Search Results

A high prevalence of intersex or testicular oocytes (TO) in male smallmouth bass within the Potomac River drainage has raised concerns as to the health of the river. Studies were conducted to document biomarker responses both temporally and spatially to better understand the influence of normal physiological cycles, as well...

Soil nitrogen (N) is an important component in maintaining ecosystem stability, and the introduction of non-native plants can alter N cycling by changing litter quality and quantity, nutrient uptake patterns, and soil food webs. Our goal was to determine the effects of Bromus tectorum (C3) invasion on soil microbial N...

No abstract available....

Surveillance has revealed low prevalence of avian influenza viruses (AIV) in shorebirds except Ruddy Turnstones (Arenaria interpres) on the North American Atlantic coast. Similarly, of five species of shorebirds surveyed in Alaska in 2010, Ruddy Turnstones had the highest AIV antibody prevalence; prevalence of AIV RNA was low or zero....

We examined the life history of Blackbanded Darters (Percina nigrofasciata) from two streams in the Choctawhatchee River drainage, Florida, over a three-year study period. Blackbanded Darters from Turkey Creek were longer than fish from Ten Mile Creek; however, size-adjusted clutch and egg sizes were similar between populations. Larger females produced...

Apparent groundwater ages along two flow paths in the upper Patapsco aquifer of the Maryland Atlantic Coastal Plain, USA, were estimated using 14C, 36Cl and 4He data. Most of the ages range from modern to about 500 ka, with one sample at 117 km downgradient from the recharge area dated by radiogenic...

Analysis of well core and cuttings from the Black Warrior Basin in Mississippi reveals the presence of a Middle Ordovician (Whiterockian) erosional unconformity interpreted to be equivalent to the well-known Knox-Beekmantown unconformity in eastern North America. The unconformity occurs at the top of a peritidal dolostone unit known informally as...

We use a database of approximately 200,000 modified Mercalli intensity (MMI) observations of California earthquakes collected from USGS "Did You Feel It?" (DYFI) reports, along with a comparable number of peak ground-motion amplitudes from California seismic networks, to develop probabilistic relationships between MMI and peak ground velocity (PGV), peak ground...

Understanding species’ temperature tolerances in the context of concurrent environmental stressors is critical because thermal regimes of freshwater ecosystems are changing. We evaluated the critical thermal maximum (CTM) of 3 freshwater mussel species (Alasmidonta varicosa, Elliptio complanata, and Strophitus undulatus) acclimated to 2 temperatures (15 and 25°C) and exposed to...

Although sub-Saharan Africa does not contribute significantly to greenhouse gas emissions, significant adverse impacts of climate change are anticipated in this region. Countries in West Africa, which are heavily dependent on rain-fed agriculture, are projected to experience more frequent and intense droughts, altered rainfall patterns and increases in temperature through...

Cooper's Hawk (Accipiter cooperii) populations breeding in the northern portion of the species' range exhibit variation in morphological traits that conforms to predictions based on differences in prey size, tree stand density, and migratory behavior. We examined genetic structure and gene flow and compared divergence at morphological traits (PST) and...

A habitat-based aquatic macroinvertebrate study was initiated in the Lower Missouri River to evaluate relative quality and biological condition of dike pool habitats. Water-quality and sediment-quality parameters and macroinvertebrate assemblage structure were measured from depositional substrates at 18 sites. Sediment porewater was analysed for ammonia, sulphide, pH and oxidation-reduction potential....

No abstract available....

Water temperature in riverine landscapes is an important regional indicator of water quality that is influenced by both ground- and surface-water inputs, and indirectly by land use in the surrounding watershed (Brown and Krygier, 1970; Beschta et al., 1987; Chen et al., 1998; Poole and Berman, 2001).Coldwater fishes such as...

The primary objective of this study was to determine whether tree swallows (Tachycineta bicolor) demonstrate similar responses to lake pH and mercury (Hg) contamination in northern Wisconsin as do common loons (Gavia immer). Similar to common loons, Hg concentrations in the blood of tree swallow nestlings were higher, Hg concentrations...

Parameter optimization and uncertainty issues are a great challenge for the application of large environmental models like the Soil and Water Assessment Tool (SWAT), which is a physically-based hydrological model for simulating water and nutrient cycles at the watershed scale. In this study, we present a comprehensive modeling environment for...

 A monthlong time series of wave, current, salinity, and suspended-sediment measurements was made at five sites on a transect across the Mouth of Columbia River (MCR). These data were used to calibrate and evaluate the performance of a coupled hydrodynamic and wave model for the MCR based on the Delft3D...

Little Shingobee Lake and Fen are part of the extensive network of lakes and wetlands in the Shingobee River headwaters of northwestern Minnesota, designed to study the interactions between surface and ground waters. Prior to about 11.2 cal. ka, most of these lakes and wetlands were interconnected to form glacial Lake...

We evaluate the relationship between foraminiferal test size and shell geochemistry (δ13C, δ18O, and Mg/Ca) for two of the most commonly used planktonic foraminifers for paleoceanographic reconstruction in the subtropical Atlantic Ocean: the pink and white varieties of Globigerinoides ruber. Geochemical analyses were performed on foraminifera from modern core-top samples...

Maternity groups of many bat species conform to fission–fusion models and movements among diurnal roost trees and individual bats belonging to these groups use networks of roost trees. Forest disturbances may alter roost networks and characteristics of roost trees. Therefore, at the Fernow Experimental Forest in West Virginia, we examined...

A 17-year time series of near-daily sand thickness measurements at a single intertidal location was compared with 5 years of semi-annual 3-dimensional beach surveys at the same beach, and at two other beaches within the same littoral cell. The daily single point measurements correlated extremely well with the mean beach elevation...

A recent evaluation of Martis Creek Dam highlighted the potential for dam failure due to either seepage or an earthquake on nearby faults. In 1972, the U.S. Army Corps of Engineers constructed this earthen dam, located within the Truckee Basin to the north of Lake Tahoe, CA for water storage...

Nitrate leaching in the unsaturated zone poses a risk to groundwater, whereas nitrate in tile drainage is conveyed directly to streams. We developed metamodels (MMs) consisting of artificial neural networks to simplify and upscale mechanistic fate and transport models for prediction of nitrate losses by drains and leaching in the...

[No abstract available]...

Statistical relationships between annual floods at 200 long-term (85-127 years of record) streamgauges in the coterminous United States and the global mean carbon dioxide concentration (GMCO2) record are explored. The streamgauge locations are limited to those with little or no regulation or urban development. The coterminous US is divided into...