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USGS2026

Extensive glacier loss in the coterminous United States

Glaciers populate the mountain ranges of the western conterminous United States and despite their importance to alpine hydrology, their area and volume change have never been comprehensively evaluated. Since the mid-Twentieth Century about one-quarter of the glaciers have disappeared and the overall area and volume are reduced by one-third. The pattern of glacier shrinkage suggests most glaciers in the Conterminous US are largely maintained by local topographic influences due to their small size. These results are critical to understanding evolving high alpine hydrology and important to ecosystem processes.

conterminous United States↗

USGS2026

Climate change is reshaping seagrass futures: Novel environments and opportunities along coastlines and across oceans

Seagrasses are a highly productive ecosystem that supports biodiversity and fisheries, protects coastlines, and buries globally significant carbon stocks. Because seagrasses are increasingly stressed by warmer, darker, and more variable waters, established management strategies may not guarantee future success. Here, we depict a global outlook for seagrass futures by synthesizing how climate and non-climate human pressures may restructure meadow composition, food webs, fisheries, and blue carbon services. Current seagrass range shifts, adaptations, and acclimations to novel environmental conditions preview future states: climate-tolerant species often become dominant post-disturbance, seeds can disperse hundreds of kilometers, and local management can facilitate habitat persistence and large-scale restoration. To boost climate resilience, we propose a three-part framework involving (1) expanding seagrass mariculture and planting, (2) detecting and predicting shifting stressor gradients and species distributions, and (3) managing for seagrasses tolerant of novel environments. Together, these strategies offer proactive pathways for cultivating climate-adapted seagrass meadows worldwide.

BioScience↗

USGS2026

Phenological flexibility in nesting grassland birds over a half century informs timing of management

The timing of biological events for wildlife species reflects and influences ecological and evolutionary processes and helps guide management actions to meet conservation objectives. Climate change may cause phenological shifts across trophic levels and ecosystems, which can have broad ecological impacts. Shifts may also result in mistiming between management practices based on historical conditions and current biological events, reducing the effectiveness of natural resource management and conservation efforts. We analyzed nesting phenology patterns over recent decades across North America for 44 species of grassland-nesting birds, including waterfowl, upland gamebirds, shorebirds, and passerines, many of which have experienced precipitous population declines. Understanding nesting phenologies of these species is important to their conservation, as grassland management activities often conflict with reproductive periods leading to high nest and young mortality. We compiled a dataset of over 172,000 nest records spanning five decades and evaluated environmental factors influencing long-term shifts and short-term flexibility in nesting phenology. We found considerable variation in responses among species, with differences in both direction and magnitude of spatiotemporal effects on nest initiation dates. Notably, the community-level nesting season lengthened over time, but shifts exhibited spatial heterogeneity within this community of grassland birds. Nesting dates shifted asymmetrically across the breeding season with differential changes in early, peak, and late nesting dates whereas long-term changes were mediated by weather and geographic gradients. For example, nest initiation was earlier in warmer and wetter years. By applying a quantile-based analysis, we provide estimates of the full nesting period that could serve as a flexible tool for scheduling monitoring efforts and balancing management and human activities with periods of reduced nesting activity. Our collaborative effort illustrates the challenges and opportunities of collecting long-term data on avian communities necessary for answering questions across large regions but highlights the value of research coordination for bird conservation.

Global Change Biology↗

USGS2026

Methodology for assessing the accuracy of long-term, annual land cover monitoring at national scale: Experiences from the Land Change Monitoring, Assessment, and Projection (LCMAP) initiative

Annual land cover monitoring using medium-resolution satellite imagery represents a transition from periodic mapping campaigns to continuous observation systems. This transition introduces accuracy assessment challenges not encountered in one-time mapping efforts, particularly when the initial monitoring period is extended forward in time. These challenges are not addressed in existing guidance, which remains largely framed around the evaluation of maps of a single date or maps showing changes between two dates. We present a set of methodological adaptations to adjust to this evolving paradigm, using as a case study the U.S. Geological Survey (USGS) Land Change Monitoring, Assessment, and Projection (LCMAP) initiative, which generated annual land cover and land cover change products across the historical Landsat archive. Assessing the accuracy of these products was an essential component of LCMAP and resulted in an extensive reference sample dataset that may be used for accuracy estimation, area estimation, or support in the development of new algorithms or models. We review the LCMAP methodology and highlight challenges encountered and lessons learned that are transferable to other long-term, temporally dense monitoring programs. This framework demonstrates that statistically rigorous assessment can scale to operational annual land cover production, while the experiences of the project clarify where existing good practice guidance should be extended to support the needs of ongoing, continuous land cover monitoring.

