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Demonstrating the Value of Earth Observations—Methods, Practical Applications, and Solutions—Group on Earth Observations Side Event Proceedings

Released April 19, 2019 11:30 EST

2019, Open-File Report 2019-1033

Francoise Pearlman, Collin B. Lawrence, Emily J. Pindilli, Denna Geppi, Carl D. Shapiro, Monica Grasso, Jay Pearlman, Jeffery Adkins, Geoff Sawyer, Alessandra Tassa

Executive Summary

The U.S. Geological Survey, the National Oceanic and Atmospheric Administration, the European Association for Remote Sensing Companies, and the European Space Agency in coordination with the GEOValue Community hosted a side event to the Group on Earth Observations Plenary on October 23–24, 2017, in Washington, D.C. The workshop, entitled “Demonstrating the Value of Earth Observations: Methods, Practical Applications and Solutions,” brought together more than 60 international experts including economists, scientists, and engineers to consider the state of the science and applications of valuing Earth observations (EO).

This 2-day workshop built upon previous activities developed under the GEOValue initiative. This workshop brought together expert analysts from multiple disciplines and backgrounds who are developing methods to identify and measure the value of information generated from the use of satellite and in-situ data. The mix of government agencies, international financial institutions, and independent consultants who participated in the workshop blended to develop a rich mix of views, approaches, and outcomes.

During the first part of the workshop, the focus was on the latest science in valuing EO. A number of methodologies were described. Approaches generally assess the societal benefits of specific actions (for example, investments in EO). Some methods focus on broad measures of economic activity (for example, gross domestic product) or methods to assess total economic value such as contingent valuation surveys. Alternatively, use-case approaches (a use case is defined as an evaluation in which one or more decisions, applications, or other uses of data, information, and information products are specifically considered) start with the specific actions and how information is used to support decision making and affect outcomes.

The second part of the meeting was focused on the use and development of value chains and decision trees. A value chain can be defined as the set of value-adding activities that one or more organizations perform in creating and distributing goods and services. In terms of EO, the value chain approach can be applied to consider societal benefits of the data and assess the value of data and data features. The EO value chain considers the geospatial data sources and the processing of the data into value added information to be incorporated into decision-support systems, leading to decision makers’ actions. To understand the value of EO, one would also need to recognize the demand side of the equation or how EO benefits users. Extending the value chain concept and incorporating tenets of Bayesian decision making, a decision tree would include one or more use cases. The value provided by the marginal increase in information could flow from one or several parts of the supply side of the value chain. The decision tree is based on the premise that information has no value if it is not used in at least one decision. By connecting the value chain and the decision tree, a framework is created that allows for conceptualizing the value of EO in its many uses. One can then apply economic techniques to monetize the marginal benefit of an outcome with information versus one without.

A third part of the meeting applied the value chain and decision-tree frameworks to five specific thematic areas, each with the focus of using information for a decision point:

  • Effect of increasing temperatures on human health;
  • Flooding—Mitigating, managing, and avoiding impacts to safety and property damage;
  • Harmful algal blooms—Effects on human health, recreation, and tourism;
  • Energy and mineral supply—Mitigating, managing, and avoiding impacts of shortfalls on the economy; and
  • Effects of natural hazards on transportation systems—Effects on mobility, safety, and the economy.

During the working session, five separate groups worked to define and delineate the value chains and decision trees associated with each topic, discussing the related challenges and data needs. The outcomes were reported back to the full group. Because of the complexity of the topics, most groups first identified a network of value chains and then narrowed the scope to develop a single value chain to address their group’s topic. Although they worked separately and on different topics, the groups came to similar conclusions, concurring that the value chain and decision-tree frameworks are very effective for informing quantitative impact assessments and developing a relatable narrative to assist the public in understanding the link between EO and citizens.

Drinking Water Health Standards Comparison and Chemical Analysis of Groundwater for 72 Domestic Wells in Bradford County, Pennsylvania, 2016

Released April 19, 2019 08:45 EST

2019, Scientific Investigations Report 2018-5170

John W. Clune, Charles A. Cravotta III

Pennsylvania has the second highest number of residential wells of any state in the Nation with approximately 2.4 million residents that depend on groundwater for their domestic water supply. Despite the widespread reliance on groundwater in rural areas of the state, publicly available data to characterize the quality of private well water are limited. In Bradford County, more than half of the residents use groundwater from private domestic-supply wells as their primary drinking source. The quality of private well water is influenced by the regional and local setting, including the surrounding soil, geology, land use, household plumbing, and well construction. The groundwater used for domestic water supply in Bradford County is obtained primarily from shallow bedrock and from unconsolidated (glacial) deposits that overlie the bedrock. Historical land use has been predominately forested, agricultural, and residential, but more recently unconventional oil/gas development has been distributed throughout the landscape. Pennsylvania is one of only two states in the Nation without statewide water-well construction standards.

To better assess the quality of groundwater used for drinking water supply in Bradford County, data for 72 domestic wells were collected and analyzed for a wide range of constituents that could be evaluated in relation to drinking water health standards, geology, land use, and other environmental factors. Groundwater samples were collected from May through August 2016 and analyzed for physical and chemical properties, including major ions, nutrients, trace elements, volatile organic compounds, ethylene and propylene glycol, alcohols, gross-alpha/beta-particle activity, uranium, radon-222, and dissolved gases. A subset of samples was analyzed for radium isotopes (radium-226 and -228) and for the isotopic composition of methane. This study was conducted by the U.S. Geological Survey in cooperation with the Northern Tier Regional Planning and Development Commission and is part of a regional effort to characterize groundwater in rural areas of Pennsylvania.

Results of the 2016 study show that groundwater quality generally met most drinking-water standards. However, a percentage of samples failed to meet maximum contaminant levels (MCLs) for total coliform bacteria (49.3 percent), Escherichia coli (8.5 percent), barium (2.8 percent), and arsenic (2.8 percent); and secondary maximum contaminant levels (SMCL) for sodium (48.6 percent), manganese (30.6 percent), gross alpha and beta activity (16.7 percent), iron (11.1 percent), pH (8.3 percent), total dissolved solids (5.6 percent), chloride (1.4 percent), and aluminum (1.4 percent). Radon-222 activities exceeded the proposed drinking-water standard of 300 picocuries per liter (pCi/L) in 70.4 percent of the samples. There were no exceedances of drinking water health standards for any volatile organic compounds, and the only detections were for three trihalomethanes in one sample.

The pH of the groundwater had a large influence on chemical characteristics and ranged from 6.18 to 9.31. Generally, the higher pH samples had higher potential for elevated concentrations of several constituents, including total dissolved solids, sodium, lithium, chloride, fluoride, boron, arsenic, and methane. For the Bradford County well-water samples, calcium/bicarbonate type waters were most abundant, with others classified as sodium/bicarbonate or mixed water types including calcium-sodium/bicarbonate, calcium-sodium/bicarbonate-chloride, sodium/bicarbonate-chloride, sodium/bicarbonate-sulfate, or sodium/chloride types. Six principal components (pH, redox, hardness, chloride-bromide, strontium-barium, and molybdenum-arsenic) explained nearly 78.3 percent of the variance in the groundwater dataset.

Groundwater from 12.5 percent of the wells had concentrations of methane greater than the Pennsylvania action level of 7 milligrams per liter (mg/L); detectable methane concentrations ranged from 0.01 to 77 mg/L. In addition, low levels of ethane (as much as 0.13 mg/L) were present in seven samples with the highest methane concentrations. The isotopic composition of methane in five of these groundwater samples was consistent with the isotopic compositions reported for mud-gas logging samples from these geologic units and a thermogenic source. Isotopic composition from a sixth sample suggested the methane in that sample may be of microbial origin. Well-water samples with the higher methane concentrations also had higher pH values and elevated concentrations of sodium, lithium, boron, fluoride, arsenic, and bromide. Relatively elevated concentrations of some other constituents, such as barium and chloride, commonly were present in, but not limited to, those well-water samples with elevated methane.

Four of the six groundwater samples with the highest methane concentrations had chloride/bromide ratios that indicate mixing with a small amount of brine (0.02 percent or less) similar in composition to those reported for gas and oil well brines in Pennsylvania. In several other eastern Pennsylvania counties where gas drilling is absent, groundwater with comparable chloride/bromide ratios and chloride concentrations have been reported, implying a potential natural source of brine. The majority of Bradford County well-water samples, including the samples with the highest chloride concentrations, have chloride/bromide ratios that indicate predominantly anthropogenic sources of chloride, such as road-deicing salt or septic effluent. Brines that are naturally present may originate from deeper parts of the aquifer system, whereas anthropogenic sources are more likely to affect shallow groundwater because they occur on or near the land surface.

The available data for this study indicate that no one physical factor, such as the topographic setting, well depth, or altitude at the bottom of the well, was particularly useful for predicting those well locations with an elevated dissolved concentration of methane. The 2016 assessment of groundwater quality in Bradford County shows groundwater is generally of good quality, but methane and some constituents that occur in high concentration in naturally occurring brine and also in produced waters may be present at low to moderate concentrations in groundwater in various parts of the aquifer.

Landsat 9

Released April 18, 2019 14:47 EST

2019, Fact Sheet 2019-3008

U.S. Geological Survey

Landsat 9 is a partnership between the National Aeronautics and Space Administration (NASA) and the U.S. Geological Survey (USGS) that will continue the Landsat program’s critical role of repeat global observations for monitoring, understanding, and managing Earth’s natural resources. Since 1972, Landsat data have provided a unique resource for those who work in agriculture, geology, forestry, regional planning, education, mapping, and global-change research. Landsat images have also proved invaluable to the International Charter: Space and Major Disasters, supporting emergency response and disaster relief to save lives. With the addition of Landsat 9, the Landsat program’s record of land imaging will be extended to over half a century.

Derivation of cat embryonic stem-like cells from in vitro-produced blastocysts on homologous and heterologous feeder cells

Released April 18, 2019 14:33 EST

2010, Article

M.C. Gomez, M.A. Serrano, C. Earle Pope, Jill A. Jenkins, M.N. Biancardi, M. Lopez, C. Dumas, J. Galiguis, B.L. Dresser

The domestic cat is a focal mammalian species that is used as a model for developing assisted reproductive technologies for preserving endangered cats and for studying human diseases. The generation of stable characterized cat embryonic stem cells (ESC) lines to use as donor nuclei may help to improve the efficiency of interspecies somatic cell nuclear transfer for preserving endangered cats and allow the creation of knockout cell lines to generate knockout cats for studying function of specific genes related to human diseases. It will also enable the possibility of producing gametes in vitro from ESC of endangered cats. In the present study, we report the generation of cat embryonic stem-like (cESL) cells from blastocysts derived entirely in vitro. We generated 32 cESL cell lines from 331 in vitro derived blastocysts from which inner cell masses were isolated by immunosurgery or by a mechanical method. Inhibition of cat dermal fibroblast (CDF) proliferation after exposure to mitomycin-C was both dose and time dependent, where doses of 30 to 40 microg/mL for 5 h were most efficient. These dosages were higher than that required to inhibit cell proliferation of mouse fetal fibroblasts (MFF; 10 microg/mL for 2.5 h). Mitomycin-C did not significantly increase necrosis of cells from either species, and had an anti-proliferative effect at concentrations below cytotoxicity. A clear species-specific relationship between feeder layers and derivation of cESL cell lines was observed, where higher numbers of cESL cell lines were generated on homologous cat feeder layers (n = 26) than from those derived on heterologous mouse feeder layers (n = 6). Three cESL cell lines generated from immunosurgery and cultured on CDF maintained self-renewal and were morphologically undifferentiated for nine and twelve passages (69-102 days). These lines showed a tightly packed dome shaped morphology, exhibited alkaline phosphatase activity and immuno-expression of the pluripotent marker OCT-4 and surface marker SSEA-1. Primary colonies at P0 to P3 and cat blastocysts expressed transcription factors OCT-4, NANOG and SOX-2 and the proto-oncogene C-MYC. However, expression was at levels significantly lower than in vitro produced blastocysts. During culture, cESL colonies spontaneously differentiated into fibroblasts, cardiomyocytes, and embryoid bodies. Development of techniques to prevent differentiation of cESL cells will be essential for maintaining defined cell lines

Natural Resource and Ecosystem Costs of Coastal Hazards in The Hidden Costs of Coastal Hazards: Implications for Risk Assessment and Mitigation

Released April 18, 2019 13:54 EST

2000, Book chapter

H. Kunreuther, R. Platt, S. Baruch, R. Bernknopf, M. Buckley, V. Burkett, D. Conrad, T. Davidson, K. Deutsch, D. Geis, M. Jannereth, A. Knap, H. Lane, G. Ljung, M. McCauley, D. Mileti, T. Miller, B. Morrow, J. Meyers, R. A. Pielke, A. Pratt, J. Tripp

Society has limited hazard mitigation dollars to invest. Which actions will be most cost effective, considering the true range of impacts and costs incurred? In 1997, the H. John Heinz III Center for Science, Economics and the Environment began a two-year study with a panel of experts to help develop new strategies to identify and reduce the costs of weather-related hazards associated with rapidly increasing coastal development activities.

The Hidden Costs of Coastal Hazards presents the panel's findings, offering the first in-depth study that considers the costs of coastal hazards to natural resources, social institutions, business, and the built environment. Using Hurricane Hugo, which struck South Carolina in 1989, as a case study, it provides for the first time information on the full range of economic costs caused by a major coastal hazard event. The book:

  • describes and examines unreported, undocumented, and hidden costs such as losses due to business interruption, reduction in property values, interruption of social services, psychological trauma, damage to natural systems, and others
  • examines the concepts of risk and vulnerability, and discusses conventional approaches to risk assessment and the emerging area of vulnerability assessment
  • recommends a comprehensive framework for developing and implementing mitigation strategies
  • documents the human impact of Hurricane Hugo and provides insight from those who lived through it.

The Hidden Costs of Coastal Hazards takes a structured approach to the problem of coastal hazards, offering a new framework for community-based hazard mitigation along with specific recommendations for implementation. Decisionmakers -- both policymakers and planners -- who are interested in coastal hazard issues will find the book a unique source of new information and insight, as will private-sector decisionmakers including lenders, investors, developers, and insurers of coastal property.

Use of a Numerical Model to Simulate the Hydrologic System and Transport of Contaminants Near Joint Base Cape Cod, Western Cape Cod, Massachusetts

Released April 18, 2019 13:30 EST

2019, Scientific Investigations Report 2018-5139

Donald A. Walter, Timothy D. McCobb, Michael N. Fienen

Historical training and operational activities at Joint Base Cape Cod (JBCC) on western Cape Cod, Massachusetts, have resulted in the release of contaminants into an underlying glacial aquifer that is the sole source of water to the surrounding communities. Remedial systems have been installed to contain and remove contamination from the aquifer. Groundwater withdrawals for public supply are expected to increase as the region continues to urbanize. Increases in water-supply withdrawals and wastewater return flow likely will affect the hydrologic system around JBCC and could affect the transport of any contamination that may remain in the aquifer following remediation of contamination from the JBCC. The U.S. Geological Survey, in cooperation with the Air Force Civil Engineer Center, developed a numerical, steady-state regional model of the Sagamore flow lens on western Cape Cod and evaluated the potential effects of future (2030) groundwater withdrawals on water levels, streamflows, hydraulic gradients, and advective transport near the JBCC.

The aquifer consists generally of sandy sediments underlain by impermeable bedrock and is bounded laterally by a freshwater/saltwater interface. Data on the altitude of the bedrock surface, position of the freshwater/saltwater interface, lithology of the aquifer, spatial distribution of recharge, and hydrologic boundaries were incorporated into the three-dimensional, finite-difference groundwater flow model.

Some inputs into the numerical model—aquifer properties, leakances, and recharge—are represented as parameters to facilitate estimation of optimal parameter values in an inverse calibration. A hybrid parameterization scheme, with both zones of piecewise constancy and pilot points, is used to represent hydraulic conductivity; other adjustable parameters include recharge, boundary leakance, and porosity. Data on water levels, the distribution of subsurface contamination, and groundwater ages were compiled, evaluated, and used to develop observations of long-term average hydraulic gradients and advective-transport patterns. These observations of steady-state hydrologic conditions were combined with the parameterized groundwater model in an inverse calibration to estimate model parameters that best fit the observations.

Current (2010) and future (2030) conditions were simulated in the calibrated model to characterize the groundwater flow system and to determine potential effects of increased groundwater withdrawals on advective-transport patterns at the JBCC. Groundwater flow and advective transport are radially outward from a water-table divide in the northern part of the JBCC; flow diverges from the divide toward all points of the compass. Most groundwater flow and contaminant transport occur in shallow parts of the aquifer. On average, about one-half of the groundwater flux occurs in the shallowest 20 percent of the saturated thickness; shallow flow is even more predominant near streams and lakes. Projected (2030) increases in groundwater withdrawals decrease water levels by a maximum of about 1.2 feet in the northern part of the JBCC; drawdowns exceeding 1 foot generally are limited to areas near the largest increases in withdrawals, such as in the northern part of the JBCC, near Long Pond in Falmouth, and in eastern Barnstable. Streamflow decreases average about 6 percent; the largest decreases are in areas with the largest drawdowns. Changes in hydraulic-gradient directions at the water table exceed 1 degree in about 13 percent of the aquifer, generally near groundwater divides where gradient magnitudes are small and near large groundwater withdrawals. Predictions of advective transport from randomly selected locations at the water table are similar for current (2010) and future (2030) groundwater withdrawals. The results indicate that projected increases in groundwater withdrawals affect water levels and streamflows, but effects on hydraulic gradients and advective transport at the JBCC likely are small.

Several underlying assumptions inherent in the model, including observations and weights used in the calibration, representation of local-scale heterogeneity, and simulation of the freshwater/saltwater interface, could affect model calibration and predictions; these assumptions were evaluated with alternative models and alternative inverse calibrations. Eight alternative calibrations were performed in which different, but reasonable, observations and weights were used. The preferred calibrated model had the best overall fit to the observations.

Fine-grained silty sediments occur in many parts of the aquifer, and silt lenses can locally affect hydraulic gradients. A set of alternative models in which silts were represented with different correlation distances and hydraulic conductivities indicated that explicitly representing silt lenses could affect model calibration but that the implicit representation of local-scale heterogeneity may be sufficient at the regional scale to represent regional-scale hydraulic gradients. For the coastal boundary, two alternative models representing silty and sandy seabeds and their associated interface positions were developed to test the importance of the assumed coastal-boundary condition. The two alternative models resulted in different predictions of streamflow—streamflows increase with smaller (silty) seabed leakances. However, predictions of advective transport, particularly near the JBCC, generally were similar between the alternative and preferred calibrated models, indicating that the seabed leakance and associated interface position at the coastal boundary does not affect simulations of advective transport in inland parts of the aquifer.

Groundwater-Level Elevations in the Denver Basin Bedrock Aquifers of Elbert County, Colorado, 2015–18

Released April 18, 2019 12:40 EST

2019, Scientific Investigations Report 2019-5014

Colin A. Penn, Rhett R. Everett

Public and domestic water supplies in Elbert County, Colorado, rely on groundwater withdrawals from five bedrock aquifers in the Denver Basin aquifer system (lower Dawson, upper Dawson, Denver, Arapahoe, and Laramie-Fox Hills) to meet water demands. Increased pumping in response to regional population growth and development has led to declining groundwater levels in neighboring Douglas County. The U.S. Geological Survey, in cooperation with the Elbert County Board of County Commissioners, began a study in 2015 to monitor groundwater levels within Elbert County. The purpose of this study is to report on groundwater levels measured between April 2015 and June 2018, and analyze trends and changes in groundwater-level elevations throughout the county.

Discrete groundwater levels were measured at 42 wells within Elbert County. Six of those wells contained equipment to make and record continuous groundwater-level measurements at hourly intervals. All five aquifers had wells with a rise in groundwater-level elevation and wells with a decline in groundwater-level elevation, based on a relative change in groundwater-level elevation between the April 2015 and April 2018 measurements. All aquifers except the upper Dawson had more wells with significant negative trends in discrete groundwater-level elevations than significant positive trends; however, at least one well within the upper Dawson, lower Dawson, Arapahoe, and Laramie-Fox Hills aquifers had a significant positive trend. Wells screened in the lower Dawson aquifer consistently had the most significant negative trends, with an average trend of −1.96 feet per year (ft/year). The upper Dawson, Denver, Arapahoe, and Laramie-Fox Hills aquifers had average trends of 0.03 ft/year, −1.04 ft/year, −0.46 ft/year, and −0.65 ft/year, respectively. Trends in continuous groundwater-level elevations were in agreement with significant trends in discrete groundwater-level elevations. Potentiometric-surface maps of the upper and lower Dawson aquifers for April 2015 and April 2018 show that differences in hydraulic head from the two measurement periods were greatest along the western part of Elbert County. Results of this study could guide future groundwater monitoring in the county and aid in long-term planning of water resources.

Drought Forecasting for Streams and Groundwaters in Northeastern United States

Released April 17, 2019 14:00 EST

2019, Fact Sheet 2019-3015

Samuel H. Austin, Robert W. Dudley

Background

When rainfall is lower than normal over an extended period, streamflows decline, groundwater levels fall, and hydrological drought can occur. Droughts can reduce the water available for societal needs, such as public and private drinking-water supplies, farming, and industry, and for ecological health, such as maintenance of water quality and natural ecosystems. Recent droughts in the northeastern United States have highlighted the need for new scientific tools to forecast the probability of future droughts so water managers and the public can be better prepared for these events when they happen. Two recent U.S. Geological Survey (USGS) studies provide tools that can forecast the probabilities of summer droughts for streams and the probabilities of groundwater-level declines below specified targets or thresholds. These tools provide promising methods for identifying and anticipating probable streamflow and groundwater droughts specific to the northeastern United States. USGS Water Science Centers in the northeastern United States have acted together to use these methods for numerous streamflow gages and groundwater-level monitoring wells, and to make the results of the analyses available on the world wide web. This fact sheet describes the drought forecasting techniques used in a study to predict droughts for streamflow and groundwater in the northeastern United States.

