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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 1,081 records · Page 60Linked to original sources
USGS2026

Growth form and lifespan of herbaceous species mediate the role of traits in short-term drought response

Increased climate variability is expected to intensify short-term drought events. Plants have evolved stress tolerance strategies involving trade-offs in resource conservation, mycorrhizal collaboration and plant size, yet how these strategies promote drought resistance across different herbaceous plant groups remains unknown. Leveraging 63 globally distributed grassland and shrubland sites from the International Drought Experiment, we identified plant traits linked to drought resistance in 661 populations of 421 species after 1 year of extreme drought. We assessed how traits, site precipitation and drought severity affected cover change across growth forms and lifespans, and how trait–environment interactions influenced drought resistance. Across all species, leaf N (an acquisitive trait) was associated with drought resistance, whereas in forbs, drought resistance was also associated with a conservative root trait and plant size. In addition, interactions among traits mediated drought resistance; root traits predicted performance only in concert with other traits. Environmental variables influenced trait effects on drought resistance, notably for annuals in wetter sites, suggesting that drought-escape strategies in annuals may be advantageous only under mild stress. Our study highlights variability in traits that predict drought resistance across herbaceous plant groups, emphasizing the importance of species context, environmental stress and the selection of traits in research and management.

Nature Ecology and Evolution↗
USGS2026

Using eye lens stable isotopes to identify the rearing origin of fall age-0 walleye ( Sander vitreus )

Isotope values in fish eye lenses may be useful in differentiating rearing origins. We compared eye lens isotopic values of fall fingerling age-0 walleye ( Sander vitreus ) reared in a hatchery pond, a recirculating aquaculture system (RAS), and a natural lake. Using 10 fish per rearing source, we delaminated layers from one eye lens per fish to assess temporal changes in carbon (δ 13 C) and nitrogen (δ 15 N) and pulverized the whole second eye lens for δ 13 C, δ 15 N, and sulfur (δ 34 S). RAS-reared walleye values exhibited high precision among individuals and were δ 34 S enriched. Pond-reared walleye had lower δ 13 C and δ 15 N core values compared to other rearing sources. For δ 13 C and δ 15 N, values remained consistent among layers for RAS-reared walleye, δ 15 N slightly increased for pond-reared and lake-reared walleye, and δ 13 C increased substantially among subsequent layers in pond-reared walleye. Bayesian 95% ellipses did not overlap among rearing sources. These results demonstrate that eye lens stable isotope analysis may be a useful tool for differentiating hatchery-reared and wild large fingerling walleye, specifically from RAS- and pond-reared sources.

South Dakota↗
USGS2026

Assessment of undiscovered conventional oil and gas resources in the Santos Basin, Campos Basin, and Espírito Santo Basin provinces of Brazil, 2024

Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean conventional resources of 10.4 billion barrels of oil and 53.3 trillion cubic feet of gas in the Santos Basin, Campos Basin, and Espírito Santo Basin provinces of Brazil.

Campos Basin, Espírito Santo Basin, Santos Basin↗
USGS2026

Gambel’s quail (Callipepla gambelii) nest site selection and habitat use in Oracle Junction, Arizona

Gambel’s quail ( Callipepla gambelii ) is the most widespread, abundant, and heavily harvested species of game quail in Arizona. Gambel’s quail population dynamics in Arizona are strongly influenced by seasonal weather conditions. This is particularly relevant for Gambel’s quail management as drought conditions are expected to increase in Arizona, and this may exacerbate inter-annual variation in Gambel’s quail abundance and recruitment. The goal of this study is to provide information on Gambel’s quail population demographics, habitat use, and movement to inform land management decisions for Gambel’s quail in southeast Arizona in a way that mitigates the effect of drought. We used multiple trapping methods to capture Gambel’s quail from February–July 2024 and February–15 May 2025. We found noose mats (n = 57) to be more effective than drop traps (n=14) in capturing Gambel’s quail, with multiple types of walkin traps proving ineffective. We deployed 33 GPS backpack transmitters on female Gambel’s quail to monitor their movements and locate nests. We documented eight mortalities of tracked quail from apparent predation. Quail home range sizes ranged from 3 ha-100 ha (mean = 25 ha) in 2024 and from 7–57 ha (mean = 29 ha) in 2025. We identified four nest sites with 6-15 eggs and all nests were predated. We collected vegetation measurements at nest and brood sites and corresponding random points to examine nest and brood site selection although our small sample sizes limited our ability to make inferences about Gambel’s quail habitat selection.

