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USGS1953

The use of soils and paleosols for interpreting geomorphic and climatic history of arid regions

The study of modern surface soils, and ancient weathering zones, which occur either buried or as surface relicts, has contributed materially to understanding the complex events of the glacial and post-glacial period both in glaciated areas and in regions not influenced by glaciation. Most work of this kind in the United States has been done by geologists. Numerous Pleistocene geologists have noted weathered zones between sheets of glacial drift or loess in the middle western United States. These include Condra, et al 5 ; Frye 7 ; Frye and Leonard 8 ; Kay and Pearce 13 ; Leighton and MacClintock 15 ; Leverett 16 , 17 , 18 ; Lugn 19 ; Peltier 23 ; Schultz and Stout 26 ; Schultz, et al 27 ; and Simonson 28 . Kay and Pearce 13 interpreted the weathered zones between sheets of glacial drift as profiles of ancient soils which they referred to as gumbotil. Hseung, Marshall and Krusekopf 10 have recently questioned the pedogenic character of gumbotil, but have failed to offer a satisfactory alternative explanation. Thorp, and coworkers 30 , in a general review of buried soils, apparently consider gumbotil a product of ancient soil-forming processes.

Research Council of Israel Special Publication↗

USGS2021

Alaska landbird montoring survey: Alaska regional protocol framework for monitoring landbirds using point counts

Alaska provides habitat for 143 species of landbirds that occur regularly in the state, about half of which breed predominantly north of the border between the contiguous United States and Canada. The road-based North American Breeding Bird Survey (BBS) provides some data on population trends in Alaska, but most northern populations are inadequately monitored by this program because of a paucity of roads. To remedy this deficiency, Boreal Partners in Flight developed the Alaska Landbird Monitoring Survey (ALMS) to monitor breeding populations of landbirds in off-road areas of Alaska in tandem with data collected from the roadside BBS. The primary objective of ALMS is to monitor long-term population trends of landbirds and other species that can be monitored by diurnal point counts during the breeding season, including many shorebirds and aquatic birds. A secondary objective is to estimate landbird densities by habitat, which can be used to model avian distribution and abundance across Alaska. ALMS is a collaborative program whereby agencies and other entities conduct standardized surveys of breeding birds and their habitats on the lands they manage and then contribute the data to the U.S. Geological Survey Alaska Science Center for storage and analysis. The short-term implementation goal of ALMS is to monitor birds systematically within each of 100 randomly selected survey blocks, thereby matching the number of BBS surveys conducted in each of Alaska's five Bird Conservation Regions (BCRs). Each block has a mini-grid of 15−25 points that are surveyed biennially, with half of the blocks surveyed in alternating years. Survey blocks are stratified by accessibility and cost-effectiveness. Refuges may opt to limit sites to those accessible by foot, vehicle, boat, or fixed-wing aircraft, as these can be surveyed more inexpensively and reliably over time. Observers survey each point within a survey block for birds using a 10-min point count once per summer on a biennial basis. They collect corresponding habitat data during the first visit and at subsequent 10-year intervals or whenever a disturbance (e.g., fire, wind) has caused a significant change. USGS analyzes ALMS data jointly with BBS data to test for differences between off-road and roadside areas and to increase power to detect statewide trends. Additional blocks can be surveyed in areas that are more difficult and expensive to access as resources become available in the future. Long-term monitoring enables detection of change in bird populations in relation to fire, disease and insect damage, resource development, climate-related change, and other landscape-level disturbances across Alaska. Results from ALMS can also help prioritize conservation and research towards species before they become endangered and require expensive recovery programs.