Water-level data for the Albuquerque Basin and adjacent areas, central New Mexico, period of record through September 30, 2017

Released April 16, 2019 12:52 EST

2019, Data Series 1113

Joseph E. Beman, Andre B. Ritchie, Amy E. Galanter

The Albuquerque Basin, located in central New Mexico, is about 100 miles long and 25–40 miles wide. The basin is hydrologically defined as the extent of consolidated and unconsolidated deposits of Tertiary and Quaternary age that encompasses the structural Rio Grande Rift between San Acacia to the south and Cochiti Lake to the north. A 20-percent population increase in the basin from 1990 to 2000 and a 22-percent population increase from 2000 to 2010 resulted in an increased demand for water in areas within the basin. Drinking-water supplies throughout the basin were obtained solely from groundwater resources until December 2008, when the Albuquerque Bernalillo County Water Utility Authority (ABCWUA) began treatment and distribution of surface water from the Rio Grande through the San Juan-Chama Drinking Water Project.

An initial network of wells was established by the U.S. Geological Survey (USGS) in cooperation with the City of Albuquerque from April 1982 through September 1983 to monitor changes in groundwater levels throughout the Albuquerque Basin. In 1983, this network consisted of 6 wells with analog-to-digital recorders and 27 wells where water levels were measured monthly. The network currently (2017) consists of 122 wells and piezometers. (A piezometer is a specialized well open to a specific depth in the aquifer, often of small diameter and nested with other piezometers open to different depths.) The USGS, in cooperation with the ABCWUA and the New Mexico Office of the State Engineer, currently (2017) measures and reports water levels from the 122 wells and piezometers in the network; this report presents water-level data collected by USGS personnel at those 122 sites through water years 2016 and 2017 (October 1, 2015, through September 30, 2017). Water levels that were collected from wells in previous water years were published in previous USGS reports.

Monitoring storm tide and flooding from Hurricane Irma along the U.S. Virgin Islands, Puerto Rico, and the Southeastern United States, September 2017

Released April 16, 2019 08:13 EST

2019, Open-File Report 2019-1013

Michael J. Byrne, Sr., Mark R. Dickman

Hurricane Irma skirted the northern coasts of the U.S. Virgin Islands and Puerto Rico, with maximum sustained winds of 185 miles per hour (mi/h) on September 6, 2017. The hurricane first made landfall in Florida near Cudjoe Key, in the lower Florida Keys, with maximum sustained winds of 130 mi/h on September 10, 2017. The hurricane made a second Florida landfall on Marco Island, Florida, with maximum sustained winds of 115 mi/h on September 19, 2017. The U.S. Geological Survey (USGS), in cooperation with Federal Emergency Management Agency, deployed a temporary monitoring network of storm-surge and barometric pressure sensors at 249 locations along the Puerto Rico, Florida, Georgia, and South Carolina coasts to record the timing, areal extent, and magnitude of hurricane storm tide and coastal flooding generated by the hurricane. Immediately following the passage of Hurricane Irma, the sensors were retrieved, and the data were disseminated on the USGS Flood Event Viewer (https://stn.wim.usgs.gov/FEV/#IrmaSeptember2017). The storm-tide peak data values were verified by comparing data from hydrologic recorders and nearby high-water marks (HWMs). Following the hurricane, 508 independent HWM locations were flagged and surveyed relative to the North American Vertical Datum of 1988, National Geodetic Vertical Datum of 1929, or a local datum along the southeastern U.S. coast, and to Puerto Rico Vertical Datum of 2002 in Puerto Rico. Most HWMs were in Florida because of the path of the hurricane. The data from the Hurricane Irma storm-tide network are available on a provisional basis in tab-delimited, American Standard Code for Information Interchange (ASCII) format and Network Common Data Form (NetCDF) format by site for each sensor by using the USGS Flood Event Viewer.

Assessment of Mesozoic tight-oil and tight-gas resources in the Sichuan Basin of China, 2018

Released April 15, 2019 15:42 EST

2019, Fact Sheet 2019-3010

Christopher J. Potter, Christopher J. Schenk, Tracey J. Mercier, Marilyn E. Tennyson, Thomas M. Finn, Cheryl A. Woodall, Heidi M. Leathers-Miller, Kristen R. Marra, Phuong A. Le, Ronald M. Drake II, Michael E. Brownfield, Janet K. Pitman

Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 1.2 billion barrels of tight oil and 29.1 trillion cubic feet of tight gas in Mesozoic formations in the Sichuan Basin of China.

Morphology and molecular data reveal invasion of cryptic golden tegus Tupinambis cryptus Murphy et al., 2016) in Florida

Released April 15, 2019 15:39 EST

2019, BioInvasions Records

R. Alexander Pyron, Robert Reed, Timothy J. Colston, Michael R. Rochford

Golden Tegus (Tupinambis teguixin sensu lato) are native to South America and have established a reproducing population in Miami-Dade County, Florida. Recent work divided the Golden Tegu into four separate species, leaving the specific identity of Golden Tegus in Florida unknown. We used morphometric and mitochondrial data to determine the species identity and likely area of geographic origin for a specimen of Golden Tegu collected in Miami-Dade County, Florida. Our results indicate Cryptic Golden Tegus (Tupinambis cryptus) are the species established in Florida. Geographic origin is likely mainland Guyana or Venezuela.

Alaska Shorebird Conservation Plan, Version III

Released April 15, 2019 09:50 EST

2019, Book

Daniel R. Ruthrauff

In recognition of declines among perhaps half of Alaska’s breeding shorebirds, ongoing or emerging threats to shorebirds and their habitats, and considerable knowledge of Alaska’s shorebirds acquired over the past decade, the Alaska Shorebird Group decided that the Alaska Shorebird Conservation Plan was due for updates. Similar to Version II (2008), we structured the plan in two parts: Part I identifies Alaska’s nearly 30 priority species, their conservation threats, and strategies / objectives to improve statewide conservation, and Part II considers these three elements for Alaska’s five Bird Conservation Regions (as well as many specific actions). In addition to special recognition paid to species of greatest and high conservation concern, we included “Stewardship” species, defined as those species for which Alaska supports at least half of a population during its annual cycle. Climate change and severe weather, pollution, and energy- and mining-related activities ranked highest among conservation concerns in Alaska. Supplementing our tools for implementing conservation (research, inventory/monitoring, habitat management/protection, education/outreach, international collaboration), we introduced an evaluation of conservation progress to increase accountability. Based on considerable advances in tracking technologies largely unavailable prior to Version II, this plan stresses conservation approaches that recognize species’ full annual cycles. annual cycles.

Three-dimensional partitioning of resources by congeneric forest predators with recent sympatry

Released April 15, 2019 08:13 EST

2019, Scientific Reports (9) 1-10

Julianna M Jenkins, Damon B. Lesmeister, David Wiens, Jonathan T Kane, Van R. Kane, Jake V Verschuyl

Coexistence of ecologically similar species can be maintained by partitioning along one or more niche axes. Three-dimensional structural complexity is central to facilitating resource partitioning between many forest species, but is underrepresented in field-based studies. We examined resource selection by sympatric northern spotted owls (Strix occidentalis caurina), a threatened species under the US Endangered Species Act, and nonnative barred owls (S. varia) in western Oregon, USA to explore the relative importance of canopy heterogeneity, vertical complexity of forest, and abiotic features to resource selection and identify potential differences that may facilitate long-term coexistence. We predicted that within home range selection of understory densities, measured with airborne lidar, would differ between species based on proportional differences in arboreal and terrestrial prey taken by each owl species. We used discrete choice models and telemetry data from 41 spotted owls and 38 barred owls monitored during 2007–2009 and 2012–2015. Our results suggested that while both species used tall canopy areas more often than low canopy areas, spotted owls were more commonly found in areas with lower tree cover, more developed understory, and steeper slopes. This is the first evidence of fine-scale partitioning based on structural forest properties by northern spotted owls and barred owls.

Satellite tracking of gulls and genomic characterization of fecal bacteria reveals environmentally mediated acquisition and dispersal of antimicrobial resistant Escherichia coli on the Kenai Peninsula, Alaska

Released April 13, 2019 08:04 EST

2019, Molecular Ecology

Christina Ahlstrom, Jonas Bonnedahl, Hanna Woksepp, Jorge Hernandez, John Reed, Lee Tibbitts, Björn Olsen, David C. Douglas, Andrew M. Ramey

Gulls (Larus spp.) have frequently been reported to carry Escherichia coli exhibiting antimicrobial resistance (AMR E. coli); however, the pathways governing the acquisition and dispersal of such bacteria are not well-described. We equipped 17 landfill-foraging gulls with satellite transmitters and collected gull fecal samples longitudinally from four locations on the Kenai Peninsula, Alaska to assess: 1) gull attendance and transitions between sites, 2) spatiotemporal prevalence of fecally-shed AMR E. coli, and 3) genomic relatedness of AMR E. coli isolates among sites. We also sampled Pacific salmon (Oncorhynchus spp.) harvested as part of personal-use dipnet fisheries at two sites to assess potential contamination with AMR E. coli. Among our study sites, marked gulls most commonly occupied the lower Kenai River (61% of site locations) followed by the Soldotna landfill (11%), lower Kasilof River (5%), and upper Kenai River (<1%). Gulls primarily moved between the Soldotna landfill and the lower Kenai River (94% of transitions among sites), which were also the two locations with the highest prevalence of AMR E. coli. There was relatively high spatial and temporal variability in AMR E. coli prevalence in gull feces and there was no evidence of contamination on salmon harvested in personal-use fisheries. We identified E. coli sequence types and AMR genes of clinical importance, with some isolates possessing genes associated with resistance to as many as eight antibiotic classes. Our findings suggest that gulls acquire AMR E. coli at habitats with anthropogenic inputs and subsequent movements may represent pathways through which AMR is dispersed.

Can multi-element fingerprinting of soils inform assessments of chemical connectivity between depressional wetlands?

Released April 12, 2019 16:24 EST

2019, Wetlands

Xiaoyan Zhu, Yuxiang Yuan, David M. Mushet, Marinus L. Otte

The question of wetland connectivity is particularly relevant regarding depressional wetlands because these wetlands often seem to be “isolated” from other wetlands on a landscape. In this study, multi-element fingerprinting of soils was used to assess similarity in element composition of depressional-wetland soils as a measure of wetland connectivity. We determined the concentrations of 63 elements in the surface soil (top 10 cm) for ten sequences, each consisting of at least one recharge, one flow-through and one discharge depressional wetland in the Prairie Pothole Region of North Dakota. Across all wetlands, soil pH, organic matter content, and electrical conductivity were the most important variables explaining variation in element concentrations. Electrical conductivity and pH significantly increased along a recharge to flow-through to discharge gradient, as did concentrations of As, B, Ca, Co, Hf, Li, Mg, Na, S, Sb, and Sr. Concentrations of Ag, Cd, Cu, P, Pb, Rb, and Se showed the reverse pattern. Similarity-tree analysis revealed that recharge and discharge wetlands clustered in different groups, but that flow-through wetlands were distributed across the spectrum. Our study supports the idea that wetlands in the PPR are chemically connected through surface-water and groundwater flows, and erosional processes, but also behave as independent units within a larger hydrologic landscape.

Stratigraphic and structural relations in trench exposures and geomorphology at the Big Burn, Lily Lake, and Lester Ranch sites, Bear River Fault Zone, Utah and Wyoming

Released April 12, 2019 10:57 EST

2019, Scientific Investigations Map 3430

Suzanne Hecker, Christopher Duross, David P. Schwartz, Francesca R. Cinti, Riccardo Civico, William R. Lund, Adam I. Hiscock, Michael W. West, Tarka Wilcox, Alivia R. Stoller

This report provides trench photomosaics, logs and related site information, age data, and earthquake event evidence from three paleoseismic trench sites on the Bear River Fault Zone. Our motivation for studying the Bear River Fault Zone—a nascent normal fault in the Rocky Mountains east of the Basin and Range physiographic province—is twofold: (1) the intriguing conclusion from previous work that the neotectonic history of the fault may have begun in the middle to late Holocene and consists of only two surface-rupturing earthquakes and (2) the question of whether large scarps (>10 meters in height) observed along the fault represent net tectonic displacement, which, given a two-event history, would put the displacements among the largest in the Basin and Range region. In presenting our trench and initial geomorphic interpretations, this report lays the groundwork for further exploration of these issues.

Advancing barrier island habitat mapping using landscape position information

Released April 11, 2019 13:59 EST

2019, Progress in Physical Geography: Earth and Environment

Nicholas Enwright, Lei Wang, Sinéad M. Borchert, Richard Day, Laura Feher, Michael Osland

Barrier islands are dynamic ecosystems that change gradually from coastal processes, including currents and tides, and rapidly from episodic events, such as storms. These islands provide many important ecosystem services, including storm protection and erosion control to the mainland, habitat for fish and wildlife, and tourism. Habitat maps, developed by scientists, provide a critical tool for monitoring changes to these dynamic ecosystems. Barrier island monitoring often requires custom habitat maps due to several factors, including island size and the classification of unique geomorphology-based habitats, such as beach, dune, and barrier flats. In this study, we reviewed barrier-island-specific habitat mapping efforts and highlighted common habitat class types, source data, and mapping approaches. We also developed a framework for mapping geomorphology-based barrier island habitats using a rule-based, geographic object-based image analysis approach, which included the use of field data, tide data, high-resolution orthophotography, and lidar data. This framework integrates several barrier island mapping advancements with regard to the use of landscape position information for automated dune extraction and the use of Monte Carlo analyses for the treatment of elevation uncertainty for elevation-dependent habitats. Specifically, we used the uncertainty analyses to refine automated dune delineation based on elevation relative to extreme storm water levels and to increase the accuracy of intertidal and supratidal/upland habitat delineation. We found that dune extraction results were enhanced when elevation relative to storm water levels and visual interpretation were also applied. This framework could also be applied to beach–dune systems found along a mainland.

Three-dimensional basin and fault structure from a detailed seismic velocity model of Coachella Valley, Southern California

Released April 11, 2019 09:50 EST

2019, Journal of Geophysical Research

Rasheed Ajala, Patricia Persaud, Joann M. Stock, Gary S. Fuis, John A. Hole, Mark Goldman, Daniel Scheirer

The Coachella Valley in the northern Salton Trough is known to produce destructive earthquakes, making it a high seismic hazard area. Knowledge of the seismic velocity structure and geometry of the sedimentary basins and fault zones is required to improve earthquake hazard estimates in this region. We simultaneously inverted first P wave travel times from the Southern California Seismic Network (39,998 local earthquakes) and explosions (251 land/sea shots) from the 2011 Salton Seismic Imaging Project to obtain a 3-D seismic velocity model. Earthquakes with focal depths ≤10 km were selected to focus on the upper crustal structure. Strong lateral velocity contrasts in the top ~3 km correlate well with the surface geology, including the low-velocity (<5 km/s) sedimentary basin and the high-velocity crystalline basement rocks outside the valley. Sediment thickness is ~4 km in the southeastern valley near the Salton Sea and decreases to <2 km at the northwestern end of the valley. Eastward thickening of sediments toward the San Andreas fault within the valley defines Coachella Valley basin asymmetry. In the Peninsular Ranges, zones of relatively high seismic velocities (~6.4 km/s) between 2 to 4 km depth may be related to Late Cretaceous mylonite rocks or older inherited basement structures. Other high-velocity domains exist in the model down to 9 km depth and help define crustal heterogeneity. We identify a potential fault zone in Lost Horse Valley unassociated with mapped faults in Southern California from the combined interpretation of surface geology, seismicity, and lateral velocity changes in the model.

To forage or flee: Lessons from an elk migration near a protected area

Released April 11, 2019 08:55 EST

2019, Ecosphere (10) 1-15

Nathaniel Mikle, Tabitha A. Graves, Edward M. Olexa

Alteration of wide-ranging wildlife migrations can drastically impact the structure and function of ecosystems, yet the causes and consequences of shifting migration patterns remain largely unknown. Management decisions made in one portion of a landscape may induce spatial and temporal shifts of wildlife use in another, creating tension among private, state, and federal lands with varying missions. Recent declines in migratory behavior have initiated studies focused primarily on spring migration, but the timing and benefits of autumn migration have received limited attention due to the difficulty in assessing the extreme asynchrony in autumnal events, although nutrition during this time period is crucial to winter survival and reproduction. Here, we used five years of data from 73 female elk (Cervus canadensis) which utilize a landscape managed by 4 federal agencies, a state, and private landowners, to identify the driving factors behind the initiation of fall migration in two subpopulations, one of which migrates to a protected area where hunting is prohibited. Most elk departed summer range prior to frost or snow, with 67% of elk that used the protected area migrating prior to the onset of archery hunting season (1 September), preemptively avoiding risk, while no elk from the other subpopulation left prior to archery season. However, departure from productive summer range prior to frost or snow, nearly two months before vegetation senescence led to an important tradeoff. Early migrants gave up 0.30% of late summer-fall integrated NDVI (iNDVI) per day when they moved to the safety of the protected area, leading to an average difference of 15.81% in iNDVI between an individual departing on 30 August (the mean departure date) versus an individual departing on 1 November. Our results suggest that in areas where migratory ungulates span multiple jurisdictions, the benefits of migratory behavior may be dramatically impacted by unevenly distributed anthropogenic disturbance. As this is a common scenario globally, our work highlights the urgent need to improve our understanding of subtle changes in migratory behavior, both spatially and temporally, which may erode the resilience of migration to future change.

Rare earth element mineral deposits in the United States

Released April 11, 2019 06:43 EST

2019, Circular 1454

Bradley S. Van Gosen, Philip L. Verplanck, Poul Emsbo

Because of their unique special chemical properties, many of the metals in the group of rare earth elements (REEs) have essential applications in 21st century technologies. Examples of products that use REEs are cell phones, computers, fluorescent and light-emitting-diode lights, flat-screen television and computer monitors, and in high-strength magnets used by clean energy technologies such as the generators of wind turbines and batteries of hybrid and electric vehicles. REEs are used in many defense applications, such as in components of jet engines, missile guidance systems, antimissile defense systems, satellites, and communication systems.

The rare earth elements have become vital to manufacturing numerous high-tech products, which has been accompanied by a large increase in their demand. At the same time, there has been concern by the United States and many other Nations about the near-monopoly of mining, processing, and supply of REEs from one Nation, China. Between 2011 and 2017, China produced approximately 84 percent of the world’s REEs, and during this time the United States only produced REEs between 2012 and 2015. The U.S. production came entirely from the Mountain Pass mine in California, providing only about 4 percent of the world REE supply. Because REEs are essential for technological applications and are primarily supplied by one Nation, there has been an increased concern in identifying new sources of REEs, including economic REE deposits.

In response to these concerns, since 2009, the U.S. Geological Survey (USGS) has conducted numerous studies focused on the distribution, geology, and potential resources for the REE-bearing mineral deposits in the United States. The basic characteristics of mineral deposit types that host REE enrichments in the United Sates are summarized in this report, with selected examples. Several types of REE-enriched mineral deposits are reviewed, including deposits in carbonatites, alkaline igneous rocks, sedimentary phosphate-rich rocks (phosphorite), regions containing REE-rich veins, iron oxide deposits containing REE-bearing apatite, monazite-xenotime-bearing placer deposits (heavy-mineral sands), and ion-adsorption clay deposits (REE in granite-derived regolith). A better understanding of these mineral deposits will assist in identifying domestic resources to help alleviate the dependence on imported REEs.

The economic development of REE mineral deposits is affected by many factors beyond mining, such as commodity prices and mineral processing costs. Most of the REEs are hosted by minerals that have complex chemical formulas; this presents more challenges to process and extract the REEs. Continued advancements and refinements in mineral processing techniques may allow REE deposits with complex mineralogy to be economically developed in the future.

Spatial and Temporal Patterns of Best Management Practice Implementation in the Chesapeake Bay Watershed, 1985–2014

Released April 10, 2019 15:00 EST

2019, Scientific Investigations Report 2018-5171

Andrew J. Sekellick, Olivia H. Devereux, Jennifer L.D. Keisman, Jeffrey S. Sweeney, Joel D. Blomquist

Efforts to restore water quality in Chesapeake Bay and its tributaries often include extensive Best Management Practice (BMP) implementation on agricultural and developed lands. These BMPs include a variety of methods to reduce nutrient and sediment loads, such as cover crops, conservation tillage, urban filtering systems, and other practices.

Estimates of BMP implementation throughout the Chesapeake Bay watershed were provided for each year from 1985 through 2014 by the Chesapeake Bay Program (CBP). This dataset of BMP implementation is a compilation of actions reported by New York, Maryland, Pennsylvania, Delaware, West Virginia, Virginia, and the District of Columbia, and includes a wide array of management activities. Management actions vary among the jurisdictions and generally reflect the typical land use in each region.

The amount of implementation also varies according to different priorities, reporting practices, and special programs within each jurisdiction. For example, extensive cover crop implementation was reported in Maryland whereas Pennsylvania, in general, has lower levels of BMP implementation reported on cropland. Pennsylvania and Maryland have higher levels of infiltration BMPs on developed land compared to those in Virginia.

Conservation tillage BMPs accounted for the majority of reported agricultural BMP implementation in 1985. By 2014, however, a more diverse collection of agricultural BMPs was reported and conservation tillage BMPs accounted for a smaller proportion of overall reported agricultural BMP implementation. After the year 2000, land-use change BMPs, such as land retirement, pasture fencing, and forest buffers, were more commonly reported across the Chesapeake Bay watershed.

Expected changes in nutrient and sediment loads in the Chesapeake Bay watershed due to BMP implementation were estimated by use of specially designed annual scenarios of the CBP Partnership Phase 5.3.2 Watershed Model. Nitrogen loads to streams were estimated to be reduced by 11 percent from 1985 to 2014 due to the implementation of BMPs. Compared with 1985, phosphorus loads were estimated to be 19 percent lower and sediment loads were estimated to be 23 percent lower by 2014 due to the effects of BMPs.

