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At least 595 records · Page 33Linked to original sources
USGS2010

Importance of coastal change variables in determining vulnerability to sea- and lake-level change

In 2001, the U.S. Geological Survey began conducting scientific assessments of coastal vulnerability to potential future sea- and lake-level changes in 22 National Park Service sea- and lakeshore units. Coastal park units chosen for the assessment included a variety of geological and physical settings along the U.S. Atlantic, Pacific, Gulf of Mexico, Gulf of Alaska, Caribbean, and Great Lakes shorelines. This research is motivated by the need to understand and anticipate coastal changes caused by accelerating sea-level rise, as well as lake-level changes caused by climate change, over the next century. The goal of these assessments is to provide information that can be used to make long-term (decade to century) management decisions. Here we analyze the results of coastal vulnerability assessments for several coastal national park units. Index-based assessments quantify the likelihood that physical changes may occur based on analysis of the following variables: tidal range, ice cover, wave height, coastal slope, historical shoreline change rate, geomorphology, and historical rate of relative sea- or lake-level change. This approach seeks to combine a coastal system's susceptibility to change with its natural ability to adapt to changing environmental conditions, and it provides a measure of the system's potential vulnerability to the effects of sea- or lake-level change. Assessments for 22 park units are combined to evaluate relationships among the variables used to derive the index. Results indicate that Atlantic and Gulf of Mexico parks have the highest vulnerability rankings relative to other park regions. A principal component analysis reveals that 99% of the index variability can be explained by four variables: geomorphology, regional coastal slope, water-level change rate, and mean significant wave height. Tidal range, ice cover, and historical shoreline change are not as important when the index is evaluated at large spatial scales (thousands of kilometers). ?? 2010 Coastal Education and Research Foundation.

Journal of Coastal Research↗
USGS2013

Development of a stock-recruitment model and assessment of biological reference points for the Lake Erie walleye fishery

We developed an updated stock–recruitment relationship for Lake Erie Walleye Sander vitreus using the Akaike information criterion model selection approach. Our best stock–recruitment relationship was a Ricker spawner–recruit function to which spring warming rate was added as an environmental variable, and this regression model explained 39% of the variability in Walleye recruitment over the 1978 through 2006 year-classes. Thus, most of the variability in Lake Erie Walleye recruitment appeared to be attributable to factors other than spawning stock size and spring warming rate. The abundance of age-0 Gizzard Shad Dorosoma cepedianum, which was an important term in previous models, may still be an important factor for Walleye recruitment, but poorer ability to monitor Gizzard Shad since the late 1990s could have led to that term failing to appear in our best model. Secondly, we used numerical simulation to demonstrate how to use the stock recruitment relationship to characterize the population dynamics (such as stable age structure, carrying capacity, and maximum sustainable yield) and some biological reference points (such as fishing rates at different important biomass or harvest levels) for an age-structured population in a deterministic way.

North American Journal of Fisheries Management↗
USGS2026

Assessing environmental drivers of denitrification in restored riverine floodplains

Restoration of impaired floodplains is an increasingly prevalent strategy for alleviating water quality concerns and reducing downstream flooding at watershed scales. Floodplains temporarily store water and slow flow velocity to promote sedimentation during overbank flooding and remove inorganic nitrogen from floodwater and groundwater via denitrification. Evaluating the impacts of different restoration strategies on denitrification can inform more strategic investments into floodplain modifications that improve water quality outcomes. Our research investigates how denitrification rates in floodplains respond to environmental factors that are actionable from an engineering perspective through design and water resources management. We seasonally measured soil denitrification enzyme activity and various environmental characteristics in 4 floodplains with different restoration design and management approaches at the confluence of the Wabash and Tippecanoe Rivers in Indiana, United States. Our results showed that denitrification rates in an agricultural floodplain were significantly lower than in restored floodplains with native vegetation. Certain soil conditions characteristic of floodplain wetlands were associated with higher denitrification, particularly elevated total nitrogen, moisture, silt, and organic matter contents. Vegetation species composition was correlated with denitrification rates. This link may reflect the direct effects of vegetation on soil conditions, such as supplying labile organic carbon, or indirect effects, such as vegetation acting as an indicator of hydrologic regime and land use. Denitrification seasonally varied, peaking in winter when nitrate supply from rivers draining agricultural watersheds in the region is also high. Substrate limitation of soil denitrification enzyme activity was most significant during the summer when overbank flooding, which replenishes soil nitrogen stocks, rarely occurs. Our findings indicate that denitrification capacity will likely be maximized in riverine floodplains that are restored as wetlands with diverse native vegetation and enhanced hydrologic connectivity. Such restoration activities promote higher denitrification rates via elevated moisture, fine sediment deposition, and soil organic matter.