Alaska↗

USGS2025

Laying sequence and oceanographic factors affect egg size in Scripps's Murrelets Synthliboramphus scrippsi at Santa Barbara Island

Egg size is an important avian life history parameter, with larger eggs indicating greater investment of resources in the chick. Prey availability can affect such investment. We investigated the effects of oceanographic conditions and laying sequence on Scripps's Murrelet Synthliboramphus scrippsi egg size at Santa Barbara Island, California during 2009-2017. We evaluated oceanographic covariates characterizing marine productivity for their effect on egg size, including large-scale oceanographic indices such as the Pacific Decadal Oscillation (PDO) index, Oceanic Niño Index (ONI), and North Pacific Gyre Oscillation (NPGO) index. We also evaluated a larval anchovy catch-per-unit-effort (ANCHL) index and the Biologically Effective Upwelling Transport Index (BEUTI) as region-wide indices, and sea surface temperature (SST) as a local index. We evaluated oceanographic conditions over the entire year and during the breeding season only. We also considered the contribution of lagged effects to oceanographic conditions. Our results generally ran counter to our hypothesis that increased ocean productivity should increase egg size. Based on Akaike's Information Criterion, the four top-ranked models provided support for an association between larger eggs and conditions indicative of lower oceanographic productivity, including lower values of BEUTI and NPGO, and higher values of ONI, PDO, and SST. The only result that supported our hypothesis was a positive relationship between ANCHL and egg size, although the 95% confidence interval for the effect included 0. The strongest relationship detected was between laying sequence and egg size, as second eggs were considerably larger than first eggs. Our results indicate substantial complexity in the relationship between ocean productivity and seabird demography. A better understanding of how ocean productivity affects seabird breeding outcomes through multiple mechanisms will help improve predictions of how seabirds will respond to changing ocean conditions.

California↗

USGS2022

Insights on multistage rock avalanche behavior from runout modeling constrained by seismic inversions

Inversion of low-frequency regional seismic records to solve for a time series of bulk forces exerted on the earth by a landslide (a force-time function) is increasingly being used to infer volumes and dynamics of large, highly energetic landslides, such as rock avalanches and flowslides, and to provide calibration information on event dynamics and volumes for numerical landslide runout models. Much of the work to date using landslide runout modeling constrained by seismic data has focused on using single-phase models with frictional or velocity-weakening rheologies. Awareness of multistage landslide initiations is increasing, with discrete failures separated in time contributing to the final impact of an event. Our work utilizes a method for incorporating seismic data as a calibration constraint for landslide runout models, considering variable rheologies and different initiation conditions. This study presents a systematic examination of multiple rheologies and initiation conditions, and shows how these factors affect the force-time function derived from the landslide runout model. Our work confirms that, while rheology and fragmenting or initially coherent initiations affect the force-time function, multiple collapses separated by tens of seconds have the greatest impact on the shape and amplitude. We apply this method to the analysis of three real rock avalanches to better constrain plausible initiation conditions and rheology parameters using both seismic and field data. This study provides insights on how assumptions about the initiation dynamics of the source zone and the runout model definition can aid in the interpretation of seismic inversions for multistage rock avalanches.

Journal of Geophysical Research: Solid Earth↗

USGS2007

Processes Affecting Phosphorus and Copper Concentrations and Their Relation to Algal Growth in Two Supply Reservoirs in the Lower Coastal Plain of Virginia, 2002-2003, and Implications for Alternative Management Strategies

