Skip to main content
U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Https

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Publications recently added to the Pubs Warehouse

(500 records max)
DOI/GTN-P climate and active-layer data acquired in the National Petroleum Reserve-Alaska and the Arctic National Wildlife Refuge, 1998-2019

Released June 11, 2021 12:00 EST

2018, Data Series 1092

Frank E. Urban, Gary D. Clow

This report provides data collected by the climate monitoring array of the U.S. Department of the Interior on Federal lands in Arctic Alaska over the period August 1998 to July 2019; this array is part of the Global Terrestrial Network for Permafrost (DOI/GTN-P). In addition to presenting data, this report also describes monitoring, data collection, and quality-control methods. The array of 16 monitoring stations spans lat 68.5°N. to 70.5°N. and long 142.5°W. to 161°W., an area of approximately 150,000 square kilometers. Climate summaries are presented along with quality-controlled data. Data collection is ongoing and includes the following climate- and permafrost-related variables: air temperature, wind speed and direction, ground temperature, soil moisture, snow depth, rainfall totals, up- and downwelling shortwave radiation, and atmospheric pressure. These data were collected by the U.S. Geological Survey in close collaboration with the Bureau of Land Management and the U.S. Fish and Wildlife Service.

Assessment of streamflow and water quality in the Upper Yampa River Basin, Colorado, 1992–2018

Released June 10, 2021 17:00 EST

2021, Scientific Investigations Report 2021-5016

Natalie K. Day

The Upper Yampa River Basin drains approximately 2,100 square miles west of the Continental Divide in north-western Colorado. There is a growing need to understand potential changes in the quantity and quality of water resources as the basin is undergoing increasing land and water development to support growing municipal, industrial, and recreational needs. The U.S. Geological Survey, in cooperation with stakeholders in the Upper Yampa River Basin water community, began a study to characterize and identify changes in streamflow and selected water-quality constituents, including  suspended sediment, Kjeldahl nitrogen, total nitrogen, total phosphorus, and orthophosphate, in the basin. This study used streamflow and water-quality data from selected U.S. Geological Survey sites to provide a better understanding of how major factors, including land use, climate change, and geological features, may influence streamflow and water quality.

Analysis of long-term (1910–2018) and short-term (1992–2018) records of streamflow at main-stem Yampa River and tributary sites indicate downward trends in one or more streamflow statistics, including 1-day maximum, mean, and 7-day minimum. Long-term downward trends in daily mean streamflow in April (22 percent overall) at Yampa River at Steamboat Springs, Colorado, correspond to observed changes in streamflow documented across western North America and the Colorado River Basin that are predominately associated with changes in snowmelt runoff and temperatures. During the short-term period of analysis, decreases in streamflow at main-stem Yampa River and some tributary sites are likely related to changes in consumptive use and reservoir management or, at sites with no upstream flow impoundments, changes in irrigation diversions and climate.

Concentrations of water-quality constituents were typically highest in spring (March, April, and May) during the early snowmelt runoff period as material that is washed off the land surface drains into streams. Highest concentrations occurred slightly later, in May, June, and July, at Yampa River above Stagecoach Reservoir, Colo., and slightly earlier, in February and March at Yampa River at Milner, Colo., indicating that these sites may have different or additional sources of phosphorus from upstream inputs. Yampa River at Milner, Colo., and Yampa River above Elkhead Creek, Colo., had the highest net yields of suspended sediment, Kjeldahl nitrogen, and total phosphorus, and are likely influenced by land use and erosion as the basins of both of these sites are underlain by highly erodible Cretaceous shales.

Upward trends in estimated Kjeldahl nitrogen and total phosphorus concentrations and loads were found at Yampa River at Steamboat Springs, Colo. From 1999 to 2018, the Kjeldahl nitrogen concentration increased by 10 percent or 0.035 milligram per liter, and load increased by 22 percent or 26 tons. Total phosphorus concentration increased by 20 percent or 0.0081 milligram per liter, and loads increased by 41 percent or 6.2 tons. Decreases in streamflow and changes in land use may contribute to these trends.

During multiple summer sampling events at Stagecoach Reservoir, the physical and chemical factors indicated conditions conducive to cyanobacterial blooms, including surface-water temperatures greater than 20 degrees Celsius and total phosphorus and total nitrogen concentrations in exceedance of Colorado Department of Public Health and Environment interim concentrations for water-quality standards. Local geological features (predominately sandstones and shales) and additional inputs from upstream land use likely contribute to the elevated nutrient conditions in Stagecoach Reservoir.

Estimating Piacenzian sea surface temperature using an alkenone-calibrated transfer function

Released June 10, 2021 13:12 EST

2021, Scientific Investigations Report 2021-5051

Harry J. Dowsett, Marci M. Robinson, Kevin M. Foley

Stationarity of environmental preferences is a primary assumption required for any paleoenvironmental reconstruction using fossil materials based upon calibration to modern organisms. Confidence in this assumption decreases the further back in time one goes, and the validity of the assumption that species temperature tolerances have not changed over time has been challenged in Pliocene studies. We use paired UK′37  (unsaturated ketones with 37 carbon atoms) sea surface temperature (SST) and faunal assemblage data to directly calibrate North Atlantic Piacenzian planktonic foraminifer assemblages to Piacenzian alkenone paleotemperature estimates to provide an alternative paleoceanographic reconstruction approach that does not rely on stationarity. In doing so, we extend Pliocene SST estimates to sites where only quantitative faunal assemblage data were previously available and improve the spatial resolution of the North Atlantic SST reconstruction.

Magnitude and frequency of floods in the alluvial plain of the lower Mississippi River, 2017

Released June 10, 2021 08:17 EST

2021, Scientific Investigations Report 2021-5046

Brandon T. Anderson

Annual exceedance probability flows at gaged locations and regional regression equations used to estimate annual exceedance probability flows at ungaged locations were developed by the U.S. Geological Survey, in cooperation with the Mississippi Department of Transportation, to improve flood-frequency estimates at rural streams in the alluvial plain of the lower Mississippi River. These estimates were developed using current geospatial data, analytical methods, and annual peak-flow data through September 2017 at 58 streamgages in the alluvial plain of the lower Mississippi River, including 9 in Mississippi, 35 in Arkansas, 4 in Missouri, and 10 in Louisiana. Annual exceedance probability flows presented in this report incorporate streamflow data through the 2017 water year, 32 additional years of record since the previous study in 1985 of flood magnitude and frequency in the Mississippi portion of the alluvial plain of the lower Mississippi River. Ranges for standard error of prediction, average variance of prediction, and pseudo-R2 are 45–61 percent, 0.035–0.059 (log cubic feet per second)2, and 90–94 percent, respectively.

Analysis of Escherichia coli, total recoverable iron, and dissolved selenium concentrations, loading, and identifying data gaps for selected 303(d) listed streams, Grand Valley, western Colorado, 1980–2018

Released June 09, 2021 14:00 EST

2021, Scientific Investigations Report 2021-5053

Lisa D. Miller, Rachel G. Gidley, Natalie K. Day, Judith C. Thomas

Tributaries to the Colorado River in the Grand Valley in western Colorado (segment COLCLC13b) have been placed on the State of Colorado 303(d) list as impaired for Escherichia coli (E. coli), total recoverable iron, and dissolved selenium. The Colorado Department of Public Health and Environment Water Quality Control Division is required to develop total maximum daily loads for these constituents in these tributaries. The U.S. Geological Survey, in cooperation with the Grand Valley Drainage District and Colorado Water Conservation Board, conducted a study to (1) characterize concentrations, loads, and load reductions for E. coli, total recoverable iron, and dissolved selenium using existing data and (2) identify water-quality data gaps to inform future monitoring strategies. This study analyzed water-quality and streamflow data for 3 main-stem sites (2 sites along the Colorado River and 1 site along the Gunnison River) and 29 selected sites on tributaries to the Colorado River.

Sample data were available at five sites along Adobe Creek and at six sites along Leach Creek, the two tributaries in the study area that are impaired for E. coli. All geometric mean E. coli concentrations at sites along Adobe Creek and Leach Creek exceeded the State recreational use standard of 126 colony forming units per 100 milliliters (CFU/100 mL). In Adobe Creek, E. coli concentrations in samples ranged from 45.7 to more than 2,420 CFU/100 mL (method upper reporting limit for undiluted samples), and geometric mean concentrations at sites ranged from 301 to 1,180 CFU/100 mL. The E. coli concentrations generally increased in the downstream direction in Adobe Creek; however, increases were not seen between all sites. The largest downstream increase in E. coli concentration was measured between the two most upstream sites. In Leach Creek, concentrations of E. coli in samples ranged from 25.9 to more than 2,420 CFU/100 mL, and geometric mean concentrations at sites ranged from 160 to 259 CFU/100 mL. The E. coli concentrations showed no consistent downgradient increase in Leach Creek. In fact, some of the highest E. coli concentrations were measured at the most upstream site, Leach Creek at Summer Hill Drive.

Total recoverable iron concentrations and loads were evaluated at 15 tributary sites for samples collected from August 1993 to February 2018. Median total recoverable iron concentrations ranged from 211 to 4,670 micrograms per liter (µg/L). The chronic aquatic-life water-quality standard (1,000 µg/L) was exceeded in most irrigation season (April through October) samples but was rarely exceeded in nonirrigation season (November through March) samples. Concentrations were often an order of magnitude higher in samples collected during irrigation season than in samples collected during nonirrigation season. None of the sites had enough concurrent total recoverable iron and streamflow data to compute annual loads. As with E. coli, the lack of concurrent total recoverable iron and streamflow information represents a data gap, which needs to be addressed to compute annual loads.

Dissolved selenium concentrations and loads were evaluated at 20 tributary sites using discrete water-quality data collected 1991–2018. Dissolved selenium concentrations were higher during nonirrigation season than during irrigation season at tributary sites. However, irrigation season dissolved selenium loads were generally higher than nonirrigation selenium loads, because streamflows were higher during irrigation season. Regression analysis was used to estimate daily dissolved selenium concentrations and loads at three main-stem sites for water years (WYs) 1980–2018 (Gunnison River near Grand Junction and Colorado River near Colorado-Utah State Line) and WYs 2002–18 (Colorado River near Cameo). A trend analysis of dissolved selenium concentrations and loads was completed for these sites from the same respective starting dates but ending in 2017. A continuing downward trend in dissolved selenium concentration was observed at all sites and across all seasonal designations of the analysis. The dissolved selenium concentration decreased by 0.12 µg/L from WY 2002 to 2017 at Colorado River near Cameo, representing an 18-percent decrease during the time period. The dissolved selenium concentration at Gunnison River near Grand Junction decreased by 4.2 µg/L from WY 1980 to 2017, representing a 56-percent decrease overall. During the same time period, dissolved selenium concentration at Colorado River near Colorado-Utah State Line decreased by 3.8 µg/L, representing a 56-percent decrease overall. A downward trend in dissolved selenium load was also observed at all sites and across all seasonal designations of the analysis. The relative contribution of dissolved selenium from the Grand Valley near Grand Junction was estimated by comparing loads at main-stem sites bracketing the study area. The two upstream sites, Colorado River near Cameo and Gunnison River near Grand Junction, contributed 60,300 cumulative pounds and 251,000 cumulative pounds, respectively, during WYs 2002–18. At the furthest downstream site, Colorado River near Colorado-Utah State Line, 490,000 cumulative pounds were estimated during the same time period, indicating that the region between Whitewater and State line contributed approximately 179,000 cumulative pounds or a mean annual load of 10,500 lb/yr. Grand Valley dissolved selenium contributions appear to be stable during WYs 2002–18.

Beyond streamflow: Call for a national data repository of streamflow presence for streams and rivers in the United States

Released June 09, 2021 07:10 EST

2021, Water (12)

Kristin Jaeger, Konrad Hafen, Jason B. Dunham, Ken M. Fritz, Stephanie K. Kampf, Theodore B. Barnhart, Kendra E. Kaiser, Roy Sando, Sherri L Johnson, Ryan R. McShane, Sarah Beth Dunn

Observations of the presence or absence of surface water in streams are useful for characterizing streamflow permanence, which includes the frequency, duration, and spatial extent of surface flow in streams and rivers. Such data are particularly valuable for headwater streams, which comprise the vast majority of channel length in stream networks, are often non-perennial, and are frequently the most data deficient. Datasets of surface water presence exist across multiple data collection groups in the United States but are not well aligned for easy integration. Given the value of these data, a unified approach for organizing information on surface water presence and absence collected by diverse surveys would facilitate more effective and broad application of these data and address the gap in streamflow data in headwaters. In this paper, we highlight the numerous existing datasets on surface water presence in headwater streams, including recently developed crowdsourcing approaches. We identify the challenges of integrating multiple surface water presence/absence datasets that include differences in the definitions and categories of streamflow status, data collection method, spatial and temporal resolution, and accuracy of geographic location. Finally, we provide a list of critical and useful components that could be used to integrate different streamflow permanence datasets.

Cape Romain partnership for coastal protection

Released June 08, 2021 16:20 EST

2021, Open-File Report 2021-1021

Mitchell J. Eaton, Fred A. Johnson, Jessica Mikels-Carrasco, David J. Case, Julien Martin, Bradley Stith, Simeon Yurek, Bradley Udell, Laura Villegas, Laura Taylor, Zulquarnain Haider, Hadi Charkhgard, Changhyun Kwon

This final report summarizes activities, outcomes, and lessons learned from a 3-year project titled “Climate Change Adaptation for Coastal National Wildlife Refuges” with the Cape Romain National Wildlife Refuge (NWR) and local partners in the surrounding South Carolina Lowcountry. The Lowcountry is classified as the 10-county area encompassing the coastal plain of South Carolina (this report specifically focuses on Berkeley, Charleston, and Georgetown Counties). The goals of this work, sponsored by the U.S. Geological Survey’s Southeast Climate Adaptation Science Center (SECASC), were to foster active engagement with stakeholders; to develop a comprehensive definition of adaptation problems faced by agencies, organizations, and individuals near the Cape Romain NWR that accounts for global change, local values, knowledge and perceptions; and to encourage social learning and building of effective networks and trust across South Carolina Lowcountry organizations and individuals. Although project scoping began at the scale of the Atlantic seaboard, by engaging with NWRs from Massachusetts to Florida, participating refuge personnel eventually selected the Cape Romain NWR to serve as a case study for testing our goals. The Cape Romain Partnership for Coastal Conservation was established to address global change impacts at a regional level and includes representation from Federal and State resource agencies, local conservation nongovernmental organizations, and organizations representing underserved community interests. Research topics, originating from discussions with Cape Romain Partnership for Coastal Conservation members, focused on quantifying key drivers of change including localized sea-level rise (SLR) predictions, estimates of coastal hurricane inundation as amplified by SLR, and urban growth trends and forecasts. These key drivers provided a foundation to engage stakeholders in planning exercises to begin a process of collective understanding and collaborative decision making. The goal of this process was to develop collective strategies of adaptation to enhance community and ecosystem resilience in the South Carolina Lowcountry.

South Carolina’s Lowcountry is experiencing rapid environmental and social transformation because of SLR rates approaching twice the global average, chronic tidal flooding and catastrophic storm surges, erosion and loss of habitats that provide essential services to wildlife and humans, and increasing social polarization fueled by aggressive low-density urban growth and other forms of land conversion. To support characterizations of plausible future scenarios, we used available or, in some cases, developed new models to project future conditions of key environmental and social-economic drivers. Because of the imprecision of mean global SLR projections, the SECASC commissioned a climatological study to account for local conditions and multiple representative concentration pathways to project a tailored distribution of future sea levels. These projections were matched to SLR scenarios provided by existing models to anticipate the range of future coastal habitat changes in the South Carolina Lowcountry. SLR scenarios were also incorporated into existing storm-surge models, which do not account for alternate baseline sea levels, to project the local effects of future hurricanes. To evaluate the extent and effects of population growth and urban expansion, we relied on an existing urban-growth model to map the spatial distribution of land-conversion probabilities, the total area of which is predicted to increase twofold to threefold over the next 60 years. In addition to this simplified model, an econometric model is in development to account for nonlinear feedback dynamics in land value, land use, and ecosystem service production. Although not yet completed, the goals of this model are to produce more-detailed projections of growth dynamics and to allow predictions of development patterns resulting from alternate land-use planning policies and incentives.

Collaborative planning for an uncertain future requires more than providing decision makers with information on future physical and ecological conditions; developing effective and consensual strategies must also integrate sociological values, multiple cultural perspectives, and an understanding of human behavior. To support broad stakeholder engagement in integrative approaches to adaptation planning, emphasis was placed on the importance of considering differences in how individuals perceive their environment and create meaning. Because cultural frameworks form the basis for perceptions and, ultimately, the behaviors of individuals and institutions, we describe a model of human behavior and how it can be used to understand the effect of cultural complexity and variation in perception on choices, behavioral change, and long-term maintenance of behaviors. We consider a model commonly used in the field of behavioral health that accommodates variation in human perception when describing stages of behavior and the dynamics of behavioral change. Tailoring communication and engagement activities to targeted stakeholders is likely to benefit from increased understanding of behavioral change processes.

The complex nature of this problem limited the usefulness of a traditional decision-analytic approach, we explored alternative methods for engagement, collaborative learning and decision making. Recognizing that project partners and Lowcountry stakeholders may be at different stages of preparedness and interest level for modifying behavior as a function of global change, we facilitated a scenario-planning exercise to familiarize partners with this well-established approach for communicating the opportunities and threats arising under alternative, plausible futures. We developed narratives for four alternative South Carolina Lowcountry scenarios to be used in later strategic planning that focus on quantitative trends for three primary drivers with high impact and high uncertainty: manifestations of climate change, social-political shifts at a global level, and forces of local value and power structures. This scenario-planning exercise underscored the complex relation between the temporospatial scale of the production of ecological goods and services and the institutional scale at which they are managed. We then guided the partners through an assessment of the relevant strengths and weaknesses of the Cape Romain Partnership for Coastal Protection, using the threats and opportunities characterized by each scenario to understand how the partnership might respond when attempting to meet conservation and societal objectives. The partnership identified key strengths including partnership experience, outreach and technical capacities, a substantial conservation land base, and high social cohesion in the South Carolina Lowcountry. Limited communication expertise, institutional inertia, and insufficient staffing and funding were recognized as important weaknesses across the partnership. By examining and scoring combinations of internal strengths and weaknesses and external threats and opportunities, the partnership developed sets of prioritized strategies to consider in the context of a given scenario. Although we had insufficient time to examine all scenarios in detail, the intent was to identify a portfolio of strategic actions to address threats and opportunities represented in multiple plausible futures. Top-ranking strategies encompassed a range of actions that focused on strengthening the conservation community and communicating the benefits of nature (that is, ecosystem services) to leveraging partnerships to expand land protection.

This report also details the methods and preliminary results of several models developed or applied in support of this project. Two parcel-selection algorithms were used to evaluate anticipated habitat changes and patterns of urban growth to guide decisions on optimal conservation reserve design to protect habitat communities. One approach used a widely available planning software (MARXAN) to maximize conservation benefits near the Cape Romain NWR, whereas the other approach was a novel application of economic theory to account for uncertainty in future conditions and for the risks of unanticipated habitat loss. This latter model applies modern portfolio theory to estimate the risk of investing in any portfolio of land parcels (that is, candidate “reserves”) under climate-change uncertainty by quantifying the variation and spatial correlation of conservation benefits derived from each portfolio. We expanded the range of actions beyond simply whether or not to invest in a set of land parcels, an approach commonly used in spatial conservation planning, to also include consideration of divestment from currently protected lands. Such refinements allow for better accounting of system dynamics and can evaluate the benefits of flexible conservation tools such as rolling easements. Model results were conditional on a decision maker’s risk tolerance but highlighted general strategies of land conservation to increase future habitat representation beyond what is expected under the current protected land base. We built models that may help inform coastal planning by estimating salinity dynamics and the performance of oyster reef restoration efforts to predict the combined effects of global change and management of freshwater flows on coastal habitats and the processes that contribute to their resilience. These models can support restoration decisions by evaluating the expected benefits of site locations for shoreline protection and fisheries production. Lastly, we developed a spatially explicit economic model that predicts feedback dynamics among land value, land-use change, and effects on ecosystem service provision to explore zoning policies and incentives on urban growth and ecosystem services.

We summarize these efforts with insights and considerations for the Cape Romain Partnership for Coastal Protection to continue to engage stakeholders in effective adaptation planning. First, notions of place attachment (referred to as sense of place), and the role of culture in social discourse are increasingly being used to understand the complex interactions between society and the environment and how societies respond and adapt to climate change. Sense of place was a unifying theme whenever the future of the South Carolina Lowcountry was discussed. The contribution of the South Carolina Lowcountry’s environmental wealth, rich cultural heritage, and quality of life to sense of place has important implications for how adaptation planning might best be pursued. More community-based governance of the commons (in other words, natural and cultural resources held in common), in which broad stakeholder participation and power sharing are key elements, is considered important. This devolution of governance is characterized by polycentric institutions and self-organizing social networks that promote a local culture of knowledge sharing, problem solving, and learning. These so-called bridging organizations (or individuals) often provide the leadership necessary to bring together potentially disparate Government agencies and institutions, private organizations, and individuals in a collective process of problem solving. Our observations also suggest that the conservation community in the South Carolina Lowcountry views its activities as integral to the broader governance of social-ecological systems, in which responses to the forces of global change are mediated through culture, economics, and politics. Rather than directly competing with other interests, the South Carolina Lowcountry conservation community seems to embrace an interpretation of conservation in which the fundamental objective is the quality of human life rather than environmental protection.

Fundamental to the types of governance reforms described above is the notion of coproduction, in which experts and users collaborate to develop a shared body of knowledge. In this approach, scientists work with stakeholders to help frame questions, design research, and collect and analyze data. Such sustained collaborations are increasingly believed to be an effective way to produce useable (or actionable) science. The emphasis on social learning, leveraging strong social networks, coordinating and deliberating among diverse stakeholders, and applying principles of adaptive management is an essential contribution to adaptive capacity. The diverse and robust set of scientific approaches, methods to help stakeholders collaborate in effective and goal-driven planning processes, and decision tools resulting from this project hopefully will assist Cape Romain NWR and its partners prepare for climatic, ecological, and social changes over the coming decades.

System characterization of Earth observation sensors

Released June 08, 2021 15:32 EST

2021, Open-File Report 2021-1030

This U.S. Geological Survey Open-File Report provides information from assessments of Earth observation sensors completed by the U.S. Geological Survey Earth Resources Observation and Science Cal/Val Center of Excellence. These reports are provided as independent measures of basic system performance by the Earth Resources Observation and Science Cal/Val Center of Excellence team by completing the geometric, radiometric, and spatial characterization. The results of these assessments are a snapshot in time.

Fluvial Egg Drift Simulator (FluEgg) user’s manual

Released June 08, 2021 11:02 EST

2021, Open-File Report 2021-1052

Marian M. Domanski, Jessica Z. LeRoy, Michael Berutti, P. Ryan Jackson

The Fluvial Egg Drift Simulator (FluEgg) was developed to simulate the transport and dispersion of invasive carp eggs and larvae in a river. FluEgg currently (2020) supports modeling of bighead carp (Hypophthalmichthys nobilis), silver carp (H. molitrix), and grass carp (Ctenopharyngodon idella), with the planned addition of black carp (Mylopharyngodon piceus) once developmental data are available. FluEgg integrates the biological development of invasive carp eggs and larvae with a particle transport model that simulates the advection and dispersion of the eggs and larvae based on user-supplied one-dimensional hydraulic conditions. FluEgg can be used to evaluate the hydrodynamic suitability of a river for invasive carp spawning, to inform sampling and monitoring efforts, and to identify the most likely spawning areas of captured eggs or larvae.

Developing a strategy for the national coordinated soil moisture monitoring network

Released June 08, 2021 07:46 EST

2021, Vadose Zone Journal

Micheal Cosh, Todd Caldwell, Bruce M. Baker, John D. Bolton, Nathan Edwards, Peter Goble, Heather Hofman, Tyson Ochsner, Steven Quiring, Charles W. Schalk, Marina Skumanich, Mark Svoboda, Molly Woloszyn

Soil moisture is a critical land surface variable, affecting a wide variety of climatological, agricultural, and hydrological processes. Determining the current soil moisture status is possible via a variety of methods, including in situ monitoring, remote sensing, and numerical modeling. Although all of these approaches are rapidly evolving, there is no cohesive strategy or framework to integrate these diverse information sources to develop and disseminate coordinated national soil moisture products that will improve our ability to understand climate variability. The National Coordinated Soil Moisture Monitoring Network initiative has developed a national strategy for network coordination with NOAA's National Integrated Drought Information System. The strategy is currently in review within NOAA, and work is underway to implement the initial milestones of the strategy. This update reviews the goals and steps being taken to establish this national-scale coordination for soil moisture monitoring in the United States.

