U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you're on a federal government site.


The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Publications recently added to the Pubs Warehouse

(500 records max)

NDVI exhibits mixed success in predicting spatiotemporal variation in caribou summer forage quality and quantity

Released October 17, 2018 11:06 EST

2018, Ecosphere (9) 1-19

Heather E. Johnson, David D. Gustine, Trevor S. Golden, Layne G. Adams, Lincoln S. Parrett, Elizabeth A. Lenart, Perry S. Barboza

The satellite‐derived Normalized Difference Vegetation Index (NDVI) is commonly used by researchers and managers to represent ungulate forage conditions in landscapes across the globe, despite limited information about how it compares to empirical measurements of forage quality and quantity. The application of NDVI as a forage metric is particularly appealing for studying migratory caribou (Rangifer tarandus) in remote Arctic ecosystems, where field assessments are logistically and financially prohibitive, and climate‐mediated changes in vegetation have been hypothesized to influence population declines. To determine the utility of NDVI for adequately representing caribou forage conditions, we compared NDVI derived from Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery to empirical measures of caribou forage biomass, nitrogen, digestible nitrogen, and digestible energy within the summer range of the Central Arctic Caribou Herd on the North Slope of Alaska. Specifically, we determined the strength of forage–NDVI relationships at the start of the growing season and across the summer, assessed the efficacy of NDVI variables for modeling spatiotemporal variation in field measurements of different forage components, and used long‐term MODIS data to estimate temporal changes in forage between 2000 and 2016. We found that NDVI values were weakly correlated with caribou forage quality at the start of the growing season and throughout the summer. Although linear models of forage–NDVI relationships performed poorly, NDVI variables (NDVI and the number of days from when NDVI reached its maximum value) were useful for modeling spatiotemporal variation in empirical measurements of forage components across the growing season, but only when we incorporated nonlinear forage–NDVI relationships and other habitat covariates. Phenological advances in the date of peak NDVI were associated with significant changes in forage conditions, particularly nitrogen, which exhibited earlier seasonal declines. Using long‐term MODIS data, predicted values of forage nitrogen declined between 2000 and 2016, driven by exceedingly low values in 2014 and 2015. Given our results, we caution the application of NDVI as a general (linear) proxy of caribou forage conditions across the growing season, and encourage practitioners to use NDVI variables to model spatiotemporal variation in specific forage conditions from empirical field data, accounting for nonlinear forage–NDVI relationships.

Evaluation of biodiversity data portals based on requirement analysis

Released October 17, 2018 10:56 EST

2018, Ecological Informatics (48) 215-225

Pedro Luiz Pizzigatti Corrêa, André Filipe de Moraes Batista, Daniel Lins da Silva, Ronaldo Soares Rodrigues, Mike Frame, Marcelo Morandini, Silvio Stanzani, Fernando Correa

In recent years, concern about the misuse of natural resources has been increasing. It is essential to know in detail the biodiversity of an ecosystem to understand and analyze the impact of human activities on nature, as well as to promote the economic growth of a country. To achieve these goals, public and private institutions are aggregating and sharing biological data around the world by means of biodiversity data portals. The main purpose of those portals is to provide a set of tools that help users and institutions catalog, analyze, and publish raw data about different species in a manner that is open and freely available to any interested party. Normally the process of choosing the best software solution is not straightforward. This paper proposes a methodology to evaluate a collection of data portals to establish a clear and consistent selection process that analyzes a collection of requirements and research purposes. The proposed approach is based on three strategies: the use of software engineering techniques to identify the desired group of features to be available in the data portal; the application of the Kano Satisfaction Model to score each requirement according to a preset weight of importance; and the use of tree-maps to visualize the requirements based on their implementation priority, to establish a portal deployment road-map. The proposed methodology is broadly applicable to portal analyses for many communities of practice.

Determination of representative uranium and selenium concentrations from groundwater, 2016, Homestake Mining Company Superfund site, Milan, New Mexico

Released October 17, 2018 08:30 EST

2018, Open-File Report 2018-1055

Philip T. Harte, Johanna M. Blake, Kent D. Becher

In 2016, the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, collected data on isotopes, age dating, and geochemistry including aqueous uranium concentrations of samples from 20 locations in the vicinity of the Homestake Mining Company Superfund site near Milan, New Mexico. The 20 sampled locations include 19 groundwater wells and 1 treatment plant for water used for injection into aquifers. At 6 of the 19 wells, multiple samples were collected by several different sampling methods, including passive, micropurge, and volumetric methods.

Aqueous uranium concentrations were adjusted on the basis of comparisons between three sampling methods (called sample adjustments). These adjustments were specific to passive sample results because they underestimated uranium concentrations compared with results from purge samples (micropurge and volumetric). Sample adjustments were also made on aqueous selenium concentrations from previously published data for passive sampler results following a similar procedure.

Aqueous uranium concentrations in dissolved and total form were adjusted from the original analytical values (called laboratory analytical adjustments) on the basis of a rigorous comparison to several external tests, including reruns and analysis by a different laboratory after accuracy issues were identified in data from the original laboratory. The original laboratory analytical results were found to be two to five times greater than historical concentrations at the same locations, which prompted further evaluation, as described in this report.

Three-dimensional seismic characterization of karst in the Floridan aquifer system, southeastern Miami-Dade County, Florida

Released October 16, 2018 13:51 EST

2018, Scientific Investigations Report 2018-5117

Kevin J. Cunningham, Joann F. Dixon, Richard L. Westcott, Sean Norgard, Cameron Walker

Two three-dimensional seismic surveys totaling 3.4 square miles were acquired in southeastern Miami-Dade County during 2015 as part of an ongoing broad regional investigation by the U.S. Geological Survey, in cooperation with the Miami-Dade Water and Sewer Department, that includes mapping and karst characterization of the Floridan aquifer system in southeastern Florida. Twenty columniform seismic-sag structures were identified in the three-dimensional seismic data acquired at the South Miami Heights study area in Miami-Dade County, Florida. The seismic-sag structures are commonly composed of a lower and upper seismic facies, where the lower facies is interpreted to be a high permeability column-shaped volume of intense karstification composed of faults, fractures, and collapsed caves, and the upper facies is interpreted to be a lower permeability column-shaped volume composed of sagging suprastratal reflections having little or no faulting, fracturing, or caves. The seismic-sag structures are columniform karst-collapse structures that formed by cave collapse or stoping (upward void migration caused primarily by the mechanical process of ceiling collapse) or both in carbonate rocks of the early Eocene Oldsmar Formation and in some cases in the lowermost part of the middle Eocene Avon Park Formation. Columniform subsidence and sagging of overburden succeeded karst collapse in the lower part of the structures. At the study area, there may be relatively higher potential for the columniform karst-collapse structures to provide cross-formational fluid migration upward from the Boulder Zone into the lower part of middle confining unit 2 as compared to a lower potential for cross-formational fluid migration from the upper part of middle confining unit 2 upward to the Upper Floridan aquifer.

Inventory of lowland-breeding birds on the Alaska Peninsula

Released October 16, 2018 12:10 EST

2018, Journal of Fish and Wildlife Management

Susan E. Savage, Lee Tibbitts, Kristin Sesser, Robb S.A. Kaler

During summers of 2004-2007, we conducted the first systematic inventory of birds in the lowlands (areas {less than or equal to}100 m above sea level) of the Alaska Peninsula to determine their breeding distributions and habitat associations in this remote region. We used a stratified random survey design to allocate sample plots by elevation and land cover with a preference for wetland cover types used by shorebirds, a group of particular interest to land managers. We surveyed all birds by conducting 10-min counts at 792 points across 52, 5-km x 5-km sample plots distributed from south of the Naknek River (58.70°N,157.00°W) to north of Port Moller (56.00°N,160.52°W). We detected 95 bird species including 19 species of shorebirds and 34 species (36% of total) considered at the time to be of conservation concern for the land managers in the region. The most numerous shorebirds on point counts were dunlin Calidris alpina, short-billed dowitcher Limnodromus griseus, and Wilson's snipe Gallinago delicata. The breeding-season endemic marbled godwit Limosa fedoa beringiae was found at 20 plots within a 3,000 km2 area from north of Ugashik Bay to just north of Port Heiden and east to the headwaters of the Dog Salmon and Ugashik rivers. The most abundant passerines on point counts were American tree sparrow Spizelloides arborea, Lapland longspur Calcarius lapponicus, and savannah sparrow Passerculus sandwichensis. Sandhill crane Antigone canadensis, glaucous-winged gull Larus glaucescens, and greater scaup Athya marila were also relatively abundant. We categorized habitat associations for 30 common species and found that lowland herbaceous vegetation supported wetland-focused species including sandhill crane, marbled godwit, short-billed dowitcher, and dunlin whereas dwarf-shrub ericaceous vegetation supported tundra-associated species such as willow ptarmigan Lagopus lagopus, rock sandpiper Calidris ptilocnemis, and American pipit Anthus rubescens. Tall shrub vegetation was important to several species of warblers and sparrows, as well as one species of shorebird (greater yellowlegs Tringa melanoleuca). We found that point counts augmented with incidental observations provided an almost complete inventory of lowland-breeding species on the study area. These data form a baseline to monitor any future changes in bird distribution and abundance on the Alaska Peninsula.

Museum metabarcoding: a novel method revealing gut helminth communities of small mammals across space and time

Released October 16, 2018 12:05 EST

2018, International Journal for Parasitology

Stephen E. Greiman, Joseph A. Cook, Vasyl V. Tkach, Eric P. Hoberg, Damian M. Menning, Andrew G. Hope, Sarah A. Sonsthagen, Sandra L. Talbot

Natural history collections spanning multiple decades provide fundamental historical baselines to measure and understand changing biodiversity. New technologies such as next generation DNA sequencing (NGS) have considerably increased the potential of museum specimens to address significant questions regarding the impact of environmental changes on host and parasite/pathogen dynamics. We developed a new technique to identify intestinal helminth parasites and applied it to shrews (Eulipotyphla: Soricidae) because they are ubiquitous, occupy diverse habitats, and host a diverse and abundant parasite fauna. Notably, we included museum specimens preserved in various ways to explore the efficacy of using metabarcoding analyses that may enable identification of helminth symbiont communities from historical archives. We successfully sequenced the parasite communities (using 12S mtDNA, 16S mtDNA, 28S rDNA) of 23 whole gastrointestinal (GI) tracts. All GI tracts were obtained from the Museum of Southwestern Biology (MSB), USA, and from recent field collections, varying both in time since fixation (ranging from 4 months to 16 years) and preservation method (70% or 95% ethanol stored at room temperature, or flash frozen in liquid nitrogen and stored at -80°C). Our proof of concept demonstrates the feasibility of applying NGS techniques to authoritatively identify the parasite/pathogen communities within whole GI tracts from museum specimens of varying age and fixation, and the value of future preservation of host-associated whole GI tracts in public research archives. This powerful approach facilitates future comparative examinations of the distributions and interactions among multiple associated groups of organisms through time and space.

Fuelling conditions at staging sites can mitigate Arctic warming effects in a migratory bird

Released October 15, 2018 15:51 EST

2018, Nature Communications (9) 1-10

Eldar Rakhimberdiev, Sjoerd Duijns, Julia Karagicheva, Cornelis J. Camphuysen, Anne Dekinga, Rob Dekker, Anatoly Gavrilov, Job ten Horn, Joop Jukema, Anatoly Saveliev, Mikhail Soloviev, Lee Tibbitts, Jan A. van Gils, Theunis Piersma, VRS Castricum

Under climate warming, migratory birds should align reproduction dates with advancing plant and arthropod phenology. To arrive on the breeding grounds earlier, migrants may speed up spring migration by curtailing the time spent en route, possibly at the cost of decreased survival rates. Based on a decades-long series of observations along an entire flyway, we show that when refuelling time is limited, variation in food abundance in the spring staging area affects fitness. Bar-tailed godwits migrating from West Africa to the Siberian Arctic reduce refuelling time at their European staging site and thus maintain a close match between breeding and tundra phenology. Annual survival probability decreases with shorter refuelling times, but correlates positively with refuelling rate, which in turn is correlated with food abundance in the staging area. This chain of effects implies that conditions in the temperate zone determine the ability of godwits to cope with climate-related changes in the Arctic.

Novel ecological and climatic conditions drive rapid adaptation in invasive Florida Burmese pythons

Released October 15, 2018 15:46 EST

2018, Molecular Ecology

Daren C. Card, Blair W. Perry, Richard H. Adams, Drew R. Schield, Acacia S. Young, Audra L. Andrew, Tereza Jezkova, Giulia I.M. Pasquesi, Nicole R. Hales, Matthew R. Walsh, Michael R. Rochford, Frank J. Mazzotti, Kristen M. Hart, Margaret Hunter, Todd A. Castoe

Invasive species provide powerful in situ experimental systems for studying evolution in response to selective pressures in novel habitats. While research has shown that phenotypic evolution can occur rapidly in nature, few examples exist of genome‐wide adaptation on short ‘ecological’ timescales. Burmese pythons (Python molurus bivittatus) have become a successful and impactful invasive species in Florida over the last 30 years despite major freeze events that caused high python mortality. We sampled Florida Burmese pythons before and after a major freeze event in 2010 and found evidence for directional selection in genomic regions enriched for genes associated with thermosensation, behavior, and physiology. Several of these genes are linked to regenerative organ growth, an adaptive response that modulates organ size and function with feeding and fasting in pythons. Independent histological and functional genomic datasets provide additional layers of support for a contemporary shift in invasive Burmese python physiology. In the Florida population, a shift towards maintaining an active digestive system may be driven by the fitness benefits of maintaining higher metabolic rates and body temperature during freeze events. Our results suggest that a synergistic interaction between ecological and climatic selection pressures have driven adaptation in Florida Burmese pythons, demonstrating the often‐overlooked potential of rapid adaptation to influence the success of invasive species.

Interseismic ground deformation and fault slip rates in the greater San Francisco Bay Area from two decades of space geodetic data

Released October 15, 2018 15:38 EST

2018, Journal of Geophysical Research B: Solid Earth

Wenbin Xu, Songbo Wu, Kathryn Materna, Robert Nadeau, Michael Floyd, Gareth J. Funning, Estelle Chaussard, Christopher W. Johnson, Jessica R. Murray, Xiaoling Ding, Roland Burgmann

Songbo Wu, Robert Nadeau, Xiaoling Ding, editor(s)

The detailed spatial variations of strain accumulation and creep on major faults in the northern San Francisco Bay Area (North Bay), which are important for seismic potential and evaluation of natural hazards, remain poorly understood. Here we combine interferometric synthetic aperture radar data from the ERS‐1/2 and Envisat satellites between 1992 and 2010 with continuous and campaign GPS data to obtain a high spatial and temporal coverage of ground deformation of the North Bay. The SAR data from both ascending and descending orbits are combined to separate horizontal and vertical components of the deformation. We jointly invert the horizontal component of the mean velocities derived from these data to infer the deep strike‐slip rates on major locked faults. We use the estimated deep rates to simulate the long‐wavelength deformation due to interseismic elastic strain accumulation along these locked faults. After removing the long‐wavelength signal from the InSAR horizontal mean velocity field, we estimate fault‐parallel surface creep rates of up to 2 mm/year along the central section of the Rodgers Creek fault and surface creep rates ranging between 2 and 4 mm/year along the Concord fault. No surface creep is geodetically resolved along the West Napa and Green Valley fault zones. We identified characteristically repeating earthquakes on the Rodgers Creek fault, the West Napa fault, the Green Valley fault, and the Concord fault. Nontectonic deformation in the Geysers geothermal field and in Late Cenozoic basins (Rohnert Park and Sonoma basins) are also observed, likely due to hydrological and sediment‐compaction processes, respectively.

Effects of persistent energy-related brine contamination on amphibian abundance in national wildlife refuge wetlands

Released October 15, 2018 15:32 EST

2018, Biological Conservation (228) 36-43

Blake R. Hossack, Kelly L. Smalling, Chauncey W. Anderson, Todd M. Preston, Isabelle M. Cozzarelli, R. Ken Honeycutt

To inform sustainable energy development, it is important to understand the ecological effects of historical and current production practices and the persistence of those effects. The Williston Basin is one of North America's largest oil production areas and overlaps the Prairie Pothole Region, an area densely populated with wetlands that provide important wildlife habitat. Although historical disposal practices that released chloride-rich waters (brines) produced during oil extraction into the environment are no longer used, brine spills still occur frequently. We sampled 33 wetlands for three amphibian species in Montana and North Dakota during 2015–2017, primarily on National Wildlife Refuges, and used N-mixture models to determine how abundance varied with evidence of brine contamination. To provide insight into effects of historical versus contemporary contamination, we also estimated the association of well density and age with water quality and amphibian abundance. Abundance of boreal chorus frog (Pseudacris maculata) larvae declined most rapidly in response to increased chloride (range: 0.04–17,500 mg/L), followed by the northern leopard frog (Lithobates [Ranapipiens) and barred tiger salamander (Ambystoma mavortium). Water quality and population- and community-level abundance of amphibians were more strongly related to nearby wells (≤800 m) installed before 1982 than to wells installed since 1982. These results suggest historical brine management practices were the primary driver of contamination and reduced amphibian abundance in wetlands we sampled, reflecting multi-decadal ecological effects. These persistent effects also underscore the critical need for tools to restore landscapes affected by brine contamination.

Compilation and assessment of resource values and hazards to inform transportation planning and associated land-use planning

Released October 15, 2018 15:15 EST

2018, Scientific Investigations Report 2018-5039

Daniel Manier, Michael O'Donnell

Land-use planning has an important role in local, regional, State, and Federal land management, and planning efforts can benefit from consistent, spatially explicit information that can help guide priorities and decisions. The credibility and relevance of information used to inform planning activities depends on the availability of consistent information about the resources and values of interest or concern within the planning area. To support long-range transportation planning and other regional land-use planning efforts, the U.S. Geological Survey gathered, processed, interpreted, and compiled spatial datasets representing a wide range of information on terrestrial and aquatic ecosystem condition and importance, cultural (historical) features and places, and natural hazards. This report describes the spatial data compiled to represent natural landscape conditions (including social, cultural, and natural attributes) to estimate the potential importance of lands for wildlife, wild habitats, recreation, and conservation based on abundance of species, habitats, land and water conditions, and conservation designations. Abundance of resources, including the potential number of species, presence of important habitats and protected areas, and proximity to particular features or habitats, indicates the potential sensitivity of the natural landscape to land use, especially transportation networks. The source data, derived indices, and the methods for processing these data are described in this final report. The datasets referenced in the report are available from the U.S. Geological Survey (https://www.sciencebase.gov/catalog/ and https://doi.org/10.5066/F7MW2F8W) or the Central Federal Lands Highway Division of the Office of Federal Lands Highway (https://flh.fhwa.dot.gov).

Cracking the code of biodiversity responses to past climate change

Released October 15, 2018 15:11 EST

2018, Trends in Ecology and Evolution (33) 765-776

David Nogués-Bravo, Francisco Rodríguez-Sánchez, Luisa Orsini, Erik de Boer, Roland Jansson, Helene Morlon, Damien A. Fordham, Stephen T. Jackson

How individual species and entire ecosystems will respond to future climate change are among the most pressing questions facing ecologists. Past biodiversity dynamics recorded in the paleoecological archives show a broad array of responses, yet significant knowledge gaps remain. In particular, the relative roles of evolutionary adaptation, phenotypic plasticity, and dispersal in promoting survival during times of climate change have yet to be clarified. Investigating the paleo-archives offers great opportunities to understand biodiversity responses to future climate change. In this review we discuss the mechanisms by which biodiversity responds to environmental change, and identify gaps of knowledge on the role of range shifts and tolerance. We also outline approaches at the intersection of paleoecology, genomics, experiments, and predictive models that will elucidate the processes by which species have survived past climatic changes and enhance predictions of future changes in biological diversity.

Assessing effects of nonnative crayfish on mosquito survival

Released October 15, 2018 14:59 EST

2018, Conservation Biology

Gary M. Bucciarelli, Daniel Suh, Avery Davis Lamb, Dave Roberts, Debra Sharpton, H. Bradley Shaffer, Robert N. Fisher, Lee B. Kats

Introductions of nonnative predators often reduce biodiversity and affect natural predator–prey relationships and may increase the abundance of potential disease vectors (e.g., mosquitoes) indirectly through competition or predation cascades. The Santa Monica Mountains (California, U.S.A.), situated in a global biodiversity hotspot, is an area of conservation concern due to climate change, urbanization, and the introduction of nonnative species. We examined the effect of nonnative crayfish (Procambarus clarkii) on an existing native predator, dragonfly nymphs (Aeshna sp.), and their mosquito larvae (Anopheles sp.) prey. We used laboratory experiments to compare the predation efficiency of both predators, separately and together, and field data on counts of dragonfly nymphs and mosquito larvae sampled from 13 local streams. We predicted a lower predation efficiency of crayfish compared with native dragonfly nymphs and a reduced predation efficiency of dragonfly nymphs in the presence of crayfish. Dragonfly nymphs were an order of magnitude more efficient predators than crayfish, and dragonfly nymph predation efficiency was reduced in the presence of crayfish. Field count data showed that populations of dragonfly nymphs and mosquito larvae were strongly correlated with crayfish presence in streams, such that sites with crayfish tended to have fewer dragonfly nymphs and more mosquito larvae. Under natural conditions, it is likely that crayfish reduce the abundance of dragonfly nymphs and their predation efficiency and thereby, directly and indirectly, lead to higher mosquito populations and a loss of ecosystem services related to disease vector control.

Groundwater-level, groundwater-temperature, and barometric-pressure data, July 2017 to February 2018, Hālawa Area, Oʻahu, Hawaiʻi

Released October 15, 2018 12:39 EST

2018, Open-File Report 2018-1147

Jackson N. Mitchell, Delwyn S. Oki

The Red Hill Bulk Fuel Storage Facility, operated by the U.S. Navy and located in the Hālawa area, Oʻahu, Hawaiʻi, includes 20 underground storage tanks that can hold a total of 250 million gallons of fuel. In January 2014, the U.S. Navy notified the Hawaiʻi Department of Health and U.S. Environmental Protection Agency of release of an estimated 27,000 gallons of fuel from the Red Hill Bulk Fuel Storage Facility. In response to past and potential future fuel releases, data are needed to evaluate groundwater flow in the surrounding area. During July 2017–February 2018, the U.S. Geological Survey collected groundwater-level data at 24 sites near the Red Hill Bulk Fuel Storage Facility. At 14 of the 24 sites, groundwater-temperature data were also collected, and at 6 of the 24 sites, barometric-pressure data were collected. During the data-collection period, a regional aquifer test was conducted in coordination with the operators of three production wells in the area. The recorded water-level changes in response to planned withdrawal changes during December 2017–February 2018 can be used to improve understanding of the groundwater-flow system. The scope of this report is limited to a non-interpretive presentation of the data and a brief discussion of the factors affecting the water-level data.

Flood-inundation maps for the South Platte River at Fort Morgan, Colorado, 2018

Released October 15, 2018 11:15 EST

2018, Scientific Investigations Report 2018-5114

Michael S. Kohn, Thuy T. Patton

In 2017, the U.S. Geological Survey (USGS), in cooperation with the Colorado Water Conservation Board (CWCB), studied floods in the historic record to produce a library of flood-inundation maps for the South Platte River at Fort Morgan, Colorado. Digital flood-inundation maps for a 4.5-mile (7.2-kilometers) reach of the South Platte River at Fort Morgan from Morgan County Road 16 to Morgan County Road 20.5, were created. The flood-inundation maps depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the U.S. Geological Survey streamgage on the South Platte River at Fort Morgan (streamgage number 06759500).

Water-surface profiles were computed for the stream reach by means of a one-dimensional, step-backwater model. The September 15, 2013, and May 20, 2017, floods were used to calibrate the model, and the June 15, 2015, and May 29, 2017, floods were used to independently validate the model. Nine pressure transducers were deployed to record the stage at nine different locations along the reach and to document the floods of May 20 and 29, 2017, at the South Platte River at Fort Morgan streamgage.

The hydraulic model was then used to compute 16 water-surface profiles for flood stages at 1-foot (ft; 0.3-meter [m]) intervals referenced to the streamgage datum and ranging from 12 ft (3.66 m) or below bankfull to 27 ft (8.23 m), which is 1 ft (0.3 m) greater than the highest recorded water level (25.73 ft [7.84 m] on September 15, 2013) at the South Platte River at Fort Morgan streamgage during its period of record; the 2013 flood exceeds the major flood stage of 21.5 ft (6.55 m) by more than 4 ft (1.2 m), as defined by the National Weather Service.

The simulated water-surface profiles were then combined with a geographic information system digital elevation model (derived from light detection and ranging data having a 0.37-ft [0.11-m] vertical accuracy and 3.28-ft [1.00-m] horizontal resolution) to delineate the area flooded for stages ranging from 12 to 27 ft (3.66 to 8.23 m).

These flood-inundation maps, in conjunction with the real-time stage data from the USGS streamgage on the South Platte River at Fort Morgan, are intended to help guide the general public in taking individual safety precautions and provide emergency management personnel with a tool to efficiently manage emergency flood operations and post flood recovery efforts.

Potential responses of the Lower Missouri River Shovelnose Sturgeon (Scaphirhynchus platorynchus) population to a commercial fishing ban

Released October 12, 2018 14:20 EST

2018, Journal of Applied Ichthyology

Nicholas S. Green, Mark L. Wildhaber, Janice L. Albers

We developed an age‐structured population matrix model to perform population viability analysis for Lower Missouri River (LMR) shovelnose sturgeon (Scaphirhynchus platorynchus). We investigated potential effects of the commercial fishing moratorium put in place to help protect the similar‐appearing pallid sturgeon (S. albus). The model applies different components of total variance in life history parameters at different levels: sampling variance (parameter uncertainty) between model iterations; temporal variance (temporal environmental fluctuations) between time steps within iterations; and individual variance (individual differences) within each time‐step. The model predicted annual rates of population increase of 1.96% under historic fishing and 2.67% with removal of historic fishing. We identified combinations of fishing and harvest size restrictions that would permit a sustainable harvest of shovelnose sturgeon. Overall, the ban on commercial fishing of shovelnose sturgeon in the LMR due to similarity of appearance to pallid sturgeon should help the LMR shovelnose sturgeon population begin to rebound while decreasing any negative effects it may have had on pallid sturgeon populations.

Water-quality trends in U.S. rivers, 2002 to 2012: Relations to levels of concern

Released October 12, 2018 14:16 EST

2019, Science of the Total Environment (650) 2314-2324

Megan E. Shoda, Lori A. Sprague, Jennifer C. Murphy, Melissa L. Riskin

Effective management and protection of water resources relies upon understanding how water-quality conditions are changing over time. Water-quality trends for ammonia, chloride, nitrate, sulfate, total dissolved solids (TDS), total nitrogen (TN) and total phosphorus (TP) were assessed at 762 sites located in the conterminous United States between 2002 and 2012. Annual mean concentrations at the start and end of the trend period were compared to an environmentally meaningful level of concern (LOC) to categorize patterns in water-quality changes. Trend direction, magnitude, and the proximity of concentrations to LOCs were investigated. Of the 1956 site-constituent combinations investigated, 30% were above the LOC in 2002, and only six (0.3%) crossed the LOC threshold, either from above or below, indicating that waterquality conditions are not substantially improving, nor are they degrading, in relation to the LOCs. The concentrations of ammonia, nitrate, sulfate, chloride, and TDS tended to be below the LOC, and in cases where the trend was increasing (concentrations approached the LOC from below), the increases were varied and small in magnitude. In contrast, concentrations of TN and TP tended to be above the LOC, and where the trend was decreasing (concentrations approached the LOC from above), the decreases were larger in magnitude and more consistent. These results indicate that if water-quality conditions continue to trend in the same direction, at the same rate, for all sites and constituents studied, elevated concentrations are more likely to drop below an LOC before low concentrations will exceed an LOC.

Trends in nonindigenous aquatic species richness in the United States reveal shifting spatial and temporal patterns of species introductions

Released October 12, 2018 14:14 EST

2018, Aquatic Invasions (13) 323-338

Michael J. Mangiante, Amy J. S. Davis, Stephanie Panlasigui, Matthew E. Neilson, Ian Pfingsten, Pam L. Fuller, John A. Darling

Understanding the spatial and temporal dynamics underlying the introduction and spread of nonindigenous aquatic species (NAS) can provide important insights into the historical drivers of biological invasions and aid in forecasting future patterns of nonindigenous species arrival and spread. Increasingly, public databases of species observation records are being used to quantify changes in NAS distributions across space and time, and are becoming an important resource for researchers, managers, and policy-makers. Here we use publicly available data to describe trends in NAS introduction and spread across the conterminous United States over more than two centuries of observation records. Available data on first records of NAS reveal significant shifts in dominance of particular introduction patterns over time, both in terms of recipient regions and likely sources. These spatiotemporal trends at the continental scale may be subject to biases associated with regional variation in sampling effort, reporting, and data curation. We therefore also examined two additional metrics, the number of individual records and the spatial coverage of those records, which are likely to be more closely associated with sampling effort. Our results suggest that broad-scale patterns may mask considerable variation across regions, time periods, and even entities contributing to NAS sampling. In some cases, observed temporal shifts in species discovery may be influenced by dramatic fluctuations in the number and spatial extent of individual observations, reflecting the possibility that shifts in sampling effort may obscure underlying rates of NAS introduction.

Estimating the pressure-limited CO2 injection and storage capacity of the United States saline formations: Effect of the presence of hydrocarbon reservoirs

Released October 12, 2018 14:00 EST

2018, International Journal of Greenhouse Gas Control (79) 14-24

Hossein Jahediesfanjani, Peter D. Warwick, Steven T. Anderson

The U.S. Geological Survey (USGS) national assessment of carbon dioxide (CO2) storage capacity evaluated 192 saline Storage Assessment Units (SAUs) in 33 U.S. onshore sedimentary basins that may be utilized for CO2 storage (see USGS Circular 1386). Similar to many other available models, volumetric analysis was utilized to estimate the initial CO2injection and storage capacity of these SAUs based on aquifer characteristics and buoyant and residual trapping. The factor being almost always overlooked in most CO2 storage capacity models is that many of the evaluated SAUs contain large numbers of both conventional and unconventional discovered and undiscovered oil and gas reservoirs. The hydrocarbon production and pressure distribution of the resident oil and gas reservoirs may be negatively influenced by the propagated CO2 plume and pressure front resulting from a CO2 injection and storage operation in the surrounding SAU.

To have a more realistic and accurate estimation of CO2 injection and storage capacity in saline formations, a model was previously developed that considers the CO2 injectivity of a given formation, underground pressure build-up limitations imposed by the rock fracturing pressure and the presence of hydrocarbon reservoirs within these aquifers. The developed method estimates the pre–brine extraction, pressure-limited CO2 injection and storage capacity of a saline formation by applying 3D numerical simulation only on the effective injection area (Aeff) surrounding each CO2 injection well utilizing TOUGH2-ECO2N simulation software.

