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USGS2026

Toxoplasma gondii: Challenges and perspectives in interpreting longitudinal seroprevalence data for a chronic parasitic infection

Toxoplasma gondii —the causative agent of toxoplasmosis—is a zoonotic pathogen of warm-blooded hosts. Infection causes mild-to-severe symptoms, including lethargy, fever, muscle pain, abortion, ocular disease, and encephalitis. Toxoplasma affects many vertebrate species, although felids are the only known definitive hosts. Seroprevalence in wildlife is often assessed using cross-sectional data, but few studies have tracked individual-level infections through time. We present a 4-yr dataset from white-tailed deer ( Odocoileus virginianus ) with repeated sampling of individuals that highlights challenges associated with assigning serostatus to individuals. Using a modified agglutination test, we observed seroconversion from seronegative to seropositive within individuals, as expected. Although toxoplasmosis is known to be a chronic disease, we also found reversion from seropositive to seronegative. Accurate assignment of serostatus is necessary for evaluating effects of infection on behavioral and physiologic outcomes. However, longitudinal data from individuals whose titers oscillate around the positive threshold present novel challenges. Therefore, we discuss the implications for assigning serostatus for chronic toxoplasmosis infection for three proposed approaches: 1) ever positive, always positive; 2) negative until positive and then always positive; and 3) status by sampling period. Clarifying which approach is used to assign serostatus when analyzing longitudinal T. gondii data may enable more meaningful comparisons across systems and studies.

Journal of Wildlife Diseases↗
USGS2026

Preface

Despite more than 50 years of research into the human dimensions of recreational f isheries, there is no textbook to present the theoretical grounding, operationalisation, and interpretation of the most elemental social components involved in fisheries management – namely, outcomes and trade-offs, behaviours (and antecedents or predictors of it), and the relationships among actors (fishers, f isher groups, managers, and management organisations). The objective of this edited volume is to reduce this knowledge gap. The book comprises four parts: (I) recreational fisheries as social-ecological systems, (II) disciplinary views of f ishers’ behaviours and outcomes, (III) engagement of fishers to support effective social science, and (IV) interdisciplinary integration for recreational fisheries management. Part I provides the general motivation for an interdisciplinary approach to understand recreational fisheries as coupled systems. Part II provides the foundations of various social science disciplines and highlights linkages and differences in the underlying theories and concepts used. Part III describes various qualitative and quantitative methods to study the social aspects of recreational fisheries in more detail, and Part IV suggests approaches to achieve standardisation and integration of different data streams, including how to link social and ecological data. The book chapters have been written by leading scholars of recreational fisheries science, involving social and economic scientists, political ecologists, and fisheries ecologists with a tradition in either applying human dimensions or working towards integration.

Book chapter↗
USGS2026

Colorado River basin

Flowing 1,450 miles through seven states and 30 Tribal Nations, the Colorado River is known as the lifeline of the Southwest. The river delivers water to 40 million people, irrigates approximately five million acres of farmland, supports a trillion-dollar economy, and supplies hydroelectric power to millions. Its drainage basin stretches across 250,000 square miles of diverse ecosystems, providing habitat for thousands of plant and wildlife species. However, increasing temperatures have altered the amount and timing of annual snowmelt and streamflow, exacerbating drought conditions and diminishing reservoir storage levels. Over time, less water becomes readily available for the communities, ecosystems, and economies that rely on the river’s consistent flow.

