Geology topics

Research about United States

Source-linked reports with geographic coverage including United States.

At least 37 records · Page 2Linked to original sources

USGS2026

Humans experienced abrupt environmental changes at White Sands during the Last Glacial Maximum

Expanded excavations at White Sands National Park have unearthed 20 stratigraphic horizons containing in situ human footprints, megafaunal trackways, and linear features created by travois. Advances in radiocarbon dating of conifer pollen, combined with ages of aquatic seeds, refines the chronology of the footprint-bearing sequence to between 23.5 and 21.7 thousand years ago (ka). Biomarker, pollen, and stratigraphic evidence indicate a complete overturning of the environment from a perennial lake to a playa and capture a large aridification episode coincident with Dansgaard-Oeschger event 2 at 23.2 ka, which shrank pluvial Lake Otero and allowed people to traverse the former shoreline area for nearly two millennia. This well-dated and highly resolved paleoclimate record provides compelling evidence that humans in North America experienced marked environmental changes during the Last Glacial Maximum.

New Mexico↗

USGS2026

Terrain-based map of mélange and intact rock at the junction of Coastal and Central Belt rocks of the Franciscan Complex between Gualala and Ukiah, northern California Coast Ranges

A terrain-based map of a large area of Franciscan Complex between the San Andreas and Maacama faults east of Point Arena, California, provides much new detail compared to prior mapping. The new map reveals an unusual, structurally disrupted area that is defined by northwest-trending patches of erosionally resistant topography interspersed in subdued topography. These two terrain types, here termed Hard and Soft, are distinguished using differences in the detailed shapes of individual topographic elements that in these rocks are indicative of relatively intact rock and severely sheared mélange. The disrupted area lies at the junction between rocks of two different parts of the Franciscan Complex: sandstone and argillite of the Coastal belt to the northwest and mélange and variously metamorphosed sandstone and other rocks of the Central belt to the southeast. The rocks in the disrupted area seem to consist largely of Coastal belt sandstone interspersed in Central belt mélange. They are separated from areally continuous Coastal belt to the west by the newly defined Cedars fault and from continuous mélange of the Central belt to the east by the newly defined Boonville fault. A plausible history to account for Coastal belt rocks and Central belt mélange now interspersed at the same structural level in the disrupted area is westward thrusting of Central belt over Coastal belt on the Coastal belt thrust, located mostly above the present level of exposure, followed by extensional dip-slip faulting involving both the disrupted area and its bounding faults. Most of the study area has been mapped on the ground only in reconnaissance. The terrain map was prepared largely by interpretation of small-scale aerial photographs, with distinctions in the steepness of slopes and curvature of ridge and side-hill crests made from the photographs. These distinctions were then confirmed by differences in their areal abundance determined through quantitative mapping of slope and curvature. Most of the remainder of the map was prepared in the same fashion directly from the slope and curvature maps. Geologic identities are assigned to as much of the area as possible, but some resistant parts, mostly in the disturbed area, remain identified solely as Hard terrain. Some units, mostly along the southern edge of the map, are compiled from published sources. This report serves as a description and explanation of the associated spatial database (Wentworth, 2025), which consists of attributed line and polygon shape files and metadata describing them.

California↗

USGS2026

Improving estimates of spatially distributed agricultural land use using pesticide data

Accurate, spatially resolved agricultural land-use data are essential for estimating water demand, evaluating agricultural production, and understanding long-term changes in managed landscapes. However, existing land-use datasets are often temporally discontinuous, particularly for historical periods, and remotely sensed classifications face persistent challenges distinguishing spectrally similar crop types, capturing sub-annual rotations, and separating active from abandoned plantings. We developed the California Pesticide Use Reporting Land-Use Estimator (CalPUR-LUE), which converts grower-reported pesticide-application records into annual estimates of land use by crop class and cropped acreage at approximately 1-square-mile resolution across California. CalPUR-LUE performance was evaluated for 2018 using complementary spatial, categorical, and quantitative comparisons with California Department of Water Resources (CADWR) remotely sensed land-use data and county-level agricultural economic reports. At the county-meridian-township-range-section (COMTRS) scale, CalPUR-LUE and CADWR acreage estimates showed substantial proportional agreement (log-transformed Lin’s concordance correlation coefficient = 0.77) with a mean proportional bias of −15%. Crop-class agreement was high when CalPUR-LUE identified agricultural activity, with user’s accuracy exceeding 83% for all evaluated crop classes. Overall categorical agreement was 67% (Cohen’s kappa = 0.56). Grain crop underestimation contributed substantially to disagreement; however, there is evidence of CADWR systematic overestimation of grain during 2016–2019. County-level agricultural reports further corroborated CalPUR-LUE estimates and, in several cases, aligned more closely with CalPUR-LUE than with CADWR. These results demonstrate that pesticide-use reporting provides an independent and complementary source of agricultural land-use information that can corroborate contemporary estimates and reconstruct annual spatially distributed land use where historical data are limited.