Variability of organic carbon content and the retention and release of trichloroethene in the rock matrix of a mudstone aquifer

Released October 12, 2018 13:56 EST

2018, Journal of Contaminant Hydrology (217) 32-42

Allen M. Shapiro, Rebecca J. Brenneis

Contaminants diffusing from fractures into the immobile porosity of the rock matrix are subject to prolonged residence times. Organic contaminants can adsorb onto organic carbonaceous materials in the matrix extending contaminant retention. An investigation of spatial variability of the fraction of organic carbon (foc) is conducted on samples of rock core from seven closely spaced boreholes in a mudstone aquifer contaminated with trichloroethene (TCE). A total of 378 samples were analyzed at depths between 14 and 36 m below land surface. Mudstone units associated with deep water deposition have the largest foc, with a maximum value of 0.0396, and units associated with shallow water deposition have the smallest foc. Even though foc correlates with depositional conditions, foc still varies over more than an order of magnitude in continuous mudstone layers between boreholes, and there is large variability in foc over short distances perpendicular to bedding. Simulations of diffusion and linear equilibrium adsorption of TCE using spatially variable foc in the rock matrix show order of magnitude variability in the adsorbed TCE over short distances in the matrix and residence times extending to hundreds of years following remediation in adjacent fractures. Simulations using average values of foc do not capture the range of TCE mass that can be retained in a rock matrix characterized by spatially variable foc. Bounds on TCE mass within the rock matrix can be obtained by simulations with spatially uniform values of focequal to the maximum and minimum values of foc for a given mudstone unit.

Geology and assessment of undiscovered oil and gas resources of the Lena-Anabar Basin Province, 2008

Released October 12, 2018 13:29 EST

2018, Professional Paper 1824-T

Timothy R. Klett, Janet K. Pitman

Thomas E. Moore, Donald L. Gautier, editor(s)

The U.S. Geological Survey (USGS) assessed the potential for undiscovered oil and gas resources of the Lena-Anabar Basin Province as part of its Circum-Arctic Resource Appraisal program. The province is in the Russian High Arctic and is located between the Laptev Sea and the Siberian craton. Three assessment units (AUs) were defined for this study—the Lena-Anabar Basin AU, the Lena-Anabar Basin Updip AU, and the Sukhan-Motorchun Riphean Rift AU—and were assessed for undiscovered, technically recoverable resources. The estimated mean volumes of undiscovered oil and gas resources for the Lena-Anabar Basin Province are ~2 billion barrels of crude oil, ~2 trillion cubic feet of natural gas, and <1 billion barrels of natural gas liquids. All of the undiscovered petroleum resources are north of the Arctic Circle.

Geology and assessment of undiscovered oil and gas resources of the Mezen’ Basin Province, 2008

Released October 12, 2018 13:28 EST

2018, Professional Paper 1824-M

Timothy R. Klett, Janet K. Pitman

Thomas E. Moore, Donald L. Gautier, editor(s)

The Mezen’ Basin Province is situated along the White and Barents Seas in the northeastern part of the Russian Federation. Only a small area of the province, part of one graben, extends slightly north of the Arctic Circle onto the Kanin-Kola monocline, where it converges with the Timan-Varanger deformed belt and the Fennoscandian shield.

The main petroleum potential in the Mezen’ Basin Province is associated with grabens in which clastic Proterozoic source and reservoir rocks are present. One Proterozoic-Paleozoic Composite Total Petroleum System was defined, although Paleozoic and younger strata are too thin (<1–2 km) for significant petroleum accumulation. The total thickness of the sedimentary interval is <6 km. The Northwest Mezen’ Basin Assessment Unit was delineated north of the Arctic Circle. Proterozoic (Riphean) mudstone is organic rich and thermally mature, providing a source for petroleum; younger Proterozoic (Vendian) rocks are also organic rich but thermally immature (Kuz’min, 2005). Because of its limited extent, the potential for an oil or gas field exceeding the minimum size of 50 million barrels of oil equivalent (MMBOE) within the small graben north of the Arctic Circle is remote (assessment-unit probability, 0.005). Therefore, the Mezen’ Basin Province was not quantitatively assessed.

Geologic map of the Osage SW 7.5ʹ quadrangle, Newton, Madison, and Carroll Counties, Arkansas

Released October 11, 2018 16:30 EST

2018, Scientific Investigations Map 3416

Kenzie J. Turner, Mark R. Hudson

This map summarizes the geology of the U.S. Geological Survey Osage SW 7.5-minute quadrangle in the Ozark Plateaus region of northern Arkansas. Physiographically, the Osage SW quadrangle is located within a transitional area between the Boston Mountains to the south, and the Springfield Plateau to the north. Geologically, the area is on the southern flank of the Ozark dome; an uplift with the oldest rocks exposed at its center in the St. Francois Mountains in Missouri. Exposed within the quadrangle is an approximately 1,460-foot-thick sequence of Ordovician, Mississippian, and Pennsylvanian carbonate and clastic sedimentary rocks that have been mildly deformed by a series of faults and folds. The southeasternmost corner of the map area falls within the Buffalo National River—a park which encompasses the Buffalo River and adjacent land that is administered by the National Park Service.

Some practical approaches to world petroleum resource assessment

Released October 11, 2018 14:38 EST

1986, Book chapter

D.H. Root, Emil Attanasi, Charles D. Masters

Uncertainty in petroleum resource estimation can be mitigated by using different approaches in making resource estimates for a given area. We divide methods and data into two broad categories. The first is based on geologic data, which aim at estimating the resources of a basin by gaining an understanding of the processes of petroleum formation, migration, and trapping. The second is based on statistical methods, which estimate the resources of a basin by extrapolating the industry's past experience in drilling and discovery to forecast future discoveries. Results of these approaches are compared for Nigeria, North Africa, and many of the world's offshore areas. Undiscovered offshore petroleum resources outside the United States, Canada, and communist countries were estim ted by both methods to be ~ 130 billion bbl. For Nigeria the two methods agree at about 4-6 billion bbl of undiscovered oil. In contrast, for North Africa, where the geologic estimate of undiscovered petroleum is 16 billion bbl and the statistical estimate is 5 billion bbl, the two methods are not in close agreement.

Dissolved pesticide concentrations in the lower Sacramento River and its source waters, California, 2016

Released October 11, 2018 14:32 EST

2018, Open-File Report 2018-1153

Sean M. Stout, James L. Orlando, Megan McWayne-Holmes, Corey Sanders, Michelle Hladik

As part of a collaborative study designed to better understand water-quality conditions in the Sacramento River, surface-water samples were collected from the lower Sacramento River and five of its tributaries and then analyzed by the U.S. Geological Survey for a suite of 162 current-use pesticides and pesticide degradates. Samples were collected in May and October 2016 at 16 sites on the Sacramento River and its tributaries. Samples were analyzed for pesticide concentrations by using gas chromatography with mass spectrometry and liquid chromatography with tandem mass spectrometry laboratory methods.

A total of 27 pesticides and pesticide degradates were detected in the water samples collected during the study (12 herbicides, 9 insecticides, 5 fungicides, and 1 synergist). Two herbicides were detected in the suspended sediments filtered from the water samples. Pesticides were detected in 100 percent of the water samples, and mixtures of two or more pesticides were detected at all sites and in all but four samples. The pesticides detected most frequently in the May and October sampling periods were the herbicides hexazinone (detected in 88 percent of the water samples), and diuron (84 percent), and the fungicide azoxystrobin (84 percent). Pesticide concentrations ranged from below the method detection limits to 576 nanograms per liter (clomazone). All pesticides were detected at concentration levels lower than the U.S. Environmental Protection Agency’s aquatic life benchmarks (U.S. Environmental Protection Agency, 2017).

During the May sampling period, the fungicides boscalid and azoxystrobin (both 94 percent); the herbicides clomazone, diuron, and hexazinone (all 94 percent); thiobencarb (88 percent); and metolachlor (81 percent) were the most frequently detected compounds. During the October sampling period, the herbicides hexazinone (81 percent) and diuron (75 percent) and the herbicide degradates 3,4-dichloroaniline (75 percent) and N-3,4-dichlorophenyl-N-methyl-urea (50 percent), along with the fungicide azoxystrobin (75 percent) and the insecticide methoxyfenozide (63 percent), were the most frequently detected compounds.

Aeromagnetic map of Mountain Pass and vicinity, California and Nevada

Released October 11, 2018 13:56 EST

2018, Scientific Investigations Map 3412-B

David A. Ponce, Kevin M. Denton

David A. Ponce, editor(s)

Magnetic investigations of Mountain Pass and vicinity were begun as part of an effort to study regional crustal structures as an aid to understanding the geologic framework and mineral resources of the eastern Mojave Desert. The study area, which straddles the state boundary between southeastern California and southern Nevada, encompasses Mountain Pass, which is host to one of the world’s largest rare earth element carbonatite deposits.

The deposit is found along a north-northwest-trending, fault-bounded block that extends along the eastern parts of the Clark Mountain Range, Mescal Range, and Ivanpah Mountains. This Paleoproterozoic block is composed of a 1.7-Ga metamorphic complex of gneiss and schist that underwent widespread metamorphism and associated plutonism during the Ivanpah orogeny. The Paleoproterozoic rocks were intruded by a Mesoproterozoic (1.4 Ga) ultrapotassic alkaline intrusive suite and carbonatite body. The intrusive rocks include, from oldest to youngest, shonkinite, mesosyenite, syenite, quartz syenite, potassic granite, carbonatite, carbonatite dikes, and late shonkinite dikes.

Generally speaking, magnetic anomalies reflect lateral changes in subsurface magnetization that can be used to infer subsurface geologic structure, revealing variations in lithology and delineating geologic features such as faults, plutons, volcanic rocks, calderas, and sedimentary basins.

A regional aeromagnetic map was derived from statewide aeromagnetic maps of California and Nevada that were compiled from numerous surveys flown at various flightline altitudes and spacings. This compilation, although composed of surveys acquired using different specifications, allows seamless interpretation of magnetic anomalies across survey boundaries.

In addition, a high-resolution aeromagnetic survey was flown by helicopter over parts of the Clark Mountain Range, Mescal Range, and Ivanpah Mountains. The resulting mapped magnetic anomalies show in much greater detail the complex subsurface structures in the Mountain Pass area.

Isostatic gravity map of Mountain Pass and vicinity, California and Nevada

Released October 11, 2018 13:52 EST

2018, Scientific Investigations Map 3412-A

David A. Ponce, Kevin M. Denton

David A. Ponce, editor(s)

Gravity investigations of Mountain Pass and vicinity were begun as part of an effort to study regional crustal structures as an aid to understanding the geologic framework and mineral resources of the eastern Mojave Desert. The study area, which straddles the state boundary between southeastern California and southern Nevada, encompasses Mountain Pass, which is host to one of the world’s largest rare earth element carbonatite deposits.

The deposit is found along a north-northwest-trending, fault-bounded block that extends along the eastern parts of the Clark Mountain Range, Mescal Range, and Ivanpah Mountains. This Paleoproterozoic block is composed of a 1.7-Ga metamorphic complex of gneiss and schist that underwent widespread metamorphism and associated plutonism during the Ivanpah orogeny. The Paleoproterozoic rocks were intruded by a Mesoproterozoic (1.4 Ga) ultrapotassic alkaline intrusive suite and carbonatite body. The intrusive rocks include, from oldest to youngest, shonkinite, mesosyenite, syenite, quartz syenite, potassic granite, carbonatite, carbonatite dikes, and late shonkinite dikes.

Generally speaking, gravity anomalies can be used to infer subsurface geologic structure, revealing variations in lithology and delineating features such as faults, plutons, volcanic centers, calderas, and deep sedimentary basins.

As part of this study, gravity data from more than 2,400 stations were collected and processed to identify lateral changes in subsurface density. Gravity stations were distributed across parts of Shadow Valley, Clark Mountain Range, Mescal Range, Ivanpah Mountains, and Ivanpah Valley. The new gravity data were combined with preexisting gravity data from the surrounding areas in California and Nevada. All gravity data were gridded using a minimum curvature algorithm at an interval of 200 m, and the result is displayed as a color-contour isostatic gravity map.

Geophysical and geologic maps of Mountain Pass and vicinity, California and Nevada

Released October 11, 2018 13:51 EST

2018, Scientific Investigations Map 3412

David A. Ponce, editor(s)

U.S. Geological Survey Scientific Investigations Map 3412 is a series of products that consists of geophysical and geologic maps of Mountain Pass and vicinity, California. Maps A and B (red outline in above map image) are gravity and aeromagnetic maps, respectively. The map series was begun as part of an effort to study regional crustal structures as an aid to understanding the geologic framework and mineral resources of the southeast Mojave Desert.

Mountain Pass resides within the southeast Mojave Desert, and it is host to a one of the world’s largest rare earth element carbonatite deposits. The deposit is found along a north-northwest- trending, fault-bounded block that extends along the eastern parts of the Clark Mountain Range, Mescal Range, and Ivanpah Mountains. This Paleoproterozoic block is composed of a 1.7-Ga metamorphic complex of gneiss and schist that underwent widespread metamorphism and associated plutonism during the Ivanpah orogeny. The Paleoproterozoic rocks were intruded by a Mesoproterozoic (1.4 Ga) ultrapotassic alkaline intrusive suite and carbonatite body. The intrusive rocks include, from oldest to youngest, shonkinite, mesosyenite, syenite, quartz syenite, potassic granite, carbonatite, carbonatite dikes, and late shonkinite dikes.

Each map in the series provides the basis for geophysical and geologic interpretations of the Mountain Pass carbonatite terrane. Combined, they provide a comprehensive framework of the regional subsurface geologic structure of the area. Together, they form the first publicly available series of geophysical and geologic maps of this part of the southeast Mojave Desert.

Material balance approach for determining oil saturation at the start of carbon dioxide enhanced oil recovery

Released October 11, 2018 12:00 EST

2018, Open-File Report 2018-1146

Mahendra K. Verma

Oil producers have been using enhanced oil recovery methods, including (1) thermal recovery for heavy oil and (2) carbon dioxide enhanced oil recovery (CO2-EOR) for medium or light oil, to maximize oil recovery from existing reservoirs. The CO2-EOR method is widely used for recovering additional oil after waterflood, which leaves behind a large volume of oil in the reservoir. Completing a CO2-EOR feasibility study requires values of various geologic, petrophysical, and reservoir properties, as well as production data. Most of the required data are available except for two critical parameters: (1) the oil saturation at the start of CO2-EOR and (2) the oil recovery factor. Several methods, including core analysis, open-hole and cased-hole well logging, well-to-well tracer tests, and material balance, have been deployed to determine the residual oil saturation after waterflood (at which the relative permeability to oil nears zero) or remaining oil saturation after waterflood, equal to the oil saturation at the start of CO2-EOR. This report presents the material balance approach, which is less expensive than other approaches and provides reasonably accurate values of oil saturation at the start of CO2-EOR, and therefore is more useful when assessing a large number of reservoirs.

Modeling resource selection of bobcats (Lynx rufus) and vertebrate species distributions in Orange County, southern California

Released October 11, 2018 11:44 EST

2018, Open-File Report 2018-1095

Erin E. Boydston, Jeff A. Tracey

For nature reserves in urban settings, wildlife and wildlife habitats may be affected by recreational activities and intensive, adjacent development. Sustaining biodiversity in such reserves is a challenge for land and natural resource managers, but identification of core areas and key resources for wildlife species may help in planning for current and emerging threats. To help identify core areas and resources, we conducted spatial analyses and predictive modeling of vertebrate distributions for a network of nature reserves in densely populated Orange County, California. We primarily focused on bobcats (Lynx rufus), a species with a strong association with natural habitat. Bobcat space use has been correlated with broad, simple land-use categories, but relatively little is known about the influence of greater landscape complexity on habitat suitability for bobcats. To examine habitat selection by bobcats, we developed spatial data layers representing environmental factors that might influence this species, and we used previously collected Global Positioning System tracking data for 30 male and 21 female bobcats to indicate bobcat response to complex landscape factors. We examined these inputs using Resource Selection Function (RSF) modeling and developed spatially explicit models of the probability of bobcat use (selection or avoidance) of landscape characteristics. RSF models highlighted the general importance of reserve habitat for bobcats, but suggested that female bobcats were more dependent that male bobcats on habitat within designated reserves. Male bobcats, which range more widely than female bobcats, were associated with undeveloped areas both within and outside reserves. Small areas were present outside reserves that seemed to provide additional suitable habitat or movement areas for bobcats, potentially through restoration, connectivity, or reduced edge effects.

Although bobcat RSFs suggested areas of high value to this species and potentially other species, taxa can differ greatly in their resource-selection and spatial requirements. Thus, for several species of reptiles, amphibians, and birds, we adapted species distribution models based on occurrence data to examine the response of other vertebrates to the landscape. To identify potential High-Value Areas (HVAs) for single or multiple species, we then developed a step-wise filtering process that can be applied to a series of spatial data layers. We provide examples of alternative decision models for HVAs that capture different elements of biodiversity and a range of management considerations. As landscape and management challenges change, these spatial layers and decision rules can be adjusted based on new information. Our approach thus establishes a general framework for identifying high-value habitat that can be used for current management decisions and refined in the future, depending on management interests and goals and the availability of suitable quality data or adequate surrogate information.

Trends and traditions: Overview and synthesis

Released October 11, 2018 11:38 EST

2018, Book chapter, Trends and traditions: Avifaunal change in western North America, Studies of Western Birds No. 3

W David Shuford, Robert E. Gill Jr., Colleen M. Handel

This paper provides an overview by the editors of a collection of 25 papers for the Studies of Western Birds, to be published in a single volume by Western Field Ornithologists. The title of the volume is: "Trends and traditions: Avifaunal change in western North America."

Spatial decision‐support tools to guide restoration and seed‐sourcing in the Desert Southwest

Released October 11, 2018 11:29 EST

2018, Ecosphere (9) 1-19

Daniel F. Shryock, Lesley A. DeFalco, Todd C. Esque

Altered disturbance regimes and shifting climates have increased the need for large‐scale restoration treatments across the western United States. Seed‐sourcing remains a considerable challenge for revegetation efforts, particularly on public lands where policy favors the use of native, locally sourced plant material to avoid maladaptation. An important area of emphasis for public agencies has been the development of spatial tools to guide selection of genetically appropriate seed. When genetic information is not available, current seed transfer guidelines stipulate use of climate‐based or provisional seed transfer zones, which serve as a proxy for local adaptation by representing climate gradients to which plants are commonly adapted. Despite this guidance, little emphasis has been placed on identifying best practices for deriving provisional seed zones or on incorporating predictions from future climate. We describe a flexible, multivariate procedure for deriving such zones that incorporates a broad range of climatic characteristics while accounting for covariation among climate variables. With this approach, we derive provisional seed zones for four regions in the Desert Southwest (the Mojave Desert, Sonoran Desert, Colorado Plateau, and Southern Great Basin). To facilitate future‐resilient restoration designs, we project each zone into its relative position in the future climate based on near‐term, RCP4.5 and RCP8.5 emissions scenarios. Although provisional seed zones are useful in a variety of contexts, there are also situations in which site‐specific guidance is preferable. To meet this need, we implement Climate Distance Mapper, an interactive decision‐support tool designed to help practitioners match seed sources with restoration sites through an accessible online interface. The application allows users to rank the suitability of seed sources anywhere on the landscape based on multivariate climate distances. Users can perform calculations for either the current or future climates. Additionally, tools are available to guide sample effort in regional‐scale seed collections or to partition the landscape into climate clusters representing suitable planting sites for different seed sources. Our tools and analytic procedures represent a flexible and reproducible framework for advancing native plant development programs in the Desert Southwest and beyond.

A decade of remotely sensed observations highlight complex processes linked to coastal permafrost bluff erosion in the Arctic

Released October 11, 2018 11:23 EST

2018, Environmental Research Letters

Benjamin M. Jones, Louise M. Farquharson, Carson Baughman, Richard M. Buzard, Christopher D. Arp, Guido Grosse, Diana L. Bull, Frank Günther, Ingmar Nitze, Frank Urban, Jeremy L. Kasper, Jennifer M. Frederick, Matthew A. Thomas, Craig Jones, Alejandro Mota, Scott Dallimore, Craig E. Tweedie, Christopher Maio, Daniel H. Mann, Bruce M. Richmond, Ann E. Gibbs, Ming Xiao, Torsten Sachs, Go Iwahana, Mikhail Z. Kanevskiy, Vladimir E. Romanovsky

Eroding permafrost coasts are indicators and integrators of changes in the Arctic System as they are susceptible to the combined effects of declining sea ice extent, increases in open water duration, more frequent and impactful storms, sea-level rise, and warming permafrost. However, few observation sites in the Arctic have yet to link decadal-scale erosion rates with changing environmental conditions due to temporal data gaps. This study increases the temporal fidelity of coastal permafrost bluff observations using near-annual high spatial resolution (&lt;1 m) satellite imagery acquired between 2008 and 2017 for a 9-km segment of coastline at Drew Point, Beaufort Sea coast, Alaska. Our results show that mean annual erosion for the 2007 to 2016 decade was 17.2 m yr&lt;sup&gt;-1&lt;/sup&gt;, which is 2.5 times faster than historic rates, indicating that bluff erosion at this site is likely responding to changes in the Arctic System. In spite of a sustained increase in decadal-scale mean annual erosion rates, mean open water season erosion varied from 6.7 m yr&lt;sup&gt;-1&lt;/sup&gt; in 2010 to more than 22.0 m yr&lt;sup&gt;-1&lt;/sup&gt; in 2007, 2012, and 2016. This variability provided a range of coastal responses through which we explored the different roles of potential environmental drivers. The lack of significant correlations between mean open water season erosion and the environmental variables compiled in this study indicates that we may not be adequately capturing the environmental forcing factors, that the system is conditioned by long-term transient effects or extreme weather events rather than annual variability, or that other not yet considered factors may be responsible for the increased erosion occurring at Drew Point. Our results highlight an increase in erosion at Drew Point in the 21st century as well as the complexities associated with unraveling the factors responsible for changing coastal permafrost bluffs in the Arctic.

California Gull population growth and ecological impacts in the San Francisco Bay estuary, 1980–2016

Released October 11, 2018 11:06 EST

2018, Book chapter, Trends and traditions: Avifaunal change in western North America, Studies of Western Birds No. 3

Catherine E. Burns, Joshua T. Ackerman, Natalie B. Washburn, Jill Bluso-Demers, Caitlin Robinson-Nilsen, Cheryl Strong

The breeding population of California Gulls (Larus californicus) in the San Francisco Bay estuary increased from 24 individuals in 1980 to a peak of over 53,000 in 2014, then declined to 38,040 in 2016. The expansion of the breeding population may be related to the availability of suitable nesting sites in close proximity to anthropogenic food subsidies at landfills. Telemetry data indicate that California Gull movements are largely dictated by the two primary landfills in South San Francisco Bay. The large population of California Gulls has had negative effects on locally breeding shorebirds and terns, especially the Forster’s Tern (Sterna forsteri), American Avocet (Recurvirostra americana), and Western Snowy Plover (Charadrius nivosus nivosus). In South San Francisco Bay, California Gulls were responsible for 13% and 38% of egg predation events at nests of American Avocets and Snowy Plovers, respectively, and 55% and 54% of chick predation events of American Avocets and Forster’s Terns, respectively. The forced relocation of the largest gull colony (~24,000) at Pond A6 in 2010 resulted in increased survival of Forster’s Tern chicks at the adjacent colony at Pond A7 in 2011. The California Gull population and its effects on locally breeding shorebirds and terns are among the most pressing concerns for wetland managers within the San Francisco Bay estuary, especially for the South Bay Salt Pond Restoration Project. Further research is needed to evaluate the gull’s reproductive rates, habitat use, and annual movements and so to clarify its demographics and to quantify its effects on other breeding birds.

Critical minerals: A review of elemental trends in comprehensive criticality studies

Released October 11, 2018 10:57 EST

2018, Resources Policy

Sarah M. Hayes, Erin A. McCullough

Mineral criticality is a subjective concept that has evolved throughout history. An abundance of literature on this topic has been published over the last decade, encompassing a variety of criteria and methodologies. To our knowledge, this work is the first large-scale effort to organize and analyze recent comprehensive criticality studies in order to determine if a consensus exists within the global community as to which elements are critical. Here, we set aside methodological differences and analyze the results of 32 comprehensive nonfuel mineral criticality studies that evaluate at least 10 elements. Of the 56 elements or elemental groups evaluated, the three most commonly identified as critical in these studies are the rare-earth elements (REE), the platinum-group metals (PGM), and indium. Most of the studies also identify tungsten, germanium, cobalt, niobium, tantalum, gallium, and antimonyas critical. These results are consistent with the 11 most recent studies, published post-2014, which also identify bismuth as critical. Furthermore, the same elements identified in the complete dataset, except antimony, were designated as critical when normalized by geographic region. Magnesium was also deemed critical. Elements may be identified consistently as critical for several reasons; similarities in methodologies, which embody evolving perceptions of risk, or changing national and institutional priorities. This work compiles a large number of recent criticality studies in an effort to define a consensus of currently critical materials, essentially defining the modern criticality paradigm, which is valuable when interpreting an individual perspective in more global context.

Completion summary for borehole TAN-2312 at Test Area North, Idaho National Laboratory, Idaho

Released October 11, 2018 10:47 EST

2018, Scientific Investigations Report 2018-5118

Brian V. Twining, Roy C. Bartholomay, Mary K. V. Hodges

In 2017, the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, drilled and constructed borehole TAN-2312 for stratigraphic framework analyses and long-term groundwater monitoring of the eastern Snake River Plain aquifer at the Idaho National Laboratory in southeast Idaho. The location of borehole TAN-2312 was selected because it was downgradient from TAN and believed to be the outer extent of waste plumes originating from the TAN facility. Borehole TAN-2312 initially was cored to collect continuous geologic data, and then re-drilled to complete construction as a monitor well. The final construction for borehole TAN-2312 required 16- and 10-inch (in.) diameter carbon-steel well casing to 37 and 228 feet below land surface (ft BLS), respectively, and 9.9-in. diameter open-hole completion below the casing to 522 ft BLS. Depth to water is measured near 244 ft BLS. Following construction and data collection, a temporary submersible pump and water-level access line were placed near 340 ft BLS to allow for aquifer testing, for collecting periodic water samples, and for measuring water levels.

Borehole TAN-2312 was cored continuously, starting at the first basalt contact (about 37 ft BLS) to a depth of 568 ft BLS. Not including surface sediment (0–37 ft), recovery of basalt and sediment core at borehole TAN-2312 was about 93 percent; however, core recovery from 170 to 568 ft BLS was 100 percent. Based on visual inspection of core and geophysical data, basalt examined from 37 to 568 ft BLS consists of about 32 basalt flows that range from approximately 3 to 87 ft in thickness and 4 sediment layers with a combined thickness of approximately 76 ft. About 2 ft of total sediment was described for the saturated zone, observed from 244 to 568 ft BLS, near 296 and 481 ft BLS. Sediment described for the saturated zone were composed of fine-grained sand and silt with a lesser amount of clay. Basalt texture for borehole TAN-2312 generally was described as aphanitic, phaneritic, and porphyritic. Basalt flows varied from highly fractured to dense with high to low vesiculation.

Geophysical and borehole video logs were collected after core drilling and after final construction at borehole TAN-2312. Geophysical logs were examined synergistically with available core material to suggest zones where groundwater flow was anticipated. Natural gamma log measurements were used to assess sediment layer thickness and location. Neutron and gamma-gamma source logs were used to identify fractured areas for aquifer testing. Acoustic televiewer logs, fluid logs, and electromagnetic flow meter results were used to identify fractures and assess groundwater movement when compared against neutron measurements. Furthermore, gyroscopic deviation measurements were used to measure horizontal and vertical displacement for borehole TAN-2312.

After construction of borehole TAN-2312, a single-well aquifer test was completed September 27, 2017, to provide estimates of transmissivity and hydraulic conductivity. Estimates for transmissivity and hydraulic conductivity were 1.51×102 feet squared per day and 0.23 feet per day, respectively. During the 220-minute aquifer test, well TAN-2312 had about 23 ft of measured drawdown at sustained pumping rate of 27.2 gallons per minute. The transmissivity and hydraulic conductivity estimates for well TAN-2312 were lower than the values determined from previous aquifer tests in other wells near Test Area North.

Water samples were analyzed for cations, anions, metals, nutrients, volatile organic compounds, stable isotopes, and radionuclides. Water samples for most of the inorganic constituents showed concentrations near background levels for eastern regional groundwater. Water samples for stable isotopes of oxygen, hydrogen, and sulfur indicated some possible influence of irrigation on the water quality. The volatile organic compound data indicated that this well had some minor influence by wastewater disposal practices at Test Area North.

Nearshore single-beam bathymetry data collected in 2015, Dauphin Island, Alabama

Released October 11, 2018 10:30 EST

2018, Data Series 1095

Nancy T. DeWitt, Chelsea A. Stalk, James G. Flocks, Julie C. Bernier, Kyle W. Kelso, Jake J. Fredericks, Thomas M. Tuten

Dauphin Island, Alabama, is a barrier island located in the northern Gulf of Mexico that supports local residences, tourism, commercial infrastructure, and historic Fort Gaines. During the past decade, Dauphin Island was affected by several major hurricanes—Hurricanes Ivan (2004), Katrina (2005), and Isaac (2012)—and storms, along with sea-level rise, continue to present a threat to island stability. State and Federal managers are using a scientific approach to identify, formulate, and implement a long-term plan to provide restoration options for Dauphin Island, thereby helping increase its resilience against future storms and sea-level rise. Island morphology, including current bathymetry and shoreline data, is one scientific domain being investigated in an effort to produce a comprehensive restoration plan funded by an interagency grant from the National Fish and Wildlife Foundation Gulf Environmental Benefit Fund.

In August 2015, the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center (SPCMSC), in cooperation with the U.S. Army Corps of Engineers at the U.S. Army Engineer Research and Development Center, Mobile District, and the State of Alabama, conducted bathymetric surveys of the nearshore waters surrounding Dauphin Island. This report provides a detailed methodology for the data acquisition and post-processing of 1,165-line kilometers (km) of single-beam bathymetry data collected under the USGS–SPCMSC Alabama Barrier Island Restoration Study. These data were acquired and processed under USGS field activity number 2015–326–FA. Data are provided in three datums: (1) the International Terrestrial Reference Frame of 2000, ellipsoid height (from –47.04 meters (m) to –29.36 m); (2) the North American Datum of 1983, CORS96 realization (NAD83 (CORS96)) horizontal, and the North American Vertical Datum 1988 GEOID12A vertical (from –0.24 m to –17.33 m); and (3) NAD83 (CORS96) horizontal, and mean lower low water vertical (from –0.12 m to –17.93 m). The x,y,z point datasets, trackline shapefiles, digital and handwritten Field Activity Collection Systems logs, one 50-m digital elevation model, and formal Federal Geographic Data Committee metadata are obtainable from the Data Downloads page or the associated USGS data release.

Topics in coal geochemistry—Short course

Released October 10, 2018 13:05 EST

2018, Open-File Report 2018-1145

Allan Kolker

This short course was prepared at the request of Servicio Geológico Colombiano (SGC) as a module for staff training. Prior to the short course, the SGC expressed interest in receiving training in (1) geochemistry and quality of coal; (2) geochemistry of trace elements in coal; (3) mercury and halogens in coal; (4) characterization and cycling of atmospheric mercury; (5) mercury, trace elements, and organic constituents in atmospheric fine particulate matter; (6) mercury in coal and the effect of coal quality on mercury emissions from combustion systems; (7) environmental and health effects related to coal use; and (8) related topics in coal combustion processes. A five-session short course was prepared that addressed all but the engineering aspects of coal use. In the sections that follow, topic overviews are given for the material that was presented. Brief descriptions of each slide are given in appendix 1, and the actual short course material, presented as a series of PowerPoint slides, is included in Portable Document Format (PDF) as appendix 2.

