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At least 19 recordsLinked to original sources
USGS2023

Lactation performance in polar bears is associated with fasting time and energetic state

Females must continually make resource allocation decisions because of fitness trade-offs between self-maintenance and investment in current offspring, yet factors underpinning these decisions are unresolved. Polar bears Ursus maritimus face considerable allocation challenges when seasonal sea-ice melt precludes access to prey for several months, and females rely solely on energy stores to cover their own energetic needs and provision offspring. We tested how female polar bears regulate lactation during onshore fasting (i.e. capital breeding) and determined the consequences of moderated lactation for females and cubs. Overall, milk energy declined, and lactation was more likely to cease with longer time fasting. Lactation was partially mediated by maternal energetic state and depended on litter characteristics. Milk energy declined more sharply with fasting time (~2.6 times more strongly) in females with 2 offspring compared to those with 1. Females with cubs-of-the-year produced higher energy milk than those with yearlings, and their milk energy also increased more strongly with maternal energy density. Milk energy declines benefited females via reduced depletion of maternal energy reserves, but cub growth decreased. Altered lactation investment likely has consequences for both female survival and the fate of offspring, which could scale up to influence population dynamics. Given that Arctic warming means polar bears across much of their range will experience longer periods without access to primary prey, our results underscore how lactation will likely become increasingly compromised.

Marine Ecology Progress Series↗
USGS2016

Estimation of time-variable fast flow path chemical concentrations for application in tracer-based hydrograph separation analyses

Mixing models are a commonly used method for hydrograph separation, but can be hindered by the subjective choice of the end-member tracer concentrations. This work tests a new variant of mixing model that uses high-frequency measures of two tracers and streamflow to separate total streamflow into water from slowflow and fastflow sources. The ratio between the concentrations of the two tracers is used to create a time-variable estimate of the concentration of each tracer in the fastflow end-member. Multiple synthetic data sets, and data from two hydrologically diverse streams, are used to test the performance and limitations of the new model (two-tracer ratio-based mixing model: TRaMM). When applied to the synthetic streams under many different scenarios, the TRaMM produces results that were reasonable approximations of the actual values of fastflow discharge (±0.1% of maximum fastflow) and fastflow tracer concentrations (±9.5% and ±16% of maximum fastflow nitrate concentration and specific conductance, respectively). With real stream data, the TRaMM produces high-frequency estimates of slowflow and fastflow discharge that align with expectations for each stream based on their respective hydrologic settings. The use of two tracers with the TRaMM provides an innovative and objective approach for estimating high-frequency fastflow concentrations and contributions of fastflow water to the stream. This provides useful information for tracking chemical movement to streams and allows for better selection and implementation of water quality management strategies.

Water Resources Research↗
USGS2001

Intermittent feeding in a migratory omnivore: Digestion and body composition of American Black Duck during autumn

Birds fast intermittently during weather disturbances and migration. We tested responses of black duck to lost feeding days during autumn mass gain. Nine adult males were fed a pelleted diet (1.5% fat, 15.8% protein, and 18.3% neutral detergent fiber) and caged indoors during September and October (12 h light; 17°–24°C) to measure balances over 14 d when fed ad lib. each day and fasted intermittently for 2 d wk −1 (short fast) or 4 d wk −1 (long fast). Body mass (1,081 g), body water content, and metabolizable intakes of energy and protein were maintained as daily intakes of dry matter increased to 1.65 (short fast) and 2.35 (long fast) times the unfasted level. Intermittent feeding reduced metabolizability of dry matter, energy, protein, and acid detergent fiber. Concentrations of Mn provided similar estimates of metabolizability to direct measures in unfasted birds but underestimated measures of birds on long fasts. Fasting regimes continued outdoors for 9 wk when temperatures declined to −9°C. Birds on short fasts were heavier (1,373 vs. 1,241 g) and fatter (159 vs. 58 g) than those on long fasts, while body water (894 g) and protein (316 g) were similar between groups after 5 wk. Birds on long fasts subsequently gained mass when fed daily, but those on short fasts lost mass when fed each day. Omnivorous waterfowl combine ingestive and digestive flexibility with plasticity of body lipid to contend with uncertain food availability.