California↗

USGS2026

Diet and trophic ecology of invasive Blue Catfish Ictalurus furcatus in an eastern shore tributary of the Chesapeake Bay

Blue Catfish Ictalurus furcatus were first introduced to Virginia tributaries of the Chesapeake Bay in the 1970s and have greatly expanded in population size and distribution, prompting ecological and economic concerns. This study investigates the diet and trophic ecology of invasive Blue Catfish in tidal, low-salinity reaches of the Nanticoke River and Marshyhope Creek, on the Chesapeake Bay’s Eastern Shore (Maryland, USA), using complementary stomach content (SCA) and stable isotope (SIA) analyses. Stomach contents from Blue Catfish ( n = 363 non-empty stomachs) were collected opportunistically from October 2021 through November 2022. For SIA, 136 individuals across 21 fish species, blue crab Callinectes sapidus , and arrow arum Peltandra virginica were sampled between October 2021 and October 2023. SCA revealed considerable seasonal and size-based diet variability, suggesting a shift from omnivory to piscivory at 563 mm total length. Primary prey included fish, arrow arum seeds, Asian clams Corbicula fluminea , and amphipods, along with seasonally available species of economic and ecological importance (river herring Alosa spp., blue crab, White Perch Morone americana , and Atlantic Menhaden Brevoortia tyrannus ). Minimal isotopic niche overlap between large and small Blue Catfish size classes, alongside ontogenetic trends in δ 13 C and δ 15 N, substantiated SCA-detected diet shifts. Trophic level estimates derived from Blue Catfish δ 15 N ( n = 54 individuals) were higher than those from SCA, particularly for individuals <563 mm. Blue Catfish occupied a relatively high trophic level, and carbon and sulfur SIA indicated marine resource utilization, substantiating SCA results. This research describes localized trophic interactions of invasive Blue Catfish to inform fishery management planning regarding Blue Catfish’s potential influence on other species of management interest.

Delaware, Maryland↗

USGS2026

Fluvially-sourced sediment supply and climate modulate morphodynamics and state transitions in bistable aeolian dunefields

Alternative stable state theory in aeolian geomorphology describes the occurrence of bare and vegetated aeolian dunes in response to long-term climatic and ecological drivers. Transitions between states, as well as their co-occurrence (bistability), can arise from perturbations to drivers, disturbance, and associated biophysical feedbacks. Here, we examine the role of upwind fluvial sediment disturbance as a driver of aeolian state transitions. We analyze 24 source-bordering aeolian dunefields along 400 km of the Colorado River in Grand Canyon, USA, where active and inactive aeolian dune states occur downwind of fluvial sediment sources. Four decades of topographic change detection following upstream dam emplacement revealed that active aeolian dunes—which had indicators of recent aeolian transport—experienced four times more surface change than inactive dunes lacking such indicators of recent aeolian transport. Persistent aeolian activity occurred where bare upwind fluvial sandbars were maintained as sediment sources, whereas transitions toward inactivity accompanied the loss of bare sandbars and resulted in 50% less topographic change. Contrary to theory, the transition to aeolian inactivity did not correspond to significant reductions in erosion, despite decreased topographic changes. These results broadly demonstrate the effects of biophysical feedbacks within fluvially sourced aeolian environments. Specifically, they show that reductions in aeolian activity are not synonymous with geomorphic quiescence, as other sedimentary processes may become dominant agents of change within these coupled sedimentary systems that are ubiquitous throughout dryland regions on Earth.