Changes in the abundance and distribution of waterfowl wintering in the Central Valley of California, 1973–2000

Released June 08, 2021 07:35 EST

2021, Studies of Western Birds (3) 50-74

Joseph P. Fleskes, Michael L. Casazza, Cory T. Overton, Elliott L. Matchett, Julie L. Yee

The Central Valley of California is one of the most important areas for wintering waterfowl in the world and the focus of extensive conservation efforts to mitigate for historical losses and counter continuing stressors to habitats. To guide conservation, we analyzed trends in the abundance and distribution (spatiotemporal abundance patterns) of waterfowl and their habitats in the Central Valley and its major subregions (Sacramento Valley, Suisun Marsh, Delta, San Joaquin Valley), from 1973 through 2000. We used existing databases, satellite imagery, and aerial photography to measure habitat area, and aerial surveys and radio telemetry to track the abundance and distribution of wintering waterfowl. Wetlands increased throughout the Central Valley, but agricultural fields flooded after harvest increased greatly to the north in the Sacramento Valley and decreased to the south in the San Joaquin Valley, resulting in an overall increase in the relative availability of winter habitat in the former region. Reflecting the continental decline of the most abundant wintering species (Northern Pintail, Anas acuta), the overall abundance of wintering waterfowl in the Central Valley declined during our study. By contrast, numbers of the American Wigeon (A. americana), Mallard (A. platyrhynchos), and Northern Shoveler (A. clypeata) were stable, and numbers of the Green-winged Teal (A. crecca), Gadwall (A. strepera), diving ducks, and geese increased from 1973–1982 to 1998–2000. The areas of greatest abundance of wintering waterfowl within the Central Valley shifted northward as many species responded to changes in the distribution of habitats. Wintering waterfowl migrated earlier in fall and winter from the San Joaquin Valley, Suisun Marsh, and Delta to the Sacramento Valley, and fewer waterfowl emigrated from the Sacramento Valley to other parts of the Central Valley. Because changes in waterfowl distribution were primarily a response to the increase of a beneficial agricultural practice (i.e., the flooding of rice after harvest) in the Sacramento Valley, changing agro-economics, reduction of water supplies, or other factors that reduce this practice could change the abundance and distribution of wintering waterfowl in the Central Valley rapidly. Thus to maintain abundant suitable habitat and restore the historical distribution of wintering waterfowl, our results suggest a continuing need for the conservation of wetlands and other waterfowl habitats with secure water supplies throughout the Central Valley. Despite our findings, achieving goals for winter waterfowl populations in the Central Valley likely will depend on a combination of factors including some acting in breeding ranges farther north or elsewhere outside of the valley.

Nearshore fish species richness and species–habitat associations in the St. Clair–Detroit River System

Released June 08, 2021 06:55 EST

2021, Water (12)

Corbin D. Hilling, Jason L. Fischer, Jason E. Ross, Taaja Tucker, Robin L. DeBruyne, Christine M. Mayer, Edward F. Roseman

Shallow water riparian zones of large rivers provide important habitat for fishes, but anthropogenic influences have reduced the availability and quality of these habitats. In the St. Clair–Detroit River System, a Laurentian Great Lakes connecting channel, losses of riparian habitat contributed to impairment of fish populations and their habitats. We conducted a seine survey annually from 2013 to 2019 at ten sites in the St. Clair and Detroit rivers to assess riparian fish communities, and to identify habitat attributes associated with fish species richness and catches of common species. We captured a total of 38,451 fish representing 60 species, with emerald shiner Notropis atherinoides composing the largest portion of the catch. We used an information-theoretic approach to assess the associations between species richness and catches of 33 species with habitat variables (substrate, shoreline vegetation types, and aquatic macrophyte richness). Sand, cobble, and algal substrates and shoreline vegetation were important predictors of species richness based on a multimodel inference approach. However, habitat associations of individual species varied. This work identified manageable habitat variables associated with species richness, while identifying potential tradeoffs for individual species. Further, this work provides baselines for development and evaluation of fish community and shoreline habitat restoration goals.

Soil reservoir dynamics of ophidiomyces ophidiicola, the causative agent of snake fungal disease

Released June 08, 2021 06:52 EST

2021, Journal of Fungi (7)

Lewis J. Campbell, Joanna Burger, Robert T. Zappalorti, John F. Bunnell, Megan Winzeler, Daniel R. Taylor, Jeffrey M. Lorch

Wildlife diseases pose an ever-growing threat to global biodiversity. Understanding how wildlife pathogens are distributed in the environment and the ability of pathogens to form environmental reservoirs is critical to understanding and predicting disease dynamics within host populations. Snake fungal disease (SFD) is an emerging conservation threat to North American snake populations. The causative agent, Ophidiomyces ophidiicola (Oo), is detectable in environmentally derived soils. However, little is known about the distribution of Oo in the environment and the persistence and growth of Oo in soils. Here, we use quantitative PCR to detect Oo in soil samples collected from five snake dens. We compare the detection rates between soils collected from within underground snake hibernacula and associated, adjacent topsoil samples. Additionally, we used microcosm growth assays to assess the growth of Oo in soils and investigate whether the detection and growth of Oo are related to abiotic parameters and microbial communities of soil samples. We found that Oo is significantly more likely to be detected in hibernaculum soils compared to topsoils. We also found that Oo was capable of growth in sterile soil, but no growth occurred in soils with an active microbial community. A number of fungal genera were more abundant in soils that did not permit growth of Oo, versus those that did. Our results suggest that soils may display a high degree of both general and specific suppression of Oo in the environment. Harnessing environmental suppression presents opportunities to mitigate the impacts of SFD in wild snake populations.

System characterization report on the WorldView-3 Imager

Released June 07, 2021 09:23 EST

2021, Open-File Report 2021-1030-I

Simon J. Cantrell, Jon B. Christopherson, Cody Anderson, Gregory L. Stensaas, Shankar N. Ramaseri Chandra, Minsu Kim, Seonkyung Park

Executive Summary

This report addresses system characterization of the Maxar WorldView-3 satellite and is part of a series of system characterization reports produced and delivered by the U.S. Geological Survey Earth Resources Observation and Science Cal/Val Center of Excellence in 2020. These reports present and detail the methodology and procedures for characterization; present technical and operational information about the specific sensing system being evaluated; and provide a summary of test measurements, data retention practices, data analysis results, and conclusions.

WorldView-3 is a high-resolution multispectral satellite launched in 2014 by Maxar Technologies on an Atlas V launch vehicle from Vandenberg Air Force Base in California for Earth resources monitoring. WorldView-3 provides substantial technical improvements to previous WorldView satellites, including spectral bands, ground sample distance, and swath. The WorldView-3 satellite was designed and built by Lockheed Martin for Maxar Technologies using the BCP–5000 bus with the WorldView-3 Imager and the Clouds, Aerosols, Vapors, Ice, and Snow sensor. The high-resolution WorldView-3 Imager is the main instrument, and the Clouds, Aerosols, Vapors, Ice, and Snow sensor provides additional data on obscurants and other atmospheric effects used in data production. More information on Maxar WorldView satellites and sensors is available within the “2020 Joint Agency Commercial Imagery Evaluation—Remote Sensing Satellite Compendium” and from the manufacturer at https://www.maxar.com/.

The Earth Resources Observation and Science Cal/Val Center of Excellence system characterization team completed data analyses to characterize the geometric (interior and exterior), radiometric, and spatial performances. Results of these analyses indicate that WorldView-3 has a range of interior geometric performance of −0.09 (−0.07 pixel) to 0.24 meter (0.19 pixel) in band-to-band registration; an exterior geometric performance in the range of a −21.10- (−2.11 pixels) to 28.23-meter (2.82 pixels) offset in comparison to Sentinel-2; a radiometric performance in the range of 0.007 to 0.874 (offset and slope); and a spatial performance in the range of 1.2 to 1.7 pixels at full width at half maximum with a modulation transfer function at a Nyquist frequency in the range of 0.093 to 0.185.

System characterization report on the Gaofen-1

Released June 07, 2021 09:22 EST

2021, Open-File Report 2021-1030-B

Mahesh Shrestha, Aparajithan Sampath, Shankar N. Ramaseri Chandra, Jon B. Christopherson, Jerad Shaw, Gregory L. Stensaas, Cody Anderson

Executive Summary

This report addresses system characterization of Gaofen-1 and is part of a series of system characterization reports produced and delivered by the U.S. Geological Survey Earth Resources Observation and Science Cal/Val Center of Excellence in 2020. These reports present the detail methodology and procedures for characterization; present technical and operational information about the specific sensing system being evaluated; and provide a summary of test measurements, data retention practices, data analysis results, and conclusions.

Gaofen represents a series of Chinese high-resolution Earth observation satellites. More than 12 satellites have been launched in the Gaofen series, beginning with Gaofen-1 in 2013. Satellites within the series have varying infrared, radar, and optical imaging capabilities. The primary goal for the satellite is to provide near real-time observations for climate change monitoring, geographical mapping, precision agriculture support, environmental and resource surveying, and disaster prevention. More information on Chinese satellites and sensors is available within the “2020 Joint Agency Commercial Imagery Evaluation—Remote Sensing Satellite Compendium” and at http://www.cnsageo.com/#/detailIndex?secondIndex=2&id=3&code=8.

The Earth Resources Observation and Science Cal/Val Center of Excellence System Characterization team completed data analyses to characterize the geometric (interior and exterior), radiometric, and spatial performances. Results of these analyses indicate that Gaofen-1 has an interior geometric performance of −0.48 meter (m) (−0.03 pixel) northing and 0.42 m (0.03 pixel) easting offset for band 1, −0.99 m (−0.06 pixel) northing and −0.38 m (−0.02 pixel) easting offset for band 2, −0.45 m (−0.03) northing and 0.83 m (0.05 pixel) easting offset for band 3, −3.20 m (−0.20 pixel) northing and 1.44 m (0.09 pixel) easting offset for band 4 in band-to-band registration. Similarly, Gaofen-1 has an exterior geometric performance of 7.50 m (0.48 pixel) easting and 109.50 m (7.30 pixels) northing offset in comparison to the Landsat 8 Operational Land Imager; a radiometric performance in the range of −0.014 to 0.149 (absolute reflective difference); and a spatial performance in the range of 1.1 to 2.0 pixels at full width at half maximum, with a modulation transfer function at a Nyquist frequency in the range of 0.040 to 0.250.

System characterization report on the German Aerospace Center (DLR) Earth Sensing Imaging Spectrometer (DESIS)

Released June 07, 2021 09:22 EST

2021, Open-File Report 2021-1030-A

Mahesh Shrestha, Aparajithan Sampath, Shankar N. Ramaseri Chandra, Jon B. Christopherson, Jerad Shaw, Cody Anderson

Executive Summary

This report addresses system characterization of the German Aerospace Center (DLR) Earth Sensing Imaging Spectrometer (DESIS) and is part of a series of system characterization reports produced and delivered by the U.S. Geological Survey Earth Resources Observation and Science Cal/Val Center of Excellence. These reports present the methodology and procedures for characterization and the technical and operational information about the specific sensing system being evaluated. These reports also provide a description of data measurements, data retention practices, and data analysis results and provide system characterization conclusions.

In partnership with Teledyne Brown Engineering, DLR built the DESIS hyperspectral instrument, which Teledyne Brown Engineering then integrated onto its International Space Station-based imaging platform, the Multi-User System for Earth Sensing. DLR developed the processing software and, together with Innovative Imaging and Research, completes the validation and calibration of the data products. DESIS was launched in 2018, and the data are used for scientific research in atmospheric physics and Earth sciences. The DESIS sensor contributes to the scientific and commercial utilization of the International Space Station and helps to further hyperspectral remote sensing technologies for future satellites. More information on DLR satellites and sensors is included within the “2020 Joint Agency Commercial Imagery Evaluation—Remote Sensing Satellite Compendium” and at https://www.dlr.de/DE/Home/home_node.html.

The Earth Resources Observation and Science Cal/Val Center of Excellence system characterization team completed data analyses to characterize the geometric (interior and exterior), radiometric, and spatial performances. Results of these analyses indicate that DESIS has an interior geometric performance of less than a 3.30-meter (less than 0.11 pixel) root mean square error in band-to-band registration, an exterior geometric performance in the range of a 2.40- (0.08 pixel) to 17.40-meter (0.58 pixel) offset in comparison to the Landsat 8 Operational Land Imager, a radiometric performance in the range of −0.013 to 1.011 (offset and slope), and a spatial performance for band 130 of 1.5 pixels at full width at half maximum, with a modulation transfer function at a Nyquist frequency of 0.167.

Direct and size-mediated effects of temperature and ration-dependent growth rates on energy reserves in juvenile anadromous alewives (Alosa pseudoharengus)

Released June 07, 2021 07:27 EST

2021, Journal of Fish Biology

Liang Guo, Stephen D. McCormick, Eric T. Schultz, Adrian Jordaan

Growth rate and energy reserves are important determinants of fitness and are governed by endogenous and exogenous factors. Thus, examining the influence of individual and multiple stressors on growth and energy reserves can help estimate population health under current and future conditions. In young anadromous fishes, freshwater habitat quality determines physiological state and fitness of juveniles emigrating to marine habitats. We tested how temperature and food availability affect survival, growth, and energy reserves in juvenile anadromous alewives (Alosa pseudoharengus), a forage fish distributed along the eastern North American continent. Field-collected juvenile anadromous A. pseudoharengus were exposed for 21 days to one of two temperatures (21°C and 25°C) and one of two levels of food rations (1% or 2% tank biomass daily) and compared for differences in final size, fat mass-at-length, lean mass-at-length, and energy density. Increased temperature and reduced ration both led to lower growth rates and the effect of reduced ration was greater at higher temperature. Fat mass-at-length decreased with dry mass and energy density increased with total length, suggesting size-based endogenous influences on energy reserves. Lower ration also directly decreased fat mass-at-length, lean mass-at-length and energy density. Given the fitness implications of size and energy reserves, temperature and food availability should be considered important indicators of nursery habitat quality and incorporated in A. pseudoharengus life history models to improve forecasting of population health under climate change.

Untargeted lipidomics for determining cellular and sub-cellular responses in Zebrafish (Danio rerio) liver cells following exposure to complex mixtures in U.S. streams

Released June 07, 2021 07:02 EST

2021, Environmental Science & Technology

Huajun Zhen, Quincy Teng, Jonathan D Mosley, Timothy W. Collette, Yang Yue, Paul Bradley, Drew R. Ekman

Surface waters often contain a variety of chemical contaminants potentially capable of producing adverse outcomes in both humans and wildlife due to impacts from industrial, urban, and agricultural activity. Here, we report the results of a zebrafish liver (ZFL) cell-based lipidomics approach to assess the potential ecotoxicological effects of complex contaminant mixtures using water collected from eight impacted streams across the United States mainland and Puerto Rico. We initially characterized the ZFL lipidome using high resolution mass spectrometry, resulting in the annotation of 508 lipid species covering 27 classes. We then identified lipid changes induced by all streamwater samples (nonspecific stress indicators) as well as those unique to water samples taken from specific streams. Subcellular impacts were classified based on organelle-specific lipid changes, including increased lipid saturation (endoplasmic reticulum stress), elevated bis(monoacylglycero)phosphate (lysosomal overload), decreased ubiquinone (mitochondrial dysfunction), and elevated ether lipids (peroxisomal stress). Finally, we demonstrate how these results can uniquely inform environmental monitoring and risk assessments of surface waters.

Deposit classification scheme for the Critical Minerals Mapping Initiative Global Geochemical Database

Released June 04, 2021 16:00 EST

2021, Open-File Report 2021-1049

Albert H. Hofstra, Vladimir Lisitsin, Louise Corriveau, Suzanne Paradis, Jan Peter, Kathleen Lauzière, Christopher Lawley, Michael Gadd, Jean-Luc Pilote, Ian Honsberger, Evgeniy Bastrakov, David Champion, Karol Czarnota, Michael Doublier, David Huston, Oliver Raymond, Simon VanDerWielen, Poul Emsbo, Matthew Granitto, Douglas Kreiner

A challenge for the global economy is to meet the growing demand for commodities used in today’s advanced technologies. Critical minerals are commodities (for example, elements, compounds, minerals) deemed vital to the economic and national security of individual countries that are vulnerable to supply disruption. The national geological agencies of Australia, Canada, and the United States recently joined forces to advance understanding and foster development of critical mineral resources in their respective countries through the Critical Minerals Mapping Initiative (CMMI). An initial goal of the CMMI is to fill the knowledge gap on the abundance of critical minerals in ores. To do this, the CMMI compiled modern multielement geochemical data generated by each agency on ore samples collected from historical and active mines and prospects from around the world. To identify relationships between critical minerals, deposit types, deposit environments, and mineral systems, a unified deposit classification scheme was needed. This report describes the scheme developed by the CMMI to classify the initial release of geochemical data. In 2021, the resulting database—along with basic query, statistical analysis, and display tools—will be served to the public through a web-based portal managed by Geoscience Australia. The database will enable users to trace critical minerals through mineral systems and identify individual deposits or deposit types that are potential sources of critical minerals.

Remote and local drivers of Pleistocene South Asian summer monsoon precipitation: A test for future predictions

Released June 04, 2021 07:42 EST

2021, Science Advances (7)

Steven C Clemens, Masanobu Yamamoto, Kaustubh Thirumalai, Liviu Giosan, Julie N. Richey, Katrina Nilson-Kerr, Yair Rosenthal, Pallavi Anand, Sarah M McGrath

South Asian precipitation amount and extreme variability are predicted to increase due to thermodynamic effects of increased 21st-century greenhouse gases, accompanied by an increased supply of moisture from the southern hemisphere Indian Ocean. We reconstructed South Asian summer monsoon precipitation and runoff into the Bay of Bengal to assess the extent to which these factors also operated in the Pleistocene, a time of large-scale natural changes in carbon dioxide and ice volume. South Asian precipitation and runoff are strongly coherent with, and lag, atmospheric carbon dioxide changes at Earth’s orbital eccentricity, obliquity, and precession bands and are closely tied to cross-equatorial wind strength at the precession band. We find that the projected monsoon response to ongoing, rapid high-latitude ice melt and rising carbon dioxide levels is fully consistent with dynamics of the past 0.9 million years.

Oxygen-controlled recirculating seepage meter reveals extent of nitrogen transformation in discharging coastal groundwater at the aquifer–estuary interface

Released June 04, 2021 07:30 EST

2021, Limnology and Oceanography

Thomas W. Brooks, Kevin D. Kroeger, Holly A. Michael, Joanna K. York

Nutrient loads delivered to estuaries via submarine groundwater discharge (SGD) play an important role in the nitrogen (N) budget and eutrophication status. However, accurate and reliable quantification of the chemical flux across the final decimeters and centimeters at the sediment–estuary interface remains a challenge, because there is significant potential for biogeochemical alteration due to contrasting conditions in the coastal aquifer and surface sediment. Here, a novel, oxygen- and light-regulated ultrasonic seepage meter, and a standard seepage meter, were used to measure SGD and calculate N species fluxes across the sediment–estuary interface. Coupling the measurements to an endmember approach based on subsurface N concentrations and an assumption of conservative transport enabled estimation of the extent of transformation occurring in discharging groundwater within the benthic zone. Biogeochemical transformation within reactive estuarine surface sediment was a dominant driver in modifying the N flux carried upward by SGD, and resulted in a similar percentage of N removal (~ 42–52%) as did transformations occurring deeper within the coastal aquifer salinity mixing zone (~ 42–47%). Seasonal shifts in the relative importance of biogeochemical processes including denitrification, nitrification, dissimilatory nitrate reduction, and assimilation altered the composition of the flux to estuarine surface water, which was dominated by ammonium in June and by nitrate in August, despite the endmember-based observation that fixed N in discharging groundwater was strongly dominated by nitrate. This may have important ramifications for the ecology and management of estuaries, since past N loading estimates have generally assumed conservative transport from the nearshore aquifer to estuary.

11-Deoxycortisol is a stress responsive and gluconeogenic hormone in the jawless vertebrate, the sea lamprey (Petromyzon marinus)

Released June 04, 2021 07:22 EST

2021, Journal of Experimental Biology (224)

Ciaran A. Shaughnessy, Stephen D. McCormick

Although corticosteroid-mediated hepatic gluconeogenic activity in response to stress has been extensively studied in fishes and other vertebrates, there is little information on the stress response in basal vertebrates. In sea lamprey (Petromyzon marinus), a representative member of the most basal extant vertebrate group Agnatha, 11-deoxycortisol and deoxycorticosterone are the major circulating corticosteroids. The present study examined changes in circulating glucose and 11-deoxycortisol concentrations in response to a physical stressor. Furthermore, the gluconeogenic actions of 11-deoxycortisol and deoxycorticosterone were examined. Within 6 h of exposure of larval and juvenile sea lamprey to an acute handling stress, plasma 11-deoxycortisol levels increased 15- and 6-fold, respectively, and plasma glucose increased 3- and 4-fold, respectively. Radiometric receptor binding studies revealed that a corticosteroid receptor (CR) is present in the liver at lower abundance than in other tissues (gill and anterior intestine) and that the binding affinity of the liver CR was similar for 11-deoxycortisol and deoxycorticosterone. Transcriptional tissue profiles indicate a wide distribution of cr transcription, kidney-specific transcription of steroidogenic acute regulatory protein (star) and liver-specific transcription of phosphoenolpyruvate carboxykinase (pepck). Ex vivo incubation of liver tissue with 11-deoxycortisol resulted in dose-dependent increases in pepck mRNA levels. Finally, intraperitoneal administration of 11-deoxycortisol and deoxycorticosterone demonstrated that only 11-deoxycortisol resulted in an increase in plasma glucose. Together, these results provide the first direct evidence for the gluconeogenic activity of 11-deoxycortisol in an agnathan, indicating that corticosteroid regulation of plasma glucose is a basal trait among vertebrates.

Water resources of St. Landry Parish, Louisiana

Released June 03, 2021 11:08 EST

2021, Fact Sheet 2021-3026

Maxwell A. Lindaman, Vincent E. White

Information concerning the availability, use, and quality of water in St. Landry Parish, Louisiana, is critical for proper water-supply management. The purpose of this fact sheet is to present information that can be used by water managers, parish residents, and others for stewardship of this vital resource. In 2014, about 116.75 million gallons per day (Mgal/d) of water were withdrawn in St. Landry Parish: about 98.13 Mgal/d from groundwater sources and 18.62 Mgal/d from surface-water sources. Withdrawals for agricultural use, composed of general irrigation, rice irrigation, aquaculture, and livestock uses, accounted for about 90 percent (105.31 Mgal/d) of the total water withdrawn. Other categories of use included public supply, which accounted for about 8 percent of the total water withdrawn (9.77 Mgal/d), industry which accounted for about 1 percent (1.03 Mgal/d), and rural domestic which accounted for about 1 percent (0.65 Mgal/d). Water-use data collected at 5-year intervals from 1960 to 2010 and again in 2014 indicated that water withdrawals peaked in 1965 at 194.57 Mgal/d due to a large reported surface-water withdrawal of 144.00 Mgal/d for power generation that was not reported for other years.

Workflow for using unmanned aircraft systems and traditional geospatial data to delineate agricultural drainage tiles at edge-of-field sites

Released June 03, 2021 10:27 EST

2021, Scientific Investigations Report 2021-5013

J. Jeremy Webber, Tanja N. Williamson

Managing nutrient and sediment runoff from fields that drain to the Great Lakes is key to mitigating harmful algal blooms. Implementation of best management practices on agricultural land is considered a critical step to improving water quality in these streams, however the effect of these best management practices is difficult to quantify. The purpose of this study was to use a suite of high-resolution imagery acquired with unmanned aircraft systems (including a combination of visible, multispectral, and thermal cameras) to better characterize edge-of-field (EOF) sites in Michigan and Wisconsin that are monitored in cooperation with the Great Lakes Restoration Initiative. This high-resolution imagery (2.5–12-centimeter ground resolution) was used to delineate artificial subsurface drainage (tile-drain) networks and surface water flow paths that indicate contributing areas (that is, all area that drains to a monitored point) at these EOF sites, providing better characterization of each study site. Contributing areas for these sites ranged from 2.86 to 5.07 hectares and, among the sites, tile drains were identified as those that followed soil properties and those that were more densely patterned networks. These surveys also indicated that the contributing area monitored at the EOF sites may cross field boundaries and is not always coincident with the area underlain by subsurface drainage.