Physiological and Biochemical Zoology↗
USGS2002

Interpretation of K-Ar dates of illitic clays from sedimentary rocks aided by modeling

K-Ar dates of illitic clays from sedimentary rocks may contain "mixed ages," i.e., may have ages that are intermediate between the ages of end-member events. Two phenomena that may cause mixed ages are: (1) long-lasting reaction during the burial illitization of smectite: and (2) physical mixing of detrital and diagenetic components. The first phenomenon was investigated by simulation of illitization reactions using a nucleation and growth mechanism. These calculations indicate that values for mixed ages are related to burial history: for an equivalent length of reaction time, fast burial followed by slow burial produces much older mixed ages than slow burial followed by fast. The type of reaction that occurred in a rock can be determined from the distribution of ages with respect to the thickness of illite crystals. Dating of artificial mixtures confirms a non-linear relation between mixed ages and the proportions of the components. Vertical variation of K-Ar age dates from Gulf Coast shales can be modeled by assuming diagenetic illitization that overprints a subtle vertical trend (presumably of sedimentary origin) in detrital mineral content.

American Mineralogist↗
USGS1987

Effects of winter fasting and refeeding on white-tailed deer blood profiles

This study examined the effects of dietary protein, fasting, and refeeding on blood characteristics of 9 nonpregnant, female white-tailed deer ( Odocoileus virginianus ) in captivity from 23 February to 3 May 1984. Percent weight loss was greater in fasted deer than in deer fed diets of 2 crude protein levels. Fasting effects were also observed for hemoglobin (Hb), red blood cell (RBC) counts, packed cell volume (PCV), cholesterol, triglycerides, serum urea nitrogen (SUN), potassium (K), glucose, phosphorus (P), insulin, thyroxine (T4), and total protein (TP). Refeeding influenced cholesterol, sodium (Na), and calcium (Ca). Hemoglobin, PCV, Ca, P, and albumin varied with time in fasted deer. Changes over time in the fed deer occurred for several hematological and serum characteristics. Data are presented to serve as reference values for better understanding of data collected from free-ranging deer under less known conditions.

Minnesota↗
USGS2016

Demonstration of the Cascadia G‐FAST geodetic earthquake early warning system for the Nisqually, Washington, earthquake

A prototype earthquake early warning (EEW) system is currently in development in the Pacific Northwest. We have taken a two‐stage approach to EEW: (1) detection and initial characterization using strong‐motion data with the Earthquake Alarm Systems (ElarmS) seismic early warning package and (2) the triggering of geodetic modeling modules using Global Navigation Satellite Systems data that help provide robust estimates of large‐magnitude earthquakes. In this article we demonstrate the performance of the latter, the Geodetic First Approximation of Size and Time (G‐FAST) geodetic early warning system, using simulated displacements for the 2001 M w 6.8 Nisqually earthquake. We test the timing and performance of the two G‐FAST source characterization modules, peak ground displacement scaling, and Centroid Moment Tensor‐driven finite‐fault‐slip modeling under ideal, latent, noisy, and incomplete data conditions. We show good agreement between source parameters computed by G‐FAST with previously published and postprocessed seismic and geodetic results for all test cases and modeling modules, and we discuss the challenges with integration into the U.S. Geological Survey’s ShakeAlert EEW system.

Washington↗
USGS2004

A simple autocorrelation algorithm for determining grain size from digital images of sediment

Autocorrelation between pixels in digital images of sediment can be used to measure average grain size of sediment on the bed, grain-size distribution of bed sediment, and vertical profiles in grain size in a cross-sectional image through a bed. The technique is less sensitive than traditional laboratory analyses to tails of a grain-size distribution, but it offers substantial other advantages: it is 100 times as fast; it is ideal for sampling surficial sediment (the part that interacts with a flow); it can determine vertical profiles in grain size on a scale finer than can be sampled physically; and it can be used in the field to provide almost real-time grain-size analysis. The technique can be applied to digital images obtained using any source with sufficient resolution, including digital cameras, digital video, or underwater digital microscopes (for real-time grain-size mapping of the bed). ?? 2004, SEPM (Society for Sedimentary Geology).