Arizona↗
USGS2026

Variation in pathogen load and the pathogen load–infectiousness relationship broaden avian malaria’s distribution

Two aspects of host infectiousness shape pathogen transmission and distribution but are underappreciated: the relationship between pathogen load and infectiousness, and variability in pathogen load within species. We quantified the relationship between host pathogen load (parasitemia) for avian malaria ( Plasmodium relictum ) and infectiousness for biting Culex quinquefasciatus mosquitoes with experimental infections in canaries ( Serinus canaria ). Using this relationship, we estimated the infectiousness of 17 bird species in 11 communities in Hawaiʻi and quantified the relative contributions of infection stage (acute versus chronic) to transmission. We show that infectiousness to mosquitoes increased with parasitemia, temperature, and time since feeding. The relationship’s gradual (low) parasitemia slope resulted in a wide range of parasitemias being partly infectious, and high within-host species variability in parasitemia led to extensive overlap in infectiousness among hosts. Disproportionate mosquito host utilization (inferred from relative infection prevalence) elevated the importance of a few host species, yet broad overlap in species infectiousness resulted in similar total infectiousness across most bird communities. This similarity likely contributed to avian malaria’s widespread distribution throughout Hawaiʻi despite diverse host community assemblages. Our findings highlight the importance of both the shape of the pathogen load–infectiousness relationship and within-species variability in determining a pathogen’s host range, transmission intensity, and spatial spread.

Nature Communications↗
USGS2026

Post-wildfire water quality and aquatic ecosystem response in the U.S. Pacific Northwest: science and monitoring gaps

An increase in the occurrence of large, high severity wildfires in the western Pacific Northwest (PNW), USA, has created an urgent need for science to better inform forest management and policy decisions to maintain source water quality in the region. The western PNW faces similar challenges to other regions with shifting wildfire regimes and large population centers reliant on surface water from forested catchments. However, the uniquely wet and highly seasonal climate of the western PNW suggests that findings from other, more frequently burned regions may not be directly applicable. To identify science, monitoring, and management gaps and opportunities in the western PNW, this review was collaboratively undertaken by academics, non-government and industry representatives, and local, state, and federal government entities who have been working together since the 2020 Labor Day fires in Oregon. Focusing on Oregon and Washington, we found that monitoring networks for continuous water quantity and quality cover much of the state with greater representation in western U.S. ecoregions, but few studies have analyzed and published these data to capture and communicate the post-wildfire response. Approximately half of the streamgages in Oregon and Washington record major water quality parameters, and hundreds of sites in the area have discrete sampling for a wide range of water quality constituents. Still, numerous gaps exist in understanding the short- and long-term impacts of wildfire on hydrology, water chemistry, including pH and dissolved oxygen, mobilization of metals, aquatic ecosystems, and downstream drinking water treatment. Collective action to further collect, analyze, interpret, and publish the key data could help improve our understanding of post-wildfire water quality impacts in this and other increasingly wildfire-affected regions.

Oregon, Washington↗
USGS2026

Drivers of disperser immigration into cooperatively breeding carnivore groups

Dispersal is a fundamental process that shapes social groups by affecting genetic diversity, group composition, and social dynamics through immigration and subsequent settlement. In group-living animals, dispersal involves more than just leaving 1 group and arriving at another because dispersers also need to be accepted at an established group for successful dispersal to occur. Understanding how and why new individuals integrate into established social groups remains a key question, particularly when the benefits to existing members are unclear. This question persists in part because the ecological and social conditions that shape disperser settlement remain poorly understood. We leveraged an existing harvest regime and examined 18 years of life-history data from a wild population of cooperatively breeding gray wolves ( Canis lupus ) to understand immigration dynamics of group-living. Specifically, we tested how social and environmental conditions within groups predicted the likelihood that a disperser successfully immigrated into a group, analyzing how breeder turnover, annual harvest, group size, and genetic relatedness influenced that decision. Turnover of breeding males had the strongest effect on the probability of disperser settlement, suggesting that the loss of key social roles may create opportunities for new individuals to join groups. We also found an interaction between group size and harvest. By quantifying conditions that shape immigrant settlement, we highlight a mechanism influencing the stability and structure of cooperatively breeding groups. Unlike studies focused on individual dispersal decisions, our research highlights how variation in ecological and social conditions shape settlement into groups by dispersers.