Arizona, California, Colorado, Nevada, New Mexico,↗
USGS2026

Conventional hydrothermal power-producing systems of the Great Basin, USA

As part of the update to the electric-grade conventional hydrothermal assessment of the Great Basin, USA, Monte Carlo analyses of identified resources within explored regions will be performed to make estimates of discovered resources and associated uncertainty. Analyses use conditional statistics where estimates are conditioned upon a hydrothermal favorability map, allowing for the likelihood that more resources exist in regions of higher hydrothermal favorability. For these analyses, a dataset of identified hydrothermal systems is compiled, and the new compilation is described herein. Recognizing that a single hydrothermal system may be developed with multiple power plants, and that the hydrothermal upflow zone may be several kilometers across with many measurements characterizing a single hydrothermal system, a procedure was developed and employed to create clusters of points (power plants, measurements, etc.) that are associated with a single system, and a new central point was defined as the best estimator of the center of the hydrothermal system. Hydrothermal systems were uniquely identified by grouping electric-grade hydrothermal measurements and operating power plants within a distance of 10 km. Groups that are >10 km apart are assumed to be different electric-grade hydrothermal systems. While 10 km was used as the threshold, most systems were significantly further apart, and most points within groups were typically within 5 km of each other. A well measurement was considered an electric-grade measurement of a hydrothermal system if it had two properties: a measured temperature of >85 °C and evidence of hydrothermal convection. Other points that were added to the dataset are locations of operating powerplants or locations that have been classified as an electric-grade hydrothermal resource by either the U.S Geological Survey (USGS) or the Great Basin Center for Geothermal Energy. After all points are assigned to systems, new points were computed with the goal of identifying the center of the throat of the hydrothermal upflow zone. If operating powerplants exist for a system, then the arithmetic average of all power plant locations is used. Otherwise, if USGS made an estimate, that location is used. In the absence of both powerplants or USGS estimates, the arithmetic average of all electric-grade measurement locations is used. An example is shown of how these newly compiled locations might be ranked for uncertainty analyses, where higher confidence is assumed if measured temperature is higher and there are many supporting measurements indicating an electric-grade resource. In summary, 28 systems have operating power plants, an additional 78 systems are known identified electric-grade hydrothermal resources, and 99 new systems were identified as probable electric-grade systems with varying levels of confidence. These 205 locations are shown as a function of a recent hydrothermal favorability map, conceptually illustrating the conditional statistics that can be used to make estimates of the undiscovered resources of the Great Basin. An accompanying data release provides summaries of developed capacity by system and USGS estimates of likely total capacity and associated uncertainty.

Arizona, California, Idaho, Nevada, Oregon, Utah↗
USGS2026

Science for drought response

Droughts impact water availability and quality, agriculture, energy production, ecosystem health, cultural resources, and wildfire risk. In an average year, nearly 15% of the US experiences significant drought, and in some recent years, drought conditions have impacted more than a third of the nation (U.S. Drought Monitor). The U.S. Geological Survey (USGS) Climate Adaptation Science Centers (CASCs) deliver actionable science to help land and resource managers prepare for, reduce the risk of, and recover from drought.

Report↗
USGS2026

Lower Eastern Shore Tributary summary: A summary of trends in tidal water quality and associated factors, 1985-2023

The Lower Eastern Shore Tributary Summary outlines change over time according to a suite of monitored tidal water quality parameters and associated potential drivers of those trends for the period 1985 – 2023, and provides a brief description of the current state of knowledge explaining these observed changes. Water quality parameters described include surface (above pycnocline) total nitrogen (TN), surface total phosphorus (TP), surface water temperature (WTEMP), spring (March-May) and summer (July-September) surface chlorophyll a, summer bottom (below pycnocline) dissolved oxygen (DO) concentrations, and Secchi disk depth (a measure of water clarity). Results for annual bottom TP, bottom TN, surface ortho-phosphate (PO4), surface dissolved inorganic nitrogen (DIN), surface total suspended solids (TSS), and summer surface DO concentrations are provided in an Appendix B. Drivers discussed include physiographic watershed characteristics, changes in TN, TP, and sediment loads from the watershed to tidal waters, expected effects of changing land use, and implementation of nutrient management and natural resource conservation practices. Factors internal to estuarine waters that also play a role as drivers are described including biogeochemical processes, physical forces such as winddriven mixing of the water column and increase in rainfall intensity and volume, and biological factors such as phytoplankton biomass and the presence of submersed aquatic vegetation. Continuing to track water quality response and investigating these influencing factors are important steps to understanding water quality patterns and changes in the Lower Eastern Shore. The intended audiences for this report include, but are not limited to, 1) technical managers within jurisdictions who use tidal water quality to inform management decisions, 2) local watershed organizations that are trying to understand these analyses and working to connect them to their local area(s), and 3) federal, state, and academic researchers. Figure 1 presents a conceptual model highlighting these intended audiences. The Tributary Summary documents are sources of readily available background for change over time in tidal water quality observed with monitoring data. They help answer questions related to water quality, show how landscape factors drive water-quality changes over time, provide support for management decisions that may alter water quality trends and living resources conditions, and highlight where there may be information or knowledge gaps.