Short communication: evidence for geologic control of rip channels along Prince Edward Island, Canada

Released June 03, 2021 07:44 EST

2021, Physical Geography

Phillipe Alan Wernette, Chris Houser

Rip currents can move unsuspecting swimmers offshore rapidly and represent a significant risk to beach users worldwide, including along the northern coast of Prince Edward Island (PEI), Canada. Although many rip currents are ephemeral and/or spatially variable in response to changes in the nearshore bar morphology and wave and tidal forcing, it is possible for rip channels to be geologically controlled and quasi-permanent in morphology, location, and flow. Several rip channels along the northern coast of PEI appear in the same location from year to year and correspond to elongated lakes, rivers, or swales behind the modern coastal dune system. Given their persistent location and alignment with back dune hydrology, ground-penetrating radar surveys were collected along Brackley and Cavendish Beaches in July 2019 to determine whether persistent rip channels are associated with now-buried river channels extending beneath the modern dunes and continuing offshore. Strong reflectors similar to V-shaped river valleys are present in alongshore transects at both beaches. These infilled valleys align with back-dune hydrology and persistent rip channels, suggesting modern rip channels are structurally controlled and maintained by antecedent geology. This link provides important guidance to beach access management and the distribution of lifesaving strategies along the affected beaches.

Wildfires and global change

Released June 03, 2021 07:35 EST

2021, Frontiers in Ecology and the Environment

Juli G. Pausas, Jon Keeley

No single factor produces wildfires; rather, they occur when fire thresholds (ignitions, fuels, and drought) are crossed. Anomalous weather events may lower these thresholds and thereby enhance the likelihood and spread of wildfires. Climate change increases the frequency with which some of these thresholds are crossed, extending the duration of the fire season and increasing the frequency of dry years. However, climate-related factors do not explain all of the complexity of global fire-regime changes, as altered ignition patterns (eg human behavior) and fuel structures (eg land-use changes, fire suppression, drought-induced dieback, fragmentation) are extremely important. When the thresholds are crossed, the size of a fire will largely depend on the duration of the fire weather and the extent of the available area with continuous fuels in the landscape.

Tracking the source of metals to the San Juan River

Released June 03, 2021 06:22 EST

2021, Fact Sheet 2021-3029

Johanna M. Blake, Shaleene B. Chavarria, Anne-Marie Matherne

Introduction

The San Juan River is a major water source for communities in the Four Corners Region of the United States (Colorado, Arizona, New Mexico, Utah) and is a vital source of water for the Navajo Nation. The Navajo Nation Environmental Protection Agency (NNEPA) periodically samples surface water on the Navajo Nation and has found that some elements exceed NNEPA surface water standards (the upper limits of an element for consumption or other use of water). Constituents of concern are substances that could be harmful if present in sufficient quantities, and it is important to keep track of the concentrations of these substances in the environment. In the San Juan River, constituents of concern include metals detected in river water, such as arsenic, lead, and aluminum. These metals can come from natural sources or can result from human activities (anthropogenic) and can affect the health of people, plants, and animals. The Animas River is one natural source of metals to the San Juan River because of the types of rock through which the Animas River flows and because of hard rock mining at the headwaters. Other potential sources of metals are oil and gas development, coal mining, coal-fired power plants, urban areas, illegal trash dumping, abandoned uranium mines and mills, overgrazed areas, natural geology, and leaching from subsurface agricultural return flows. Determining how much each of these sources contributes and the relative effect of each source on San Juan River water will help the Navajo Nation in their efforts to protect human health and the environment along the San Juan River.

The U.S. Geological Survey (USGS) is working with the NNEPA to identify sources of metals and trace elements entering the San Juan River from tributaries in the reach flowing through the Navajo Nation and to quantify the contribution from each natural and human-caused source. The USGS and NNEPA are working with local community members to locate tributaries where sampling equipment can be installed. The 3-year source-tracking project, starting in spring 2021, will identify where metals at concentrations above safe surface water standards might be entering the river by evaluating the chemical signatures of water in the major tributaries of the San Juan River. Results will provide valuable information to the Navajo Nation, public drinking-water managers, irrigation districts, other stakeholders, scientists, and the public.

Impacts of sediment removal from and placement in coastal barrier island systems

Released June 02, 2021 09:00 EST

2021, Open-File Report 2021-1062

Jennifer L. Miselis, James G. Flocks, Sara Zeigler, Davina Passeri, David R. Smith, Jill Bourque, Christopher R. Sherwood, Christopher G. Smith, Daniel J. Ciarletta, Kathryn Smith, Kristen Hart, David Kazyak, Alicia Berlin, Bianca Prohaska, Teresa Calleson, Kristi Yanchis

Executive Summary

On June 24, 2019, Congressman Raul Grijalva of Arizona, Chair of the House Committee on Natural Resources, sent a letter to the directors of the U.S. Fish and Wildlife Service and the U.S. Geological Survey to request their assistance in answering questions regarding coastal sediment resource management within the Coastal Barrier Resources System as defined by the Coastal Barrier Resources Act (Public Law 97–348; 96 Stat. 1653; 16 U.S.C. 3501 et seq.). For the purposes of this response, coastal sediment resource management refers to the removal of sediment from one part of a barrier island system for placement in another part of the coastal system, for either hazard mitigation (for example, erosion or flood control) or coastal restoration (for example, expansion or restoration of beach, dune, and [or] marsh habitats). The specific topics of concern are as follows (paraphrased from Congressman Grijalva’s letter):

1. Disruption of coastal sediment supply resulting from sediment removal and placement, including the replenishment rate of removed sediments and impacts to other components of the barrier island system (discussed in sec. 3).

2. Physical and biological impacts of sediment removal and placement on benthic habitats (discussed in sec. 4).

3. Impacts of sediment removal and placement on fish and other marine species (discussed in sec. 5).

4. Changes in migratory bird nesting and foraging habitats resulting from sediment removal and placement (discussed in sec. 6).

5. Long-term impacts of sediment removal and placement on physical coastal resiliency (discussed in sec. 7).

Use of dissolved oxygen monitoring to evaluate phosphorus loading in Connecticut streams, 2015–18

Released June 02, 2021 08:11 EST

2021, Scientific Investigations Report 2021-5024

Brittney Izbicki, Jonathan Morrison

The Connecticut Department of Energy and Environmental Protection (CT DEEP) has developed an interim phosphorus reduction strategy to establish water-quality-based phosphorus limits in nontidal freshwaters for industrial and municipal water pollution control facilities. A recommendation in the strategy included the addition of diurnal dissolved oxygen (DO) sampling to the sampling of diatom communities collected by CT DEEP. The chemistry data coupled with biological data will help to examine the effects of phosphorus loading in streams. The U.S. Geological Survey (USGS), in cooperation with the CT DEEP and New England Interstate Water Pollution Control Commission, implemented a summer DO monitoring program from 2015 to 2018 to examine the effects of phosphorus loading in streams. Continuous DO data were collected at 18 sites in streams with varying concentrations of phosphorus throughout the State of Connecticut. Discrete water-quality nutrient data were collected by the USGS at 11 of the 18 sites. All continuous and discrete data collected from June to September for the 4 years were examined for all sites. This report documents a pattern of diurnal DO for monitoring sites across 4 years and presents estimated daily gross primary productivity (GPP), ecosystem respiration (ER), and a standardized rate coefficient for gas exchange for selected streams. Relations of phosphorus concentrations to the diurnal DO response and stream metabolism are described. Interannual variability in average annual total phosphorus (TP) concentrations and maximum daily DO concentrations were evaluated among sites in years of the study. Streams identified as impaired by CT DEEP such as Naugatuck River at Beacon Falls (USGS station 01208500), Still River at Route 7 at Brookfield Center (USGS station 01201487), and Quinnipiac River at Wallingford (USGS station 01196500) had higher TP concentrations (greater than 0.10 milligram per liter [mg/L]) throughout the study. Reference streams considered unimpaired had lower concentrations of TP (less than 0.10 mg/L). The range in daily DO concentrations remained less than 4 mg/L for most of the sites during the study except for Naugatuck River at Beacon Falls and Still River at Route 7 at Brookfield Center. Daily GPP and ER were summarized for 11 sites using the maximum likelihood estimation model of the streamMetabolizer package in the R statistical program. The models indicated that most sites had an estimated negative net primary productivity, based on the daily estimates of GPP and ER, which indicates the systems are heterotrophic and dominated by respiration. The high variation of GPP and ER reported for several sites can be affected by many physical, chemical, and biological factors, including the abundance and community composition of phytoplankton, periphyton, and macrophyte algae present. The variability in mean GPP was similar to the variability in maximum DO concentrations when plotted against annual average TP concentrations for the maximum likelihood estimation model in streamMetabolizer. The concept that phosphorus loading can affect the stream metabolism requires more detailed knowledge of stream geomorphic variables (canopy cover, stream velocity, water depth) and algal communities to help improve the scientific basis for managing phosphorus loading.

Short‐period surface‐wave tomography in the continental United States—A resource for research

Released June 02, 2021 07:32 EST

2021, Seismological Research Letters

R. B. Herrmann, C. J. Ammon, Harley M. Benz, A. Aziz-Zanjani, J. Boschelli

 grid for the four independent tomographic inversions (Love and Rayleigh and phase and group velocity). One reason for trying to obtain short‐period dispersion was to have a data set capable of constraining upper crust velocity models for use in determining regional moment tensors. The benefit of focusing on short‐period dispersion is apparent in the tomography maps—shallow geologic structures such as the Mid‐Continent Rift, and the Michigan, Illinois, Anadarko, Arkoma, and Appalachian basins are imaged. In our processing, we noted that the phase velocities were more robustly determined than the group velocities. We also noted that the inability to obtain dispersion at short periods shows distinct regional patterns that may be related to the local upper crust structure.

Sediment concentrations and loads upstream from and through John Redmond Reservoir, east-central Kansas, 2010–19

Released June 02, 2021 06:12 EST

2021, Scientific Investigations Report 2021-5037

Ariele R. Kramer, Cara L. Peterman-Phipps, Matthew D. Mahoney, Bradley S. Lukasz

Streambank erosion and reservoir sedimentation are primary concerns of resource managers in Kansas and throughout many regions of the United States and negatively affect flood control, water supply, and recreation. The Cottonwood and upper Neosho Rivers drain into John Redmond Reservoir, and since reservoir completion in 1964, there has been substantial conservation-pool sedimentation and storage loss in John Redmond Reservoir, causing storage capacity losses more rapidly than most other Federal reservoirs in Kansas. The U.S. Geological Survey (USGS), in cooperation with the Kansas Water Office, has monitored water quality (temperature, specific conductance, and turbidity) on the Cottonwood River (upstream from the reservoir) and Neosho River (upstream and downstream from the reservoir) since 2007 with additional sites added in 2009. The purpose of this report is to quantify suspended-sediment concentrations, loads, and yields entering and exiting John Redmond Reservoir during January 1, 2010, through December 31, 2019.

Three water-quality monitoring sites were upstream from the reservoir (Cottonwood River near Plymouth, Kansas [USGS site 07182250; hereinafter referred to as “Cottonwood”]; Neosho River at Burlingame Road near Emporia, Kans. [USGS site 07179750; hereinafter referred to as “Burlingame”]; and Neosho River at Neosho Rapids, Kans. [USGS site 07182390; hereinafter referred to as “Neosho Rapids”]), and one water-quality monitoring site was downstream from the reservoir (Neosho River at Burlington, Kans. [USGS site 07182510; hereinafter referred to as “Burlington”]). The Neosho Rapids streamgage is downstream from the confluence of the Cottonwood and upper Neosho Rivers and has a contributing drainage area accounting for 91 percent of the total contributing drainage area to John Redmond Reservoir.

Continuously measured streamflow, water quality, and discrete water-quality data were used to develop updated regression models to compute suspended-sediment concentrations, loads, and yields upstream and downstream from John Redmond Reservoir in east-central Kansas. Several turbidity sensors were deployed during the analysis period, and there are no established relations between the sensors; therefore, individual models for each sensor were developed. Model statistics for the turbidity and suspended-sediment concentration linear regression models were better (based on the coefficient of determination, root mean square error, and model standard percentage error) than the streamflow and suspended-sediment concentration linear regression models, indicating better model performance. Computed concentrations, loads, and yields do not account for the ungaged 9 percent of the drainage basin downstream from the Neosho Rapids streamgage.

Mean daily suspended-sediment loads upstream from the reservoir were largest at Neosho Rapids (2,250 tons), second largest at Cottonwood (2,180 tons), and smallest at Burlingame (624 tons). Streamflow at Burlington was predominately regulated by reservoir releases, and mean daily suspended-sediment loads were smaller (286 tons) than at upstream sites. Among the upstream sites, Cottonwood had the largest mean daily suspended-sediment concentration (179 milligrams per liter [mg/L]), followed by Neosho Rapids (162 mg/L), and Burlingame (108 mg/L). Burlington had the smallest mean daily suspended-sediment concentration of all sites (46 mg/L).

Annual reservoir trapping efficiency ranged from 82 to 94 percent, and the largest sediment mass trapped was during 2019 (2,230,000 tons). Reservoir storage decreased an estimated 7,750 acre-feet during 2010 and 2014–19. Using the mean trapping efficiency to estimate suspended-sediment loads during years with missing data (2011–13), the total estimated reservoir storage lost to sedimentation for the analysis period (2010–19) was 8,690 acre-feet, about 17 percent of the remaining storage space reported in 2007. The mean annual sedimentation rate during the analysis period (747 acre-feet per year) was about 85 percent larger than the design sedimentation rate (404 acre-feet per year) originally projected during construction. Different reservoir outflow management strategies, including operating near normal capacity as opposed to higher flood pool levels, could reduce the total reservoir storage lost by 3 percent (about 261 acre-feet), which is equal to 14 percent of the total sediment removed during the dredging operation in 2016.

During the study period, about 56 percent of the total suspended-sediment load was transported during streamflows greater than the National Weather Service flood action stage at the upstream sites (0.1–5 percent of the record; Cottonwood mean: 48 percent; Burlingame mean: 40 percent; Neosho Rapids mean: 78 percent). Disproportionately large sediment loads were delivered during short periods of time, and localized efforts of stream erosion protection (streambank stabilization, riparian buffers) were likely to be overwhelmed. Precipitation frequency and intensity are projected to continue to increase in this region; therefore, future sediment reduction strategies that account for extreme episodic events may be beneficial. Changes to reservoir outflow management could also minimize sediment accumulation while still preserving flood control. Continued investigation of sediment reduction measures is necessary for future mitigation with the understanding that sedimentation rate is largely driven by high flows. Results from this study can be used to calibrate sediment models, explore sediment reduction strategies, highlight the importance of continued water-quality monitoring to determine effectiveness and changes in sediment transport, and assess the ability of John Redmond Reservoir to support designated uses into the future.

Synthetic aperture radar and optical mapping used to monitor change and replacement of Phragmites australis marsh in the Lower Mississippi River Delta, Louisiana

Released June 01, 2021 15:52 EST

2021, Open-File Report 2021-1046

Elijah W. Ramsey III, Amina Rangoonwala

Synthetic aperture radar (SAR) mapping of density as an enhancement of Phragmites australis optical live fractional cover (LFC) mapping was carried out in the lower Mississippi Delta during 2016 to 2019. Also, as part of the study, the replacement of P. australis with elephant-ear was analyzed. To that end, yearly maps from 2016 to 2019 of L-band SAR horizontal send, vertical receive (HV) data representing marsh density were produced for the lower Mississippi River Delta. The mapping indicated high local variability within broad yearly density change in P. australis marsh. LFC mapping indicated a similar pattern of broad yearly change. That overall density and LFC linear correspondence was confirmed with regressions of P. australis marsh HV-density data and optical-LFC data. Local differences reflected as high scatter in the plots. Based on those results, a combined LFC and HV-density assessment tracker of P. australis condition was developed. Major findings from the use of the trajectory tool were the high decrease in HV density from 2016 to 2017, the identification of severely degraded P. australis marsh and European P. australis marsh in some areas, and indications of linkage between the density decline from 2016 to 2017 and the elephant-ear replacement from 2018 to 2019. The trajectory tool application also indicated an inverse relationship between elephant-ear occurrence and HV-density changes from 2018 to 2019. A similar but weaker relationship was found between elephant-ear and LFC. These relationships may provide a means for early detection of replacement of P. australis marsh by elephant-ear and other unwanted plant species.

Distribution and demography of coastal cactus wrens (Campylorhynchus brunneicapillus) in southern San Diego County, California—2020 data summary

Released June 01, 2021 13:17 EST

2021, Data Series 1138

Suellen Lynn, Barbara E. Kus

Executive Summary

Surveys for coastal Cactus Wren (Campylorhynchus brunneicapillus) were done in 378 established plots in southern San Diego County in 2020, encompassing three genetic clusters (Otay, Lake Jennings, and Sweetwater/Encanto genetic clusters). Two surveys were completed at each plot between March 1 and July 31. Cactus Wrens were detected in 131 plots (35 percent of plots). This is a slight increase over the proportion of occupied plots in 2019. One hundred and nine Cactus Wren territories were detected across all survey plots in 2020, an increase from 83 in 2019. At least 85 percent of Cactus Wren territories were occupied by pairs, and 62 fledglings were observed in 2020.

There were 89 color-banded Cactus Wrens observed in 2020, 84 of which we could identify to individual. Adults of known age ranged from 1 to at least 6 years old. Adult Cactus Wrens moved on average 0.2 kilometers (km; maximum 3.8 km) from their 2019 territories to their 2020 territories. Cactus Wrens that fledged in 2019 moved on average 1.2 km (maximum 9.9 km) to their 2020 territories. No known-identity Cactus Wrens moved between genetic clusters from 2019 to 2020.

Vegetation at Cactus Wren plots typically was dominated by coastal sage scrub shrubs such as California sagebrush (Artemisia californica), lemonadeberry (Rhus integrifolia), California buckwheat (Eriogonum fasciculatum), and broom baccharis (Baccharis sarothroides). Very little dead or unhealthy cactus was observed within Cactus Wren survey plots. Thirty-eight percent of plots had at least 25 percent of the cactus crowded or overtopped by vines and shrubs. Non-native annual cover was greater than 25 percent at 35 percent of plots.

Material properties and triggering mechanisms of an andesitic lava dome collapse at Shiveluch Volcano, Kamchatka, Russia, revealed using the finite element method

Released June 01, 2021 07:36 EST

2021, Rock Mechanics and Rock Engineering

Cory S Wallace, Lauren Nicole Schaefer, Marlène C. Villeneuve

Shiveluch volcano (Kamchatka, Russia) is an active andesitic volcano with a history of explosive activity, dome extrusion, and structural collapse during the Holocene. The most recent major (> 1 km3) dome collapse occurred in November 1964, producing a ~ 1.5 km3 debris avalanche that traveled over 15 km from the vent and triggered a phreatic explosion followed by a voluminous (~ 0.8 km3) eruption of juvenile pyroclastic material. Seismic records suggest that the collapse was likely triggered by a magnitude 5.1 earthquake associated with the ascent of magma into the edifice. The geomechanical properties of the pre-1964 dome are unknown; accordingly, the mechanics of the collapse are poorly understood. This project employs numerical slope stability modeling using the finite element method to constrain probable ranges of geomechanical properties for the materials involved in the collapse, considering earthquake loading as the most likely triggering mechanism. Model results show good agreement with the 1964 collapse geometry considering Geological Strength Index and horizontal pseudo-static seismic coefficient ranges of 30–60 and 0.05–0.15 g, respectively, representing variably fractured and altered dome rocks under moderate earthquake loading, confirming that ground acceleration alone could have triggered the dome collapse. Deep-seated rotational sliding is the dominant failure mode, but local extension within the dome during failure appears to play an important role in the development of the collapse. The findings of this work allow for better forward modeling of potential future collapses, the results of which can be incorporated into regional hazard and risk assessments.

Perfluoroalkyl substances in plasma of smallmouth bass from the Chesapeake Bay Watershed

Released May 30, 2021 06:57 EST

2021, International Journal of Environmental Research and Public Health (11)

Vicki S. Blazer, Stephanie Gordon, Heather L. Walsh, Cheyenne R. Smith

Smallmouth bass Micropterus dolomieu is an economically important sportfish and within the Chesapeake Bay watershed has experienced a high prevalence of external lesions, infectious disease, mortality events, reproductive endocrine disruption and population declines. To date, no clear or consistent associations with contaminants measured in fish tissue or surface water have been found. Therefore, plasma samples from two sites in the Potomac River and two in the Susquehanna River drainage basins, differing in land-use characteristics, were utilized to determine if perfluoroalkyl substances were present. Four compounds, perfluorooctane sulphonic acid (PFOS), perfluoroundecanoic acid (PFUnA), perfluorodecanoic acid (PFDA) and perfluorododecanoic acid (PFDoA), were detected in every fish. Two additional compounds, perfluorooctane sulphonamide (PFOSA) and perfluorononanoic acid (PFNA), were less commonly detected at lower concentrations, depending on the site. Concentrations of PFOS (up to 574 ng/mL) were the highest detected and varied significantly among sites. No seasonal differences (spring versus fall) in plasma concentrations were observed. Concentrations of PFOS were not significantly different between the sexes. However, PFUnA and PFDoA concentrations were higher in males than females. Both agricultural and developed land-use appeared to be associated with exposure. Further research is needed to determine if these compounds could be affecting the health of smallmouth bass and identify sources.

Surface flow velocities from space: Particle image velocimetry of satellite video of a large, sediment-laden river

Released May 28, 2021 13:36 EST

2021, Frontiers in Water (3)

Carl J. Legleiter, Paul J. Kinzel

Conventional, field-based streamflow monitoring in remote, inaccessible locations such as Alaska poses logistical challenges. Safety concerns, financial considerations, and a desire to expand water-observing networks make remote sensing an appealing alternative means of collecting hydrologic data. In an ongoing effort to develop non-contact methods for measuring river discharge, we evaluated the potential to estimate surface flow velocities from satellite video of a large, sediment-laden river in Alaska via particle image velocimetry (PIV). In this setting, naturally occurring sediment boil vortices produced distinct water surface features that could be tracked from frame to frame as they were advected by the flow, obviating the need to introduce artificial tracer particles. In this study, we refined an end-to-end workflow that involved stabilization and geo-referencing, image preprocessing, PIV analysis with an ensemble correlation algorithm, and post-processing of PIV output to filter outliers and scale and geo-reference velocity vectors. Applying these procedures to image sequences extracted from satellite video allowed us to produce high resolution surface velocity fields; field measurements of depth-averaged flow velocity were used to assess accuracy. Our results confirmed the importance of preprocessing images to enhance contrast and indicated that lower frame rates (e.g., 0.25 Hz) lead to more reliable velocity estimates because longer capture intervals allow more time for water surface features to translate several pixels between frames, given the relatively coarse spatial resolution of the satellite data. Although agreement between PIV-derived velocity estimates and field measurements was weak (R2 = 0.39) on a point-by-point basis, correspondence improved when the PIV output was aggregated to the cross-sectional scale. For example, the correspondence between cross-sectional maximum velocities inferred via remote sensing and measured in the field was much stronger (R2 = 0.76), suggesting that satellite video could play a role in measuring river discharge. Examining correlation matrices produced as an intermediate output of the PIV algorithm yielded insight on the interactions between image frame rate and sensor spatial resolution, which must be considered in tandem. Although further research and technological development are needed, measuring surface flow velocities from satellite video could become a viable tool for streamflow monitoring in certain fluvial environments.

Systems-deposits-commodities-critical minerals table for the earth mapping resources initiative

Released May 28, 2021 11:40 EST

2020, Open-File Report 2020-1042

Albert H. Hofstra, Douglas Kreiner

To define and prioritize focus areas across the United States with resource potential for 35 critical minerals in a few years’ time, the U.S Geological Survey Earth Mapping Resources Initiative (Earth MRI) required an efficient approach to streamline workflow. A mineral systems approach based on current understanding of how ore deposits that contain critical minerals form and relate to broader geologic frameworks and the tectonic history of the Earth was used to satisfy this Earth MRI need. This report describes the rationale for, and structure of, a table developed for Earth MRI that relates critical minerals and principal commodities to the deposit types and mineral systems in which they are concentrated. The hierarchical relationship between systems, deposits, commodities, and critical minerals makes it possible to define and prioritize each system-based focus area once for all of the critical minerals that it may contain. This approach is advantageous because mineral systems are much larger than individual ore deposits and they generally have geologic features that can be “imaged” by the topographic, geologic, geochemical, and geophysical mapping techniques deployed by Earth MRI.