Reductions in total nitrogen from 1985 to 2014 due to BMPs varied spatially across the watershed and were estimated to be as high as 42 percent in areas of the Eastern Shore of the Chesapeake Bay. Reductions in phosphorus and sediment also varied spatially, with the largest reductions occurring in the Potomac watershed upstream of Washington, D.C. and the Eastern Shore of Maryland, according to the CBP model results.

Additional model scenarios were developed to estimate the effect of individual BMP types. The largest estimated reductions in total nitrogen loads on agricultural lands in 2014 were attributed to land retirement, animal waste management systems, and conservation tillage. The largest estimated reductions in total phosphorus loads on agricultural lands were attributed to animal waste management systems, pasture fencing, and phytase feed additives in 2014. The largest estimated reduction in total sediment loads on agricultural lands was attributed to conservation tillage, pasture fencing, and conservation plans.

Dry ponds, wet ponds, and constructed wetlands were reported extensively throughout the watershed. These BMPs accounted for about half of the reduction in nitrogen loads from developed land to streams, half of the phosphorus reduction, and about a third of the sediment reduction.

Groundwater quality and nutrient trends near Marsing, southwestern Idaho, 2018

Released April 10, 2019 13:17 EST

2019, Open-File Report 2019-1032

Kenneth D. Skinner

The U.S. Geological Survey, in cooperation with the Idaho Department of Environmental Quality, sampled groundwater from 15 wells during spring 2018 near the city of Marsing in rural northwestern Owyhee County, southwestern Idaho. Samples were analyzed for field parameters, nutrients, trace elements, major inorganics, and dissolved gas, including methane. To examine trends in individual wells and in the region, ammonia and nitrate results from the spring 2018 sampling were compared with data collected from 1996 to 2015 by the Idaho Department of Environmental Quality and the Idaho State Department of Agriculture.

Fourteen of the 15 samples collected in 2018 contained arsenic (0.13–33.8 micrograms per liter [μg/L]), with 7 arsenic concentrations greater than the U.S. Environmental Protection Agency (EPA) maximum contaminant level (MCL) of 10 μg/L. Iron (465–4,180 μg/L), manganese (54–693 μg/L), sulfate (300–624 milligrams per liter [mg/L]), and total dissolved solids (511–1,350 mg/L) were detected at concentrations greater than EPA secondary maximum contaminant levels (SMCL) in water-quality samples from 6, 10, 4, and 14 of the 15 wells, respectively. Fourteen of the 15 samples contained ammonia concentrations from 0.12 to 7.34 milligrams per liter (mg/L). Six samples contained nitrate concentrations from 0.08 to 24.6 mg/L, with one sample greater than the EPA MCL of 10 mg/L for drinking water. The presence of both ammonia and nitrate in four samples indicated multiple nutrient and groundwater sources and varying redox states. Ammonia concentrations tended to increase downgradient throughout the study area.

Nutrient trend analysis identified water-quality samples from 2 of the 15 wells with increasing nitrate concentrations from 1999–2018 and 2005–2018. The well with increasing nitrate concentrations from 2005–2018 showed a decreasing trend in ammonia concentrations during the same time period. Groundwater-quality samples from the 13 remaining wells showed no temporal trends. A Regional Kendall test, which evaluates trends at numerous wells across the study area to determine if a consistent trend exists for the area, was done to analyze 539 ammonia concentrations from 91 wells over 20 years (1999–2018) and 591 nitrate concentrations from 107 wells over 23 years (1996–2018). The Regional Kendall Test for ammonia had a tau correlation coefficient of -0.073 with a p-value of 0.072, and nitrate had a tau correlation coefficient of -0.041 with a p-value of 0.198, both indicating no statistically significant trends.

A landscape model of variable social-ecological fire regimes

Released April 10, 2019 10:09 EST

2019, Ecological Modelling (401) 85-93

Robert M Scheller, Alec Kretchun, Todd Hawbaker, Paul D. Henne

Fire regimes are now recognized as the product of social processes whereby fire on any landscape is the product of human-generated drivers: climate change, historical patterns of vegetation manipulation, invasive species, active fire suppression, ongoing fuel management efforts, prescribed burning, and accidental ignitions. We developed a new fire model (Social-Climate Related Pyrogenic Processes and their Landscape Effects: SCRPPLE) that emphasizes the social dimensions of fire and enables simulation of fuel-treatment effects, fire suppression, and prescribed fires. Fire behavior was parameterized with daily fire weather, ignition, and fire-boundary data. SCRPPLE was initially parameterized and developed for the Lake Tahoe Basin (LTB) in California and Nevada, USA although its behavior is general and could be applied worldwide. We demonstrate the behavior and utility of our model via four simple scenarios that emphasize the social dimensions of fire regimes: a) Recent Historical: simulated recent historical patterns of lightning and accidental fires and current patterns of fire suppression, b) Natural-Fire-Regime: simulated wildfire without suppression, accidental fires, or prescribed fires, holding all other factors the same as Recent Historical, c) Enhanced Suppression: simulated a doubling of the effectiveness of suppression, holding all other factors the same as Recent Historical, and d) Reduced Accidental Ignitions: within which the number of accidental fires was reduced by half, holding all other factors the same as Recent Historical. Results indicate that SCRPPLE can recreate past fire regimes, including size, intensity, and locations. Furthermore, our results indicate that the ‘Enhanced Suppression’ and ‘Reduced Accidental Ignitions’ scenarios had similar capacity to reduce fire and related tree mortality over time, suggesting that within the broad outlines of the scenarios, reducing accidental fires can be as effective as substantially increasing resources for suppression.

Hurricane Sandy impacts on coastal wetland resilience

Released April 10, 2019 08:15 EST

2019, Open-File Report 2018-1142

Donald R. Cahoon, Jennifer H. Olker, Alice G. Yeates, Glenn R. Guntenspergen, James B. Grace, Susan C. Adamowicz, Shimon C. Anisfeld, Andrew H. Baldwin, Nels Barrett, Leah Beckett, Alice Benzecry, Linda K. Blum, David M. Burdick, William Crouch, Marci Cole Ekberg, Sarah Fernald, Kristin Wilson Grimes, Joseph Grzyb, Ellen Kracauer Hartig, Danielle A. Kreeger, Marit Larson, Scott Lerberg, James C. Lynch, Nicole Maher, Martha Maxwell-Doyle, Laura R. Mitchell, Jordan Mora, Victoria O'Neill, Angela Padeletti, Diann J. Prosser, Tracy Quirk, Kenneth B. Raposa, William G. Reay, Drexel Siok, Christopher Snow, Adam Starke, J. Court Stevenson, Lorie Staver, Vincent Turner

The goal of this research was to evaluate the impacts of Hurricane Sandy on surface elevation trends in estuarine marshes located across the northeast region of the United States from Virginia to Maine using data from an opportunistic (in other words, not strategic) and collaborative network (from here on, an opportunistic network) of surface elevation table-marker horizon (SET-MH) stations. First, we built a data-base of metadata for 965 individual stations from 96 unique geographical locations that included the location, geomorphic setting, and wetland type for each SET-MH station. The dominant estuarine settings included in the analyses were back-barrier lagoonal marshes and emergent marshes along embayments and tidal tributaries. We then calculated prestorm elevation trends to compare to poststorm elevation measurements to determine the storm impact on each station trend. We hypothesized that the effect of Hurricane Sandy on marsh elevation trends would differ by position relative to landfall (right or left) and distance from landfall in southern New Jersey, as both of these variables influence the presence or absence of storm surge as a result of the physical characteristics of tropical cyclones (in other words, strongest winds typically occur to the right of landfall). Storm surge was spatially less extensive and less deep (~1 meter [m]) in marshes located to the left (in other words, south) of landfall compared to marshes located to the right (in other words, north) of landfall where storm surge covered a larger area and was deeper (3–4 m). About 63 percent of 223 eligible stations had a poststorm trend that was similar to the prestorm trend (in other words, less than ±5 millimeters [mm]), indicating little storm impact on elevation trends at those sites. The remaining 37 percent of stations exhibited significant poststorm deviations from the prestorm trend (in other words, greater than ±5 mm). Of these, stations located to the left of landfall had a significant and greater deviation in their elevation trend, and the deviation was more likely to be positive (elevation gain) compared to marshes located to the right of landfall, which had a significant deviation in their elevation trend that was more likely to be negative (elevation loss). This finding is directly related to storm surge impacts on marsh sediment deposition, where deep storm surge (3–4 m) results in sediment deposition in habitats inland of coastal marshes but less so in the marshes themselves. Substrate compaction by the storm surge over-burden may have contributed to elevation loss, but this was not measured because sufficient marker horizon data were not available for analysis. In contrast, to the left of landfall the wind-driven flooding of sediment laden water pushed into the headwaters of rivers and small bays with an ~1 m surge, and resulted in more prevalent sediment deposition on the marsh surfaces and elevation gain. In general, the findings support previous research showing that the physical characteristics of the storm (for example, wind speed, storm surge height, impact angle of landfall) combined with the local wetland conditions (for example, marsh productivity, groundwater level, tide height) are important factors determining a storm’s impact on soil elevation, and that the soil elevation response can vary widely among multiple wetland sites impacted by the same storm and among different storms for the same wetland site.

The final objective of this project was to create a framework using metadata from the opportunistic network of SET-MH stations that could be used to develop a strategic monitoring network designed to address specific climate change impacts and related phenomena identified by land managers and stakeholders. We evaluated the spatial distribution and density of SET-MH stations in relation to geographic coverage, marsh setting, availability of public land, and historical storm surge footprints and hurricane return intervals in order to identify gaps in our understanding of risk and our ability to assess it. Analyses revealed that the general geographic coverage of SET-MH stations is limited given the low percentage of marsh patches with stations, low density of stations, the clumped distribution of stations, and the often limited and uneven distribution of stations in wetlands with a high historical frequency of hurricane strikes and storm surge impacts. These findings can be used by managers and planners to inform the creation of a strategic monitoring network that can, in turn, inform management and adaptation plans for coastal resources in the region. Final plan designs will need to consider financial and infrastructural support required for station maintenance, as well as data collection and management over the long term.

Annual survival, site fidelity, and longevity in the eastern coastal population of the Painted Bunting (Passerina ciris) based on a 20-year mark-recapture/resighting study

Released April 09, 2019 16:27 EST

2019, Wilson Journal of Ornithology (131) 96-110

Paul W. Jr Sykes, Mary C. Freeman, Joan J. Sykes, John T. Seginak, M. David Oleyar, Joshua P. Egan

A long-term study of annual survival, longevity, and site fidelity in the eastern coastal population of the Painted Bunting (Passerina ciris) during the breeding season was conducted from 1999 through 2018 in the outer coastal plain of the southeastern Atlantic coast of the United States. Painted Buntings were uniquely color-banded from 1999 through 2003 at 40 study sites that were paired at 20 locations from southeastern North Carolina south to northeastern Florida. Survival analysis used capture histories through 2005 for 994 birds banded as hatch-year and 2420 birds banded as post-hatch-year (adults). Annual estimates of apparent survival (1999-2004) averaged 0.71 and 0.66 for adult males and females, respectively, and 0.33 for hatch-year birds. We did not find evidence that survival differed in relation to latitude or extent of human development near study sites, although estimates for adult females were higher for birds banded on sheltered islands compared to the mainland. Expected time in the population, based on estimated survival, was 3.9 and 3.4 years for adult males and females, respectively. The oldest observed birds were a 14-year old male observed in June 2016 at Harris Neck NWR, Georgia, the site at which he had been banded in July 2003 as a second-year bird, and a 13-year old male seen at Ft. George Island, Florida in June 2016, 2 km across a tidal estuary from the site where the bird was banded in August 2003 as hatch-year. The males were sighted at these two sites in 9 and 11 different years, respectively. Overall, 78% (males) and 81% (females) of re-sightings and re-captures of birds banded as adults occurred at the same study site where individuals were banded, compared to 59% (males) and 60% (females) of birds banded as hatch-year. Known mortalities of banded buntings included nine birds trapped for the caged-bird trade. This study shows the potential for high survival and longevity in the eastern coastal population of the Painted Bunting, and given evidence of high site fidelity in the breeding range, the vulnerability of the population to human development along the southeastern U.S. coast as well as to illegal trapping.

Geologic cross section A–A′ through the Appalachian basin from the southern margin of the Ontario Lowlands province, Genesee County, western New York, to the Valley and Ridge province, Lycoming County, north-central Pennsylvania

Released April 09, 2019 14:15 EST

2019, Scientific Investigations Map 3425

Michael H. Trippi, Robert T. Ryder, Catherine B. Enomoto

Introduction

Geologic cross section A–A′  is the fifth in a series of cross sections constructed by the U.S. Geological Survey (USGS) to document and improve understand­ing of the geologic framework and petroleum systems of the Appalachian basin. Cross section A–A′ provides a regional view of the structural and stratigraphic frame­work of the Appalachian basin from the southern mar­gin of the Ontario Lowlands province in western New York, across the Allegheny Plateau province of central New York and north-central Pennsylvania, to the Valley and Ridge province in north-central Pennsylvania, a dis­tance of approximately 176 miles. This cross section is a companion to cross sections E–E′, D–D′, C–C′, and I–I′  that are located approximately 100 to 500 miles to the southwest. Cross section A–A′ complements earlier geologic or strati­graphic cross sections through the central New York and north-central Pennsylvania part of the Appalachian basin. Although some of these other cross sections show more structural and stratigraphic detail, they are of more limited extent geographically and stratigraphically.

Cross section A–A′ contains much information that is useful for evaluating energy resources in the Appalachian basin. Although the Appalachian basin petroleum systems are not shown on the cross section, many of their key elements (such as source rocks, reservoir rocks, seals, and traps) can be inferred from lithologic units, unconformities, and geologic structures shown on the cross section. Important oil- and gas-bearing formations like the Oriskany Sandstone, Medina Group sandstones, Tuscarora Sandstone, and the Marcellus and Utica Shales are present on cross-section A–A′.

Optimizing historical preservation under climate change—An overview of the optimal preservation model and pilot testing at Cape Lookout National Seashore

Released April 09, 2019 13:45 EST

2019, Open-File Report 2018-1180

Erin Seekamp, Max Post van der Burg, Sandra Fatorić, Mitchell J. Eaton, Xiao Xiao, Allie McCreary

Adapting cultural resources to climate-change effects challenges traditional cultural resource decision making because some adaptation strategies can negatively affect the integrity of cultural resources. Yet, the inevitability of climate-change effects—even given the uncertain timing of those effects—necessitates that managers begin prioritizing resources for climate-change adaptation. Prioritization imposes an additional management challenge: managers must make difficult tradeoffs to achieve desired management outcomes related to maximizing the resource values. This report provides an overview of a pilot effort to integrate vulnerability (exposure and sensitivity), significance, and use potential metrics in a decision framework—the Optimal Preservation (OptiPres) Model—to inform climate adaptation planning of a subset of buildings in historic districts (listed on the National Register of Historic Places) at Cape Lookout National Seashore. The OptiPres Model uses a numerical optimization algorithm to assess the timing and application of a portfolio of adaptation actions that could most effectively preserve an assortment of buildings associated with different histories, intended uses, and construction design and materials over a 30-year planning horizon. The outputs from the different budget scenarios, though not prescriptive, provide visualizations of and insights to the sequence and type of optimal actions and the changes to individual building resource values and accumulated resource values. Study findings suggest the OptiPres Model has planning utility related to fiscal efficiency by identifying a budget threshold necessary to maintain the historical significance and use potential of historical buildings while reducing vulnerability (collectively, the accumulated resource value). Specifically, findings identify that a minimum of the industry standard ($222,000 annually for the 17 buildings) is needed to maintain the current accumulated resource value. Additionally, results suggest that additional appropriations provided on regular intervals when annual appropriations are at the industry standard are nearly as efficient as annual appropriations at twice the rate of industry standards and increase the amount of accumulated resource values to nearly the same level. However, periodic increases in funding may increase the risks posed to buildings from the probability of a natural hazard (that is, damage or loss from a hurricane). Suggestions for model refinements include developing standardized cost estimations for adaptation actions based on square footage and building materials, developing metrics to quantify the historical integrity of buildings, integrating social values data, including additional objectives (such as public safety) in the model, refining vulnerability data and transforming the data to include risk assessment, and incorporating stochastic events (that is, hurricane and wind effects) into the model.

Multidecadal geomorphic evolution of a profoundly disturbed gravel-bed river system—a complex, nonlinear response and its impact on sediment delivery

Released April 08, 2019 15:06 EST

2019, Journal of Geophysical Research: Earth Surface

Jon J. Major, Shan Zheng, Adam Mosbrucker, Kurt R. Spicer, Tami Christianson, Colin R. Thorne

A 2.5-km3 debris avalanche during the 1980 eruption of Mount St. Helens reset the fluvial landscape of upper North Fork Toutle River valley. Since then, a new drainage network has formed and evolved. Cross-section surveys repeated over nearly 40 years at 16 locations along a 20-km reach of river valley document channel evolution, geomorphic processes, and their impacts on sediment delivery. We analyzed spatial and temporal changes in channel morphology using two new metrics: 1) a shape index that defines the degree of U-shaped or V-shaped valley geometry; and 2) an alluvial phase-space diagram that relates bed degradation or aggradation between consecutive surveys to increases or decreases in cross-section area. Metric relations reveal more diverse channel evolution than originally described by a simple, linear-response model of sequential channel initiation and incision; aggradation and widening; and subsequent episodic scour and fill with little change in bed elevation. Instead, vertical and lateral adjustments have been crucial processes intertwined throughout channel evolution. Channel evolution has followed a distinctly nonlinear and non-sequential trajectory, migrating through several phase spaces and involving varied combinations of (1) degradation and aggradation with widening and narrowing, (2) bed-level fluctuations with little change in cross-section area, and (3) changes in cross-section area with little change of bed elevation. Persistent channel widening and reworking of the channel bed presently drive elevated sediment delivery from this basin. Elevated sediment delivery is likely to persist until valley-floor widths greatly exceed that of the channel-migration corridor, and/or channel banks and valley walls stabilize.

Sediment storage and transport in the Nooksack River basin, northwestern Washington, 2006–15

Released April 08, 2019 11:07 EST

2019, Scientific Investigations Report 2019-5008

Scott W. Anderson, Christopher P. Konrad, Eric E. Grossman, Christopher A. Curran

The Nooksack River is a dynamic gravel-bedded river in northwestern Washington, draining off Mount Baker and the North Cascades into Puget Sound. Working in cooperation with Whatcom County Conservation District, the U.S. Geological Survey studied topographic, hydrologic, and climatic data for the Nooksack River basin to document recent changes in sediment storage, long-term bed elevation trends, rates of sediment transport, and factors influencing surficial drainage in order to support ongoing river management. Differences in elevations between topographic and bathymetric surveys in 2005/06 and 2013/15 indicate the active channel aggraded about 1–2 feet locally near the cities of Ferndale and Everson but was primarily stable between them. The active channel upstream of Nugent’s Corner generally incised. Total incision upstream of Nugent’s Corner to Glacier Creek generated 2.3 ± 1.7 million cubic yards of sediment from 2005/06 to 2013 and likely represented a significant source of coarse sediment to the lower mainstem river over that time.

Long-term records of local channel-bed elevation, derived from U.S. Geological Survey streamgage data, show bed-elevation changes of about 1–3 feet. The river bed at most streamgages exhibits long-term trends, with relatively consistent rates of change on the order of 1 foot per decade that persist years to decades. Lagged correlations in bed-elevation trends at all seven streamgages in the North Fork Nooksack and mainstem Nooksack suggest that decadal periods of persistent aggradation and incision originate in the North Fork and translate downstream. The channel-change signal propagates downstream 0.5–2.5 miles per year, with the rate of propagation scaling closely with channel slope. The pattern of incision and aggradation in the North Fork correlates with regional climate, where persistent incision follows extended cold and wet periods, and persistent aggradation follows extended warm and dry periods. Climate-driven variation in coarse-sediment delivery, primarily from the North Fork Nooksack, then appears to be a strong control on long-term vertical channel adjustments at sites downstream. The downstream-translating climate signal generated in the North Fork would account for recently observed aggradation at Everson and Ferndale but not the observed incision in unconfined reaches upstream of Nugent’s Corner from 2005–06 to 2013. This mismatch indicates that understanding how changes in sediment-supply influence those unconfined reaches remains a key uncertainty for predicting future channel change.

Continuous turbidity monitoring integrated with suspended sediment and limited bedload sampling were used to calculate annual sediment loads at five sites in the basin. The sediment load in the lower river at Ferndale ranged from 0.78 to 1.17 million tons per year and averaged 0.97 million tons per year for WYs 2012–17. Suspended sediment made up 93 percent of the load, and bedload made up 7 percent. Most of the fine sediment load of the lower river is supplied from headwaters of the North, Middle, and South Fork Nooksack basins, with relatively little net increase in fine sediment loads in the lower mainstem basin. The three forks supply approximately equal proportions of the lower-river fine sediment load. However, the glacially sourced North and Middle Fork Nooksack basins carry a notably sandier suspended-sediment load than the South Fork Nooksack.

A comparison of monthly streamflow and precipitation trends since 1981 indicate statistically significant increases in total spring precipitation and the number of spring days with measurable precipitation in much of the basin, as well as increases in mean spring river stage near Ferndale. Since no trends in mean spring discharge are observed, the trends in river stage are attributed primarily to observed changes in bed elevation. Changes in bed elevation and precipitation may then both have plausibly impacted field drainage in the lower river below Ferndale.

Implications of climate scenarios for Badlands National Park resource management

Released April 08, 2019 09:55 EST

2019, Report

Brian W. Miller, Amy Symstad, Gregor Schuurman

Badlands National Park (BADL) hosts a myriad of natural and cultural resources, including bison and black-footed ferrets, the mixed grass prairie they live in, 37-75 million-year-old fossils, and historic buildings, trails, and roads. All are sensitive to climate, but anticipating precisely how each will be affected by climate change is difficult. In the face of this challenge, park resource managers must nevertheless make forward-looking decisions and take action to meet resource management goals. Fortunately, tools exist to identify strategies and actions likely to succeed under a range of potential future climate conditions. Two such tools—qualitative scenario planning and quantitative ecological simulation modeling—were used to anticipate management challenges and identify solutions for BADL and adjacent federal and tribal lands in the coming decades (through 2050). This brief summarizes and synthesizes results of this work. Although the brief focuses on BADL, it also includes several key insights gained from examining management approaches on adjacent lands.