Tippecanoe River, Wabash River↗
USGS2023

Insectivorous bat foraging tracks the availability of aquatic flies (Diptera)

Rivers and their adjacent riparian zones are model ecosystems for observing cross-ecosystem energy transfers. Aquatic insects emerging from streams, for example, are resource subsidies that support riparian consumers such as birds, spiders, lizards, and bats. We collaborated with recreational river runners in Grand Canyon, Arizona, USA, to record acoustic bat activity and sample riparian insects using light traps at dusk from April through October 2017–2020. River runners collected these data on 1,428 events over 611 sampling nights at 410 sites throughout a 470-km segment of the Colorado River. We documented 71 insect taxa in light traps and recorded 19 bat species with acoustic detectors. We hypothesized that bat activity along this highly regulated river segment would be influenced primarily by variation in prey availability, as compared to other habitat descriptors. We predicted that bat activity would be positively related to aquatic insect catch rates and unrelated to terrestrial insect abundance. We fit Bayesian regression models to test these hypotheses and to quantify the relationship between bat activity and a suite of environmental variables: time of year, time of day, distance from perennial tributaries, distance from rapids, channel width, geomorphic reach, tall vegetation cover, air temperature, and lunar phase. Bat activity was positively related to the abundance of aquatic flies (Diptera), which outcompeted all other prey categories and structural habitat descriptors in our models. Within our dusk sampling period, activity of small myotis (California myotis [ Myotis californicus ] and Yuma myotis [ M. yumanensis ]) was high late in the evening and canyon bats ( Parastrellus hesperus ), conversely, were more active early in the evening. Activity of canyon bats varied seasonally, with peak activity in August. Our results support the hypothesis that aquatic prey, specifically aquatic flies, are key predictors of bat activity along a large, regulated river corridor and demonstrate the power of community science as a tool for ecosystem monitoring.

Journal of Wildlife Management↗
USGS2025

One hundred ninety-nine dead birds: Review of the scientific basis of ecological incident reporting requirements for pesticide registrants under Fifra § 6(A)(2)

The U.S. Environmental Protection Agency (EPA) regulates pesticide use in the United States. The EPA is charged by the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) with ensuring that a pesticide will not cause unreasonable adverse effects on the environment. Incident reports (documentation of exposure and injury from pesticide applications) can serve as a reality check on the pesticide registration decisions made by the EPA scientists and risk managers. The EPA collects incident reports on human, domestic animal, and ecological injury. The FIFRA section 6(a)(2) rule requires the pesticide registrant (generally, the company or other entity that wishes to market the pesticide, hereafter registrant) to submit such data to the EPA. The EPA’s ecological incident category includes injuries to aquatic (fish), terrestrial (wildlife), other non-target organisms (ONT, e.g., invertebrates) and plants. Our document focuses on the fish and wildlife ecological incidents that are submitted by registrants. We critique the application of the FIFRA section 6(a)(2) rule that controls the quality and quantity of ecological incident data that the EPA receives from registrants. We conclude that the section 6(a)(2) provisions can impede the transfer of ecological incident data from registrant to the EPA. Consequently, detailed data for many fish and wildlife incidents may never reach the EPA, and policies and decisions may be formulated in the absence of these data.