Elevated phosphorus concentrations commonly promote excessive growth of algae in waters nationwide. When such waters are used for public supply, the algae can plug filters during treatment and impart tastes and odors to the finished water. This increases treatment costs and results in finished water that may not be of the quality desired for public supply. Consequently, copper sulfate is routinely applied to many reservoirs to control algal growth but only is a 'temporary fix' and must be reapplied at intervals that can range from more than 30 days in the winter to less than 7 days in the summer. Because copper has a maximum allowable concentration in public drinking water and can be toxic to aquatic life, water suppliers commonly seek to develop alternative, long-term strategies for managing reservoirs. Because these are nationwide issues and part of the mission of the U.S. Geological Survey (USGS) is to define and protect the quality of the Nation's water resources and better understand the physical, chemical, and biological processes in wetlands, lakes, reservoirs, and estuaries, investigations into these issues are important to the fulfillment of the mission of the USGS. The City of Newport News, Virginia, provides 50 million gallons per day of treated water for public supply from Lee Hall and Harwoods Mill Reservoirs (terminal reservoirs) to communities on the lower York-James Peninsula. About 3,500 pounds of copper sulfate are applied to each reservoir at 3- to 99-day intervals to control algal growth. Consequently, the USGS, in cooperation with the City of Newport News, investigated the effects of management practices and natural processes on phosphorus (the apparent growth-limiting nutrient), copper, and algal concentrations in the terminal reservoirs to provide information that can be used to develop alternative management strategies for the terminal reservoirs. Initial parts of the research evaluated circulation and stratification in the reservoirs because these factors affect phosphorus availability to algae. Results indicate that (1) water flows through both reservoirs in a 'plug-flow' manner; (2) little water in the lower part of Lee Hall Reservoir, into which pumped water enters, flows into the upper part of the reservoir and mixes with that water; (3) Lee Hall Reservoir generally does not stratify; and (4) Harwoods Mill Reservoir stratifies from April to June through September or October into an upper epilimnion that does not mix with water in the lower hypolimnion. The ratio of dissolved nitrogen to phosphorus concentrations (N:P) for sites in both reservoirs generally was greater than 20:1, indicating that phosphorus likely is the growth-limiting nutrient in both reservoirs. Phosphorus was present predominantly as suspended, rather than dissolved, species except in the hypolimnion of Harwoods Mill Reservoir and the natural inflow represented by Baptist Run. Because Harwoods Mill Reservoir stratified, field-measured physical and chemical characteristics and concentrations of nitrogen and phosphorus species changed sharply over short depth intervals in this reservoir. Dissolved phosphorus concentration increased from 0.015 to 0.057 milligrams per liter between a depth of 15 feet (ft) and the bottom (depth of 18 ft), indicating the release of phosphorus by the decomposition of organic material and(or) the reduction of iron oxides in bed sediment and the lower water column. Because the mixing boundary between the epilimnion and the hypolimnion likely was between depths of 6 and 10 ft, such sources in the hypolimnion would not contribute phosphorus to the growth of algae in the epilimnion from which water is withdrawn for supply until the breakdown of stratification in the fall. Furthermore, laboratory studies of samples from both reservoirs indicated that dissolved phosphorus was released from suspended particles at rates of 0.0007 to 0.0019 milligrams per liter per day. At these rates of release, particl

Scientific Investigations Report↗

USGS2020

Temporospatial shifts in Sandhill Crane staging in the Central Platte River Valley in response to climatic variation and habitat change

Over 80% of the Mid-Continent Sandhill Crane ( Antigone canadensis ) Population (MCP), estimated at over 660,000 individuals, stops in the Central Platte River Valley (CPRV) during spring migration from mid-February through mid-April. Research suggests that the MCP may be shifting its distribution spatially and temporally within the CPRV. From 2002 to 2017, we conducted weekly aerial surveys of Sandhill Cranes staging in the CPRV to examine temporal and spatial trends in their abundance and distribution. Then, we used winter temperature and drought severity measures from key wintering and early migratory stopover locations to assess the impacts of weather patterns on annual migration chronology in the CPRV. We also evaluated channel width and land cover characteristics using aerial imagery from 1938, 1998, and 2016 to assess the relationship between habitat change and the spatial distribution of the MCP in the CPRV. We used generalized linear models, cumulative link models, and Akaike’s information criterion corrected for small sample sizes (AICc) to compare temporal and spatial models. Temperatures and drought conditions at wintering and migration locations that are heavily used by Greater Sandhill Cranes ( A. c. tabida ) best predicted migration chronology of the MCP to the CPRV. The spatial distribution of roosting Sandhill Cranes from 2015 to 2017 was best predicted by the proportion of width reduction in the main channel since 1938 (rather than its width in 2016) and the proportion of land cover as prairie-meadow habitat within 800 m of the Platte River. Our data suggest that Sandhill Cranes advanced their migration by an average of just over 1 day per year from 2002 to 2017, and that they continued to shift eastward, concentrating at eastern reaches of the CPRV. Climate change, land use change, and habitat loss have all likely contributed to Sandhill Cranes coming earlier and staying longer in fewer reaches of the CPRV, increasing their site use intensity. These historically unprecedented densities may present a disease risk to Sandhill Cranes and other waterbirds, including Whooping Cranes ( Grus americana ). Our models suggest that conservation actions may be maintaining Sandhill Crane densities in areas that would otherwise be declining in use. We suggest that management actions intended to mitigate trends in the distribution of Sandhill Cranes, including wet meadow restoration, may similarly benefit prairie- and braided river–endemic species of concern.

