Search Results

The Anaxyrus boreas species group currently comprises four species in western North America including the broadly distributed A. boreas, and three localized species, Anaxyrus nelsoni, Anaxyrus exsul and Anaxyrus canorus. Phylogenetic analyses of the mtDNA 12S rDNA, cytochrome oxidase I, control region, and restriction sites data, identified three major haplotype...

Cliff swallows (Petrochelidon pyrrhonota) and cave swallows (P. fulva) were sampled during the breeding season at several locations in the Rio Grande, Texas, to evaluate the potential effects of environmental contaminants on P450 aromatase activity in brain and gonads and DNA damage in blood cells. The tritiated water-release aromatase assay...

Capturing, immobilizing, and fitting radiocollars are common practices in studies of large mammals, but success is based on the assumptions that captured animals are representative of the rest of the population and that the capture procedure has negligible effects. We estimated effects of chemical immobilization on mortality rates of African...

The Campanian Manson impact structure of Iowa represents the best-preserved, large-diameter complex crater within the continental U.S. To assess the timing and potential mode of crater infilling and the possible presence of an impact event horizon, we analyzed samples from both within and distal to the impact structure for their...

Sulfur- and oxygen-isotope analyses have been obtained for sediment-hosted stratiform barite deposits in Alaska, Nevada, Mexico, and China to examine the environment of formation of this deposit type. The barite is contained in sedimentary sequences as old as Late Neoproterozoic and as young as Mississippian. If previously published data for...

Groundwater nitrification is a poorly characterized process affecting the speciation and transport of nitrogen. Cores from two sites in a plume of contamination were examined using culture-based and molecular techniques targeting nitrification processes. The first site, located beneath a sewage effluent infiltration bed, received treated effluent containing O2(> 300 µM) and NH4+ (51–800 µM). The second site was...

Fifteen polymorphic microsatellite loci were isolated from an enriched genomic library of the sand pocket mouse Chaetodipus arenarius. The mean number of alleles per locus was 11.53 (range five to 19) and the average observed heterozygosity was 0.764 (range 0.121 to 1.0). The markers will be used for detecting the...

1. Neotropical migrant birds show a clear preference for stopover habitats with ample food supplies; yet, the proximate cues underlying these decisions remain unclear. 2. For insectivorous migrants, cues associated with vegetative phenology (e.g. flowering, leaf flush, and leaf loss) may reliably predict the availability of herbivorous arthropods. Here we...

Modeling geomorphic evolution in estuaries is necessary to model the fate of legacy contaminants in the bed sediment and the effect of climate change, watershed alterations, sea level rise, construction projects, and restoration efforts. Coupled hydrodynamic and sediment transport models used for this purpose typically are calibrated to water level,...

Artificial water sources have been used for decades to enhance and restore wildlife habitat but the benefits of their use have been subject to debate. During the past century, the number of natural springs in Joshua Tree National Park, California, USA, has declined. In response to concerns about the viability...

In serial reuse systems, excretion of metabolic carbon dioxide has a significant impact on ambient pH, carbon dioxide, and un-ionized ammonia concentrations. This impact depends strongly on alkalinity, water flow rate, feeding rate, and loss of carbon dioxide to the atmosphere. A reduction in pH from metabolic carbon dioxide can...

The source of thiaminase in the Great Lakes food web remains unknown. Biochemical characterization of the thiaminase I activities observed in forage fish was undertaken to provide insights into potential thiaminase sources and to optimize catalytic assay conditions. We measured the thiaminase I activities of crude extracts from five forage...

A 443.9-m-thick, virtually undisturbed section of postimpact deposits in the Chesapeake Bay impact structure was recovered in the Eyreville A and C cores, Northampton County, Virginia, within the "moat" of the structure's central crater. Recovered sediments are mainly fine-grained marine siliciclastics, with the exception of Pleistocene sand, clay, and gravel....

Mapping and characterization of potential geologic reservoirs are key components in planning carbon dioxide (CO2) injection projects. The geometry of target and confining layers is vital to ensure that the injected CO2 remains in a supercritical state and is confined to the target layer. Also, maps of injection volume (porosity)...

The Chesapeake Bay impact structure is a complex impact crater, ??85 km in diameter, buried beneath postimpact sediments. Its main structural elements include a central uplift of crystalline bedrock, a surrounding inner crater filled with impact debris, and an annular faulted margin composed of block-faulted sediments. The gravity anomaly is...

Technical nonylphenol (tNP), used for industrial production of nonylphenol polyethoxylate surfactants, is a complex mixture of C3−10-phenols. The major components, 4-nonylphenols, are weak endocrine disruptors whose estrogenicities vary according to the structure of the branched nonyl group. Thus, accurate risk assessment requires isomer-specific determination of 4-NPs. Comprehensive...

Thousands of industrial-scale wind turbines are being built across the world each year to meet the growing demand for sustainable energy. Bats of certain species are dying at wind turbines in unprecedented numbers. Species of bats consistently affected by turbines tend to be those that rely on trees as roosts...

Choosing an appropriate sample unit is a fundamental decision in the design of ecological studies. While numerous methods have been developed to estimate organism abundance, they differ in cost, accuracy and precision.Using both field data and computer simulation modeling, we evaluated the costs and benefits associated with two methods commonly...

[No abstract available]...

Understanding the temporal and spatial dynamics of key water balance components of the Nile River will provide important information for the management of its water resources. This study used satellite-derived rainfall and other key weather variables derived from the Global Data Assimilation System to estimate and map the distribution of...

Hurricane Rita devastated gulf-front communities along the western Louisiana coast in 2005. LIDAR (light detection and ranging) topographic surveys and aerial photography collected before and after the storm showed the loss of every structure within the community of Holly Beach. Average shoreline change along western Louisiana's 140-km-long impacted shore was...

A revised version of the storm-time disturbance index Dst is calculated using hourly-mean magnetic-observatory data from four standard observatories and collected over the years 1958-2007. The calculation algorithm is a revision of that established by Sugiura et al., and which is now used by the Kyoto World Data Center for...

Beach sand contains fecal indicator bacteria, often in densities greatly exceeding the adjacent swimming waters. We examined the transferability of Escherichia coli and F+ coliphage (MS2) from beach sand to hands in order to estimate the potential subsequent health risk. Sand with high initial E. coli concentrations was collected from...

Tamarisk (Tamarix) species are among the most successful and economically costly plant invaders in the western United States, in part due to its potential to remove large amounts of water from shallow aquifers. Accordingly, local, state and federal agencies have released a new biological control - the saltcedar leaf beetle...

A study, using satellite telemetry, was conducted to determine the precise migration patterns and wintering locations of Common Loons (Gavia immer) breeding in the northeastern United States. Transmitters were implanted in 17 loons (16 adults and one juvenile) that were captured on breeding lakes in New York, New Hampshire, and...