Flood-inundation maps for the Blue River near Red Bridge Road, Kansas City, Missouri, 2019

Released May 28, 2021 11:11 EST

2021, Scientific Investigations Report 2020-5057

David C. Heimann, Jonathon D. Voss, Paul H. Rydlund, Jr.

Digital flood-inundation maps for a 4.6-mile reach of the Blue River near Red Bridge Road in Kansas City, Missouri, were created by the U.S. Geological Survey (USGS), in cooperation with the City of Kansas City, Missouri. The flood-inundation maps, which can be accessed through the USGS Flood Inundation Mapping Program website at https://www.usgs.gov/mission-areas/water-resources/science/flood-inundation-mapping-fim-program, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage 06893195, Blue River at Red Bridge Road, Kansas City, Mo. Near-real-time stages at this streamgage may be obtained from the USGS National Water Information System at https://doi.org/10.5066/F7P55KJN or the Johnson County, Kansas, StormWatch Automated Local Elevation in Real Time Flood Warning System at https://www.stormwatch.com.

Flood profiles were computed for the Blue River reach by means of a one-dimensional model for simulating water-surface profiles with steady-state flow computations. The model was calibrated by using the current stage-streamflow relations at the upstream USGS streamgage 06893150, Blue River at Blue Ridge Boulevard Extension, Kansas City, Mo., and the downstream streamgage 06893500, Blue River at Kansas City, Mo.

The hydraulic model was then used to compute 37 water-surface profiles for flood stages at 1-foot (ft) intervals referenced to the streamgage datum and ranging from 11 ft, or near bankfull, to 47 ft at the reference streamgage 06893195. The upper stage for the map library exceeds the stage corresponding to the estimated 0.2-percent annual exceedance probability flood (500-year recurrence interval flood) in the model reach. The simulated water-surface profiles were then combined with a geographic information system digital elevation model with a maximum 10-centimeter vertical root mean square error and 4.0-ft horizontal resolution to delineate the area flooded at each water level.

The availability of these maps, along with real-time internet information regarding current stage from the USGS streamgage, will help guide emergency management personnel and residents in flood mitigation, preparedness and planning, flood-response activities such as evacuations and road closures, and any postflood recovery efforts.

Characterization of historical and stochastically generated climate and streamflow conditions in the Souris River Basin, United States and Canada

Released May 28, 2021 10:53 EST

2021, Scientific Investigations Report 2021-5044

Angela Gregory, Joel M. Galloway

The Souris River Basin is a 61,000-square-kilometer basin in the Provinces of Saskatchewan and Manitoba in Canada and the State of North Dakota in the United States. Greater than average snowpack during the winter of 2010–11, along with record-setting rains in May and June 2011, resulted in historically unprecedented flooding in the Souris River Basin. The severity of the 2011 flood led the United States and Canada to request a review of the operating plan for any improvements of reservoir operations and flood control measures in the basin, and the Souris River Basin Task Force was formed. The International Souris River Study Board was then formed in 2017 to carry out the recommendations of the Souris River Basin Task Force laid out in a plan of study. To support the International Souris River Study Board, the U.S. Geological Survey (USGS), in cooperation with the North Dakota State Water Commission and the International Joint Commission, used the previously developed unregulated and regulated streamflow models and data for stochastic streamflow in the Souris River Basin to characterize climate and streamflow and support selection of streamflow traces based on their characterization. Components of the original stochastic hydrology models and their outputs were used in this phase of the study to (1) characterize historical and stochastic climate and streamflow for the Souris River Basin, (2) disaggregate monthly stochastic streamflow spatially and temporally to meet the needs of the U.S. Army Corps of Engineers, Hydrologic Engineering Center, Reservoir System Simulation model for the Souris River Basin, and (3) discuss selection of disaggregated streamflow traces (simulations) using the characteristics of climate and streamflow. A trace is a time series of a stochastic variable such as streamflow, potential evapotranspiration, or precipitation.

To characterize climate conditions, precipitation, potential evapotranspiration (PET), and moisture deficit for the Souris River Basin and individual points at Rafferty, Grant Devine, and Lake Darling Reservoirs were determined annually and seasonally. The annual basin (November 1–October 31) precipitation for the 50-percent nonexceedance probability is 452 millimeters (mm). Spring (March–May) is the wettest season, followed by summer (June–August), fall (September–November), and winter (December–February). Annual moisture deficit was largest at Lake Darling Reservoir, followed by Rafferty Reservoir, and then Grant Devine Reservoir.

Annual maximum monthly mean streamflow was determined for the Souris River below Rafferty Reservoir, Saskatchewan (Canadian streamgage 05NB036); Long Creek near Noonan (above Boundary Reservoir), North Dakota (USGS streamgage 05113600); Moose Mountain Creek near Oxbow, Saskatchewan (Canadian streamgage 05ND004); the Souris River near Sherwood, N. Dak. (USGS streamgage 05114000); the Des Lacs River at Foxholm, N. Dak. (USGS streamgage 05116500); and the Souris River above Minot, N. Dak. (USGS streamgage 05117500). When the seasonal maximum monthly mean streamflows are evaluated in contrast to annual maximum monthly mean streamflows separated by their seasonal occurrence, summer months of annual maximum monthly mean streamflows have a higher 50-percent exceedance probability of streamflow compared to annual maximum monthly mean streamflows that occur in spring, seasonal maximum monthly mean streamflows that occur in spring, and seasonal maximum monthly mean streamflows that occur in summer. When annual maximum monthly mean streamflows in summer are compared to annual maximum monthly mean streamflows in spring, they are consistently higher in streamflow but occur in less than 4.2 percent of years. Evaluation of whether the annual maximum monthly mean streamflows that occur in summer can be described as a separate population from annual maximum monthly mean streamflows that occur in spring was outside the scope of this study, and the summer and spring annual maximum monthly mean streamflows were not tested for statistical differences in mean or variance. Further investigation of seasonal weather patterns that induce flooding could lead to a better understanding of the seasonal differences in flooding.

Long-term hydrologic drought was characterized by evaluating multiyear mean streamflow. Shorter averaging periods have greater streamflow variability than longer periods and hence have a wider range of values. As the averaging period is extended to a longer period, the variability of mean streamflow decreases, and the more extreme streamflow volumes seen in shorter averaging periods cannot be sustained. Stochastic streamflow time series were disaggregated spatially and temporally for use in a HEC–ResSim model. The combination of monthly and daily stochastic streamflow data was used to select traces with qualities that could be used to test alternatives focused on water supply, summer flooding, and apportionment.

Optimization of salt marsh management at the Edwin B. Forsythe National Wildlife Refuge, New Jersey, through use of structured decision making

Released May 28, 2021 10:44 EST

2021, Open-File Report 2021-1037

Hilary A. Neckles, James E. Lyons, Jessica L. Nagel, Susan C. Adamowicz, Toni Mikula, Paul M. Castelli, Virginia Rettig

Structured decision making is a systematic, transparent process for improving the quality of complex decisions by identifying measurable management objectives and feasible management actions; predicting the potential consequences of management actions relative to the stated objectives; and selecting a course of action that maximizes the total benefit achieved and balances tradeoffs among objectives. The U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service, applied an existing, regional framework for structured decision making to develop a prototype tool for optimizing tidal marsh management decisions at the Edwin B. Forsythe National Wildlife Refuge in New Jersey. Refuge biologists, refuge managers, and research scientists identified multiple potential management actions to improve the ecological integrity of 23 marsh management units within the refuge and estimated the outcomes of each action in terms of performance metrics associated with each management objective. Value functions previously developed at the regional level were used to transform metric scores to a common utility scale, and utilities were summed to produce a single score representing the total management benefit that could be accrued from each potential management action. Constrained optimization was used to identify the set of management actions, one per marsh management unit, that could maximize total management benefits at different cost constraints at the refuge scale. Results indicated that, for the objectives and actions considered here, total management benefits may increase consistently up to about \$980,000, but that further expenditures may yield diminishing return on investment. Potential management actions in optimal portfolios at total costs less than \$980,000 included applying sediment to the marsh surface to increase elevation in five marsh management units, digging runnels on the marsh surface to improve drainage in five marsh management units, and breaching roads and berms to improve tidal flow in five marsh management units. The potential management benefits were derived from expected reduction in the duration of surface flooding, improved capacity for marsh elevation to keep pace with sea-level rise and increases in numbers of spiders (as an indicator of trophic health), tidal marsh obligate birds, and wintering American black ducks. The prototype presented here does not resolve management decisions; rather, it provides a framework for decision making at the Edwin B. Forsythe National Wildlife Refuge that can be updated as new data and information become available. Insights from this process may also be useful to inform future habitat management planning at the refuges.

Amplified impact of climate change on fine-sediment delivery to a subsiding coast, Humboldt Bay, California

Released May 28, 2021 07:19 EST

2021, Estuaries and Coasts

Jennifer Curtis, Lorraine E. Flint, Michelle A. Stern, Jack Lewis, Randy D. Klein

In Humboldt Bay, tectonic subsidence exacerbates sea-level rise (SLR). To build surface elevations and to keep pace with SLR, the sediment demand created by subsidence and SLR must be balanced by an adequate sediment supply. This study used an ensemble of plausible future scenarios to predict potential climate change impacts on suspended-sediment discharge (Qss) from fluvial sources. Streamflow was simulated using a deterministic water-balance model, and Qss was computed using statistical sediment-transport models. Changes relative to a baseline period (1981–2010) were used to assess climate impacts. For local basins that discharge directly to the bay, the ensemble means projected increases in Qss of 27% for the mid-century (2040–2069) and 58% for the end-of-century (2070–2099). For the Eel River, a regional sediment source that discharges sediment-laden plumes to the coastal margin, the ensemble means projected increases in Qss of 53% for the mid-century and 99% for the end-of-century. Climate projections of increased precipitation and streamflow produced amplified increases in the regional sediment supply that may partially or wholly mitigate sediment demand caused by the combined effects of subsidence and SLR. This finding has important implications for coastal resiliency. Coastal regions with an increasing sediment supply may be more resilient to SLR. In a broader context, an increasing sediment supply from fluvial sources has global relevance for communities threatened by SLR that are increasingly building resiliency to SLR using sediment-based solutions that include regional sediment management, beneficial reuse strategies, and marsh restoration.

Use of the smeltCam as an efficient fish sampling alternative within the San Francisco Estuary

Released May 28, 2021 07:04 EST

2021, San Francisco Estuary and Watershed Science (19)

Brock Huntsman, Frederick Feyrer, Matthew Young

Resource managers often rely on long-term monitoring surveys to detect trends in biological data. However, no survey gear is 100% efficient, and many sources of bias can be responsible for detecting or not detecting biological trends. The SmeltCam is an imaging apparatus developed as a potential sampling alternative to long-term trawling gear surveys within the San Francisco Estuary, California, to reduce handling stress on sensitive species like the Delta Smelt (Hypomesus transpacificus). Although believed to be a reliable alternative to closed cod-end trawling surveys, no formal test of sampling efficiency has been implemented using the SmeltCam. We used a paired deployment of the SmeltCam and a conventional closed cod-end trawl within the Napa River and San Pablo Bay, a Bayesian binomial N-mixture model, and data simulations to determine the sampling efficiency of both deployed gear types to capture a Delta Smelt surrogate (Northern Anchovy, Engraulis mordax) and to test potential bias in our modeling framework. We found that retention efficiency—a component of detection efficiency that estimates the probability a fish is retained by the gear, conditional on gear contact—was slightly higher using the SmeltCam (mean = 0.58) than the conventional trawl (mean = 0.47, Probability SmeltCam retention efficiency > trawl retention efficiency = 94%). We also found turbidity did not affect the SmeltCam’s retention efficiency, although total fish density during an individual tow improved the trawl’s retention efficiency. Simulations also showed the binomial model was accurate when model assumptions were met. Collectively, our results suggest the SmeltCam to be a reliable alternative to sampling with conventional trawling gear, but future tests are needed to confirm whether the SmeltCam is as reliable when applied to taxa other than Northern Anchovy over a greater range of conditions.

Ten years of volcanic activity at Mt Etna: High-resolution mapping and accurate quantification of the morphological changes by Pleiades and Lidar data

Released May 28, 2021 06:52 EST

2021, International Journal of Applied Earth Observations and Geoinformation (102)

Marina Bisson, Claudia Spinetti, Daniele Andronico, Monica Palaseanu-Lovejoy, Maria Fabrizia Buongiorno, Oleg Alexandrov, Thomas Cecere

The topography of Mt. Etna, Italy, is subjected to continuous modifications depending on intensity and magnitude of eruptions that frequently occur at the volcano summit and flanks. In order to make high-resolution maps of morphological changes and accurately calculate the overall volume of the erupted products (e.g., lava flows, tephra fall out, scoriae cones) in ten years, we have compared the altimetry models of Mt. Etna derived from 2005 Airborne Laser Scanning data and 2015 Pleiades stereo satellite imagery. Both models cover a common area of 400 km2 with spatial resolution of 2 m and comparable vertical accuracy (RMSE < 0.8 m). The results show that the area most affected by the erupted products is the mid-upper portion of the volcano with an altitude ranging from 1300 m to more than 3300 m a.s.l., value reached at the summit of the North East crater. In particular, this portion changes dramatically in the eastern sector due to the birth and growth of the New South-East Crater, the invasion of dozens of lava flows in the Valle del Bove, and the formation of the 2014 scoriae cones and lava field at the base of the North-East Crater. The total volume of products erupted in the investigated period results in 284.3±15.8 x 106 m3 with a yearly average volume of 28.4 x 106 m3/y comparable with the previous decades. In addition, the products emitted by the 2014 sub-terminal eruption are mapped and quantified including, for the first time, the volume of the 2014 scoriae cones generated on the eastern flank of North-East Crater This study demonstrates how a rigorous comparison between digital elevation models derived from different remote sensing techniques produce high accurate mapping and quantifications of morphological changes applicable for worldwide active volcanoes. This allows to quantify volumes and areas of erupted products reducing the error estimations, a crucial point to provide precise data often used as key parameters for many volcanic hazard studies.

Overview and methodology for a study to identify fecal contamination sources using microbial source tracking in seven embayments on Long Island, New York

Released May 27, 2021 18:19 EST

2021, Scientific Investigations Report 2021-5033

Tristen N. Tagliaferri, Shawn C. Fisher, Christopher M. Kephart, Natalie Cheung, Ariel P. Reed, Robert J. Welk

Between June 2018 and July 2019, the U.S. Geological Survey collaborated with the New York State Department of Environmental Conservation to analyze water quality in seven embayments on Long Island, New York, for a study to examine fecal contamination using microbial source tracking. This report documents the approach, methodology, and quality-assurance data used in the study. All samples and field data were collected in accordance with U.S. Geological Survey National Field Manual procedures. Samples were analyzed for host-specific deoxyribonucleic acid (DNA) markers, fecal coliform bacteria, inorganic and total organic nitrogen, and stable isotopes of nitrate and ammonium.

Samples for quality control were collected for microbiological analyses at a rate of 1 per 20 environmental samples. A total of 14 blank and 15 replicate samples were collected for DNA markers, 52 sequential field replicates were analyzed by the Public Environmental Health Laboratory of the Suffolk County Department of Health Services and the New York State Department of Conservation Marine Laboratory for fecal coliform, and 7 blank and 7 replicate samples were collected to be analyzed for nutrients. Results from quality-control samples collected throughout the course of the study confirmed that sampling procedures were adequate and did not disqualify any data from analysis.

Appendix C: Central sands lakes study technical report: Modeling documentation

Released May 27, 2021 08:51 EST

2021, Report

Michael N. Fienen, Megan J. Haserodt, Andrew T. Leaf, Stephen, M. Westenbroek

This report provides the necessary documentation of the numerical models developed for the Central Sands Lake study in central Wisconsin and will be included as a technical appendix in the report to the Wisconsin State Legislature by the Wisconsin Department of Natural Resources (WDNR) in response to 2017 Wisconsin Act 10. This legislation directed WDNR to determine whether existing and potential groundwater withdrawals are causing or are likely to cause significant reduction of mean seasonal water levels at Pleasant Lake, Long Lake, and Plainfield Lake (s. 281.34(7m)(2)(b), Wis. Stats.) in Waushara County, Wisconsin. To evaluate the potential hydrologic connection between groundwater withdrawals and the nearby study lakes, hydrologic models were created that focused on the lakes of interest and yet were large enough to cover a broad enough region to extend to the major hydrologic boundaries of the natural flow system. The areas near the lakes require finer-scale grid discretization (or spacing) to better represent the lakes and streams in the model, but also need to cover a large enough area to include the groundwater withdrawal locations that have the potential to cause reduction in water levels in the lakes. To accomplish these goals, three groundwater models were created: a regional model extending to major hydrologic boundaries; and two inset models, inheriting boundaries from the regional model but focused near the lakes. Each of the inset models, in turn, included a detailed area close to the lakes surrounded by an area at the same spatial scale as the regional model (Figure 1).

To support WDNR in evaluating the connection between groundwater withdrawals and lake levels, a representative time period was required over which to compare land use with and without irrigated agriculture and for WDNR to evaluate potential lake stage and flux changes related to irrigated agriculture. WDNR chose the climate period of 1981-2018 to be representative of a typical period and provided two land use scenarios—one with no irrigated agriculture and one with assumed crop rotations similar to current conditions—to simulate with groundwater models to, then, compare lake responses with. As a result, simulations over this climate record are not intended to recreate the history of 1981-2018 because land use changed over that time. These runs are, instead, intended to provide a basis on which to compare land use with and without irrigation-related groundwater withdrawals based on the current arrangement of land use and a varied climatic record. Groundwater withdrawals focused on irrigated-agriculture-related water use because greater than 95% of groundwater withdrawal in the two inset models around the study lakes is for irrigated agriculture water use.

The period of 2012-2018 was used for parameter estimation (synonymously referred to as “history matching”) for the groundwater models. This time period was chosen because it includes the most complete water use records to simulate groundwater withdrawals. History matching was performed using groundwater elevations, lake stages, and streamflow observations over the 2012-2018 time period and processed observations derived from those raw data.

Climatic data were incorporated into the model using a soil-water balance approach. A soil water balance model was constructed at the scale of the regional groundwater model to both calculate recharge based on land use and climate, and in the long-term climate-period runs, to estimate water use required by irrigated agriculture to apply as well boundary conditions in the groundwater model in the absence of reported water use values over that period.

Transient disease dynamics across ecological scales

Released May 27, 2021 08:12 EST

2021, Theoretical Ecology

Yun Tao, Jessica L Hite, Kevin D. Lafferty, David J D Earn, Nita Bharti

Analyses of transient dynamics are critical to understanding infectious disease transmission and persistence. Identifying and predicting transients across scales, from within-host to community-level patterns, plays an important role in combating ongoing epidemics and mitigating the risk of future outbreaks. Moreover, greater emphases on non-asymptotic processes will enable timely evaluations of wildlife and human diseases and lead to improved surveillance efforts, preventive responses, and intervention strategies. Here, we explore the contributions of transient analyses in recent models spanning the fields of epidemiology, movement ecology, and parasitology. In addition to their roles in predicting epidemic patterns and endemic outbreaks, we explore transients in the contexts of pathogen transmission, resistance, and avoidance at various scales of the ecological hierarchy. Examples illustrate how (i) transient movement dynamics at the individual host level can modify opportunities for transmission events over time; (ii) within-host energetic processes often lead to transient dynamics in immunity, pathogen load, and transmission potential; (iii) transient connectivity between discrete populations in response to environmental factors and outbreak dynamics can affect disease spread across spatial networks; and (iv) increasing species richness in a community can provide transient protection to individuals against infection. Ultimately, we suggest that transient analyses offer deeper insights and raise new, interdisciplinary questions for disease research, consequently broadening the applications of dynamical models for outbreak preparedness and management.

Long-term shedding from fully convalesced individuals indicates that Pacific herring are a reservoir for viral hemorrhagic septicemia virus

Released May 27, 2021 07:10 EST

2021, Diseases of Aquatic Organisms (144) 245-252

Paul Hershberger, Ashley Mackenzie, Jacob L. Gregg, M. D. Wilmot, Rachel L. Powers, Maureen K. Purcell

Processes that allow viral hemorrhagic septicemia (VHS) virus to persist in the marine environment remain enigmatic, owing largely to the presence of covert and cryptic infections in marine fishes during typical sub-epizootic periods. As such, marine host reservoirs for VHS virus have not been fully demonstrated, nor have the mechanism(s) by which infected hosts contribute to virus perpetuation and transmission. Here, we demonstrate that after surviving VHS, convalesced Pacific herring continue to shed virus at a low rate for extended periods. Further, exposure of previously naïve conspecific sentinels to this shed virus can result in infections for at least 6 mo after cessation of overt disease. This transmission mechanism was not necessarily dependent on the magnitude of the disease outbreak, as prolonged transmission occurred from 2 groups of donor herring that experienced cumulative mortalities of 4 and 29%. The results further suggest that the virus persists in association with the gills of fully recovered individuals, and long-term viral shedding or shedding relapses are related to cooler or decreasing water temperatures. These results provide support for a new VHS virus perpetuation paradigm in the marine environment, whereby the virus can be maintained in convalesced survivors and trafficked from these carriers to sympatric susceptible individuals.

Flow characteristics and salinity patterns in tidal rivers within the northern Ten Thousand Islands, southwest Florida, water years 2007–19

Released May 26, 2021 13:37 EST

2021, Scientific Investigations Report 2021-5028

Amanda C. Booth, Travis M. Knight

Freshwater flow to the Ten Thousand Islands (TTI) estuary has been altered by the construction of the Tamiami Trail and construction of features in the now defunct Southern Golden Gate Estates development. This development included four associated canals that combine into the Faka Union Canal, which discharges into the TTI estuary. The Picayune Strand Restoration Project (PSRP) was initiated in 2007 to improve freshwater delivery to the TTI estuary by removing hundreds of miles of roads, emplacing hundreds of canal plugs, removing exotic vegetation, and constructing three pump stations. Quantifying the tributary flows and salinity patterns prior to, during, and after the restoration is essential to assessing the effectiveness of upstream restoration efforts. The U.S. Geological Survey, in cooperation with U.S. Army Corps of Engineers, initiated an ongoing study in 2006 to assess flow and salinity patterns in the TTI estuary. This is the second report by the U.S. Geological Survey describing flow characteristics and salinity patterns in the TTI area as part of the PSRP. This report describes flow characteristics and salinity patterns for the monitoring stations at Faka Union River, Pumpkin River, and East River and includes an assessment of salinity data from the Faka Union Boundary and Blackwater River water-quality stations for water years 2007–19. A water year is defined as the 12-month period from October 1 for any given year to September 30 of the following year.

Annual and monthly variations in flow and salinity are often related to variations in rainfall with high and low annual flows (and below average and above average salinities) typically occurring during years with high and low annual rainfall, respectively. Monthly flows typically begin increasing in June and peak in September. Over the study period, positive trends in rainfall-adjusted monthly flow were detected at Faka Union River and East River, whereas no significant trend in flow was detected at Pumpkin River. Faka Union River is the largest contributor of freshwater to the TTI estuary, providing over 80 percent of the annual freshwater inflow to the estuary. The Faka Union Canal is expected to be the largest contributor of freshwater because until the PSRP is completed, the Faka Union Canal receives substantial drainage from multiple canals, which is not the case for Pumpkin and East Rivers. East River was the second largest contributor, followed by Pumpkin River. East River is downstream of the Fakahatchee Stand, which is a larger contributing area than the current contributing area for Pumpkin River. Monthly mean salinities were lowest at Faka Union River and East River, indicating that they received a greater amount of freshwater than the stations to the west. Negative trends in rainfall-adjusted salinity monthly means were observed at all monitoring stations during the study period. Increased trends in flow and decreased trends in salinity are attributed to increases in flow from upstream canals.