Nebraska↗

USGS1997

Land cover mapping, fire regeneration, and scaling studies in the Canadian boreal forest with 1 km AVHRR and Landsat TM data

A multitemporal 1 km advanced very high resolution radiometer (AVHRR) land cover analysis approach was used as the basis for regional land cover mapping, fire disturbance-regeneration, and multiresolution land cover scaling studies in the boreal forest ecosystem of central Canada. The land cover classification was developed by using regional field observations from ground and low-level aircraft transits to analyze spectral-temporal clusters that were derived from an unsupervised cluster analysis of monthly normalized difference vegetation index (NDVI) image composites (April-September 1992). Quantitative areal proportions of the major boreal forest components were determined for a 821 km ?? 619 km region, ranging from the southern grasslands-boreal forest ecotone to the northern boreal transitional forest. The boreal wetlands (mostly lowland black spruce, tamarack, mosses, fens, and bogs) occupied approximately 33% of the region, while lakes accounted for another 13%. Upland mixed coniferous-deciduous forests represented 23% of the ecosystem. A SW-NE productivity gradient across the region is manifested by three levels of tree stand density for both the boreal wetland conifer and the mixed forest classes, which are generally aligned with isopleths of regional growing degree days. Approximately 30% of the region was directly affected by fire disturbance within the preceding 30-35 years, especially in the Canadian Shield Zone where large fire-regeneration patterns contribute to the heterogeneous boreal landscape. Intercomparisons with land cover classifications derived from 30-m Landsat Thematic Mapper (TM) data provided important insights into the relative accuracy of the 1 km AVHRR land cover classification. Primarily due to the multitemporal NDVI image compositing process, the 1 km AVHRR land cover classes have an effective spatial resolution in the 3-4 km range; therefore fens, bogs, small water bodies, and small patches of dry jack pine cannot be resolved within the wet conifer mosaic. Major differences in the 1-km AVHRR and 30-m Landsat TM-derived land cover classes are most likely due to differences in the spatial resolution of the data sets. In general, the 1 km AVHRR land cover classes are vegetation mosaics consisting of mixed combinations of the Landsat classes. Detailed mapping of the global boreal forest with this approach will benefit from algorithms for cloud screening and to atmospherically correct reflectance data for both aerosol and water vapor effects. We believe that this 1 km AVHRR land cover analysis provides new and useful information for regional water, energy, carbon, and trace gases studies in BOREAS, especially given the significant spatial variability in land cover type and associated biophysical land cover parameters (e.g., albedo, leaf area index, FPAR, and surface roughness). Multiresolution land cover comparisons (30 m, 1 km, and 100 km grid cells) also illustrated how heterogeneous landscape patterns are represented in land cover maps with differing spatial scales and provided insights on the requirements and challenges for parameterizing landscape heterogeneity as part of land surface process research.

Journal of Geophysical Research D: Atmospheres↗

USGS2014

Trade-offs in experimental designs for estimating post-release mortality in containment studies

Estimates of post-release mortality (PRM) facilitate accounting for unintended deaths from fishery activities and contribute to development of fishery regulations and harvest quotas. The most popular method for estimating PRM employs containers for comparing control and treatment fish, yet guidance for experimental design of PRM studies with containers is lacking. We used simulations to evaluate trade-offs in the number of containers (replicates) employed versus the number of fish-per container when estimating tagging mortality. We also investigated effects of control fish survival and how among container variation in survival affects the ability to detect additive mortality. Simulations revealed that high experimental effort was required when: (1) additive treatment mortality was small, (2) control fish mortality was non-negligible, and (3) among container variability in control fish mortality exceeded 10% of the mean. We provided programming code to allow investigators to compare alternative designs for their individual scenarios and expose trade-offs among experimental design options. Results from our simulations and simulation code will help investigators develop efficient PRM experimental designs for precise mortality assessment.