The Value of Data – The Qatar Geologic Mapping Project

Released April 08, 2019 09:44 EST

2019, Conference Paper, Geotechnical Special Publication

Joseph T. Krupansky, Michael A. Knight, Randall Orndorff, Khaled M. Al-Akhras, Ara G. Mouradian, Ali F. Saleh

The State of Qatar is in a period of rapid development, modernization, and population growth. One of the most important factors influencing the long-term success and sustainability of future development is a comprehensive understanding of the region’s geologic regime, geotechnical conditions, natural resources, and environmental constraints. To obtain this understanding, the Ministry of Municipality and Environment (MME) of the State of Qatar has undertaken the Qatar Geological Mapping Project (QGMP). The project was envisioned with the strategic foresight to compile and utilize existing and legacy subsurface data collected as part of its massive infrastructure and development projects as the foundation for developing modern scientific resources including geologic maps, digital thematic maps, and a 3-dimensional geological model of the Doha metropolitan area. Recently, the MME, in consultation with Gannett Fleming, Inc. (GF) and the United States Geological Survey (USGS) concluded the data collection and analysis phase (Phase I) of the two-phase QGMP. Phase I included: the development of a comprehensive geotechnical relational database populated with data digitized from more than 13,000 subsurface data logs; a detailed data quality analysis and distribution assessment; an extensive gap analysis and needs assessment; and careful design of the geologic mapping and subsurface investigation programs for the next phase of the project.

Quantifying hydrologic alteration in an area lacking current reference conditions—The Mississippi Alluvial Plain of the South-Central U.S.

Released April 08, 2019 09:05 EST

2019, River Research and Applications

Rheannon M. Hart, Brian Breaker

To better understand the effects of hydrologic alteration as they relate to human and biological needs within the Mississippi Alluvial Plain of the south-central United States, the quantification of hydrologic alteration is required. Quantifying hydrologic alteration in the Mississippi Alluvial Plain is particularly difficult because of the lack of current reference, or even relatively undisturbed, U.S. Geological Survey (USGS) streamflow-gaging stations. Water withdrawals for agriculture in the form of weirs, dams, channelization and other forms of regulation within the Mississippi Alluvial Plain increased substantially beginning around 1960 suggesting that streamflow is substantially altered after this time period. To overcome the lack of stations that exist in the present that are unaffected by anthropogenic activities (or current reference stations), historical streamflow data were used to estimate what streamflow would be in the present without anthropogenic influence (or current reference conditions). These data, when combined with current streamflow information collected by the USGS in south and eastern Arkansas, southwest corner Kentucky, Louisiana, western Mississippi, southeastern corner Missouri, extreme western Tennessee, and extreme southeastern Texas were used to assess the level of hydrologic alteration within the study area.

A stratigraphic approach to inferring depositional ages from detrital geochronology data

Released April 05, 2019 13:56 EST

2019, Frontiers in Earth Science (7)

Samuel A. Johnstone, Theresa M. Schwartz, Christopher S. Holm-Denoma

With the increasing use of detrital geochronology data for provenance analyses, we have also developed new constraints on the age of otherwise undateable sedimentary deposits. Because a deposit can be no older than its youngest mineral constituent, the youngest defensible detrital mineral age defines the maximum depositional age of the sampled bed. Defining the youngest `defensible' age in the face of uncertainty (e.g., analytical and geological uncertainty, or sample contamination) is challenging. The current standard practice of finding multiple detrital minerals with indistinguishable ages provides confidence that a given age is not an artifact; however, we show how requiring this overlap reduces the probability of identifying the true youngest component age. Barring unusual complications, the principle of superposition dictates that sedimentary deposits must get younger upsection. This fundamental constraint can be incoporated into the analysis of depositional ages in sedimentary sections through the use of Bayesian statistics, allowing for the inference of bounded estimates of true depositional ages and uncertainties from detrital geochronology so long as some minimum age constraints are present. We present two approaches for constructing a Bayesian model of deposit ages, first solving directly for the ages of deposits with the prior constraint that the ages of units must obey stratigraphic ordering, and second describing the evolution of ages with a curve that represents the sediment accumulation rate. Using synthetic examples we highlight how this method preforms in less-than-ideal circumstances. In an example from the Magallanes Basin of Patagonia, we demonstrate how introducing other age information from the stratigraphic section (e.g., fossil assemblages or radiometric dates) and formalizing the stratigraphic context of samples provides additional constraints on and information regarding depositional ages or derived quantities (e.g., sediment accumulation rates) compared to isolated analysis of individual samples.

Screen-printed soft capacitive sensors for spatial mapping of both positive and negative pressures

Released April 05, 2019 13:39 EST

2019, Advanced Functional Materials

Hongyang Shi, Mohammed Al-Rubaiai, Christopher Holbrook, Jinshui Miao, Thassyo Pinto, Chuan Wang, Xiaobo Tan

Soft pressure sensors are one class of the essential devices for robotics and wearable device applications. Despite the tremendous progress, sensors that can reliably detect both positive and negative pressures have not yet been demonstrated. In this paper, we report a soft capacitive pressure sensor made using a convenient and low-cost screen-printing process that can reliably detect both positive and negative pressures from −60 kPa to 20 kPa. The sensor is made with an Ecoflex-0030 dielectric layer, conductive and stretchable poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) (with ionic additives) electrodes and polydimethylsiloxane (PDMS) encapsulation layers. Air gaps are designed and incorporated into the dielectric layer to significantly enhance the sample deformation and pressure response especially to negative pressure. The sensor exhibits repeatable response for thousands of cycles, even under bending or stretching conditions. Lastly, to demonstrate the practical application, a 12×12-pixel sensor array that can automatically measure both positive and negative pressure distributions has been reported under −20 kPa and 10 kPa.

Invasive species research—Science for detection, containment, and control

Released April 05, 2019 11:50 EST

2019, Fact Sheet 2018-3080

Earl W. Campbell, Cynthia S. Tam, Suzanna C. Soileau

Invasive species research within the U.S. Geological Survey’s Ecosystems Mission Area focuses on invasive organisms throughout the United States. U.S. Geological Survey scientists work with partners in the Department of the Interior, other Federal, State and Territorial agencies, Tribes, industry, and agriculture to provide the information needed to help solve problems posed by these invaders. Key components of U.S. Geological Survey invasive species science include the development of novel prevention, prediction, early detection, containment, and control tools.

Living with volcano hazards

Released April 05, 2019 10:42 EST

2019, Fact Sheet 2018-3075

Wendy K. Stovall, Carolyn L. Driedger, Elizabeth G. Westby, Lisa M. Faust

Volcanic eruptions are among Earth’s most dramatic and powerful agents of change. Ash, mudflows, and lava flows can devastate communities near volcanoes and cause havoc in areas far downwind, downstream, and downslope. Even when a volcano is quiet, steep volcanic slopes can collapse to become landslides, and large rocks can be hurled by powerful steam blasts. Hazardous volcanic conditions might last for a day or decades, all the while threatening people’s health and safety. Scientists with the U.S. Geological Survey and partner agencies assess hazards and closely monitor activity at the Nation’s volcanoes. They provide volcano updates and warnings of hazardous situations, as well as guidance on actions to take. You can prepare your family and community by familiarizing yourself with the types of hazards at volcanoes near where you live and visit.

Coral skeleton δ15N as a tracer of historic nutrient loading to a coral reef in Maui, Hawaii

Released April 05, 2019 09:10 EST

2019, Scientific Reports (9) 1-10

Joseph Murray, Nancy G. Prouty, Sara E. Peek, Adina Paytan

Excess nutrient loading to nearshore environments has been linked to declining water quality and ecosystem health. Macro-algal blooms, eutrophication, and reduction in coral cover have been observed in West Maui, Hawaii, and linked to nutrient inputs from coastal submarine groundwater seeps. Here, we present a forty-year record of nitrogen isotopes (δ15N) of intra-crystalline coral skeletal organic matter in three coral cores collected at this site and evaluate the record in terms of changes in nitrogen sources. Our results show a dramatic increase in coral δ15N values after 1995, corresponding with the implementation of biological nutrient removal at the nearby Lahaina Wastewater Reclamation Facility (LWRF). High δ15N values are known to be strongly indicative of denitrification and sewage effluent, corroborating a previously suggested link between local wastewater injection and degradation of the reef environment. This record demonstrates the power of coral skeletal δ15N as a tool for evaluating nutrient dynamics within coral reef environments.

Hydrologic function of rapidly induced biocrusts

Released April 05, 2019 09:07 EST

2019, Ecohydrology

Stephen E. Fick, Nichole N. Barger, Michael C. Duniway

In dryland ecosystems, land degradation and erosion pose severe threats to ecosystem productivity and human wellbeing. Bio‐inoculation of degraded soils with native biological soil crusts ('biocrusts') is a promising yet relatively untested means to improve soil stability and hydrologic function (i.e. increase infiltration and reduce runoff). In a degraded semi‐arid grassland on the Colorado Plateau, we studied the establishment and hydrologic function (via simulated rainfall) of induced biocrusts grown with and without an organic soil stabilizer (psyllium, derived from Plantago sp.), after a period of four months. We found evidence of biocrust establishment, including significantly higher biocrust cover, chlorophyll a, and exopolysaccarides (EPS) in inoculated plots compared to controls. Plots inoculated with biocrust had higher runoff and sediment yields than controls during rainfall simulation. However, this effect was mitigated in plots where stabilizer was added, resulting in greater soil aggregate stability and higher levels of infiltration (reduced total runoff). The time to ponding was significantly greater than control for all inoculated plots, suggesting that induced biocrusts may be most effective at improving infiltration under low‐intensity, smaller precipitation events. Notably, the biocrusts in this study lacked the rough surface microtopography which is common in well‐developed biocrusts regionally and likely instrumental in slowing overland flow and increasing infiltration for larger rain events. These results highlight the temporal lag that may exist between apparent and functional restoration of biocrusts. In addition, the simultaneous additions of stabilizing amendments with biocrust inoculum may work collectively to achieve both short and long‐term restoration targets.

Residence time controls on the fate of nitrogen in flow‐through lakebed sediments

Released April 05, 2019 09:05 EST

2019, Journal of Geophysical Research: Biogeosciences

Tyler B. Hampton, Jay P. Zarentske, Martin A. Briggs, Kamini Singha, Judson W. Harvey, Frederick D. Day-Lewis, Farzaneh MahmoodPoor Dehkordy, John W. Lane Jr.

For many glacial lakes with highly permeable sediments, water exchange rates control hydrologic residence times within the sediment‐water interface (SWI) and the removal of reactive compounds such as nitrate, a common pollutant in lakes and groundwater. Here we conducted a series of focused tracer injection experiments in the upper 20 cm of the naturally downwelling SWI in a flow‐through lake on Cape Cod, MA. We systematically varied residence time and reactant controls on nitrate processing, using isotopically labeled 15N nitrate to monitor the effect of these changes on nitrate removal via denitrification. The addition of acetate, a labile carbon compound, triggered the lake SWI to switch from net production to net removal of nitrate. When acetate was combined with increased residence time created by controlled reductions in water flux, we observed a fivefold increase in nitrate removal, a 26‐fold increase in N2 production, and a 42‐fold increase in N2O production. We demonstrate that water residence time is an important control on the fate of nitrate in these lake SWIs and illustrate that seasonal conditions that alter lake exchange rates and variability in lake carbon may predict dynamic nitrate removal across the SWI. Additionally, observed N2O production during the oxic pore water experiments paired with geophysical characterization of the sediment porosity revealed that the lake SWI has less mobile pores occupying upward of 50% of the total porosity volume, which function as reactive microzones for nitrate processing.

Wetland-scale mapping of preferential fresh groundwater discharge to the Colorado River

Released April 05, 2019 09:02 EST

2019, Groundwater

Martin A. Briggs, Nora Nelson, Philip M. Gardner, D. Kip Solomon, Neil Terry, John W. Lane Jr.

Quantitative evaluation of groundwater/surface water exchange dynamics is universally challenging in large river systems, because existing methodology often does not yield spatially‐distributed data and is difficult to apply in deeper water. Here we apply a combined near‐surface geophysical and direct groundwater chemical toolkit to refine fresh groundwater discharge estimates to the Colorado River through a 4‐km2 wetland that borders the town of Moab, Utah, USA. Preliminary characterization of raw electromagnetic imaging (EMI) data, collected by kayak and by walking, was used to guide additional direct‐contact electrical measurements and installation of new monitoring wells. Chemical data from the wells strongly supported the EMI spatial characterization of preferential fresh groundwater discharge embedded in natural brine groundwaters and weighted to the southern wetland section. Inversion of the EMI data revealed sub‐meter scale detail regarding bulk electrical conductivity zonation across approximately 15.5 km of transects, collected in only 3 days. This electrical detail indicates processes such as salinization of the unsaturated zone and direct discharge through the Colorado River sediments and a tributary creek bed. Overall, the study contributed to a substantial reduction in fresh groundwater discharge estimates previously made using sparse existing well data and a simplified assumption of diffuse fresh groundwater discharge below the entire wetland. EMI will likely become a widely used tool in systems with natural electrical contrast as groundwater/surface water hydrogeologists continue to recognize the prevalence of preferential groundwater discharge processes.

Multi-scale preferential flow processes in an urban streambed under variable hydraulic conditions

Released April 05, 2019 08:59 EST

2019, Journal of Hydrology (573) 168-179

Farzaneh MahmoodPoor Dehkordy, Martin A. Briggs, Frederick D. Day-Lewis, Kamini Singha, Ashton Krajnovich, Tyler B. Hampton, Jay P. Zarnetske, Courtney R. Scruggs, Amvrossios C. Bagtzoglou

Spatially preferential flow processes occur at nested scales at the sediment-water interface (SWI), due in part to sediment heterogeneities, which may be enhanced in flashy urban streams with heavy road sand influence. However, several factors, including the flow-rate dependence of preferential hyporheic flow and discrete groundwater discharge zones are commonly overlooked in reach-scale models of groundwater/surface water exchange. Using a series of controlled-head tracer-injection experiments coupled with cm-scale geophysics within the highly reactive upper 30 cm of the hyporheic zone of an urban stream, we quantified the flow dependence of local less-mobile porosity volume, mass-transfer rate coefficient, and the resulting local residence time in the less-mobile pore space at three controlled downward fluid fluxes (0.8, 2, and 3 m/d). Experiments were performed in two adjacent streambed locations, representing different sediment bulk vertical permeability. Less-mobile porosity parameters were generally substantial and similar between the two streambed locations; though a more competent, thin, organic layer at ∼15 cm depth in one location strongly impacted tracer loading, flushing dynamics, and local residence times. Increased downward flux led to (1) a decrease in less-mobile porosity residence time in all experiments, and (2) an increase in less-mobile porosity fraction for most experiments. Additionally, at the larger stream reach-scale, surface electrodes for electrical resistivity measurement were installed along 22 m of the wetted stream channel. These surface electrode measurements were collected during a natural storm flow event, which revealed widespread, short-term, flushing (e.g. <3 h) of the hyporheic zone with stream water, followed by longer-term (e.g. >60 h) flushing of the SWI with riparian zone groundwater. Flow dependence of preferential hyporheic zone flowpaths, like in the controlled tracer experiments, was also observed in these reach-scale electrical resistivity tomography measurements. Our findings reveal that the spatial and temporal dependence of preferential flow processes create highly dynamic SWI conditions that will affect the physical and coupled biogeochemical functions of the SWI in urbanized, sand-impacted streams.

Bathymetric contour map, surface area and capacity table, and bathymetric change map for Sugar Creek Lake near Moberly, Missouri, 2018

Released April 04, 2019 11:06 EST

2019, Scientific Investigations Map 3431

Joseph M. Richards, Richard J. Huizinga, Jarrett T. Ellis

Managers of water-supply lakes need an accurate estimate of the lake capacity to ensure that enough water is available for uses such as: providing consistent recreation pool levels, preserving downstream aquatic habitat, flood abatement, water supply, and power generation. Lake capacity is particularly important for managers of water-supply lakes during periods of drought, unexpected population growth, or exceptionally high water use in the area supplied by the lake. Sedimentation, primarily from runoff into the lake, will cause a loss of storage capacity as a lake ages; as a result, the capacity table for the lake (if one exists) will overestimate the actual capacity. Lake bathymetric changes can be demonstrated through periodic surveying, and rates of sediment accumulation can be calculated so that managers can better regulate the water supply.

The U. S. Geological Survey, in cooperation with the Missouri Department of Natural Resources, completed a bathymetric survey of Sugar Creek Lake in December 2003.  Sugar Creek Lake, constructed in 1922, is about 4 miles northwest of Moberly, Missouri, in Randolph County and has a surface area of about 330 acres at the spillway elevation of 746.8 feet. The lake primarily is used for recreation and drinking-water supply for the town of Moberly,  Missouri.

In September 2018, the  U. S. Geological Survey, in cooperation with the Missouri Department of Natural Resources and the City of Moberly,  Missouri, surveyed the bathymetry of Sugar Creek Lake to prepare an updated bathymetric map and a surface area and capacity table. The 2003 survey was compared with the 2018 survey to document the changes in the bathymetric surface. The comparison found that in the 14.7 years between the two surveys the lake had lost 230 acre-feet of capacity and had an average sediment accumulation of 0.96 feet.

Estimating quick-flow runoff at the monthly timescale for the conterminous United States

Released April 04, 2019 09:43 EST

2019, Journal of Hydrology (573) 841-854

Meredith Reitz, Ward E. Sanford

The quantitative estimation of the quick-flow runoff component of streamflow is required for many hydrologic applications. Estimation at the monthly timescale and national spatial scale would be particularly useful for national water availability modeling. This paper reviews a sample of commonly used equations for quick-flow runoff, including several currently in use in continental-scale models. The review shows the wide range of equation forms or heuristics currently in use to predict quick-flow runoff, the limited spatial scale over which these equations are often developed or calibrated, and the scarcity of well-tested equations available for quick-flow runoff at the monthly timescale. Data were gathered from a set of 1301 gaged watersheds across the United States to test a range of equations from the literature, along with several alternative equations, to assess and compare their performance in predicting quick-flow runoff at the monthly timescale. The highest-performing equation was selected for application to monthly maps of explanatory variables to produce monthly quick-flow runoff water budget contribution maps. This equation is a regression against precipitation, soil saturated hydraulic conductivity, surficial geology type, and slope data. Its application indicates that average quick-flow runoff across the conterminous United States in the winter exceeds that in the summer by up to a factor of three. The monthly maps were explored and evaluated for the timespan of 2000-2015. The comparison of equation forms and produced monthly maps will be useful for a variety of hydrologic modeling and monitoring applications.

The influence of shelf bathymetry and beach topography on extreme total water levels: Linking large-scale changes of the wave climate to local coastal hazards

Released April 04, 2019 09:08 EST

2019, Coastal Engineering

Katherine A. Serfain, Peter Ruggiero, Patrick L. Barnard, Hilary F. Stockdon

Total water levels (TWLs) at the coast are driven by a combination of deterministic (e.g., tides) and stochastic (e.g., waves, storm surge, and sea level anomalies) processes. The contribution of each process to TWLs varies depending on regional differences in climate and framework geology, as well as local-scale variations in beach morphology, coastal orientation, and shelf bathymetry. Large-scale changes to the climate altering the frequency, direction, and intensity of storms, may therefore propagate to the nearshore differently, amplifying or suppressing local coastal hazards and changing the exposure of coastal communities to extreme TWLs. This study investigates the hydrodynamic and geomorphologic factors controlling local TWLs along high-energy United States coastlines where wave-influences dominate TWLs. Three study sites in the states of Washington, Oregon, and California are chosen to explore how regional and local differences in beach topography and wave transformation over shelf bathymetry drives variations in the magnitude and impacts of extreme TWLs. Results indicate that TWLs are most influenced by wave transformation processes in locations with steep beach slopes (which drive larger relative contributions of wave runup) and complex offshore bathymetry, while beach topography influences the severity of coastal impacts. Once the relative morphologic controls on TWLs are better understood, hypothetical future climate scenarios are explored to assess how changes to the average deepwater wave climate (height, period, and direction) may alter local TWLs when compared to estimates of likely sea level rise and future coastal management strategies. Changes to the wave climate are found to be as detrimental to the coastline as sea level rise in some locations, where small variations of the TWL drive large, nonlinear changes in hours of impact to the backshore beach. Overall, this study develops an approach for quantifying the range of hydrodynamic and morphologic controls on the magnitude of TWLs which will ultimately better prepare coastal communities for uncertain changes to the global climate.

Annual wastewater nutrient data preparation and load estimation using the Point Source Load Estimation Tool (PSLoadEsT)

Released April 04, 2019 07:00 EST

2019, Open-File Report 2019-1025

Lillian E. Gorman Sanisaca, Kenneth D. Skinner, Molly A. Maupin

The Point-Source Load Estimation Tool (PSLoadEsT) provides a user-friendly interface for generating reproducible load calculations for point source dischargers while managing common data challenges including duplicates, incompatible input tables, and incomplete or missing nutrient concentration or effluent flow data. Maintaining a consistent method across an entire study area is important when estimating loads to be used as calibration data for regional water-quality models. PSLoadEsT is written using the open-source programming language R and has an easy-to-use interface written in Visual Basic for Applications® within a Microsoft Access® database file that guides the user through the necessary steps to estimate point source loads. The purpose of this report is to provide a detailed user guide for PSLoadEsT.