Seismic wave propagation and basin amplification in the Wasatch Front, Utah

Released May 26, 2021 08:16 EST

2021, Seismological Research Letters

Morgan P. Moschetti, David Henry Churchwell, Eric M. Thompson, John Rekoske, Emily Wolin, Oliver S. Boyd

Ground‐motion analysis of more than 3000 records from 59 earthquakes, including records from the March 2020 MwMw 5.7 Magna earthquake sequence, was carried out to investigate site response and basin amplification in the Wasatch Front, Utah. We compare ground motions with the Bayless and Abrahamson (2019; hereafter, BA18) ground‐motion model (GMM) for Fourier amplitude spectra, which was developed on crustal earthquake records from California and other tectonically active regions. The Wasatch Front records show a significantly different near‐source rate of distance attenuation than the BA18 model, which we attribute to differences in (apparent) geometric attenuation. Near‐source residuals show a period dependence of this effect, with greater attenuation at shorter periods (T<0.5  sT<0.5  s) and a correlation between period and the distance over which the discrepancy manifests (2050  km∼20–50  km). We adjusted the recorded ground motions for these regional path effects and solved for station site terms using linear mixed‐effects regressions, with groupings for events and stations. We analyzed basin amplification by comparing the site terms with the basin geometry and basin depths from two seismic‐velocity models for the region. Sites over the deeper parts of the sedimentary basins are amplified by factors of 3–10, relative to sites with thin sedimentary cover, with greater amplification at longer periods (T1  sT≳1  s). Average ground‐motion variability increases with period, and long‐period variability exhibits a slight increase at the basin edges. These results indicate regional seismic wave propagation effects requiring further study, and potentially a regionalized GMM, as well as highlight basin amplification complexities that may be incorporated into seismic hazard assessments.

Initial estimates of net infiltration and irrigation from a soil-water-balance model of the Mississippi Embayment Regional Aquifer Study Area

Released May 26, 2021 08:07 EST

2021, Open-File Report 2021-1008

Stephen, M. Westenbroek, Martha G. Nielsen, David E. Ladd

The Mississippi embayment encompasses about 100,000 square miles and covers parts of eight States. In 2016, the U.S. Geological Survey began updating previous work for a part of the embayment known as the Mississippi Alluvial Plain to support informed water use and agricultural policy in the region. Groundwater, water use, economic, and other related models are being combined with field surveys and observations to create a quantitative framework for evaluating regional groundwater withdrawals and their effects on long-term water availability in the Mississippi Alluvial Plain.

As part of this effort, the U.S. Geological Survey’s Soil-Water-Balance code (version 2.0) is being used to model potential groundwater recharge and irrigation water use, as necessary inputs to the long-term groundwater modeling efforts. The Soil-Water-Balance code is designed to estimate the distribution and timing of net infiltration leaving the root zone. Soil-Water-Balance makes use of gridded datasets of elevation, soils, land use (including specific crop types), and daily weather datasets to calculate other components of the root-zone water balance, including soil moisture, reference, actual evapotranspiration, snowfall, snowmelt, and canopy interception. Parameters on plant height and growing-season water needs are used to estimate crop-water demand and potential irrigation water use.

This report documents the initial construction, calibration, and application of a Soil-Water-Balance model of the Mississippi Embayment Regional Aquifer Study area for simulations running from 1915 to 2017. Further refinements of the model calibration for an expanded model area are planned.

Arsenic in petroleum-contaminated groundwater near Bemidji, Minnesota is predicted to persist for centuries

Released May 26, 2021 07:25 EST

2021, Water (13)

Brady A. Ziegler, G.-H. Crystal Ng, Isabelle M. Cozzarelli, Aubrey J. Dunshee, Madeline E. Schreiber

We used a reactive transport model to investigate the cycling of geogenic arsenic (As) in a petroleum-contaminated aquifer. We simulated As mobilization and sequestration using surface complexation reactions with Fe(OH)3 during petroleum biodegradation coupled with Fe-reduction. Model results predict that dissolved As in the plume will exceed the U.S. and EU 10 µg/L drinking water standard for ~400 years. Non-volatile dissolved organic carbon (NVDOC) in the model promotes As mobilization by exerting oxygen demand, which maintains anoxic conditions in the aquifer. After NVDOC degrades, As re-associates with Fe(OH)3 as oxygenated conditions are re-established. Over the 400-year simulation, As transport resembles a “roll front” in which: (1) arsenic sorbed to Fe(OH)3 is released during Fe-reduction coupled to petroleum biodegradation; (2) dissolved As resorbs to Fe(OH)3 at the plume’s leading edge; and (3) over time, the plume expands, and resorbed As is re-released into groundwater. This “roll front” behavior underscores the transience of sorption as an As attenuation mechanism. Over the plume’s lifespan, simulations suggest that As will contaminate more groundwater than benzene from the oil spill. At its maximum, the model simulates that ~5.7× more groundwater will be contaminated by As than benzene, suggesting that As could pose a greater long-term water quality threat than benzene in this petroleum-contaminated aquifer.

Status and understanding of groundwater quality in the northern Sierra Nevada foothills domestic-supply aquifer study units, 2015–17—California GAMA Priority Basin Project

Released May 25, 2021 15:11 EST

2021, Scientific Investigations Report 2021-5019

Zeno F. Levy, Miranda S. Fram

Groundwater quality in the northern Sierra Nevada foothills region of California was investigated as part of California State Water Resources Control Board (SWRCB) Groundwater Ambient Monitoring Assessment Priority Basin Project (GAMA-PBP). The region was divided into two study units: the Yuba-Bear watersheds (YBW) study unit and the American-Cosumnes-Mokelumne watersheds (ACMW) study unit. The GAMA-PBP made a spatially unbiased assessment of aquifer systems used for domestic drinking-water supply in the study region, which are predominantly composed of fractured, hard-rock aquifers of varying lithology. These assessments characterized the quality of raw groundwater to evaluate ambient conditions in the domestic-supply aquifer and not the quality of treated drinking water.

The study included three components: (1) a status assessment, which characterized the quality of groundwater resources used for domestic drinking-water supply in the YBW and ACMW study units; (2) an understanding assessment, which evaluated natural and anthropogenic explanatory factors that could potentially affect groundwater quality in the study region; and (3) a comparative assessment between the groundwater resources used for domestic and public drinking-water supply in the study region.

The status assessment was based on data collected by the GAMA-PBP from 74 sites in the YBW study unit during 2015–16 and 67 sites in the ACMW study unit from 2016 to 2017. To contextualize water-quality results, concentrations of water-quality constituents in ambient groundwater were compared to regulatory and non-regulatory benchmarks typically used by the State of California and Federal agencies as health-based or aesthetic standards for public drinking water. The status assessment used a grid-based method to estimate proportions of groundwater resources with concentrations approaching or exceeding benchmark thresholds. This method provides spatially unbiased results and allows inter-comparability with similar groundwater-quality assessments.

Inorganic constituents with health-based benchmarks were present at high relative concentration (RC), meaning they exceeded the benchmark threshold, in 5.4 and 10 percent of domestic-supply aquifer systems in the YBW and ACMW study units, respectively. Inorganic constituents with aesthetic-based benchmarks were detected at high-RCs in 20 and 28 percent of the YBW and ACMW study units, respectively. The inorganic constituents present at high RC were arsenic, barium, boron, molybdenum, strontium, nitrate, adjusted gross-alpha particle activity, chloride, total dissolved solids, specific conductance, iron, manganese, and hardness. Groundwater samples were tested for presence or absence of three microbial indicators (total coliform, Escherichia coli, and Enterococci). At least one microbial indicator was present in 26 and 28 percent of the YBW and ACMW study units, respectively. At least one organic constituent was detected in 30 and 42 percent of the YBW and ACMW study units, respectively. Organic constituents were not present at high RC, but tetrachloroethene (PCE), trichloroethene (TCE), and toluene were detected in the YBW study unit at moderate RC (between the benchmark concentration and one-tenth of the benchmark concentration). Methyl tert-butyl ether (MTBE) and chloroform were present at low RC (less than one-tenth of the benchmark concentration) in the YBW and ACMW study units with detection frequencies greater than 10 percent. Perchlorate, a constituent of special interest, was detected in 31 and 41 percent of the YBW and ACMW study units, respectively, at either low or moderate RCs.

Relations among select water-quality constituents and potential explanatory factors were evaluated using statistical and graphical approaches. Nitrate, microbial indicators, and perchlorate were all correlated to elevation-dependent variables relating to climate, land use, and recharge condition. Isotopic and dissolved noble-gas tracers indicated these water-quality constituents are associated with recharge conditions associated with irrigation during the summer dry-season, which is common in areas of rural-residential or agricultural land uses. Higher concentrations of iron and manganese were primarily associated with anoxic groundwater in aquifers of metasedimentary lithology. Increased hardness was primarily associated with anoxic groundwater in aquifers of mafic-ultramafic or metavolcanics lithologies at lower elevations in the study region in the Melones fault zone. Chloroform and MTBE were associated with shallow groundwater (wells depths less than 130 m) under oxic and anoxic redox conditions, respectively.

The comparative assessment evaluated differences between the aquifer systems used for domestic- and public-supply in study region based on (1) well-construction characteristics, and (2) water quality. Analysis of over 60,000 well-completion reports in the study region showed that although domestic-supply wells span the deepest depth zones in regional aquifers, median depths for public-supply wells were significantly greater than those of domestic-supply wells in both study units. Water-quality data from more than 300 public-supply wells in the study region were assessed using a spatially weighted method for calculation aquifer-scale proportions and compared with the domestic-supply assessment results. Detections of inorganic constituents at high RC and detection frequencies for organic constituents were generally similar between the domestic- and public-supply aquifer systems in both study units, with a few notable exceptions in the ACMW study unit: nitrate was greater for the public- compared to domestic-supply aquifer system and both manganese, hardness, and MTBE were greater in the domestic- compared to public-supply aquifer system. These differences are likely related to contrasting land uses, aquifer lithologies, landscape positions, and depths characterizing domestic- and public-supply wells in the ACMW study unit.

Overall, fewer samples from domestic-supply wells in the northern Sierra Nevada foothills exceeded health-based benchmarks compared to aesthetic-based benchmarks for groundwater quality. Exceedences of health-based benchmarks were primarily caused by nitrate and coliform bacteria, which were associated with recharge from diverted surface water used primarily for irrigation. Exceedences of aesthetic-based benchmarks were primarily caused by iron, managanese, and hardness, which were associated with geologic factors. Regional irrigation practices and aquifer lithology can affect groundwater quality in fractured-rock aquifers in the northern Sierra Nevada foothills used for domestic drinking-water supply.

Geologic influences on the quality of groundwater used for domestic supply in the northern Sierra Nevada Foothills

Released May 25, 2021 15:11 EST

2021, Fact Sheet 2021-3013

Zeno F. Levy, Miranda S. Fram

Approximately 2 million California residents depend on groundwater from domestic wells for their drinking-water supply. The State of California, in collaboration with the U.S. Geological Survey, created the Groundwater Ambient Monitoring and Assessment Program Priority Basin Project (GAMA-PBP) to assess the quality of groundwater used for domestic supply throughout the state and determine regional vulnerabilities to drinking-water resources. Many rural households in the northern Sierra Nevada foothills (hereafter referred to as “the foothills”) use domestic wells that pump water from fractured-bedrock aquifers. In the foothills, complicated and varied regional bedrock geology can cause substantial variation in groundwater chemistry and quality over relatively short distances. This factsheet presents findings from the GAMA-PBP assessment that highlight influences of geologic factors on groundwater quality in the foothills.

Sampling for Per- and Polyfluoroalkyl Substances (PFAS) by the Groundwater Ambient Monitoring and Assessment Priority Basin Project

Released May 25, 2021 14:43 EST

2021, Fact Sheet 2021-3028

Robert H. Kent

Per- and polyfluoroalkyl substances (PFAS) are a family of human-made chemicals that can persist in the environment. In 2019, the California State Water Resources Control Board’s Groundwater Ambient Monitoring and Assessment Priority Basin Project (GAMA-PBP) added PFAS to the projects’ on-going assessments of the quality of groundwater used for drinking-water supplies. This fact sheet describes the GAMA-PBP plans for sampling public-supply and domestic wells across California for PFAS and presents preliminary results for data collected in 2019–20.

Hydrologic and hydraulic analyses of selected streams near the city of Rittman in Wayne and Medina Counties, Ohio

Released May 25, 2021 14:01 EST

2021, Scientific Investigations Report 2021-5040

Chad J. Ostheimer

The U.S. Geological Survey, in cooperation with the Muskingum Watershed Conservancy District and the city of Rittman, Ohio, did a study to provide data to update and expand parts of two Federal Emergency Management Agency Flood Insurance Studies. The study consisted of hydrologic and hydraulic analyses for selected reaches of four streams (Chippewa Creek, Little Chippewa Creek, Styx River, and the unnamed tributary to Styx River) near the city of Rittman in Wayne and Medina Counties, Ohio. The study covered 36.2 miles of stream reaches.

Instantaneous peak streamflows for floods with 10-, 4-, 2-, 1-, and 0.2-percent and 1-percent plus annual exceedance probabilities were estimated using historical streamflow data from three U.S. Geological Survey streamgages and regional flood-frequency regression equations. The flood-frequency estimates were then used in a Hydrologic Engineering Center River Analysis System step-backwater model to determine water-surface profiles; flood-inundation boundaries for the 10-, 4-, 2-, 1-, and 0.2-percent and 1-percent plus annual exceedance probabilities; and a regulatory floodway for the study reaches. Model inputs included cross sections derived from a digital elevation model supplemented with field surveys of open-channel cross sections and hydraulic structures, field estimates of Manning’s roughness values, and flood estimates determined from regional regression equations and historical streamflow data. Flood-inundation boundaries were mapped for each stream reach for the 1- and 0.2-percent annual exceedance probability floods and a regulatory floodway. All data used in the creation of the flood-inundation boundaries are available through a U.S. Geological Survey data release (Ostheimer, 2021) and will be submitted to the Federal Emergency Management Agency for inclusion in updated Flood Insurance Studies for Wayne and Medina Counties.

Discharge data collection and analysis and implications for surface-water/groundwater interactions in the lower Las Vegas Wash, Clark County, Nevada, 2016–18

Released May 25, 2021 10:39 EST

2021, Scientific Investigations Report 2021-5034

Jon W. Wilson

The lower Las Vegas Wash represents the terminal surface drainage for the Las Vegas Valley in southern Nevada. In 1997, high concentrations of perchlorate were found in seeps contributing to discharge in this area and traced to an industrial byproduct from manufacturing operations in the mid-1900s at the nearby Basic Magnesium, Incorporated, plant. The discovery prompted a water-resources investigation by the Nevada Department of Environmental Protection (NDEP) to develop an understanding of the nearby groundwater flow system and the dynamics associated with surface-water flow in the Wash. In 2016, the U.S. Geological Survey was tasked with evaluating surface-water discharge in the lower Las Vegas Wash near locations where perchlorate concentrations from the groundwater system had been detected. Results of this study will assist NDEP with identifying areas of groundwater and surface-water interaction and help guide future cleanup and monitoring efforts.

Streamflow discharge is evaluated along a 4-mile section of the lower Las Vegas Wash (referred to as the Wash) and used to describe surface-water and groundwater interactions between the Wash channel and bank sediments. Continuous discharge data were collected during a 2-year period (2016–18) at 5 gaging stations along the Wash. Additionally, multiple discrete measurements between gaging stations were collected during 4 synoptic sampling events between 2016 and 2018.

A diurnal discharge pattern, controlled by upstream treated wastewater releases, provided high- and low-discharge markers that are used to compute downstream time-lags of peak and minimum flows. Computed time-lags are used to establish travel times between measurement sites, and difference in upstream and time-lagged downstream hydrographs are used to compute increases (gain) or decreases (loss) in discharge between gaging stations or between gaging stations and discrete measurements. Tributary surface-water inflows to the lower Las Vegas Wash from wastewater discharge, remediation efforts, and periodic flooding from rainfall runoff are included in computing differences in discharge. Differences between discharge data from delineated reaches are used to define locations of daily, monthly, and yearly streamflow gains from or losses to adjacent bank sediments. Construction of additional channel-stabilization weirs have occurred since the completion of this study and the associated change to streamflow dynamics may limit study results to the period analyzed; however, methods and processes described in this report can be used in future evaluations.

Synthesizing and analyzing long-term monitoring data: A greater sage-grouse case study

Released May 25, 2021 07:40 EST

2021, Ecological Informatics (63)

Michael O'Donnell, David R. Edmunds, Cameron L. Aldridge, Julie Heinrichs, Adrian P. Monroe, Peter S. Coates, Brian G. Prochazka, Thomas J Christiansen, Steve E. Hanser, Lief A. Wiechman, Avery A Cook, Shawn P. Espinosa, Lee J. Foster, Kathleen A. Griffin, Jesse L Kolar, Katherine S Miller, Ann M. Moser, Thomas E. Remington, Travis J Runia, Leslie A Schreiber, Michael A Schroeder, San J Stiver, Nyssa I Whitford, Catherine S Wightman

Long-term monitoring of natural resources is imperative for increasing the understanding of ecosystem processes, services, and how to manage those ecosystems to maintain or improve function. Challenges with using these data may occur because methods of monitoring changed over time, multiple organizations collect and manage data differently, and monetary resources fluctuate, affecting many aspects of data. Because many species respond to changes in habitat conditions and predator-prey relationships across different spatial scales that span management boundaries, greater efforts for collaborating are essential. We demonstrate the challenges and methods for standardizing greater sage-grouse (Centrocercus urophasianus) long-term monitoring data across the species range in the western United States to inform population modeling needs identified by the Western Association of Fish and Wildlife Agencies. We used automated and repeatable methods of standardizing data via custom open-source software (grsg_lekdb) to improve the scientific integrity of future sage-grouse population assessments within and among states. Data standardization included reconciling uses of different terminology and expunging unusable data, resulting in the removal of 26% of data records due to database insertion errors and modifications to >1 million values to correct formatting and typing errors. Our approaches maximized the inclusion of usable data and identified data that could inform detection probabilities, population trends, and monitoring guidelines. Using sage-grouse databases as an example, we identified the importance of data management and how quality assurance and quality control measures can improve the usefulness of these data for future research needs. Our methods of using informatics and concluding recommendations can support similar endeavors of flora and fauna monitoring programs, whether those efforts are to use existing data or support new monitoring programs.

Western pond turtles in the Mojave Desert? A review of their past, present, and possible future

Released May 25, 2021 07:40 EST

2021, Vertebrate Zoology (71) 317-334

Jeffrey E. Lovich, George T. Jefferson, Robert E. Reynolds, Peter A. Scott, H. Bradley Shaffer, Shellie R. Puffer, Sarah Greely, Kristy L. Cummings, R. N. Fisher, Kathie Meyer-Wilkins, Doug Gomez, Morgan Ford, Christopher D Otahal

=

The western pond turtle (WPT) was formerly considered a single species (Actinemys or Emys marmorata) that ranged from southern British Columbia, Canada to Baja California, México. More recently it was divided into a northern and a southern species. WPTs are found primarily in streams that drain into the Pacific Ocean, although scattered populations exist in endorheic drainages of the Great Basin and Mojave deserts. Populations in the Mojave Desert were long thought to be restricted to the Mojave River, but recently another population was documented in Piute Ponds, a terminal wetland complex associated with Amargosa Creek on Edwards Air Force Base. WPT fossils in the Mojave Desert are known from the Miocene to the Pleistocene. Recently, Pleistocene fossils have been found as far into the desert as Salt Springs, just south of Death Valley. The oldest fossil records suggest that WPTs were present in wetlands and drainages of the geological feature known as the Mojave block prior to the uplift of the Sierra Nevada Range about 8 Ma and prior to the ~ 3 Ma uplift of the Transverse Ranges. Archaeological records document use of turtles by Native Americans for food and cultural purposes 1,000 or more years ago at the Cronese Lakes on the lower Mojave River and Oro Grande on the upper river. The first modern publication documenting their presence in the Mojave River was 1861. Museum specimens were collected as early as 1937. These fossil and early literature records support the indigenous status of WPTs to the Mojave River. However, mtDNA-based genetic evidence shows that Mojave River turtles share an identical haplotype with turtles on the California coast. Limited nuclear data show some minor differences. Overdraft of water from the Mojave River for municipal and agricultural uses, urban development, and saltcedar expansion are threats to the continued survival of WPTs in the Mojave River.

Do crayfish affect stream ecosystem response to riparian vegetation removal?

Released May 25, 2021 07:11 EST

2021, Freshwater Biology

Maura P. Dudley, Kelsey Solomon, Seth J. Wenger, C. Rhett Jackson, Mary Freeman, Katherine J. Elliott, Chelcy F. Miniat, Catherine M. Pringle

1. Riparian vegetation management alters stream basal resources, but stream ecosystem responses partly depend on top-down interactions with in-stream consumers. Large-bodied omnivores can exert particularly strong influences on stream benthic environments through consumption of food resources and physical disturbance of the benthos. Trophic dynamics studies conducted within the context of reach-scale riparian vegetation manipulations can provide insights into the interactions and relative importance of top-down and bottom-up controls that determine ecosystem response to riparian change. 2. Here, we examine how top-down control by crayfish omnivores (Cambarus spp.) interacts with abiotic conditions created by reach-scale removal of riparian rhododendron (Rhododendron maximum) in the southern Appalachian Mountains. We conducted 32-day trophic experiments by nesting 5 pairs of electrified (crayfish excluded) and non-electrified (crayfish access) plots within each of two 300-m stream reaches (one control and one rhododendron-removed) for one year pre-removal and two years post-removal. 3. Algal growth only responded positively to the reduced canopy cover (post-rhododendron removal) under low flow conditions and in the absence of top-down control by crayfish during the post-treatment year 2. Leaf decomposition rates were reduced by ~40% in the absence of crayfish, but higher inputs of rhododendron leaf litter during the summer following rhododendron removal reduced the effect of crayfish presence on decomposition. Riparian rhododendron removal also significantly increased benthic sediment and fine benthic organic matter, but macroconsumer exclusion did not affect these stream properties. 4. Potential long-term reductions in crayfish abundance could reduce the top-down effects of crayfish and ultimately lead to higher algal growth and reduced leaf decomposition rates in streams where rhododendron is managed through removal.

Time marches on, but do the causal pathways driving instream habitat and biology remain consistent?

Released May 24, 2021 07:29 EST

2021, Science of the Total Environment (789)

Richard H Walker, Matthew J. Ashton, Matthew J. Cashman, Rosemary Fanelli, Kevin P. Krause, Gregory B. Noe, Kelly O. Maloney

Stream ecosystems are complex networks of interacting terrestrial and aquatic drivers. To untangle these ecological networks, efforts evaluating the direct and indirect effects of landscape, climate, and instream predictors on biological condition through time are needed. We used structural equation modeling and leveraged a stream survey program to identify and compare important predictors driving condition of benthic macroinvertebrate and fish assemblages. We used data resampled 14 years apart at 252 locations across Maryland, USA. Sample locations covered a wide range of conditions that varied spatiotemporally. Overall, the relationship directions were consistent between sample periods, but their relative strength varied temporally. For benthic macroinvertebrates, we found that the total effect of natural landscape (e.g., elevation, longitude, latitude, geology) and land use (i.e., forest, development, agriculture) predictors was 1.4 and 1.5 times greater in the late 2010s compared to the 2000s. Moreover, the total effect of water quality (e.g., total nitrogen and conductivity) and habitat (e.g., embeddedness, riffle quality) was 1.2 and 4.8 times lower in the 2010s, respectively. For fish assemblage condition, the total effect of land use-land cover predictors was 2.3 times greater in the 2010s compared to the 2000s, while the total effect of local habitat was 1.4 times lower in the 2010s, respectively. As expected, we found biological assemblages in catchments with more agriculture and urban development were generally comprised of tolerant, generalist species, while assemblages in catchments with greater forest cover had more-specialized, less-tolerant species (e.g., Ephemeroptera, Plecoptera, and Trichoptera taxa, clingers, benthic and lithophilic spawning fishes). Changes in the relative importance of landscape and land-use predictors suggest other correlated, yet unmeasured, proximal factors became more important over time. By untangling these ecological networks, stakeholders can gain a better understanding of the spatiotemporal relationships driving biological condition to implement management practices aimed at improving stream condition.

Improved methods for understanding the role of predation on dreissenid population dynamics

Released May 24, 2021 07:14 EST

2021, Environmental Biology of Fishes (104) 629-633

Kevin R. Keretz, Richard Kraus, Joseph Schmitt

Impacts of dreissenid mussels (Dreissena spp.) on Great Lakes ecosystems are well documented, and a better understanding of mechanisms that cause variation in dreissenid abundance is needed. An outstanding question is how much dreissenid biomass is consumed by fish predation. A significant difficulty for investigating dreissenid consumption by fish is that dreissenids in stomachs are often a mix of indigestible shell and flesh, which can bias bioenergetics models and estimates of daily ration. Here, we develop an analysis to convert crushed shell and flesh mixtures found in fish diets to dry weight of digestible dreissenid flesh. Quagga Dreissena rostiformis bugensis and zebra Dreissena polymorpha mussels were used in separate dry weight analyses simulating stomach contents ranging from individual mussels to aggregates of each species. A species-specific dry weight relationship was observed when comparing flesh-only dry weight to total dry weight (shell + flesh) for individual dreissenid but not for aggregates. Thus, the model is applicable in providing more precise estimates of dreissenid flesh dry weight in fish diets.