Buffalo Environmental Law Journal↗
USGS2023

Isothermal recombinant polymerase amplification and CRIPSR (CAS12A) assay detection of Renibacterium salmoninarum as an example for wildlife pathogen detection in environmental DNA samples

Improving rapid detection methods for pathogens is important for research as we collectively aim to improve the health of ecosystems globally. In the northern hemisphere, the success of salmon ( Oncorhynchus spp.) populations is vitally important to the larger marine, aquatic, and terrestrial ecosystems they inhabit. This has led to managers cultivating salmon in hatcheries and aquaculture to bolster their populations, but young salmon face many challenges, including diseases such as bacterial kidney disease (BKD). Early detection of the BKD causative agent, Renibacterium salmoninarum , is useful for managers to avoid outbreaks in hatcheries and aquaculture stocks to enable rapid treatment with targeted antibiotics. Isothermal amplification and CRIPSR-Cas12a systems may enable sensitive, relatively rapid, detection of target DNA molecules from environmental samples compared to quantitative PCR (qPCR) and culture methods. We used these technologies to develop a sensitive and specific rapid assay to detect R. salmoninarum from water samples using isothermal recombinase polymerase amplification (RPA) and an AsCas12a RNA-guided nuclease detection. The assay was specific to R. salmoninarum (0/10 co-occurring or closely related bacteria detected) and sensitive to 0.0128 pg/µL of DNA (approximately 20–40 copies/µL) within 10 min of Cas activity. This assay successfully detected R. salmoninarum environmental DNA in 14/20 water samples from hatcheries with known quantification for the pathogen via previous qPCR (70% of qPCR-positive samples). The RPA-CRISPR/AsCas12a assay had a limit of detection (LOD) of >10 copies/µL in the hatchery water samples and stochastic detection below 10 copies/µL, similar to but slightly higher than the qPCR assay. This LOD enables 37 C isothermal detection, potentially in the field, of biologically relevant levels of R. salmoninarum in water. Further research is needed to develop easy-to-use, cost-effective, sensitive RPA/CRISPR-AsCas12a assays for rapidly detecting low concentrations of wildlife pathogens in environmental samples.

Journal of Wildlife Diseases↗
USGS2019

Managing for multiple species: Greater sage‐grouse and sagebrush songbirds

Human activity has altered 33–50% of Earth's surface, including temperate grasslands and sagebrush rangelands, resulting in a loss of biodiversity. By promoting habitat for sensitive or wide‐ranging species, less exigent species may be protected in an umbrella effect. The greater sage‐grouse ( Centrocercus urophasianus ; sage‐grouse) has been proposed as an umbrella for other sagebrush‐obligate species because it has an extensive range that overlaps with many other species, it is sensitive to anthropogenic activity, it requires resources over large landscapes, and its habitat needs are known. The efficacy of the umbrella concept, however, is often assumed and rarely tested. Therefore, we surveyed sage‐grouse pellet occurrence and sagebrush‐associated songbird abundance in northwest Colorado, USA, to determine the amount of habitat overlap between sage‐grouse and 4 songbirds (Brewer's sparrow [ Spizella breweri ], sage thrasher [ Oreoscoptes montanus ], sagebrush sparrow [ Artemisiospiza nevadensis ]), and green‐tailed towhee [ Pipilo chlorurus ]). During May and June 2013–2015, we conducted standard point count breeding surveys for songbirds and counted sage‐grouse pellets within 300 10‐m radius plots. We modeled songbird abundance and sage‐grouse pellet occurrence with multi‐scaled environmental features, such as sagebrush cover and bare ground. To evaluate sage‐grouse as an umbrella for sagebrush‐associated passerines, we determined the correlation between probability of sage‐grouse pellet occurrence and model‐predicted songbird densities per sampling plot. We then classified the sage‐grouse probability of occurrence as high (probability >0.5) and low (probability ≤0.5) and mapped model‐predicted surfaces for each species in our study area. We determined average songbird density in areas of high and low probability of sage‐grouse occurrence. Sagebrush cover at intermediate scales was an important predictor for all species, and ground cover was important for all species except sage thrashers. Areas with a higher probability of sage‐grouse occurrence also contained higher densities of Brewer's sparrows, green‐tailed towhees, and sage thrashers, but predicted sagebrush sparrow densities were lower in these areas. In northwest Colorado, sage‐grouse may be an effective umbrella for Brewer's sparrows, green‐tailed towhees, and sage thrashers, but sage‐grouse habitat does not appear to capture areas that support high sagebrush sparrow densities. A multi‐species focus may be the best management and conservation strategy for several species of concern, especially those with conflicting habitat requirements.