Point-source nutrient loads to streams of the conterminous United States, 2012

Released April 04, 2019 07:00 EST

2019, Data Series 1101

Kenneth D. Skinner, Molly A. Maupin

Total nitrogen and phosphorous loads were estimated for 5,430 major point-source facilities (all types) and 11,537 minor wastewater treatment facilities discharging to streams in the conterminous United States during 2012. Facilities classified as a major discharger are typically a facility that discharges greater than one million gallons of water per day however some industrial facilities are classified as a major based on specific criteria developed by the U.S. Environmental Protection Agency (EPA) and the National Pollutant Discharge Elimination System state program. Data documenting discharge information from point sources were obtained from the EPA’s Integrated Compliance Information System (ICIS) and Permit Compliance System (PCS). When available, actual nutrient concentration measurements were used to calculate point-source loads. In the many cases in which concentration data were not available in either the ICIS or PCS databases, typical pollutant concentrations (TPCs) were developed using data from similar facilities. A new method for calculating TPCs was implemented that allows varying amounts of nutrient concentration data and (or) varying numbers of facilities to determine TPCs. This new method minimized the effect that any single facility discharging extremely large nutrient concentrations had on resultant TPC values. Because of the smaller TPC values from this new TPC method, the total nutrient load for many states was reduced compared to previous TPC methods.

Major wastewater treatment facilities are the largest contributor of nutrient loads to streams even though there are almost three times as many minor wastewater treatment facilities. Specifically, 4,218 major wastewater treatment facilities account for 94 percent of the total nitrogen load for the conterminous United States, whereas 11,397 minor wastewater treatment facilities contribute 6 percent of the total nitrogen load. Total phosphorous loads are similarly divided among major (93 percent) and minor (7 percent) wastewater treatment facilities. Total nitrogen loads, including all facility types, primarily are from wastewater treatment facilities and some petroleum refining facilities. Total phosphorous loads also are primarily from wastewater treatment facilities, but several manufacturing facilities such as corn milling, pulp and paper mills, and industrial chemical facilities also contribute to total phosphorous loads.

Which trees die during drought? The key role of insect host-tree selection

Released April 03, 2019 12:31 EST

2019, Journal of Ecology

Nathan L. Stephenson, Adrian J. Das, Nicholas J. Ampersee, Beverly M Bulaon, Julie L. Yee

1. During drought, the tree subpopulations (such as size or vigor classes) that suffer disproportionate mortality can be conceptually arrayed along a continuum defined by the actions of biotic agents, particularly insects. At one extreme, stress dominates: insects are absent or simply kill the most physiologically stressed trees. At the opposite extreme, host selection dominates: outbreaking insects kill trees independently of their stress, instead selecting trees based on size or other traits. Intermediate responses are also possible. Yet for mixed-species forests, we lack a broad understanding of the relative importance of insects in determining exactly which subpopulations of trees suffer disproportionate mortality during drought, and whether these subpopulations differ among co-occurring tree species. 2. During an extreme drought, we documented the roles of native bark beetles in the mortality of five tree species in California’s Sierra Nevada. We analyzed patterns and agents of tree mortality in 12 permanent plots, and patterns of mortality in 89 temporary plots. 3. Most tree mortality was associated with bark beetles. But the growth rates (an indicator of chronic stress) and sizes of trees that suffered greatest bark-beetle-related mortality differed sharply among tree taxa, variously conforming with domination by stress (Abies concolor), domination by host selection (Pinus lambertiana and P. ponderosa), or a mix of the two (Calocedrus decurrens). Quercus kelloggii mortality remained relatively low. Thus, even during extreme drought substantial proportions of stressed trees survived because they were of sizes that mostly avoided fatal insect attack. Conversely, substantial proportions of comparatively unstressed trees died because they were of sizes that were selectively killed by outbreaking insects. 4. Synthesis. Native bark beetles were primarily responsible for determining which subpopulations of trees suffered greatest mortality during drought. However, idiosyncratic host-tree selection by the different bark beetle taxa meant that the tree subpopulations suffering greatest mortality differed strikingly among tree taxa – for example, high mortality of small trees of one species, but of large trees of another. If idiosyncratic host-tree selection by biotic mortality agents proves to be a generally common phenomenon, it could help explain weak broad-scale correlations between tree traits and tree mortality during drought.

Environmental and geomorphological changes on the eastern North American Continental Shelf across the Paleocene-Eocene Boundary

Released April 03, 2019 08:24 EST

2019, Paleoceanography and Paleoclimatology

Marci M. Robinson, Whittney Spivey

Foraminiferal evidence from two sites in southern Maryland, eastern United States, reveals a series of rapid ecological changes on the continental shelf during the onset of the Paleocene-Eocene Thermal Maximum (PETM). Benthic and planktic foraminifer assemblages from the South Dover Bridge (SDB) and Mattawoman Creek-Billingsley Road (MCBR) cores in the central Salisbury Embayment record changing latest Paleocene and earliest Eocene ecological conditions that began prior to the carbon isotope excursion (CIE) that marks the beginning of the PETM. The foraminiferal response reflects increases in productivity first in bottom water and then in the mixed layer, a minor dissolution event, and rising sea-surface temperatures in the latest Paleocene. Relative sea level changes, a sudden change in sedimentary regime, a decrease in bottom water oxygenation, and a downward expansion of the mixed layer occurred across the PETM onset. In the earliest Eocene, foraminiferal assemblages document a gradual shallowing of the thermocline and/or cooling of the surface layer. While SDB assemblages support a rise in sea level across the PETM onset, MCBR assemblages record a drop in sea level interpreted as delta progradation. Transitional carbon isotope values characterizing the nature of the CIE are recorded in these delta sediments. We present an initial bathymetric reconstruction of the Salisbury Embayment showing the physical effects of the CIE onset on shelf morphology and highlight the importance of understanding coastal zone processes when examining shelf sediments.

Terrestrial lidar data of the February 14, 2019 Sausalito Boulevard Landslide, Sausalito, California

Released April 02, 2019 08:23 EST

2019, Data Series 1112

Brian D. Collins, Skye C. Corbett

On February 14, 2019, just before 2:56 am local time (Pacific Standard Time), a landslide initiated from the hillslopes above the Hurricane Gulch section of the City of Sausalito, Marin County, California. The landslide, specifically classified as a debris flow, overran a road (Sausalito Boulevard) immediately below the landslide source area and impacted a residential structure that subsequently toppled downslope and collided with another residential structure. The second structure then crossed a lower road (Crescent Avenue) that runs along the base of the slope before the mixture of soil and structural debris came to rest in and near the valley axis that drains the lower area of Hurricane Gulch.

The U.S. Geological Survey responded to this event within hours of the landslide and provided situational awareness of possible secondary landslide hazards associated with the unstable slope. The USGS also rapidly mobilized its topographic surveying capabilities (specifically, GPS and terrestrial lidar devices) and collected a three-dimensional point cloud model of the landslide source area and surrounding terrain to capture the as-failed condition of the slope for use in potential future studies. This report summarizes the methods and available data collected during this response.

Potential sea level rise for the Chitimacha Tribe of Louisiana

Released April 01, 2019 17:00 EST

2019, Open-File Report 2019-1030

Kathryn A. Spear, William Jones, Kereen Griffith, Blair E. Tirpak, Kimberly Walden

Situated in the Mississippi Alluvial Plain of the Gulf Coast Prairie Landscape Conservation Cooperative (GCP LCC), the Chitimacha Tribe is one of four federally recognized tribes in Louisiana. The Tribal seat, trust lands/ reservation, and adjacent Tribal owned lands are located near Charenton, Louisiana, totaling nearly 1,000 acres. The Chitimacha, with a population of approximately 1,400 people, are currently impacted by storm surge, which is expected to increase with climate change. The additional stress from storms will likewise increase the vulnerability to catastrophic impact in the event of a breach in the Atchafalaya Basin Spillway levee. A collaborative effort between the U.S. Geological Survey (USGS) and the Chitimacha Tribe has been initiated to provide resources and expertise to increase the Tribe’s ability to prevent, plan, and prepare for these environmental challenges. By enhancing technical skills, providing access to environmental data, and increasing awareness of environmental issues, the Chitimacha will be better prepared to plan and adapt to the environmental impacts facing their lands related to land use and climate change.

For this project, USGS researchers asked how Chitimacha Tribal Lands might be impacted by future sea level rise scenario projections. These models illustrate some flooding within the northernmost boundary of Chitimacha Tribal Lands.

Bioavailable iron production in airborne mineral dust: Controls by chemical composition and solar flux

Released April 01, 2019 15:44 EST

2019, Atmospheric Environment (205) 90-102

Eshani Hettiarachchi, Richard L. Reynolds, Harland L. Goldstein, Bruce M. Moskowitz, Gayan Rubasinghege

A large part of oceanic biological production is limited by the scarcity of dissolved iron. Mineral dust aerosol, processed under acidic atmospheric conditions, is the primary natural source of bioavailable iron to oceanic life. However, synergistic and antagonistic effects of non-Fe-containing minerals on atmospheric processing of Fe-containing minerals and Fe solubilization are poorly understood. The current study focuses on mineralogical influences of non-Fe-bearing semiconductor minerals, such as titanium dioxide (TiO2), on the dissolution of iron in selected natural mineral dust aerosols under atmospherically relevant conditions. Further, the role of elevated Ti concentrations in dust is evaluated using magnetite, a proxy for Fe(II) containing minerals, under both dark and light conditions. Our results highlight that relatively higher Ti:Fe ratios, regardless of their total Fe content, enhances the total iron dissolution in mineral dust aerosols as well as in magnetite. Moreover, elevated Ti percentages also yield high Fe(II) fractions in mineral dust systems under dark conditions. Upon irradiation however, dissolved Fe(II) is suppressed by high Ti levels due to the involvement of photochemical redox cycling reactions with hydroxyl radicals (OH). These synergistic and antagonistic effects of Ti are further evaluated by altering the chemical composition of natural dusts with artificially added anatase (TiO2) and synthetic amorphous titania. The current study reveals important mineralogical controls by non-Fe-bearing minerals on dust iron dissolution to better understand global iron mobilization.

Functional variation at an expressed MHC class IIß locus associates with Ranavirus infection intensity in larval anuran populations

Released April 01, 2019 15:32 EST

2019, Immunogenetics (17) 335-346

Anna E. Savage, Carly R. Muletz-Wolz, Evan H. Campbell Grant, Robert C. Fleischer, Kevin P. Mulder

Infectious diseases are causing catastrophic losses to biodiversity globally. Iridoviruses in the genus Ranavirus are among the leading causes of amphibian disease-related mortality. Polymorphisms in major histocompatibility complex (MHC) genes are significantly associated with variation in amphibian susceptibility to pathogens. MHC genes encode diverse cell-surface molecules that can recognize and bind to a wide array of pathogen peptides, and are divided into two classes. While MHC class I genes are the classic mediators of viral acquired immunity, larval amphibians do not express them. However, MHC class II gene diversity may be an important predictor of Ranavirus susceptibility in larval amphibians, the life stage most susceptible to Ranavirus. We surveyed natural populations of larval wood frogs (Lithobates sylvaticus), which are highly susceptible to Ranavirus, across 17 ponds and two years in Maryland, USA. We sequenced the peptide-binding region of an expressed MHC class IIß locus and assessed allelic and genetic diversity. We converted alleles to functional supertypes and determined if physiochemical properties of peptide-binding regions influenced host responses to Ranavirus. Among 334 sampled individuals, 26% were infected with Ranavirus, and among infected individuals the average intensity was 7.12 x 107 virus copies. We recovered 20 unique MHC class IIß alleles that fell into two deeply diverged clades and seven functional supertypes. Variation in MHC supertypes were associated with Ranavirus infection intensity, but not prevalence. MHC supertype heterozygotes and individuals with the MHC supertype genotype ST1/ST7 had significantly lower Ranavirus infection intensity compared to homozygotes and all other genotypes. We conclude that MHC class IIß functional genetic variation is an important component of Ranavirus susceptibility. Identifying immune system gene signatures linked to variation in disease susceptibility can inform mitigation strategies for combatting global amphibian declines.

Living with wildfire in Montezuma County, Colorado: 2015 data report

Released April 01, 2019 14:38 EST

2019, Research Note RMRS-RN-81

Hannah Brenkert-Smith, James R. Meldrum, Pamela Wilson, Patricia A. Champ, Christopher M. Barth, Angela Boag

Residents in the wildland-urban interface (WUI) can play an important role in reducing wildfire’s negative effects by performing wildfire risk mitigation on their property. This report offers insight into the wildfire risk mitigation activities and related considerations, such as attitudes, experiences, and concern about wildfire, for people with homes in select communities in Montezuma County, Colorado. Data come from a social survey and parcel-level rapid wildfire risk assessments administered by FireWise of Southwest Colorado. Results are presented both in graphical form and as detailed summary statistics (in appendices). As we recognize that results from similar surveys and assessments in other communities may differ, these linked datasets contribute to a broader effort to understand decisions about wildfire risk mitigation on private property. Results can facilitate long-term monitoring, management, and educational practices concerning the mitigation of wildfire risk in WUI communities.

Relative prediction intervals reveal larger uncertainty in 3D approaches to predictive digital soil mapping of soil properties with legacy data

Released April 01, 2019 13:45 EST

2019, Geoderma (347) 170-184

Travis Nauman, Michael C. Duniway

Fine scale maps of soil properties enable efficient land management and inform earth system models. Recent efforts to create soil property maps from field observations tend to use similar tree-based machine learning interpolation approaches, but often deal with depth of predictions, validation, and uncertainty differently. One of the main differences in approaches is whether to model individual depths of interest separately as ‘2D’ models, or to create models that incorporate depth as a predictor variable creating a ‘3D’ model that can make pre-dictions for all depths. It is unclear how choice of 2D or 3D approach influences model accuracy and uncertainty due to lack of direct comparison and inconsistent presentation of results in past studies. This study compares 2D and 3D methods for mapping soil electrical conductivity (salinity), pH, sum of fine and very fine sands, and organic carbon at 30 m resolution for the upper 432,000 km 2 of the Colorado River Watershed of the United States of America. A new, simple, model-agnostic relative prediction interval (RPI) approach to report un-certainty is presented that scales prediction interval width to the 95% interquantile width of the original training sample distribution. The RPI approach enables direct comparison of uncertainty between properties and depths and is easily interpretable by end users. Results indicate that 3D mapping of soil properties with strong variation with depth can result in substantial areas with much higher uncertainty that coincide with unrealistic predictions relative to 2D models, even though 3D models had slightly better global cross-validation scores. Maps and global model summaries of RPI proved helpful in identifying these issues with 3D models. These results suggest that the use of RPI or similar approaches to evaluate models can identify accuracy problems not evident in global va-lidation diagnostics.

Using the value of information to improve conservation decision making

Released April 01, 2019 13:41 EST

2019, Biological Reviews (94) 629-647

Friederike C. Bolam, Matthew J. Grainger, Kerrie L. Mengerson, Gavin B. Stewart, William J. Sutherland, Michael C. Runge, Philip J. K. McGowan

Conservation decisions are challenging, not only because they often involve difficult conflicts among outcomes that people value, but because our understanding of the natural world and our effects on it is fraught with uncertainty. Value of Information (VoI) methods provide an approach for understanding and managing uncertainty from the standpoint of the decision maker. These methods are commonly used in other fields (e.g., economics, public health) and are increasingly used in biodiversity conservation. This decision analytical approach can identify the best management alternative to select where the effectiveness of interventions is uncertain, and can help to decide when to act and when to delay action until after further research. We review the use of VoI in the environmental domain, reflect on the need for greater uptake of VoI, particularly for strategic conservation planning, and suggest promising areas for new research. We also suggest common reporting standards as a means of increasing the leverage of this powerful tool. The environmental science, ecology and biodiversity categories of the Web of Knowledge were searched using the terms ‘Value of Information,’ ‘Expected Value of Perfect Information,’ and the abbreviation ‘EVPI.’ Google Scholar was searched with the same terms, and additionally the terms decision and biology, biodiversity conservation, fish, or ecology. We identified 1225 papers from these searches. Included studies were limited to those that show an application of VoI in biodiversity conservation rather than simply describing the method. All examples of use of VOI were summarised regarding the application of VoI, the management objectives, the uncertainties, models used, how the objectives were measured, and the type of VoI. While the use of VoI appears to be on the increase in biodiversity conservation, the reporting of results is highly variable, which can make it difficult to understand the decision context and which uncertainties were considered. Moreover, it was unclear if, and how, the papers informed management and policy interventions, which is why we suggest a range of reporting standards that would aid the use of VoI. The use of VoI in conservation settings is at an early stage. There are opportunities for broader applications, not only for species-focussed management problems, but also for setting local or global research priorities for biodiversity conservation, making funding decisions, or designing or improving protected area networks and management. The long-term benefits of applying VoI methods to biodiversity conservation include a more structured and decision-focused allocation of resources to research.

The contribution of road-based citizen science to the conservation of pond-breeding amphibians

Released April 01, 2019 12:15 EST

2019, Journal of Applied Ecology (56) 988-995

Sean Sterrett, Rachel A. Katz, William R. Fields, Evan H. Campbell Grant

  1. Roadside amphibian citizen science (CS) programmes bring together volunteers focused on collecting scientific data while working to mitigate population declines by reducing road mortality of pond‐breeding amphibians. Despite the international popularity of these movement‐based, roadside conservation efforts (i.e. “big nights,” “bucket brigades” and “toad patrols”), direct benefits to conservation have rarely been quantified or evaluated.

  2. As a case study, we used a population simulation approach to evaluate how volunteer intensity, frequency and distribution influence three conservation outcomes (minimum population size, population growth rate and years to extinction) of the spotted salamander (Ambystoma maculatum), often a focal pond‐breeding amphibian of CS and conservation programmes in the United States.

  3. Sensitivity analysis supported the expectation that spotted salamander populations were primarily recruitment‐driven. Thus, conservation outcomes were highest when volunteers focused on metamorph outmigration as opposed to adult in‐migration—contrary to the typical timing of such volunteer events.

  4. Almost every volunteer strategy resulted in increased conservation outcomes compared to a no‐volunteer strategy. Specifically, volunteer frequency during metamorph migration increased outcomes more than the same increases in volunteer effort during adult migration. Small population sizes resulted in a negligible effect of volunteer intensity. Volunteers during the first adult in‐migration had a relatively small effect compared to most other strategies.

  5. Synthesis and applications. Although citizen science (CS)‐focused conservation actions could directly benefit declining populations, additional conservation measures are needed to halt or reverse local amphibian declines. This study demonstrates a need to evaluate the effectiveness of focusing CS mitigation efforts on the metamorph stage, as opposed to the adult stage. This may be challenging, compared to other management actions such as road‐crossing infrastructure. Current amphibian CS programmes will be challenged to balance implementing evidence‐based conservation measures on the most limiting life stage, while retaining social and community benefits for volunteers.

Mortality due to Tyzzer's disease of muskrats in northern Ohio, USA

Released April 01, 2019 12:06 EST

2019, Journal of Wildlife Diseases

Daniel A. Grear, Julia S. Lankton, Sara Zaleski, Mark Witt, Jeffrey M. Lorch

In 2017, we investigated a mortality event of muskrat (Ondatra zibethicus) in Northwest Ohio, USA, and determined the causes of death to be from Tyzzer's disease due to Clostridium piliforme and Klebsiella pneumoniae septicemia. The gross presentation resembled tularemia, which highlighted the importance of a complete diagnostic investigation.

Life-history model for sockeye salmon (Oncorhynchus nerka) at Lake Ozette, northwestern Washington—Users' guide

Released April 01, 2019 12:03 EST

2019, Open-File Report 2019-1031

Andrea Woodward, Mike Haggerty, Patrick Crain

Salmon populations spawning in the Lake Ozette watershed of northwestern Washington were once sufficiently abundant to support traditional Tribal fisheries, and were later harvested by settlers. However, in 1974 and 1975, the sockeye salmon (Oncorhynchus nerka) harvest decreased to 0 from a high of more than 17,500 in 1949, thus stimulating research into the causes of decrease, which resulted in eventual listing of the population as threatened under the Endangered Species Act in 1999. The listing status was upheld in 2005 and 2014 following 5-year reviews. Meanwhile, research results were compiled in a limiting factors analysis (LFA) and a recovery plan was developed. Although there has been some improvement in sockeye abundance since listing, the numbers remain too low to allow harvest and it is not yet clear which of the many potential limiting factors are most consequential.

As part of the LFA process, a population model was developed to determine values of life-history parameters that would enable the population to survive for 100 years. The model was based on the best available data, but data are limited for the Lake Ozette system. Results informed the qualitative assessment of the importance of limiting factors used to develop the recovery plan for Lake Ozette sockeye. The model was built in Microsoft Excel® and is difficult to use. The purpose of the model described herein is to synthesize the results of the LFA in a form that can be manipulated by resource managers and the public to create scenarios, test hypotheses, and observe sensitivities of results to changes in parameters. The goal is to provide a tool that enables research, monitoring and management to be focused on the most impactful elements and processes, including identifying the information gaps that are most critical to fill.

Geologic map of the central-southeast flank of Mauna Loa Volcano, Island of Hawaii, Hawaii

Released April 01, 2019 11:26 EST

2019, Scientific Investigations Map 2932-B

Frank A. Trusdell, John P. Lockwood

Mauna Loa, the largest volcano on Earth, has erupted 33 times since written descriptions became available in 1832. Some eruptions began with only brief seismic unrest, while others followed several months to a year of increased seismicity. Once underway, its eruptions can produce lava flows that may reach the sea in less than 24 hours, severing roads and utilities. For example, lava flows erupted from the Southwest Rift Zone (SWRZ) in 1950 advanced at an average rate of 9.3 km per hour, and all three lobes reached the ocean within approximately 24 hours (Finch and Macdonald, 1953). Near the eruptive vents, the flows must have traveled even faster. In terms of eruption frequency, pre-eruption warning, and rapid flow emplacement, Mauna Loa poses an enormous volcanic-hazard threat to the Island of Hawai‘i. Volcanic hazards on Mauna Loa may be anticipated, and risk substantially mitigated, by documenting the past activity to refine our knowledge of the hazards and by alerting the public and local government officials of our findings and their implications for hazards assessments and risk.

