The project scope of work is developed annually with cooperating research partners and in collaboration with the U.S. Army Corps of Engineers, Missouri River Recovery-Integrated Science Program. The research consists of several interdependent and complementary research tasks engaging multiple disciplines that primarily address spawning as a probable limiting factor in reproduction and survival of the pallid sturgeon. The research is multifaceted and is designed to provide information needed for management decisions impacting habitat restoration, flow modification, and pallid sturgeon population augmentation on the Missouri River, and throughout the range of the species. Research activities and progress towards understanding of the species are reported to the U.S. Army Corps of Engineers annually. This annual report details the research effort and progress made by Comprehensive Sturgeon Research Project during 2009.

Open-File Report↗