Effect of groundwater withdrawals, river stage, and precipitation on water-table elevations in the Iowa River alluvial aquifer near Tama, Iowa, 2017–20

Released May 21, 2021 16:29 EST

2021, Open-File Report 2021-1019

Lance R. Gruhn, Adel E. Haj

The Sac and Fox Tribe of the Mississippi in Iowa is the only federally recognized Tribe in the State of Iowa and is commonly known as the Meskwaki Nation. The Tribe owns more than 8,100 acres, referred to as the “Meskwaki Settlement.” The Meskwaki Settlement uses a well field that withdraws water from the Iowa River alluvial aquifer (IRAA) to supply drinking water to members of the Tribe. Increased severity and timing of flooding and drought conditions, coupled with water-quality concerns in the Iowa River, have prompted the Meskwaki Nation to start identifying tools to provide a better understanding of how extreme climate events (changes in streamflow, flood frequency, and magnitude and persistence of drought conditions), increasing water-supply demands, and groundwater storage depletion will affect water availability in the IRAA.

From June 2017 through September 2020, the U.S. Geological Survey, in cooperation with the Meskwaki Nation, collected continuous and discrete groundwater level data from 11 wells in a U.S. Geological Survey monitoring-well network. Groundwater level data collected at these wells were assessed with daily precipitation data and compared to changes in stream level elevations and daily groundwater withdrawals to determine how these changes affect groundwater-table elevations. Results from this study could be used to guide the development of a conceptual model for groundwater flow and a groundwater flow model for the IRAA to quantify and forecast the effect of groundwater withdrawals, Iowa River streamflow, and local precipitation on the water table in the IRAA.

Improving flood-frequency analysis with a 4,000-year record of flooding on the Tennessee River near Chattanooga, Tennessee

Released May 21, 2021 09:15 EST

2021, Scientific Investigations Report 2020-5138

Tessa M. Harden, Jim E. O'Connor, Meredith L. Carr, Mackenzie Keith

This comprehensive field study applied paleoflood hydrology methods to estimate the frequency of low-probability floods for the Tennessee River near Chattanooga, Tennessee. The study combined stratigraphic records of large, previously unrecorded floods with modern streamflow records and historical flood accounts. The overall approach was to (1) develop a flood chronology for the Tennessee River near Chattanooga using stratigraphic analyses and geochronology from multiple sites at multiple elevations in the study area; (2) estimate peak flow magnitudes associated with elevations of flood evidence using a one-dimensional hydraulic model; (3) combine the information obtained from steps 1 and 2 to develop a history of timing and magnitude of large floods in the study reach; and (4) use all available information (including paleoflood, gaged, and historical records of flooding) to estimate flood frequency using a standardized statistical approach for flood-frequency analysis.

The stratigraphy, geochronology, and hydraulic modeling results from all paleoflood sites along the Tennessee River were distilled into an overall chronology of the number, timing, and magnitude of large unrecorded floods. In total, 30 sites were identified and the stratigraphy of 17 of those sites was closely examined, measured, and recorded. Flood-frequency analyses were done using the U.S. Geological Survey software program PeakFQ v7.2 that follows the Guidelines for Determining Flood Flow Frequency—Bulletin 17C.

Resolving stratigraphic and chronologic information from all 17 sites yielded information for eight unique large floods in the last 3,500–4,000 years for the Tennessee River near Chattanooga. Two of these floods had discharges of 470,000 cubic feet per second (ft3/s), slightly greater than the 1867 historical peak at the Chattanooga streamgage (459,000 ft3/s). One flood with a discharge of 1,100,000 ft3/s was substantially greater than any other flood on the Tennessee River during the last several thousand years. This large flood occurred only a few hundred years ago, likely in the mid-to-late 1600s. Two additional floods in the last 1,000 years had estimated magnitudes of about 420,000 and 400,000 ft3/s. The remaining three unique floods identified in the paleoflood record were much smaller (less than 240,000 ft3/s) and occurred about 3,000–800 years ago.

Flood-frequency analyses show that the addition of paleoflood information markedly improves estimates of low probability floods—most clearly shown by substantial narrowing of the 95-percent confidence limits. For the most plausible flood scenario, the 95-percent confidence interval for the 1,000-year quantile estimate derived from incorporating the four most recent paleofloods is about 480,000–620,000 ft3/s compared to about 380,000–610,000 ft3/s for the gaged and historical record alone, a reduction in the uncertainty of the estimate by 38 percent. Similarly, uncertainty for all flood quantile estimates from 100 to 10,000 years was reduced by 22–44 percent by the addition of the paleoflood record to the flood-frequency analyses.

Reconstructing paleohydrology in the northwest Great Basin since the last deglaciation using Paisley Caves fish remains (Oregon, U.S.A.)

Released May 21, 2021 08:34 EST

2021, Quaternary Science Reviews (262)

Adam M. Hudson, Meaghan M Emery-Wetherell, Patrick M Lubinski, Virginia L. Butler, Deanna N Grimstead, Dennis L Jenkins

The arid northwest Great Basin underwent substantial hydroclimate changes in the past 15,000 years, greatly affecting its desert ecosystems and prehistoric people. There are conflicting interpretations of the timing of hydrologic changes in this region, requiring more records to resolve the dominant climatic drivers. The Paisley Caves archaeological site, located near former pluvial Lake Chewaucan, contains well-dated, stratified sediments best known for evidence of early human occupation in North America. We present a novel paleohydrologic record for the Chewaucan basin based on the frequency of fish remains (Salmonidae and Cypriniformes, likely tui chub) and their carbon, oxygen, and strontium isotope compositions, from the Paisley Caves. Cypriniformes abundance peaks first at the start of the Bølling/Allerød warm interval (∼14.7 ka) and again during the early Younger Dryas (∼12.8 ka). Isotope compositions indicate tui chub were derived from an expansive Lake Chewaucan throughout the Bølling/Allerød, but mainly from spring- or stream-influenced sources by the late Younger Dryas to the present. Fish abundance dropped sharply through the Younger Dryas and early Holocene, when isotope compositions indicate a mix of habitats. Isotope compositions indicate the driest conditions during the middle Holocene, followed by slightly wetter conditions up to the present. This record agrees with recent pluvial lake reconstructions, supporting the hypothesis that a northward shift in the winter storm track supported deep lakes throughout the Bølling/Allerød in the northwest Great Basin. Lake level decline during the Younger Dryas suggests drying climate, differing from more southerly records. During the Holocene, however, shifts in Chewaucan basin hydrology are consistent with the rest of the western U.S. This highlights the need for region-specific records to inform predictions of the hydrologic impact of climate change on arid regions.

Establishment and survival of subalpine fir (Abies lasiocarpa) in meadows of Olympic National Park, Washington

Released May 21, 2021 07:29 EST

2021, Northwest Science (94) 256-270

Andrea Woodward, Jonathan A. Soll

Establishment of trees in subalpine meadows is a potential indicator of ecological effects of climate change. Tree establishment is a multi-year process including cone and seed production, germination, establishment, and growth, with each demographic step possibly sensitive to different climate limitations. While most studies have focused on one or a few steps, this study follows a cohort of individually marked saplings for 27 years beginning as seeds in two meadows on Hurricane Ridge, Olympic National Park. These meadows are examples of a south-facing tall sedge community type rather than the north-facing heath-shrub type where establishment has usually been observed. Results showed that mortality was high for the first few years, but number of saplings stabilized after the first decade. Seedling mortality during germination and establishment was directly related to weather that resulted in high air and soil temperatures and drought, while mortality of established saplings was indirectly related to weather through effects on growth. Growth was enhanced by longer growing season and warmer minimum temperatures; growth over three years and sapling height were predictive of mortality. Most sapling survival occurred in lichen (primarily Trapeliopsis granulosa) and Vaccinium deliciosum plant communities. Many saplings are growing at very low rates compared with the rate predicted from adult trees. It is also apparent that while microsite within meadow (e.g., relative snow depth) is important in determining sapling success, the landscape position of meadows (e.g., north versus south aspect) exerts a higher-level control over whether a subalpine meadow is likely to disappear with warming climate.

Sediment budget for watersheds of West Maui, Hawaii

Released May 21, 2021 07:16 EST

2021, Scientific Investigations Report 2020-5133

Jonathan D. Stock, Corina Cerovski-Darriau

Episodic runoff brings suspended sediment to West Maui’s nearshore waters, turning them from blue to brown. This pollution degrades the ecological, cultural, and recreational value of these iconic nearshore waters. We used mapping, monitoring, and modeling to identify and quantify the watershed sources for fine sediment that pollutes the nearshore each year. These results focus strategies to reduce pollution on the outstanding sources for this sediment.

Terrestrial runoff causing coastal plumes now occurs when two or more hours of rain falls at rates greater than 10–20 millimeter (mm) per hour in source watersheds. Analysis of recent and historical rainfall indicates that West Maui communities can expect rainfalls to bring coastal plumes at least 3–5 times per year. Former agricultural fields and some unimproved roads are possible sources for the fine sediment of these plumes. We found, however, that these obvious sources do not produce plumes during small annual storms, because they drain water at rates that far exceed most annual rainfalls and because there is no evidence for runoff from rains that caused recent plumes. Streambanks now eroding into historic fill terraces of sands, silts, and clays are a more plausible source. These terraces are found only downstream of historical agricultural fields and are composed of silt and fine sand. Surveys show that the fill terraces occupy ~40 percent of streambank length, making them extensive. During 2015–2016, these deposits eroded at median rates of 5–24 mm per year. Summed over West Maui’s watersheds, these rates imply sediment loads carried to the coast that can be ten times or more than modeled pre-human values. A sediment budget indicates that bank erosion of fill terraces from a few watersheds likely dominates the current annual fine-sediment load to the nearshore, with Kahana Stream watershed producing the largest annual input of 285 metric tons, the equivalent of 29 dump-truck loads every year.

Although past large storms have contributed to sediment loading, annual plume generation is now caused by smaller rainfalls eroding these near-stream terrace deposits, a legacy of historic agriculture. Treatments of former agricultural fields, roads, and reserve forests are consequently not likely to measurably effect sediment pollution from smaller, more frequent storms. Increased runoff from residential and commercial development of West Maui has the potential to exacerbate sediment plumes from such storms.

GIS-based identification of areas that have resource potential for sediment-hosted Pb-Zn deposits in Alaska

Released May 20, 2021 18:00 EST

2021, Open-File Report 2020-1147

Karen D. Kelley, Garth E. Graham, Keith A. Labay, Nora B. Shew

A state-wide Geographic Information System analysis was conducted to assess prospectivity for lead (Pb) and zinc (Zn) in sediment-hosted deposits in Alaska. The datasets that were utilized include publicly available geospatial datasets of lithologic, geochemical, and mineral occurrence data. Key characteristics of Pb-Zn deposits were identified in available datasets and scored with respect to relative importance. To evaluate resource potential, drainage basins of the smallest size were chosen, each of which covers approximately 100 square kilometers (km2). Drainage basins are the most logical and efficient unit for evaluation because the most regionally robust dataset comes from stream sediment geochemistry.

Sediment-hosted Pb-Zn deposits in Alaska include those contained in carbonate rocks (similar to Mississippi Valley Type or MVT deposits) and those contained in clastic-dominated (CD) sequences (CD Pb-Zn), historically referred to as SEDEX (sedimentary exhalative). The latter include the deposits currently being mined in the Red Dog district in the western Brooks Range. Host rocks for the two subtypes are distinct: carbonate versus fine-grained clastic rocks for CD Pb-Zn deposits. However, there are exceptions: some CD Pb-Zn deposits are hosted in carbonate layers within a thick clastic-dominated rock sequence. The statewide geologic map database contains units that commonly include mixed carbonate-clastic sequences that cannot be subdivided. The most significant difference between the two deposit types is their respective depositional environments and tectonic settings, but at the reconnaissance level of mapping in most areas of the state, these distinctions are not possible. Furthermore, nearly all critical geochemical parameters (silver [Ag], barium [Ba], Pb, Zn) are common to both types, and therefore it was not possible to do separate assessments for carbonate-hosted and CD Pb-Zn deposits.

Areas identified that have moderate to high potential for sediment-hosted Pb-Zn deposits include the (1) western and central Brooks Range, referred to in this report as the Brooks Range zinc belt; (2) Seward Peninsula (and adjacent St. Lawrence Island); (3) Farewell terrane in Interior Alaska; (4) two spatially distinct belts in east-central Alaska; and (5) the central Alaska Range. All areas contain some known deposits, and that provides credibility to the scoring process. Some hydrologic unit codes (HUCs) that have high potential for sediment-hosted Pb-Zn deposits are located adjacent to areas of known deposits and indicate the potential for expansion of known Pb-Zn districts. There are a few areas that have high potential but contain no known sediment hosted Pb-Zn occurrences, prospects, or deposits. In such areas, future investigations could be focused on better defining and constraining prospectivity with additional data.

The proliferation of induced seismicity in the Permian Basin, Texas

Released May 20, 2021 07:16 EST

2021, Journal of Geophysical Research (126)

Robert Skoumal, Daniel T. Trugman

The Permian Basin has a long history of induced earthquakes, but the seismicity rates have increased dramatically over the past two decades and included a MW 5.0 likely induced by wastewater disposal (WD) in March 2020. A detailed characterization of the proliferation of seismicity in the Permian Basin throughout this time period is needed for improving the scientific understanding of the mechanisms responsible and for mitigating future seismic hazard. Due to a sparse regional seismic network before the advent of Texas Seismological Network in 2017, we characterize seismicity using the 10-station TXAR array that is 100s of km away from most of the seismicity, with the objective of improving upon the substantial contributions from previous work. By exploiting the nature of waveform similarity, we detect events with template matching, performing a quantitative analysis of spatially varying detection capabilities throughout the study area. From an initial catalog of 10,753 events, we identify 45,009 earthquakes and 10,208 quarry blasts. Using our catalog of earthquakes, we improve epicentral locations, compare relative magnitude techniques, and associate earthquakes to WD or hydraulic stimulations. We further use our earthquake catalog to investigate the relationship between seismicity and human activities near the city of Pecos, Texas. Through a comparison of our earthquake catalog with industrial records, we determine that the vast majority seismicity near Pecos, Texas, since 2000 is likely induced by an increase of WD at wells injecting at depths greater than 1.5 km.

Atlantic sturgeon status and movement ecology in an extremely small spawning habitat: The Nanticoke River-Marshyhope Creek, Chesapeake Bay

Released May 20, 2021 07:14 EST

2021, Reviews in Fisheries Science and Aquaculture

D.H. Secor, M.H.P. O'Brien, N. Coleman, A. Horne, I. Park, David Kazyak, D. G. Bruce, C Stence

Biotelemetry of Atlantic sturgeon Acipenser oxyrinchus oxyrinchus has exposed spawning behaviors in ever-smaller estuaries, surprising for the NW Atlantic’s largest anadromous species. Small estuary — the Nanticoke River and Marshyhope Creek (Chesapeake Bay) — spawning-run adults and their habitat affinities are described based upon direct sampling and biotelemetry for the period 2014–2018. High rates of recapture over this period indicate a very small adult population size. Genetics revealed a very small effective population size (Ne = 12.2, 95% CI = 6.7–21.9). Most returns occurred during September at 20–27 °C. All fish departed as fall temperatures declined below 20 °C. Multi-beam sonar identified small-dispersed areas of sand-cobble and cobble, which could support adhesive embryo attachment. Movements of adults were higher during nighttime than daytime, with habitat preference for hard bottom habitats. Genetic evidence indicates that the sudden discovery of this population was unrelated to a hatchery release of several thousand juvenile sturgeon (Hudson River progeny) in 1997. The newly discovered population in the Nanticoke River exhibits a degree of resilience including multiple spawning regions and suitable spawning habitat. Still, critical vulnerabilities persist including curtailed habitat, continued agricultural and maritime development, invasive blue catfish, and a very small apparent population size.

Science needs of southeastern grassland species of conservation concern: A framework for species status assessments

Released May 20, 2021 07:06 EST

2021, Open-File Report 2021-1047

Reed F. Noss, Jennifer M. Cartwright, Dwayne Estes, Theo Witsell, K. Gregg Elliott, Daniel S. Adams, Matthew A. Albrecht, Ryan Boyles, Patrick J. Comer, Chris Doffitt, Don Faber-Langdoen, JoVonn G. Hill, William C. Hunter, Wesley M. Knapp, Mike Marshall, Milo Pyne, Jason R. Singhurst, Christopher Tracey, Jeffrey L. Walck, Alan Weakley

The unglaciated southeastern United States is a biodiversity hotspot, with a disproportionate amount of this biodiversity concentrated in grasslands. Like most hotspots, the Southeast is also threatened by human activities, with the total reduction of southeastern grasslands estimated as 90 percent (upwards to 100 percent for some types) and with many threats escalating today. This report summarizes the results of a multistakeholder workshop organized by the Southeastern Grasslands Initiative and the U.S. Geological Survey, held in January 2020 to provide a scientific needs assessment to help inform the Species Status Assessment (SSA) process under the U.S. Endangered Species Act, with a focus on grassland species and communities of conservation concern in the southeastern United States. This report reviews the ecology of southeastern grasslands, including influences on their origin, maintenance, and high species richness and endemism; presents findings from the workshop; and discusses science questions, hypotheses, and possibilities for future research projects to help fill key knowledge gaps.

Participants in the January 2020 workshop, representing diverse expertise in various topics in southeastern grassland ecology, were tasked with identifying major threats to grassland species in the Southeast as well as potential ways to make the SSA process more efficient and effective. An underlying assumption and starting place for workshop discussion was that an ecosystem-based approach to the SSA process is more cost-efficient than a species-by-species approach, in large part because many species with similar biological requirements can be addressed by the same actions. Nevertheless, one partner in this effort, the U.S. Fish and Wildlife Service, does require specific attention be given to taxa that have been petitioned for Federal listing, though as often as possible these taxa are considered alongside a larger group of priority taxa with an ecosystem approach.

For group discussions, workshop participants followed a modified “World Café” method, a structured conversational approach for knowledge sharing. Group discussions focused on five categories of threats to grassland communities and species: (1) habitat loss, fragmentation, and disruption of functional population connectivity; (2) climate change, especially changes in temperature and precipitation, including intensity and seasonality, and impacts on soil moisture, groundwater levels, and other ecosystem parameters; (3) changes to disturbance regimes, as influenced by climate and land-use change, extinctions, and human attitudes and behaviors; (4) invasive species (not limited to nonnative species); and (5) localized or subregional impacts such as sea-level rise. In addition to group discussions, workshop participants—as well as other grassland experts who were unable to attend the workshop—completed a preworkshop survey concerning challenges and opportunities for grassland conservation. Findings reported here under each of these topics represent ideas, problems, hypotheses, and questions identified by a diverse community of grassland managers and researchers which may be addressed by future research and monitoring in southeastern grassland ecosystems to help guide science-based conservation of grassland-dependent species.

Summary of oceanographic and water-quality measurements offshore of Matanzas Inlet, Florida, 2018

Released May 19, 2021 13:30 EST

2021, Open-File Report 2021-1014

Marinna A. Martini, Ellyn Montgomery, Steven E. Suttles, John C. Warner

U.S. Geological Survey (USGS) scientists and technical staff deployed instrumented underwater platforms and buoys to collect oceanographic and atmospheric data at two sites near Matanzas Inlet, Florida, on January 24, 2018, and recovered them on April 13, 2018. Matanzas Inlet is a natural, unmaintained inlet on the Florida Atlantic coast that is well suited to study inlet and cross-shore processes. The two study sites were located offshore of the surf zone, in 9 and 15 meters of water depth, in a line perpendicular to the coast. A sea-floor platform was deployed at each site to measure ocean currents, wave motions, acoustic and optical backscatter, temperature, salinity, and pressure. The objective was to quantify the hydrodynamic forcing for sediment transport and the response to such forcing near the seabed in the vicinity of an unmaintained inlet.

Characterization of factors affecting groundwater levels in and near the former Lake Traverse Indian Reservation, South Dakota, water years 1956–2017

Released May 19, 2021 09:12 EST

2021, Scientific Investigations Report 2020-5151

Kristen J. Valseth, Daniel G. Driscoll

The U.S. Geological Survey (USGS), in cooperation with the Sisseton Wahpeton Oyate, completed a study to characterize water-level fluctuations in observation wells relative to driving factors that affect water levels in and near the historical 1867 boundary of the Lake Traverse Indian Reservation. The study investigated concerns regarding potential effects of groundwater withdrawals and climate conditions on groundwater levels within an area that includes the historical boundary of the reservation and a surrounding area that extends 10 miles in all directions within South Dakota. Characterization of water-level fluctuations in observation wells and relative driving factors was accomplished by statistical trend analysis.

Monthly data from the Parameter-elevation Regressions on Independent Slopes Model (PRISM) were aggregated to obtain annual and seasonal datasets for total precipitation, minimum air temperature (Tmin), and maximum air temperature (Tmax) for the study area and a surrounding buffer area. Trend tests for gridded data for total precipitation, Tmin, and Tmax were completed for annual and seasonal time series for water years 1956–2017, which is about 2 years before the earliest available water-level measurements. A 2-year offset was arbitrarily selected because scrutiny of water-level and precipitation data indicated that responses of groundwater levels for many of the observation wells lagged major changes in precipitation patterns by about 2 years. Statistically significant upward trends were detected for annual precipitation and annual Tmin for most of the study area and the surrounding buffer area. Statistically significant downward trends in Tmax were detected for only a few 2.5 arc-minute grid cells; however, the sparsity of the spatial coverage reduces confidence that these are true trends, in contrast to the near completeness of the spatial coverage in upward trends for Tmin. Spatial distributions of statistically significant trends in seasonal climate data were generally similar to the annual trends, but with substantial differences in the spatial density of the trends.

Potential interactions among water levels in observation wells and streamflow were examined through correlation analyses of the annual median water level for each of 76 observation wells versus the annual mean streamflow for each of four area streamgages. Potential interactions among water levels in observation wells and lake levels were examined through correlation analyses involving 25 area lakes. Resulting correlation coefficients were used as part of an approach for selecting a lake to be plotted in conjunction with water-level and precipitation data for each observation well.

Groundwater trends for 76 observation wells were analyzed for three separate water-level parameters (minimum, median, and maximum) because wells are measured sporadically, and data are biased towards more frequent measurements during periods of heaviest irrigation demand. Trends in the time series of annual precipitation (from PRISM) starting 2 years earlier than the associated water-level trend also were analyzed for the location of each individual observation well. Sen’s slope and Mann-Kendall p-values were computed for the three water-level parameters and for the annual precipitation time series. Graphs showing results of trend analyses for each observation well also showed changes with time in the sum of licensed groundwater withdrawals within six specified radii (0.5, 1.0, 2.0, 3.0, 4.0, and 5.0 miles) of each well as a qualitative indicator of proximal groundwater demand.

Trends in groundwater levels in observation wells in the study area are predominantly upward, with 43 of 76 wells having significant upward trends for at least one of the three water-level parameters and only 8 wells having significant downward trends for at least one water-level parameter. The upward groundwater trends are driven by predominantly upward precipitation trends, with 43 wells (not all the same wells) also having significant upward trends and no wells having significant downward trends. Significant upward precipitation trends were detected for only two of the eight wells with significant downward groundwater trends. Groundwater levels in some observation wells likely are also substantially affected by interactions with surface water, especially with lakes. Water levels in many area lakes increased in response to wet conditions of the early 1990s and have maintained high water levels ever since. It is recognized that in many cases lakes that were selected for plotting with groundwater hydrographs likely are not hydraulically connected with a groundwater system or aquifer associated with an individual well; however, interactions also are plausible for numerous other lakes for which water-level records are not available.