Fisheries Research↗

USGS2022

Genome-wide genetic diversity may help identify fine-scale genetic structure among lake whitefish spawning groups in Lake Erie

In Lake Erie, lake whitefish Coregonus clupeaformis supported lucrative fisheries before populations were decimated by overfishing and water quality degradation. In recent years, there has been a renewed interest in lake whitefish and management of the fishery they support. Lake whitefish spawn on several reefs throughout Lake Erie, but the relative recruitment dynamics and contributions of spawning groups to the fishery are not well understood. Modern high-throughput sequencing approaches offer new opportunities to census population diversity and to identify subtle differences among closely related populations. We used high-throughput sequencing data to evaluate the genetic structure and diversity of lake whitefish collected opportunistically across broad spatial scales in Lake Erie. Using RAD-capture (Rapture), we sequenced and genotyped individuals (N = 88) from the west, central, and east basin of Lake Erie at 120,268 single nucleotide polymorphisms (SNPs). Lake whitefish from Niagara and Crib Reefs (west basin) diverged from the three collections. Interestingly, these were the only lake whitefish collected during the act of spawning (late November), and all other fish were collected pre-spawn (August-early November). These results suggest that some lake whitefish spawning reefs may be reproductively isolated, though definition of these groups into stocks will require more intentional sampling during the act of spawning.

Michigan, New York, Ohio, Ontario, Pennsylvania↗

USGS2012

Source characteristics of the Loma Prieta, California, Earthquake of October 18, 1989 from global digital seismic data

Displacement, velocity and acceleration records of P and SH body waves recorded at teleseismic distances are analysed to determine the static and dynamic source parameters of the Loma Prieta, California earthquake of October 18, 1989 ( m b 6.6, M s 7.1). Three distinct bursts of energy corresponding to three subevents can be recognized in most records. The displacement waveforms indicate that the first subevent contributes negligible moment while the largest releases of moment and energy are controlled by the second and third subevents. The second and third subevents are located north and south of the initial nucleation. A fourth small subevent needed to model later features of the P waveforms suggests that slow slip continued after the major releases of energy occurred. The waveforms are fit with a fault plane solution having strike 130°, dip 65° and slip 140° for all the subevents. The focal depths of the two major subevents are 16 and 12 km, and their asperity radii are 4.0 and 6.0 km, respectively. The seismic moment, M 0 , is 2.2×10 26 dyne-cm. From spectral analysis of teleseismic velocity, the radiated energy, E s , is estimated to be 1.1×10 22 dyne-cm, implying an apparent stress of 15 bars. From the high-frequency level of the teleseismic acceleration spectrum and a rupture area of 440 km 2 , we derive a dynamic stress drop of 51 bars.

California↗

USGS2012

Strain accumulation across the Denali fault in the Delta River canyon, Alaska

Deformation along the Denali fault in the Delta River canyon was determined from geodetic surveys in 1941/1942, 1970, 1975, and 1979. The data were best for the 1975–1979 interval; in that period the average strain accumulation was essentially pure right lateral shear at a rate of 0.6 ± 0.1 μrad/a (a is years) (engineering shear) across a vertical plane striking N87°E. The plane of maximum shear is rotated about 30° counterclockwise from the local strike of the Denali fault but closely coincides with the strike of a major linear segment of the fault that begins 50 km farther west. The deformation between 1941/1942 and 1970 is consistent with a similar rate of strain accumulation if one removes the coseismic strain step contributed by the 1964 Alaska earthquake. The 1970–1975 deformation is poorly defined owing to uncertainties in the 1970 survey, but the strain accumulation during that period is certainly much less than during the 1975–1979 interval. The 1975–1979 strain accumulation is interpreted by means of a dislocation model which suggests that the Denali fault in the vicinity of the Delta River Canyon behaves as a leaky transform fault (i.e., a source of spreading as well as lateral slip). The block south of the Denali fault appears to be moving westward (parallel to the strike of the Denali fault west of the 147th meridian) at the rate of about 20 mm/a relative to the North American plate. Because the linear segment of the Denali fault east of the 147th meridian (along which the geodetic network is located) strikes N63°W, accommodation of the westward motion of the southern block requires some spreading within the fault zone as well as right lateral slip on the fault.