Arizona↗

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

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

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

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

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

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

Characterizing metabolic responses of Eleutherodactylus frogs in Puerto Rico to different thermal treatments: Implications for conservation

Amphibians are increasingly vulnerable to extinction due to physiological stress induced by projected global warming and associated drying trends. Understanding the underlying mechanisms and consequences of these responses is crucial to developing effective conservation strategies. Puerto Rico hosts 15 endemic Eleutherodactylus frog species, which are particularly vulnerable to environmental changes due to poor vagility and narrow thermotolerance. In this study, we report routine metabolic rates (RMRs) of four species in response to four temperature treatments (15, 20, 25 and 30°C) at two temporal scales (24 and 72 hours) using indirect calorimetry. Results indicated that three species exhibited increased RMR with rising temperatures. The RMR at 25°C for E. wightmanae was spurious, and it was the only species that did not survive at 30°C. The Arrhenius breakpoint analysis indicated that E. juanariveroi RMR decreased between 25 and 30°C. In contrast, E. antillensis and E. coqui RMR increased with increasing assay temperatures. We discuss how diel metabolic demands decrease the scope at both thermal extremes for E. antillensis and E. coqui , and how habitat temperature may impinge energetic challenges to those coping with documented warming trends, such as E. wightmanae .

Puerto Rico↗

USGS2026

Water quality improvements and hydrogeomorphic change over 20 years contributed to macrophyte community recovery in the Upper Mississippi River

Several large rivers across the globe have recently undergone noticeable improvements to water quality. Yet, the cascading ecological consequences for aquatic life, including macrophytes, are largely unknown, owing to the lack of suitable long-term data and the difficulty of modelling community-level responses. Our study leveraged multiple big datasets from 1998 to 2019 within a 400-km stretch of the Upper Mississippi River in the United States, which experienced major changes to hydrogeomorphology, water quality, and climate during the 22-year study. These decadal changes resulted from both natural processes, such as increased discharge and hydrologic connectivity, and targeted management actions, including water quality improvements and restorations. Using joint species distribution models, we showed how changes to hydrogeomorphology and water quality increased macrophyte taxonomic and ecological (trait) diversity at a macroscale. We uncovered substantial macrophyte community recovery as evidenced by increased species prevalence and diversity, as well as favorable community trait shifts from undesirable free-floating plants towards desirable submersed plants. Submersed species were positively associated with water quality improvements (specifically, reduced concentrations of total phosphorus, chlorophyll a , and total suspended solids). However, total nitrogen concentration modestly increased over the 22-year period and nearly all macrophyte species were locally absent or negatively affected by high nitrogen values. Pollination mode and life form traits responded to environmental changes; as examples, submersed plants recovered with water quality improvements and epihydrophilous plants that pollinate on the water's surface increased with hydrogeomorphic connectivity. Water quality improvements explained approximately 25%–40% of the macrophyte community's temporal variation. Other major environmental drivers of macrophyte distribution included spatial variations of water depth and velocity. Macrophyte community assembly was shaped partially by strong temporal changes in hydrogeomorphology and water quality, and to a greater extent the spatial habitat heterogeneity within the large riverscape.

Iowa, Illinois, Minnesota, Wisconsin↗

USGS2026

Application of close-kin mark–recapture to an American black bear population using harvest samples

Close-kin mark–recapture (CKMR) offers a promising alternative to traditional mark–recapture methods for estimating wildlife population parameters. CKMR estimates demographic parameters by identifying genetic relationships between individuals, effectively “recapturing” parental genotypes through their offspring's genetic profiles. One key advantage of CKMR over traditional methods is the ability to estimate abundance without recapture, facilitating the use of lethally collected biological samples. Here, we present an application of CKMR to a terrestrial species using samples collected from harvested individuals. We analyzed genetic data from 1767 American black bears ( Ursus americanus ) harvested over two consecutive years in Michigan's Upper Peninsula. Using Genotyping-in-Thousands by sequencing (GT-seq), we identified parent-offspring pairs and developed sex-specific models tailored to black bear reproductive biology and management strategies. Female population estimates aligned with our expectations, based on prior knowledge of the population. In contrast, male population estimates deviated from expectations, potentially due to an unmodeled combination of factors pertaining to male reproductive biology and sampling bias. Our study not only demonstrates the viability of using harvest-based CKMR for monitoring of terrestrial wildlife populations, but also highlights the need for careful model specification. By providing a novel method to estimate demographic parameters and population size, CKMR using harvest samples can inform management decisions and harvest quotas. This approach leverages existing management practices involving collection of genetic samples, such as mandatory harvest registrations and health monitoring programs. Our findings contribute to the growing body of CKMR applications and expand its use to terrestrial species management.

Michigan↗