Prototyping a methodology for long-term (1680-2100) historical-to-future landscape modeling for the conterminous United States

Released May 19, 2021 08:12 EST

2021, Land (10)

Jordan Dornbierer, Steve Wika, Charles Robison, Gregory Rouze, Terry L. Sohl

Land system change has been identified as one of four major Earth system processes where change has passed a destabilizing threshold. A historical record of landscape change is required to understand the impacts change has had on human and natural systems, while scenarios of future landscape change are required to facilitate planning and mitigation efforts. A methodology for modeling long-term historical and future landscape change was applied in the Delaware River Basin of the United States. A parcel-based modeling framework was used to reconstruct historical landscapes back to 1680, parameterized with a variety of spatial and nonspatial historical datasets. Similarly, scenarios of future landscape change were modeled for multiple scenarios out to 2100. Results demonstrate the ability to represent historical land cover proportions and general patterns at broad spatial scales and model multiple potential future landscape trajectories. The resulting land cover collection provides consistent data from 1680 through 2100, at a 30-m spatial resolution, 10-year intervals, and high thematic resolution. The data are consistent with the spatial and thematic characteristics of widely used national-scale land cover datasets, facilitating use within existing land management and research workflows. The methodology demonstrated in the Delaware River Basin is extensible and scalable, with potential applications at national scales for the United States.

Combining genetic and demographic monitoring better informs conservation of an endangered urban snake

Released May 19, 2021 08:10 EST

202, PLoS ONE (15)

Dustin A. Wood, Jonathan P. Rose, Brian J. Halstead, Ricka E. Stoelting, Karen E Swaim, A. G. Vandergast

Conversion and fragmentation of wildlife habitat often leads to smaller and isolated populations and can reduce a species’ ability to disperse across the landscape. As a consequence, genetic drift can quickly lower genetic variation and increase vulnerability to extirpation. For species of conservation concern, quantification of population size and connectivity can clarify the influence of genetic drift in local populations and provides important information for conservation management and recovery strategies. Here, we used genome-wide single nucleotide polymorphism (SNP) data and capture-mark-recapture methods to evaluate the genetic diversity and demography within seven focal sites of the endangered San Francisco gartersnake (Thamnophis sirtalis tetrataenia), a species affected by alteration and isolation of wetland habitats throughout its distribution. The primary goals were to determine the population structure and degree of genetic isolation among T. s. tetrataenia populations and estimate effective size and population abundance within sites to better understand the present and future importance of genetic drift. We also used temporally sampled datasets to examine the magnitude of genetic change over time. We found moderate population genetic structure throughout the San Francisco Peninsula that partitions sites into northern and southern regional clusters. Point estimates of both effective size and population abundance were generally small (≤ 100) for a majority of the sites, and estimates were particularly low in the northern populations. Genetic analyses of temporal datasets indicated an increase in genetic differentiation, especially for the most geographically isolated sites, and decreased genetic diversity over time in at least one site (Pacifica). Our results suggest that drift-mediated processes as a function of small population size and reduced connectivity from neighboring populations may decrease diversity and increase differentiation. Improving genetic diversity and connectivity among T. s. tetrataenia populations could promote persistence of this endangered snake.

Incorporating climate change in a harvest risk assessment for polar bears Ursus maritimus in Southern Hudson Bay

Released May 19, 2021 07:26 EST

2021, Biological Conservation (258)

Eric V. Regehr, Markus Dyck, Samuel A. Iverson, David S. Lee, Nicholas J Lunn, Joseph M Northrup, Marie-Claude Richer, Guillaume Szor, Michael C. Runge

Arctic marine mammals are harvested by Indigenous people for subsistence and are socially and culturally important. For ice-dependent species like the polar bear Ursus maritimus, management and conservation require understanding interactions between harvest and sea-ice loss due to climate change. We developed a demographic model to evaluate harvest risk for polar bears in Southern Hudson Bay, Canada, where the annual ice-free season has increased by approximately one month in recent decades. The model was based on the theta-logistic equation and allowed for density-dependent changes (through carrying capacity [K]) and density-independent changes (through population growth rate [r]). Model parameters were estimated using a Bayesian Monte Carlo method that included capture-recapture, aerial survey, and harvest data. Harvest management followed a state-dependent approach under which new estimates of abundance were used to update the harvest level every five years. Under a middle-of-the-road environmental scenario that assumed K and r would decline in proportion to projected sea-ice declines, annual removal of 0.02–0.03 of females resulted in a 0.8 probability of maintaining subpopulation abundance above maximum net productivity level for three polar bear generations (~34 years), our primary criterion for sustainability. Under more pessimistic and optimistic environmental scenarios, comparable female harvest rates were 0.01 and 0.055, respectively. Our coupled modeling-management framework can be used to inform tradeoffs between protection and sustainable use for wildlife populations experiencing habitat loss.

The 2008-2010 subsidence of Dallol volcano on the 2 spreading Erta Ale ridge: InSAR observations and source models

Released May 19, 2021 07:14 EST

2021, Remote Sensing (13)

Maurizio Battaglia, Carolina Paglia, Stefano Meuti

In this work, we study the subsidence of Dallol, an explosive crater and hydrothermal area along the spreading Erta Ale ridge of Afar (Ethiopia). No volcanic products exist at the surface. However, a diking episode in 2004, accompanied by dike-induced faulting, indicates that Dallol is an active volcanic area. The 2004 diking episode was followed by quiescence until subsidence started in 2008. We use InSAR to measure the deformation, and inverse, thermoelastic and poroelastic modelling to understand the possible causes of the subsidence. Analysis of InSAR data from 2004–2010 shows that subsidence, centered at Dallol, initiated in October 2008, and continued at least until February 2010 at an approximately regular rate of up to 10 cm/year. The inversion of InSAR average velocities finds that the source causing the subsidence is shallow (depth between 0.5 and 1.5 km), located under Dallol and with a volume decrease between −0.63 and −0.26 × 106 km3/year. The most likely explanation for the subsidence of Dallol volcano is a combination of outgassing (depressurization), cooling and contraction of the roof of a shallow crustal magma chamber or of the hydrothermal system.

Flood of June 30–July 1, 2018, in the Fourmile Creek Basin, near Ankeny, Iowa

Released May 19, 2021 07:08 EST

2021, Open-File Report 2021-1044

Padraic S. O'Shea, Jared C. Vegrzyn, Kimberlee K. Barnes

Major flooding occurred June 30–July 1, 2018, in the Fourmile Creek Basin in central Iowa after thunderstorm activity over the region. The largest recorded 24-hour precipitation total at a National Oceanic and Atmospheric Administration weather station was 8.72 inches in Ankeny, Iowa, and 7.54 inches in Des Moines, Iowa. A maximum peak-of-record discharge of 10,000 cubic feet per second was recorded at U.S. Geological Survey streamgage 05485605, Fourmile Creek near Ankeny, Iowa, on July 1, 2018, with an annual exceedance probability of less than 0.2 percent. A maximum peak-of-record discharge of 12,000 cubic feet per second also was recorded at U.S. Geological Survey streamgage 05485640, Fourmile Creek at Des Moines, Iowa, on July 1, 2018, with an annual exceedance-probability range of 0.5–1 percent. High-water mark elevations were surveyed at 11 locations along Fourmile Creek between State Highway 163 in Pleasant Hill, Iowa, and U.S. Route 69 near Alleman, Iowa, a distance of 21.0 river miles. The high-water marks were used to develop a flood profile for Fourmile Creek.

Forest evapotranspiration dynamics over a fragmented forest landscape under drought in southwestern Amazonia

Released May 19, 2021 06:45 EST

2021, Agricultural and Forest Meteorology (306)

Izaya Numata, Kul Bikram Khand, Jeppe Kjaersgaard, Mark A. Cochrane, Sonaira S. Silva

Ongoing climate change and human conversion of forests to other land uses alter regional evapotranspiration dynamics and, consequently, impact associated hydrological systems in Amazonia. We studied the effects of drought and fragmentation on forest evapotranspiration using the surface energy balance-based model METRIC (Mapping Evapotranspiration at high Resolution with Internalized Calibration) for a fragmented forest landscape in Brazil's Amazonian state of Rondônia.

Dry season (June-August) forest evapotranspiration estimates were produced for the 2009-2011 period that encompassed the 2010 drought event, one of the extreme droughts in the Amazon. METRIC evapotranspiration data were analyzed in relation to climate (monthly precipitation and cumulative water deficit) and forest fragmentation (edge distance from 100m to 1000m from forest edge and edge density). During the dry season of 2009, pre-drought, forest evapotranspiration did not fall below 110mm/month. However, the 2010 drought year showed a drastic decline in evapotranspiration by 32%, to 75mm/month, from July to August. In 2011, evapotranspiration rates were still depressed with August rates dropping as low as 85mm/month. Forest evapotranspiration dynamics were driven mainly by precipitation and corresponding water deficits in the drier years (2010 and 2011), although evapotranspiration deficits along the edges of forest fragments were locally significant, at the landscape scale. The forests near edges (to 100m) had progressively lower evapotranspiration levels than interior forests as dry seasons progressed and these differences were greatest in the 2010 drought year, reaching almost 5%.

Our results suggest that during the driest months, fragmentation exacerbated both the rate and extent of evapotranspiration reductions over forest areas up to 100m from edges, equivalent to ~20% of the forested landscape in our study area.

Dissolved Fe supply to the central Gulf of Alaska is inferred to be derived from Alaskan glacial dust that is not resolved by dust transport models

Released May 19, 2021 06:41 EST

2021, JGR-Biogeosciences

John Crusius

Re-examination of previously published dissolved iron time-series data from Ocean Station Papa in the central Gulf of Alaska (GoA) reveals 33-70% increases in the dissolved iron inventories occurring between September and February of successive years, implying a source of Fe to this region during autumn or early winter. Because I can virtually rule out many possible iron sources at this time of year, I suggest Alaskan glacial dust is the likely iron source. Large plumes of such dust are known to be generated regularly in the autumn by anomalous offshore winds and channelled through mountain gaps, simultaneously from several locations spanning ∼1000 km of the northern Gulf of Alaska coastline. Large dust flux events occur when below-freezing, low-humidity air temperatures persist for many days during the autumn. I suggest that existing state-of-the-art global dust models fail to reproduce this Alaskan dust flux because the model spatial resolution is too coarse to resolve the high winds through the narrow mountain gaps that generate the dust. Future work that could help to confirm this Fe source to the central GoA includes time-series profiles of iron concentrations, and ancillary information from sensor-equipped profiling floats. If this mechanism of Fe supply to the central GoA were confirmed, it would imply this Alaskan dust is transported ≥ 1100 km from the coast, more than twice as far as has been visually documented from satellite observations.

Dynamics of endangered sucker populations in Clear Lake Reservoir, California

Released May 18, 2021 16:18 EST

2021, Open-File Report 2021-1043

David A. Hewitt, Brian S. Hayes, Alta C. Harris, Eric C. Janney, Caylen M. Kelsey, Russell W. Perry, Summer M. Burdick

Executive Summary

In collaboration with the Bureau of Reclamation, the U.S. Geological Survey began a consistent monitoring program for endangered Lost River suckers (Deltistes luxatus) and shortnose suckers (Chasmistes brevirostris) in Clear Lake Reservoir, California, in fall 2004. The program was intended to improve understanding of the Clear Lake Reservoir populations because they are important to recovery efforts for these species. We report results from the ongoing program and include sampling efforts through fall 2019. We summarize catches and passive integrated transponder (PIT) tagging efforts from trammel net sampling in the fall seasons (September–October each year) and detections of PIT-tagged suckers on remote antennas in the spring in each year from 2006 to 2019. We also combine the data from physical captures and remote detections in capture-recapture models to provide estimates of annual survival for suckers in the reservoir.

A lack of genetic distinctiveness between shortnose suckers and Klamath largescale suckers (Catostomus snyderi) in the Lost River subbasin, including Clear Lake Reservoir, is a likely cause of past difficulty in identification of these species. Field identification can be subjective for many captured individuals, and very few individuals were identified as Klamath largescale suckers in the most recent years of our monitoring program. For this report, we combine individuals that were identified as either shortnose sucker (SNS) or Klamath largescale sucker (KLS) into a single “SNS-KLS” group for most analyses. Identification of Lost River suckers (LRS) is based on external morphological characteristics.

Sediment characteristics of northwestern Wisconsin’s Nemadji River, 1973–2016

Released May 18, 2021 16:16 EST

2021, Open-File Report 2021-1003

Faith A. Fitzpatrick

In 2015–16, a comparison study of stream sediment collection techniques was done for a U.S. Geological Survey streamgage on the Nemadji River near South Superior, Wisconsin (U.S. Geological Survey station number 04024430) to provide an adjustment factor for comparing suspended-sediment rating curves for two historical periods 1973–86 and 2006–16. During 1973–1986, the U.S. Geological Survey used the equal-width-increment technique to collect suspended-sediment concentration data (EWI SSC). The Wisconsin Department of Natural Resources and Minnesota Pollution Control Agency collected grab samples for total suspended solids (grab TSS) concentration starting in 2006 and continuing beyond 2016. In addition to the comparison study of suspended-sediment concentrations, bedload and bed material samples were collected in 2015–16, and the modified Einstein procedure was run to further characterize total sediment loads. The 2015–16 study indicated that the EWI SSC and grab TSS concentrations were different, but not as much as expected, especially on the high end where grab TSS concentrations were sometimes higher than EWI SSC concentrations, possibly due to a combination of a high percentage of fines in suspension and higher concentrations in the center of the channel than the margins. The 2015–16 measured bedload made up a small percentage of total sediment load, and bedload and streambed particle sizes are 90 to 100 percent sand sized or smaller. The relative proportion of measured bedload to total load decreased with increased streamflow, and for streamflows greater than 1,800 cubic feet per second, the suspended load made up 98 percent of the total load. Calculated 2015–16 instantaneous total sediment loads from the modified Einstein procedure were up to 70 percent of the measured loads for flows less than 1,000 cubic feet per second and near or more than 100 percent for flows greater than 1,000 cubic feet per second. The sediment rating curve developed for the 2006–16 adjusted grab TSS data had a similar slope but a lower intercept than its 1973–86 EWI SSC counterpart, indicating that for a given streamflow, suspended-sediment concentrations were lower for 2006–16 compared to 1973–86. The negative offset equates to estimates of annual suspended-sediment loads in 2006–16 being on average 87 percent of the 1973–86 loads. Over the period 2009–16, annual suspended-sediment loads ranged from a low of about 21,000 tons per year in 2015 to a high of 167,000 tons per year in 2012 with a mean of 85,000 tons per year. However, reductions in suspended-sediment concentrations are likely obscured by large loads during years with flooding.

Investigation of otolith microstructure and composition for identification of rearing strategies and associated Baker Lake sockeye salmon (Oncorhynchus nerka) smolt production, Washington, 2016–17

Released May 18, 2021 15:49 EST

2021, Open-File Report 2021-1032

Kimberly A. Larsen, Lisa A. Wetzel, Karl D. Stenberg, Angie M. Lind-Null

Baker River (Washington, USA) sockeye salmon (Oncorhynchus nerka) are a recovering Puget Sound stock that are aided by trap-and-haul and hatchery programs to mitigate for the presence of a high head dam. The relative contribution of hatchery and natural adults to overall production of smolts and recruits is unknown. The ability to identify three different sockeye production groups (natural production, artificial incubation, and artificial spawning beach) within the Baker system is crucial to moving forward with management goals. The examination of otoliths was proposed as a technical tool for improved understanding and management of Baker sockeye rebuilding efforts. Otoliths were chosen as they provide a chronological record on an individual fish basis and have been shown to identify fish origin through both otolith microstructure and chemistry.

The goal of this pilot project was to determine the feasibility of assigning sockeye to their production source based on otolith analysis. A variety of methods were employed and compared for accuracy of group assignment. The maximum overall accuracy capable of attainment was 88.57 percent, however complete confidence (100 percent) in the separation of natural production from artificial production was reached through the analysis of trace elements alone. Some segregation of the two artificial production groups was reached through analysis of a few specific trace elements (magnesium, manganese, and zinc). This confidence in assignment for the artificial production groups was aided by a two-step process of combining trace elements with microstructure. The Sr isotope ratios supported the trace element findings but did not help to boost the overall level of confidence in the separation of production groups. Based upon the results from this preliminary investigation, one could choose a statistically sound, efficient, and cost-effective use of otoliths as a tool for discriminating between the sockeye production groups of the Baker Lake system.

A socio-ecological imperative for broadening participation in coastal and estuarine research and management

Released May 18, 2021 07:25 EST

2021, Estuaries and Coasts

Lora A. Harris, Treda Grayson, Hilary A. Neckles, Christopher T Emrich, Kristy A Lewis, Kristin W. Grimes, Shanna Williamson, Corey Garza, Christine R Whitcraft, Jennifer Beseres Pollack, Drew M Talley, Benjamin Fertig, Cindy M Palinkas, Susan Park, Jamie MP Vaudrey, Allison M Fitzgerald, Johnny Quispe

For most of the scientific disciplines associated with coastal and estuarine research, workforce representation does not match the demographics of communities we serve, especially for Black, Hispanic or Latino, and Indigenous peoples. This essay provides an overview of this inequity and identifies how a scientific society can catalyze representational, structural, and interactional diversity to achieve greater inclusion. Needed changes go beyond representational diversity and require an intentional commitment to build capacity through inclusivity and community engagement by supporting anti-racist policies and actions. We want to realize a sense of belonging on the part of scientists in society at large and enable research pursuits through a lens of social justice in service of coastal communities. Minimally, this framework offers an avenue for increased recruitment of individuals from more diverse racial and ethnic identities. More broadly, the mechanisms described here aim to create a culture in scientific societies in which social justice, driven by anti-racist actions, produces systemic change in how members of scientific societies approach, discuss, and address issues of inequity. We have written this essay for members of the coastal and marine science community who are interested in change. We aim to call in new voices, allies, and champions to this work.

Pilot-scale expanded assessment of inorganic and organic tapwater exposures and predicted effects in Puerto Rico, USA

Released May 18, 2021 06:57 EST

2021, Environment International (788)

Paul Bradley, Ingrid Y. Padilla, Kristin Romanok, Kelly Smalling, Michael J. Focazio, Sara Breitmeyer, Mary C. Cardon, Justin M. Conley, Nicola Evans, Carrie E Givens, James L. Gray, L. Earl Gray, Phillip C. Hartig, Michelle Hladik, Christopher P. Higgins, Luke R. Iwanowicz, Rachael Lane, Keith Loftin, R. Blaine McCleskey, Carrie A. McDonough, Elizabeth Medlock-Kakaley, Shannon M. Meppelink, Christopher P. Weis, Vickie S. Wilson

A pilot-scale expanded target assessment of mixtures of inorganic and organic contaminants in point-of-consumption drinking water (tapwater, TW) was conducted in Puerto Rico (PR) to continue to inform TW exposures and corresponding estimations of cumulative human-health risks across the US. In August 2018, a spatial synoptic pilot assessment of than 524 organic, 37 inorganic, and select microbiological contaminant indicators was conducted in 14 locations (7 home; 7 commercial) across PR. A follow-up 3-day temporal assessment of TW variability was conducted in December 2018 at two of the synoptic locations (1 home, 1 commercial) and included daily pre- and post-flush samples. Concentrations of regulated and unregulated TW contaminants were used to calculate cumulative in vitro bioactivity ratios and Hazard Indices (HI) based on existing human-health benchmarks. Synoptic results confirmed that human exposures to inorganic and organic contaminant mixtures, which are rarely monitored together in drinking water at the point of consumption, occurred across PR and consisted of elevated concentrations of inorganic contaminants (e.g., lead, copper), disinfection byproducts (DBP), and to a lesser extent per/polyfluoroalkyl substances (PFAS) and phthalates. Exceedances of human-health benchmarks in every synoptic TW sample support further investigation of the potential cumulative risk to vulnerable populations in PR and emphasize the importance of continued broad characterization of drinking-water exposures at the tap with analytical capabilities that better represent the complexity of both inorganic and organic contaminant mixtures known to occur in ambient source waters. Such health-based monitoring data are essential to support public engagement in source water sustainability and treatment and to inform consumer point-of-use treatment decision making in PR and throughout the US.

Molluscan aminostratigraphy of the US Mid-Atlantic Quaternary coastal system: Implications for onshore-offshore correlation, paleochannel and barrier island evolution, and local late Quaternary sea-level history

Released May 18, 2021 06:48 EST

2021, Quaternary Geochronology

John Wehmiller, Laura L. Brothers, Kelvin Ramsey, David S. Foster, C.R. Mattheus, Christopher Hein, Justin L. Shawler

The Quaternary record of the US Mid-Atlantic coastal system includes onshore emergent late Pleistocene shoreline deposits, offshore inner shelf and barrier island units, and paleovalleys formed during multiple glacial stage sea-level lowstands. The geochronology of this coastal system is based on uranium series, radiocarbon, amino acid racemization (AAR), and optically stimulated luminescence (OSL) methods. We report over 600 mollusk AAR results from 93 sites between northeastern North Carolina and the central New Jersey shelf, representing samples from both onshore cores or outcrops, sub-barrier and offshore cores, and transported shells from barrier island beaches. AAR age estimates are constrained by paired 14C analyses on specific shells and associated U-series coral ages from onshore sites. AAR data from offshore cores are interpreted in the context of detailed seismic stratigraphy. The distribution of Pleistocene-age shells on the island beaches is linked to the distribution of inner shelf or sub-barrier source units. Age mixing over a range of time-scales (~1 ka to ~100 ka) is identified by AAR results from onshore, beach, and shelf collections, often contributing insights into the processes forming individual barrier islands. The regional aminostratigraphic framework identifies a widespread late Pleistocene (Marine Isotope Stage 5) aminozone, with isolated records of middle and early Pleistocene deposition. AAR results provide age estimates for the timing of formation of the three major paleochannels that underlie the Delmarva Peninsula: Persimmon Point paleochannel ≥800 ka; Exmore paleochannel ~400–500 ka (MIS 12); and Eastville paleochannel > 125 ka (MIS 6). The results demonstrate the value of synthesizing abundant AAR chronologic data across various coastal environments, integrating multiple distinct geologic studies. The ages and elevations of the Quaternary units are important for current hypotheses about relative sea-level history and crustal dynamics in the region, which was likely influenced by the Laurentide ice sheet, the margin just ~400 km to the north.

Northern Madtom use of artificial reefs in the St. Clair–Detroit River System

Released May 17, 2021 15:55 EST

2021, North American Journal of Fisheries Management

Jennifer Johnson, Justin A. Chiotti, Andrew S Briggs, James C. Boase, Jan-Michael Hessenauer, Edward F. Roseman

The St. Clair and Detroit rivers historically supported abundant fish populations. However, like many river systems, these rivers have been greatly altered through the creation of navigation channels and other anthropogenic disturbances, resulting in the loss of fish and wildlife habitat and declines in native fish populations. To ameliorate this environmental degradation, artificial fish spawning reefs were constructed in the St. Clair and Detroit rivers. One native species to potentially benefit from artificial reefs is the Northern Madtom Noturus stigmosus, a small ictalurid that is listed as endangered in the state of Michigan and the province of Ontario. Between 2016 and 2018, artificial reefs and nearby control sites were sampled in the St. Clair and Detroit rivers to compare the number of Northern Madtoms. In total, 171 Northern Madtoms were captured in 1,848 minnow traps with one of four bait types: cheese, dog food, worms, or control (no bait). Baited minnow traps successfully captured Northern Madtoms in the fast-flowing, deep water of the St. Clair–Detroit River system, and catch rates were significantly higher when traps were baited with worms. The number of Northern Madtoms captured was lower in the Detroit River than in the St. Clair River and increased with increasing water temperature and turbidity. Artificial reefs constructed in the St. Clair–Detroit River system are providing habitat for Northern Madtoms; however, use did not differ between reef sites and nearby control sites. This work provides insight regarding sampling strategies to target Northern Madtoms in large-river systems and highlights the importance of incorporating a temporal sampling strategy into survey design.

Aeolian sediments in paleowetland deposits of the Las Vegas Formation

Released May 17, 2021 08:21 EST

2021, Quaternary Research

Harland L. Goldstein, Kathleen B. Springer, Jeffrey S. Pigati, Marith C. Reheis, Gary L. Skipp

The Las Vegas Formation (LVF) is a well-characterized sequence of groundwater discharge (GWD) deposits exposed in and around the Las Vegas Valley in southern Nevada. Nearly monolithologic bedrock surrounds the valley, which provides an excellent opportunity to test the hypothesis that GWD deposits include an aeolian component. Mineralogical data indicate that the LVF sediments are dominated by carbonate minerals, similar to the local bedrock, but silicate minerals are also present. The median particle size is ~35 μm, consistent with modern dust in the region, and magnetic properties contrast strongly with local bedrock, implying an extralocal origin. By combining geochemical data from the LVF sediments and modern dust, we found that an average of ~25% of the LVF deposits were introduced by aeolian processes. The remainder consists primarily of authigenic groundwater carbonate as well as minor amounts of alluvial material and soil carbonate. Our data also show that the aeolian sediments accumulated in spring ecosystems in the Las Vegas Valley in a manner that was independent of both time and the specific hydrologic environment. These results have broad implications for investigations of GWD deposits located elsewhere in the southwestern U.S. and worldwide.