Field observations of alongshore runup variability under dissipative conditions in presence of a shoreline sandwave

Released October 10, 2018 10:34 EST

2018, Journal of Geophysical Research C: Oceans

Nadia Senechal, Giovanni Coco, Nathaniel G. Plant, Karin R. Bryan, Jennifer Brown, Jamie MacMahan

Video measurements of runup were collected at low tide along several profiles covering an alongshore distance of 500 m. The morphology displayed a complex shape with a shoreline sandwave in the lower beach face of about 250 m long mirrored in the inner sandbar. Wave conditions were stationary and moderate (offshore height of 2 m and peak period of nearly 13 s) but yet dissipative. Runup energy was dominated by infragravity frequencies. Alongshore variations in runup (by a factor up to 3) observed both in the incident and infragravity bands were much higher than reported previously (e.g., Guedes et al., 2012, https://doi.org/10.1016/j.csr.2012.08.022; Ruggiero et al., 2004, https://doi.org/10.1029/2003JC002160) while the alongshore variations in other environmental parameters (e.g., foreshore beach slope) appear to be much lower. Our data suggest that the beach morphology in the inner surf zone plays a crucial role by inducing rapid and significant modification in the incident wave pattern and the alongshore coherence length scales were consistent with the typical alongshore length scale of the morphology.

Geologic framework and hydrostratigraphy of the Edwards and Trinity aquifers within Hays County, Texas

Released October 09, 2018 19:46 EST

2018, Scientific Investigations Map 3418

Allan K. Clark, Diana E. Pedraza, Robert R. Morris

The Edwards and Trinity aquifers are classified as major aquifers by the Texas Water Development Board and are major sources of water in south-central Texas, where Hays County is located. Detailed maps and descriptions of the geologic framework and hydrostratigraphic units (HSUs) of these karstic aquifers in Hays County are needed for water managers to effectively manage groundwater resources in the area. During 2016–18, the U.S. Geological Survey, in cooperation with the Edwards Aquifer Authority, documented the geologic framework and hydrostratigraphy of the Edwards and Trinity aquifers for a large part of Hays County, characterizing approximately 560 square miles of the county. The report includes a 1:24,000-scale hydrostratigraphic map and descriptions of the geology and HSUs in the study area. In addition, parts of the adjacent upper confining unit to the Edwards aquifer are described.

The rocks exposed within the study area are within outcrops of the Trinity and Edwards Groups and the overlying Washita, Eagle Ford, Austin, and Taylor Groups. The rocks are sedimentary and formed during the Cretaceous age. The principal structural feature in Hays County is the Balcones fault zone, which is the result of late Oligocene and early Miocene age high-angle normal faulting and fracturing. Hydrostratigraphically, the exposed rocks represent a section of the upper confining unit to the Edwards aquifer, the Edwards aquifer, the upper zone of the Trinity aquifer, the middle zone of the Trinity aquifer, and the upper part of the lower zone of the Trinity aquifer. Complexity in the aquifer system results from a combination of the original depositional history, bioturbation, primary and secondary porosity, diagenesis, fracturing, and faulting.

Distribution of mining-related trace elements in streambed and flood-plain sediment along the middle Big River and tributaries in the Southeast Missouri Barite District, 2012–15

Released October 09, 2018 14:11 EST

2018, Scientific Investigations Report 2018-5103

David C. Smith, John G. Schumacher

Lead mining first began in the Big River watershed during the 1700s. Lead was the primary metal mined throughout most of the 1700s and early 1800s and it continued to be mined until the mid-1900s. Barite mining began in the middle part of the watershed in the mid- to late 1800s. Although considerable attention has been given to concentrations of miningrelated trace elements (mostly cadmium, lead, and zinc) in the Big River and its tributaries draining the Old Lead Belt, there is less information regarding concentrations of mining-related trace elements in tributaries draining the Barite District in southeast Missouri, which is downstream from the Old Lead Belt, and the contribution of sediment transported from this district to trace elements in lower reaches of the Big River. The purpose of this report is to present results of an investigation of the distribution of mining-related trace elements in sediments in the middle reach of the Big River downstream from the Old Lead Belt and the Big River tributaries that drain a large part of the Barite District.

In general, concentrations of cadmium and lead in streambed sediment were largest in samples from the Big River and smallest in Barite District tributary samples. Concentrations of zinc were somewhat similar in the Big River and Barite District tributaries; however, higher concentrations were present in upstream Big River site samples, as well as in samples from one site on Maddin Creek and at another site on Old Mines Creek that drains the Barite District. Barium concentrations were considerably larger in samples from Barite District tributaries compared to samples collected on the Big River. Samples collected downstream from the Barite District on the Big River had considerably larger barium concentrations than samples collected upstream from the Barite District.

Flood-plain core samples were collected from 26 cores at 5 transect locations along tributaries in the Barite District. Of the individual 693 bulk (unsieved) samples from these cores analyzed by x-ray fluorescence, the probable effects concentration (PEC) values were exceeded for cadmium (PEC of 4.98 milligrams per kilogram [mg/kg], 218 samples), lead (PEC of 128 mg/kg, 91 samples), nickel (PEC of 48.6 mg/kg, 45 samples), and zinc (PEC of 459 mg/kg, 77 samples). Of the 693 samples, 21 exceeded the U.S. Environmental Protection Agency residential yard cleanup level of 400 mg/kg for lead; 19 of these were samples from a single transect near the mouth of Mineral Fork Creek where its flood plain joins the Big River flood plain.

Shortly after the December 2015 flood on the Big River (the third largest flood along the river since the 1950s), 23 samples of fine sediment deposited from the flood were collected from the Big River flood plain upstream and downstream from the Barite District and several tributaries. Overall, the general pattern of barium, lead, and zinc concentrations in the 2015 flood sediment samples was similar to that observed in the streambed-sediment samples.

Overall concentrations of barium were larger at Big River sites downstream from the Barite District, and cadmium, lead, and zinc concentrations were generally similar or smaller at sites downstream from the Barite District when compared to sites upstream from the Barite District. These data indicate a substantial influx of barium from the Barite District into the Big River but only a minimal influx of cadmium, lead, and zinc.

The Central African Republic Diamond Database—A geodatabase of archival diamond occurrences and areas of recent artisanal and small-scale diamond mining

Released October 09, 2018 12:25 EST

2018, Open-File Report 2018-1088

Jessica D. DeWitt, Peter G. Chirico, Sarah E. Bergstresser, Inga E. Clark

The alluvial diamond deposits of the Central African Republic (CAR) are mined almost exclusively by way of informal artisanal and small-scale mining (ASM) methods. ASM sites range in diameter from a few meters to 30 meters or more, and are typically excavated by crews of diggers using hand tools, sieves, and jigs. CAR’s reported annual production has ranged from 300,000 to 470,000 carats over the past decade. This production is significant for CAR because it accounts for a large portion of the country’s export income and employs an estimated 60,000 to 90,000 miners nationally. Diamond production has also been linked to the violent conflict and political instability which have plagued the country for decades. The most recent conflict began in 2012 and resulted in an international embargo on the export of rough diamonds from CAR. This embargo was followed by a ceasefire and a return of peace in certain zones of the country in 2015; however, political and economic instability continues to afflict many areas of the country. International efforts to restore peace in CAR have included United Nations support as well as international technical assistance in tracking, assessing, and monitoring diamond production. In 2015, the Kimberley Process (KP) developed an operational framework allowing for legitimate exports from five subprefectures in CAR that were deemed to be compliant with KP internal controls and which were also considered to be free from systematic violence or control of armed groups.

The goal of this study was to address information gaps regarding the location and extent of diamond occurrences and mining activity through the integration of geologic research with remote sensing, geographic information systems analysis, and fieldwork. Effective and efficient monitoring of diamond mining activity using satellite imagery requires detailed understanding of the geographic distribution of diamond sources and mining activities.

A two-phase methodology was developed to address the knowledge gaps. The first phase consisted of the creation of a comprehensive geospatial catalogue of diamond mining and occurrence locations from archival records such as historical maps, mining reports, academic publications, and field data. Building upon this locational database, the second phase consisted of the creation of a geospatial dataset cataloguing current mining activity locations through manual interpretation of recently acquired satellite imagery. The accuracy of this second geospatial dataset was then assessed using field observations made between 2016 and 2017 by the U.S. Agency for International Development’s Property Rights and Artisanal Diamond Development II project. This report presents a two-part geodatabase: part 1 contains the locations of diamond mine sites and occurrences from archival sources, and part 2 indicates areas of current or recent mining activity. This geodatabase is unique in its temporal and spatial extent and may be used to analyze the geographic distribution of CAR’s known diamond resources, to assess the effect of recent violent conflicts and KP actions on diamond produc-tion, to provide decision makers with information regarding small-scale diamond mining, and to improve the monitoring of mining in regions of the country prone to conflict.

The significance of dinoflagellates in the Miocene Choptank Formation beneath the Midlothian gravels in the southeastern Virginia Piedmont

Released October 09, 2018 10:48 EST

2018, Stratigraphy (15) 179-195

Lucy E. Edwards, Robert E. Weems, Mark W. Carter, David B. Spears, David S. Powars

The Fall Line (formally “Tidewater Fall Line”) separates the more resistant igneous, metamorphic, and consolidated sedimentary rocks of the Piedmont from the typically unconsolidated deposits of the Coastal Plain of Virginia. Widespread but now discontinuous patches of a deeply weathered sand and gravel are found west of the Fall Line, capping the highest hilltops. Near the community of Midlothian, Virginia, the gravels are underlain by fine-grained marine silts that bear an informative assemblage of fossil dinoflagellate cysts (dinocysts). In situ dinocysts belong to middleMiocene zone DN7, which is calibrated to ~12-13 Ma. These deposits are assigned to the upper part of the Choptank Formation, which crops out ~ 25 km(15 mi) to the east at an elevation ~ 60m(200 ft) lower. The dinocyst assemblage suggests that the maximum extent of this Choptank transgression probably covered a significant expanse of the Virginia Piedmont. The Choptank marine silts constrain the age of the unconformably overlying Midlothian gravels to younger than the latter part of the middle Miocene. Previous work has indicated that these gravels also are older than the Pliocene Yorktown Formation. Rare, reworked dinocysts in these Choptank outcrops west of the Fall Line are sourced from older deposits of more than one age. The source could be older updip strata of the lower Eocene Nanjemoy Formation, now erosionally removed. Alternatively, the source could be material referable to the upper Eocene Exmore Formation that resulted from the Chesapeake Bay impact event.

Grounding simulation models with qualitative case studies: Toward a holistic framework to make climate science usable for US public land management

Released October 09, 2018 10:43 EST

2018, Climate Risk Management

Tyler A. Beeton, Shannon M. McNeeley, Brian W. Miller, Dennis S. Ojima

Policies directing agencies and public land managers to incorporate climate change into management face several barriers. These stem, in part, from a disconnect between the information that is produced and the information needs of local resource managers. A disproportionate focus on the natural and physical sciences in climate vulnerability and adaptation assessment obscure understandings of complex social systems and the interactions and feedbacks in social-ecological systems. We use a qualitative case study of bison management on Department of the Interior-managed and tribal lands to explore how a social-science driven Determinants and Analogue Vulnerability Assessment (DAVA) can inform ecological response models, specifically simulation models that account for multiple drivers of change. First, we illustrate how a DAVA approach can help to: 1) identify key processes, entities, and interactions across scales; 2) document local impacts, indicators, and monitoring efforts of drought and climate; and 3) identify major tradeoffs and uncertainties. We then demonstrate how qualitative narratives can inform simulation models by: 1) prioritizing model components included in modeling efforts; 2) framing joint management and climate scenarios; and 3) parameterizing and evaluating model performance. We do this by presenting a conceptual joint agent-based/state-and-transition simulation modeling framework. Simulation models can represent multiple interacting variables and can identify surprising, emergent outcomes that might not be evident from qualitative analysis alone, and we argue that qualitative case studies can ground simulation models in local contexts and help make them more structurally realistic and useful. Together, these can provide a step toward developing actionable climate change adaptation strategies.

Geospatial data mining for digital raster mapping

Released October 09, 2018 10:38 EST

2018, GIScience and Remote Sensing

Bruce K. Wylie, Neal J. Pastick, Joshua J. Picotte, Carol Deering

We performed an in-depth literature survey to identify the most popular data mining approaches that have been applied for raster mapping of ecological parameters through the use of Geographic Information Systems (GIS) and remotely sensed data. Popular data mining approaches included decision trees or “data mining” trees which consist of regression and classification trees, random forests, neural networks, and support vector machines. The advantages of each data mining approach as well as approaches to avoid overfitting are subsequently discussed. We also provide suggestions and examples for the mapping of problematic variables or classes, future or historical projections, and avoidance of model bias. Finally, we address the separate issues of parallel processing, error mapping, and incorporation of “no data” values into modeling processes. Given the improved availability of digital spatial products and remote sensing products, data mining approaches combined with parallel processing potentials should greatly improve the quality and extent of ecological datasets.

Mineralization at oceanic transform faults and fracture zones

Released October 09, 2018 10:38 EST

2019, Book chapter, Transform plate boundaries and fracture zones

Amy Gartman, James Hein

Joao C. Duarte, editor(s)

Mineral formation in the modern oceans can take place over millions of years as a result precipitation from ambient ocean water, or orders of magnitude more rapidly from hydrothermal activity related to magmatic and tectonic processes. Here, we review associations between transform faults and related fracture zones and marine minerals. We define marine transform faults as strike-slip or oblique faults that accommodate lateral offsets along plate boundaries or shifting crustal blocks, and fracture zones as relicts of transform faulting extending beyond mid-ocean ridge offsets. We consider specifically the modern ocean and exclude regions where the transform or fracture has clearly not generated the mineral deposit, such as the Clarion-Clipperton fracture zone manganese nodule field. As a result, the summarized deposits are mainly hydrothermal in origin.

Oceanic transform faulting has rarely been considered of interest for the mineralization and formation of ore deposits; however, there are locations in the modern oceans where transform faults and fracture zones are spatially related to mineral deposits. These occurrences suggest that transform faulting and fracture zones may be linked to mineralization at (A) intersections with other tectonic features, (B) where transform faults begin to resemble rifts through intra-transform crustal thinning, spreading, and the formation of pull-apart basins, and (C) as a result of serpentinization reactions due to exposure of deep-seated rocks by fracturing and faulting.

Hydrodynamics of a tidally‐forced coral reef atoll

Released October 09, 2018 10:33 EST

2018, Journal of Geophysical Research C: Oceans

Rebecca H. Green, Ryan J. Lowe, Mark L. Buckley

The hydrodynamics of a tidally forced semi‐enclosed coral reef atoll (North Scott) at the edge of the continental shelf of northwestern Australia were investigated by combining field observations and numerical modeling. The observations revealed that the spring tidal range outside the atoll reaches 4 m, and as the water level drops below mean sea level, the reef rim surrounding the shallow (~10–15 m) lagoon becomes exposed. During this time, the lagoon can only exchange with the open ocean through two narrow channels, resulting in highly asymmetric water levels and velocities that were most pronounced during spring tide. On average, the ebb tide duration was ~2 hr longer than the flood, with rapid flood velocities in the channel reaching 2 m/s. We applied an unstructured grid model Delft3D‐Flexible Mesh to simulate the atoll hydrodynamics and were able to replicate the asymmetric water levels and complex velocities in the lagoon. The results revealed that at higher tidal stages, a dominant momentum balance exists between the pressure gradient (established by the propagation of the tide on the shelf) and the local flow acceleration of water throughout the interior of the atoll. At lower tidal stages, which coincided with a reversal of the offshore tidal pressure gradient, the lagoon became isolated from offshore dynamics and all momentum terms were negligible. This resulted in a tidally averaged residual westward flow within the lagoon that drove an asymmetric flushing pattern within the atoll, which we propose would be a common flushing mechanism within other tide‐dominated atolls worldwide.

Improving earthquake rupture forecasts using California as a guide

Released October 09, 2018 10:18 EST

2018, Seismological Research Letters

Edward H. Field, Working Group on California Earthquake Probabilities

This article discusses ways in which earthquake rupture forecast models might be improved. Because changes are most easily described in the context of specific models, the third Uniform California Earthquake Rupture Forecast (UCERF3) and its presumed successor, UCERF4, is used as a basis for discussion. Virtually all of the issues and possible improvements discussed are nevertheless general and should therefore be applicable to other regions as well. Two common themes are a need for better epistemic uncertainty representation and the potential utility of physics‐based simulators. Given the large number of possible improvements, coupled with challenges in defining the potential value of each, which will vary among uses, community feedback is invaluable in terms of setting priorities. We should also strive to define more objective valuation metrics.

Assessment of chronic low‐dose elemental and radiological exposures of biota at the Kanab North uranium mine site in the Grand Canyon watershed

Released October 09, 2018 10:11 EST

2018, Integrated Environmental Assessment and Management

Danielle Cleveland, Jo Ellen Hinck, Julia S. Lankton

High‐grade U ore deposits are in various stages of exploitation across the Grand Canyon watershed, yet the effects of U mining on ecological and cultural resources are largely unknown. We characterized the concentrations of Al, As, Bi, Cd, Co, Cu, Fe, Pb, Hg, Mo, Ni, Se, Ag, Tl, Th, U, and Zn, gross alpha and beta activities, and U and Th radioisotopes in soil, vegetation (Hesperostipa comataArtemisia tridentata, Tamarix chinensis), and rodents (Peromyscus maniculatusP. boylii) to waste material at the Kanab North mine, a mine with decades‐long surficial contamination, and compared the concentrations (P < 0.01) to those at a premining site (Canyon Mine). Rodent tissues were also analyzed for radium‐226 and microscopic lesions. Radioactivities and some elemental concentrations (e.g., Co, Pb, U) were greater in the Kanab North mine biological samples than in Canyon Mine biota, indicating a mining‐related elemental signature. Mean rodent Ra‐226 (111 Bq/kg dry weight [dry wt]) was 3 times greater than expected, indicating radioactive disequilibrium. Multiple soil sample U concentrations exceeded a screening benchmark, growth inhibition thresholds for sensitive plants, and an EC20 for a soil arthropod. Lesions associated with metals exposure were also observed more frequently in rodents at Kanab North than those at Canyon Mine but could not be definitively attributed to U mining. Our results indicate that Kanab North biota have taken up U mining‐related elements owing to chronic exposure to surficial contamination. However, no literature‐based effects thresholds for small rodents were exceeded, and only a few soil and vegetation thresholds for sensitive species were exceeded; therefore, adverse effects to biota from U mining‐related elements at Kanab North are unlikely despite chronic exposure. 

Downhole log evidence for the coexistence of structure II gas hydrate and free gas below the bottom simulating reflector in the South China Sea

Released October 09, 2018 10:03 EST

2018, Marine and Petroleum Geology (98) 662-674

Jin Qian, Xiujuan Wang, Timothy S. Collett, Yiqun Guo, Dongju Kang, Jiapeng Jin

Stratigraphic layered pore-filling gas hydrates are identified above the bottom simulating reflector (BSR) using the well log and core data acquired at Sites W11 and W17 during the third gas hydrate drilling expedition conducted by China's Geological Survey/Guangzhou Marine Geological Survey (GMGS3) in the South China Sea. A seismic profile near Site W17, reveal the presence of two BSRs (i.e., double BSR), which we show to relate to zones of structure I gas hydrate (I-BSR) and structure II gas hydrate (II-BSR). Well log data from Site W17 between the “I-BSR” (projected depth of 250 mbsf) and “II-BSR” (projected depth of 330 mbsf) showed anomalous responses for gas hydrate-bearing sediments with high resistivity, high S-wave velocity, and alternating high and low P-wave velocities. Pressure core data support the interpretation that structure II gas hydrate occurs at a depth of 263 mbsf at Site W17. The cross-plot between log-derived neutron and density porosities reveals a free gas-bearing layer at a depth of 258–270 mbsf, suggesting gas hydrate coexists with free gas between the “I-BSR” and the “II-BSR.” Synthetic seismograms generated from the P-wave velocity and density logs further support the presence of free gas in this section. Based on the coexistence of hydrate, free gas and water, the simplified three-phase equation (STPE) was modified to simultaneously estimate free gas and hydrate saturations beneath the “I-BSR” from P-wave and S-wave velocity logs, assuming uniform or patchy distributions of free gas. The estimated free gas and hydrate saturations, together with gas compositions from pressure core samples, collectively indicate that structure II gas hydrate and free gas are interbedded and coexist below the “I-BSR” at Site W17. Our study of the coexistence of gas hydrate and free gas between the double BSR at Site W17 provides new insights into gas hydrate systems in nature that contain more complex gas chemistries.

Mount St. Helens retrospective: Lessons learned since 1980 and remaining challenges

Released October 05, 2018 15:05 EST

2018, Frontiers in Earth Science (6) 1-24

Daniel Dzurisin

Since awakening from a 123-year repose in 1980, Mount St. Helens has provided an opportunity to study changes in crustal magma storage at an active arc volcano—a process of fundamental importance to eruption forecasting and hazards mitigation. There has been considerable progress, but important questions remain unanswered. Was the 1980 eruption triggered by an injection of magma into an upper crustal reservoir? If so, when? How did magma rise into the edifice without producing detectable seismicity deeper than ∼2.5 km or measurable surface deformation beyond the volcano’s north flank? Would precursory activity have been recognized earlier if current monitoring techniques had been available? Despite substantial improvements in monitoring capability, similar questions remain after the dome-forming eruption of 2004–2008. Did additional magma accumulate in the reservoir between the end of the 1980–1986 eruption and the start of the 2004–2008 eruption? If so, when? What is the significance of a relative lull in seismicity and surface deformation for several years prior to the 2004–2008 eruption onset? How did magma reach the surface without producing seismicity deeper than ∼2 km or measurable deformation more than a few hundred meters from the vent? Has the reservoir been replenished since the eruption ended, and is it now primed for the next eruption? What additional precursors, if any, should be expected? This paper addresses these questions, explores possible answers, and identifies unresolved issues in need of additional study. The 1980–1986 and 2004–2008 eruptions could have resulted from second boiling during crystallization of magma long-resident in an upper crustal reservoir, rather than from injection of fresh magma from below. If reservoir pressurization and magma ascent were slow enough, resulting strain might have been accommodated by viscoelastic deformation, without appreciable seismicity or surface deformation, until rising magma entered a brittle regime within 2–2.5 km of the surface. Given the remarkably gas-poor nature of the 2004–2008 dome lava, future eruptive activity might require a relatively long period of quiescence and reservoir pressurization or a large injection of fresh magma—an event that arguably has not occurred since the Kalama eruptive period (C.E. 1479–1720).

Thiamine deficiency in fishes: Causes, consequences, and potential solutions

Released October 05, 2018 14:47 EST

2018, Reviews in Fish Biology and Fisheries

Avril M. Harder, William R. Ardren, Allison N. Evans, Matthew H. Futia, Clifford E. Kraft, J. Ellen Marsden, Catherine A. Richter, Jacques Rinchard, Donald E. Tillitt, Mark R. Christie

Mark R. Christie, editor(s)

Thiamine deficiency complex (TDC) is a disorder resulting from the inability to acquire or retain thiamine (vitamin B1) and has been documented in organisms in aquatic ecosystems ranging from the Baltic Sea to the Laurentian Great Lakes. The biological mechanisms leading to TDC emergence may vary among systems, but in fishes, one common outcome is high mortality among early life stages. Here, we review the causes and consequences of thiamine deficiency in fishes and identify potential solutions. First, we examine the biochemical and physiological roles of thiamine in vertebrates and find that thiamine deficiency consistently results in impaired neurological function across diverse taxa. Next, we review natural producers of thiamine, which include bacteria, fungi, and plants, and suggest that thiamine is not currently limiting for most animal species inhabiting natural aquatic environments. A survey of historic occurrences of thiamine deficiency identifies consumption of a thiamine-degrading enzyme, thiaminase, as the primary explanation for low levels of thiamine in individuals and subsequent onset of TDC. Lastly, we review conservation and management strategies for TDC mitigation ranging from evolutionary rescue to managing for a diverse forage base. As recent evidence suggests occurrences of thiamine deficiency may be increasing in frequency, increased awareness and a better mechanistic understanding of the underlying causes associated with thiamine deficiency may help prevent further population declines.

Improving confidence by embracing uncertainty: A meta-analysis of U.S. hunting values for benefit transfer

Released October 05, 2018 14:42 EST

2018, Ecosystem Services (33) 225-236

Christopher Huber, James Meldrum, Leslie Richardson

Recreational hunting in the United States has traditional and cultural importance, and generates substantial economic benefits to individual hunters themselves. This paper conducts a meta-analysis of existing nonmarket valuation estimates for hunting in the United States to explore sources and implications of variation and uncertainty in these estimates. A multi-level meta-regression model is estimated to forecast point estimates for different hunting contexts, as well as to construct bounds of uncertainty around these estimates. The results and discussion provide insight to practitioners who need to conduct or understand benefit transfer, as well as those particularly interested in the value of hunting in the U.S.

Machine learning for ecosystem services

Released October 05, 2018 14:40 EST

2018, Ecosystem Services (33) 165-174

Simon Willcock, Javier Martinez-Lopez, Danny A.P. Hooftman, Kenneth J. Bagstad, Stefano Balbi, Alessia Marzo, Carlo Prato, Saverio Sciandrello, Giovanni Signorello, Brian Voigt, Ferdinando Villa, James M. Bullock, Ioannis Athanasiadis

Recent developments in machine learning have expanded data-driven modelling (DDM) capabilities, allowing artificial intelligence to infer the behaviour of a system by computing and exploiting correlations between observed variables within it. Machine learning algorithms may enable the use of increasingly available ‘big data’ and assist applying ecosystem service models across scales, analysing and predicting the flows of these services to disaggregated beneficiaries. We use the Weka and ARIES software to produce two examples of DDM: firewood use in South Africa and biodiversity value in Sicily, respectively. Our South African example demonstrates that DDM (64–91% accuracy) can identify the areas where firewood use is within the top quartile with comparable accuracy as conventional modelling techniques (54–77% accuracy). The Sicilian example highlights how DDM can be made more accessible to decision makers, who show both capacity and willingness to engage with uncertainty information. Uncertainty estimates, produced as part of the DDM process, allow decision makers to determine what level of uncertainty is acceptable to them and to use their own expertise for potentially contentious decisions. We conclude that DDM has a clear role to play when modelling ecosystem services, helping produce interdisciplinary models and holistic solutions to complex socio-ecological issues.

Historical eruptions and hazards at Bogoslof volcano, Alaska

Released October 05, 2018 12:05 EST

2018, Scientific Investigations Report 2018-5085

Christopher F. Waythomas, Cheryl E. Cameron

Bogoslof volcano is a submarine volcano in the southern
Bering Sea (53.9272°N, 168.0344°W), located 100 kilometers
(km) west of Dutch Harbor/Unalaska, and 40 km north
of Umnak Island. The volcano has a relatively long history of
scientific investigation and several of its historical eruptions
have been documented during brief visits to the area since the
late 1700s. The purpose of this report is to provide a modern
volcanological perspective on past eruptions of Bogoslof and
to readdress some of the eruptive phenomena described in
historical documents and reports. We also present for the first
time a brief analysis of the hazards posed by Bogoslof eruptions.
While this report was being prepared, Bogoslof volcano
was in an ongoing state of eruptive activity that began in
mid-December 2016. Detectable eruptive activity ended in late
August 2017 and the volcano has remained quiet since then.
Because we have not yet visited Bogoslof Island and have
only a few distal tephra samples from two eruptive events,
we will not discuss in detail the 2016–17 eruptive sequence,
but will provide some information for comparative purposes.
When more detailed data has been collected, a more extensive
review of the 2016–17 Bogoslof eruption should be the subject
of future reports.

Assessment of environmental flows in the middle Verde River watershed, Arizona

Released October 05, 2018 09:04 EST

2018, Fact Sheet 2018-3062

Bruce W. Gungle, Nicholas V. Paretti

This report summarizes analyses of middle Verde River watershed environmental flows detailed in U.S. Geological Survey Scientific Investigations Report 2017-5100, “Preliminary synthesis and assessment of environmental flows in the middle Verde River watershed, Arizona," by N.V. Paretti, A.M.D. Brasher, S.L. Pearlstein, D.M. Skow, B. Gungle, and B.D. Garner.

VS30 at three strong-motion recording stations in Napa and Solano Counties, California—Lovall Valley Road, Broadway Street and Sereno Drive in Vallejo, and Vallejo Fire Station—Calculations determined from S-wave refraction tomography and multichannel analysis of surface waves (Rayleigh and Love)

Released October 04, 2018 16:01 EST

2018, Open-File Report 2018-1162

Joanne H. Chan, Rufus D. Catchings, Mark R. Goldman, Coyn J. Criley

The August 24, 2014, moment magnitude (Mw) 6.0 South Napa earthquake caused an estimated $400 million in structural damage to the City of Napa, California. In 2015, we acquired high-resolution P- and S-wave seismic data near three strong-motion recording stations in Napa and Solano Counties where high peak ground accelerations (PGAs) were recorded during the South Napa earthquake. In this report, we present results from three sites—Lovall Valley Loop Road in Napa County (Northern California Seismic Network station, NCSN N019B) and Broadway Street and Sereno Drive (California Geological Survey station, CGS 68294) and Vallejo Fire Station (National Strong Motion Project station, NSMP 1759) in the City of Vallejo, California. To characterize the recording sites in terms of shallow-depth, shear-wave velocities (VS), we used both surface waves (Rayleigh and Love) and body waves (S-wave) to evaluate the time-averaged VS in the upper 30 meters of the subsurface (VS30). We used two-dimensional (2D) multichannel analysis of surface waves (MASW) to evaluate VS from surface waves, and a refraction tomography inversion algorithm, developed by Hole in 1992, to evaluate VS from the body waves. As determined by the tomography and MASW analysis for Love waves, we found VS30 near the strong-motion recording stations at Lovall Valley Loop Road, Broadway Street and Sereno Drive, and the Vallejo Fire Station to be from 711 meters per second (m/s) to 767 m/s, 455 to 673 m/s, and 490 to 583 m/s, respectively. We found that VS30 determined from Love waves were higher than those determined from Rayleigh waves at the Lovall Valley Loop Road recording site (221 m/s higher) and at the Vallejo Fire Station site (62 and 48 m/s higher); however, VS30 from Love waves was lower than those from Rayleigh waves at the Broadway Street and Sereno Drive site (78 m/s lower). We also found that VS30 varied depending on the number of shot points used in our MASW analysis for both Love and Rayleigh waves. Furthermore, VS30 values determined from S-wave refraction tomography are generally closer to those determined from MASW using Love waves than those determined using Rayleigh waves.