From the geologic record, we may deduce several generalized facts about the geologic history of the Northeast Rift Zone (NERZ). The middle to uppermost segments of the rift zone were more active in the past 4,000 years than the lower portion of the rift zone. This may be due to buttressing of the lower east rift zone by Mauna Kea and Kīlauea volcanoes. The historical flows that erupted on the north side of the rift zone advanced toward Hilo. This flank of the volcano may be more vulnerable to inundation. Lockwood (1990) noted that the vents of historical activity are migrating to the south. The volcano appears to have a self-regulating mechanism that evenly distributes long-term activity across its flanks. The geologic record also supports this notion; the time prior to the historical period (Age Group 1, pre-A.D. 1832 to 1,000 yrs B.P.; orange units) is dominated by activity on the south side of the NERZ.

Although most Mauna Loa eruptions begin in the summit area at the 12,000-ft elevation (Lockwood and Lipman, 1987), the central-southeast flank has not been the source of any activity. All flows originated from the summit or the upper reaches of the Northeast Rift Zone (NERZ) or the Southwest Rift Zone (SWRZ). The NERZ was the source of eight flank eruptions since 1843. The NERZ extends from the 13,680-ft-high summit towards Hilo (population ~60,000; second-largest city in State of Hawaii). The northern portion of the map area is built entirely on flows erupted from the NERZ. The SWRZ extends from the summit towards Kalae (South Point) at sea level. The southern portion of the map area is built entirely on flows erupted from the SWRZ.

The map area extends from the 10,350-ft elevation on Mauna Loa’s east flank toward the Hawaii Volcanoes National Park and the town of Volcano (population approx. 2,000) in the northeast. At the south boundary of the map area is the town of Pāhala (population approx. 900). This map includes areas adjacent to and downslope of the NERZ and regions east of and directly downslope of Moku‘āweoweo, Mauna Loa’s summit caldera.

The map encompasses 506 km2 of the southeast flank (fig. 1) of Mauna Loa from 10,350-ft elevation to sea level. The map of the central-southeast flank of Mauna Loa shows the distribution and relations of volcanic and surficial sedimentary deposits separated into 15 age groups ranging from a period greater than 50,000 yr B.P. to A.D. 1984. It incorporates previously reported work published in generalized small-scale maps (Lockwood and Lipman, 1987; Lockwood, 1995; Wolfe and Morris, 1996).

This map is the second in a series of five maps that will cover Mauna Loa volcano. See SIM 2932-A at https://doi.org/10.3133/sim2932A.

NOTE: Map sheet 1 contains lines and type with overprint. This feature may be turned on or off in the Adobe Acrobat page display preferences.

Effects of climate, regulation, and urbanization on historical flood trends in the United States

Released April 01, 2019 10:57 EST

2019, Journal of Hydrology (573) 697-709

Glenn Hodgkins, Robert Dudley, Stacey Archfield, Benjamin Renard

Many studies have analyzed historical trends in annual peak flows in the United States because of the importance of flooding to bridges and other structures, and the concern that human influence may increase flooding. To help attribute causes of historical peak-flow changes, it is important to separate basins by characteristics that have different influences on peak flows. We analyzed historical trends by basin type: minimally altered basins, regulated basins (substantial reservoir storage but low urbanization), and urbanized basins (with low reservoir storage). Although many peak-flow magnitude changes were found in the last century across the conterminous United States, the trend magnitude and direction vary strongly by basin type and region. In general, there was a low percentage of significant increases and decreases for minimally altered basins while many regulated basins had significant decreases and the limited number of urbanized basins with long-term record showed a high percentage of increases. For urbanized basins, which are concentrated in the Northeast and Midwest, trend magnitude was significantly correlated with the amount of basin urbanization. For all basins regardless of type, parts of the Northeast quadrant of the U.S. had high concentrations of basins with large and significant increases while parts of the Southwest quadrant had high concentrations of basins with large and significant decreases. Basin regulation appears to have heavily influenced the decreasing trends in the Southwest quadrant; there were many large decreases for this basin type despite overall increases in heavy precipitation in this area. Changes over time in the number of 2-per-year and 1-per-5-year peaks over threshold are consistent with changes in the magnitude of annual peak flows.

Identifying occupancy model inadequacies: Can residuals separately assess detection and presence?

Released April 01, 2019 10:52 EST

2019, Ecology

Wilson Wright, Kathryn M. Irvine, Megan D. Higgs

Occupancy models are widely applied to estimate species distributions, but few methods exist for model checking. Thorough model assessments can uncover inadequacies and allow for deeper ecological insight by exploring structure in the observed data not accounted for by a model. We introduce occupancy model residual definitions that utilize the posterior distribution of the partially latent occupancy states. Residual‐based assessments are valuable because they can target specific assumptions and identify ways to improve a model, such as adding spatial correlation or meaningful covariates. Our approach defines separate residuals for occupancy and detection, and we use simulation to examine whether missing structure for modeling detection probabilities can be distinguished from that for occupancy probabilities. In many scenarios, our residual diagnostics were able to successfully separate inadequacies at the different model levels, but we describe other situations when this may not be the case. Applying Moran's I residual diagnostics to assess models for silver‐haired (Lasionycteris noctivagans) and little brown (Myotis lucifugus) bats only provided evidence of residual spatial correlation among detections. Targeting specific model assumptions using carefully chosen residual diagnostics is valuable for any analysis, and we remove previous barriers for occupancy analyses — lack of examples and practical advice.

Diverse late‐stage crystallization and storage conditions in melt domains from the Youngest Toba Tuff revealed by age and compositional heterogeneity in the last increment of accessory phase growth

Released April 01, 2019 10:18 EST

2019, Contributions to Mineralogy and Petrology (174)

Casey R. Tierney, Mary R. Reid, Jorge A. Vazquez, Craig A. Chesner

The chemical record contained within the nal increment of growth on crystals is utilized to reveal the dynamics and time- scales of magma assembly and storage before eruption of the cataclysmic 2800 km3 Youngest Toba Tu (YTT), Indonesia. In situ U–Th disequilibrium dates and trace element concentrations were obtained via secondary ionization mass spectrometry (SIMS) on unsectioned and unpolished faces of individual zircon and allanite crystals. The six high-silica (> 73 wt% SiO2) pumices from which crystals were derived are among the more evolved and lower crystallinity (< 25 wt%) pumices from the YTT eruption, and likely represent the melt-dominated portion of the magma system. Discrete SIMS measurement cycles were coupled with statistical treatments to detect zircon and allanite surface zoning domains at the ~ 1 μm scale. Coupled r-MELTS and accessory phase saturation modeling indicates that at the granite ternary minimum or ‘eutectoid’ conditions that de ne this portion of the YTT, zircon and allanite crystallization is dependent on and proportionate to major phase crystallization, and is more limited than at pre-eutectoid conditions. A lower proportion of near-eruption zircon surface ages in the comparatively cool and wet YTT relative to other hotter and drier voluminous silicic eruptions could re ect the in u- ence of eutectoid storage conditions on magmatic responses to remobilization-related magmatic recharge.

Upper mantle earth structure in Africa from full-wave ambient noise tomography

Released April 01, 2019 09:20 EST

2019, Geochemistry, Geophysics, Geosystems (20) 120-147

Erica L. Emry, Yang Shen, Andrew A. Nyblade, Ashton Flinders, Xueyang Bao

Our understanding of the tectonic development of the African continent and the interplay between its geological provinces is hindered by unevenly distributed seismic instrumentation. In order to better understand the continent, we used long-period ambient noise full waveform tomography on data collected from 186 broadband seismic stations throughout Africa and surrounding regions to better image the upper mantle structure. We extracted empirical Green’s functions from ambient seismic noise using a frequency-time normalization method and retrieved coherent signal at periods of 7-340 seconds. We simulated wave propagation through a heterogeneous Earth using a spherical finite-difference approach to obtain synthetic waveforms, measured the misfit as phase delay between the data and synthetics, calculated numerical sensitivity kernels using the scattering integral approach, and iteratively inverted for structure. The resulting images of isotropic, shear wavespeed for the continent reveal segmented, low-velocity upper mantle beneath the highly magmatic northern and eastern sections of the East African Rift System (EARS). In the southern and western sections, high-velocity upper mantle dominates, and distinct, low-velocity anomalies are restricted to regions of current volcanism. At deeper depths, the southern and western EARS transitions to low-velocities. In addition to the EARS, several low-velocity anomalies are scattered through the shallow upper mantle beneath Angola and North Africa, and some of these low-velocity anomalies may be connected to a deeper feature. Distinct upper mantle high-velocity anomalies are imaged throughout the continent and suggest multiple cratonic roots within the Congo region, and possible cratonic roots within the Sahara Metacraton.

Sources, timing, and fate of sediment and contaminants in the nearshore: insights from geochemistry

Released March 31, 2019 09:16 EST

2019, Conference Paper, 2018 Salish Sea Toxics Monitoring Synthesis: A Selection of Research

Renee K. Takesue, Kathleen E. Conn, Margaret Dutch

Rivers in Cascade watersheds carry sediment with a volcanic composition that is distinct from the plutonic composition of the Puget lowlands. Compositional properties (signatures) allow discrimination of river-sourced Cascade from lowland sediment, and inferences about transport pathways. Surface sediment on land contains atmospheric radionuclides whose known decay rates define monthly (7Be) and decadal (210Pb) timescales of sediment inputs from land to nearshore regions. We used geochemical signatures to source river-borne sediment in two urban embayments in Cascade watersheds: Commencement Bay (CB) and Bellingham Bay (BB). We concurrently determined sediment contaminant levels and, in CB, used geochemical aging to distinguish contaminants in recent winter outflow from those that were pre-existing. Methods are described in Takesue et al. (2017). Geochemical signatures showed that Puyallup River (PU)-sourced fine sediment (<63 µm) accumulated more along the northeast (NE) shore of CB than the southwest: median 91% and 69%, respectively. River-sourced sediment from recent winter storms, containing higher 7Be activities (open circles, Fig. 1A), also accumulated on the NE shore and had lower contents of PAHs, fecal sterols, PCBs, and potentially toxic metals (TM) compared to the south shore; only PBDEs were higher (column graphs, Fig. 1A). Lower 7Be and 210Pb activities in south shore sediment indicated that contaminants there were associated with older sediment. Existing sediment in CB contained higher levels of urban contaminants than new PU material. No PAH, PCB, or TM levels in CB exceeded Washington State marine sediment quality standards (WAMSQS). Geochemical signatures were not distinct in the Nooksack River watershed and lowlands, precluding sediment sourcing in BB. PAH ratios in BB sediments were ubiquitous (open circles, Fig. 1B), suggesting atmospheric rather than riverine transport, and had values indicating biomass/coal combustion sources, except for three sites along the urban waterfront that had values indicative of vehicle emissions (closed circles, Fig. 1B). Elevated TM occurred offshore of Fairhaven (cadmium, Cd; copper, Cu; lead, Pb; zinc, Zn), Whatcom Creek Waterway (Pb, Zn), and the marina (Cu, Zn). No PAH or TM concentrations in BB exceeded WAMSQS. Insights gained from sediment geochemistry about the sources, timing, transport, and fate of riverborne fine sediment and contaminants in nearshore regions are valuable components of monitoring programs that can help guide habitat restoration and resource management decisions toward effective and sustainable outcomes.

Digital database of the geologic map of the middle east rift geothermal subzone, Kīlauea Volcano, Hawai‘i

Released March 29, 2019 12:27 EST

2019, Data Series 1111

Michael H. Zoeller, Frank A. Trusdell, Richard B. Moore

This database release contains all the information used to produce Geologic Investigations Series I-2614 (https://pubs.usgs.gov/imap/2614/). The main component of this digital release is a geodatabase prepared using ArcGIS, but Esri shapefiles are included as well.

Kīlauea is an active shield volcano in the southeastern part of the Island of Hawai‘i. The middle East Rift Zone (MERZ) map includes about 27 square kilometers of the MERZ and shows the distribution of the products of 34 separate eruptions during late Holocene time. Lava flows erupted during 1983–86 have reached the mapped area. The subaerial part of the MERZ is 3–4 km wide and about 18 km long. It is a constructional ridge, 50–150 m above the adjoining terrain, marked by low spatter ramparts and cones as high as 60 m. Lava typically flowed either northeast or southeast, depending on vent location relative to the topographic crest of the rift zone. The MERZ receives more than 100 inches of rainfall annually and is covered by tropical rain forest. Vegetation begins to grow on lava a few months after its eruption. Relative heights of trees can be a guide to relative ages of underlying lava flows, but proximity to faults, presence of easily weathered cinders, and human activity also affect the rate of growth. The rocks have been grouped into five basic age groups. The framework for the ages assigned is provided by eight radiocarbon ages from nearby mapping by the authors and a single date from within this investigation area. The numerical ages are supplemented by observations of stratigraphic relations, degree of weathering, soil development, and vegetative cover.

Geology and biostratigraphy of the Upper Floridan aquifer in the greater Savannah region, Georgia and South Carolina

Released March 29, 2019 10:34 EST

2019, Stratigraphy (16) 41-62

Jean M. Self-Trail, Mercer Parker, John T. Haynes, Arthur P. Schultz, Paul. F. Huddleston

The Upper Floridan aquifer (UFA) of South Carolina, Georgia, Alabama, Mississippi, and Florida has been considered a regionally continuous stratigraphic sequence of Eocene to Miocene carbonate strata, with documented unconformities based on lithology and biostratigraphy.  As part of an investigation of the regional subsurface geologic framework in the Atlantic Coastal Plain Province, three deep cores were drilled by the U.S. Geological Survey at Pineora, Effingham County, Georgia; Cockspur Island, Chatham County, Georgia; and Palm Dunes, Beaufort County, South Carolina. The age of the UFAbased on calcareous nannofossil biostratigraphy ranges from early Oligocene to early Miocene in Pineora, late Eocene to late Oligocene in Cockspur Island, and late Eocene to questionably Miocene in Palm Dunes. Thin section analyses identified eleven unique microfacies across the study area and suggests that the sediments were most likely transported by oceanic currents at the time of deposition. Disconformities are identified from the Pineora and Palm Dunes cores and channel incision is documented at the top of the UFA in the Palm Dunes core. This study 1) documents how existing formation and time stratigraphic boundaries cross hydrogeologic units, 2) shows the complex geologic nature of the Upper Floridan aquifer across a relatively limited area, 3) sets forth a better understanding of how lateral and vertical changes in the lithologic units of the UFA affect permeability and porosity, and thus subsurface hydrologic flow, across the region, and 4) highlights the problems faced by legislators when implementing groundwater use regulations intended to slow salt water intrusion and drawdown.

Lakes as paleoseismic records in a seismically-active, low-relief area (Rieti Basin, central Italy)

Released March 29, 2019 09:47 EST

2019, Quaternary Science Reviews (211) 187-211

Claire Archer, Paula Noble, Michael R. Rosen, Leonardo Sagnotti, Fabio Fiorindo, Gianluca Piovesan, Scott Mensing, Alessandro Michetti

Small lakes in low relief areas are atypical candidates for studies on paleoseismicity, but their sediments can contain seismically induced event layers (seismites) generated through strong ground shaking, sediment transport, hydrological reorganization and/or changes in groundwater chemistry and flow. Lakes Lungo and Ripasottile are shallow lakes (<10m deep) located in the tectonically active Rieti Basin in the central Apennines, Italy, where strong normal faulting earthquakes (Mw 6.5 to 7.0) regularly occur. Sediment cores from these lakes provide paleoseismic indicators for the past ~1000 years. Sedimentological and geochemical analysis reveals four event layers identified in both lakes that correspond with documented large-scale earthquakes in 1298, 1349, 1639, and 1703 AD. Chronological correlation between earthquakes and possible seismites is reliable because of the unusually high resolution of sediment dating available for the studied cores. The common physical structure is a physically homogenous bed (homogenite) of re-suspended sediment consisting of a denser, high magnetic susceptibility (MS) clastic base, with organic matter concentrated above. Chemical signatures are associated with some event layers and may represent abrupt or transient shifts to a groundwater-dominated system, or permanent changes in groundwater flow and/or spring discharge. Excursions in δ13Corg may represent disruptions or changes in carbon source. Not all event layers show the same features, a result attributed to differences in seismic processes as well as the lake attributes, and anthropogenic modification. The observations made here may provide a new means of detecting paleoseismicity and may be applied to other low relief lakes in seismically active areas.

Assessing patterns of annual change to permafrost bluffs along the North Slope coast of Alaska using high-resolution imagery and elevation models

Released March 29, 2019 08:54 EST

2019, Geomorphology (336) 152-164

Ann E. Gibbs, Matt Nolan, Bruce M. Richmond, Alexander Snyder, Li Erikson

Coastal permafrost bluffs at Barter Island, on the North Slope, Beaufort Sea Coast of Alaska are among the most rapidly eroding along Alaska’s coast, having retreated up to 132 m between 1955 and 2015. Here we quantify rates and patterns of change over a single year using very-high resolution orthophotomosaics and co-registered surface elevation models derived from a survey-grade form of structure-from-motion photogrammetry from a fixed-wing, manned aircraft. The resulting elevation models were validated with over 10,000 ground check points and found that 95% agreed to within 20 cm, before accounting for real differences in the ground surface due to seasonality, vegetation, and checkpoint acquisition errors. This data set provides the most detailed and accurate measurements of coastal change to date along the Alaskan coast and the method is scaleable to more extensive coastlines. Between July 2014 and July 2015, the bluffs retreated an average of 1.3 m, and a maximum of 8.1 m, with an associated net volume loss of 38,100 ± 300 m3 (1.3 m3/m). This average retreat over this single year was slightly less than the 60-year mean rate of change of -1.5±0.1 m/yr, suggesting the 2014-2015 year represented relatively typical to slightly below average conditions. Most of the bluff material (70%) was lost during the 3 summer months (July to Sept) of 2014 and the remaining 30% between the late-summer and following winter-spring. The pattern of change was predominantly landward retreat of the top of the bluffs, removal of the debris apron and subsequent niching at the base of the bluffs during mid to late summer (July to Sept) followed by erosion of the bluff face and deposition of debris at the base of the bluff through the remainder of the year (Sept to the following July). Drivers of the observed change are likely a combination of thermal erosion on the bluff face throughout the summer and episodic thermo-mechanical removal of material, niching, and undercutting of the base associated with high-water levels driven by low-pressure storms and westerly winds. These patterns and high rates of change are believed to be broadly representative of coastal permafrost bluffs found along many high-latitude coastlines worldwide.

Effects of age and environment on stable carbon isotope ratios in tree rings of riparian Populus

Released March 28, 2019 15:22 EST

2019, Palaeogeography, Palaeoclimatology, Palaeoecology (524) 25-32

Jonathan M. Friedman, Craig A. Stricker, Adam Z Csank, Honghua Zhou

Stable carbon isotopes of riparian tree rings are enabling improved reconstruction of past climate variability, but this advance is limited by difficulty distinguishing the effects of tree age from those of climate. We investigated relative influence of age and climate trends in genus Populus, which dominates floodplain forests in Europe, Asia and North America. We related precipitation and river flow to annual variation in stable carbon isotope ratio (δ13C) in trees with a broad distribution of ages spanning two hundred years. On the floodplain of the lightly regulated Little Missouri River, North Dakota, USA, we examined a total of 845 rings from seven specimens of cottonwood tree (Populus deltoides W. Bartram ex Marshall ssp. monilifera [Aiton] Eckenwalder). Cottonwood δ13C decreased from pith to bark in whole wood, but this trend was almost completely eliminated in purified cellulose. The δ13C offset between whole wood and cellulose increased from pith to bark, consistent with trends of decreasing cellulose and increasing hemicellulose as a proportion of whole wood. While annual ring width was correlated with monthly precipitation from April through June, δ13C showed strong correlations only in June and July, suggesting that these complementary proxies allow resolution of seasonal variation in water availability. We conclude that past climate can be reconstructed from δ13C of purified cellulose from cottonwood without detrending for tree age.

HyCReWW: A hybrid coral reef wave and water level metamodel

Released March 28, 2019 15:19 EST

2019, Computers & Geosciences (127) 85-90

Ana C. Rueda, Laura Cagigal, Stuart Pearson, Jose Antolínez, Curt D. Storlazzi, Ap van Dongeren, Paula Camus, Fernando J. Mendez

Wave-induced flooding is a major coastal hazard on tropical islands fronted by coral reefs. The variability of shape, size, and physical characteristics of the reefs across the globe make it difficult to obtain a parameterization of wave run-up, which is needed for risk assessments. Therefore, we developed the HyCReWW metamodel to predict wave run-up under a wide range of reef morphometric and offshore forcing characteristics. Due to the complexity and high dimensionality of the problem, we assumed an idealized one-dimensional reef profile, characterized by seven primary parameters. XBeach Non-Hydrostatic was chosen to create the synthetic dataset, and Radial Basis Functions implemented in MATLAB® were chosen for interpolation. Results demonstrate the applicability of the metamodel to obtain fast and accurate results of wave run-up for a large range of intrinsic reef morphologic and extrinsic hydrodynamic forcing parameters, offering a useful tool for risk management and early warning systems.

Geology of the Hardeeville NW Quadrangle and parts of the Brighton and Pineland Quadrangles, Jasper County, South Carolina

Released March 28, 2019 14:00 EST

2019, Scientific Investigations Map 3424

Christopher S. Swezey, Arthur P. Schultz, William R. Doar III, Christopher P. Garrity, Christopher E. Bernhardt, Ernest A. Crider Jr., Lucy E. Edwards, John P. McGeehin

Introduction

This publication portrays the geology of the Hardeeville NW quadrangle and parts of the Brighton and Pineland quadrangles that are within Jasper County, South Carolina. The study area is located in the Atlantic Coastal Plain province, approximately 50 to 70 kilometers (km) inland from the coast. The data are compiled from geological field mapping, light detection and ranging (lidar) elevation data, cores, optically stimulated luminescence ages, radiocarbon ages, and biostratigraphic interpretations. Most of the study area is occupied by the valley of the Savannah River, and exposures of geologic units are very limited. Traditional geologic mapping in this area is difficult because of limited access, subdued topography, extensive swamps, and abundant vegetation.