Coral reef resilience differs among islands within the Gulf of Mannar, southeast India, following successive coral bleaching events

Released May 17, 2021 08:13 EST

2021, Coral Reefs

K Diraviya Raj, Greta S. Aeby, G.M. Mathews, Gareth J Williams, Jamie M. Caldwell, R L Laju, M Selva Bharath, P Dinesh Kumar, A Arasamuthu, N Gladwin Gnana Asir, Lisa M. Wedding, Andrew Daview, Monica Mei Jeen Moritsch, J K Patterson Edward

We used a 12-yr data set of benthic cover (2005–2017), spanning two bleaching events, to assess changes in benthic cover and coral community composition along 21 islands within Gulf of Mannar (GoM), southeast India. Overall, between 2005 and 2017 reefs had a simultaneous decrease in relative coral cover (avg. =  − 36%) and increase in algal cover (avg. =  + 45%). Changes in benthic cover were not consistent among islands, ranging from − 34 to + 5% for coral cover and from − 0.3 to + 50% for algae. There was a spatial gradient in coral mortality, which increased among islands from west to east. However, there was a disconnect between coral loss and subsequent increases in algae. Algal cover increased more on islands in west GoM where coral loss was minimal. Environmental co-factors (coral cover, percent bleaching, degree heating weeks, fish densities, Chl-a, pollution) explained > 50% of the benthic cover responses to successive bleaching. Coral survival was favored on islands with higher fish densities and chlorophyll-a levels, and increases in algal cover were associated with higher measures of pollution from terrestrial runoff. Coral morphotypes differed in their response following successive bleaching resulting in changes in the relative abundance of different coral morphotypes. Existing climate projections (RCP8.5) indicate a 22-yr gap in the onset of annual severe bleaching (ASB) for reefs in the east versus west GoM, and ASB was ameliorated for all reefs under the RCP4.5 projections. There is limited knowledge of the resilience of GoM reefs, and this study identifies coral morphotypes and reefs that are most likely to recover or decline from successive bleaching, in the context of forecasts of the frequency of future bleaching events in GoM.

Quantifying slopes as a driver of forest to marsh conversion using geospatial techniques: Application to Chesapeake Bay coastal-plain, USA

Released May 17, 2021 07:49 EST

2021, Frontiers in Environmental Science (9)

Grace Damore Molino, Zafer Defne, Alfredo Aretxabaleta, Neil Kamal Ganju, Joel A. Carr

Coastal salt marshes, which provide valuable ecosystem services such as flood mitigation and carbon sequestration, are threatened by rising sea level. In response, these ecosystems migrate landward, converting available upland into salt marsh. In the coastal-plain surrounding Chesapeake Bay, United States, conversion of coastal forest to salt marsh is well-documented and may offset salt marsh loss due to sea level rise, sediment deficits, and wave erosion. Land slope at the marsh-forest boundary is an important factor determining migration likelihood, however, the standard method of using field measurements to assess slope across the marsh-forest boundary is impractical on the scale of an estuary. Therefore, we developed a general slope quantification method that uses high resolution elevation data and a repurposed shoreline analysis tool to determine slope along the marsh-forest boundary for the entire Chesapeake Bay coastal-plain and find that less than 3% of transects have a slope value less than 1%; these low slope environments offer more favorable conditions for forest to marsh conversion. Then, we combine the bay-wide slope and elevation data with inundation modeling from Hurricane Isabel to determine likelihood of coastal forest conversion to salt marsh. This method can be applied to local and estuary-scale research to support management decisions regarding which upland forested areas are more critical to preserve as available space for marsh migration.

Monitoring long-term riparian vegetation trends to inform local habitat management in a mountainous environment

Released May 17, 2021 07:22 EST

2021, Ecological Indicators (127)

Timothy J. Assal, Valerie A. Steen, Todd Caltrider, Travis Cundy, Cheyenne Stewart, Nicholas Manning, Patrick J. Anderson

Riparian ecosystems provide critical habitat for many species, yet assessment of vegetation condition at local scales is difficult to measure when considering large areas over long time periods. We present a framework to map and monitor two deciduous cover types, upland and riparian, occupying a small fraction of an expansive, mountainous landscape in north-central Wyoming. Initially, we developed broad-scale predictions of predominant woody vegetation types by integrating Landsat data into species distribution models and combining subsequent outputs into a synthesis map. Then, we evaluated a 35-year Landsat time series (1985–2019) using the Mann-Kendall test to identify significant trends in the condition of upland and riparian deciduous vegetation and assessed the rate and direction of change using the Theil-Sen estimator. Finally, we used plot level data to assess the utility of the framework to detect bottom-up controls (ungulate browse pressure and management actions) on vegetation condition. The synthesis map had an overall correct classification rate of 87% and field data indicated deciduous vegetation within 45 m of coniferous forest faces increased pressure of conifer expansion. The trend assessment identified consistent patterns operating at the landscape scale across both upland and riparian deciduous vegetation; a predominant greening trend was observed for 12 years followed by a 9-year browning trend, before switching back to a greening trend for the last 13 years of the study. Our results indicate trends are driven by the climate of the measurement period at the landscape scale. Although we did not find conclusive evidence to establish a strong link between browse pressure and satellite data, we highlight examples where prevailing trends can be overridden by local disturbance or management intervention. This framework is transferable to other understudied riparian environments throughout western North America to provide insight on ecohydrological processes and assess global and local stressors across broad spatiotemporal scales.

The importance of wilderness to wolf (Canis lupus) survival and cause-specific mortality over 50 years

Released May 17, 2021 07:17 EST

2021, Biological Conservation (258)

Shannon Barber-Meyer, Tyler Wheeldon, L. David Mech

We assessed the relative importance of wilderness to gray wolf (Canis lupus) population dynamics over 50 years in a population that 1) was long extant (i.e., not reintroduced or recolonized), 2) was not subject to harvest in our study area until recently, and 3) used both wilderness and adjacent, mainly public, non-wilderness. We analyzed the survival of radiocollared wolves (n = 756 collared-wolf tenures) during 1968–2018 in the Superior National Forest, Minnesota, USA, including the Boundary Waters Canoe Area Wilderness. Over 50 years, adult annual survival was 78%. Wolves captured in wilderness tended to exhibit higher survival than those captured in nonwilderness, but the difference was more pronounced during harvest years and post-harvest years when wilderness wolf survival remained relatively high and non-wilderness wolf survival dropped (relative to pre-harvest). During Nov–Apr of pre-harvest years for adults, the natural mortality rate was similar for non-wilderness wolves and wilderness wolves (both 6%), but the anthropogenic mortality rate was higher for non-wilderness wolves than wilderness wolves (7% versus 1%), as was the illegal mortality rate (5% versus 1%). During Nov–Apr of preharvest years, wilderness wolves were less likely to die than non-wilderness wolves (p = 0.042; hazard ratio = 0.59), pups were more likely to die than adults (p = 0.002; hazard ratio = 1.84), and males were less likely to die than females (p = 0.053; hazard ratio = 0.73). Our long-term wolf survival, cause-specific mortality, and hazard results will inform management agencies whenever wolves are delisted, and jurisdiction for them passes to states.

Recovering individual-level spatial inference from aggregated binary data

Released May 17, 2021 06:56 EST

2021, Spatial Statistics (44)

Nelson Walker, Trevor J. Hefley, Anne Ballmann, Robin E. Russell, Daniel P. Walsh

Binary regression models are commonly used in disciplines such as epidemiology and ecology to determine how spatial covariates influence individuals. In many studies, binary data are shared in a spatially aggregated form to protect privacy. For example, rather than reporting the location and result for each individual that was tested for a disease, researchers may report that a disease was detected or not detected within geopolitical units. Often, the spatial aggregation process obscures the values of response variables, spatial covariates, and locations of each individual, which makes recovering individual-level inference difficult. We show that applying a series of transformations, including a change of support, to a bivariate point process model allows researchers to recover individual-level inference for spatial covariates from spatially aggregated binary data. The series of transformations preserves the convenient interpretation of desirable binary regression models that are commonly applied to individual-level data. Using a simulation experiment, we compare the performance of our proposed method under varying types of spatial aggregation against the performance of standard approaches using the original individual-level data. We illustrate our method by modeling individual-level probability of infection using a data set that has been aggregated to protect an at-risk and endangered species of bats. Our simulation experiment and data illustration demonstrate the utility of the proposed method when access to original non-aggregated data is impractical or prohibited.

Oxygen isotopes in terrestrial gastropod shells track Quaternary climate change in the American Southwest

Released May 17, 2021 06:49 EST

2021, Quaternary Research

Jason A. Rech, Jeffrey S. Pigati, Kathleen B. Springer, Stephanie Bosch, Jeffrey C. Nekola, Yurena Yanes

Recent studies have shown the oxygen isotopic composition (δ18O) of modern terrestrial gastropod shells is determined largely by the δ18O of precipitation. This implies that fossil shells could be used to reconstruct the δ18O of paleo-precipitation as long as the isotopic system, including the hydrologic pathways of the local watershed and the gastropod systematics, is well understood. In this study, we measured the δ18O values of 456 individual gastropod shells collected from paleowetland deposits in the San Pedro Valley, Arizona that range in age from ca. 29.1 to 9.8 ka. Isotopic differences of up to 2‰ were identified among the four taxa analyzed (Succineidae, Pupilla hebesGastrocopta tappaniana, and Vallonia gracilicosta), with Succineidae shells yielding the highest values and Vgracilicosta shells exhibiting the lowest values. We used these data to construct a composite isotopic record that incorporates these taxonomic offsets, and found shell δ18O values increased by ~4‰ between the last glacial maximum and early Holocene, which is similar to the magnitude, direction, and rate of isotopic change recorded by speleothems in the region. These results suggest the terrestrial gastropods analyzed here may be used as a proxy for past climate in a manner that is complementary to speleothems, but potentially with much greater spatial coverage.

Research to inform Caltrans best management practices for reptile and amphibian road crossings

Released May 15, 2021 08:55 EST

2021, Report

Cheryl S. Brehme, R. N. Fisher, Tom E. S. Langton, Anthony P. Clevenger, Esther Adelsheim, Stephanie Barnes, Tristan Edgarian, Brittany Ewing, Stacie A. Hathaway, Michael Hobbs, Jennifer Kingston, A. Launer, Tritia A. Matsuda, Jeremy B. Sebes, C. Vaughn, Elise Watson

In October of 2014, the U.S. Geological Survey (USGS) began a 5-year project to conduct research to inform Best Management Practices (BMPs) for amphibian and reptile crossing and barrier systems in California. To inform future conservation and transportation planning, this project involved identification of species at highest risk of negative road impacts, creation of geodatabase and spatial mapping tools that crosswalk with California Essential Habitat Connectivity Planning, and field research to address information gaps in the efficacy of reptile and amphibian passage and barrier systems. Per the agreement with California Department of Transportation (Caltrans; agreement 65A0553), this project was part of a broader collaborative effort between the Western Transportation Institute (WTI) of Montana State University and USGS Western Ecological Research Center (WERC). As part of this broader project, WTI conducted a worldwide literature review and gap analysis and produced the BMP manual for herpetofauna in California. WTI and USGS were contracted separately although we worked closely together throughout this broader effort and each brought particular expertise to the project. WTI has expertise in highways, the attributes of the highway environment, and has broad international experience with road ecology and herpetofauna connectivity systems worldwide. USGS WERC has expertise with California amphibian and reptile species and their ecology, study design and implementation, as well as expertise in landscape connectivity and road ecology.

Modeling of future COVID-19 cases, hospitalizations, and deaths, by vaccination rates and nonpharmaceutical intervention scenarios — United States, April–September 2021

Released May 14, 2021 11:54 EST

2021, Morbidity and Mortality Weekly Report (70) 719-724

Rebecca K. Borchering, Cecile Viboud, Emily Howerton, Claire P. Smith, Shaun Truelove, Michael C. Runge, Nicholas G. Reich, Lucie Contamin, John Levander, Jessica Salerno, Wilbert van Panhuis, Matt Kinsey, Kate Tallaksen, R. Freddy Obrecht, Laura Asher, Cash Costello, Michael Kelbaugh, Shelby Wilson, Lauren Shin, Molly Gallagher, Luke Mullany, Kaitlin Rainwater-Lovett, Joseph Lemaitre, Juan Dent, Kyra Grantz, Joshua Kaminsky, Stephen Lauer, Elizabeth Lee, Hannah Meredith, Javier Perez-Saez, Lindsay T. Keegan, Dean Karlen, Matteo Chinazzi, Jessica Davis, Kunpeng Mu, Xinyue Xiong, Ana Pastore y Piontti, Alessandro Vespignani, Ajitesh Srivastava, Przemyslaw Porebski, Srinivasan Venkatramanan, Aniruddha Adiga, Bryan Lewis, Brian Klahn, Joseph Outten, James Schlitt, Patrick Corbett, Pyrros A. Telionis, Lijing Wang, Akhil S. Peddireddy, Benjamin Hurt, Jiangzhuo Chen, Anil Vullikanti, Madhav Marathe, Jessica Healy, Rachel B Slayton, Matthew Biggerstaff, Michael A Johansson, Katriona Shea, Justin Lessler

What is already known about this topic?

Increases in COVID-19 cases in March and early April occurred despite a large-scale vaccination program. Increases coincided with the spread of SARS-CoV-2 variants and relaxation of nonpharmaceutical interventions (NPIs).

What is added by this report?

Data from six models indicate that with high vaccination coverage and moderate NPI adherence, hospitalizations and deaths will likely remain low nationally, with a sharp decline in cases projected by July 2021. Lower NPI adherence could lead to substantial increases in severe COVID-19 outcomes, even with improved vaccination coverage.

What are the implications for public health practice?

High vaccination coverage and compliance with NPIs are essential to control COVID-19 and prevent surges in hospitalizations and deaths in the coming months.

Tectonostratigraphic record of late Miocene–early Pliocene transtensional faulting in the Eastern California shear zone, southwestern USA

Released May 14, 2021 08:31 EST

2021, Geosphere

Rebecca J. Dorsey, Brennan O'Connell, Kevin Gardner, Mindy B. Homan, Scott E. K. Bennett, Jacob Thacker, Michael H. Darin

The Eastern California shear zone (ECSZ; southwestern USA) accommodates ~20%–25% of Pacific–North America relative plate motion east of the San Andreas fault, yet little is known about its early tectonic evolution. This paper presents a detailed stratigraphic and structural analysis of the uppermost Miocene to lower Pliocene Bouse Formation in the southern Blythe Basin, lower Colorado River valley, where gently dipping and faulted strata provide a record of deformation in the paleo-ECSZ. In the western Trigo Mountains, splaying strands of the Lost Trigo fault zone include a west-dipping normal fault that cuts the Bouse Formation and a steeply NE-dipping oblique dextral-normal fault where an anomalously thick (~140 m) section of Bouse Formation siliciclastic deposits filled a local fault-controlled depocenter. Systematic basinward thickening and stratal wedge geometries in the western Trigo and southeastern Palo Verde Mountains, on opposite sides of the Colorado River valley, record basinward tilting during deposition of the Bouse Formation. We conclude that the southern Blythe Basin formed as a broad transtensional sag basin in a diffuse releasing stepover between the dextral Laguna fault system in the south and the Cibola and Big Maria fault zones in the north. A palinspastic reconstruction at 5 Ma shows that the southern Blythe Basin was part of a diffuse regional network of linked right-step­ping dextral, normal, and oblique-slip faults related to Pacific–North America plate boundary dextral shear. Diffuse transtensional strain linked northward to the Stateline fault system, eastern Garlock fault, and Walker Lane, and southward to the Gulf of California shear zone, which initiated ca. 7–9 Ma, implying a similar age of inception for the paleo-ECSZ.

Expansion of intertidal mussel beds following disease-driven reduction of a keystone predator

Released May 14, 2021 08:20 EST

2021, Marine Environmental Research (169)

Monica Mei Jeen Moritsch

Disease shapes community composition by removing species with strong interactions. To test whether the absence of keystone predation due to disease produced changes to the species composition of rocky intertidal communities, we leverage a natural experiment involving mass mortality of the keystone predator Pisaster ochraceus from Sea Star Wasting Syndrome. Over four years, we measured dimensions of mussel beds, sizes of Mytilus californianus, mussel recruitment, and species composition on vertical rock walls at six rocky intertidal sites on the central California coast. We also assessed the relationship between changes in mussel cover and changes in sea star density across 33 sites along the North American Pacific coast using data from long-term monitoring. After four years, the lower boundary of the central California mussel beds shifted downward toward the water 18.7 ± 15.8 cm (SD) on the rock and 11.7 ± 11.0 cm in elevation, while the upper boundary remained unchanged. In central California, downward expansion and total area of the mussel bed were positively correlated with mussel recruitment but were not correlated with pre-disease sea star density or biomass. At a multi-region scale, changes in mussel percent cover were positively correlated with pre-disease sea star densities but not change in densities. Species composition of primary substrate holders and epibionts below the mussel bed remained similar across years. Extirpation of the community below the bed did not occur. Instead, this community became limited to a smaller spatial extent while the mussel bed expanded.

Emerging dominance of Paratrochammina simplissima (Cushman and McCulloch) in the northern Gulf of Mexico following hydrologic and geomorphic changes

Released May 14, 2021 07:25 EST

2021, Estuarine, Coastal, and Shelf Science (255)

Alisha M. Ellis, Christopher Smith

Grand Bay estuary in coastal Mississippi and Alabama (USA) has undergone significant geomorphic changes over the last few centuries as a result of anthropogenic (bridge, road, and hardened shoreline construction) and climatic (extreme storm events) processes, which reduce freshwater input, sediment supply, and degrade barrier islands. To investigate how geomorphic changes may have altered the Grand Bay estuary, sediment push cores were collected for foraminiferal, sedimentological (organic matter content, grain-size distribution), and radiochemical (210Pb,137Cs, and 7Be) analyses. Clay normalized geochronologies were determined with a constant rate of supply model. Based on downcore age-depth relationships, select intervals were analyzed for foraminifera in order to assess alterations in the microfossil assemblage in Grand Bay estuary over the 20th Century. All estuarine samples were low diversity (species richness: 1–10; Fisher's alpha diversity: 0.14–1.75); two species, Ammotium salsum and Paratrochammina simplissima, dominated all downcore assemblages. Paratrochammina simplissima increased in abundance up-core from a minor subsidiary species (median = 4.7% at 19–20 cm) to dominant or co-dominant with A. salsum over the 20th and early 21st Centuries in six cores, comprising up to 60.7% of a single sample. The emerging dominance of P. simplissima since ~1950 along with the reduction of brackish-estuarine taxa and introduction of calcareous species signifies increased salinity and less marsh organic matter preserved in the sediments. While seasonal dissolution limits our ability to chronologically constrain the introduction of calcareous species, P. simplissima, a species not referenced in taxonomic data from the northern Gulf of Mexico until 2012, is well constrained, following its first occurrence in the 1930s.

Heat flux from a vapor-dominated hydrothermal field beneath Yellowstone Lake

Released May 14, 2021 07:13 EST

2021, Journal of Geophysical Research (126)

Julia E. Favorito, Robert N. Harris, Robert A. Sohn, Shaul Hurwitz, Karen Luttrell

We report results from 149 heat flux measurements made over n ∼2-year interval at sites in and around a vapor-dominated geothermal field located at water depths of ∼100–120 m in Yellowstone Lake, Wyoming. Measurements of both in situ temperature and thermal conductivity as a function of depth were made with a 1 m probe via a remotely operated vehicle, and are combined to compute the vertical conductive heat flux. Inside the ∼55.5 × 103 m2 bathymetric depression demarcating the vapor-dominated field, the median conductive flux is 13 W m−2, with a conductive output of 0.72 MW. Outside the thermal field, the median conductive flux is 3.5 W m−2. We observed 49 active vents inside the thermal field, with an estimated mass discharge rate of 56 kg s−1, a median exit-fluid temperature of 132°C, and a total heat output of 29 MW. We find evidence for relatively weak secondary convection with a total output of 0.09 MW in thermal area lake floor sediments. Our data indicate that vapor beneath the thermal field is trapped by a low-permeability cap at a temperature of ∼189°C and a depth of ∼15 m below the lake floor. The thermal output of the Deep Hole is among the highest of any vapor-dominated field in Yellowstone, due in part to the high boiling temperatures associated with the elevated lake floor pressures.

Trophic transfer efficiency in the Lake Superior food web: Assessing the impacts of non-native species

Released May 13, 2021 08:05 EST

2021, Journal of Great Lakes Research

Bryan G. Mathias, Thomas R. Hrabik, Joel C. Hoffman, Owen Gorman, Michael J. Seider, Michael E. Sierszen, Mark Vinson, Daniel Yule, Peder M. Yurista

Ecosystem-based management relies on understanding how perturbations influence ecosystem structure and function (e.g., invasive species, exploitation, abiotic changes). However, data on unimpacted systems are scarce; therefore, we often rely on impacted systems to make inferences about ‘natural states.’ Among the Laurentian Great Lakes, Lake Superior provides a unique case study to address non-native species impacts because the food web is dominated by native species. Additionally, Lake Superior is both vertically (benthic versus pelagic) and horizontally (nearshore versus offshore) structured by depth, providing an opportunity to compare the function of these sub-food webs. We developed an updated Lake Superior EcoPath model using data from the 2005/2006 lake-wide multi-agency surveys covering multiple trophic levels. We then compared trophic transfer efficiency (TTE) to previously published EcoPath models. Finally, we compared ecosystem function of the 2005/2006 ecosystem to that with non-native linkages removed and compared native versus non-native species-specific approximations of TTE and trophic flow. Lake Superior was relatively efficient (TTE = 0.14) compared to systems reported in a global review (average TTE = 0.09), and the microbial loop was highly efficient (TTE > 0.20). Non-native species represented a very small proportion (<0.01%) of total biomass and were generally more efficient and had higher trophic flow compared to native species. Our results provide valuable insight into the importance of the microbial loop and represent a baseline estimate of non-native species impacts on Lake Superior. Finally, this work is a starting point for further model development to predict future changes in the Lake Superior ecosystem.

Biogeography and ecology of Ostracoda in the U.S. northern Bering, Chukchi, and Beaufort Seas

Released May 13, 2021 07:39 EST

2021, PLoS ONE (16)

Laura Gemery, Thomas M. Cronin, Lee W. Cooper, Harry J. Dowsett, Jacqueline M. Grebmeier

Ostracoda (bivalved Crustacea) comprise a significant part of the benthic meiofauna in the Pacific-Arctic region, including more than 50 species, many with identifiable ecological tolerances. These species hold potential as useful indicators of past and future ecosystem changes. In this study, we examined benthic ostracodes from nearly 300 surface sediment samples, >34,000 specimens, from three regions—the northern Bering, Chukchi and Beaufort Seas—to establish species’ ecology and distribution. Samples were collected during various sampling programs from 1970 through 2018 on the continental shelves at 20 to ~100m water depth. Ordination analyses using species’ relative frequencies identified six species, Normanicythere leioderma, Sarsicytheridea bradii, Paracyprideis pseudopunctillata, Semicytherura complanata, Schizocythere ikeyai, and Munseyella mananensis, as having diagnostic habitat ranges in bottom water temperatures, salinities, sediment substrates and/or food sources. Species relative abundances and distributions can be used to infer past bottom environmental conditions in sediment archives for paleo-reconstructions and to characterize potential changes in Pacific-Arctic ecosystems in future sampling studies. Statistical analyses further showed ostracode assemblages grouped by the summer water masses influencing the area. Offshore-to-nearshore transects of samples across different water masses showed that complex water mass characteristics, such as bottom temperature, productivity, as well as sediment texture, influenced the relative frequencies of ostracode species over small spatial scales. On the larger biogeographic scale, synoptic ordination analyses showed dominant species—N. leioderma (Bering Sea), P. pseudopunctillata (offshore Chukchi and Beaufort Seas), and S. bradii (all regions)—remained fairly constant over recent decades. However, during 2013–2018, northern Pacific species M. mananensis and S. ikeyai increased in abundance by small but significant proportions in the Chukchi Sea region compared to earlier years. It is yet unclear if these assemblage changes signify a meiofaunal response to changing water mass properties and if this trend will continue in the future. Our new ecological data on ostracode species and biogeography suggest these hypotheses can be tested with future benthic monitoring efforts.