VS30 at three strong-motion recording stations in Napa and Napa County, California—Main Street in downtown Napa, Napa fire station number 3, and Kreuzer Lane—Calculations determined from s-wave refraction tomography and multichannel analysis of surface waves (Rayleigh and Love)

Released October 04, 2018 16:00 EST

2018, Open-File Report 2018-1161

Joanne H. Chan, Rufus D. Catchings, Mark R. Goldman, Coyn J. Criley

The August 24, 2014, moment magnitude (Mw) 6.0 South Napa earthquake caused an estimated $400 million in structural damage to the City of Napa, California. In 2015, we acquired high-resolution P- and S-wave seismic data near three strong-motion recording stations in Napa County where high peak ground accelerations (PGAs) were recorded during the South Napa earthquake. In this report, we present results from three sites—Main Street in Downtown Napa (Northern California Seismic Network station, NCSN N016), Napa Fire Station Number 3 (National Strong Motion Project station, NSMP 1765), and Kreuzer Lane (station KRE, temporary deployment). To characterize the recording sites in terms of shallow-depth shear-wave velocities (VS), we used both surface waves (Rayleigh and Love) and body waves (S-wave) to evaluate the time-averaged VS in the upper 30 meters of the subsurface (VS30). We used two-dimensional multichannel analysis of surface waves (MASW) to evaluate VS from the surface waves, and a refraction tomography inversion algorithm, developed by Hole in 1992, to evaluate VS from the body waves. As determined by the various methods, we found VS30 near the strong-motion recording stations on Main Street in Downtown Napa, Napa Fire Station Number 3, and on Kreuzer Lane to be from 281 meters per second (m/s) to 286 m/s, 297 to 371 m/s, and 885 to 916 m/s, respectively. The VS30 calculated from Love waves were slightly lower (10 m/s) than those calculated from Rayleigh waves at the Downtown Napa location and at Napa Fire Station Number 3 (4 m/s); however, VS30 calculated from Love waves was higher (190 m/s) than those calculated from Rayleigh waves at Kreuzer Lane. We also found that VS30 determined from MASW for both Love and Rayleigh waves varied depending on the number of shots along the profiles, and VS30 was not systematic based on the number of shots used in the analysis. Furthermore, VS30 calculated from S-wave refraction tomography are closer to those determined from MASW calculated from Love waves than from using Rayleigh waves.

Towards globally customizable ecosystem service models

Released October 04, 2018 13:52 EST

2019, Science of the Total Environment (650) 2325-2336

Javier Martinez-Lopez, Kenneth J. Bagstad, Stefano Balbi, Ainhoa Magrach, Brian Voigt, Ioannis Athanasiadis, Marta Pascual, Simon Willcock, Ferdinando Villa

Scientists, stakeholders and decision makers face trade-offs between adopting simple or complex approaches when modeling ecosystem services (ES). Complex approaches may be time- and data-intensive, making them more challenging to implement and difficult to scale, but can produce more accurate and locally specific results. In contrast, simple approaches allow for faster assessments but may sacrifice accuracy and credibility. The ARtificial Intelligence for Ecosystem Services (ARIES) modeling platform has endeavored to provide a spectrum of simple to complex ES models that are readily accessible to a broad range of users. In this paper, we describe a series of five “Tier 1” ES models that users can run anywhere in the world with no user input, while offering the option to easily customize models with context-specific data and parameters. This approach enables rapid ES quantification, as models are automatically adapted to the application context. We provide examples of customized ES assessments at three locations on different continents and demonstrate the use of ARIES' spatial multi-criteria analysis module, which enables spatial prioritization of ES for different beneficiary groups. The models described here use publicly available global- and continental-scale data as defaults. Advanced users can modify data input requirements, model parameters or entire model structures to capitalize on high-resolution data and context-specific model formulations. Data and methods contributed by the research community become part of a growing knowledge base, enabling faster and better ES assessment for users worldwide. By engaging with the ES modeling community to further develop and customize these models based on user needs, spatiotemporal contexts, and scale(s) of analysis, we aim to cover the full arc from simple to complex assessments, minimizing the additional cost to the user when increased complexity and accuracy are needed.

Alternative natural gas contract and pricing structures and incentives of the LNG industry

Released October 04, 2018 12:53 EST

1991, Natural Resources Forum (15) 190-201

Emil Attanasi

Gas conversion to liquefied gas (LNG) and transport by LNG tankers is one option for meeting expanding gas consumption and for gas traded internationally. This paper examines the impact of the traditional gas contract provisions of indefinite pricing, market out price ceilings, and take‐or‐pay requirements on the profitability of LNG projects in the context of markets characterized by price and quantity uncertainty. Simulation experiments are used to examine and calibrate the effects of those provisions. The results provide guidance to operators, host countries and purchasers in structuring such contracts. The paper also assesses prospects of future expansion of world LNG capacity.

Economic implications of petroleum field size distributions

Released October 04, 2018 12:24 EST

1990, Energy Exploration & Exploitation (8) 245-257

Emil Attanasi, Lawrence J. Drew

The unprecedented natural gas price increases in the late 1970's and early 1980's allowed a glimpse of part of the in-situ distribution of natural gas fields that had been hidden by economic truncation. Analysis of those discoveries shows the distribution to be characterized by progressively larger numbers of fields as size category declines. This paper demonstrates the effects of economic truncation for gas fields found in Texas State and Federal offshore areas in the Gulf of Mexico. Economic and policy implications of alternative in-situ field size distribution influence future gas supplies, the associated costs, and petroleum industry activity.

Artelle et al. (2018) miss the science underlying North American wildlife management

Released October 04, 2018 11:17 EST

2018, Science Advances (4) 1-2

Jonathan R. Mawdsley, John F. Organ, Daniel J. Decker, Ann Forstchen, Ronald J. Regan, Shawn J. Riley, Mark S. Boyce, John E. Mcdonald Jr., Chris Dwyer, Shane P. Mahoney

Artelle et al. (2018) conclude that “hallmarks of science” are largely missing from North American wildlife management based on a desk review of selected hunting management plans and related documents found through Internet searches and email requests to state and provincial wildlife agencies. We highlight three fundamental problems that compromise the validity of the conclusions posited: missing information to support selection of “hallmarks of science,” confusion about the roles and nature of science and management, and failure to engage effectively with the scientists and managers actively managing wildlife populations in North America.

Impact of sylvatic plague vaccine on non-target small rodents in grassland ecosystems

Released October 04, 2018 10:54 EST

2018, EcoHealth

Gebbiena M. Bron, Katherine L. D. Richgels, Samuel. Michael D., Julia E. Poje, Faye Lorenzsonn, Jonathan P. Matteson, Jesse T. Boulerice, Jorge E. Osorio, Tonie E. Rocke

Oral vaccination is an emerging management strategy to reduce the prevalence of high impact infectious diseases within wild animal populations. Plague is a flea-borne zoonosis of rodents that often decimates prairie dog (Cynomys spp.) colonies in the western USA. Recently, an oral sylvatic plague vaccine (SPV) was developed to protect prairie dogs from plague and aid recovery of the endangered black-footed ferret (Mustela nigripes). Although oral vaccination programs are targeted toward specific species, field distribution of vaccine-laden baits can result in vaccine uptake by non-target animals and unintended indirect effects. We assessed the impact of SPV on non-target rodents at paired vaccine and placebo-treated prairie dog colonies in four US states from 2013 to 2015. Bait consumption by non-target rodents was high (70.8%, n = 3113), but anti-plague antibody development on vaccine plots was low (23.7%, n = 266). In addition, no significant differences were noted in combined deer mice (Peromyscus maniculatus) and western harvest mouse (Reithrodontomys megalotis) abundance or community evenness and richness of non-target rodents between vaccine-treated and placebo plots. In our 3-year field study, we could not detect a significant positive or negative effect of SPV application on non-target rodents.

Embryonic effects of an environmentally relevant PCB mixture in the domestic chicken

Released October 04, 2018 10:50 EST

2018, Environmental Toxicology and Chemistry (37) 2513-2522

Mary Ann Ottinger, Emma T. Lavoie, Mary E. B. Bohannon, Allegra M. Marcel, Anna E. Tschiffely, Kara B. Duffy, Moira A. McKernan, Nichola Thompson, H. Kasen Whitehouse, Kimya Davani, Marci Strauss, Donald E. Tillitt, Joshua Lipton, Karen M. Dean

Studies were conducted to develop methods to assess the effects of a complex mixture of polychlorinated biphenyls (PCBs) in the domestic chicken (Gallus domesticus). Treatments were administered by egg injection to compare embryonic effects of an environmentally relevant PCB congener mixture in the domestic chicken over a range of doses. Chicken eggs were injected with the PCB mixture with a profile similar to that found in avian eggs collected on the upper Hudson River, New York, USA, at doses that spanned 0 to 98 μg/g egg. Eggs were hatched in the laboratory to ascertain hatching success. In the domestic chicken, the median lethal dose was 0.3 μg/g. These data demonstrate adverse effects of an environmentally relevant PCB mixture and provide the basis for further work using in vitro and other models to characterize the potential risk to avian populations. 

Chronic toxicity of 4-nonylphenol to two unionid mussels in water-only exposures

Released October 04, 2018 10:46 EST

2018, Bulletin of Environmental Contamination and Toxicology (101) 423-427

Chris D. Ivey, Ning Wang, David Alvarez, Edward J. Hammer, Candice R. Bauer

Limited studies indicate that mussels are generally insensitive to organic chemicals; however, these studies were conducted in acute or short-term exposures, and little is known about the chronic sensitivity of mussels to organic chemicals. We evaluated the chronic (28 days) toxicity of 4-nonylphenol (4-NP) to two commonly tested species of mussels: fatmucket (Lampsilis siliquoidea) and rainbow mussel (Villosa iris). By the end of the 28 days chronic exposures, mean survival was ≥93% in all treatments, but the mean dry weight and biomass of mussels at the highest exposure concentrations were significantly reduced relative to the control. The 20% effect concentrations were similar between the two species. When compared to all other tested species, fatmucket and rainbow mussels are among the top four most sensitive species to 4-NP. However, U.S. Environmental Protection Agency chronic water quality criterion of 6.6 μg 4-NP/L should protect the two mussel species.

High microscale variability in Raman thermal maturity estimates from shale organic matter

Released October 04, 2018 10:41 EST

2018, International Journal of Coal Geology (199) 1-9

Aaron M. Jubb, Palma J. Botterell, Justin E. Birdwell, Robert C. Burruss, Paul C. Hackley, Brett J. Valentine, Javin J. Hatcherian, Stephen A. Wilson

Raman spectroscopy has recently received attention as a means to estimate thermal maturity of organic matter in petroleum generating source rocks to complement more traditional approaches such as vitrinite reflectance and programmed pyrolysis. While many studies have observed positive correlations between source rock thermal maturity and Raman spectral parameters, little attention has been given to the degree of variation in the Raman response across individual organic grains, especially for shales or mudrocks with highly dispersed organic matter. Here the spatial variation in Raman estimates of thermal maturity within individual organic grains is assessed from shales from the Boquillas, Marcellus, Niobrara, and Woodford Formations. The thermal maturity parameters extracted from Raman spectra can vary widely across distances of ≤5 μm within the same organic grain. These results illustrate the high degree of chemical heterogeneity inherent to the organic matter within these source rocks. Additionally, the spatial pattern of the Raman parameters, as revealed by 2D Raman mapping, imply that organic matter structure is influenced by associations with mineral surfaces within the surrounding rock matrix. Chemical heterogeneity and matrix effects directly impact the Raman response from these types of materials and thus the extracted thermal maturity estimate. These findings highlight the care which must be adopted when making Raman measurements of organic matter within source rock matrices, especially for samples which feature highly dispersed, heterogeneous organic matter as found in petroliferous mudrocks.

Wrangling distributed computing for high-throughput environmental science: An introduction to HTCondor

Released October 04, 2018 10:35 EST

2018, PLOS Computational Biology (14) 1-8

Richard A. Erickson, Michael N. Fienen, S. Grace McCalla, Emily L. Weiser, Melvin L. Bower, Jonathan M. Knudson, Greg Thain

Biologists and environmental scientists now routinely solve computational problems that were unimaginable a generation ago. Examples include processing geospatial data, analyzing -omics data, and running large-scale simulations. Conventional desktop computing cannot handle these tasks when they are large, and high-performance computing is not always available nor the most appropriate solution for all computationally intense problems. High-throughput computing (HTC) is one method for handling computationally intense research. In contrast to high-performance computing, which uses a single "supercomputer," HTC can distribute tasks over many computers (e.g., idle desktop computers, dedicated servers, or cloud-based resources). HTC facilities exist at many academic and government institutes and are relatively easy to create from commodity hardware. Additionally, consortia such as Open Science Grid facilitate HTC, and commercial entities sell cloud-based solutions for researchers who lack HTC at their institution. We provide an introduction to HTC for biologists and environmental scientists. Our examples from biology and the environmental sciences use HTCondor, an open source HTC system.

Regional patterns in the geochemistry of oil-field water, southern San Joaquin Valley, California, USA

Released October 04, 2018 10:31 EST

2018, Applied Geochemistry (98) 127-140

Peter B. McMahon, Justin Kulongoski, Avner Vengosh, Isabelle M. Cozzarelli, Matthew K. Landon, Yousif K. Kharaka, Janice M. Gillespie, Tracy Davis

Chemical and isotopic data for water co-extracted with hydrocarbons in oil and gas fields are commonly used to examine the source of the formation water and possible impacts on groundwater in areas of oil and gas development. Understanding the geochemical variability of oil-field water could help to evaluate its origin and delineate possible contamination of shallow aquifers in cases where oil-field water is released to the environment. Here we report geochemical and multiple isotope (H, C, O, Sr, Ra) data from 22 oil wells, three sources of produced water that are disposed of in injection wells, and two surface disposal ponds in four oil fields in the southern San Joaquin Valley, California (Fruitvale, Lost Hills, North and South Belridge). Correlations between Cl and δ18O, as well as other ions, and gradual increases in salinity with depth, indicate dilution of one or more saline end-members by meteoric water. The saline end-members, represented by deep samples (610 m–2621 m) in three oil-bearing zones, are characterized by NaCl composition, near-seawater Cl concentrations (median 20,000 mg/L), enriched δ18OH2O (median 3.4‰), high ammonium(up to 460 mg-N/L), and relatively high radium activity (226Ra+228Ra = 12.3 Bq/L). The deepest sample has low Na/Cl (0.74), high Ca/Mg (5.0), and low 87Sr/86Sr (0.7063), whereas the shallower samples have higher Na/Cl (0.86–1.2), Ca/Mg near 1, and higher 87Sr/86Sr (∼0.7083). The data are consistent with an original seawater source being modified by various depth and lithology dependent diagenetic processes. Dilution by meteoric water occurs naturally on the east side of the valley, and in association with water-injectionactivities on the west side. Meteoric-water flushing, particularly on the east side, results in lower solute concentrations (minimum total dissolved solids 2730 mg/L) and total radium (minimum 0.27 Bq/L) in oil-field water, and promotes biodegradation of dissolved organic carbon and hydrocarbon gases like propane. Acetate concentrations and δ13C of dissolved inorganic carbon indicate biogenic methane production occurs in some shallow oil zones. Natural and human processes produce substantial variability in the geochemistry of oil-field water that should be considered when evaluating mixing between oil-field waters and groundwater. The variability could result in uncertainty as to detecting the potential source and impact of oil-field water on groundwater.

Fuels guide and database for intact and invaded big sagebrush (Artemisia tridentata) ecological sites—User manual

Released October 04, 2018 06:45 EST

2018, Data Series 1048

Douglas J. Shinneman, Justin L. Welty, Robert S. Arkle, David S. Pilliod, Nancy F. Glenn, Susan K. McIlroy, Anne S. Halford

The Fuels Guide and Database (FGD) is intended to provide fuel loading and vegetation information for big sagebrush (Artemisia tridentata) ecological sites in the Morley Nelson Snake River Birds of Prey National Conservation Area (hereinafter the NCA) in southern Idaho. Sagebrush ecosystems in the NCA and throughout much of the Great Basin are highly influenced by non-native plants that alter successional trajectories and promote frequent wildfires, especially due to fine-fuel loadings that are highly variable over time and space. These dynamic fuel conditions can increase uncertainty when attempting to project fire risk and fire behavior. The FGD was developed to help quantify and assess these dynamic fuel loadings, and it provides access to fuels data across a range of conditions, from relatively intact sagebrush-bunchgrass communities to degraded communities dominated by nonnative annual grasses and forbs. The FGD can be queried for a variety of environmental conditions, and it provides tabular data, reports, and photographic records of fuels based on user queries. This report describes the FGD, including overall data content and data-collection methods, as well as instructions for installing and using the database.

Overview of the oxygen isotope systematics of land snails from North America

Released October 03, 2018 10:46 EST

2018, Quaternary Research

Yurena Yanes, Nasser M. Al-Qattan, Jason A. Rech, Jeffrey S. Pigati, Justin P. Dodd, Jeffrey C. Nekola

Continental paleoclimate proxies with near-global coverage are rare. Land snail δ18O is one of the few proxies abundant in Quaternary sediments ranging from the tropics to the high Arctic tundra. However, its application in paleoclimatology remains difficult, attributable in part to limitations in published calibration studies. Here we present shell δ18O of modern small (<10 mm) snails across North America, from Florida (30°N) to Manitoba (58°N), to examine the main climatic controls on shell δ18O at a coarse scale. This transect is augmented by published δ18O values, which expand our coverage from Jamaica (18°N) to Alaska (64°N). Results indicate that shell δ18O primarily tracks the average annual precipitation δ18O. Shell δ18O increases 0.5–0.7‰ for every 1‰ increase in precipitation δ18O, and 0.3–0.7‰ for every 1°C increase in temperature. These relationships hold true when all taxa are included regardless of body size (ranging from ~1.6 to ~58 mm), ecology (herbivores, omnivores, and carnivores), or behavior (variable seasonal active periods and mobility habits). Future isotopic investigations should include calibration studies in tropical and high-latitude settings, arid environments, and along altitudinal gradients to test if the near linear relationship between shell and meteoric precipitation δ18O observed on a continental scale remains significant.

2018 hurricane and wildfire supplemental funding: USGS recovery activities

Released October 02, 2018 18:15 EST

2018, Fact Sheet 2018-3063

Jo Ellen Hinck, Joseph Stachyra

The Additional Supplemental Appropriations for Disaster Relief Requirements Act, 2018 (P.L. 115-123), was signed by the President on February 9, 2018. This funding provided $42.2 million to the U.S. Geological Survey (USGS) for equipment repair and replacement, high-resolution elevation data collection in both hurricane- and wildfire-impacted areas, and scientific studies and assessments that will support recovery and rebuilding decisions in the wake of Hurricanes Harvey, Irma, and Maria and the California Wildfires.

Altitude of the potentiometric surface, 2000–15, and historical water-level changes in the Memphis aquifer in the Memphis area, Tennessee

Released October 02, 2018 15:04 EST

2018, Scientific Investigations Map 3415

James A. Kingsbury

The Memphis and Fort Pillow aquifers are the principal sources of water for municipal, industrial, and commercial uses in the Memphis area. About 207 million gallons per day of groundwater were withdrawn in Shelby County, Tennessee, from both aquifers in 2010 for these uses, with most of the water coming from the Memphis aquifer. The U.S. Geological Survey, in cooperation with the City of Memphis, Memphis Light, Gas and Water Division, collects groundwater-level data in the Memphis area and periodically prepares potentiometric-surface maps for the Memphis aquifer to assess conditions in this regionally important water supply aquifer. This report presents the altitudes of the potentiometric surface of water in wells screened in the Memphis aquifer based on water-level measurements made in the fall of 2000, 2005, 2010, and 2015 and describes historical water-level changes in the Memphis aquifer at key observation wells in the Memphis area. The Memphis area is about 1,500 square miles and includes all of Shelby County and parts of Tipton and Fayette Counties in Tennessee, parts of DeSoto and Marshall Counties in Mississippi, and part of Crittenden County in Arkansas.

Revised technical implementation plan for the ShakeAlert system—An earthquake early warning system for the West Coast of the United States

Released October 02, 2018 14:56 EST

2018, Open-File Report 2018-1155

Douglas D. Given, Richard M. Allen, Annemarie S. Baltay, Paul Bodin, Elizabeth S. Cochran, Kenneth Creager, Lind S. Gee, Egill Hauksson, Thomas H. Heaton, Margaret Hellweg, Jessica R. Murray, Valerie I. Thomas, Douglas Toomey, Thomas S. Yelin

The U.S. Geological Survey (USGS), along with partner organizations, has developed an earthquake early warning (EEW) system called ShakeAlert for the highest risk areas of the United States: namely, California, Oregon, and Washington. The purpose of the system is to reduce the impact of earthquakes and save lives and property by providing alerts to institutional users and the public. Using networks of ground-motion sensors and sophisticated computer algorithms, ShakeAlert can detect an earthquake seconds after it begins, calculate its location and magnitude, and estimate the resulting intensity of shaking. Alerts can then be sent to people and systems that may experience damaging shaking, allowing them to take appropriate protective actions. Depending on the user’s distance from the earthquake, alerts may be delivered before, during, or after the arrival of strong shaking.

ShakeAlert is built on the foundation of the sensor networks and data processing infrastructure of the USGS-led Advanced National Seismic System. However, these networks were not originally designed for EEW; old equip­ment needs to be updated and new stations must be added to construct EEW-capable networks. The ShakeAlert data-processing infrastructure includes redundant servers that are geographically distributed at monitoring centers in Seattle, Washington, as well as Menlo Park, Berkeley, and Pasadena in California. Three data-processing layers collect raw ground-motion data from field stations (data layer), analyze these data to estimate the area and intensity of the resulting shaking (production layer), and publish alert products as appropriate for end users (alert layer). The alert layer can support thousands of institutional users and alert redistributors, but the USGS does not have the mission, infrastructure, or expertise to perform public notifications and is therefore recruiting technology enablers from the private sector. Additionally, ShakeAlert will coordinate with both public and private partners to accomplish consistent and ongoing public communication, education, and outreach.

The estimated cost of completing the ShakeAlert infrastructure and sensor networks is \$39.4 million and has an estimated annual operation and maintenance cost of \$28.6 million per year. Building a highly reliable data telemetry infrastructure would cost another \$20.5 million and operating this telemetry system would add \$49.8 million per year; however, these costs could be reduced if project partners provide bandwidth on existing systems.

Hydrologic characteristics and water quality of headwater streams and wetlands at the Allegheny Portage Railroad National Historic Site, Summit area, Blair and Cambria Counties, Pennsylvania, 2014–16

Released October 02, 2018 14:15 EST

2018, Open-File Report 2018-1125

Charles A. Cravotta III, Daniel G. Galeone, Kathy A. Penrod

The Allegheny Portage Railroad National Historic Site (ALPO) in Blair and Cambria Counties, Pennsylvania, protects historic features of the first railroad portage over the Allegheny Front and the first railroad tunnel in the United States. This report, which was completed by the U.S. Geological Survey in cooperation with the National Park Service, summarizes water resources in the headwaters of the Blair Gap Run and Bradley Run watersheds at the ALPO Summit area during 2014–16. These new baseline data fill an existing gap in knowledge and may be helpful to evaluate potential changes in the hydrologic characteristics of streams and associated wetlands at the Summit area.

Results of synoptic water-quality surveys and continuous stage records at two streamgages near the headwaters of Blair Gap Run and Bradley Run indicate that the headwater streams of the ALPO Summit area are perennial but have different water-quality characteristics. The water sampled in the headwaters of Blair Gap Run had pH that ranged from acidic to near neutral, combined with elevated concentrations of dissolved solids, mainly sulfate, chloride, and sodium. These characteristics can be attributed to drainage from legacy coal mines and runoff from nearby roads treated with deicing salt. More than once during the study, the chloride and associated contaminant concentrations in tributaries of Blair Gap Run exceeded chronic thresholds for protection of freshwater aquatic organisms. In contrast, the water quality at tributaries of Bradley Run in the Summit area was characterized by near-neutral pH and relatively low concentrations of dissolved constituents, which met criteria for protection of freshwater aquatic life. By comparison, the deep groundwater discharged as abandoned mine drainage to Sugar Run from the Argyle Stone Bridge Mine, which underlies the Summit area, had acidic pH and elevated concentrations of sulfate and metals, which exceeded chronic and acute thresholds for aquatic life.

Data on shallow groundwater levels in piezometers at two wetlands in the Summit area, which were monitored during spring through fall of 2016, indicate downward hydraulic gradients (higher water level in shallow piezometer than in deeper piezometer) and potential for local groundwater recharge during rainfall events, particularly in the summer and fall seasons. The wetlands in the upland area (wetland 3, at altitude 2,370 feet NAVD 88) near the divide between Blair Gap Run and Bradley Run between the Lemon House and Picnic Area, exhibited a consistent downward gradient from spring through fall of 2016. The associated surface seepage at wetland 3 dried up in the summer of 2016. In contrast, the wetlands in the adjoining valley (wetland 6, at altitude 2,198 feet NAVD 88) in the northwestern Summit area exhibited upward hydraulic gradients in the spring and produced continuous seepage. Despite downward gradients during summer and fall, the seepage associated with wetland 6 sustained perennial conditions in the Bradley Run drainage through the summer of 2016.

Differences in groundwater altitudes and associated water quality among the surface water, shallow groundwater, and deep groundwater in the Summit area imply that the surface water and shallow groundwater in the Summit area could recharge the groundwater of the underlying coal mines. Seasonally upward and downward vertical gradients in the near-surface soil and bedrock at wetland 6, and unimpaired water quality in the Bradley Run headwaters, are consistent with a perched water table and local hydrology that is influenced by local recharge. Persistent downward gradients and impaired water quality at wetland 3 and the adjacent headwaters seeps and tributaries of Blair Gap Run could be attributed to subsidence and drainage from shallow coalbeds (Upper Freeport, seam E) and associated mine workings in that area; however, the underlying deep coal mine pool (Lower Kittanning, seam B), which is hundreds of feet below the surface, does not appear to affect the hydrologic characteristics of the headwater streams and wetlands in the Summit area.

Current research in land, water, and agroecosystems: ASABE journals 2017 year in review

Released October 01, 2018 15:52 EST

2018, Transactions of the ASABE

Kyle R. Douglas-Mankin

This article highlights current research into land and water resources, agroecosystems, and agricultural production systems published by the Natural Resources and Environmental Systems (NRES) community of ASABE journals (Transactions of the ASABE and Applied Engineering in Agriculture) in 2017. This article reviews the context, scope, and key results of the published articles and perhaps more importantly recommends areas for increased research attention. Experimental and modeling advances were described in hydrology, agroecosystems, climate-change effects, soil erosion, irrigation, drainage, forest resources, livestock systems, natural treatment systems, international water issues, and water quality topic areas. Three special collections were published (International Watershed Technology, Crop Modeling to Optimize Water Use, and Advances in Drainage). Other focal areas included 14 articles relating to livestock waste management, 13 concerning irrigated agricultural systems, 8 addressing climate change effects on land and water resources, and 16 on various aspects of soil erosion measurement and modeling. Building on the articles reviewed from 2017 and toward a vision of future agroecosystems research, the NRES community of ASABE journals strives to grow its role in making new knowledge accessible to sustain agricultural and natural systems in a changing world. In this vane, recommendations for future research direction are discussed with an emphasis on increased application of remote sensing data to agroecosystems research, improved assessment of agroecosystem resiliency and vulnerability to land and climate change, development of integrated models of agroecosystem services, meeting stubborn water management challenges in agricultural production systems, and focusing on publishing fully reproducible model results.

Impacts of temporal revisit designs on the power to detect trend with a linear mixed model: An application to long-term monitoring of Sierra Nevada lakes

Released October 01, 2018 14:36 EST

2018, Ecological Indicators (93) 847-855

Leigh Ann H. Starcevich, Kathryn M. Irvine, Andrea M. Heard

Long-term ecological monitoring programs often use linear mixed models to estimate trend in an ecological indicator sampled across large landscapes. A linear mixed model is versatile for estimating a linear trend in time as well as components of spatial and temporal variationin the case of unbalanced data structures, which are common in complex monitoring designs where limited sampling effort must be optimized over time and space. A power analysis was used to inform a lake chemistry monitoring design, including selecting the most appropriate temporal revisit design. Pilot data from surveys of lakes across large wilderness national parks (Sequoia, Kings Canyon, and Yosemite national parks) were used to obtain variance components for a Monte Carlo power simulation. Using a linear mixed model for a range of temporal revisit designs, sample sizes, and trend magnitudes, we evaluated the power to detect trend, the trend test size, and the relative bias of trend coefficient estimates for four continuous and normally distributed indicators. Contrary to prior research based on large-sample approximations that identified a single panel of sites visited annually as the revisit design generating the highest power, we found that the power to detect a 12-year trend based on the Wald t-test from a linear mixed model may be optimized by obtaining unbalanced data sets with limited to no annual replication. We emphasize the importance of examining variance composition, sample size, and the power and size of the trend test with Monte Carlo simulation when allocating sampling effort over time and space.

Multidirectional abundance shifts among North American birds and the relative influence of multifaceted climate factors

Released October 01, 2018 14:24 EST

2018, Global Change Biology (23) 3610-3622

Qiongyu Huang, John R. Sauer, Ralph O. Dubayah

Shifts in species distributions are major fingerprint of climate change. Examining changes in species abundance structures at a continental scale enables robust evaluation of climate change influences, but few studies have conducted these evaluations due to limited data and methodological constraints. In this study, we estimate temporal changes in abundance from North American Breeding Bird Survey data at the scale of physiographic strata to examine the relative influence of different components of climatic factors and evaluate the hypothesis that shifting species distributions are multidirectional in resident bird species in North America. We quantify the direction and velocity of the abundance shifts of 57 permanent resident birds over 44 years using a centroid analysis. For species with significant abundance shifts in the centroid analysis, we conduct a more intensive correlative analysis to identify climate components most strongly associated with composite change of abundance within strata. Our analysis focus on two contrasts: the relative importance of climate extremes vs. averages, and of temperature vs. precipitation in strength of association with abundance change. Our study shows that 36 species had significant abundance shifts over the study period. The average velocity of the centroid is 5.89 km·yr−1. The shifted distance on average covers 259 km, 9% of range extent. Our results strongly suggest that the climate change fingerprint in studied avian distributions is multidirectional. Among 6 directions with significant abundance shifts, the northwestward shift was observed in the largest number of species (n = 13). The temperature/average climate model consistently has greater predictive ability than the precipitation/extreme climate model in explaining strata‐level abundance change. Our study shows heterogeneous avian responses to recent environmental changes. It highlights needs for more species‐specific approaches to examine contributing factors to recent distributional changes and for comprehensive conservation planning for climate change adaptation.

Unusual foraging observations associated with seabird die-offs in Alaska

Released October 01, 2018 14:08 EST

2018, Marine Ornithology: Journal of Seabird Research and Conservation (46) 149-153

Bryce Robinson, Lucas H. DeCicco, James A. Johnson, Daniel R. Ruthrauff

We report the first documentation of off-water foraging by the Fork-tailed Storm-Petrel Oceanodroma furcata and Short-tailed Shearwater Ardenna tenuirostris, a behavior not previously documented in any member of the families Hydrobatidae or Procellariidae. Over a two-week period in September 2016, we regularly observed individuals of these species over land on an extensive intertidal zone on the Bristol Bay coast of the Alaska Peninsula. We documented irregular feeding behaviors by storm-petrels, including pattering over shallow water and sand, digging into sand to uncover food items, and feeding on beach-cast fish. We revisited the site in August 2017 and did not observe storm-petrels, but we observed four shearwaters feeding on a beach-cast fish. The aberrant feeding behaviors, paucity of stomach contents and emaciated body condition of salvaged and collected birds, together with patterns between bird occurrence and wind speed and direction, indicate to us that these birds were blown to shore while weakened by food stress or compromised health. We further suggest that these aberrant feeding behaviors may be related to massive seabird die-offs that occurred in this region during 2014–2016, die-offs in which Forktailed Storm-Petrels have heretofore not been reported as a species affected by this phenomenon.