Remote Sensing of Environment↗

USGS2026

Environmental relationships with Silver Carp population ecology across the Mississippi River basin

Objective Silver Carp Hypophthalmichthys molitrix are of special concern to fisheries management agencies across the Mississippi River basin, but effective control of the species is challenging. Our objectives were to (1) identify spatial and environmental patterns among key Silver Carp demographic rates that could be exploited by removal programs and (2) develop predictive models of Silver Carp demographic rates using readily available environmental data that could potentially be used to quantify population ecology without expending the resources to conduct population assessments. Methods We collected Silver Carp from six rivers within the lower Mississippi River subbasin (i.e., Arkansas, Cache, Mississippi, St. Francis, White, and Yazoo rivers) and compiled raw data from populations in the upper Mississippi, Missouri, and Ohio River subbasins to estimate demographic rates (i.e., growth, mortality, and recruitment variability). We compared the demographic rates among subbasins and between main stems and tributaries using standard nonparametric tests. We used information-theoretic model selection to evaluate relationships among demographic rates, environmental conditions, and invasion stage. Results In general, lower Mississippi River subbasin populations exhibited faster growth and lower mortality than did those from the upper Mississippi River subbasin. Populations in main-stem rivers did not differ from those in tributaries. More established populations in warmer, free-flowing rivers (e.g., White River) generally experienced faster growth, lower mortality, and more stable recruitment than less established populations in cooler, impounded rivers (e.g., Illinois River). Conclusions The results indicated that variability in Silver Carp populations was related to environmental conditions and invasion stage. Our results suggested that the effectiveness of removal programs might be improved by targeting populations in warm hydrologically variable rivers, as they may have increased reproduction capacities and emigration rates. The equations provided here may be used to estimate population demographics for Silver Carp and help determine their potential sensitivity to management actions, without expending the resources that are required to collect population-specific biological data.

Mississippi River basin↗

USGS2026

Range-wide population trend analysis for greater sage-grouse ( Centrocercus urophasianus )—Updated 1960–2025

Greater sage-grouse ( Centrocercus urophasianus ; hereafter sage-grouse) are at the center of State and national land-use policies largely because of their unique life-history traits as an ecological indicator for the health of sagebrush ecosystems. This updated population analysis provides State and Federal land and wildlife managers with the best available science to help guide management and conservation plans aimed at benefitting sage-grouse populations and the ecosystems they inhabit. This analysis relied on previously published population modeling methodology from Coates and others (2021, 2022a) and incorporates population lek count data for 1960–2025. Included in this report are methodological updates to period terminology, expanded reporting of trends across all nadir-to-nadir combinations, and revised extirpation probability estimation that utilizes every historic population nadir to forecast abundance. Each of these updates are detailed under individual Modification sections. Additional updates include simulation analyses that evaluate the effects of progressively longer exclusions of Wyoming lek count data (Wyoming Game and Fish Department has not provided access to a complete lek count data set since 2023) on trends, extirpation probabilities, and targeted annual warning system signals. State-space models estimated a 2.7-percent average annual decline in sage-grouse populations between 1966 and 2021 (Period 1–7, six population oscillations) across their geographical range. The average annual decline among climate clusters for the same number of oscillations ranged between 2.0 and 3.5 percent. Cumulative declines were 42.4, 61.7, and 77.9 percent range-wide in Period 5–7 (19 years [two oscillations]), Period 3–7 (36 years [four oscillations]), and Period 1–7 (55 years), respectively. Between 2024 and 2025 (1-year, non-trend timeframe), range-wide population size declined 1.9 percent ( 95-percent credible interval [CRI]= −4.71–1.48). Simulations of missing data from Wyoming showed that progressively longer gaps produced more negative trend estimates and higher extirpation probabilities, predominantly within Wyoming. Effects on targeted annual warning system signals were more nuanced, with missed warnings occurring inside and outside Wyoming and false warnings occurring predominantly within Wyoming.