Journal of Geophysical Research Solid Earth↗

USGS2008

Selected Water- and Sediment-Quality, Aquatic Biology, and Mine-Waste Data from the Ely Copper Mine Superfund Site, Vershire, VT, 1998-2007

The data contained in this report are a compilation of selected water- and sediment-quality, aquatic biology, and mine-waste data collected at the Ely Copper Mine Superfund site in Vershire, VT, from August 1998 through May 2007. The Ely Copper Mine Superfund site is in eastern, central Vermont (fig. 1) within the Vermont Copper Belt (Hammarstrom and others, 2001). The Ely Copper Mine site was placed on the U.S. Environmental Protection Agency (USEPA) National Priorities List in 2001. Previous investigations conducted at the site documented that the mine is contributing metals and highly acidic waters to local streams (Hammarstrom and others, 2001; Holmes and others, 2002; Piatak and others, 2003, 2004, and 2006). The U.S. Geological Survey (USGS), in cooperation with the USEPA, compiled selected data from previous investigations into uniform datasets that will be used to help characterize the extent of contamination at the mine. The data may be used to determine the magnitude of biological impacts from the contamination and in the development of remediation activities. This report contains analytical data for samples collected from 98 stream locations, 6 pond locations, 21 surface-water seeps, and 29 mine-waste locations. The 98 stream locations are within 3 streams and their tributaries. Ely Brook flows directly through the Ely Copper Mine then into Schoolhouse Brook (fig. 2), which joins the Ompompanoosuc River (fig. 1). The six pond locations are along Ely Brook Tributary 2 (fig. 2). The surface-water seeps and mine-waste locations are near the headwaters of Ely Brook (fig. 2 and fig. 3). The datasets 'Site_Directory' and 'Coordinates' contain specific information about each of the sample locations including stream name, number of meters from the mouth of stream, geographic coordinates, types of samples collected (matrix of sample), and the figure on which the sample location is depicted. Data have been collected at the Ely Copper Mine Superfund site by the USEPA, the Vermont Department of Environmental Conservation (VTDEC), and the USGS. Data also have been collected on behalf of USEPA by the following agencies: Arthur D. Little Incorporated (ADL), U.S. Army Cold Region Research and Engineering Laboratory (CRREL), URS Corporation (URS), USEPA, and USGS. These data provide information about the aquatic communities and their habitats, including chemical analyses of surface water, pore water, sediments, and fish tissue; assessments of macroinvertebrate and fish assemblages; physical characteristics of sediments; and chemical analyses of soil and soil leachate collected in and around the piles of mine waste.

Data Series↗

USGS2016

Influence of vertical and lateral heat transfer on permafrost thaw, peatland landscape transition, and groundwater flow

Recent climate change has reduced the spatial extent and thickness of permafrost in many discontinuous permafrost regions. Rapid permafrost thaw is producing distinct landscape changes in the Taiga Plains of the Northwest Territories, Canada. As permafrost bodies underlying forested peat plateaus shrink, the landscape slowly transitions into unforested wetlands. The expansion of wetlands has enhanced the hydrologic connectivity of many watersheds via new surface and near-surface flow paths, and increased streamflow has been observed. Furthermore, the decrease in forested peat plateaus results in a net loss of boreal forest and associated ecosystems. This study investigates fundamental processes that contribute to permafrost thaw by comparing observed and simulated thaw development and landscape transition of a peat plateau-wetland complex in the Northwest Territories, Canada from 1970 to 2012. Measured climate data are first used to drive surface energy balance simulations for the wetland and peat plateau. Near-surface soil temperatures simulated in the surface energy balance model are then applied as the upper boundary condition to a three-dimensional model of subsurface water flow and coupled energy transport with freeze-thaw. Simulation results demonstrate that lateral heat transfer, which is not considered in many permafrost models, can influence permafrost thaw rates. Furthermore, the simulations indicate that landscape evolution arising from permafrost thaw acts as a positive feedback mechanism that increases the energy absorbed at the land surface and produces additional permafrost thaw. The modeling results also demonstrate that flow rates in local groundwater flow systems may be enhanced by the degradation of isolated permafrost bodies.