Preliminary evaluation of behavioral response of nesting waterbirds to small unmanned aircraft flight

Released October 01, 2018 11:38 EST

2018, Waterbirds (41) 326-331

Kaitlyn Reintsma, Peter C. McGowan, Carl R. Callahan, Tom Collier, David Gray, Jeffery D. Sullivan, Diann J. Prosser

Small unmanned aircraft systems present an emerging technology with the potential to survey colonial waterbird populations while reducing disturbance in comparison to traditional ground counts. Recent research with these systems has been performed on some colonially nesting avian species; however, none have focused on wading bird species. During 2015–2016, this study tested the behavioral response of a mixed-species rookery (Cattle Egret (Bubulcus ibis), Snowy Egret (Egretta thula), Glossy Ibis (Plegadis falcinellus) and a groundnesting colony of Common Terns (Sterna hirundo)) in shrub habitat to small unmanned aircraft system flights at 12 m, 15 m, 30 m, and 50 m. Even at the lowest altitudes, the birds either showed no reaction or acclimated within 60 sec of the fly-over. Conversely, physically entering the colony to conduct ground surveys resulted in all Common Terns flushing from their nests beginning when the observer was 50 m away and required significantly more time in the colony overall: ~30–60 min vs. ~3–7 min with the small unmanned aircraft system. While this study focuses only on the behavioral response of nesting birds and not comparison of count estimates, these results provide preliminary evidence that small unmanned aircraft systems provide the potential to monitor colonial nesting bird populations while minimizing disturbance to the colony.

Simulation of groundwater flow, 1895–2010, and effects of additional groundwater withdrawals on future stream base flow in the Elkhorn and Loup River Basins, central Nebraska—Phase three

Released October 01, 2018 11:33 EST

2018, Scientific Investigations Report 2018-5106

Amanda T. Flynn, Jennifer S. Stanton

The U.S. Geological Survey, in cooperation with the Lewis and Clark, Lower Elkhorn, Lower Loup, Lower Platte North, Lower Niobrara, Middle Niobrara, Upper Elkhorn, and the Upper Loup Natural Resources Districts, designed a study to refine the spatial and temporal discretization of a previously modeled area. This updated study focused on a 30,000-square-mile area of the High Plains aquifer and constructed regional groundwater-flow models to evaluate the effects of groundwater withdrawal on stream base flow in the Elkhorn and Loup River Basins, Nebraska. The model was calibrated to match groundwater-level and base-flow data from the stream-aquifer system from pre-1940 through 2010 (including predevelopment [pre-1895], early development [1895–1940], and historical development [1940 through 2010] conditions) using an automated parameter-estimation method. The calibrated model then was used to simulate hypothetical development conditions (2011 through 2060). Predicted changes to stream base flow based on simulated changes to groundwater withdrawal will aid in developing strategies for management of hydrologically connected water supplies.

Additional wells were simulated throughout the model domain and pumped for 50 years to assess the effect of wells on aquifer depletions, including stream base flow. The percentage of withdrawal for each well after 50 years, which was compensated by aquifer reductions to stream base flow, storage, or evapotranspiration, was computed and mapped. These depletions are influenced by aquifer properties, time, and distance from the well. Stream base-flow depletion results showed that the closer the added well was to a stream, the greatest the effect on the stream base flow. Areas of stream base-flow depletion percentages greater than 80 percent were generally within 1 mile (mi) from the stream. The distance increased to 6 mi near the confluence of the Dismal and Middle Loup Rivers, and the North Loup and Calamus Rivers. The percentage of stream base-flow depletion decreased as the distance from the stream increased. Areas more than 10 mi from the stream generally had a stream base-flow depletion of 10 percent or less. Evapotranspiration depletion was largest in areas closest to streams, specifically in the Elkhorn River watershed. It was also larger in areas of interdunal wetlands within the Sand Hills. Evapotranspiration depletion was negligible in areas greater than 5 mi from a stream, with the exception of interdunal areas in Cherry, Grant, and Arthur Counties. The storage depletion percentage increased as the distance from a stream increased. Storage depletion was largest in areas between streams. Areas experiencing the smallest amount of storage depletion were adjacent to streams. Calibrated model outputs and streamflow depletion analysis are publicly available online.

Accuracy of the simulations is affected by input data limitations, system simplifications, assumptions, and resources available at the time of the simulation construction and calibration. Most of the important limitations relate either to data used as simulation inputs or to data used to estimate simulation inputs. Development of the regional simulations focused on generalized hydrogeologic characteristics within the study area and did not attempt to describe variations important to local-scale conditions. These simulations are most appropriate for analyzing groundwater-management scenarios for large areas and during long periods and are not suitable for analysis of small areas or short periods.

Occupancy modeling species–environment relationships with non‐ignorable survey designs

Released October 01, 2018 11:16 EST

2018, Ecological Applications (28) 1616-1625

Kathryn M. Irvine, Thomas J. Rodhouse, Wilson J. Wright, Anthony R. Olsen

Statistical models supporting inferences about species occurrence patterns in relation to environmental gradients are fundamental to ecology and conservation biology. A common implicit assumption is that the sampling design is ignorable and does not need to be formally accounted for in analyses. The analyst assumes data are representative of the desired population and statistical modeling proceeds. However, if data sets from probability and non‐probability surveys are combined or unequal selection probabilities are used, the design may be non‐ignorable. We outline the use of pseudo‐maximum likelihood estimation for site‐occupancy models to account for such non‐ignorable survey designs. This estimation method accounts for the survey design by properly weighting the pseudo‐likelihood equation. In our empirical example, legacy and newer randomly selected locations were surveyed for bats to bridge a historic statewide effort with an ongoing nationwide program. We provide a worked example using bat acoustic detection/non‐detection data and show how analysts can diagnose whether their design is ignorable. Using simulations we assessed whether our approach is viable for modeling data sets composed of sites contributed outside of a probability design. Pseudo‐maximum likelihood estimates differed from the usual maximum likelihood occupancy estimates for some bat species. Using simulations we show the maximum likelihood estimator of species–environment relationships with non‐ignorable sampling designs was biased, whereas the pseudo‐likelihood estimator was design unbiased. However, in our simulation study the designs composed of a large proportion of legacy or non‐probability sites resulted in estimation issues for standard errors. These issues were likely a result of highly variable weights confounded by small sample sizes (5% or 10% sampling intensity and four revisits). Aggregating data sets from multiple sources logically supports larger sample sizes and potentially increases spatial extents for statistical inferences. Our results suggest that ignoring the mechanism for how locations were selected for data collection (e.g., the sampling design) could result in erroneous model‐based conclusions. Therefore, in order to ensure robust and defensible recommendations for evidence‐based conservation decision‐making, the survey design information in addition to the data themselves must be available for analysts. Details for constructing the weights used in estimation and code for implementation are provided.

Floristic and climatic reconstructions of two Lower Cretaceous successions from Peru

Released October 01, 2018 11:02 EST

2018, Palynology (42) 420-433

Paula J. Mejia-Velasquez, Steven R. Manchester, Carlos A. Jaramillo, Luiz Quiroz, Lucas B. Fortini

Climate during the Early Cretaceous in tropical South America has often been reconstructed as arid. However, some areas seem to have been humid. We reconstructed the floristic composition of two tropical stratigraphic successions in Peru using quantitative palynology (rarefied species richness and abundance), and used the abundance of aridity vs. humidity indicator species to infer the predominant climate conditions of this region. The Berriasian to Hauterivian La Merced succession was dominated by fern spores and was predominantly humid. The Albian Aguas Frias succession yielded rich palynofloras, with 127 species, and also indicates predominantly humid conditions. These results support the hypothesis that the west margin of South America was humid during the Early Cretaceous, thus improving the tropical climate reconstructions during the Cretaceous severe global warming episodes.

Juke Box trench: A valuable archive of late Pleistocene and Holocene stratigraphy in the Bonneville basin, Utah

Released October 01, 2018 10:51 EST

2018, Miscellaneous Publication 18-1

Charles G. Oviatt, Jeffrey S. Pigati, David B. Madsen, David E. Rhode, Jordon Bright

A backhoe trench in deposits of Pleistocene Lake Bonneville and Holocene wetlands below the mouth of Juke Box Cave, near Wendover, Utah, provides an excellent view of the late Pleistocene and Holocene geologic history of the area. The following stratigraphic units are exposed (ascending): preBonneville gravel (fluvial or lacustrine) and oolitic sand (ages greater than 30,000 yr B.P.); Lake Bonneville marl (30,000 to ~13,000 yr B.P.); an unconformity stratigraphically above the Bonneville marl marked by lacustrine gravel of probable Gilbert-episode age (~11,500 yr B.P.); and poorly sorted sand and carbonate mud deposited in post-Bonneville spring-fed wetlands. The wetland deposits include layers of poorly sorted sand, peat composed of bulrush remains and other organic-rich muds, and the Mazama volcanic ash (~7600 yr B.P.). Four calibrated 14C ages suggest the wetland deposits span nearly the entire Holocene, from about 10,700 to at least 1200 yr B.P. The spring and wetland are now dry.

Induced earthquake and liquefaction hazards in Oklahoma, USA: Constraints from InSAR

Released October 01, 2018 10:48 EST

2018, Remote Sensing of Environment (218) 1-12

William D. Barnhart, William L. Yeck, Daniel E. McNamara

Oklahoma experienced three earthquakes of Mw5.0 or greater in 2016: the 13-Feb. Fairview earthquake (Mw5.1), the 03-Sep. Pawnee earthquake (Mw5.8), and the 07-Nov. Cushing earthquake (Mw5.0). These events are the first earthquakes in the state exceeding Mw5.0 since the 2011 Mw5.7 Prague earthquake and likely result from wide-scale deep fluid-injection. We use interferometric synthetic aperture radar (InSAR) observations to quantify the magnitude and location of surface deformation associated with these three events, determine the depth ranges of fault slip, and assess the spatial relationship between fault slip and well-calibrated mainshock and aftershock locations. We also include newly reported, calibrated event locations for the Cushing earthquake. We find that the Pawnee earthquake ruptured within the crystalline basement with the shallowest slip occurring at depths of 3.1–4.3 km. We find a similar, though shallower, crystalline basement source for the Cushing earthquake with a minimum depth to slip of 1.6–2.3 km. Despite the smaller magnitude of the Cushing earthquake, it generated anomalously high ground motions and damage compared to the larger Pawnee and Fairview earthquakes. We postulate that the shallow source of the Cushing earthquakes provides one explanation for the higher than expected ground motions. The Fairview earthquake generated no detectable co-seismic displacements, which is consistent with a relatively deep earthquake source (~8.5 km). We do, however, identify a 16 km stretch of floodplain where widespread liquefaction occurred in response to the Fairview earthquake, and where 30 gas production wells were exposed to surface displacements exceeding 5 cm. Consequently, the depth to crystalline basement, which limits the depth of injection-induced earthquakes in Oklahoma, and the potential for liquefaction are important factors in assessing shaking risk in the central United States.

Economics, helium, and the U.S. Federal Helium Reserve: Summary and outlook

Released October 01, 2018 10:44 EST

2018, Natural Resources Research (27) 455-477

Steven T. Anderson

In 2017, disruptions in the global supply of helium reminded consumers, distributors, and policy makers that the global helium supply chain lacks flexibility, and that attempts to increase production from the U.S. Federal Helium Reserve (the FHR) may not be able to compensate for the loss of one of the few major producers in the world. Issues with U.S. and global markets for helium include inelastic demand, economic availability of helium only as a byproduct, only 4–5 major producers, helium’s propensity to escape earth’s crust, an ongoing absence of storage facilities comparable to the FHR, and a lack of consequences for the venting of helium. The complex combination of these economic, physical, and regulatory issues is unique to helium, and determining helium’s practical availability goes far beyond estimating the technically accessible volume of underground resources. Although most of these issues have been analyzed since helium was recognized to be a valuable mineral commodity in the early 1900s, very few economic models have been developed that adequately consider the unique characteristics of helium and helium markets. In particular, there is a notable lack of recent empirical work to estimate the responsiveness of helium demand, supply, prices, and trade patterns to the ongoing drawdown and sale of helium reserves stored in the FHR. In general, existing models of helium either do not account for an oligopoly controlling supply, or they do not evaluate potential helium extraction and storage programs based on an intertemporal maximization of the value of the resource. Such models could be of very limited use to decision makers. This review found only one working paper with a helium market model that has incorporated both of these vital considerations. That and other economic studies along similar lines could be very useful in helping inform current helium policy discussions and decisions.

Quantifying climate sensitivity and climate-driven change in North American amphibian communities

Released October 01, 2018 10:43 EST

2018, Nature Communications (9) 1-15

David A.W. Miller, Evan H. Campbell Grant, Erin L. Muths, Staci M. Amburgey, Michael J. Adams, Maxwell B. Joseph, J. Hardin Waddle, Pieter T.J. Johnson, Maureen E. Ryan, Benedikt R. Schmidt, Daniel L. Calhoun, Courtney L. Davis, Robert N. Fisher, David M. Green, Blake R. Hossack, Tracy A.G. Rittenhouse, Susan Walls, Larissa L. Bailey, Sam S. Cruickshank, Gary M. Fellers, Thomas A. Gorman, Carola A. Haas, Ward Hughson, David S. Pilliod, Steven J. Price, Andrew M. Ray, Walter Sadinski, Daniel Saenz, William J. Barichivich, Adrianne B, Brand, Cheryl S. Brehme, Rosi Dagit, Katy S. Delaney, Brad M. Glorioso, Lee B. Kats, Patrick M. Kleeman, Christopher Pearl, Carlton J. Rochester, Seth P. D. Riley, Mark F. Roth, Brent Sigafus

Changing climate will impact species’ ranges only when environmental variability directly impacts the demography of local populations. However, measurement of demographic responses to climate change has largely been limited to single species and locations. Here we show that amphibian communities are responsive to climatic variability, using >500,000 time-series observations for 81 species across 86 North American study areas. The effect of climate on local colonization and persistence probabilities varies among eco-regions and depends on local climate, species life-histories, and taxonomic classification. We found that local species richness is most sensitive to changes in water availability during breeding and changes in winter conditions. Based on the relationships we measure, recent changes in climate cannot explain why local species richness of North American amphibians has rapidly declined. However, changing climate does explain why some populations are declining faster than others. Our results provide important insights into how amphibians respond to climate and a general framework for measuring climate impacts on species richness.

Delineation of contributing areas for 2017 pumping conditions to selected wells in Ingham County, Michigan

Released October 01, 2018 10:15 EST

2018, Open-File Report 2018-1133

Carol L. Luukkonen

As part of local wellhead protection area programs, areas
contributing water to production wells need to be periodically
updated because groundwater-flow paths depend in part on
the stresses to the groundwater-flow system. A steady-state
groundwater-flow model that was constructed in 2009 was
updated to reflect recent (2017) pumping conditions in the
Lansing and East Lansing area in the Tri-County region, Michigan.
For this current (2017) study, withdrawals from selected
production wells were updated, and the existing model calibration
under the new pumping conditions was checked. Results
of flow simulations indicate that 10-year time-of-travel areas
cover approximately 25 square miles and 40-year time-oftravel
areas cover approximately 51 square miles.

Time series of high-resolution images enhances efforts to monitor post-fire condition and recovery, Waldo Canyon fire, Colorado, USA

Released September 28, 2018 13:04 EST

2018, International Journal of Wildland Fire

Melanie Vanderhoof, Clifton Burt, Todd J. Hawbaker

Interpretations of post-fire condition and rates of vegetation recovery can influence management priorities, actions and perception of latent risks from landslides and floods. In this study, we used the Waldo Canyon fire (2012, Colorado Springs, Colorado, USA) as a case study to explore how a time series (2011–2016) of high-resolution images can be used to delineate burn extent and severity, as well as quantify post-fire vegetation recovery. We applied an object-based approach to map burn severity and vegetation recovery using Worldview-2, Worldview-3 and QuickBird-2 imagery. The burned area was classified as 51% high, 20% moderate and 29% low burn-severity. Across the burn extent, the shrub cover class showed a rapid recovery, resprouting vigorously within 1 year, whereas 4 years post-fire, areas previously dominated by conifers were divided approximately equally between being classified as dominated by quaking aspen saplings with herbaceous species in the understorey or minimally recovered. Relative to using a pixel-based Normalised Difference Vegetation Index (NDVI), our object-based approach showed higher rates of revegetation. High-resolution imagery can provide an effective means to monitor post-fire site conditions and complement more prevalent efforts with moderate- and coarse-resolution sensors.

Late-season movement and habitat use by Oregon spotted frogs (Rana pretiosa) in Oregon, USA

Released September 28, 2018 12:56 EST

2018, Copeia (106) 539-549

Christopher Pearl, Brome Mccreary, Jennifer Rowe, Michael J. Adams

Many amphibians use multiple habitats across seasons. Information on seasonal habitat use, movement between seasonal habitat types, and habitats that may be particularly valuable is important to conservation and management. We used radio-telemetry to study late-season movement and habitat use by Oregon Spotted Frog (Rana pretiosa) at nine sites from four populations along the Cascade Mountains in Oregon. Movement rates declined with date and were the lowest at the end of tracking in December and January. Frogs across our sites used vegetated shallows in late summer and early fall. In fall, frogs used a range of habitat types, and at several sites moved to distinctive habitats such as springs, interstices in lava rock, and semi-terrestrial beaver channels. Distance between first and last tracking location was <250 m for 84.5% (49/58) of frogs, ranged up to 1145 m, and was greater for frogs in ditch habitats than those not in ditches. Distinctive features like springs or semi-terrestrial retreats can host multiple frogs and may represent particularly valuable wintering habitat for R. pretiosa in some sites in their Oregon range.

Efficient delineation of nested depression hierarchy in digital elevation models for hydrological analysis using level-set method

Released September 28, 2018 12:54 EST

2018, Journal of the American Water Resources Association

Qiusheng Wu, Charles R. Lane, Lei Wang, Melanie Vanderhoof, Jay R. Christensen, Hongxing Liu

In terrain analysis and hydrological modeling, surface depressions (or sinks) in a digital elevation model (DEM) are commonly treated as artifacts and thus filled and removed to create a depressionless DEM. Various algorithms have been developed to identify and fill depressions in DEMs during the past decades. However, few studies have attempted to delineate and quantify the nested hierarchy of actual depressions, which can provide crucial information for characterizing surface hydrologic connectivity and simulating the fill‐merge‐spill hydrological process. In this paper, we present an innovative and efficient algorithm for delineating and quantifying nested depressions in DEMs using the level‐set method based on graph theory. The proposed level‐set method emulates water level decreasing from the spill point along the depression boundary to the lowest point at the bottom of a depression. By tracing the dynamic topological changes (i.e., depression splitting/merging) within a compound depression, the level‐set method can construct topological graphs and derive geometric properties of the nested depressions. The experimental results of two fine‐resolution Light Detection and Ranging‐derived DEMs show that the raster‐based level‐set algorithm is much more efficient (~150 times faster) than the vector‐based contour tree method. The proposed level‐set algorithm has great potential for being applied to large‐scale ecohydrological analysis and watershed modeling.

A spatially discrete, integral projection model and its application to invasive carp

Released September 28, 2018 12:51 EST

2018, Ecological Modelling (387) 163-171

Richard A. Erickson, Eric E. Eager, Patrick Kocovsky, David C. Glover, Jahn L. Kallis, K. R. Long

Natural resource managers and ecologists often desire an understanding of spatial dynamics such as migration, dispersion, and meta-population dynamics. Network-node models can capture these salient features. Additionally, the state-variable used with many species may be appropriately modeled as a continuous variable (e.g., length) and management activities sometimes can only target individuals of certain sizes. Integral projection models (IPMs) can capture this life history characteristic and allow for the examination of size-specific management. We combined an IPM with a network-node model to capture both of these salient features. We then demonstrated how this model could be used to understand and manage populations of invasive species focusing on grass carp as an example. Grass carp disrupt ecosystems outside of their native range and have spread around much of the world, including North America. The impacts of grass carp include adversely changing aquatic plant communities, which in turn affect a wide range of endpoints ranging from water quality to waterfowl recruitment. We specifically examined two theoretical systems using parameters from the literature. First, we modeled a lake with two tributaries and examined how modified sterile males could be used as a control tool. We found that modified sterile males may be a feasible control tool to limit population growth. Second, we modeled a series of river pools and examined how harvest and deterrents could be used to decrease the risk of expanding grass carp's range within a river system. Within this system, we also compared the impacts of size specific harvest and uniform harvest across all sizes. We found that targeting the largest, spawning populations may be more important than targeting the populations close to the invasion front for reducing the risk of spreading grass carp. We also demonstrate that size of harvested fish was important for controlling populations.

Spatial distribution of halogen oxides in the plume of Mount Pagan volcano, Mariana Islands

Released September 28, 2018 12:49 EST

2018, Geophysical Research Letters

Christoph Kern, John Lyons

Halogens are emitted from volcanoes primarily as hydrogen halides (HCl, HF, HBr, and HI). Upon mixing with the atmosphere, chlorine and bromine species are partially converted to the halogen oxides OClO and BrO. Here we report on the spatial distribution of BrO and OClO in the gas plume emitted from Mount Pagan volcano, Northern Mariana Islands. We found enhanced BrO/SO2 ratios near the plume edges and a lack of OClO in the plume's core. Our results highlight the importance of in‐mixing of atmospheric oxidants for halogen oxide formation. They indicate that OClO can only be formed after most bromide dissolved in plume aerosols has been released to the gas phase. We conclude that Mount Pagan's gas emissions originated from a shallow magma body and were transported to the surface along dry degassing pathways and that the volcano's halogen emissions likely had significant impact on the oxidation capacity of the downwind atmosphere.

Depth to basement and thickness of unconsolidated sediments for the western United States—Initial estimates for layers of the U.S. Geological Survey National Crustal Model

Released September 28, 2018 12:00 EST

2018, Open-File Report 2018-1115

Anjana K. Shah, Oliver S. Boyd

We present numeric grids containing estimates of the thickness of unconsolidated sediments and depth to the pre-Cenozoic
basement for the western United States. Values for these grids were combined and integrated from previous studies or derived
directly from gravity analyses. The grids are provided with 1-kilometer grid-node spacing in ScienceBase (https://www.sciencebase.gov).
These layers may be updated as results from new studies become available.

Groundwater contributions to excessive algal growth in the East Fork Carson River, Carson Valley, west-central Nevada, 2010 and 2012

Released September 28, 2018 09:17 EST

2018, Scientific Investigations Report 2018-5102

Nancy L. Alvarez, Randy A. Pahl, Michael R. Rosen

Excessive algal growth and low dissolved oxygen concentrations were observed during low streamflow conditions during summer months along a 5,800-foot reach of the East Fork Carson River in Carson Valley, west-central Nevada. Algal growth from nutrient enrichment of a stream reduces aquatic diversity, threatens fish ecology and stream health, and can be a recreational nuisance. In response to concerns that groundwater discharging to the 5,800-foot reach of the East Fork Carson River may be a source of nutrients to the stream, the U.S. Geological Survey, in cooperation with the Carson Water Subconservancy District and the Nevada Division of Environmental Protection, conducted studies during the summers of 2010 and 2012 to gain an improved understanding of the contributions of nutrients to the stream from groundwater, characterize algal conditions and algal effects on water quality, assess potential sources of nitrate in groundwater discharging to the stream, and evaluate nitrate reduction in groundwater from denitrification.

A reconnaissance study in the summer of 2010 along the 5,800-foot study reach located a subreach with clear evidence of nutrient-rich groundwater discharging to the stream. At the subreach, nitrate plus nitrite (referred to hereafter as nitrate) concentrations in groundwater discharging to the stream were high (average 2.75 milligrams per liter as nitrogen) along the right bank. The stream at this location had the highest stream nitrate concentrations (average 0.056 milligrams per liter as nitrogen) compared to other locations upstream and downstream of the subreach. As a result, the 2012 study focused on a 405-foot subreach of the East Fork Carson River centered where results from the 2010 study found the highest stream and groundwater concentrations of nitrate, as well as the greatest observed contributions of groundwater discharge to the stream.

Groundwater nutrient concentrations were much higher than stream nutrient concentrations during the summer of 2012 during low streamflow conditions at the 405-foot subreach of the East Fork Carson River. Average groundwater nitrate and orthophosphate concentrations along the right bank of the 405‑foot subreach were 9 and 12 times higher, respectively, than in the stream at this subreach. Groundwater discharge rates to the study reach based on different methods varied from 0.09 to 1.2 cubic feet per second per mile. Estimated groundwater discharge rates to the right bank of the study subreach were used to calculate groundwater nutrient load estimates to the subreach right bank, which were found to be low when compared to stream nutrient loads.

Elevated algal biomass levels above nuisance thresholds were observed during the summers of 2010 and 2012. The study reach was characterized as mesotrophic-eutrophic during the 2010 study and eutrophic during the 2012 study. The presence of algae caused daily dissolved oxygen and pH fluctuations in the stream, resulting in exceedances of the State of Nevada water-quality standards owing to low dissolved oxygen concentrations and high pH concentrations, although the standards might not have been applicable during 2012 because of extremely low streamflow.

The addition of nutrients to the stream from the constant supply in groundwater discharge sustains the growth of algae during low streamflow conditions. In the summer when streamflow is low or very low, nutrient-rich groundwater discharge enters the stream through the sediment-water interface at the streambed. Because the attached algae is thick and stream velocity is low, the nutrient-rich water pools at the sediment-water interface. Higher nutrient concentrations at the streambed create a favorable microenvironment for algae attached to the substrate to consume available nutrients from the groundwater before the groundwater mixes with overlying stream water.

The source of nitrate in groundwater in this subreach is anthropogenic because nitrate concentrations are greater than background groundwater nitrate concentrations in Douglas County, high groundwater nitrate concentrations are only found at the right bank of the stream near a housing development, and organic wastewater compounds indicative of human-derived sources were also detected in groundwater wells on the right bank of the stream. Nitrogen and oxygen isotope concentrations of nitrate in shallow groundwater were used to determine the specific source of the nitrate, but the isotopic values indicated denitrification was occurring. Further investigation is needed to determine the specific anthropogenic source of the nitrate in the groundwater because the denitrification present in all samples obscures the original source of nitrogen.

Assessment of continuous oil and gas resources of the Putumayo-Oriente-Marañón Basin Province of Colombia, Ecuador, and Perú, 2018

Released September 27, 2018 17:05 EST

2018, Fact Sheet 2018-3048

Christopher J. Schenk, Tracey J. Mercier, Janet K. Pitman, Thomas M. Finn, Phuong A. Le, Stephanie B. Gaswirth, Kristen R. Marra, Heidi M. Leathers-Miller

Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 1.1 billion barrels of oil and 793 billion cubic feet of gas in the Putumayo-Oriente-Marañón Basin Province of Colombia, Ecuador, and Perú.

A new modeling approach to prioritize riparian restoration to reduce sediment loading in two Virginia river basins

Released September 27, 2018 14:26 EST

2018, Environmental Management (62) 721-739

Lisa N. Scott, Amy M. Villamagna, Paul L. Angermeier

Human impact, particularly land cover changes (e.g., agriculture, construction) increase erosion and sediment loading into streams. Benthic species are negatively affected by silt deposition that coats and embeds stream substrate. Given that riparian buffers are effective sediment filters, riparian restoration is increasingly implemented by conservation groups to protect stream habitats. Limited funding and a multitude of impaired streams warrant the need for cost-effective prioritization of potential restoration actions. We created a decision-support framework for conservation agencies and aquatic resource managers to prioritize riparian restoration efforts. Our framework integrates GIS data and field surveys into a statistical model to predict instream silt from estimates of upland soil loss and riparian filtration capacity. We focus specifically on prioritizing sites in upper sections of the Roanoke and Nottoway river basins (Virginia, US) based on observed records of Roanoke logperch (Percina rex), an imperiled sediment-sensitive species. Our statistical approach examines soil characteristics, land cover, precipitation, topography, and annual soil loss estimates from the empirically derived Revised Universal Soil Loss Equation, combined with land cover-based riparian filtration capacity as potential stream habitat predictors. We found riparian filtration capacity to be a significant predictor of silt cover, while precipitation was a significant predictor of embeddedness. Spatial scale was also a factor, in that spatial variance in silt cover and embeddedness was more accurately predicted at smaller spatial extents. Ultimately, our model can be used as a prioritization tool for mitigating high siltation areas, or for protecting low soil erosion areas.

Diel fledging patterns among grassland passerines: Relative impacts of energetics and predation risk

Released September 27, 2018 14:22 EST

2018, The Auk (135) 1100-1112

Christine Ribic, Christoph Ng, Nicola Koper, Kevin Ellison, Pamela J. Pietz, David J. Rugg

The time of day that nestlings fledge from a nest is thought to be shaped by predation risk and energetics. To minimize predation risk, fledging is predicted to start as early in the day as possible so that nestlings can maximize time outside the nest to find a safe place to stay before nightfall. Fledging times are predicted to be tightly grouped and to not be affected by the number of nestlings, given that all nestlings are responding to the same relative risk of predation. Conversely, energetic considerations predict that fledging time of day should vary so that nestlings can maximize energy intake before having to forage for themselves. However, data to evaluate the relative importance of these drivers in grassland birds are scarce because of the difficulty of observing nestlings as they fledge. We used nest surveillance video from 178 nests to evaluate how the initiation and duration of fledging varied among 7 grassland passerine species, as well as by the number of nestlings in the nest and fledging date. Fledging initiation varied most strongly by species, with some effects of date. Across species, the median start time of fledging was 4.55 hr after sunrise. Fledging before the solstice started ∼30 min earlier compared to fledging at or after the solstice. Fledging duration increased with number of nestlings in the nest and was spread over >1 day in 21% of nests. While our results primarily supported the hypothesis that fledging is motivated by energetic considerations, additional data on basic life history traits and behavior will be needed to fully understand how fledging grassland birds balance energetics against predation risk.

Sensor suite: The Albuquerque Seismological Laboratory Instrumentation Testing Suite

Released September 27, 2018 14:20 EST

2018, Seismological Research Letters

A. Kearns, Adam Ringler, James Holland, Tyler Storm, David Wilson, Robert E. Anthony

To standardize parameters used in seismometer testing and calibration and to make these algorithms accessible to the seismological community, we have developed a new seismometer testing software package called Albuquerque Seismological Laboratory (ASL) Sensor Test Suite. This software is written in Java and makes use of Seismological Exchange for Earthquake Data (SEED) format. Our goal is not to be all‐inclusive but instead to focus on a few of the instrumentation tests we view as critical when verifying a sensor’s performance. The tests include self‐noise, relative azimuth, relative gain, and estimation of the poles and zeros. For the self‐noise and the relative azimuth, we also include three‐component versions of these tests to allow for the case of sensors with potentially different orientations (e.g., boreholes). The software has been made available on GitHub with the hope that it will be useful for other seismologists who need to quickly verify various sensor parameters without having to write their own versions of the algorithms. Furthermore, by using a common platform and processing algorithms, it becomes possible to compare results among different tests with similar processing methods being used for both.