Maryland, Virginia↗
USGS2026

Understanding flooding and channel dynamics along the Taiya River: Providing context for resource management

Flooding and channel change in the Taiya River Basin in recent decades have directly affected park infrastructure and cultural resources. The complexities of flooding and channel change are compounded by the changing sediment and flow regime from a changing climate and shrinking glaciers, which will continue to drive dynamic riverine change. Streamflow data and geomorphic interpretation helped us place these events in context to inform decision making that takes dynamic natural processes into account.

Alaska↗
USGS2026

Brewing change in the (glacier) percolation zone

Alaska's glaciers are losing mass at the fastest rate of any region globally, significantly affecting both the volume and distribution of water across the landscape. Though glaciers in the Alaska region (as defined by glaciologists this includes both Alaska and portions of adjacent Canada) range from sea level to nearly 6200 m (20,320 ft), the majority of glacier area in the Alaska region is concentrated between 900 and 2100 m (2950 to 6890 ft). Long term glacier monitoring in Alaska by the U.S. Geological Survey (USGS) Benchmark Glacier Project is on moderate-sized glaciers with distributions of glacier area in this elevation range. These are some of the longest in-situ records of glacier mass change in the world. The process-based understanding of glacier change on those “Benchmark Glaciers” is robust, but it is limited to the range of conditions present on those particular glaciers—at moderate elevations—where large amounts of melt water and rain pass through the glacier and into the downstream ecosystem on an annual basis.

Alaska↗
USGS2026

Intertidal community responses to perturbations along Alaska park coastlines

Nearshore ecosystems are highly productive zones with strong connections to both terrestrial and open ocean ecosystems. The rocky intertidal is a highly dynamic ecosystem and changes over a variety of spatial and temporal scales depending on the factors contributing to the change. Here we summarize how nearshore communities and species responded to several perturbations to intertidal communities within Alaska’s coastal national parks.

Alaska↗
USGS2026

Prince William Sound Herring Program, fiscal year 2024

Pacific herring ( Clupea pallasii ) were collected from three sites in Prince William Sound (PWS), Alaska (Table 1) during the spring pre-spawn period from March 29 – April 1, 2024, to test for viral hemorrhagic septicemia virus (VHSV), viral erythrocytic necrosis (VEN), and Ichthyophonus prevalence (Table 1). Ichthyophonus was detected in 33% (59/180) of heart cultures from all sites combined. An inverted pattern of decreasing Ichthyophonus infection prevalence with size started around 2019 and continued through 2024 (Fig. 1). VHSV was isolated from one fish collected in Canoe Pass. The isolation was at a very low titer and was detectable only after blind passage. Neutralizing antibodies to VHSV were detected in 4.4% (14/318) of PWS herring in 2024 (Fig. 2). Erythrocytic inclusions indicative of VEN were not detected in any PWS herring (n =180) from 2024, but bacterial rods were noted in the blood films from three fish.