Journal of Sedimentary Research↗
USGS2019

The US Geological Survey’s Earth Mapping Resources Initiative (Earth MRI)—Providing framework geologic, geophysical, and elevation data to the nation’s critical mineral-bearing regions

New detailed mapping of the geologic resources of the Nation has the potential to significantly close the gap in the essential data needed to fuel a modern era of economic development and technological innovation, while at the same time dramatically enhancing our understanding of the fundamental way geology impacts everyday life, from the domestic critical mineral resources that are necessary for modern technology and the economy, to domestic energy and water resources, geologic hazards, agriculture, and other pressing needs. The U.S. Geological Survey established the Earth Resources Mapping Initiative (Earth MRI) to address the shortfall in geologic, geophysical, and elevation data with sufficient detail to support evaluation of regions in the United States that have potential to host critical mineral resources. The new effort is a collaboration with the Association of American State Geologists, who are providing new detailed geologic maps and making available online archived data and information related to critical mineral resources. The geophysical and lidar surveys are being contracted through industry specialists to assure that high-quality data are available to the public. This article provides an overview of the Earth MRI effort with discussions on the initial geophysical surveys funded for areas that have known potential for rare earth element resources. Subsequent projects are being designed to address areas that may host other critical mineral resources.

Fast Times↗
USGS2015

Turbidity, light, temperature, and hydropeaking control primary productivity in the Colorado River, Grand Canyon

Dams and river regulation greatly alter the downstream environment for gross primary production (GPP) because of changes in water clarity, flow, and temperature regimes. We estimated reach-scale GPP in five locations of the regulated Colorado River in Grand Canyon using an open channel model of dissolved oxygen. Benthic GPP dominates in Grand Canyon due to fast transport times and low pelagic algal biomass. In one location, we used a 738 days time series of GPP to identify the relative contribution of different physical controls of GPP. We developed both linear and semimechanistic time series models that account for unmeasured temporal covariance due to factors such as algal biomass dynamics. GPP varied from 0 g O 2 m −2 d −1 to 3.0 g O 2 m −2 d −1 with a relatively low annual average of 0.8 g O 2 m −2 d −1 . Semimechanistic models fit the data better than linear models and demonstrated that variation in turbidity primarily controlled GPP. Lower solar insolation during winter and from cloud cover lowered GPP much further. Hydropeaking lowered GPP but only during turbid conditions. Using the best model and parameter values, the model accurately predicted seasonal estimates of GPP at 3 of 4 upriver sites and outperformed the linear model at all sites; discrepancies were likely from higher algal biomass at upstream sites. This modeling approach can predict how changes in physical controls will affect relative rates of GPP throughout the 385 km segment of the Colorado River in Grand Canyon and can be easily applied to other streams and rivers.

Arizona↗
USGS2024

Comparing risk of chronic wasting disease occurrence using Bayesian hierarchical spatial models and different surveillance types

Spatial modeling of wildlife diseases can be used to describe patterns of disease risk, understand biological mechanisms of disease occurrence, and for spatial prediction. Risk of wildlife disease occurrence in relation to environmental variables is often modeled and predicted using Markov chain Monte Carlo (MCMC) methods, which are unsuitable for large datasets and those covering large spatial extents. Integrated nested Laplace approximation (INLA) and INLA using the stochastic partial differential equation (INLA-SPDE) approach have become popular alternatives to MCMC for Bayesian inference because of their fast computational time and ability to process large datasets. Studies investigating risk of disease occurrence in wildlife, to our knowledge, have not yet compared Bayesian hierarchical spatial models over large spatial extents using real world data. Using chronic wasting disease (CWD) surveillance data from white-tailed deer ( Odocoileus virginianus ) collected in Pennsylvania, United States, as a case study, we first demonstrate how parameter estimates compare among MCMC, INLA, and INLA-SPDE modeling frameworks. We then model CWD (detected/non-detected) using INLA-SPDE over a much larger spatial extent than has been conducted previously for this disease to determine how surveillance type (e.g., hunter harvest, roadkill, or all surveillance) influences model parameters and predicted risk of CWD occurrence at locations not sampled. Fixed effects considered in the models included deer age and sex, elevation, slope, distance to streams, percent clay, and proportion of two habitat classes (forest and open) known to influence deer movements. We found INLA to produce comparable estimates to MCMC and permit modeling large datasets covering expansive spatial extents much faster and more efficiently than MCMC. We identified potential biases in surveillance types, indicating the value of including all surveillance in models rather than only a single type. Comparing modeling tools available for mapping diseases of wildlife in relation to ecological variables at large spatial extents will guide future modeling efforts for CWD and other wildlife diseases. Understanding spatial patterns of CWD using different surveillance types can help improve understanding of CWD disease outbreaks, assist with control of CWD through geographical targeting, and inform future CWD surveillance efforts.