The Savannah River flows predominantly southeast, and forms most of the border between the States of South Carolina and Georgia. The river is approximately 483 km long and has a total drainage area of approximately 15,850 square km. Although upstream tributaries drain the southeastern side of the Appalachian Blue Ridge province, the Savannah River begins in the Piedmont province and then flows across the Atlantic Coastal Plain province to the Atlantic Ocean. For much of its extent, the modern channel of the Savannah River is located on the southwestern side of the river valley, and the southwestern bank of the valley is the active cut bank. Within the study area, the valley of the Savannah River trends southeast and is relatively straight. The valley has relatively low relief, although the southwestern valley wall is steeper and has greater relief than the northeastern valley wall.

Elevations within the valley mostly range from 3 to 15 meters (m) above sea level, whereas elevations on the high terrace that forms the eastern margin of the Savannah River valley are 15 to 20 m above sea level. The width of the valley is 6 to 7 km in the northern part of the study area and expands to 10 to 12 km farther south. The modern river channel occupies the southwestern side of the valley, and some modern (active) creeks enter the river from the west. Sand hills and low-relief terraces are present to the east of the modern river channel, and the eastern side of the valley is characterized by abandoned meandering and linear channels. Fan-shaped deposits of sand and mud are present where relict (inactive) channels enter the eastern side of the valley. Abandoned meandering channels of low relief (<3 m) are also present to the east on the high terrace (>15 m elevation) that forms the eastern margin of the Savannah River valley. Within the study area, most of the Savannah River valley is covered by alluvial wetland community vegetation dominated by cypress and tupelo trees, although sand hills within the valley are covered by xeric sand community vegetation dominated by pine trees.

Wetland drying linked to variations in snowmelt runoff across Grand Teton and Yellowstone national parks

Released March 28, 2019 13:25 EST

2019, Science of the Total Environment (666) 1188-1197

Andrew M. Ray, Adam J. Sepulveda, Kathryn M. Irvine, Siri K.C. Wilmoth, David P. Thoma, Debra A. Patla

In Grand Teton and Yellowstone national parks wetlands offer critical habitat and play a key role in supporting biological diversity. The shallow depths and small size of many wetlands make them vulnerable to changes in climate compared with larger and deeper aquatic habitats. Here, we use a simple water balance model to generate estimates of biophysical drivers of wetland change. We then examine the relationship between wetland inundation status and four principal drivers (i.e., temperature, precipitation, evapotranspiration, and runoff) spanning varying meteorological conditions over an 8-year time series from Grand Teton and Yellowstone national parks. We found that a higher percentage of surveyed wetlands were dry in years characterized by lower snowmelt runoff. While runoff-based models were most supported, wetland drying was also related to variations in April to June precipitation and temperatures. Our work shows that wetland drying was widespread across both parks, but sub-regional variations were best described at the hydrologic subbasin-level. Documenting the varying responses of wetlands to meteorological drivers is a necessary first step to identifying which subbasins are most sensitive to recent change and contemplating how future change may alter the distribution of wetlands and their dependent taxa.

Establishing molecular methods to quantitatively profile gastric diet items of fish—Application to the invasive blue catfish (ictalurus furcatus)

Released March 28, 2019 11:30 EST

2019, Open-File Report 2019-1021

Deborah D. Iwanowicz, William B. Schill, Lakyn R. Sanders, Tim Groves, Mary C. Groves

Understanding the diet of invasive species helps researchers to more accurately assess the health, survivorship, growth, and stability of an invasive fish species, as well as their effects on native populations. Techniques capable of identifying multiple prey species from fish stomach contents have been developed. In this study, a multi-locus metabarcoding approach was used to identify fish and invertebrate prey in stomach samples of Ictalurus furcatus (blue catfish), which were collected from two sites on the Mattawomen Creek and Nanjemoy Creek in Maryland.

The mitochondrial 12S (mt12S) and mitochondrial 16S (mt16S) gene regions were sequenced and compared. First, a mock sample for each gene region was created with the pooled polymerase chain reaction product of known fish species, and quantities of the sample were used to determine efficacy of the amplicon. Results varied between gene regions analyzed. Then, when using the mt12S primers, next-generation sequencing determined that nine fish species were found at levels greater than 1 percent of the diet of blue catfish. The most common species were Perca flavescens (yellow perch) and Cyprinus carpio (common carp). The mt16S gene region analyses found 10 fish species at greater than 1 percent of the diet, which primarily included Orconectes limosus (spinycheek crayfish), Alosa pseudoharengus (alewife), and yellow perch. Partially digested eggs were identified using next-generation sequencing of yellow perch in two of the stomach samples, and a TaqMan® quantitative polymerase chain reaction (qPCR) assay was developed to more economically identify egg species in the future.

The yellow-perch-specific TaqMan® qPCR assay was tested using primers that were developed to detect a 154-base-pair amplicon in the mitochondrial control region. Consumption of yellow perch eggs indicates that blue catfish could potentially negatively affect young-of-year recruitment of this native sportfish. Analyses of two gene regions helped confirm the major prey of the fish sampled and allowed identification of fish species as prey that were not included in a database for the two gene regions. We concluded that the mitochondrial ribosomal-marker-based next-generation sequencing method is useful in determining the prey of fish species.

Improving eDNA yield and inhibitor reduction through increased water volumes and multi-filter isolation techniques

Released March 27, 2019 17:14 EST

2019, Scientific Reports (9)

Margaret Hunter, Jason Ferrante, Gaia Meigs-Friend, Amelia Ulmer

To inform management and conservation decisions, environmental DNA (eDNA) methods are used to detect genetic material shed into the water by imperiled and invasive species. Methodological enhancements are needed to reduce filter clogging, PCR inhibition, and false-negative detections when eDNA is at low concentrations. In the first of three simple experiments, we sought to ameliorate filter clogging from particulates and organic material through a scaled-up, multi-filter protocol. We combined four filters in a 5 mL Phenol-Chloroform-Isoamyl (PCI) procedure to allow for larger volumes of water (~1 L) to be filtered rapidly. Increasing the filtered water volume by four times resulted in 4.4X the yield of target DNA. Next, inhibition from organic material can reduce or block eDNA detections in PCR-based assays. To remove inhibitory compounds retained during eDNA isolation, we tested three methods to chemically strip inhibitors from eDNA molecules. The use of CTAB as a short-term (5–8 day) storage buffer, followed by a PCI isolation, resulted in the highest eDNA yields. Finally, as opposed to a linear relationship among increasing concentrations of filtered genomic eDNA, we observed a sharp change between the lower (70–280 ng) and higher (420–560 ng) amounts. This may be important for effectively precipitating eDNA during protocol testing.

Distribution and abundance of Least Bell’s Vireos (Vireo bellii pusillus) and Southwestern Willow Flycatchers (Empidonax traillii extimus) on the Middle San Luis Rey River, San Diego County, Southern California—2018 data summary

Released March 27, 2019 13:34 EST

2019, Data Series 1109

Lisa D. Allen, Barbara E. Kus

We surveyed for Least Bell’s Vireos (Vireo bellii pusillusvireo) and Southwestern Willow Flycatchers (Empidonax traillii extimus; flycatcher) along the San Luis Rey River, between College Boulevard in Oceanside and Interstate 15 in Fallbrook, California (middle San Luis Rey River), in 2018. Surveys were conducted from April 17 to July 16 (vireo) and from May 16 to July 27 (flycatcher). We found 148 vireo territories, at least 90 of which were occupied by pairs. Six additional transient vireos were detected. Vireos used six different habitat types in the survey area: mixed willow, willow-cottonwood, riparian scrub, willow-sycamore, upland scrub, and non-native habitat. Forty-one percent of the vireos were detected in habitat characterized as mixed willow, and 97 percent of the vireos were detected in habitat with greater than 50 percent native plant cover. Of 10 banded vireos detected in the survey area, 5 had been given full color-band combinations prior to 2018. Four other vireos with single (natal) federal bands were recaptured, identified, and color banded in 2018. One vireo with a single dark blue federal band, indicating that it was banded as a nestling on the lower San Luis Rey River, could not be recaptured for identification. 

One resident flycatcher and eight transient flycatchers of unknown subspecies were observed in the survey area in 2018. The resident flycatcher (male) was detected in a territory of mixed willow habitat with greater than 95 percent native plant cover. He was detected as a single male from May 24 to July 17, 2018, and no evidence of pairing or nesting was observed. The male flycatcher, detected with a single natal band, was recaptured, identified, and given a unique color combination in 2018. The male flycatcher was originally banded as a nestling on the middle San Luis Rey River in 2016. The eight transient flycatchers were detected from May 25 to June 8, 2018, in mixed willow riparian, willow-cottonwood, and riparian scrub habitat with greater than 95 percent native plant cover.

Measurement of long-term channel change through repeated cross-section surveys at bridge crossings in Alaska

Released March 27, 2019 10:38 EST

2019, Open-File Report 2019-1028

Karenth L. Dworsky, Jeffrey S. Conaway

The U.S. Geological Survey (USGS) has been working with Alaska Department of Transportation and Public Facilities (ADOT&PF) since 1993 to provide hydraulic assessments of scour for bridges throughout Alaska. The purpose of the program is to evaluate, monitor, and study streambed scour at bridges in Alaska; this includes surveying streambed elevations at regular intervals and monitoring real-time bed elevation changes. Over the duration of the scour program (1994–2017), repeated cross sections have been surveyed along the lengths of 76 bridges. Channel soundings are depth-from-bridge measurements on either the upstream or downstream side of a bridge. Flow, depth, and velocity dictated whether streambed elevations were measured using either USGS sounding weights on cable reels, weighted measuring tapes, or acoustic Doppler current profilers. The soundings were done on an annual basis at most sites. In addition to annual soundings, channel soundings were made during floods or periods of scour. Results show that general scour can be uniform or non-uniform across the channel. The magnitude and distribution of scour across the channel are influenced by several factors that include streambed sediment type, degree of channel contraction at the bridge crossing, influence of instream structures, and bridge pier location and alignment. The data collected from the repeat soundings can be used to identify long-term aggradation or degradation of the streambed, as well as seasonal changes in streambed elevations.

Laboratory for Infectious Disease and the Environment (LIDE)

Released March 26, 2019 16:45 EST

2019, Fact Sheet 2018-3079

Joel P. Stokdyk, Jennifer L. Bruce, Tucker R. Burch, Susan K. Spencer, Aaron Firnstahl, Mark A. Borchardt

The Laboratory for Infectious Disease and the Environment (LIDE) studies the occurrence, fate and transport, and health effects of human and agricultural zoonotic pathogens in the environment. The LIDE is an interagency collaborative effort between the U.S. Geological Survey and the U.S. Department of Agriculture-Agricultural Research Service that conducts research to inform decision makers and advance scientific knowledge. The LIDE collaborates with public agencies and academic researchers in partnerships and works cooperatively or independently on all aspects of the research process. The LIDE's laboratory capabilities include quantitative polymerase chain reaction and pathogen culture.

Tampa Bay Ocean and Coastal Acidification Monitoring Quality Assurance Project Plan

Released March 26, 2019 15:30 EST

2019, Open-File Report 2019-1003

Kimberly K. Yates, Christopher S. Moore, Nathan H. Goldstein, Edward T. Sherwood

Coastal acidification caused by eutrophication, freshwater inflow, and upwelling is already affecting many estuaries worldwide and can be exacerbated by ocean acidification that is caused by increasing carbon dioxide in the atmosphere. Effective management, mitigation, and (or) adaptation to the effects of coastal and ocean acidification require careful monitoring of the resulting changes in seawater chemistry. Local, regional, and national agencies and institutions organizing acidification-monitoring and research efforts work toward standardizing data collection and reporting protocols so that data can be shared and compared across regions and synthesized into national assessments. This document describes a Quality Assurance Project Plan for the collection and reporting of seawater chemical and physical data using standardized methods and published best practices relevant for monitoring coastal and ocean acidification. The plan specifically addresses procedures for a joint partnership, the Tampa Bay Ocean and Coastal Acidification Monitoring project, conducted by the U.S. Geological Survey, the U.S. Environmental Protection Agency, and the Tampa Bay Estuary Program in the Tampa Bay estuary, Florida. The plan describes recommended procedures for project organization, sampling process design and methods, data-quality objectives and criteria, data validation and management procedures, and project deliverables.

Radiometric calibration of a non-imaging airborne spectrometer to measure the Greenland ice sheet surface

Released March 26, 2019 10:42 EST

2019, Atmospheric Measurement Techniques (12) 1913-1933

Christopher J. Crawford, Jeannette van den Bosch, Kelly M. Brunt, Milton G. Hom, John W. Cooper, David J. Harding, James J. Butler, Philip W. Dabney, Thomas A. Neumann, Craig S. Cleckner, Thorsten Markus

Methods to radiometrically calibrate a non-imaging airborne visible-to-shortwave infrared (VSWIR) spectrometer to measure the Greenland ice sheet surface are presented. Airborne VSWIR measurement performance for bright Greenland ice and dark bare rock/soil targets is compared against the MODerate resolution atmospheric TRANsmission (MODTRAN®) radiative transfer code (version 6.0), and a coincident Landsat 8 Operational Land Imager (OLI) acquisition on 29 July 2015 during an in-flight radiometric calibration experiment. Airborne remote sensing flights were carried out in northwestern Greenland in preparation for the Ice, Cloud, and land Elevation Satellite 2 (ICESat-2) laser altimeter mission. A total of nine science flights were conducted over the Greenland ice sheet, sea ice, and open-ocean water. The campaign's primary purpose was to correlate green laser pulse penetration into snow and ice with spectroscopic-derived surface properties. An experimental airborne instrument configuration that included a nadir-viewing (looking downward at the surface) non-imaging Analytical Spectral Devices (ASD) Inc. spectrometer that measured upwelling VSWIR (0.35 to 2.5 µm) spectral radiance (Wm2sr1µm1) in the two-color Slope Imaging Multi-polarization Photon-Counting Lidar's (SIMPL) ground instantaneous field of view, and a zenith-viewing (looking upward at the sky) ASD spectrometer that measured VSWIR spectral irradiance (W m−2 nm−1) was flown. National Institute of Standards and Technology (NIST) traceable radiometric calibration procedures for laboratory, in-flight, and field environments are described in detail to achieve a targeted VSWIR measurement requirement of within 5 % to support calibration/validation efforts and remote sensing algorithm development. Our MODTRAN predictions for the 29 July flight line over dark and bright targets indicate that the airborne nadir-viewing spectrometer spectral radiance measurement uncertainty was between 0.6 % and 4.7 % for VSWIR wavelengths (0.4 to 2.0 µm) with atmospheric transmittance greater than 80 %. MODTRAN predictions for Landsat 8 OLI relative spectral response functions suggest that OLI is measuring 6 % to 16 % more top-of-atmosphere (TOA) spectral radiance from the Greenland ice sheet surface than was predicted using apparent reflectance spectra from the nadir-viewing spectrometer. While more investigation is required to convert airborne VSWIR spectral radiance into atmospherically corrected airborne surface reflectance, it is expected that airborne science flight data products will contribute to spectroscopic determination of Greenland ice sheet surface optical properties to improve understanding of their potential influence on ICESat-2 measurements.

Interactive mapping of nonindigenous species in the Laurentian Great Lakes

Released March 26, 2019 08:56 EST

2019, Management of Biological Invasions (10) 192-199

Joseph P. Smith, El K. Lower, Felix A. Martinez, Catherine M. Riseng, Lacey A. Mason, Edward S. Rutherford, Matthew E. Neilson, Pam L. Fuller, Kevin E. Wehrly, Rochelle A. Sturtevant

Nonindigenous species pose significant risks to the health and integrity of ecosystems around the world. Tracking and communicating the spread of these species has been of interest to ecologists and environmental managers for many years, particularly in the bi-national Laurentian Great Lakes of North America. In this paper, we introduce the Great Lakes Aquatic Nonindigenous Species Information System (GLANSIS) Map Explorer. The Map Explorer provides access to records of documented nonindigenous species and their spatial distributions. Users may view the distributions of well-known nonindigenous species (such as zebra mussels) as well as perform custom queries. Additional map layers allow users to compare the distribution of nonindigenous species to environmental conditions. This tool serves to communicate knowledge to diverse stakeholder groups and to enable further in-depth research on nonindigenous species.

Undocumented late 18th- to early 19th-century volcanic eruptions in the Southwest Rift Zone of Kīlauea Volcano, Hawai‘i

Released March 25, 2019 08:34 EST

2019, Scientific Investigations Report 2019-5010

Richard W. Hazlett, Tim R. Orr, Steve P. Lundblad

The historical record of volcanic activity at Kīlauea Volcano on the Island of Hawaiʻi begins with the phreatomagmatic blasts of 1790. Three decades later, in 1823, the first party of non-Hawaiian visitors, organized by the English Reverend William Ellis, reached Kīlauea’s summit. A detailed narrative by Ellis includes an account of an eruption in Kīlauea’s Southwest Rift Zone that occurred shortly before his visit. In the absence of other source materials, the interval between the eruptions of 1790 and 1823 has been overlooked by geologists working at Kīlauea, with the presumption that little if anything took place volcanically outside of the summit caldera during that time. Careful stratigraphic observations combined with radiocarbon dating demonstrate that during these years a set of Southwest Rift Zone eruptions took place, including two that were long-lasting (weeks to months). Inclusion of these events gives a more complete historical (post-1790) record for Kīlauea and a better understanding of its eruptive behavior.

Invasive buffelgrass detection using high-resolution satellite and UAV imagery on Google Earth Engine

Released March 23, 2019 13:29 EST

2019, Remote Sensing in Ecology and Conservation

Kaitlyn Elkind, Temuulen T. Sankey, Seth M. Munson, Clare E. Aslan

 Methods to detect and monitor the spread of invasive grasses are critical to avoid ecosystem transformations and large economic costs. The rapid spread of non-native buffelgrass (Pennisetum ciliare) has intensified fire risk and is replacing fire intolerant native vegetation in the Sonoran Desert of the southwestern U.S. Coarse-resolution satellite imagery has had limited success in detecting small patches of buffelgrass, while ground-based and aerial survey methods are often cost prohibitive. To improve detection, we trained 2-m resolution WorldView-2 satellite imagery with 12-cm resolution unmanned aerial vehicle (UAV) imagery and classified buffelgrass on Google Earth Engine, a cloud computing platform, using Random Forest (RF) models in Saguaro National Park, Arizona, USA. Our classification models had an average overall accuracy of 94% and producer’s accuracies of 54-75% for buffelgrass. We detected a 2.92 km2 area of buffelgrass in the eastern Rincon Mountain District (1.07% of the total area) and a 0.46 km2 area (0.46% of the total area) in the western Tucson Mountain District of Saguaro National Park. Buffelgrass cover was significantly greater in the Sonoran Paloverde-Mixed Cacti Desert Scrub vegetation type, on poorly developed Entisols and Inceptisol soils, and on south-facing topographic aspects compared to other areas. When we applied our classification model across herbicide control treatments within the park, we observed both lower and higher amounts of buffelgrass in treated relative to untreated areas. Our results demonstrate that high resolution imagery can improve on previous attempts to detect and classify buffelgrass and indicate potential areas where the invasive grass might spread. The methods demonstrated in this study could be employed by land managers as a low-cost strategy to identify priority areas for control efforts and continued monitoring.

Regeneration of Metrosideros polymorpha forests in Hawaii after landscape‐level canopy dieback

Released March 22, 2019 15:47 EST

2019, Journal of Vegetation Science (30) 146-155

Linda Mertelmeyer, James D. Jacobi, Dieter Mueller-Dombois, Kevin W. Brinck, Hans Juergen Boehmer

Questions

(a) Have Metrosideros polymorpha trees become re‐established in Hawaiian forests previously impacted by canopy dieback in the 1970s? (b) Has canopy dieback expanded since the 1970s? (c) Can spatial patterns from this dieback be correlated with habitat factors to model future dieback in this area?

Study Site

An 83,603 ha study area on the eastern slopes of Mauna Loa and Mauna Kea volcanoes on the island of Hawaii, USA.

Methods

We analyzed very‐high‐resolution imagery to assess status of Metrosideros polymorphaforests across the eastern side of the island of Hawaii. We generated 1,170 virtual vegetation plots with a 100‐m radius; 541 plots in areas mapped in 1977 with trees dead or mostly defoliated (dieback), and 629 plots in adjacent wet forest habitat, previously mapped as non‐dieback condition. In each plot we estimated the frequency of M. polymorpha trees that were dead or mostly defoliated, and the frequency of trees with healthy crowns. These results were combined with habitat data to produce a spatial model depicting probability of canopy dieback within the study area.

Results

Seventy‐nine percent of plots mapped in 1977 in dieback condition recovered their canopy and were now considered in non‐dieback condition. Ninety‐one percent of plots in previous non‐dieback areas were found to still have a healthy M. polymorpha canopy in 2015. A spatial model allowed us to identify areas within the study area with high, medium, and low probability of experiencing this same type of canopy dieback in the future.

Conclusions

Most former dieback areas mapped within the study area in 1977 now show recovery of the tree canopy through growth of new cohorts of young M. polymorpha trees. This suggests these forest communities are resilient to this type of canopy loss and tree death so long as other factors do not disrupt the natural regeneration process.

Confronting uncertainty: Contributions of the wildlife profession to the broader scientific community

Released March 22, 2019 15:32 EST

2019, Journal of Wildlife Management (83) 519-533

James D. Nichols

Most wildlife professionals are engaged in 1 or both of 2 basic endeavors: science and management. These endeavors are a focus of many other disciplines, leading to widespread sharing of general methodologies. Wildlife professionals have appropriately borrowed and assimilated many methods developed primarily in other disciplines but have also led the development of one class of quantitative methods, those that confront and incorporate uncertainty. Uncertainty arises in counts of focal entities, for which wildlife professionals have developed effective methods to deal with the common problems of nondetection and misclassification. These methods have been borrowed by disciplines as varied as paleobiology, medicine, human epidemiology, industrial quality control, military target acquisition, remote sensing, and human census. Uncertainty also arises in the modeling of those counts, specifically the observation and ecological processes that generated them. Wildlife professionals recognized the fundamental importance of model selection and rapidly assimilated methods for selecting the most appropriate model for a given data set. These methods for dealing with uncertainty inherent to counting and modeling are critical to the conduct of science and management. Wildlife professionals have developed additional methods for incorporating uncertainty in the accumulation of knowledge and the development of optimal decisions in an environment of learning. In some cases, professionals in other disciplines are using methods developed and popularized in the wildlife profession, but there is much potential for greater use. In this essay, I describe these areas of wildlife leadership, document their assimilation by other disciplines, and emphasize the potential for more interdisciplinary use of these methods. 