Alaska↗
USGS2026

Bottom trawl assessment of Lake Ontario’s benthic prey fish community, 2025

Since 1978, bottom trawl surveys in Lake Ontario have provided information on the status and trends of the benthic prey fish community related to Fish Community Objectives that include understanding prey fish population dynamics and community diversity. Beginning in 2015, the benthic prey fish survey expanded from only U.S. sites to incorporate Canadian sites, increasing the survey’s spatial coverage to a lake-wide scale. Additionally, sampling in the eastern U.S. embayments (Black River, Chaumont, Guffin, and Henderson Bays), that were historically sampled during a September bottom trawl survey to index Yellow Perch ( Perca flavescens ; 1978-2007), resumed in 2015. The current survey provides abundance indices for sculpins, Round Goby ( Neogobius melanostomus ) and Bloater ( Coregonus hoy i) using techniques, gear, and timing comparable to surveys on Lake Michigan. This alignment provides a necessary biological reference point for evaluating Lake Ontario Bloater reintroduction. In 2025, the benthic prey fish survey completed 100 bottom trawl sites across main lake and embayment habitats at depths from 6 to 168 m. Sampling in US waters was limited in 2025 compared to previous years. In total, the 2025 survey sampled 59,870 fish from 23 species. No Bloater were detected in the 2025 survey. Round Goby was the most common species comprising 46% of the total catch by number, followed by Deepwater Sculpin ( Myoxocephalus thompsonii ), White Perch ( Morone americana ), and Alewife ( Alosa pseudoharengus ) at 23%, 9%, and 9% respectively. Slimy Sculpin ( Cottus cognatus ) lake-wide biomass density continues to be lower than when lakewide sampling began in 2015; zero Slimy Sculpin were detected in US waters, however sampling in the main lake within US waters was limited to the southeastern area of Lake Ontario. Deepwater Sculpin biomass has remained high since population recovery began in 2010. Embayment sampling in 2025 was limited to only Chaumont Bay.

Lake Ontario↗
USGS2026

Inland habitat selection model for wintering whooping cranes

Inland habitat use by wintering Aransas-Wood Buffalo whooping cranes ( Grus americana ) is expected to increase given projected population growth and observations of some whooping cranes using inland winter habitat in addition to coastal marshes. We developed resource utilization functions using ‘random forests’ to model whooping crane use as a function of environmental covariates considered important for whooping crane use. Covariates associated with distance to cropland, distance to development, and wetness or standing water were the most influential in model prediction. The model estimated that the 50% predicted use contour encompassed 34,925 hectares (ha) and the 95% predicted use contour encompassed 328,928 ha within the study area. While presently limited by the small sample size of inland wintering areas observations ( n = 7 cranes with ≥50 locations), this model provides an initial tool for identifying potential impacts to whooping crane inland habitat use in proximity to anthropogenic development. The model can be expanded to incorporate future data to reduce uncertainty.

Texas↗
USGS2026

Stopover population estimate and migration ecology of Red Knots C. c. rufa at Delaware Bay, USA, 2025

Red Knots( Calidris canutus rufa ) rely on Atlantic horseshoe crab ( Limulus polyphemus ) eggs in the Delaware Bay to refuel during northward migration. Intensive harvest of horseshoe crabs in the 1990s contributed to declines in Red Knot numbers. In 2013, the Atlantic States Marine Fisheries Commission adopted an Adaptive Resource Management (ARM) framework to balance sustainable horseshoe crab harvest with ecosystem integrity and Red Knot recovery, requiring annual stopover population estimates. We estimated the 2025 passage population of Red Knots at Delaware Bay using a Bayesian analysis of a Jolly–Seber mark–resight model which accounts for population turnover and imperfect detection. We also evaluated change in migration timing between 2011 and 2025 with model-derived estimates of arrival at the Delaware Bay each year. The 2025 passage population was 54,043 individuals (95% credible interval: 47,926–61,928), an increase of approximately 17% over 2024 and only the second year since 2011 to exceed 50,000 individuals. Despite the increase, overlapping credible intervals across years indicate a stable stopover population. Migration timing has remained consistent, with 50% of the population typically arriving by 18 May and no evidence of advancement since 2011. These findings provide meaningful input for the ARMframework, supporting sustainable harvest of horseshoe crabs while maintaining adequate foraging opportunities for Red Knots and other shorebirds.

Delaware, New Jersey↗