Ecological Modeling↗
USGS2018

Prospects for reconstructing paleoenvironmental conditions from organic compounds in polar snow and ice

Polar ice cores provide information about past climate and environmental changes over periods ranging from a few years up to 800,000 years. The majority of chemical studies have focused on determining inorganic components, such as major ions and trace elements as well as on their isotopic fingerprint. In this paper, we review the different classes of organic compounds that might yield environmental information, discussing existing research and what is needed to improve knowledge. We also discuss the problems of sampling, analysis and interpretation of organic molecules in ice. This review highlights the great potential for organic compounds to be used as proxies for anthropogenic activities, past fire events from different types of biomass, terrestrial biogenic emissions and marine biological activity, along with the possibility of inferring past temperature fluctuations and even large-scale climate variability. In parallel, comprehensive research needs to be done to assess the atmospheric stability of these compounds, their ability to be transported long distances in the atmosphere, and their stability in the archive in order to better interpret their fluxes in ice cores. In addition, specific decontamination procedures, analytical methods with low detection limits (ng/L or lower), fast analysis time and low sample requests need to be developed in order to ensure a good time resolution in the archive.

Quaternary Science Reviews↗
USGS2002

Field and laboratory investigations of inactivation of viruses (PRD1 and MS2) attached to iron oxide-coated quartz sand

Field and laboratory experiments were conducted to investigate inactivation of viruses attached to mineral surfaces. In a natural gradient transport field experiment, bacteriophage PRD1, radiolabeled with 32 P, was injected into a ferric oxyhydroxide-coated sand aquifer with bromide and linear alkylbenzene sulfonates. In a zone of the aquifer contaminated by secondary sewage infiltration, small fractions of infective and 32 P-labeled PRD1 broke through with the bromide tracer, followed by the slow release of 84% of the 32 P activity and only 0.011% of the infective PRD1. In the laboratory experiments, the inactivation of PRD1, labeled with 35 S (protein capsid), and MS2, dual radiolabeled with 35 S (protein capsid) and 32 P (nucleic acid), was monitored in the presence of groundwater and sediment from the contaminated zone of the field site. Release of infective viruses decreased at a much faster rate than release of the radiolabels, indicating that attached viruses were undergoing surface inactivation. Disparities between 32 P and 35 S release suggest that the inactivated viruses were released in a disintegrated state. Comparison of estimated solution and surface inactivation rates indicates solution inactivation is ∼3 times as fast as surface inactivation. The actual rate of surface inactivation may be substantially underestimated owing to slow release of inactivated viruses.

Environmental Science & Technology↗
USGS2010

Rapid polymerase chain reaction diagnosis of white-nose syndrome in bats

A newly developed polymerase chain reaction (PCR)-based method to rapidly and specifically detect Geomyces destructans on the wings of infected bats from small quantities (1–2 mg) of tissue is described in the current study (methods for culturing and isolating G. destructans from bat skin are also described). The lower limits of detection for PCR were 5 fg of purified fungal DNA or 100 conidia per 2 mg of wing tissue. By using histology as the standard, the PCR had a diagnostic specificity of 100% and a diagnostic sensitivity of 96%, whereas the diagnostic sensitivity of culture techniques was only 54%. The accuracy and fast turnaround time of PCR provides field biologists with valuable information on infection status more rapidly than traditional methods, and the small amount of tissue required for the test would allow diagnosis of white-nose syndrome in live animals.

Alabama, Connecticut, Indiana, Maryland, New Hamps↗
USGS1991

Response of rainbow trout to soy lecithin, choline and autoclaved isolated soy protein

Fry of rainbow trout ( Oncorhynchus mykiss ) were fed, from first feeding (mean weight, 0.12 g), basal diets containing either a nonautoclaved (raw) sodium proteinate form of isolated soy protein (ISP) or the same ISP autoclaved at 0.56 kg/cm 2 and l 10°C for 30 min. In the three‐way factorial, 16‐week study, I measured the effects of autoclaving ISP on the growth, survival, and chemical composition of rainbow trout at three levels of soy lecithin (0, 4, and 8%) and two levels of choline (0 and 0.3%). Fish fed raw ISP grew no faster with or without choline than did those fed the basal diet, but those fed heated ISP with choline showed a quantitatively small but significant advantage in weight gain. Whereas fish fed 4% lecithin with raw ISP more than tripled weight gain compared with fish fed the basal diets, fish fed 4% lecithin with heated ISP grew seven times as fast as those fed no lecithin or choline. Rainbow trout fed choline and 4% lecithin with heated ISP (but not raw ISP) grew significantly faster than those fed heated ISP and 4% lecithin alone. The higher level (8%) of lecithin promoted no more growth than the 4% lecithin with either raw or heated ISP. Among rainbow trout fed heated ISP, 4 and 8% supplemental lecithin – either with or without choline – reduced mortality to the same level, but 8% lecithin was the only concentration that significantly reduced the mortality of fish fed raw ISP. The results of calorimetry and determination of nitrogen with larger (235–375 g) rainbow trout individually held in metabolism chambers indicated that autoclaved ISP enhanced the growth and survival responses offish to lecithin by increasing digestible protein and energy and metabolizable energy. This higher amount of bioavailable energy and protein increased the deposition of body fat.