California, Colorado, Idaho, Montana, Nevada, Nort↗

USGS2026

Mapping groundwater recharge potential and an assessment of available hydrogeologic data within five selected focus areas in eastern Nebraska

Groundwater recharge potential was mapped using airborne electromagnetic survey data collected over the previously glaciated part of eastern Nebraska. To evaluate the appropriate resolution at which airborne electromagnetic data should be interpolated (or represented), we compared a 500-meter cell raster and a filled contour shapefile to known geologic features, point estimates of groundwater recharge, and selected water-quality data. The median groundwater recharge rate for the estimates collected in areas mapped as having high groundwater recharge potential were higher compared to the groundwater recharge rate estimates collected in areas mapped as having moderate and low recharge potential. Selected water-quality data were examined to determine the influence of near-surface geology on water quality, groundwater geochemistry, and groundwater age. The strongest statistical correlations were produced when examining specific conductance values measured from wells in areas mapped as high, moderate, and low groundwater recharge potential. Within till-covered areas, statistically significant differences existed in nitrate, dissolved oxygen, manganese, and iron concentrations sampled from wells mapped in high, moderate, and low groundwater recharge potential areas. Boxplots indicate that till-covered areas mapped as low groundwater recharge potential generally have lower concentrations of nitrate and dissolved oxygen, but higher concentrations of manganese and iron. The Eastern Nebraska Water Resources Assessment project sponsors have identified five focus areas as locations facing unique and important groundwater resource management issues. These focus areas are experiencing the emergence of groundwater resource issues that include increased groundwater development, nitrate contamination, and the potential expansion of rural water districts. Hydrogeologic assessments were completed for the Dorchester-Sterling paleovalley aquifer, Dodge County, Knox County, Burt County, and the Fremont-Arlington-Leshara focus areas. Potential future studies to address data gaps were identified and discussed.

Nebraska↗

USGS2026

Improving predictions of insect harassment for barren-ground caribou in the Arctic

Many populations of barren-ground caribou ( Rangifer tarandus ) have declined or are declining, which is concerning given their ecological role in Arctic ecosystems and their societal role in northern communities. Insect harassment is an important driver of the behavior, energetics, and demographic rates of caribou, and yet, due to challenges in predicting harassment, there is limited understanding of how it is responding to changing Arctic conditions. We investigated environmental correlates of mosquito (Culicidae) and oestrid fly (Oestridae) harassment for the Porcupine caribou herd, with the aim of improving our ability to predict harassment. We collected field observations of mosquito activity and used video collars to detect oestrid fly activity across the summer range, which spans the Alaska–Yukon border. Additionally, we documented the composition of harassing insects collected in malaise traps using DNA metabarcoding. We developed predictive mosquito and oestrid fly harassment models using remotely sensed variables relevant to the insects' biology within a nonlinear modeling framework. We then used the top mosquito and oestrid fly models to hindcast predictions of harassment during 1950–2024 and investigate long-term changes in severity and phenology. The top mosquito harassment model included wind speed, temperature, days since snowmelt, precipitation, topographic position, and soil moisture. The top oestrid fly harassment model included temperature, cumulative growing degree days, and time of day. Harassment of both insects was limited at low temperatures (<10°C), with mosquitoes being additionally limited at high temperatures (>22°C) and wind speeds (>7 m/s). The phenology of mosquito and oestrid fly harassment exhibited curvilinear trends across the summer, peaking in midsummer based on the number of days since snowmelt and cumulative growing degree days, respectively. Mosquito harassment also increased with greater soil moisture, precipitation, and at lower relative elevations. Hindcasting indicated that insect harassment notably intensified and advanced over time. Intensifying harassment could decrease caribou foraging opportunities and body condition, and advancing harassment is likely to increasingly overlap with the calving season when calves are most vulnerable. Our results highlight climate-driven changes in insect harassment and provide improved indices for predicting harassment in the Arctic for future applications.

Alaska↗

USGS2026

Duck nesting response to experimental management of upland habitats in California