Colorado↗
USGS2015

Sources of high-chloride water and managed aquifer recharge in an alluvial aquifer in California, USA

As a result of pumping in excess of recharge, water levels in alluvial aquifers within the Eastern San Joaquin Groundwater Subbasin, 130 km east of San Francisco (California, USA), declined below sea level in the early 1950s and have remained so to the present. Chloride concentrations in some wells increased during that time and exceeded the US Environmental Protection Agency’s secondary maximum contaminant level of 250 mg/L, resulting in removal of some wells from service. Sources of high-chloride water include irrigation return in 16 % of sampled wells and water from delta sediments and deeper groundwater in 50 % of sampled wells. Chloride concentrations resulting from irrigation return commonly did not exceed 100 mg/L, although nitrate concentrations were as high as 25 mg/L as nitrogen. Chloride concentrations ranged from less than 100–2,050 mg/L in wells affected by water from delta sediments and deeper groundwater. Sequential electromagnetic logs show movement of high-chloride water from delta sediments to pumping wells through permeable interconnected aquifer layers. δD and δ18O data show most groundwater originated as recharge along the front of the Sierra Nevada, but tritium and carbon-14 data suggest recharge rates in this area are low and have decreased over recent geologic time. Managed aquifer recharge at two sites show differences in water-level responses to recharge and in the physical movement of recharged water with depth related to subsurface geology. Well-bore flow logs also show rapid movement of water from recharge sites through permeable interconnected aquifer layers to pumping wells.

California↗
USGS2023

Integrated rangeland fire management strategy actionable science plan completion assessment— Climate and weather topic, 2015–20

Loss and degradation of sagebrush ( Artemisia spp.) rangelands due to an accelerated invasive annual grass-wildfire cycle and other stressors are significant management, conservation, and economic issues in the western U.S. These sagebrush rangelands comprise a unique biome spanning 11 states, support over 350 wildlife species, and provide important ecosystem services that include stabilizing the economies of western communities. Impacts to sagebrush ecosystem processes over large areas due to the annual grass-wildfire cycle necessitated the development of a coordinated, science-based strategy for improving efforts to achieve long-term protection, conservation, and restoration of sagebrush rangelands, which was framed in 2015 under the Integrated Rangeland Fire Management Strategy (IRFMS). Central to this effort was the development of an Actionable Science Plan (Plan) that identified 37 priority science needs (hereinafter, “Needs”) for informing the actions proposed under the five topics (Fire, Invasives, Restoration, Sagebrush and Sage-Grouse ( Centrocercus urophasianus ), Climate and Weather) that were part of the collective focus of the IRFMS. Notable keys to this effort were identification of the Needs co-produced by managers and researchers, and a focus on resulting science being “actionable.” Substantial investments aimed at fulfilling the Needs identified in the Plan have been made since its release in 2016. While the state of the science has advanced considerably, the extent to which knowledge gaps remain relative to identified Needs is relatively unknown. Moreover, new Needs have likely emerged since the original strategy as results from actionable science reveal new questions and possible (yet untested) solutions. A quantifiable assessment of the progress made on the original science Needs can identify unresolved gaps and new information that can help inform prioritization of future research efforts. This report details a systematic literature review that evaluated how well peer-reviewed journal articles and formal technical reports published between January 1, 2015, and December 31, 2020, addressed four Needs identified under the Climate and Weather topic in the Plan. The topic outlined research Needs broadly focused on understanding the potential effects of climate change on vegetative resilience to inform restoration of sagebrush rangelands. We established the level of progress towards addressing each Need following a standardized set of criteria, and developed summaries detailing how research objectives nested within Needs identified in the Plan (hereinafter, “Next Steps”) were either addressed well, partially addressed or remain outstanding (that is, addressed poorly) in the literature through 2020. Our searches resulted in the inclusion of 92 science products that at least partially addressed a Need identified in the Climate and Weather topic. The Needs that were well and partially addressed included: studies of the complex set of climatic relationships that influence sagebrush rangeland restoration and seeding success; the identification of seed collection areas across the range of environmental variability inhabited by target restoration species; and develop predictive models to assess targeted restoration species’ responses to mid-century climatic conditions. The Need addressed poorly was the identification of native plant species, genotypes and ecotypes, and seed mixes that may be resilient to a changing climate. The information provided in this assessment will assist updating the Plan, and can inform updates of other relevant science planning documents as needed.