Idaho↗
USGS2026

Using structured decision making to evaluate the tradeoffs of selective fish passage

Dams have dramatically altered rivers and are a major contributor to native fish population declines. However, many dams serve important ecological, social, and economic functions, such as flood control, invasive species control, and provision of recreational opportunities. Therefore, dam removal is often contentious among stakeholders and involves making tradeoffs among multiple competing objectives. This research uses structured decision making to evaluate the ecological, social, and economic consequences and tradeoffs of enhancing connectivity for migratory fishes in the Boardman River, Michigan. We describe efforts to engage a diverse group of stakeholders to elicit their objectives under various fish passage alternatives. We used multi-attribute tradeoff methods to help stakeholders weigh the costs and benefits of enhancing connectivity for several fish species with varying life history traits and initial distributions. We found that the optimal alternative was passage of native fishes only; however, the optimal alternative varied based on the weight stakeholders might place on each objective. We created four objective weighting scenarios to evaluate the sensitivity of the optimal alternative to changes in objective weights. This research will help inform decision-makers on fish passage alternatives that are preferred by stakeholders and that are likely to achieve their objectives.

Michigan↗
USGS2026

Design and functionality analysis of the high-stress permeameter (HSP), a device developed for measuring mechanical and hydraulic properties of gas hydrate-bearing pressure core

To characterize sediment compressibility and permeability in the presence of gas hydrate, a naturally occurring combination of water and methane that requires elevated pressure and reduced temperature to remain stable, a high-stress permeameter (HSP) device was developed. The HSP was designed to accept gas hydrate-bearing pressure core specimens in their plastic liner at pressures of 10–11 MPa. The HSP was further designed to carry out compressibility and permeability tests over a range of effective stresses while maintaining the requirements for gas hydrate stability. To verify the validity of HSP measurements of sediment consolidation properties, we tested remolded kaolin samples in the HSP and three standard fixed-ring oedometers. Furthermore, we compared the direct fluid-flow permeability measurements from the HSP with estimates based on Terzaghi’s log-time method for calculating permeability from 1-dimensional oedometer-style consolidation tests. We found agreement between all devices for consolidation (e.g., coefficients of compressibility and recompression) and permeability results. These findings indicate the suitability of the HSP for consolidation tests, as well as the log-time method for estimating permeability from oedometer consolidation tests.

Geotechnical Testing Journal↗
USGS2026

Preface to the focus section on intraplate earthquakes

More than a half century after plate tectonics provided an overarching framework to explain earthquakes along active plate boundaries, numerous theories have been proposed to explain where, why, and how often earthquakes occur well away from active plate boundaries, but a paradigm remains elusive. Even the classification of earthquakes away from active plate boundaries as "intraplate" raises issues, with potentially important distinctions between Stable Continental Regions and more actively deforming regions including passive margins and failed rifts. Some of the largest known intraplate earthquakes themselves remain enigmatic, having occurred before the modern instrumental era. Hazard assessments are often data-limited: low fault-slip rates relative to landscape modification rates result in poor discoverability of fault sources, challenging the characterization of source zones and earthquake recurrence; the completeness and homogenization of instrumental earthquake catalogs using uncertain magnitude conversions can lead to uncertainties in earthquake recurrence; and, limited strong-motion observations for large-magnitude events at near-source distances leads to uncertainties in the selection and development of ground-motion models for seismic hazard studies. Data from recent intraplate earthquakes around the world—from the moment magnitude M 7.7 2001 Bhuj, India, earthquake 25 years ago to the 2024 M 4.8 Tewksbury, New Jersey earthquake—have yielded both new insights and new questions. The papers in this special focus discuss many of the long-standing challenges involved with intraplate earthquake investigations and provide a snapshot of the state of the art with current research to advance our understanding.

Seismological Research Letters↗
USGS2026

Background, methods, goals, challenges, opportunities, and information needs

Understanding how climate change and variability will impact grassland ecosystems is crucial for successful grasslands management in the future. In 2020, the North Central Climate Adaptation Science Center began a project to establish a baseline of information to best serve grassland managers (that is, those individuals who develop grassland management plans, implement those plans on the ground, or both) at Federal, State, and Tribal agencies; nongovernmental organizations; and partnerships to help meet regional grassland management goals. This chapter presents the main findings from the review and synthesis of 183 grassland management-related documents relevant to the North Central region. Specifically, this chapter describes the methods by which grassland management-related documents were identified, reviewed, and synthesized; defines five North Central Grassland Ecoregions; provides a synthesis of regional grassland management goals and challenges; identifies information needs relevant to grassland management in a changing climate; and summarizes grassland management issues by ecoregion.