Habitat loss and limited upland nesting cover likely constrain waterfowl productivity in intensively managed wetland landscapes in California, USA. We evaluated whether experimental manipulations of upland habitats, including the seeding of native plants, dense nesting cover, or cereal grains, could enhance nesting vegetation and improve duck nest density and nest survival in a Mediterranean climate. During 2008 to 2013, we used a before-after-control-impact (BACI) experimental design within 15 upland grassland fields (each 12–28 ha in size) at a state wildlife area to evaluate habitat management treatment effects on nest site vegetation, vegetation structure, and reproductive performance of mallard ( Anas platyrhynchos ) and gadwall ( Mareca strepera ). The BACI design allowed vegetation and duck nesting responses in treated fields to be compared to untreated control fields both before and after treatment implementation. Prior to treatment implementation, all study fields consisted of upland grasslands dominated primarily by non-native annual grasses typical of Mediterranean-climate ecosystems in California. Relative to control fields, we observed only limited improvement to duck nest success in fields seeded with cereal grains and dense nesting cover, whereas fields seeded with native plants showed persistently lower duck nest survival. Vegetation composition after treatment application shifted rapidly from plants that were purposefully seeded to non-native grasses (e.g., Italian ryegrass [ Lolium multiflorum ]) by the second and third years after treatment. Vegetation structural metrics (i.e., visual obstruction height, lateral density, and canopy density) also showed limited or no improvement attributable to the experimental treatments. Across nearly all treatment and control fields, duck nest densities increased during the first several years following treatment implementation but later declined towards pre-treatment levels by the fourth year after treatment. However, mallard nest densities increased much more markedly in native fields than in control fields in the early post-treatment years but declined again in later post-treatment years, suggesting limited long-term benefit. Clutch size, nest initiation date, and egg hatching success were not affected by treatments. Our results indicate that vegetation management and direct seeding had limited short-term and no measurable long-term benefits to the vegetation's structure, duck nesting densities, or duck nest survival, and upland habitat conditions showed little sustained improvement during later breeding seasons (years 2–4 post-treatment). Upland restoration efforts in agricultural landscapes may need more continued, multi-year habitat management to improve nesting conditions for waterfowl over the long-term.

California↗

USGS2026

On the fidelity of oxygen isotope-based sea level reconstructions: A case study of Marine Isotope Stage 3

Although foraminiferal oxygen isotope records (δ 18 O F ) have long been used to develop time-continuous estimates of past global ice volume, growing evidence indicates that the ice volume and temperature contributions to δ 18 O F diverge considerably over the last glacial cycle. Across Marine Isotope Stage 3 (MIS 3; 57 to 29 ka), estimates of peak global sea level based on δ 18 O F are ∼30 m lower than reconstructions based on recent glacial geology, geologic sea-level records, and glacial isostatic adjustment (GIA) modeling approaches. Here we address this mismatch by quantifying uncertainties in converting δ 18 O F to global sea level during MIS 3. We review the geochemical tools to assess the contributions of ocean temperature, diagenesis, and the isotopic composition of ice sheets to δ 18 O F records across MIS 3. We show that recent advances in our understanding of these and other factors that contribute uncertainty (e.g., global sea level during the Last Glacial Maximum) help to explain the MIS 3 gap between global sea level estimates based on δ 18 O F and GIA analyses of geologic sea-level records. We find that the accuracy and precision of MIS 3 ocean temperature reconstructions is likely a key contributor, and various MIS 3 temperature reconstructions can reduce the “gap” by 30%–70% (∼10–20 m). Future improvements in the precision of temperature reconstructions will better constrain the ice volume component of δ 18 O F records. Ultimately, assessing the fidelity of δ 18 O F as a proxy for global ice volume is key to disentangling the feedbacks between climate and ice sheets over the Pleistocene.

Paleoceanography and Paleoclimatology↗

USGS2026

Arctic Grayling, scared to death: Are Brown Trout an impediment to Arctic Grayling reintroduction success in Michigan?

Introduction: Arctic Grayling Thymallus arcticus were extirpated from Michigan in 1936. Their demise was caused by over-fishing, habitat destruction from large-scale logging, and Brook Trout Salvelinus fontinalis and Brown Trout Salmo trutta. Subsequently, Brook and Brown trout have become the dominant salmonid species in Michigan streams. Past attempts to restore Grayling to Michigan have been unsuccessful perhaps due to competition with these now resident salmonids. Objective: To determine the impacts of competition between age-0 Arctic Grayling and age-0 Brook and Brown Trout on Grayling growth and survival. Methods: Competition trials were performed in experimental streams, lasting two months, across three years, with three treatment types: the control, 10 Grayling with 10 Grayling; the Brook Trout treatment, 10 Grayling with 10 Brook Trout; and the Brown Trout treatment, 10 Grayling with 10 Brown Trout. Results: Brown Trout had a significant effect on Arctic Grayling growth and mortality, while Brook Trout had no effect on Arctic Grayling growth or mortality. Conclusion: Age-0 Brown Trout negatively impacted growth, condition, and survival of age-0 Arctic Grayling, while the impacts of age-0 Brook Trout or conspecifics were negligible. This suggests reintroduction of Arctic Grayling may be more successful in streams with few or no Brown Trout.