Northwest Territories↗

USGS2007

Questa Baseline and Pre-Mining Ground-Water Quality Investigation. 24. Seismic Refraction Tomography for Volume Analysis of Saturated Alluvium in the Straight Creek Drainage and Its Confluence With Red River, Taos County, New Mexico

As part of a research effort directed by the New Mexico Environment Department to determine pre-mining water quality of the Red River at a molybdenum mining site in northern New Mexico, we used seismic refraction tomography to create subsurface compressional-wave velocity images along six lines that crossed the Straight Creek drainage and three that crossed the valley of Red River. Field work was performed in June 2002 (lines 1-4) and September 2003 (lines 5-9). We interpreted the images to determine depths to the water table and to the top of bedrock. Depths to water and bedrock in boreholes near the lines correlate well with our interpretations based on seismic data. In general, the images suggest that the alluvium in this area has a trapezoidal cross section. Using a U.S. Geological Survey digital elevation model grid of surface elevations of this region and the interpreted elevations to water table and bedrock obtained from the seismic data, we generated new models of the shape of the buried bedrock surface and the water table through surface interpolation and extrapolation. Then, using elevation differences between the two grids, we calculated volumes of dry and wet alluvium in the two drainages. The Red River alluvium is about 51 percent saturated, whereas the much smaller volume of alluvium in the tributary Straight Creek is only about 18 percent saturated. When combined with average ground-water velocity values, the information we present can be used to determine discharge of Straight Creek into Red River relative to the total discharge of Red River moving past Straight Creek. This information will contribute to more accurate models of ground-water flow, which are needed to determine the pre-mining water quality in the Red River.

Scientific Investigations Report↗

USGS2021

The contribution of land cover change to the decline of honey yields in the Northern Great Plains

Decreased availability of forage, as well as increased pesticide exposure, are important factors in the decline of honey bee health. Here, we isolate land cover transitions and their effect on honey production at 160 commercial apiaries in the Northern Great Plains. We found that land cover changes from 2008 to 2012 caused an annual decline in honey yields of 0.9% in the study area. Transitions from grassland to soybean (but not corn) were particularly detrimental to honey yields, potentially due to bee contact with pesticides within and around agricultural fields. When our results are applied to known apiary locations across all of North Dakota (U.S.A.), we estimate a 2.5% (1.6 million USD) decline in 2012 honey yields due to land cover changes occurring between 2008 and 2012. Even when controlling for changes in land cover, we found that on average colonies in the study area experienced a 14% annual decline in honey yields. We discuss possible explanations for these non-land-cover-related honey yield declines, including changing economic conditions (e.g. pollination services), changes in land management (e.g. pesticides), and increases in pests or diseases.

South Dakota↗

USGS1997

Comparing nocturnal eddy covariance measurements to estimates of ecosystem respiration made by scaling chamber measurements at six coniferous boreal sites

During the growing season, nighttime ecosystem respiration emits 30–100% of the daytime net photosynthetic uptake of carbon, and therefore measurements of rates and understanding of its control by the environment are important for understanding net ecosystem exchange. Ecosystem respiration can be measured at night by eddy covariance methods, but the data may not be reliable because of low turbulence or other methodological problems. We used relationships between woody tissue, foliage, and soil respiration rates and temperature, with temperature records collected on site to estimate ecosystem respiration rates at six coniferous BOREAS sites at half-hour or 1-hour intervals, and then compared these estimates to nocturnal measurements of CO 2 exchange by eddy covariance. Soil surface respiration was the largest source of CO 2 at all sites (48–71%), and foliar respiration made a large contribution to ecosystem respiration at all sites (25–43%). Woody tissue respiration contributed only 5–15% to ecosystem respiration. We estimated error for the scaled chamber predictions of ecosystem respiration by using the uncertainty associated with each respiration parameter and respiring biomass value. There was substantial uncertainty in estimates of foliar and soil respiration because of the spatial variability of specific respiration rates. In addition, more attention needs to be paid to estimating foliar respiration during the early part of the growing season, when new foliage is growing, and to determining seasonal trends of soil surface respiration. Nocturnal eddy covariance measurements were poorly correlated to scaled chamber estimates of ecosystem respiration ( r 2 =0.06–0.27) and were consistently lower than scaled chamber predictions (by 27% on average for the six sites). The bias in eddy covariance estimates of ecosystem respiration will alter estimates of gross assimilation in the light and of net ecosystem exchange rates over extended periods.