Colorado, Kansas, Montana, Nebraska, North Dakota,↗
USGS2026

Day-roost use by ‘ōpe‘ape‘a, the Hawaiian hoary bat (Lasiurus semotus)

The ‘ōpe‘ape‘a, also known as the Hawaiian hoary bat ( Lasiurus semotus ; family Vespertilionidae), is a solitary, insectivorous, foliage-roosting endemic species. Over a three-year period, we investigated day-roost lability and fidelity of 35 bats at 52 roosts (for a total of 544 days of observation), and roost emergence and return patterns of 46 bats at 50 roosts (for a total of 277 days of observation). ‘Ōpe‘ape‘a exhibited low roost lability, typically using few roosts and switching roosts infrequently. Juveniles and reproductive females exhibited particularly low lability, whereas non-reproductive adults, especially males, displayed higher lability. Roost fidelity was generally high, with most bats consistently returning to the same roost or set of roosts. We also evaluated long-term use of roosts at 20 trees from 2019 to 2022. Six roost trees were used over a span of at least 180 days, and of these, three were used by multiple individuals that included maternity groups. We documented a maternity ‘cluster’ composed of multiple neighboring roosts used by different mother-pup groups and solitary bats during the same reproductive season. Measures of day-roost emergence times, nocturnal period spent at roosts, and number of nighttime departures showed high variability, were not significantly different among sex or reproductive groups and exhibited no seasonal trends. The study demonstrated that ‘ōpe‘ape‘a generally remain at the same day-roost for extended periods, unlike other tree-dwelling species, particularly lasiurines. The findings also suggest that individuals may prioritize familiar roosts and home range resources over exploring new roosts, potentially due to the permanence of suitable foliage roosts and predator avoidance strategies.

Hawaii↗
USGS2026

American kestrel population trends and vital rates at the continental scale

The American kestrel ( Falco sparverius , hereafter referred to as kestrel) has declined across much of its North American range since at least the mid-1960s. Kestrel population dynamics have been explored through a multitude of local studies and two broad reviews of available data. Across large geographic extents, however, the demographic cause(s) of kestrel population declines remain(s) largely unknown. As part of a collaborative effort to elucidate the drivers of kestrel population declines, we developed a continental-scale integrated population model using band-recovery data, productivity data, and Breeding Bird Survey indices from 1986 to 2019 to estimate indices of annual population sizes, survival, and productivity rates across the continental United States. We detected a decline in population size of ~1%–2% per year. Overall estimates of population growth from 1986 to 2019 suggest a 29% decline in population size (95% CI = −34% to −23%). There was little evidence of a trend in brood size. However, survival of juvenile birds (mean = −0.015, SD = 0.008 and mean = −0.024, SD = 0.010 for females and males, respectively) and adult males (mean = −0.016, SD = 0.010) in the summer declined, suggesting that these vital rates could be contributing to declines in populations over time. Winter adult survival rates (mean = −0.004, SD = 0.009 and mean = −0.009, SD = 0.010 for females and males, respectively) also declined but to a lesser extent than summer survival. For juvenile birds, winter survival increased (mean = 0.006, SD = 0.008 and mean = 0.002, SD = 0.009 for females and males, respectively); however, this was not enough to offset declines in summer survival and annual survival rates declined over the time series. Annual adult survival was also low relative to previous research on kestrel survival rates. Given the importance of survival to population trends, our findings provide support for several previously proposed broad classes of factors potentially contributing to observed population declines: declines in arthropod prey, second-generation rodenticides, neonicotinoid insecticides, and predation.