Environmental DNA as a tool to help inform zebra mussel, Dreissena polymorpha, management in inland lakes

Released March 22, 2019 15:30 EST

2019, Management of Biological Invasions (10) 96-110

Jon J. Amberg, Christopher M. Merkes, Wendylee Stott, Christopher B. Rees, Richard A. Erickson

Zebra mussels (Dreissena polymorpha) are an aquatic invasive species that plague much of North America and are difficult to impossible to eradicate once they become established. Therefore, prevention and monitoring are key elements in the control of these organisms. Traditional microscopy is commonly used in monitoring but requires the presence of larval veligers. This limits the times when resource managers can monitor for the presence in northern lakes. A new monitoring tool, environmental DNA (eDNA), may allow for a more efficient and cost-effective monitoring program for zebra mussels. We developed and tested an environmental DNA assay in the fall and spring for zebra mussels in two Minnesota lakes, one heavily infested and another newly infested. We found that DNA copy numbers tended to be higher near the lake bottom and DNA was more concentrated in softer substrates. We also found that the amount of zebra mussel DNA sampling in winter resulted in similar results to when sampled in fall. This suggests that one could collect and analyze eDNA for zebra mussels during winter months to help inform future efforts in monitoring and control.

North-south dipole in winter hydroclimate in the western United States during the last deglaciation

Released March 22, 2019 15:27 EST

2019, Scientific Reports (9) 1-12

Adam M. Hudson, Benjamin J. Hatchett, Jay Quade, Douglas P. Boyle, Scott D. Bassett, Guleed Ali, Marie G. De los Santos

During the termination of the last glacial period the western U.S. experienced exceptionally wet conditions, driven by changes in location and strength of the mid-latitude winter storm track. The distribution of modern winter precipitation is frequently characterized by a north-south wet/dry dipole pattern, controlled by interaction of the storm track with ocean-atmosphere conditions over the Pacific and Atlantic Oceans. Here we show that a dipole pattern of similar geographic extent persisted and switched sign during millennial-scale abrupt climate changes of the last deglaciation, based on a new lake level reconstruction for pluvial Lake Chewaucan (northwestern U.S.), and a compilation of regional paleoclimate records. This suggests the dipole pattern is robust, and one mode may be favored for centuries, thereby creating persistent contrasting wet/dry conditions across the western U.S. The TraCE-21k climate model simulation shows an equatorward enhancement of winter storm track activity in the northeastern Pacific, favoring wet conditions in southwestern U.S. during the second half of Heinrich Stadial 1 (16.1–14.6 ka) and consistent with paleoclimate evidence. During the Bølling/Allerød (14.6–12.8 ka), the northeastern Pacific storm track contracted poleward, consistent with wetter conditions concentrated poleward toward the northwest U.S.

The effectiveness of non-native fish removal techniques in freshwater ecosystems: a systematic review

Released March 22, 2019 13:44 EST

2019, Environmental Reviews (27) 71-94

Trina Rytwinski, Jessica J. Taylor, Lisa A. Donaldson, J. Robert Britton, David R. Browne, Robert E. Gresswell, Mark Lintermans, Kent A. Prior, Marlow G. Pellatt, Chantal Vis, Steven J. Cooke

In aquatic systems, biological invasions can result in adverse ecological effects. Management techniques available for non-native fish removal programs (including eradication and population size control) vary widely, but include chemicals, harvest regimes, physical removal, or biological control. For management agencies, deciding on what non-native fish removal program to use has been challenging because there is little reliable information about the relative effectiveness of these measures in controlling or eradicating non-native fish. We conducted a systematic review, including a critical appraisal of study validity, to assess the effectiveness of different non-native fish removal methods, and to identify the factors that influence the overall success rate of each type of method. We found 95 relevant studies, generating 158 data sets. The evidence base was dominated by poorly documented studies with inadequate experimental designs (76% of removal projects). When the management goal was non-native fish eradication, chemical treatments were relatively successful (antimycin 75%; rotenone 89%) compared to other interventions. Electrofishing and passive removal measure studies indicated successful eradication was possible (58% each respectively) but required intensive effort and multiple treatments over a number of years. Of these studies with sufficient information, electrofishing had the highest success for population size control (56% of data sets). Overall, inadequate data quality and completeness severely limited our ability to make strong conclusions about the relationships between non-native fish abundance and different methods of eradication and population control, and the factors influencing the overall success rate of each method. Our review highlights that there is considerable scope for improving our evaluations of non-native fish removal methods. It is recommended that programs should have explicitly stated objectives, better data reporting, and study designs that (when possible and appropriate) incorporate replicated and controlled investigations with rigorous, long-term quantitative monitoring. Future research on the effectiveness of non-native fish removal methods should focus on: (1) the efficacy of existing or potentially new removal measures in larger, more complex environments; (2) a broader range of removal measures in general, and (3) phenotypic characteristics of individual fish within a population that fail to be eradicated or controlled.

Pesticides and pollinators: A socioecological synthesis

Released March 22, 2019 10:58 EST

2019, Science of the Total Environment (662) 1012-1027

Douglas B. Sponsler, Christina M. Grozinger, Claudia Hitaj, Maj Rundlof, Cristina Botias, Aimee Code, Eric V. Lonsdorf, Andony P. Melthapoulos, David J. Smith, Sainath Suryanarayanan, Wayne E. Thogmartin, Neal M. Williams, Minghua Zhang, Margaret R. Douglas

The relationship between pesticides and pollinators, while attracting no shortage of attention from scientists, regulators, and the public, has proven resistant to scientific synthesis and fractious in matters of policy and public opinion. This is in part because the issue has been approached in a compartmentalized and intradisciplinary way, such that evaluations of organismal pesticide effects remain largely disjoint from their upstream drivers and downstream consequences. Here, we present a socioecological framework designed to synthesize the pesticide-pollinator system and inform future scholarship and action. Our framework consists of three interlocking domains-pesticide use, pesticide exposure, and pesticide effects–each consisting of causally linked patterns, processes, and states. We elaborate each of these domains and their linkages, reviewing relevant literature and providing empirical case studies. We then propose guidelines for future pesticide-pollinator scholarship and action agenda aimed at strengthening knowledge in neglected domains and integrating knowledge across domains to provide decision support for stakeholders and policymakers. Specifically, we emphasize (1) stakeholder engagement, (2) mechanistic study of pesticide exposure, (3) understanding the propagation of pesticide effects across levels of organization, and (4) full-cost accounting of the externalities of pesticide use and regulation. Addressing these items will require transdisciplinary collaborations within and beyond the scientific community, including the expertise of farmers, agrochemical developers, and policymakers in an extended peer community.

UAV-based measurements of spatio-temporal concentration distributions of fluorescent tracers in open channel flows

Released March 22, 2019 10:54 EST

2019, Advances in Water Resources (127) 76-88

Donghae Baek, Il Won Seo, Jun Song Kim, Jonathan M. Nelson

A new method of unmanned aerial vehicle (UAV)-based tracer tests using RGB (red, green, blue) images was developed in order to acquire the spatio-temporal concentration distribution of tracer clouds in open channel flows. Tracer tests using Rhodamine WT were conducted to collect the RGB images using a commercial digital camera mounted on a UAV, and the concentration of Rhodamine WT using in-situ fluorometric probes. The correlation analysis showed that the in-situmeasured concentrations of Rhodamine WT were strongly correlated with the digital number (DN) of the RGB images, even though the response of DN to the concentration was spatially heterogeneous. The empirical relationship between the DN values and the Rhodamine WT concentration data was estimated using artificial neural network (ANN) models. The trained ANN models, which consider the effect of water depth and river bed, accurately retrieved the detailed spatio-temporal concentration distributions of all study areas that had an R2 higher than 0.9. The acquired spatio-temporal concentration distributions by the proposed method based on the UAV images gave general as well as detailed views of the tracer cloud moving dynamically in open channel flows that cannot be easily observed using conventional in-situ measurements.

Fish culling reduces tapeworm burden in Arctic charr by increasing parasite mortality rather than by reducing density‐dependent transmission

Released March 22, 2019 10:52 EST

2019, Journal of Applied Ecology

Eirik H. Henriksen, Andre Frainer, Rune Knudsen, Roar Kristoffersen, Armand M. Kuris, Kevin D. Lafferty, Per-Arne Amundsen

  1. Two common Dibothriocephalus (formerly Diphyllobothrium) tapeworm species were significantly reduced by experimental culling of their fish host Arctic charr (Salvelinus alpinus) in a subarctic lake.

  2. Between 1984 and 1991, funnel traps were used to cull ~35 metric tons of Arctic charr, reducing charr density by ~80%. As charr densities decreased, tapeworm prevalence and then intensity also declined over the following three decades, with D. dendriticus (formerly dendriticum) responding faster than D. ditremus (formerly ditremum). The two main hypotheses for how culling a host can decrease parasitism are reductions in parasite transmission due to reduced host density and reductions in parasite survival through increases in host mortality rates.

  3. We found little evidence that charr density was the main driver for reduced parasite transmission. Instead, decreased survivorship in charr, initially, through fishing‐induced changes in charr age structure, and later through increased predation rates by brown trout, led to increased parasite mortality. Although brown trout, which increased significantly after fish culling, are also hosts, they are often too big for the final host birds to eat, thus becoming parasite sinks.

  4. Synthesis and applications. Fish populations with heavy parasite burdens constitute a management problem. Our results show how fish culling can indirectly reduce transmitted parasites through increased parasite mortality. Managing overcrowded fish populations by culling can produce two desirable outcomes: an increase in fish growth rates and reduced parasite burdens.

Scale‐dependent effects of isolation on seasonal patch colonisation by two Neotropical freshwater fishes

Released March 22, 2019 10:50 EST

2019, Ecology of Freshwater Fish (28) 274-284

Jerry Penha, Karlo Y. P. Hakamada, James E. Hines, James D. Nichols

The metapopulation paradigm has been central to improve the conservation and management of natural populations. However, despite the large number of studies on metapopulation dynamics, the overall support for the relationships on which the paradigm is based has not been strong. Here, we studied the occupancy dynamics of two Neotropical fishes (i.e., Pimelodella gracilis and Leporinus friderici) to investigate two fundamental premises of the metapopulation paradigm, that is, that isolation and area/habitat quality affect colonisation and extinction probabilities in predictable ways. In order to do this, we used a modification of occupancy models that allows modelling the probability of a site's occupancy as a function of the occupancy of its neighbourhood. We found a weak positive effect of neighbourhood occupancy on Pgracilis colonisation, which is consistent with the propagule rain metapopulation, that is, colonists arriving from outside the studied system. However, we found a strong negative neighbourhood effect on extinction probability, suggesting that declining populations from stream sections are rescued from extinction by neighbouring patches. In contrast, the effect of neighbourhood occupancy on the metapopulation dynamics of L. friderici was in the opposite direction, affecting positively colonisation but not affecting extinction rates, which is consistent with the classical metapopulation model. In addition, the occupancy dynamics of both species were affected by water velocity. To our knowledge, this is the first study to link directly dispersal to local population dynamics in Neotropical fishes, and one of the few studies doing inferences on spatial population dynamics based on direct estimates of neighbourhood occupancy.

Southern sea otter (Enhydra lutris nereis) population biology at Big Sur and Monterey, California --Investigating the consequences of resource abundance and anthropogenic stressors for sea otter recovery

Released March 22, 2019 08:26 EST

2019, Open-File Report 2019-1022

M. Tim Tinker, Joseph A. Tomoleoni, Benjamin P. Weitzman, Michelle Staedler, Dave Jessup, Michael J. Murray, Melissa Miller, Tristan Burgess, Lizabeth Bowen, A. Keith Miles, Nicole Thometz, Lily Tarjan, Emily Golson, Francesca Batac, Erin Dodd, Eva Berberich, Jessica Kunz, Gena Bentall, Jessica Fujii, Teri Nicholson, Seth Newsome, Ann Melli, Nicole LaRoche, Holly MacCormick, Andy Johnson, Laird Henkel, Chris Kreuder-Johnson, Pat Conrad

The range of the southern sea otter (Enhydra lutris nereis) spans most of the central California coast from Half Moon Bay to Gaviota. Some coastal areas within this range are heavily developed and highly impacted by humans, while other areas are wild and largely pristine. Determining the relative importance of food resource abundance, environmental conditions, and anthropogenic increases in pathogens and pollutants to population change in sea otters is critical to understanding limitations to population growth. To investigate the causal links between the sluggish population growth of sea otters in central California and factors that could be driving variation in survival and reproduction, we designed a study to compare two distinct subpopulations—one in an area of low human impact (Big Sur) and one in an area of high human impact (Monterey). Between 2008 and 2011, the U.S. Geological Survey and collaborators conducted a telemetry-based study of sea otters at these two locations. The results of this study were not consistent with the hypothesis that sea otters adjacent to human population centers (Monterey) experience higher exposure to pollutants and pathogens than those in lower impacted areas (Big Sur). In fact, based on serological analysis, female sea otters from Big Sur showed higher exposure rates to Toxoplasma gondii than did female otters from Monterey, while domoic acid exposure appeared to be similar at both sites. Gene expression (specifically transcription) analysis did not indicate any consistent differences between the two populations that would have suggested a response to pathogen or toxin exposure, although there were temporal changes in gene transcription for sea otters at Big Sur following potential exposure to run-off from wildfires that occurred during the study. Together, these metrics suggest that variation in exposure to environmental stressors occurred, but patterns were not clearly attributable to differences in human population densities or land-use patterns. When compared to Monterey, sea otters in Big Sur spent more time feeding, had a higher degree of dietary specialization, were in poorer body condition, and had lower survival rates (both pups and adults). Together, these metrics suggest that otters at Big Sur had greater nutritional stress, consistent with lower per-capita resource abundance. Overall, study results indicate that density-dependent population regulation, mediated by per-capita resource abundance, is the most significant factor currently limiting population growth in the center part of the range. Additionally, spatial and temporal variation in environmental and anthropogenic stressors also can affect sea otter health, although patterns of variation are complex and are not simply a function of proximity to human populations. We also found that exposure to environmental stressors (either natural or anthropogenic in origin) often is associated with resource limitation. Finally, our results indicate that sea otter populations are structured at relatively small spatial scales, and the processes that regulate population abundance (including density-dependent resource abundance) also occur at these smaller, more local scales.

Stream metabolism increases with drainage area and peaks asynchronously across a stream network

Released March 21, 2019 16:36 EST

2019, Aquatic Sciences (81) 1-17

Francine H. Mejia, Alexander K. Fremier, Joseph R. Benjamin, J. Ryan Bellmore, Adrianne Z. Grimm, Grace A. Watson, Michael Newsom

Quantifying the spatial and temporal dynamics of stream metabolism across stream networks is key to understanding carbon cycling and stream food web ecology. To better understand intra-annual temporal patterns of gross primary production (GPP) and ecosystem respiration (ER) and their variability across space, we continuously measured dissolved oxygen and modeled stream metabolism for an entire year at ten sites across a temperate river network in Washington State, USA. We expected GPP and ER to increase with stream size and peak during summer and autumn months due to warmer temperatures and higher light availability. We found that GPP and ER increased with drainage area and that only four sites adhered to our expectations of summer peaks in GPP and autumn peaks in ER while the rest either peaked in winter, spring or remained relatively constant. Our results suggest the spatial arrangement and temporal patterns of discharge, temperature, light and nutrients within watersheds may result in asynchronies in GPP and ER, despite similar regional climatic conditions. These findings shed light on how temporal dynamics of stream metabolism can shift across a river network, which likely influence the dynamics of carbon cycling and stream food webs at larger scales.

Evidence for non-steady-state carbon emissions from snow-scoured alpine tundra

Released March 21, 2019 14:11 EST

2019, Nature Communications (10)

John F. Knowles, Peter D. Blanken, Corey Lawrence, Mark W. Williams

High-latitude warming is capable of accelerating permafrost degradation and the decomposition of previously frozen carbon. The existence of an analogous high-altitude feedback, however, has yet to be directly evaluated. We address this knowledge gap by coupling a radiocarbon-based model to 7 years (2008–2014) of continuous eddy covariance data from a snow-scoured alpine tundra meadow in Colorado, USA, where solifluction lobes are associated with discontinuous permafrost. On average, the ecosystem was a net annual source of 232 ± 54 g C m−2 (mean ± 1 standard deviation) to the atmosphere, and respiration of relatively radiocarbon-depleted (i.e., older) substrate contributes to carbon emissions during the winter. Given that alpine soils with permafrost occupy 3.6 × 106 km2 land area and are estimated to contain 66.3 Pg of soil organic carbon (4.5% of the global pool), this scenario has global implications for the mountain carbon balance and corresponding resource allocation to lower elevations.

Cryptosporidium incidence and surface water influence of groundwater supplying public water systems in Minnesota, USA

Released March 21, 2019 13:08 EST

2019, Environmental Science & Technology

Joel P. Stokdyk, Susan K. Spencer, James F. Walsh, Jane R. de Lambert, Aaron D. Fimstahl, Anita C. Anderson, Lih-in W. Rezania, Mark A. Borchardt

Regulations for public water systems (PWS) in the U.S. consider Cryptosporidium a microbial contaminant of surface water supplies. Ground- water is assumed free of Cryptosporidium unless surface water is entering supply wells. We determined the incidence of Cryptosporidium in PWS wells varying in surface water influence. Community and noncommunity PWS wells (n = 145) were sampled (n = 964) and analyzed for Cryptosporidium by qPCR and immunofluorescence assay (IFA). Surface water influence was assessed by stable isotopes and the expert judgment of hydrogeologists using site-specific data. Fifty-eight wells (40%) and 107 samples (11%) were Cryptosporidium- positive by qPCR, and of these samples 67 were positive by IFA. Cryptosporidium concentrations measured by qPCR and IFA were significantly correlated (p < 0.001). Cryptosporidium incidence was not associated with surface water influence as assessed by stable isotopes or expert judgment. We successfully sequenced 45 of the 107 positive samples to identify species, including C. parvum (41), C. andersoni (2), and C. hominis (2), and the predominant subtype was C. parvum IIa A17G2R1. Assuming USA regulations for surface water-supplied PWS were applicable to the study wells, wells positive for Cryptosporidium by IFA would likely be required to add treatment. Cryptosporidium is not uncommon in groundwater, even when surface water influence is absent.

Relative abundance and molecular evolution of Lake Sinai Virus (Sinaivirus) clades

Released March 21, 2019 11:08 EST

2019, PeerJ (7)

Robert S. Cornman

Lake Sinai Viruses (Sinaivirus) are commonly detected in honey bees (Apis mellifera) but no disease phenotypes or fitness consequences have yet been demonstrated. This viral group is genetically diverse, lacks obvious geographic structure, and multiple lineages can co-infect individual bees. While phylogenetic analyses have been performed, the molecular evolution of LSV has not been studied extensively. Here, I use LSV isolates from GenBank as well as contigs assembled from honey bee Sequence Read Archive (SRA) accessions to better understand the evolutionary history of these viruses. For each ORF, substitution rate variation, codon usage, and tests of positive selection were evaluated. Outlier regions of high or low diversity were sought with sliding window analysis and the role of recombination in creating LSV diversity was explored. Phylogenetic analysis consistently identified two large clusters of sequences that correspond to the current LSV1 and LSV2 nomenclature, however lineages sister to LSV1 were the most frequently detected in honey bee SRA accessions. Different expression levels among ORFs suggested the occurrence of subgenomic transcripts. ORF1 and RNA-dependent RNA polymerase had higher evolutionary rates than the capsid and ORF4. A hypervariable region of the ORF1 protein-coding sequence was identified that had reduced selective constraint, but a site-based model of positive selection was not significantly more likely than a neutral model for any ORF. The only significant recombination signals detected between LSV1 and LSV2 initiated within this hypervariable region, but assumptions of the test (single-frame coding and independence of substitution rate by site) were violated. LSV codon usage differed strikingly from that of honey bees and other common honey-bee viruses, suggesting LSV is not strongly co-evolved with that host. LSV codon usage was significantly correlated with that of Varroa destructor, however, despite the relatively weak codon bias exhibited by the latter. While codon usage between the LSV1 and LSV2 clusters was similar for three ORFs, ORF4 codon usage was uncorrelated between these clades, implying rapid divergence of codon use for this ORF only. Phylogenetic placement and relative abundance of LSV isolates reconstructed from SRA accessions suggest that detection biases may be over-representing LSV1 and LSV2 in public databases relative to their sister lineages.

Hydraulic conductivity estimates from slug tests in the Big Sioux aquifer near Sioux Falls, South Dakota

Released March 21, 2019 09:45 EST

2019, Scientific Investigations Report 2019-5013

William G. Eldridge, Colton J. Medler

Hydraulic conductivity estimates were made for 15 observation wells using slug-out (rising-head) tests in the Big Sioux aquifer near Sioux Falls, South Dakota, as part of a cooperative study with the City of Sioux Falls to characterize the hydrogeology and the extent of the Big Sioux aquifer north of the city. Well and aquifer data were collected from field measurements and drillers’ logs. Multiple slug tests were completed at each observation well with a transducer to record the change in water level and a U.S. Geological Survey standard mechanical slug to displace the well’s water column. In total, 110 slug-out test trials were completed among the 15 observation wells. Hydraulic conductivity was estimated by curve fitting with AQTESOLV Pro version 4.50.002. Hydraulic conductivity estimates ranged from 64 to 379 feet per day (ft/d). The mean, standard deviation, and median hydraulic conductivity for the 110 slug-out test trials were 171 ft/d, 73 ft/d, and 157 ft/d, respectively. The mean hydraulic conductivity calculated for each well ranged from 88 to 270 ft/d, the standard deviation ranged from 7 to 66 ft/d, and the median hydraulic conductivity ranged from 86 to 256 ft/d.