Michigan↗

USGS2026

Detecting polar bears on land using satellite imagery and deep learning

Summer land use is increasing for polar bears in the Beaufort Sea, which may lead to increases in human-bear interactions. Remote methods may enable noninvasive approaches to monitor polar bear abundance and distribution on land. We examined the potential of using very high-resolution optical satellite imagery to detect polar bears on land from images collected at three sites on the Beaufort Sea coast of Alaska. Additionally, we evaluated the use of deep learning models to automate detection of polar bears in these images and the degree to which detection of polar bears differed among three very high-resolution optical satellite missions. Pléiades Neo images exhibited 90% average precision in validation analyses using a faster region-based convolutional neural network model, which was 55% and 11% greater than the average precision using WorldView-2 or -3 images, respectively. Applying the Pléiades Neo training set to new imagery exhibited lower precision (35%), but high recall (100%), which indicates that deep learning could be used to expedite the visual detection of polar bears in imagery. Very high-resolution optical satellite imagery provides a remote method for monitoring polar bears on land where they occur in high densities, but satellite mission, off-nadir angle, pansharpening methods, and image resolution are important considerations.

Alaska↗

USGS2026

Quality of groundwater used for domestic supply in the western Central Valley, California—2023

More than 2 million Californians rely on groundwater from domestic wells for their drinking-water supply. This report summarizes a 2023 California Groundwater Ambient Monitoring and Assessment Priority Basin Project water-quality survey of 44 domestic and small-system drinking-water supply wells in the western Sacramento Valley (basin number 5-021) and San Joaquin Valley (basin number 5-022) groundwater basins in the Central Valley, California, where more than 88,000 residents are estimated to utilize privately owned, domestic wells. The study area includes the Corning, Colusa, Yolo, and Solano subbasins (subbasin numbers 5-021.51, 5-021.52, 5-021.67, and 5-021.66, respectively) of the Sacramento Valley groundwater basin, and the East Contra Costa, Tracy, Delta-Mendota, and Westside subbasins (subbasin numbers 5-022.19, 5-022.15, 5-022.07, and 5-022.09, respectively) of the San Joaquin Valley groundwater basin. The study was focused on groundwater resources used for domestic drinking-water supply, which are mostly drawn from shallower parts of the aquifer system rather than groundwater resources used for public drinking-water supply, which are typically drawn from deeper parts. This assessment characterized the quality of ambient groundwater used for domestic supply, rather than the quality of drinking water at a tap or faucet, which may be filtered or treated after extraction. To provide context, concentrations of constituents in groundwater were compared to Federal and State of California regulatory and non-regulatory benchmarks for drinking-water quality. Regulatory benchmarks were U.S. Environmental Protection Agency and State of California maximum contaminant levels (MCLs) for drinking water. Non-regulatory benchmarks were State of California secondary maximum contaminant levels (SMCLs) for managing aesthetic conditions, such as taste, odor, or color. A grid-based method was used to estimate the areal proportions of groundwater resources used for domestic drinking supply that have water-quality constituents present at high concentrations (greater than the benchmark), moderate concentrations (between one-half of the benchmark and the benchmark for inorganic constituents, or between one-tenth of the benchmark and the benchmark for organic constituents), and low concentrations (less than one-half or one-tenth of the benchmark for inorganic and organic constituents, respectively). This method provides statistically representative results at the study-area scale and permits comparisons to other California Groundwater Ambient Monitoring and Assessment Priority Basin Project study areas. In this study, inorganic constituents in groundwater were greater than regulatory benchmarks for public drinking-water quality in 30 percent of domestic groundwater resources. Inorganic constituents present at concentrations greater than MCLs for drinking water were hexavalent chromium, total chromium, and nitrate. Total dissolved solids, manganese, and iron were present at concentrations greater than their SMCL in 27 percent of domestic groundwater resources. 1,2,3-trichloropropane was present at concentrations greater than State of California MCLs for drinking water in 2.3 percent of domestic groundwater resources and was the only volatile organic compound detected at concentrations greater than a benchmark. Per-and polyfluoroalkyl substances were detected in 16 percent of domestic groundwater resources, and 2.3 percent had concentrations greater than U.S. Environmental Protection Agency MCLs. Total coliform bacteria and enterococci were detected in 9.1 and 2.3 percent of domestic groundwater resources, respectively. To understand groundwater quality in the study area, factors that affect groundwater quality were evaluated using results from statistical testing of associations between constituent concentrations and potential physical and chemical variables. Relevant factors include the oxidation-reduction conditions of groundwater, agricultural land use, and geologic sources of aquifer sediments. Manganese and iron concentrations were affected by oxidation-reduction state. Nitrate concentrations were affected by the interplay of agricultural practices and denitrification, where denitrification under anoxic redox conditions can mitigate some nitrate derived from fertilizer application. Ultramafic aquifer sediments in the western Central Valley provide a geogenic source for chromium and hexavalent chromium. Total dissolved solids primarily were derived from water-rock interactions with soils and aquifer materials, but agricultural practices may also contribute to these concentrations.

