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Comparative measurements of stable hydrogen and oxygen isotopes in wood are hampered by the lack of proper reference materials (RMs). The U.S. Geological Survey (USGS) has prepared three powdered, whole-wood RMs, USGS54 (Pinus contorta, Canadian lodgepole pine), USGS55 (Cordia cf. dodecandra, Mexican ziricote), and USGS56 (Berchemia cf. zeyheri, South...

To assess the complexity of eruptive activity within mafic volcanic fields, we present a detailed geologic investigation of Holocene volcanism in the upper McKenzie River catchment in the central Oregon Cascades, United States. We focus on the Sand Mountain volcanic field, which covers 76 km2 and consists of 23 vents,...

The realized effect of multiple carnivores on juvenile ungulate recruitment may depend on the carnivore assemblage as well as compensation from forage and winter weather severity, which may mediate juvenile vulnerability to predation in ungulates. We used a time-to-event approach to test for the effects of risk factors on annual...

The structural architecture of Alaska is the product of a complex history of deformation along both the Cordilleran and Arctic margins of North America involving oceanic plates, subduction zones and strike-slip faults and with continental elements of Laurentia, Baltica, and Siberia. We use geological constraints to assign regions of deformation...

Playa wetlands, the dominant hydrological feature of the semi-arid U.S. High Plains providing critical ecosystem services, are being lost and degraded due to anthropogenic alterations of the short-grass prairie landscape. The primary process contributing to the loss of playas is filling of the wetland through accumulation of soil eroded and...

Light and electron microscope observations show that a brackish diatom taxon should be classified as a new species of a new genus; Pseudofrustulia lancea gen. et sp. nov. We propose separating Pseudofrustulia from other similar genera such as Frickea, Frustulia, Amphipleura, Muelleria, and Envekadea on the basis of its thickened...

A number of studies have reported the presence of wheat septoria leaf blotch (Septoria tritici; SLB) disease in Ethiopia. However, the environmental factors associated with SLB disease, and areas under risk of SLB disease, have not been studied. Here, we tested the hypothesis that environmental variables can adequately explain observed...

Strepsipterans are a group of insects with a gruesome life history and an enigmatic evolutionary past. Called ‘twisted-wing parasites’, they are minute parasitoids with a very distinct morphology (Figure 1). Alternatively thought to be related to ichneumon wasps, Diptera (flies), Coleoptera (beetles), and even Neuroptera (net-winged insects) (Pohl and Beutel,...

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...

Historical extirpations have resulted in depauperate large herbivore assemblages in many northern forests. In eastern North America, most forests are inhabited by a single wild ungulate species, white-tailed deer (Odocoileus virginianus), and relationships between deer densities and impacts on forest regeneration are correspondingly well documented. Recent recolonizations by moose (Alces...

Landsat 8, originally known as the Landsat Data Continuity Mission (LDCM), is a National Aeronautics and Space Administration (NASA)-U.S. Geological Survey (USGS) partnership that continues the legacy of continuous moderate resolution observations started in 1972. The conception of LDCM to the reality of Landsat 8 followed an arduous path extending...

Karst areas present unique hydrologic and hydrogeological characteristics that are often challenging to investigate. These characteristics are largely dependent on the extent of development of solution conduits within the underlying bedrock, and the resulting integration of surface and subsurface drainage components into a karst aquifer system. The investigation and characterization of karst aquifers typically require...

To determine whether a consumption-oriented fishery was compatible with a trophy-oriented fishery for Muskellunge Esox masquinongy, we modeled effects of a spearing fishery and recreational angling fishery on population size structure (i.e., numbers of fish ≥ 102, 114, and 127 cm) in northern Wisconsin. An individual-based simulation model was used...

There has been a considerable amount of research linking climatic variability to hydrologic responses in the western United States. Although much effort has been spent to assess and predict changes in surface water resources, little has been done to understand how climatic events and changes affect groundwater resources. This study...

We have determined source mechanisms for nine high-quality microseismic events induced during hydraulic fracturing of the Montney Shale in Canada. Seismic data were recorded using a dense regularly spaced grid of sensors at the surface. The design and geometry of the survey are such that the recorded P-wave amplitudes essentially...

Fishery managers often use catch per unit effort (CPUE) of a given taxon derived from a group of anglers, those that sought said taxon, to evaluate fishery objectives because managers assume CPUE for this group of anglers is most sensitive to changes in fish taxon density. Further, likelihood of harvest...

Throughout much of their distribution, Burbot (Lota lota ) populations are declining or have been extirpated. Burbot in the Kootenai River, Idaho represent one such imperiled population. In an effort to restore Burbot in the Kootenai River, managers have turned to conservation aquaculture. However, no appreciable increase in natural recruitment...

We have developed a physically based method for using two acoustic frequencies to measure suspended-silt-and-clay concentration, suspended-sand concentration, and suspended-sand median grain size in river cross sections at 15-minute intervals over decadal timescales. The method is strongly grounded in the extensive scientific literature on the scattering of sound by...

The global recognition of the importance of natural flow regimes to sustain the ecological integrity of river systems has led to increased societal pressure on the hydropower industry to change plant operations to improve downstream aquatic ecosystems. However, a complete reinstatement of natural flow regimes is often unrealistic when balancing...

Biological soil crusts contribute to ecosystem functions and occupy space that could be available to invasive annual grasses. Given disturbances in the semiarid shrub steppe communities, we embarked on a set of studies to investigate restoration potential of mosses in sagebrush steppe ecosystems. We examined establishment and growth of two...

The lampricides 3-trifluoromethyl-4-nitrophenol (TFM) and 2′,5-dichloro-4′-nitrosalicylanilide (niclosamide) are directly added to many tributaries of the Great Lakes that harbor the invasive parasitic sea lamprey. Despite their long history of use, the fate of lampricides is not well understood. This study evaluates the rate and pathway of direct photodegradation of both...

This study evaluated the contribution of winter rain-on-snow (ROS) events to annual and seasonal nitrate (N-NO3) export and identified the regional meteorological drivers of inter-annual variability in ROS N-NO3 export (ROS-N) at 9 headwater streams located across Ontario, Canada and the northeastern United States. Although on average only 3.3 %...

This paper discusses the challenges and benefits of the Grand Ethiopian Renaissance Dam (GERD), which is under construction and expected to be operational on the Blue Nile River in Ethiopia in a few years. Like many large-scale projects on transboundary rivers, the GERD has been criticized for potentially jeopardizing downstream...

The Prairie Pothole Region (PPR) in central North America consists of millions of depressional wetlands that each have considerable potential to emit methane (CH4). Changes in temperature and hydrology in the PPR from climate change may affect methane fluxes from these wetlands. To assess the potential effects of changes in...