Ecosphere↗
USGS2026

Bascom Laser Diffraction Sedimentology Laboratory, Reston, Virginia

Introduction At the Bascom Laser Diffraction Sedimentology Laboratory, which is located in the Florence Bascom Geoscience Center at U.S. Geological Survey (USGS) headquarters in Reston, Virginia, scientists use physical sedimentology and particle characterization techniques to conduct detailed sediment characterization. Scientists address research problems in collaboration with other USGS science centers, State geological surveys, commercial industry, universities, and other partners. Laboratory capabilities include laser diffractometry for quantitative particle-size analysis, portable x-ray fluorescence (XRF) analysis for determining elemental abundances in rock or sediment samples, petrographic analysis of geologic media, and mechanical sieve analysis. These methods are used to analyze soil and sediment core material from terrestrial, marine, and lacustrine environments, surface sediments from coastal regions, and calcareous materials. Work done by the laboratory supports geologic mapping, resource assessments, land change studies, and geohazard analyses.

Fact Sheet↗
USGS2026

Stepovers and beyond: Structural control of The Geysers geothermal system and the broader Clear Lake region

Fault geometry exerts a first-order control on geothermal systems by governing stress localization, fracture development, and permeability, yet in complex fault networks or broader shear zones, the relative influence of individual geometric features is often difficult to resolve. In the northern California Coast Ranges, The Geysers geothermal field is commonly interpreted to occur within a releasing stepover, although no single, clearly defined stepover is identified in published studies. To investigate the structural controls on The Geysers and the broader Clear Lake region, a two-dimensional elastic boundary element model is developed to evaluate spatial patterns of dilational strain associated with progressively more complete fault geometries. Model results show that dilation in the region is not controlled by a single structure but instead reflects the combined effects of multiple interacting fault elements. Three primary controls are identified: (1) opposing bends in the regional strike-slip fault system, including a releasing bend along the Maacama fault; (2) the southern fault tip of the Collayomi fault, which generates a prominent dilational lobe beneath the southern Geysers; and (3) a releasing stepover between the Collayomi fault and the Geyser Peak–Mercuryville–Big Sulphur Creek fault system, inferred to collectively behave as a right-lateral shear zone bounding the western margin of The Geysers. Predicted dilational strain magnitudes are sufficient to localize permeability between faults. These results highlight that incorporating complete fault networks and bedrock geological mapping can enhance geothermal assessments and provide a transferable framework for evaluating structurally controlled permeability in tectonically active regions.

California↗
USGS2026

Per- and polyfluoroalkyl substances in waters associated with oil and gas development in the Denver Basin

Use of per- and polyfluoroalkyl substances (PFAS) in the petroleum industry could be a cause for concern due to the large volumes of produced water (PW) generated during oil and gas extraction, the reuse of these wastes in water-stressed regions, and adverse health outcomes related to PFAS exposures. However, PW PFAS characterization is nearly absent in the literature, and hydraulic fracturing (HF) chemical disclosures often omit the identities of additives as proprietary. Here we evaluate PFAS in PW samples from three petroleum wells in the Denver Basin during their first year of production. Total concentrations of targeted PFAS (Σ 40 PFAS) were < 35 ng/L in PW samples, with short-chain PFAS like perfluorobutanoic acid persisting throughout the sampled duration. Analysis of freshwater inputs for hydraulic fracturing (Σ 40 PFAS ~ 113 ng/L) and mixed fracture fluid (Σ 40 PFAS ~ 69 ng/L) indicated much of the targeted PFAS content was derived from the input water, and not from HF additives, however samples subjected to oxidation indicated the presence of PFAS precursors that would not be detected by targeted analysis. This study highlights that while PFAS content is low in the studied PWs, the potential for redistribution of PFAS in the environment may be a consideration for reuse applications.

Colorado, Nebraska, Wyoming↗
USGS2026

Chronic wasting disease (CWD) knowledge, risk perception, and management acceptance are influenced by media engagement and trust among deer hunters in Massachusetts

Prior to wildlife disease emergence, public outreach campaigns can improve disease-related knowledge and increase the likelihood that stakeholders accept potential management actions. One wildlife disease of particular interest is chronic wasting disease (CWD), which is spreading across the United States but has not been detected in Massachusetts. We conducted a survey of deer hunters ( n = 7,419) in Massachusetts to: (1) explore media channel usage and source trust, and (2) assess the relationship among CWD knowledge, risk perception, management acceptability, and state wildlife agency trust. We found that channel usage and source trust varied by socio-demographic factors. We also found that engagement with popular channels and trust in accurate sources were positively correlated with CWD knowledge. CWD risk perception mediated the relationship between knowledge and management acceptance, and trust was positively associated with management acceptance. Collectively, our results indicate a mixed-media campaign by state wildlife agencies could improve CWD management acceptance.

Massachusetts↗