Effects of leg flags on nest survival of four species of Arctic‐breeding shorebirds

Released September 27, 2018 14:17 EST

2018, Journal of Field Ornithology (89) 287-297

Emily L. Weiser, Richard B. Lanctot, Stephen C. Brown, H. River Gates, Rebecca L. Bentzen, Megan L. Boldenow, Jenny A. Cunningham, Andrew C. Doll, Tyrone F. Donnelly, Willow B. English, Samantha E. Franks, Kristen Grond, Patrick Herzog, Brooke L. Hill, Steve J. Kendall, Eunbi Kwon, David B. Lank, Joseph R. Liebezeit, Jennie Rausch, Sarah T. Saalfeld, Audrey R. Taylor, David H. Ward, Paul F. Woodard, Brett K. Sandercock

Marking wild birds is an integral part of many field studies. However, if marks affect the vital rates or behavior of marked individuals, any conclusions reached by a study might be biased relative to the general population. Leg bands have rarely been found to have negative effects on birds and are frequently used to mark individuals. Leg flags, which are larger, heavier, and might produce more drag than bands, are commonly used on shorebirds and can help improve resighting rates. However, no one to date has assessed the possible effects of leg flags on the demographic performance of shorebirds. At seven sites in Arctic Alaska and western Canada, we marked individuals and monitored nest survival of four species of Arctic‐breeding shorebirds, including Semipalmated Sandpipers (Calidris pusilla), Western Sandpipers (C. mauri), Red‐necked Phalaropes (Phalaropus lobatus), and Red Phalaropes (P. fulicarius). We used a daily nest survival model in a Bayesian framework to test for effects of leg flags, relative to birds with only bands, on daily survival rates of 1952 nests. We found no evidence of a difference in nest survival between birds with flags and those with only bands. Our results suggest, therefore, that leg flags have little effect on the nest success of Arctic‐breeding sandpipers and phalaropes. Additional studies are needed, however, to evaluate the possible effects of flags on shorebirds that use other habitats and on survival rates of adults and chicks.

Effects of urban stormwater and iron‐enhanced sand filtration on Daphnia magna and Pimephales promelas

Released September 27, 2018 14:12 EST

2018, Environmental Toxicology and Chemistry (37) 2645-2659

Benjamin M. Westerhoff, David J. Fairbairn, Mark L. Ferrey, Adriana Matilla, Jordan Kunkel, Sarah M. Elliott, Richard L. Kiesling, Dustin Woodruff, Heiko L. Schoenfuss

Urban stormwater is an important but incompletely characterized contributor to surface‐water toxicity. The present study used 5 bioassays of 2 model organisms (Daphnia magnaand fathead minnow, Pimephales promelas) to investigate stormwater toxicity and mitigation by full‐scale iron‐enhanced sand filters (IESFs). Stormwater samples were collected from major stormwater conveyances and full‐scale IESFs during 4 seasonal events (winter snowmelt and spring, early summer, and late summer rainfalls) and analyzed for a diverse range of contaminants of emerging concern including pharmaceuticals, personal care products, industrial chemicals, and pesticides. Concurrently, stormwater samples were collected for toxicity testing. Seasonality appeared more influential and consistent than site type for most bioassays. Typically, biological consequences were least in early summer and greatest in late summer and winter. In contrast with the unimproved and occasionally reduced biological outcomes in IESF‐treated and late summer samples, water chemistry indicated that numbers and total concentrations of detected organic chemicals, metals, and nutrients were reduced in late summer and in IESF‐treated stormwater samples. Some potent toxicants showed more specific seasonality (e.g., high concentrations of polycyclic aromatic hydrocarbons and industrial compounds in winter, pesticides in early summer and spring, flame retardants in late summer), which may have influenced outcomes. Potential explanations for insignificant or unexpected stormwater treatment outcomes include confounding effects of complex stormwater matrices, IESF nutrient removal, and, less likely, unmonitored toxicants. 

Practical approaches to maximizing the resolution of sparker seismic reflection data

Released September 27, 2018 14:09 EST

2018, Marine Geophysical Research

Jared Kluesner, Daniel Brothers, Patrick E. Hart, Nathaniel Miller, Gerry Hatcher

Sparkers are a type of sound source widely used by the marine seismic community to provide high-resolution imagery of the shallow sub-bottom (i.e., < 1000 m). Although sparkers are relatively simple, inexpensive, and high-frequency (100–2500 Hz) sources, they have several potential pitfalls due to their complicated and unpredictable signature. In this study we quantify the source characteristics of several sparker systems and develop a suite of simple processing approaches for both single channel and multi-channel sparker data. In all cases, the results show improved vertical resolution and reflection coherency. Correcting for small static variations in multi-channel seismic (MCS) data is a critical first step to preserve the broad frequency content during stacking, and to reduce the shot-to-shot variability of outgoing and incoming signals. Application of predictive deconvolution to static-corrected, post-stack traces suppresses short-path multiples and restores the latent high-resolution reflection patterns. However, if shot-to-shot source signatures are recorded directly, pre-stack deterministic deconvolution followed by post-stack predictive deconvolution produces the most robust results. Processing sparker data without broadband techniques results in less confident or completely missed interpretations when compared to the broadband equivalent. If processed correctly, marine sparker data can provide exceptional sub-bottom imagery that rivals other more repeatable marine seismic sources (e.g., high-frequency air-guns).

Williston Basin groundwater availability, United States and Canada

Released September 27, 2018 12:55 EST

2018, Fact Sheet 2018-3046

Joanna N. Thamke, Andrew J. Long, Kyle W. Davis

The Williston Basin contains important oil and gas resources for the Nation. Freshwater supplies are limited in this semiarid area, and oil and gas development can require large volumes of freshwater. Groundwater is the primary source of water for many water users in the Williston Basin, so to better understand these resources, the U.S. Geological Survey (USGS) assessed the groundwater availability in this area. The final phase of this assessment included a computer model that simulates how groundwater flows in the aquifer systems and simulates how changes in water use and natural conditions may affect the water resources. These results provide a tool for land and water-resource managers to determine how water can be used for multiple purposes in the Williston Basin. For additional information about this assessment and more in-depth descriptions and results, see Long and others (2018).

Local factors associated with on‐host flea distributions on prairie dog colonies

Released September 27, 2018 12:20 EST

2018, Ecology and Evolution (8) 8951-8972

Robin E. Russell, Rachel C. Abbott, Daniel W. Tripp, Tonie E. Rocke

Outbreaks of plague, a flea‐vectored bacterial disease, occur periodically in prairie dog populations in the western United States. In order to understand the conditions that are conducive to plague outbreaks and potentially predict spatial and temporal variations in risk, it is important to understand the factors associated with flea abundance and distribution that may lead to plague outbreaks. We collected and identified 20,041 fleas from 6,542 individual prairie dogs of four different species over a 4‐year period along a latitudinal gradient from Texas to Montana. We assessed local climate and other factors associated with flea prevalence and abundance, as well as the incidence of plague outbreaks. Oropsylla hirsuta, a prairie dog specialist flea, and Pulex simulans, a generalist flea species, were the most common fleas found on our pairs. High elevation pairs in Wyoming and Utah had distinct flea communities compared with the rest of the study pairs. The incidence of prairie dogs with Yersinia pestis detections in fleas was low (n = 64 prairie dogs with positive fleas out of 5,024 samples from 4,218 individual prairie dogs). The results of our regression models indicate that many factors are associated with the presence of fleas. In general, flea abundance (number of fleas on hosts) is higher during plague outbreaks, lower when prairie dogs are more abundant, and reaches peak levels when climate and weather variables are at intermediate levels. Changing climate conditions will likely affect aspects of both flea and host communities, including population densities and species composition, which may lead to changes in plague dynamics. Our results support the hypothesis that local conditions, including host, vector, and environmental factors, influence the likelihood of plague outbreaks, and that predicting changes to plague dynamics under climate change scenarios will have to consider both host and vector responses to local factors.

Temperature regimes, growth, and food consumption for female and male adult walleye in Lake Huron and Lake Erie: a bioenergetics analysis

Released September 27, 2018 12:14 EST

2018, Canadian Journal of Fisheries and Aquatic Sciences (75) 1573-1586

Charles P. Madenjian, Todd A. Hayden, Tyler B. Peat, Christopher Vandergoot, David G. Fielder, Ann Marie Gorman, Steven A. Pothoven, John M. Dettmers, Steven J. Cooke, Yingming Zhao, Charles C. Krueger

Bioenergetics modeling was used to assess the relative importance of food availability and water temperature in determining walleye (Sander vitreus) growth. Temperature regimes experienced by both female and male adult walleye in three basins of Lake Huron and in Lake Erie were determined by use of surgically implanted temperature loggers and acoustic telemetry. Temperatures experienced by walleye were higher in Lake Erie than in Lake Huron. Walleye from Lake Erie grew at nearly double the rate of walleye from Lake Huron, and mass at age for adult females averaged about 50% greater than that for adult males in both lakes. Food consumption rate for an average adult walleye in Lake Erie was nearly twice as high as that in Lake Huron. Interbasin and interlake variability in temperature regimes accounted for a moderate degree of variability in walleye growth. We concluded that the driver for faster growth in Lake Erie compared with Lake Huron was higher food availability in Lake Erie compared with Lake Huron. The sex difference in temperature regimes explained 15% of the sex difference in Lake Erie walleye growth.

U.S. Geological Survey input-data forms for the assessment of the Upper Jurassic Haynesville Formation, U.S. Gulf Coast, 2016

Released September 27, 2018 11:30 EST

2018, Open-File Report 2018-1130

Stanley T. Paxton, Janet K. Pitman, Scott A. Kinney, Nicholas J. Gianoutsos, Ofori N. Pearson, Katherine J. Whidden, Russell F. Dubiel, Christopher J. Schenk, Lauri A. Burke, Timothy R. Klett, Heidi M. Leathers-Miller, Tracey J. Mercier, Seth S. Haines, Brian A. Varela, Phuong A. Le, Thomas M. Finn, Stephanie B. Gaswirth, Sarah J. Hawkins, Kristen R. Marra, Marilyn E. Tennyson


In 2016, the U.S. Geological Survey (USGS) completed an updated assessment of undiscovered, technically recoverable oil and gas resources in the Upper Jurassic Haynesville Formation of the onshore U.S. Gulf Coast Province (Paxton and others, 2017). The Haynesville Formation was assessed using both the standard continuous (unconventional) and conventional methodologies established by the USGS for four assessment units (AUs): (1) Haynesville Western Shelf Carbonate Gas and Oil AU, (2) Haynesville Eastern Shelf Sandstone and Carbonate Oil and Gas AU, (3) Haynesville Shale Continuous Gas AU, and (4) Haynesville Shale Peripheral Continuous Gas AU. The revised assessment resulted in total estimated mean resources of 1.1 billion barrels of oil, 195.8 trillion cubic feet of gas, and 866 million barrels of natural gas liquids. The purpose of this report is to provide supplemental documentation of the input parameters used in the USGS 2016 Haynesville Formation assessment.

U.S. Geological Survey input-data forms for the assessment of the Upper Jurassic Bossier Formation, U.S. Gulf Coast, 2016

Released September 27, 2018 11:30 EST

2018, Open-File Report 2018-1134

Stanley T. Paxton, Janet K. Pitman, Scott A. Kinney, Nicholas J. Gianoutsos, Ofori N. Pearson, Katherine J. Whidden, Russell F. Dubiel, Christopher J. Schenk, Lauri A. Burke, Timothy R. Klett, Heidi M. Leathers-Miller, Tracey J. Mercier, Seth S. Haines, Brian A. Varela, Phuong A. Le, Thomas M. Finn, Stephanie B. Gaswirth, Sarah J. Hawkins, Kristen R. Marra, Marilyn E. Tennyson


In 2016, the U.S. Geological Survey (USGS) completed an updated assessment of undiscovered, technically recoverable oil and gas resources in the Upper Jurassic Bossier Formation of the onshore U.S. Gulf Coast Province (Paxton and others, 2017). The Bossier Formation was assessed using both the standard continuous (unconventional) and conventional methodologies established by the USGS for three assessment units (AUs): (1) Bossier Eastern Shelf Sandstone Gas and Oil AU, (2) Bossier Western Shelf Sandstone Gas AU, and (3) Bossier Shale Continuous Gas AU. A fourth assessment unit, the Upper Jurassic Downdip Continuous Gas AU, was also defined but was not quantitatively assessed because of limited well data within the extent of the AU. The revised assessment resulted in total estimated mean resources of 2.9 billion barrels of oil, 108.6 trillion cubic feet of gas, and 1.1 billion barrels of natural gas liquids. The purpose of this report is to provide supplemental documentation of the input parameters used in the USGS 2016 Bossier Formation assessment.

Assessment of oil and gas resources in the Upper Jurassic Haynesville and Bossier Formations, U.S. Gulf Coast, 2016

Released September 27, 2018 11:30 EST

2018, Open-File Report 2018-1135

Stanley T. Paxton

The U.S. Geological Survey completed a geology-based assessment of undiscovered, technically recoverable oil and gas resources in the Haynesville and Bossier Formations of the onshore and State waters portion of the U.S. Gulf Coast region. Haynesville Formation conventional oil and gas production began in the late 1930s, whereas Bossier Formation production began in the early 1970s. Production of continuous gas resources from both formations began in 2006–7. Most of the current activity is focused on natural gas production from Haynesville and Bossier shales using horizontal wells and hydraulic fracturing. In 2016, the U.S. Geological Survey assessed technically recoverable mean resources of 4 billion barrels of oil and 304.4 trillion cubic feet of gas in the Haynesville and Bossier Formations of the onshore and State waters portion of the U.S. Gulf Coast region. 

Groundwater availability of the Williston Basin, United States and Canada

Released September 27, 2018 07:56 EST

2018, Professional Paper 1841

Andrew J. Long, Joanna N. Thamke, Kyle W. Davis, Timothy T. Bartos

Executive Summary

The Williston Basin of the Northern Great Plains is a sedimentary basin—a geologic bowl-like structure filled with layered sedimentary rocks dating as far back as the Paleozoic age. The basin, which is nationally important for the production of energy resources, spans Montana, North Dakota, and South Dakota in the United States, and Manitoba and Saskatchewan in Canada. The three uppermost principal aquifer systems are the glacial, lower Tertiary, and Upper Cretaceous aquifer systems. As deep as 3,000 feet (ft) at the center of the basin, these are the most accessible aquifer systems in the basin and are the primary sources of potable groundwater in much of this area. The glacial aquifer system consists of Quaternary-age unconsolidated till, silt, clay, outwash sand and gravel, and occasional cobbles and boulders. The lower Tertiary and Upper Cretaceous aquifer systems consist primarily of sandstone, siltstone, mudstone, shale, and coal.

As energy demands have increased in the basin, horizontal drilling and hydraulic-fracturing have been used (especially since 2005) to develop previously inaccessible formations—namely, the Bakken and Three Forks Formations. The basin has yielded a large supply of domestic oil and natural gas since the 1950s, but the technologies required to extract those materials use large amounts of freshwater. The increasing freshwater demands of energy production in the Williston Basin, in addition to population growth, have led to a need for new tools to assess groundwater resources.

Groundwater salinity mapping using geophysical log analysis within the Fruitvale and Rosedale Ranch oil fields, Kern County, California, USA

Released September 26, 2018 15:15 EST

2018, Hydrogeology Journal

Michael J. Stephens, David H. Shimabukuro, Janice M. Gillespie, Will Chang

A method is presented for deriving a volume model of groundwater total dissolved solids (TDS) from borehole geophysical and aqueous geochemical measurements. While previous TDS mapping techniques have proved useful in the hydrogeologic setting in which they were developed, they may yield poor results in settings with lithological heterogeneity, complex water chemistry, or limited data. Problems arise because of assumed values for empirical constants in Archie’s Equation, unrealistic porosity and temperature gradients, or bicarbonate-rich groundwater. These issues become critical in complex geologic settings such as the San Joaquin Valley of California, USA. To address this, a method to map TDS in three dimensions is applied to the Fruitvale and Rosedale Ranch oil fields near Bakersfield, California. Borehole resistivity, porosity, and temperature data are used to derive TDS using Archie’s Equation, and are then kriged to interpolate TDS. Archie’s a and m (tortuosity factor and cementation exponent, respectively) are found by comparing model predictions, after kriging, to TDS measurements, and minimizing the differences via mathematical optimization. Contributions of abundant bicarbonate ions to TDS were corrected using an empirical model. This work was motivated by federal and state law requirements to monitor and protect underground sources of drinking water. Modeling shows the legally significant boundary of 10,000 ppm TDS is at ~1,067 m below sea level in Rosedale Ranch, and deepens into Fruitvale to ~1,341 m. Mapping groundwater TDS at this resolution reveals that TDS is primarily controlled by depth, recharge, stratigraphy, and in some places, by faulting and facies changes.

A values-based private landowner typology to improve grassland conservation initiatives

Released September 26, 2018 12:36 EST

2018, Society and Natural Resources

Lily A. Sweikert, Larry M. Gigliotti

Many conservation initiatives are based on natural science alone, despite an extensive body of literature demonstrating that the incorporation of social science generates more successful and lasting outcomes. The Land Use Value (LUV) scale is an example of a social science tool that grassland conservation practitioners can use to improve their understanding of the land use decisions of private agricultural landowners. Drawing on data from a mail survey, we demonstrated the utility of the LUV scale to segment agricultural producers by four LUV types (Humans First, Nature First, Interconnected, and Disconnected) with significantly different motivations and land use behaviors. This information can be used to evaluate and align grassland conservation practices, policies, and messaging with the LUV types of private agricultural landowners. Tools like the LUV scale are critical to building the social science capacity of conservation professionals and organizations, in order to improve the efficacy of conservation initiatives.

Variation in the vital rates of an Antarctic marine predator: the role of individual heterogeneity

Released September 26, 2018 12:31 EST

2018, Ecology (99) 2385-2396

J. Terrill Paterson, Jay J. Rotella, William A. Link, Robert A. Garrott

Variation in life‐history traits such as lifespan and lifetime reproductive output is thought to arise, in part, due to among‐individual differences in the underlying probabilities of survival and reproduction. However, the stochastic nature of demographic processes can also generate considerable variation in fitness‐related traits among otherwise‐identical individuals. An improved understanding of life‐history evolution and population dynamics therefore depends on evaluating the relative role of each of these processes. Here, we used a 33‐yr data set with reproductive histories for 1,274 female Weddell seals from Erebus Bay, Antarctica, to assess the strength of evidence for among‐individual heterogeneity in the probabilities of survival and reproduction, while accounting for multiple other sources of variation in vital rates. Our analysis used recent advances in Bayesian model selection techniques and diagnostics to directly compare model fit and predictive power between models that included individual effects on survival and reproduction to those that did not. We found strong evidence for costs of reproduction to both survival and future reproduction, with breeders having rates of survival and subsequent reproduction that were 3% and 6% lower than rates for non‐breeders. We detected age‐related changes in the rates of survival and reproduction, but the patterns differed for the two rates. Survival rates steadily declined from 0.92 at age 7 to 0.56 at the maximal age of 31 yr. In contrast, reproductive rates increased from 0.68 at age 7 to 0.79 at age 16 and then steadily declined to 0.37 for the oldest females. Models that included individual effects explained more variation in observed life histories and had better estimated predictive power than those that did not, indicating their importance in understanding sources of variation among individuals in life‐history traits. We found that among‐individual heterogeneity in survival was small relative to that for reproduction. Our study, which found patterns of variation in vital rates that are consistent with a series of predictions from life‐history theory, is the first to provide a thorough assessment of variation in important vital rates for a long‐lived, high‐latitude marine mammal while taking full advantage of recent developments in model evaluation.

Deciphering the dynamics of inorganic carbon export from intertidal salt marshes using high-frequency measurements

Released September 26, 2018 12:23 EST

2018, Marine Chemistry

Sophie N. Chu, Zhaohui Aleck Wang, Meagan Gonneea, Kevin D. Kroeger, Neil Kamal Ganju

The lateral export of carbon from coastal marshes via tidal exchange is a key component of the marsh carbon budget and coastal carbon cycles. However, the magnitude of this export has been difficult to accurately quantify due to complex tidal dynamics and seasonal cycling of carbon. In this study, we use in situ, high-frequency measurements of dissolved inorganic carbon (DIC) and water fluxes to estimate lateral DIC fluxes from a U.S. northeastern salt marsh. DIC was measured by a CHANnelized Optical Sensor (CHANOS) that provided an in situ concentration measurement at 15-min intervals, during periods in summer (July – August) and late fall (December). Seasonal changes in the marsh had strong effects on DIC concentrations, while tidally-driven water fluxes were the fundamental vehicle of marsh carbon export. Episodic events, such as groundwater discharge and mean sea water level changes, can impact DIC flux through altered DIC concentrations and water flow. Variability between individual tides within each season was comparable to mean variability between the two seasons. Estimated mean DIC fluxes based on a multiple linear regression (MLR) model of DIC concentrations and high-frequency water fluxes agreed reasonably well with those derived from CHANOS DIC measurements for both study periods, indicating that high-frequency, modeled DIC concentrations, coupled with continuous water flux measurements and a hydrodynamic model, provide a robust estimate of DIC flux. Additionally, an analysis of sampling strategies revealed that DIC fluxes calculated using conventional sampling frequencies (hourly to two-hourly) of a single tidal cycle are unlikely to capture a representative mean DIC flux compared to longer-term measurements across multiple tidal cycles with sampling frequency on the order of tens of minutes. This results from a disproportionately large amount of the net DIC flux occurring over a small number of tidal cycles, while most tides have a near-zero DIC export. Thus, high-frequency measurements (on the order of tens of minutes or better) over the time period of interest are necessary to accurately quantify tidal exports of carbon species from salt marshes.

Drivers of chaparral type conversion to herbaceous vegetation in coastal Southern California

Released September 26, 2018 12:09 EST

2018, Diversity and Distributions

Alexandra D. Syphard, Teresa J. Brennan, Jon E. Keeley


In Southern California, native woody shrublands known as chaparral support exceptional biodiversity. However, large‐scale conversion of chaparral into largely exotic herbaceous cover is a major ecological threat and serious conservation concern. Due to substantial uncertainty regarding the causes and extent of this vegetation change, we aimed to quantify the primary drivers of and map potentially vulnerable locations for vegetation type conversion from woody into herbaceous cover.


Santa Monica Mountains National Recreational Area, Southern California, USA.


We used air photograph image interpretation to quantify the extent to which chaparral shrublands transitioned to herbaceous cover from 1943 to 2014 across nearly 800 randomly located plots. Comparing plots that remained chaparral to those that converted to herbaceous cover, we performed hierarchical partitioning to quantify the independent contribution of a range of explanatory variables, and then used classification trees to explore variable interactions. We also developed a spatial model to create a seamless map delineating relative probability of type conversion.


Of the original plots that were chaparral in 1943, 284 (36%) changed cover by 2014, with 79 completely converting, and 142 mostly converting to herbaceous cover. The primary mechanism behind shrubland decline and replacement was short intervals between fires (<=10 years), and type conversion was most likely to occur in arid parts of the landscape with low topographic heterogeneity and close proximity to trails and roads. Predictive maps delineated several hotspots with environmental conditions similar to those of type‐converted plots.

Main conclusions

Chaparral type conversion is a widespread conservation concern, and results here suggest that short‐interval fire and landscape disturbance are the most likely factors to exacerbate it, particularly in water‐limited portions of the landscape where chaparral is subject to greater physiological stress and slower recovery. Reducing fire ignitions and mapping vulnerable areas may be important strategies for prevention.

Carbon storage potential in a recently created brackish marsh in eastern North Carolina, USA

Released September 26, 2018 12:07 EST

2018, Ecological Engineering

Yo-Jin Shiau, Michael R. Burchell, Ken W. Krauss, Stephen W. Broome, Francois Birgand

Carbon (C) sequestration through accumulated plant biomass and storage in soils can potentially make wetland ecosystems net C sinks. Here, we collected GHG flux, plant biomass, and litter decomposition data from three distinct vegetation zones (SpartinaalternifloraJuncus roemerianus and Spartina patens) on a 7-year-old created brackish marsh in North Carolina, USA, and integrate these data into an overall C mass balance budget. The marsh fixed an average of 1.85 g C m−2 day−1 through plant photosynthesis. About 41–46% of the fixed C remained in plants, while 18.4% of the C was decomposed and released back to the atmosphere as CO2 and CH4, and 8.6–13.2% of the decomposed C was stored as soil C. In all, this created marsh sequestered 28.7–44.7 Mg CO2 year−1 across the 14 ha marsh. Because the brackish marsh emitted only small amounts of CH4 and N2O, the CO2 equivalent emission of the marsh was −0.87 to −0.56 g CO2-eq m−2 day−1, indicating the marsh has a net effect in reducing GHGs to the atmosphere and contributes to cooling. However, resultant CO2 credit (through the increment of soil C) would be worth only $30.76–$47.90 USD per hectare annually, or $431–$671 per year for the project, which, coupled with other enhanced ecosystem services, could provide landowners with some additional economic incentive for future creation projects. Nevertheless, C mass balance determinations and radiative cooling metrics showed promise in demonstrating the potential of a young created brackish marsh to act as a net carbon sink.

A causal partition of trait correlations: using graphical models to derive statistical models from theoretical language

Released September 26, 2018 11:05 EST

2018, Ecosphere (9) 1-15

James P. Cronin, Donald Schoolmaster

Recent studies hypothesize various causes of species‐level trait covariation, namely size (e.g., metabolic theory of ecology and leaf economics spectrum), pace‐of‐life (e.g., slow‐to‐fast continuum; lifestyle continuum), evolutionary history (e.g., phylogenetic conservatism), and ecological conditions (e.g., stabilizing selection). Various methods have been used in attempts to partition trait correlation among these influences (e.g., univariate analysis, principal components analysis, and factor analysis). However, it is not clear that the implied causal structure assumed by these methods matches the hypothesized causal structure driving trait correlations, a situation that can potentially lead to biased estimates and incorrect partitioning among mechanisms. Here, we propose the application of graphical causal models (GCM) for across‐kingdom synthesis and to aid researchers in their selection of correct analytical strategies. Graphical causal models use causal diagrams (i.e., box‐and‐arrow graphs) to represent expert knowledge of the data‐generating processes to analytically investigate the possibility of identifying hypothesized causal associations. We developed a causal diagram that synthesizes prominent hypotheses of trait covariation. Using the causal diagram, we (1) derived a quantitative expression to partition trait covariance among its hypothesized causal elements (i.e., size, pace‐of‐life, evolutionary history, and ecological conditions) and (2) developed analytic strategies to attribute trait covariance among the hypothesized causal elements under real‐world data availability, namely unobserved variables (i.e., pace‐of‐life) and confounding variables (i.e., evolutionary history and ecological conditions). Finally, we tested each analytic strategy by simulating trait datasets and, after incorporating the data limitations, tested their ability to correctly partition trait covariance. The analytical strategies were able to correctly partition trait covariance into the hypothesized causal elements of size, pace‐of‐life, and the historical effects of evolutionary history and ecological conditions. We demonstrate the efficacy of these strategies by applying them to a widely used trait dataset. Overall, the application of GCM revealed that researchers have used inappropriate measures to represent their theoretical constructs and have relied on analytical strategies that violated their causal assumptions, likely resulting in biased estimates. We discuss how this mismatch between theoretical language and statistical methods is prevalent in species‐level, trait‐based research and call for future studies to address these limitations.

Sediment Source Assessment Using Sediment Fingerprints

Released September 26, 2018 09:30 EST

2018, Fact Sheet 2018-3008

Allen C. Gellis, Lillian E. Gorman Sanisaca, Matthew J. Cashman


Sediment is one of the most common causes of loss of stream-biologic integrity, whether in suspension in the water column, or as deposition on a stream or lake bottom. Fine-grained silts and clays are of particular concern because they can degrade habitat and often carry phosphorus and (or) other contaminants harmful to humans and aquatic life. Sediment-impaired water bodies, usually identified by fair to poor macroinvertebrate index scores, are placed on the 303(d) list of impaired waters, where a sediment Total Maximum Daily Load (TMDL) is developed under the Clean Water Act (https://www.epa.gov/tmdl). In order to effectively manage sediment, it is necessary to identify the sediment sources and locations of “hot spots” of erosion and deposition.

Frequency of volcanic eruptions in the Mammoth Lakes Sierra

Released September 26, 2018 08:53 EST

2018, Fact Sheet 2018-3059

Wes Hildreth, Andrew T. Calvert, Judith Fierstein, Mae Marcaida

Geologists recognize lavas and ash deposits from about 60 past eruptions in the area around Mammoth Mountain and Devils Postpile, California. This raises the unanswerable question, “When will it erupt again?” An alternative, answerable, and informative question is, “How often has it erupted?”

In the Mammoth Lakes Sierra, geologists have mapped in great detail all the lavas and ash deposits produced by those 60 eruptions. They have dated almost all of them by laboratory methods, showing that eruptions have been repetitive and persistent, though not quite regular, over the last quarter-million years. For few volcanoes in the world is the long-term eruptive frequency so well calibrated as in the Mammoth Lakes Sierra.

Plant production responses to precipitation differ along an elevation gradient and are enhanced under extremes

Released September 25, 2018 16:30 EST

2018, Ecosystems

Seth M. Munson, Erin L. Bunting, John B. Bradford, Bradley J. Butterfield, Jennifer R. Gremer

The sensitivity of plant production to precipitation underlies the functioning of ecosystems. Studies that relate long-term mean annual precipitation and production across multiple sites(spatial relationship) or examine interannual linkages within a site (temporal relationship) can reveal biophysical controls over ecosystem function but have limited ability to infer responses to extreme changes in precipitation that may become more common under climate change. To overcome limitations of using a single approach, we integrated satellite- and ground-based estimates of production with a standardized, multi-site precipitation manipulation experiment across a grassland elevation gradient in the southwestern USA. The responsiveness of production to changes in precipitation followed the order: temporal (0.06–0.13 g m−2 mm−1) < spatial (0.21 g m−2 mm−1) < experimental relationship (0.25–0.42 g m−2 mm−1), suggesting that spatial and temporal relationships determined with satellite- and ground-based estimates cannot be extrapolated to determine the effect of extreme events. A strong production response to differences in mean annual precipitation across sites reinforces a regional control of water availability. Interannual sensitivity to precipitation was strongest at the low elevation grasslands, and the high elevation mixed conifer meadow had a large reduction in production in a drought year. Extreme experimental drought strongly reduced production in low elevation grasslands, but water addition had mixed effects. High elevation meadows were insensitive to both extreme drought and water addition. Our results highlight the importance of accounting for extreme climate regimes and site-level factors when scaling climate change effects up to regional and global scales.

Burn severity controls on postfire Araucaria‐Nothofagus regeneration in the Andean Cordillera

Released September 25, 2018 16:29 EST

2018, Journal of Biogeography

Timothy J. Assal, Mauro E. Gonzalez, Jason S. Sibold


The aim of the study was to investigate postfire regeneration patterns of Araucaria‐Nothofagus forests on the west slope of the Andes; to evaluate the relationship between remotely sensed burn severity and forest mortality; and to assess controls of burn severity on forest response at local spatio‐temporal scales.


Araucanía region in the western Andean Range of south‐central Chile where fire occurred during the 2001–2002 season.


Sampling of prefire stand structure and postfire vegetation response was performed along a burn severity gradient a decade after the fire. We evaluated the relationship between field‐measured tree mortality and satellite‐derived burn severity using a generalized linear model. We fit zero‐inflated mixture models to regeneration data of each genus to assess the importance of abiotic variables, stand characteristics, and biotic interactions.


The relative version of the delta Normalized Burn Ratio explained 85% of the variability in canopy mortality. Nearly 12,000 hectares burned; the majority at high severity (67%). Regeneration densities of both genera were lower at higher levels of burn severity and higher with greater total basal area (live, dead, and down trees). The relative effect size of burn severity on regeneration was nearly twice as large for Nothofagus, which suggests information legacies of Araucaria have cascading effects on postdisturbance material legacies.