Progressive Fish-Culturist↗
USGS2016

Modeling water quality, temperature, and flow in Link River, south-central Oregon

The 2.1-km (1.3-mi) Link River connects Upper Klamath Lake to the Klamath River in south-central Oregon. A CE-QUAL-W2 flow and water-quality model of Link River was developed to provide a connection between an existing model of the upper Klamath River and any existing or future models of Upper Klamath Lake. Water-quality sampling at six locations in Link River was done during 2013–15 to support model development and to provide a better understanding of instream biogeochemical processes. The short reach and high velocities in Link River resulted in fast travel times and limited water-quality transformations, except for dissolved oxygen. Reaeration through the reach, especially at the falls in Link River, was particularly important in moderating dissolved oxygen concentrations that at times entered the reach at Link River Dam with marked supersaturation or subsaturation. This reaeration resulted in concentrations closer to saturation downstream at the mouth of Link River.

Oregon↗
USGS1982

Land subsidence in the San Joaquin Valley, California, as of 1980

Land subsidence due to ground-water overdraft in the San Joaquin Valley began in the mid-1920 's and continued at alarming rates until surface was imported through major canals and aqueducts in the 1950 's and late 1960's. In areas where surface water replaced withdrawal of ground-water, water levels in the confined system rose sharply and subsidence slowed. In the late 1960 's and early 1970 's water levels in wells recovered to levels of the 1940 's and 1950 's throughout most of the western and southern parts of the Valley, in response to the importation of surface water through the California aqueduct. During the 1976-77 drought data collected at water-level and extensometer sites showed the effect of heavy demand on the ground-water resevoir. With the ' water of compaction ' gone, artesian head declined 10 to 20 times as fast as during the first cycle of long-term drawdown that ended in the late 1960's. In the 1978-79 water levels recovered to or above the 1976 pre-drought levels. The report suggests continued monitoring of land subsidence in the San Joaquin Valley. (USGS)

Open-File Report↗
USGS2011

Real-time monitoring of CO2 storage sites: Application to Illinois Basin-Decatur Project

Optimization of carbon dioxide (CO 2 ) storage operations for efficiency and safety requires use of monitoring techniques and implementation of control protocols. The monitoring techniques consist of permanent sensors and tools deployed for measurement campaigns. Large amounts of data are thus generated. These data must be managed and integrated for interpretation at different time scales. A fast interpretation loop involves combining continuous measurements from permanent sensors as they are collected to enable a rapid response to detected events; a slower loop requires combining large datasets gathered over longer operational periods from all techniques. The purpose of this paper is twofold. First, it presents an analysis of the monitoring objectives to be performed in the slow and fast interpretation loops. Second, it describes the implementation of the fast interpretation loop with a real-time monitoring system at the Illinois Basin–Decatur Project (IBDP) in Illinois, USA.

Energy Procedia↗
USGS2000

Seismic anisotropy of the shallow crust at the Juan de Fuca Ridge

Microearthquake data recorded on four ocean bottom seismometers are used to study shear-wave splitting on the Endeavour Segment of the Juan de Fuca Ridge. The covariance matrix decomposition method is used to determine the sensor orientation from explosive shot data and to estimate the anisotropy parameters for 238 earthquake records. At three of the four sites, the results show a remarkably consistent fast direction parallel to the ridge axis. The time delays between the fast and the slow waves range from 40 to 200 ms, with an average of 90 ms. They are not clearly related to earthquake range, focal depth or source-receiver azimuth. The splitting of the shear waves is interpreted as an effect of structural anisotropy due to the presence of ridge-parallel cracks in the shallow crust. If we assume that anisotropy is concentrated in the upper 1-2 km, the splitting times require a high crack density of ~0.1.

Geophysical Research Letters↗