California↗

USGS2026

From transcriptomic dysregulation to behavioral impairment: Mechanistic effects of weathered Brazilian oil on early life stage fish

The 2019–2020 oil spill along the northeastern coast of Brazil affected coastal reef ecosystems and the organisms that inhabit these environments. To characterize the toxicity of persistent weathered oil residues to early life stage fish, embryonic zebrafish ( Danio rerio ) were exposed to environmentally relevant concentrations of a water-accommodated fraction (WAF) prepared from weathered oil recovered following the spill. Embryos were exposed from 24 to 168 h postfertilization (hpf) to low (2.14 μg ∑PAH 60 L –1 ) and high (17.1 μg ∑PAH 60 L –1 ) concentrations representative of chronic postspill exposure conditions. Transcriptomic profiling revealed early alterations in pathways associated with connective tissue, cardiovascular, and respiratory development at 48 hpf, which corresponded with a significant reduction in heart rate at 72 hpf. By 96 and 168 hpf, molecular responses shifted toward visual system dysfunction, including pathways related to photoreceptor development and phototransduction. Histological evaluation confirmed significant thinning of retinal layers, consistent with impaired retinal development or photoreceptor degeneration. These structural changes translated to functional impairment, as larvae exhibited a 40% reduction in optokinetic response. These integrated analyses identify mechanistic targets of weathered oil toxicity and establish molecular to behavioral relationships that improve understanding of chronic oil spill impacts on early life stage fish.

Pernambuco↗

USGS2026

Long-term trends of selected pesticides in the Little Arkansas River, south-central Kansas, 1995–2023

The eastern part of the High Plains Aquifer, herein called the Equus beds aquifer, is currently a primary source of water (2026) for the city of Wichita, Kansas. The Equus Beds Aquifer Storage and Recovery Project was developed in the early 1990s to meet future water demands by using the Little Arkansas River as an artificial aquifer recharge water source during above-base-flow conditions in the river. Little Arkansas River water is diverted at an intake structure, treated following National Primary Drinking Water Regulations as a guideline, and delivered to the aquifer through recharge basins or injection wells for later use. The U.S. Geological Survey, in cooperation with the city of Wichita, completed the study described in this report to quantify and characterize Little Arkansas River water-quality data. Data in this report can be used to evaluate changing conditions in aquifer recharge source water, provide science-based information for decision making, and help meet regulatory monitoring requirements. Continuous streamflow, specific conductance, turbidity, and discrete atrazine data were collected from two Little Arkansas River study sites and discrete glyphosate and aminomethylphosphonic acid was collected from one of the two Little Arkansas River study sites from 1995 to 2023 to evaluate water-quality conditions and assess pesticide trends. Pesticide trends in the herbicides atrazine and glyphosate and the herbicide-associated compound aminomethylphosphonic acid (a glyphosate degradate) were evaluated using the R package seawaveQ. Pesticides modeled with the seawaveQ R package had increasing and decreasing trends during the study period, depending on the individual pesticide and if there were strong seasonal patterns; larger estimated concentrations occurring in late spring and early summer. Modeled atrazine concentrations exceeded the Federal maximum contaminant level of 3 micrograms per liter about 8 percent of the time at both study sites. Atrazine had a nonsignificant increasing trend (98 percent) at the Highway 50 site and a nonsignificant decreasing trend (31 percent) at the downstream Sedgwick site during the study period. Glyphosate and aminomethylphosphonic acid trends were not evident at the Sedgwick site during the study period.