Main conclusions

Araucaria‐Nothofagus mortality from wildfire can be readily mapped using satellite‐derived burn severity. Although environmental site characteristics and biotic interactions mediate regeneration, basal area, and burn severity are the main mechanisms controlling regeneration. Forest refugia and postfire regeneration are vulnerable to recurrent fire. Therefore, we expect future fire (either increased severity or frequency), driven by landscape level changes, as a potential mechanism that can reduce local resilience of these forests as initial postfire material legacies (e.g., refugia and regeneration) are removed from the landscape. Our findings highlight an approach to quantify important attributes of forest disturbance and refugia, and identify areas for monitoring postdisturbance regeneration as the forests throughout south‐central Chile and Argentina face a multitude of potential change agents.

Interpretation of low‐temperature thermochronometer ages from tilted normal fault blocks

Released September 25, 2018 16:24 EST

2018, Tectonics

Samuel A. Johnstone, Joseph P. Colgan

Low‐temperature thermochronometry is widely used to measure the timing and rate of slip on normal faults. Rates are often derived from suites of footwall thermochronometer samples, but regression of age vs. structural depth fails to account for the trajectories of samples during fault slip. We demonstrate that in rotating fault blocks, regression of age‐depth data is susceptible to significant errors (>10%) in the identification of the initiation and rate of faulting. Advection of heat and topographic growth influence the thermal histories of exhumed particles, but for a range of geologically reasonable fault geometries and rates these effects produce Apatite (U‐Th)/He ages comparable to those derived from rotation through fixed isotherms. We apply the fixed‐isotherm model to published data from the Pine Forest Range and the East Range, Nevada, by incorporating field and thermochronologic constraints into a Markov chain Monte Carlo model. Modeled parameters for the Pine Forest Range are described by narrow ranges of geologically reasonable values. Compared to slip rates of 0.3‐0.8 km/Myr and an inititation of faulting ca. 11‐12 Ma derived from visual inspection, the model predicts an average slip rate of ~1.1 km/Myr and an onset of faulting ca. 9‐10 Ma. For the East Range fault block the model suggests faulting begain ~17 Ma with an extension rate of ~3 km/Myr and slowed to an extension rate of ~0.5 km/Myr at ~14 Ma. The absence of a preserved partial retention zone in the East Range sample set limits how well the model can predict fault block geometry.

2018 report on incorporating sedimentary basin response into the design of tall buildings in Seattle, Washington

Released September 25, 2018 09:22 EST

2018, Open-File Report 2018-1149

Erin A. Wirth, Susan W. Chang, Arthur Frankel

On March 22, 2018, the Seattle Department of Construction and Inspections (SDCI) and the U.S. Geological Survey (USGS) convened a workshop of engineers and seismologists to provide guidance on incorporating sedimentary basin response into the design of tall buildings in Seattle. This workshop provided recommendations that build on those from a March 2013 workshop (Chang and others, 2014), primarily based on new results from 3-D simulations of magnitude (M) 9 Cascadia earthquakes (The M9 Project). Susan Chang, a geotechnical engineer with the Seattle Department of Construction and Inspections, organized and led the workshop; Art Frankel (USGS) assisted in constructing the agenda.

The workshop agenda and attendees are provided in the appendix. The attendees represented a wide range of expertise, including seismologists with expertise in ground motions and basin response, geotechnical engineers, and structural engineers. Their professional experience included working on local projects related to the design of long-period structures; peer reviewing ground motions for performance-based design of high-rises in Seattle; researching basin response in academic, government and industry settings; developing ground motion models; and representing local and national structural engineering organizations. In this report, we summarize the technical presentations, key discussion points, and recommendations from the workshop.

Flood-inundation maps for the lower Pawcatuck River in Westerly, Rhode Island, and Stonington and North Stonington, Connecticut

Released September 24, 2018 15:15 EST

2018, Scientific Investigations Report 2018-5112

Gardner C. Bent, Pamela J. Lombard

A series of 11 digital flood-inundation maps was developed for a 5.5-mile reach of the lower Pawcatuck River in Westerly, Rhode Island, and Stonington and North Stonington, Connecticut, by the U.S. Geological Survey (USGS) in cooperation with the Town of Westerly, Rhode Island, and the Rhode Island Office of Housing and Community Development. The coverage of the maps extends from downstream from the Ashaway River inflow at the State Border between Hopkinton and Westerly, Rhode Island, and North Stonington, Connecticut, to about 500 feet (ft) downstream from the U.S. Route 1/Broad Street bridge on the State border between Westerly, Rhode Island, and Stonington, Connecticut. A one-dimensional step-backwater hydraulic model created and calibrated for an ongoing (2018) Federal Emergency Management Agency Flood-Insurance Study for New London County, Connecticut and Washington County, Rhode Island was updated for this study. The hydraulic model reflects the removal of the White Rock dam during 2015–16, and was calibrated using the stage-discharge relation at the USGS Pawcatuck River at Westerly, Rhode Island, streamgage (01118500) and documented high-water marks from the March 30, 2010, flood, which had a peak flow slightly greater than the estimated 0.2-percent annual exceedance probability floodflow.

The hydraulic model was used to compute water-surface profiles for 11 flood stages at 1-ft intervals referenced to the USGS Pawcatuck River at Westerly, Rhode Island, streamgage (01118500) and ranging from 6.0 ft (3.32 ft, North American Vertical Datum of 1988), which is the National Weather Service Advanced Hydrologic Prediction Service flood category “action stage,” to 16.0 ft (13.32 ft, North American Vertical Datum of 1988), which is the maximum stage of the stage-discharge relation at the streamgage and exceeds the National Weather Service Advanced Hydrologic Prediction Service flood category “major flood stage” of 11.0 ft. The simulated water-surface profiles were combined with a geographic information system digital elevation model derived from light detection and ranging (lidar) data with a 1.0-ft vertical accuracy to create flood-inundation maps. The flood-inundation maps depict estimates of the areal extent and depth of flooding corresponding to 11 selected flood stages at the streamgage. The flood-inundation maps depict only riverine flooding and do not depict any tidal backwater or coastal storm surge that could occur in the lower part of the river reach. The flood-inundation maps can be accessed through the USGS Flood Inundation Mapping Science website at https://water.usgs.gov/osw/flood_inundation. Near-real-time stages and discharges at the Pawcatuck River streamgage can be obtained from the USGS National Water Information System at https://waterdata.usgs.gov/. The National Weather Service Advanced Hydrologic Prediction Service provides flood forecast of stage for this site (WSTR1) at https://water.weather.gov/ahps/.

The availability of flood-inundation maps referenced to current and forecasted water levels at the USGS Pawcatuck River at Westerly, Rhode Island streamgage (01118500) can provide emergency management personnel and residents with information that is critical for flood response activities such as evacuations and road closures, and postflood recovery efforts. The flood-inundation maps are nonregulatory but provide Federal, State, and local agencies and the public with estimates of the potential extent of flooding during flood events.

Comparing public-supply and shallow aquifer groundwater quality in the North San Francisco Bay Aquifers, California

Released September 24, 2018 14:05 EST

2018, Fact Sheet 2018-3064

George L. Bennett

Groundwater quality in the North San Francisco Bay area Public-Supply and Shallow Aquifer Systems was investigated by the GAMA-PBP. The North San Francisco Bay Public-Supply Aquifer System study unit (NSF-PA) was sampled in 2004. The North San Francisco Bay Shallow Aquifer System study unit (NSF-SA) was sampled in 2012. The NSF-PA and NSF-SA largely coincide areally; however, they represent different parts of the aquifer system vertically. The NSF-PA examined deeper groundwater primarily used for public supply, whereas the NSF-SA examined relatively shallow groundwater primarily used for domestic supply. Both study units were divided into two study areas: (1) alluvium-filled groundwater basins called the Valleys and Plains study area and (2) volcanic, metamorphic, and ultramafic hard-rock highlands surrounding the Valleys and Plains called the Highlands study area.

Earth as art 5

Released September 24, 2018 13:26 EST

2018, General Information Product 186

U.S. Geological Survey

Fanciful Fluorescence. Lurking Madness. Serene Expressions.

The titles of the images in this fifth edition of Earth As Art speak to the powerfully artistic qualities of Earth’s natural features when tinged with unnatural colors.

Art serves as a great partner in the communication of science, bringing emotion to the pursuit of understanding. The pieces in this collection look like abstract art but are actual satellite images.

Satellite imagery has long served the rational and disciplined approaches of science to better understand our Earth. But these images can also, with a bit of creativity, excite our imaginations with the beauty and art that surround us.

In this newest collection of Earth As Art, we continue to display the Earth as our eyes cannot see it—in creative combinations of visible and infrared light. Although beauty in art is often subjective, the science data provide objective views of the Earth’s changing land surface. However, we will let these images speak to you as art. Enjoy the latest additions to Earth As Art!

The images in the Earth As Art 5 collection can be downloaded for free from the Earth Resources Observation and Science (EROS) Center Image Gallery at https://eros.usgs.gov/image-gallery/earth-art-5.

Using mercury injection pressure analyses to estimate sealing capacity of the Tuscaloosa marine shale in Mississippi, USA: Implications for carbon dioxide sequestration

Released September 24, 2018 13:26 EST

2018, International Journal of Greenhouse Gas Control (78) 375-387

Celeste D. Lohr, Paul C. Hackley

This work used mercury injection capillary pressure (MICP) analyses of the Tuscaloosa Group in Mississippi, including the Tuscaloosa marine shale (TMS), to assess their efficacy and sealing capacity for geologic carbon dioxide (CO2) sequestration. Tuscaloosa Group porosity and permeability from MICP were evaluated to calculate CO2 column height retention. TMS and Lower Tuscaloosa shale samples have, respectively, Swanson permeability values less than 0.003 md and 0.00245 md; porosity from 3.86% to 9.86% and 1.34% to 7.96%; median pore throat sizes from 0.00342 to 0.0111 μm and 0.00311 to 0.017 μm; and pore radii from 0.0130 to 0.152 μm and 0.0132 to 0.149 μm. Mercury entry pressures for the TMS and Lower Tuscaloosa range from 4.9 to 57.1 MPa and 5.0 to 56.3 MPa, respectively. Calculated CO2 column heights that the TMS sample set can retain in the reservoir range from 23 to 255 m when the TMS is near 100% water saturation. Potential top seal leakage is more likely to be influenced by the numerous well penetrations through the confining system of the TMS rather than capillary failure. Results of this study demonstrate desirable sealing capacity of the TMS for geologic CO2 sequestration in reservoir sandstones of the Lower Tuscaloosa and could provide an analogue to other potential COsequestration top seals.

Mangrove forests in a rapidly changing world: Global change impacts and conservation opportunities along the Gulf of Mexico coast

Released September 24, 2018 11:36 EST

2018, Estuarine, Coastal and Shelf Science (214) 120-140

Michael J. Osland, Laura C. Feher, Jorge López-Portillo, Richard H. Day, Daniel O. Suman, Jose Manuel Guzmán Menéndez, Victor H. Rivera-Monroy

Mangrove forests are highly-productive intertidal wetlands that support many ecosystem goods and services. In addition to providing fish and wildlife habitat, mangrove forests improve water quality, provide seafood, reduce coastal erosion, supply forest products, support coastal food webs, minimize flooding impacts, and support high rates of carbon sequestration. Despite their tremendous societal value, mangrove forests are threatened by many aspects of global change. Here, we examine the effects of global change on mangrove forests along the Gulf of Mexico coast, which is a valuable region for advancing understanding of global change impacts because the region spans multiple ecologically-relevant abiotic gradients that are representative of other mangrove transition zones across the world. We consider the historical and anticipated future responses of mangrove forests to the following aspects of global change: temperature change, precipitation change, accelerated sea-level rise, tropical cyclone intensification, elevated atmospheric carbon dioxide, eutrophication, invasive non-native species, and land use change. For each global change factor, we provide an initial global perspective but focus primarily on the three countries that border the Gulf of Mexico: United States, Mexico, and Cuba. The interactive effects of global change can have large ecological consequences, and we provide examples that highlight their importance. While some interactions between global change drivers can lead to mangrove mortality and loss, others can lead to mangrove expansion at the expense of other ecosystems. Finally, we discuss strategies for using restoration and conservation to maximize the adaptive capacity of mangrove forests to global change. To ensure that the ecosystem goods and services provided by mangrove forests continue to be available for future generations, there is a pressing need to better protect, manage, and restore mangrove forests as well as the adjacent ecosystems that provide opportunities for adaptation in response to global change.

Serum proteins in healthy and diseased Florida manatees (Trichechus manatus latirostris)

Released September 24, 2018 11:31 EST

2018, Comparative Clinical Pathology

John W. Harvey, Kendall E. Harr, David Murphy, Michael T. Walsh, Martina deWit, Charles J. Deutsch, Robert K. Bonde

A major goal of this study was to determine whether serum protein fractions of healthy Florida manatees differ with age, sex, or living environments (wild versus housed). A second goal was to determine which serum protein fractions vary in diseased versus healthy manatees. Serum protein fractions were determined using agarose gel electrophoresis. Healthy adults had slightly higher total serum protein and total globulin concentrations than younger animals. This largely resulted from an increase in gamma globulins with age. Total serum protein, albumin, alpha-1 globulin, beta globulin, and total globulin concentrations were slightly higher in housed manatees compared to wild manatees, but there was no significant difference in the albumin/globulin (A/G) ratio, suggesting a difference in hydration between these groups. No significant differences were attributable to sex or pregnancy. Serum albumin concentrations and A/G ratios were significantly lower for manatees with boat trauma, entanglements, emaciation, or cold stress compared to healthy manatees. Variable increases were seen in alpha-1globulins, alpha-2 globulins, beta globulins, and gamma globulins. These globulin fractions contain positive acute-phase proteins and immunoglobulins, and their increases may reflect acute or chronic active inflammation. Changes in serum protein fractions were not consistent enough to justify the use of serum protein electrophoresis as a routine diagnostic test for manatees. However, serum (or plasma) protein electrophoresis is required when accurate values for albumin and globulins are needed in manatees and in determining which protein fractions may account for a hyperproteinemia or hypoproteinemia reported in a clinical chemistry panel.

Genetic analyses of Astragalus sect. Humillimi (Fabaceae) resolve taxonomy and enable effective conservation

Released September 24, 2018 11:28 EST

2018, American Journal of Botany

Robert Massatti, Matthew Belus, Shahed Dowlatshahi, Gerard J. Allan

Premise of the Study

Astragalus sect. Humillimi is distributed across the southwestern United States and contains two endangered taxa, A. cremnophylax var. cremnophylax and A. humillimus. The former was originally described from the South Rim of the Grand Canyon. Analysis of individuals discovered on the North Rim of the Grand Canyon yielded some evidence that the population represented a distinct species. To enable effective conservation, we clarify the group's taxonomy and characterize the genetic diversity of A. cremnophylax and A. humillimus.


We used AFLPs to genotype most species in sect. Humillimi, focusing on the two endangered forms. We examined patterns of genetic diversity using complementary analytical approaches.

Key Results

Our results demonstrate that North Rim populations group with A. c. var. cremnophylax. We found low levels of genetic diversity at certain localities and strong differentiation among populations. Astragalus humillimus, which has suffered recent and severe population declines, exhibits weak differentiation among and low diversity within populations.


Our results clarify the taxonomy of sect. Humillimi and define the boundaries of A. c. var. cremnophylax, which is shown to inhabit both rims of the Grand Canyon. This clarification, and detailed analysis of genetic variation within both endangered taxa, may advance ongoing efforts to conserve these taxa. Our results suggest that range‐wide genetic analysis of A. humillimus may inform recovery strategies for this taxon.

Quantifying and forecasting changes in the areal extent of river valley sediment in response to altered hydrology and land cover

Released September 24, 2018 10:49 EST

2018, Progress in Physical Geography: Earth and Environment

Alan Kasprak, Joel B. Sankey, Daniel Buscombe, Joshua Caster, Amy East, Paul E. Grams

In river valleys, sediment moves between active river channels, near-channel deposits including bars and floodplains, and upland environments such as terraces and aeolian dunefields. Sediment availability is a prerequisite for the sustained transfer of material between these areas, and for the eco-geomorphic functioning of river networks in general. However, the difficulty of monitoring sediment availability and movement at the reach or corridor scale has hindered our ability to quantify and forecast the response of sediment transfer to hydrologic or land cover alterations. Here we leverage spatiotemporally extensive datasets quantifying sediment areal coverage along a 28 km reach of the Colorado River in Grand Canyon, southwestern USA. In concert with information on hydrologic alteration and vegetation encroachment resulting from the operation of Glen Canyon Dam (constructed in 1963) upstream of our study reach, we model the relative and combined influence of changes in (a) flow and (b) riparian vegetation extent on the areal extent of sediment available for transport in the river valley over the period from 1921 to 2016. In addition, we use projections of future streamflow and vegetation encroachment to forecast sediment availability over the 20 year period from 2016 to 2036. We find that hydrologic alteration has reduced the areal extent of bare sediment by 9% from the pre- to post-dam periods, whereas vegetation encroachment further reduced bare sediment extent by 45%. Over the next 20 years, the extent of bare sediment is forecast to be reduced by an additional 12%. Our results demonstrate the impact of river regulation, specifically the loss of annual low flows and associated vegetation encroachment, on reducing the sediment available for transfer within river valleys. This work provides an extendable framework for using high-resolution data on streamflow and land cover to assess and forecast the impact of watershed perturbation (e.g. river regulation, land cover shifts, climate change) on sediment connectivity at the corridor scale.

Water use in Washington, 2015

Released September 24, 2018 08:50 EST

2018, Fact Sheet 2018-3058

Elisabeth T. Fasser


Water use in the State of Washington has evolved during the past century from small withdrawals used for domestic and stock needs to the diverse needs of current public supply systems, domestic water users, irrigation projects, industrial plants, and aquaculture industries. Increasing demand for water makes the accountability of water use an important issue.

A few State and local agencies in Washington collect water-use information for specific categories of water use; currently, only the U.S. Geological Survey (USGS) compiles cumulative water-use information across the State for a comprehensive range of uses.

Since 1950, on a 5-year cycle, the USGS has compiled and published estimates of water withdrawal and use for specific categories aggregated at the county, State, and national level. The information is shared publicly through the USGS Water Use in the United States website (https://water.usgs.gov/watuse/) and national publications that detail water use definitions, categories, trends, and data for every state. The data are compiled individually by each state from available sources, and are augmented by estimates from national models for categories that have limited data. The USGS Washington Water Science Center is responsible for compiling their estimates and maintains the State water use webpage (https://wa.water.usgs.gov/data/wuse/) of State-level information and links to the national program.

California sea otter (Enhydra lutris nereis) census results, spring 2018

Released September 24, 2018 07:04 EST

2018, Data Series 1097

Brian B. Hatfield, Julie L. Yee, Michael C. Kenner, Joseph A. Tomoleoni, M. Tim Tinker

The 2018 census of southern sea otters (Enhydra lutris nereis) was conducted from late April to mid-May along the mainland coast of central California and in April at San Nicolas Island in southern California. The 3-year average of combined counts from the mainland range and San Nicolas Island was 3,128, a decrease of 58 sea otters from the previous year. The 5-year average trend in abundance, including both the mainland range and San Nicolas Island populations, remains positive at 1.3 percent per year. Continuing lack of growth in the range peripheries likely explains the cessation of range expansion.

Assessing the impact of site-specific BMPs using a spatially explicit, field-scale SWAT model with edge-of-field and tile hydrology and water-quality data in the Eagle Creek watershed, Ohio

Released September 21, 2018 11:21 EST

2018, Water (10) 1-37

Katherine R. Merriman, Prasad Daggupati, Raghavan Srinivasan, Chad Toussant, Amy M. Russell, Brett A. Hayhurst

The Eagle Creek watershed, a small subbasin (125 km2) within the Maumee River Basin, Ohio, was selected as a part of the Great Lakes Restoration Initiative (GLRI) “Priority Watersheds” program to evaluate the effectiveness of agricultural Best Management Practices (BMPs) funded through GLRI at the field and watershed scales. The location and quantity of BMPs were obtained from the U.S. Department of Agriculture-Natural Resources Conservation Service National Conservation Planning (NCP) database. A Soil and Water Assessment Tool (SWAT) model was built and calibrated for this predominantly agricultural Eagle Creek watershed, incorporating NCP BMPs and monitoring data at the watershed outlet, an edge-of-field (EOF), and tile monitoring sites. Input air temperature modifications were required to induce simulated tile flow to match monitoring data. Calibration heavily incorporated tile monitoring data to correctly proportion surface and subsurface flow, but calibration statistics were unsatisfactory at the EOF and tile monitoring sites. At the watershed outlet, satisfactory to very good calibration statistics were achieved over a 2-year calibration period, and satisfactory statistics were found in the 2-year validation period. SWAT fixes parameters controlling nutrients primarily at the watershed level; a refinement of these parameters at a smaller-scale could improve field-level calibration. Field-scale modeling results indicate that filter strips (FS) are the most effective single BMPs at reducing dissolved reactive phosphorus, and FS typically decreased sediment and nutrient yields when added to any other BMP or BMP combination. Cover crops were the most effective single, in-field practice by reducing nutrient loads over winter months. Watershed-scale results indicate BMPs can reduce sediment and nutrients, but reductions due to NCP BMPs in the Eagle Creek watershed for all water-quality constituents were less than 10%. Hypothetical scenarios simulated with increased BMP acreages indicate larger investments of the appropriate BMP or BMP combination can decrease watershed level loads.

Using tectonic tremor to constrain seismic‐wave attenuation in Cascadia

Released September 20, 2018 15:52 EST

2018, Geophysical Research Letters

Geena F. Littel, Amanda M. Thomas, Annemarie S. Baltay

Tectonic tremor can be used to constrain seismic‐wave attenuation for use in ground‐motion prediction equations (GMPEs) in regions where moderately sized earthquakes occur infrequently. Here we quantify seismic‐wave attenuation by inverting tremor ground motion amplitudes in different frequency bands of interest, to determine frequency dependence of and spatial variations in seismic‐wave attenuation in Cascadia. Due to the density of tremor data, we are able to resolve along‐strike variations in the attenuation parameter. We find that tectonic tremor exhibits the frequency dependence expected for attenuation, as determined from GMPEs developed from moderate‐to‐large magnitude earthquakes. This implies that attenuation along these paths is independent of the source mechanism. This study demonstrates that tectonic tremor can be used to provide insight into the physical factors responsible for attenuation, and to refine estimates of attenuation for ground‐motion prediction, thus having important implications for hazard assessment and engineering seismology.

Compositional data analysis of coal combustion products with an application to a Wyoming power plant

Released September 20, 2018 15:40 EST

2018, Mathematical Geosciences (50) 639-657

J. A. Martín-Fernández, Ricardo A. Olea, Leslie F. Ruppert

A mathematically sound approach for summarizing chemical analyses of feed coal and all its combustion products (bottom ash, economizer fly ash, and fly ash) is presented. The nature of the data requires the application of compositional techniques when conducting statistical analysis, techniques that have not been applied before to the study of partitioning of elements between the coal that enters the boiler and the associated coal combustion products. A collection of descriptive and inferential compositional techniques was used to analyze the coal combustion products from a Wyoming power plant burning Paleocene Wyodak–Anderson coal. The significance of the fluctuation in ash composition is determined by using a Hotelling’s T-squared test and bootstrapping. Tree displays allow for visualization of the progressive effect of filters in removal of chemical species based on their geochemical composition. Results indicate that, in general, as the suspended combustion products entrained in the flue gases move closer to the stack, chemical species are removed from the combustion gas, starting with minerals associated with elements having the lowest volatility.

The ecology of movement and behaviour: a saturated tripartite network for describing animal contacts

Released September 20, 2018 15:35 EST

2018, Proceedings of the Royal Society B: Biological Sciences (285)

Kezia R. Manlove, Christina M. Aiello, Pratha Sah, Bree Cummins, Peter J. Hudson, Paul C. Cross

Ecologists regularly use animal contact networks to describe interactions underlying pathogen transmission, gene flow, and information transfer. However, empirical descriptions of contact often overlook some features of individual movement, and decisions about what kind of network to use in a particular setting are commonly ad hoc. Here, we relate individual movement trajectories to contact networks through a tripartite network model of individual, space, and time nodes. Most networks used in animal contact studies (e.g. individual association networks, home range overlap networks, and spatial networks) are simplifications of this tripartite model. The tripartite structure can incorporate a broad suite of alternative ecological metrics like home range sizes and patch occupancy patterns into inferences about contact network metrics such as modularity and degree distribution. We demonstrate the model's utility with two simulation studies using alternative forms of ecological data to constrain the tripartite network's structure and inform expectations about the harder-to-measure metrics related to contact.

Assessment of undiscovered oil and gas resources in the Akita Basin Province, Japan, 2018

Released September 20, 2018 12:48 EST

2018, Fact Sheet 2018-3047

Christopher J. Schenk, Tracey J. Mercier, Marilyn E. Tennyson, Cheryl A. Woodall, Thomas M. Finn, Phuong A. Le, Kristen R. Marra, Stephanie B. Gaswirth, Heidi M. Leathers-Miller, Ronald M. Drake II

Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 111 million barrels of oil and 85 billion cubic feet of gas in the Akita Basin Province of Japan.

Annual and approximately quarterly series peak streamflow derived from interpretations of indirect measurements for a crest-stage gage network in Texas through water year 2015

Released September 20, 2018 11:57 EST

2018, Scientific Investigations Report 2018-5107

William H. Asquith, Glenn R. Harwell, Karl E. Winters

In 2006, the U.S. Geological Survey (USGS), in
cooperation with the Texas Department of Transportation,
began collecting annual and approximately quarterly series
peak-streamflow data at streamflow-gaging stations in smallto
medium-sized watersheds in central and western Texas
as part of a crest-stage gage (CSG) network, along with
selected flood-hydrograph data at a subset of these stations.
CSGs record the peak stage during storm events, which is
the maximum gage height (elevation of water surface above
a local vertical datum), at each CSG station. Established and
widely used indirect methods of peak streamflow estimation
and interpretation, such as culvert-flow, slope-area, and
flow-over-road methods, are used in conjunction with peak
gage height data to create the database of peak streamflow
described herein. The CSG network is focused on hydrology
of small- to medium-sized watersheds in central and western
Texas because additional streamflow data for this semiarid
to arid study area will eventually provide for more statistical
information and presumably reduced uncertainty in regional
regression equations or other regionalized statistical methods
for peak-streamflow frequency estimation at ungaged
locations. The database of annual and approximately quarterly
peak streamflow is published through USGS ScienceBase and
described in this report.

Four-dimensional isotopic approach to identify perchlorate sources in groundwater: Application to the Rialto-Colton and Chino subbasins, southern California (USA)

Released September 20, 2018 10:56 EST

2018, Applied Geochemistry (97) 213-225

Paul B. Hatzinger, J.K. Böhlke, Neil C. Sturchio, John A. Izbicki, Nicholas F. Teague

Perchlorate (ClO4) in groundwater can be from synthetic or natural sources. Natural sources include ClO4 associated with historical application of imported natural nitrate fertilizer from the Atacama Desert of Chile, and indigenous ClO4 that accumulates locally in arid regions from atmospheric deposition. The Rialto-Colton groundwater subbasin, 80 km east of Los Angeles, California, includes two mapped ClO4 plumes from known military/industrial sources. Larger areas downgradient from those plumes, and in the Chino subbasin to the southwest, also contain ClO4. Perchlorate from wells was analyzed for chlorine and oxygen stable isotope ratios (δ37Cl, δ18O, Δ17O) and radioactive chlorine-36(36Cl) isotopic abundance, along with other geochemical, isotopic, and hydrogeologic data. Isotopic data show that synthetic ClO4 was the dominant source within the mapped plumes. Downgradient from the mapped plumes, and in the Chino subbasin, the dominant source of ClO4 was related to past agricultural use of Chilean (Atacama) nitrate fertilizer. The 36Cl and δ18O data indicate that wells having predominantly synthetic or Atacama ClO4 also contained small fractions of indigenous ClO4. Little or no differences were observed in isotopic composition or ClO4 source with depth in depth-dependent data from selected wells. Indigenous ClO4 was most evident in upgradient wells having ClO4 concentrations <1 μg/L, consistent with its occurrence as a background constituent throughout the region. Stable isotope ratios of chlorine and oxygen and 36Cl isotopic abundance data provided relatively unambiguous discrimination of synthetic and Atacama sources in most wells having ClO4 concentrations greater than 1 μg/L.

Geochemical conditions and nitrogen transport in nearshore groundwater and the subterranean estuary at a Cape Cod embayment, East Falmouth, Massachusetts, 2013–14

Released September 20, 2018 09:00 EST

2018, Scientific Investigations Report 2018-5095

John A. Colman, Denis R. LeBlanc, J.K. Böhlke, Timothy D. McCobb, Kevin D. Kroeger, Marcel Belaval, Thomas C. Cambareri, Gillian F. Pirolli, T. Wallace Brooks, Mary E. Garren, Tobias B. Stover, Ann Keeley

Nitrogen transport and transformation were studied during 2013 to 2014 by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, in a subterranean estuary beneath onshore locations on the Seacoast Shores peninsula, a residential area in Falmouth, Massachusetts, served by septic systems and cesspools, and adjacent offshore locations in the Eel River, a saltwater embayment connected to the ocean. The field investigation included installation and sampling of clusters of wells and temporary sampling points near a transect extending from about 35 meters (m) onshore to 18 m offshore.

The fresh groundwater at the study site formed a lens about 11 m thick at the shoreline that was underlain by saline groundwater. Groundwater flow in the water-table aquifer was oriented northwestward toward the embayment. Nitrate concentrations in the fresh groundwater at a site about 35 m onshore increased in the downward direction from less than 500 micromoles per liter near the water table to about 1,700 micromoles per liter just above the freshwater/saltwater transition zone. Dissolved oxygen was largely absent in the onshore fresh groundwater. Distributions of salinity, dissolved oxygen, and nitrate at the shoreline and offshore generally were similar to those onshore; at some locations, however, shallow saline water was present above the freshwater, and there were scattered occurrences of elevated dissolved oxygen concentrations.

Geochemical indicators of nitrate reduction, including concentrations of the reaction product nitrogen gas, stable isotope ratios of nitrate and nitrogen gas, and changes in alkalinity, provided evidence for nitrate reduction in two zones separated vertically by a zone 7–8 m thick with no evidence of nitrate reduction. The shallow nitrate-reduction zone was near the water table in fresh groundwater onshore, where nitrate reduction may be related to particular recharge conditions at nearby sources. The shallow nitrate-reduction zone also may be related to an interval of fine-grained sediments at about the same altitude (−1 to −6 m relative to the National Geodetic Vertical Datum of 1929), where flow is slower and reactive electron donors such as solid organic carbon, iron, or sulfide phases may be present to drive the reduction. The deep nitrate-reduction zone was near the freshwater/saltwater transition zone, where nitrate reduction may be related to mixing of freshwater containing nitrate and saltwater containing dissolved organic carbon and ammonium, or to fine-grained sediments near the transition zone. The maximum amount of nitrate converted to nitrogen gas was estimated to be less than or equal to 300 micromoles per liter in both nitrate-reduction zones.

The presence of nitrate and low dissolved oxygen concentrations in the 7–8-meter-thick zone between the shallow and deep nitrate-reduction zones are conditions that could permit nitrate reduction. The absence of evidence of nitrate reduction in the high-nitrate zone may have resulted from the lack of reactive electron donors in that depth interval. The high-nitrate zone dissipated somewhat in the offshore direction, but the current study did not extend far enough to encompass the fresh groundwater discharge area or determine how much of the nitrate was removed prior to discharge.