Journal of Geophysical Research D: Atmospheres↗

USGS2020

Predicting multi-species foraging hotspots for marine turtles in the Gulf of Mexico

Quantifying the distribution of animals and identifying underlying characteristics that define suitable habitat are essential for effective conservation of free-ranging species. Prioritizing areas for conservation is important in managing a geographic extent that has a high level of disturbance and limited conservation resources. We examined the potential use of a species distribution model ensemble for multi-species conservation in marine habitats. Using satellite telemetry locations during foraging as input data, and ensemble ecological niche models, we predicted foraging areas for 2 nesting marine turtle species within the Gulf of Mexico (GoM): Kemp’s ridley Lepidochelys kempii (n = 63) and loggerhead Caretta caretta (n = 63). We considered 7 geophysical, biological, and climatic variables and compared contributing factors for each species’ foraging habitat selection. For both species, predicted suitable foraging habitats encompassed large areas along the GoM coast, but only intersected with each other in relatively small areas. Highly parameterized models resulted in overall greater fits, suggesting that multiple factors influence habitat selection by these species. Model validation results were mixed: cross-validation resulted in high prediction accuracy for both species, but an evaluation against independent data resulted in a low omission rate (5%) for Kemp’s ridleys and a high omission rate (72%) for loggerheads. The relatively small intersection of model-predicted foraging areas for these 2 species within the study area may indicate possible niche differentiations. The high omission rate for loggerheads indicates our samples likely underrepresent the population and illustrates the challenges in predicting suitable foraging extents for species that make dynamic movements and have greater individual variability.

Gulf of Mexico↗

USGS2025

Population and outmigration characteristics of juvenile Bull Trout in a montane ecosystem

Bull Trout Salvelinus confluentus is a federally threatened species in the conterminous United States. Although some populations are stable or increasing, Bull Trout in the United States Fish and Wildlife Service's designated Coeur d'Alene Core Area in Idaho have experienced substantial declines in abundance. Today, the remaining extant population in the Coeur d'Alene Core Area returns to the headwaters of the St. Joe River to spawn. The population has been monitored annually since 1992 using spawning ground surveys, but little is known about early life stages in the system. The objective of our research was to evaluate the distribution and abundance, age and size structure, habitat associations, and outmigration characteristics of juvenile Bull Trout in the upper St. Joe River basin. In 2022–2023, we sampled 200 stream reaches on the mainstem St. Joe River and four tributaries (Heller, Medicine, Sherlock, and Wisdom creeks). We sampled 1,529 Bull Trout varying in length from 29−257 mm in total length (TL; mean ± SD; 108 ± 44 mm). Population estimates suggested there were 1,841 (95% CI = 1,188−2,494) juvenile Bull Trout in the study area in 2022 and 2,388 (1,646−3,130) in 2023. Regression models indicated that abundance was positively related to canopy cover, amount of large substrate, amount of large woody debris, and amount of gravel, and negatively related to water temperature. We tagged 1,142 fish with passive integrated transponders (PIT) and detected 163 (14%) of these fish using a stationary tag array that was operational during June or July through October. Peak autumn outmigration occurred in October of both sampling years. Of the fish that were detected moving, age varied from 1−4 years, but age-1 and age-2 fish were more commonly detected moving downstream compared to other age classes. This study provides important information on the ecology of juvenile Bull Trout that can be used to guide conservation and recovery efforts in montane ecosystems. Furthermore, juvenile Bull Trout in the upper St. Joe River basin were present at similar densities and experienced growth rates similar to more robust adfluvial populations (e.g., Lake Pend Oreille, Idaho), thereby indicating that factors contributing to the low abundance of adults are not likely occurring in the headwaters of the St. Joe River. Thus, conservation efforts may be more successful if they are focused on the migration corridor and Coeur d'Alene Lake.

Idaho↗