Kansas↗

USGS2026

Authoritative knowledge infrastructure for GeoAI: Implications for scientific spatial data providers

Geospatial Artificial Intelligence (GeoAI) increasingly relies on automated analysis of authoritative geospatial data, exposing limitations in data infrastructures originally designed for simple dissemination rather than for knowledge-driven use. From the perspective of scientific spatial data providers, the challenge is enabling GeoAI responsibly while retaining semantic clarity, provenance, reproducibility, and governance. This short paper (i) examines how GeoAI exposed limitations within existing geospatial data infrastructures, and (ii) identifies provider-side requirements for an authoritative knowledge infrastructure. Drawing on GIScience, scientific workflow, and operational AI literature, the paper outlines implications for national mapping organizations that seek to support advanced analytics without jeopardizing scientific rigor or stewardship responsibilities.

Conference Paper↗

USGS2026

Probabilistic forecasting of coastal wetland elevation and soil carbon response to sea-level rise

Tidal wetlands build soil as a dynamic response to inundation, resulting in carbon sequestration and resilience to sea-level rise. Process models can be used to make site-specific forecasts, anticipate future changes, and plan management responses. But to be actionable, forecasts from these models need to be accompanied by descriptions of their confidence. In this study, we demonstrate the application of ecological forecasting principles to the unique case of tidal wetland vulnerability and carbon storage, given accelerating and uncertain sea-level rise. We present a case study using the Cohort Marsh Equilibrium Model at the Global Change Research Wetland in Maryland, USA. We used meta-analyses to quantify lab- and sample-level measurement uncertainties for common soil measurements and to develop Bayesian model priors. Reanalysis of previous literature supported predictive relationships between belowground turnover and mean annual temperature, as well as between soil erodibility and suspended sediment concentration that could be transferable to other locations. The model forecasted a likely conversion of low-elevation marsh to open water by the 2060s, accompanied by a decrease in marsh carbon storage capacity. Forecasted uncertainty in elevation was dominated by structural uncertainty in the model, while carbon accumulation rates were more influenced by parameter uncertainty. After 2050, and increasingly as the forecast approached 2100, uncertainty in sea-level rise projections contributed to uncertainty in both forecasts. Forecasts were most sensitive to processes related to organic matter preservation, plant productivity (maximum aboveground biomass and belowground turnover), and organic soil packing density. The soil formed was an organic-rich peat (>70% organic matter according to the data), and model predictions were insensitive to parameters associated with mineral sedimentation. We identify additional field data collection, such as on decomposition trajectories and plant productivity, and data-model coupling of near-term elevation records as the most impactful strategies for reducing uncertainties in future forecasting efforts. Future work can build on this forecasting framework in other locations, using it for adaptive management, identifying appropriate interventions to mitigate wetland loss, and projecting future carbon removal capacity in response to accelerated sea-level rise.

Maryland↗

USGS2026

An examination of the reasons for, and variability of, the differences between response spectra and pseudo response spectra

For many decades, it has been common practice to overlook the differences between response spectra and pseudo response spectra. This practice stems from analyses indicating that the average difference between response spectra and pseudo response spectra is negligible for a viscous damping ratio of 5%, which is near-universally adopted. As others have shown, the differences depend strongly on the damping ratio, earthquake magnitude, and oscillator period, with larger differences for larger damping, smaller magnitudes, and longer periods. To quantify the full statistical distribution of the ratio of the absolute acceleration response spectrum (SA) to the pseudo absolute acceleration response spectrum (PSA), we fit empirical ratios with the generalized gamma distribution. Data for magnitudes from 4.0 to 5.5 give 95% prediction intervals for the ratio of 1.00–1.02 at 1 s and 1.01–2.24 at 10 s for 5% damping. For 30% damping, these intervals increase to 1.14–2.01 at 1 s and 1.62–11.8 at 10 s, respectively. Further, we demonstrate how the shape of the ground-motion Fourier amplitude spectrum interacts with the natural period of the oscillator to control the differences in the response spectra type. Routinely treating the two measures of acceleration response spectra as interchangeable may lead to unacceptable inconsistencies when the response spectra of individual records are important or when larger damping ratios are used, such as in direct displacement-based design. If one must convert between them, the uncertainty of the conversion should be accounted for during analysis.

Earthquake Spectra↗