A shallow intertidal saltwater cell was formed during a spring tide by saltwater infiltration during tidal run-up on the beach. Nitrate reduction might have occurred if nitrate-containing fresh groundwater discharging to the estuary mixed with the saltwater containing dissolved organic carbon in this zone, but samples collected from the intertidal saltwater cell during this study were not analyzed for indicators of nitrate reduction.

Elevated dissolved oxygen concentrations in fresh groundwater 9 m offshore may indicate that groundwater flow was partly oblique to the sampling transect or that groundwater from a regional flow system was converging under the river near the study area. Flow directions also may have been affected by aquifer heterogeneity such as the shallow fine-grained sediments onshore and at the bottom of the Eel River. Improved understanding of the fate of nitrate in this type of complex setting might be gained by including additional characterization of aquifer heterogeneity and groundwater flow and extending investigations of nitrate reduction to the shallow sediments in the intertidal saltwater cell and adjacent subtidal zone and to locations farther offshore beneath the estuary.

Influence of permafrost distribution on groundwater flow in the context of climate-driven permafrost thaw: Example from Yukon Flats Basin, Alaska, United States

Released September 20, 2018 01:00 EST

2016, Water Resources Research (48)

Michelle Ann Walvoord, Clifford I. Voss, Tristan Wellman

Understanding the role of permafrost in controlling groundwater flow paths and fluxes is central in studies aimed at assessing potential climate change impacts on vegetation, species habitat, biogeochemical cycling, and biodiversity. Recent field studies in interior Alaska show evidence of hydrologic changes hypothesized to result from permafrost degradation. This study assesses the hydrologic control exerted by permafrost, elucidates modes of regional groundwater flow for various spatial permafrost patterns, and evaluates potential hydrologic consequences of permafrost degradation. The Yukon Flats Basin (YFB), a large (118,340 km2) subbasin within the Yukon River Basin, provides the basis for this investigation. Model simulations that represent an assumed permafrost thaw sequence reveal the following trends with decreasing permafrost coverage: (1) increased groundwater discharge to rivers, consistent with historical trends in base flow observations in the Yukon River Basin, (2) potential for increased overall groundwater flux, (3) increased spatial extent of groundwater discharge in lowlands, and (4) decreased proportion of suprapermafrost (shallow) groundwater contribution to total base flow. These trends directly affect the chemical composition and residence time of riverine exports, the state of groundwater-influenced lakes and wetlands, seasonal river-ice thickness, and stream temperatures. Presently, the YFB is coarsely mapped as spanning the continuous-discontinuous permafrost transition that model analysis shows to be a critical threshold; thus, the YFB may be on the verge of major hydrologic change should the current permafrost extent decrease. This possibility underscores the need for improved characterization of permafrost and other hydrogeologic information in the region via geophysical techniques, remote sensing, and ground-based observations.

PRISM marine sites—The history of PRISM sea surface temperature estimation

Released September 19, 2018 14:00 EST

2018, Open-File Report 2018-1148

Marci M. Robinson, Harry J. Dowsett, Kevin M. Foley, Christina R. Riesselman

For more than three decades, the U.S. Geological Survey (USGS) Pliocene Research, Interpretation and Synoptic Mapping (PRISM) Project has compiled paleoenvironmental data with the goal of reconstructing global conditions during the warm interval in the middle of the Piacenzian Age of the Pliocene Epoch (about 3.3 to 3.0 million years ago). Because this is the most recent interval of time in which climatic conditions were similar to those expected in the near future, a global reconstruction of conditions from this interval offers an imperfect yet useful representation of near future conditions. PRISM reconstructions have been used extensively as boundary conditions in general circulation model experiments aimed at better understanding Pliocene climate. They have also served as hindcasting targets when testing the ability of climate models to simulate real climates of the past, an exercise in estimating a model’s ability to accurately predict future climate. As data coverage has grown and model precision has improved, PRISM datasets have become important validation tools for pinpointing discrete areas of data-model disagreement and model-model disagreement. The Pliocene sea surface temperature (SST) dataset is the best developed component of the PRISM reconstructions and is the keystone of Pliocene paleoclimate research. For the first time, we compile all data related to PRISM SST estimation. This discussion chronicles the history of PRISM SST research as it evolved, responding to advances in paleochronology and paleotemperature estimation. Paleoclimatic considerations unique to each location are illustrated, as are any new developments since the initial publication of the data.

New insights into surface-water/groundwater exchanges in the Guadalupe River, Texas, from floating geophysical methods

Released September 19, 2018 10:26 EST

2018, Fact Sheet 2018-3057

Scott J. Ikard, J. Ryan Banta, Gregory P. Stanton

In south-central Texas, the amount of streamflow in the Guadalupe River is a primary concern for local and downstream communities because of municipal, agricultural, wildlife, and recreational uses. Understanding the flow paths and rates of exchange between the surface water in the river and the groundwater in the underlying Carrizo-Wilcox aquifer is vital for understanding the water budget and streamflow variations. In areas where the Guadalupe River crosses the Carrizo-Wilcox aquifer outcrop, the surface-water and groundwater exchanges are not well characterized. Traditional methods to measure these interactions, such as measuring differences in surface-water flows at different locations to infer gains and losses between the locations, are not feasible along this stretch of the Guadalupe River because of upstream dams that cause large daily fluctuations in streamflow. Consequently, the U.S. Geological Survey, in cooperation with the Guadalupe-Blanco River Authority, applied geophysical methods in an exploratory study to identify reaches of the river where streamflow gains and losses (surface-water/groundwater exchanges) might be occurring.

Wastewater indicators, hormones, sterols, antibiotics, and pharmaceuticals in soil at an agricultural field irrigated with domestic septage, central Minnesota, September 2014

Released September 19, 2018 10:24 EST

2018, Scientific Investigations Report 2018-5100

Sarah M. Elliott, Melinda L. Erickson, Aliesha L. Krall, Byron A. Adams

Treated domestic septage can be used to irrigate agricultural fields as a disposal method or as a means to reuse water. Because traditional on-site treatment systems are not designed to remove wastewater indicators, hormones, sterols, antibiotics, and pharmaceuticals, land application of septage potentially results in soil contamination. Soils were collected and analyzed from four sites in a central Minnesota agricultural field irrigated with domestic septage. Soil samples were analyzed for 111 unique contaminants, including wastewater indicators, hormones, sterols, antibiotics, and pharmaceuticals. In total, 32 contaminants were detected in soil samples. Several wastewater indicators were detected in soil, including fragrances, alkylphenols, and flame-retardants, at concentrations ranging from 1 (2,6-dimethylnaphthalene at soil site 4) to 1,550 (β-sitosterol at soil site 1) micrograms per kilogram. Relative to the number of contaminants analyzed, steroid hormones had the most frequent detections in soil samples (33 percent), and androgens were more prevalent compared to estrogens (50 and 22 percent, respectively). Androgens and estrogens were detected at concentrations ranging from 0.21 (estrone at soil site 3) to 3.9 (dihydrotestosterone at soil site 1) micrograms per kilogram. Quantifiable concentrations of antibiotics and pharmaceuticals ranged from 1.4 (carbamazepine at soil site 1) to 540 (azithromycin at soil site 3) micrograms per kilogram. Two antibiotics, ciprofloxacin and ofloxacin, were detected at concentrations above the limit of quantification (greater than 1,000 micrograms per kilogram at soil sites 2 and 3). This pilot sampling indicates that soils may be a repository for some contaminants introduced to the environment through land application of domestic septage.

A snapshot of women of the U.S. Geological Survey in STEM and related careers

Released September 19, 2018 08:45 EST

2018, Circular 1443

Susan C. Aragon-Long, Virginia R. Burkett, Holly S. Weyers, Susan M. Haig, Marjorie S. Davenport, Kelly L. Warner


The term “STEM” has been used to group together the fields of science, technology, engineering, and mathematics and to describe education and professions related to these fields. The professional fields connected to STEM education are thought of as engineering, medicine, and computer technology. Yet these professional fields are merely the tip of the iceberg. Numerous opportunities in these fields encompass environmental research. The possibilities range from predicting the next earthquake to saving polar bears from extinction to developing a vaccine for salmon measles.

The science of natural systems is complex and often requires people from a variety of fields of expertise to make headway with a solution. To that end, the U.S. Geological Survey (USGS) has long recognized the need for a diversity of STEM expertise to address the Nation’s environmental research needs and the vision to facilitate integration of these fields. We are team builders!

In this book, we point out the many facets of research carried out by USGS STEM scientists in an effort to show career options and pathways not typically pursued. The women portrayed were selected by USGS associate and regional directors as representative of particular fields and to inspire future generations.

Field expectations and the determination of wildcat drilling

Released September 18, 2018 14:22 EST

1977, Southern Economic Journal (44) 53-67

Emil Attanasi, L. J. Drew

There is currently some dissatisfaction with macroeconomic approaches to modeling the supply of domestic crude oil. One problem that has been pointed out is that the estimated supply responses of new discoveries brought about by price increases appear to be unrealistically high. Because data  frequently  used in these models  are highly aggregated over time and include diverse geologic regions, this criticism may not be unwarranted.  Moreover, with highly aggregated data testable hypotheses relating to operator behavior at the field level are limited. Because of the somewhat decentralized  nature of firm decision making, operator field behavior significantly affects the wildcat drilling rate and hence the interarrival times, i.e., temporal sequence, of expected discoveries.

Tradeoffs of a portable, field-based environmental DNA platform for detecting invasive northern pike (Esox lucius) in Alaska

Released September 18, 2018 13:57 EST

2018, Management of Biological Invasions (9) 253-258

Adam J. Sepulveda, Patrick R. Hutchins, Robert L. Massengill, Kristine J. Dunker

Environmental DNA (eDNA) has improved detection probabilities of aquatic invasive species but lab-based analytical
platforms for eDNA analyses slow opportunities for rapid response. Effective approaches that address this analytical
bottleneck and improve capacity for rapid response are urgently needed. We tested the sensitivity of a portable, field-based
eDNA platform relative to widely used lab-based eDNA approaches for detecting invasive northern pike (Esox lucius) in
eight lakes on Alaska’s Kenai Peninsula. The portable, field-based platform takes ~ 1 hr from sample collection to final results
and uses a field-based DNA extraction kit, a shelf-stable assay, and a portable real-time PCR thermocycler. Lab-based
approaches take days to weeks to months for final results and use lab-based DNA extraction kits, lab-bound assays, and
benchtop real-time thermocyclers. We found that the portable, field-based approach was less sensitive than lab-based
approaches and was more prone to inhibition, thus increasing potential for false-negatives. Until sensitivity and inhibition
issues can be resolved, this portable, field-based approach is best viewed as a complement to rather than a replacement of
standard eDNA lab-based approaches.

A bioenergetics evaluation of temperature‐dependent selection for the spawning phenology by Snake River fall Chinook salmon

Released September 18, 2018 13:52 EST

2018, Ecology and Evolution

John M. Plumb

High water temperatures can increase the energetic cost for salmon to migrate and spawn, which can be important for Snake River fall‐run Chinook salmon because they migrate great distances (>500 km) at a time when river temperatures (18–24°C) can be above their optimum temperatures (16.5°C). Average river temperatures and random combinations of migration and spawning dates were used to simulate fish travel times and determine the energetic consequences of different thermal experiences during migration. An energy threshold criterion (4 kJ/g) was also imposed on survival and spawning success, which was used to determine how prevailing temperatures might select against certain migration dates and thermal experiences, and in turn, explain the selection for the current spawning phenology of the population. Scenarios of tributary use for thermal refugia under increasing water temperatures (1, 2, and 3°C) were also run to determine which combinations of migration dates, travel rates, and resulting thermal experiences might be most affected by energy exhaustion. As expected, when compared to observations, the model under existing conditions and energy use could explain the onset, but not the end of the observed spawning migration. Simulations of early migrants had greater energy loss than late migrants regardless of the river temperature scenario, but higher temperatures disproportionately selected against a larger fraction of early‐migrating fish, although using cold‐water tributaries during migration provided a buffer against higher energy use at higher temperatures. The fraction of simulated fish that exceeded the threshold for migration success increased from 58% to 72% as average seasonal river temperatures over baseline temperatures increased. The model supports the conclusion that increases in average seasonal river temperatures as little as 1°C could impose greater thermal constraints on the fish, select against early migrants, and in turn, truncate the onset of the current spawning migration.

Survey-based assessment of the frequency and potential impacts of recreation on polar bears

Released September 18, 2018 13:47 EST

2018, Biological Conservation (227) 121-132

Karyn D. Rode, Jennifer K. Fortin, Dave Garshelis, Markus Dyck, Vicki Sahanatien, Todd C. Atwood, Stanislav Belikov, Kristin L. Laidre, Susanne Miller, Martyn E. Obbard, Dag Vongraven, Jasmine V. Ware, James Wilder

Conservation plans for polar bears (Ursus maritimus) typically cannot prescribe management actions to address their primary threat: sea ice loss associated with climate warming. However, there may be other stressors that compound the negative effects of sea ice loss which can be mitigated. For example, Arctic tourism has increased concurrent with polar bears increasingly using terrestrial habitats, which creates the potential for increased human-bear interactions. Little is known about the types, frequency, or potential impacts of recreation. We conducted a Delphi survey among experts who live and work in polar bear habitats, followed by an internet-based survey to which 47 managers, tour operators, community members, and scientists contributed. Participants identified viewing-based recreation as increasing and affecting the largest proportion of bears within subpopulationsthat come ashore during the ice-free season. Survey respondents suggested that negative effects of viewing, including displacement and habituation, could be reduced by restricting human use areas and distances between bears and people. Killing of bears in defense was associated more with camping or hunting for other species than other recreations, and may be mitigated with deterrents. Snowmobiling was the most common recreation across the polar bears' range, and reportedly caused some den abandonment and displacement. However, respondents estimated that <10% of polar bears are exposed to most types of recreation and <50% surmised any negative impacts. Nevertheless, mitigating some of the negative impacts identified in this study may become increasingly important as polar bears cope with sea ice loss.

Developing hydro-meteorological thresholds for shallow landslide initiation and early warning

Released September 18, 2018 13:43 EST

2018, Water (10) 1-19

Benjamin B. Mirus, Michael D. Morphew, Joel B. Smith

Consistent relations between shallow landslide initiation and associated rainfall characteristics remain difficult to identify, due largely to the complex hydrological and geological processes causing slopes to be predisposed to failure and those processes that subsequently trigger failures. Considering the importance of hillslope hydrology for rainfall-induced landsliding, we develop and test a method for identifying hybrid hydro-meteorological thresholds to assess landslide initiation potential. We outline a series of steps for using a landslide inventory in combination with triggering rainfall and antecedent wetness to identify empirical thresholds that can inform landslide early warning systems. The method is semi-automated but remains flexible enough to allow threshold developers to consider data inputs and various performance metrics with different priorities for balancing failed versus false alarms. We demonstrate the utility of our approach for two monitoring sites near Seattle, Washington and in Portland, Oregon, USA, to develop daily bilinear thresholds within a two-dimensional parameter space, which rely on accurate 24 h forecasts, measured recent rainfall and in situ soil saturation. Although there were no prior landslide thresholds for Portland, our new hybrid threshold for the Seattle area outperforms established rainfall-only thresholds for the same region. Introducing subsurface hydrologic monitoring into landslide initiation thresholds has the potential to greatly improve early warning capabilities and help reduce losses.

Decadal topographic change in the McMurdo Dry Valleys of Antarctica: Thermokarst subsidence, glacier thinning, and transfer of water storage from the cryosphere to the hydrosphere

Released September 18, 2018 13:35 EST

2018, Geomorphology (323) 80-97

J.S. Levy, A.G. Fountain, Maciej Obryk, J. Telling, C. Glennie, R. Pettersson, M. Gooseff, D.J. van Horn

Recent local-scale observations of glaciers, streams, and soil surfaces in the McMurdo Dry Valleys of Antarctica (MDV) have documented evidence for rapid ice loss, glacial thinning, and ground surface subsidence associated with melting of ground ice. To evaluate the extent, magnitude, and location of decadal-scale landscape change in the MDV, we collected airborne lidar elevation data in 2014–2015 and compared these data to a 2001–2002 airborne lidar campaign. This regional assessment of elevation change spans the recent acceleration of warming and melting observed by long-term meteorological and ecosystem response experiments, allowing us to assess the response of MDV surfaces to warming and potential thawing feedbacks. We find that locations of thermokarst subsidence are strongly associated with the presence of excess ground ice and with proximity to surface or shallow subsurface (active layer) water. Subsidence occurs across soil types and landforms, in low-lying, low-slope areas with impeded drainage and also high on steep valley walls. Glacier thinning is widespread and is associated with the growth of fine-scale roughness. Pond levels are rising in most closed-basin lakes in the MDV, across all microclimate zones. These observations highlight the continued importance of insolation-driven melting in the MDV. The regional melt pattern is consistent with an overall transition of water storage from the local cryosphere (glaciers, permafrost) to the hydrosphere (closed basin lakes and ponds as well as the Ross Sea). We interpret this regional melting pattern to reflect a transition to Arctic and alpine-style, hydrologically mediated permafrost and glacial melt.

Population differences in susceptibility to Plasmodium relictum in zebra finches Taeniopygia guttata

Released September 18, 2018 13:32 EST

2018, Avian Diseases

Erik K. Hofmeister, Christopher N. Balakrishnan, Carter T. Atkinson

Domesticated Australian and Timor zebra finches (Taeniopygia guttata castanotis, and T. guttata guttata, respectively) were inoculated with canary (Serinus canaria) blood containing a Hawaiian isolate of Plasmodium relictum (lineage GRW04), a hemoparasite that causes avian malaria. In two experimental trials, Timor, but not Australian zebra finches developed parasitemia that was detected by microscopic examination of blood smears. In the second trial, in which molecular detection methods were used, a single Australian zebra finch and 5 of 6 challenged Timor birds were positive for the parasite. Additionally, P. relictum DNA was detected in multiple blood samples obtained from Timor birds over the 28 days following challenge. Timor zebra finches may provide a useful, easily maintained, laboratory model for the study of arbovirus/Plasmodium interactions in passerines, but are still inferior to canaries, the traditionally used model of avian malaria infection, in terms of supporting high parasitemia infections.

Hydrologic conditions in Kansas, water year 2017

Released September 18, 2018 08:37 EST

2018, Fact Sheet 2018-3060

Bradley S. Lukasz

The U.S. Geological Survey, in cooperation with Federal, State, and local agencies, maintains a long-term network of hydrologic monitoring stations in Kansas. These data and associated analyses provide a unique overview of the hydrologic conditions and help improve the understanding of Kansas’ water resources. Yearly assessments of hydrologic conditions are made by comparing statistical analysis of current and past water year data for the period of record. These data provide critical information for protecting life and property, managing water supplies, forecasting floods, operating reservoirs, designing bridges and culverts, processing interstate and intrastate water rights claims, ecological monitoring, and many other uses.

Holocene fault reactivation in the eastern Cascades, Washington

Released September 17, 2018 15:07 EST

2018, Bulletin of the Seismological Society of America (108) 2614-2633

Benjamin L. Carlson, Elizabeth R. Schermer, Colin B. Amos, William J. Stephenson, Brian Sherrod, Shannon A. Mahan

Significant uncertainty remains concerning how and where crustal shortening occurs throughout the eastern Cascade Range in Washington State. Using light detection and ranging (lidar) imagery, we identified an ∼5‐km‐long lineament in Swakane canyon near Wenatchee, roughly coincident with a strand of the Entiat fault. Topographic profiles across the lineament reveal a southwest‐side‐up break in slope, with an average of 2–3 m of vertical separation of the hillslope surface. We consider a range of possible origins for this feature, including differential erosion across a fault‐line scarp, slope failure (sackung or landslide), and surface deformation across an active fault strand. Based on trenching, radiocarbon and luminescence dating, and ground‐penetrating radar (GPR) across the lineament, we conclude that warped saprolite observed in the shallow subsurface is most consistent with southwest‐side‐up folding caused by blind reverse faulting at depth. Following this reasoning, dating of overlying colluvial deposits suggests that at least one Holocene earthquake occurred on this strand of the southern Entiat fault, with an approximate vertical separation of m≥1  m. GPR reveals up to 4 m of cumulative vertical separation of the saprolite, suggesting a history of multiple earthquakes on the structure. Taken in context with other potential fault‐related lineaments along the Entiat fault, our interpretation of Holocene earthquakes in Swakane canyon could suggest reactivation of longer sections of the Entiat fault, as well as of other bedrock faults in the eastern Cascades. Although active erosion and slow strain rates lead to a subdued geomorphic expression of recent deformation, we conclude that the reactivated Entiat fault represents a seismogenic structure that should be considered in regional seismic hazard analyses. The difficulty of recognizing low‐slip‐rate structures in forested and mountainous terrain underscores the importance of additional lidar surveys and geological and geophysical studies for fully understanding seismic hazard in regions with infrequent but potentially large earthquakes.

A review of coastal management approaches to support the integration of ecological and human community planning for climate change

Released September 17, 2018 13:55 EST

2018, Journal of Coastal Conservation

Emily J. Powell, Megan C. Tyrrell, Andrew Milliken, John M. Tirpak, Michelle D. Staudinger

The resilience of socio-ecological systems to sea level rise, storms and flooding can be enhanced when coastal habitats are used as natural infrastructure. Grey infrastructure has long been used for coastal flood protection but can lead to unintended negative impacts. Natural infrastructure often provides similar services as well as added benefits that support short- and long-term biological, cultural, social, and economic goals. While natural infrastructure is becoming more widespread in practice, it often represents a relatively small fraction within portfolios of coastal risk-reducing strategies compared to more traditional grey infrastructure. This study provides a comprehensive review of how natural infrastructure is being used along the United States Atlantic, Gulf of Mexico, and Caribbean coasts related to four habitats – tidal marshes, beaches and barrier islands, mangroves, and biogenic reefs. We compare information on the benefits, opportunities and challenges of implementing natural, grey and hybrid infrastructure in the coastal zone. In addition, we present a suite of actions to increase information and reduce uncertainty so that coastal mangers and planners are aware of the full suite of options for restoration, conservation and planning that maximize ecosystem services over short- and long-term planning horizons.

A database of natural monthly streamflow estimates from 1950 to 2015 for the conterminous United States

Released September 17, 2018 13:52 EST

2018, Journal of the American Water Resources Association

Matthew P. Miller, Daren M. Carlisle, David M. Wolock, Michael Wieczorek

Quantifying and understanding the natural streamflow regime, defined as expected streamflow that would occur in the absence of anthropogenic modification to the hydrologic system, is critically important for the development of management strategies aimed at protecting aquatic ecosystems. Water balance models have been applied frequently to estimate natural flows, but are limited in the number of predictor variables that can be included. Here, a statistical machine learning technique — random forest modeling — was applied to estimate natural flows at a monthly time‐step from 1950 to 2015 for >2.5 million stream reaches in the conterminous United States (U.S.) using 200 potential predictor variables. We describe the development and documentation of this dataset and assess model performance. Model fit statistics (mean Nash–Sutcliffe efficiency = 0.85; observed/expected ratio = 0.94) indicate good correspondence between predicted and observed flows at nearly 2,000 streamgages. As an example application of the dataset, the observed streamflow record at a site prior to and after the construction of an upstream reservoir was compared with estimated natural flows to demonstrate the magnitude of seasonal depletions in streamflow due to the reservoir. This dataset can be applied to quantify natural and anthropogenic processes contributing to streamflow depletion or augmentation, and assess associated ecological effects.

Identifying physics‐based thresholds for rainfall‐induced landsliding

Released September 17, 2018 13:45 EST

2018, Geophysical Research Letters

Matthew A. Thomas, Benjamin B. Mirus, Brian D. Collins

Most regional landslide warning systems utilize empirically derived rainfall thresholds that are difficult to improve without recalibration to additional landslide events. To address this limitation, we explored the use of synthetic rainfall to generate thousands of possible storm patterns and coupled them with a physics‐based hydrology and slope stability model for various antecedent soil saturation scenarios to analyze pore‐water pressure and factor of safety metrics. We used these metrics to generate two‐tiered alert thresholds that can be employed to assess shallow landslide potential for any given combination of storm and antecedent wetness. When applied to the San Francisco Bay region (California, USA), the results are consistent with events that caused widespread landsliding. Our deterministic modeling approach, which accounts for plausible ranges in soil hydraulic and mechanical properties, can inform the development of the next generation of warning systems for rainfall‐induced landsliding.

Rhizophagy cycle: An oxidative process in plants for nutrient extraction from symbiotic microbes

Released September 17, 2018 13:42 EST

2018, Microorganisms (6) 1-20

James F. White, Kathryn L. Kingsley, Satish K. Verma, Kurt P. Kowalski

In this paper, we describe a mechanism for the transfer of nutrients from symbiotic microbes (bacteria and fungi) to host plant roots that we term the ‘rhizophagy cycle.’ In the rhizophagy cycle, microbes alternate between a root intracellular endophytic phase and a free-living soil phase. Microbes acquire soil nutrients in the free-living soil phase; nutrients are extracted through exposure to host-produced reactive oxygen in the intracellular endophytic phase. We conducted experiments on several seed-vectored microbes in several host species. We found that initially the symbiotic microbes grow on the rhizoplane in the exudate zone adjacent the root meristem. Microbes enter root tip meristem cells—locating within the periplasmic spaces between cell wall and plasma membrane. In the periplasmic spaces of root cells, microbes convert to wall-less protoplast forms. As root cells mature, microbes continue to be subjected to reactive oxygen (superoxide) produced by NADPH oxidases (NOX) on the root cell plasma membranes. Reactive oxygen degrades some of the intracellular microbes, also likely inducing electrolyte leakage from microbes—effectively extracting nutrients from microbes. Surviving bacteria in root epidermal cells trigger root hair elongation and as hairs elongate bacteria exit at the hair tips, reforming cell walls and cell shapes as microbes emerge into the rhizosphere where they may obtain additional nutrients. Precisely what nutrients are transferred through rhizophagy or how important this process is for nutrient acquisition is still unknown.

Mapping the relationships between trail conditions and experiential elements of long-distance hiking

Released September 17, 2018 13:39 EST

2018, Landscape and Urban Planning (180) 60-75

Brian A. Peterson, Matthew T.J. Brownlee, Jeffrey L. Marion

Trail users that experience acceptable social and ecological conditions are more likely to act as trail stewards, exhibit proper trail etiquette, and use low-impact practices. However, the relationships between specific trail conditions and experiential elements of long-distance hiking are not well understood. Therefore, the purpose of this study was to identify how trail conditions influence particular elements of the long-distance hiking experience. The researchers used a mixed-methods approach involving semi-structured interviews (n = 17), quantitative questionnaires (n = 336), ecological measurements of trail conditions (n = 21–5 km sections), and modified Recreation Suitability Mapping (RSM) techniques to quantify the relationships between five trail conditions (trail incision, muddiness, rugosity, trail width, and gradient) and four experiential elements of long-distance hiking (level of challenge, perceived impact to musculoskeletal system, valuation of tread aesthetics, and ability to maintain an ideal hiking pace). Quantified values were weighted, analyzed, and mapped using SPSS 22.0 and ArcMap 10.2.2. Significant differences exist in the scores and distributions of ecological measures across all sections, indicating that trail conditions vary significantly across sampled trail sections. Although, long-distance hikers felt all four experiential elements were important, tread aesthetics was ranked by 50.2% of sampled hikers as the most important experiential element to the overall experience. The resulting information after applying the weights suggests what particular type of experience is likely for each trail section considering the presence of trail conditions.

Mortality of little brown bats (Myotis lucifugus carissima) naturally exposed to microcystin-LR

Released September 17, 2018 13:24 EST

2018, Journal of Wildlife Diseases

Marcos Isidoro Ayza, Lee C. Jones, Robert Dusek, Jeffrey M. Lorch, Jan H. Landsberg, Patrick Wilson, Stephanie Graham

We describe a die-off of little brown bats (Myotis lucifugus carissima) associated with acute intoxication with microcystin-LR in 2016 at Scofield Reservoir in Utah. High levels of this cyanotoxin in water from the reservoir and gastrointestinal content of bats supported this diagnosis.

Science for a risky world—A U.S. Geological Survey plan for risk research and applications

Released September 17, 2018 11:53 EST

2018, Circular 1444

Kristin A. Ludwig, David W. Ramsey, Nathan J. Wood, Alice B. Pennaz, Jonathan W. Godt, Nathaniel G. Plant, Nicolas Luco, Todd A. Koenig, Kenneth W. Hudnut, Donyelle K. Davis, Patricia R. Bright

Executive Summary

Natural hazards—including earthquakes, tsunamis, volcanic eruptions, landslides, hurricanes, droughts, floods, wildfires, geomagnetic storms, and pandemics—can wreak havoc on human communities, the economy, and natural resources for years following an initial event. Hazards can claim lives and cause billions of dollars in damage to homes and infrastructure as well as lost or compromised economic activity and threats to national security. They also can have adverse environmental, social, economic, and health effects that extend well beyond the immediate area, sometimes with global implications. Changes in population growth, climate, and urbanization may exacerbate hazard impacts.

Because of the potential severity of a single hazard event, reducing risk—the potential loss of societally important assets caused by these hazards—is a high priority for everyone, including policy makers, community members, emergency managers, resource managers, utility operators, business owners, and planners. These stakeholders demand usable, user-centric information to support decisions for planning a resilient future and for responding to and recovering from unanticipated events in more adaptable and cost-effective ways.

Meeting this demand requires maximizing the use of environmental observations; hazards science; and research on communications, social stressors, and human behavior to deliver risk information in forms that are accessible by decision makers and the public alike. To achieve this, scientists and stakeholders must collaborate to match community needs with actionable insights, research, products, and tools, using advances in technology to improve information discovery and delivery.

Continuous stream discharge, salinity, and associated data collected in the lower St. Johns River and its tributaries, Florida, 2016

Released September 17, 2018 08:52 EST

2018, Open-File Report 2018-1108

Patrick J. Ryan

The U.S. Army Corps of Engineers, Jacksonville District, plans to deepen the St. Johns River channel in Jacksonville, Florida, from 40 to 47 feet along 13 miles of the river channel, beginning at the mouth of the river at the Atlantic Ocean, to accommodate larger, fully loaded cargo vessels. The U.S. Geological Survey installed continuous data-collection stations to monitor discharge, salinity, and associated parameters at 22 sites prior to the commencement of dredging. The U.S. Geological Survey monitored stage and discharge at 13 sites, and water temperature, specific conductance, and salinity at 15 sites; some sites included all parameters.

This report contains information pertinent to the data collection sites from their installation date to September 2016, with additional information and data from Hurricane Matthew in October 2016. Site installations began in October 2015; all sites were installed and began collecting data by January 2016. All data available for each site after October 2015 are included in this report.

Discharge and salinity ranged widely during the data collection period, which included the effects of Hurricane Hermine in September 2016 and Hurricane Matthew in October 2016. Of the tributaries, annual mean discharge was greatest at Ortega River, followed by Cedar River, Julington Creek, Durbin Creek, and Clapboard Creek. Annual mean salinity for the main-stem sites indicates that salinity decreases with distance upstream, which is expected. The closest tributary site to the Atlantic Ocean (Clapboard Creek) produced the highest annual mean salinity of the tributaries, and Durbin Creek salinity was the lowest of all monitoring locations.