Open-File Report↗
USGS2008

Managing visitor impacts in parks: A multi-method study of the effectiveness of alternative management practices

How can recreation use be managed to control associated environmental impacts? What management practices are most effective and why? This study explored these and related questions through a series of experimental ?treatments? and associated ?controls? at the summit of Cadillac Mountain in Acadia National Park, a heavily used and environmentally fragile area. The treatments included five management practices designed to keep visitors on maintained trails, and these practices ranged from ?indirect? (information/education) to ?direct? (a fence bordering the trail). Research methods included unobtrusive observation of visitors to determine the percentage of visitors who walked off-trail and a follow-up visitor survey to explore why management practices did or didn?t work. All of the management practices reduced the percentage of visitors who walked off-trail. More aggressive applications of indirect practices were more effective than less aggressive applications, and the direct management practice of fencing was the most effective of all. None of the indirect management practices reduced walking off-trail to a degree that is likely to control damage to soil and vegetation at the study site. Study findings suggest that an integrated suite of direct and indirect management practices be implemented on Cadillac Mountain (and other, similar sites) that includes a) a regulation requiring visitors to stay on the maintained trail, b) enforcement of this regulation as needed, c) unobtrusive fencing along the margins of the trail, d) redesign of the trail to extend it, widen it in key places, and provide short spur trails to key ?photo points?, and e) an aggressive information/education program to inform visitors of the regulation to stay on the trail and the reasons for it. These recommendations are a manifestation of what may be an emerging principle of park and outdoor recreation management: intensive use requires intensive management.

Journal of Park and Recreation Administration↗
USGS2017

Environmental conditions and prey-switching by a seabird predator impact juvenile salmon survival

Due to spatio-temporal variability of lower trophic-level productivity along the California Current Ecosystem (CCE), predators must be capable of switching prey or foraging areas in response to changes in environmental conditions and available forage. The Gulf of the Farallones in central California represents a biodiversity hotspot and contains the largest common murre ( Uria aalge ) colonies along the CCE. During spring, one of the West Coast's most important Chinook salmon ( Oncorhynchus tshawytscha ) populations out-migrates into the Gulf of the Farallones. We quantify the effect of predation on juvenile Chinook salmon associated with ecosystem-level variability by integrating long-term time series of environmental conditions (upwelling, river discharge), forage species abundance within central CCE, and population size, at-sea distribution, and diet of the common murre. Our results demonstrate common murres typically forage in the vicinity of their offshore breeding sites, but in years in which their primary prey, pelagic young-of-year rockfish ( Sebastes spp.), are less available they forage for adult northern anchovies ( Engraulis mordax ) nearshore . Incidentally, while foraging inshore, common murre consumption of out-migrating juvenile Chinook salmon, which are collocated with northern anchovy, increases and population survival of the salmon is significantly reduced. Results support earlier findings that show timing and strength of upwelling , and the resultant forage fish assemblage, is related to Chinook salmon recruitment variability in the CCE, but we extend those results by demonstrating the significance of top-down impacts associated with these bottom-up dynamics. Our results demonstrate the complexity of ecosystem interactions and impacts between higher trophic-level predators and their prey, complexities necessary to quantify in order to parameterize ecosystem models and evaluate likely outcomes of ecosystem management options.

California↗
USGS2000

Use of isotopically labeled fertilizer to trace nitrogen fertilizer contributions to surface, soil, and ground water

The fate and transport of a single N fertilizer application through plants, soil, runoff, and the unsaturated and saturated zones was determined for four years at a field site under continuous corn (Zea mays L.) management. Claypan soils, which underlie the site, were hypothesized to restrict the movement of agrichemicals from the soil surface to ground water. However, N fertilizer moved rapidly through preferential flow paths in the soil and into the underlying glacial till aquifer. Most N transport occurred during the fall and winter when crops were not available to use excess N. Forty months after application, 33 percent of the fertilizer had been removed by grain harvests, 30 percent had been transpired to the atmosphere, and 33 percent had migrated to ground water. Although runoff volumes were 50 percent greater than infiltration, less than 2 percent of the fertilizer was lost to runoff. Small measured denitrification rates and large measured dissolved oxygen concentrations in ground water favor the long-term stability of NO3-1 in ground water. Successive fertilizer applications, in areas that lack the ability to moderate N concentrations through consumptive N reactions, risk the potential of N-saturated ecosystems.

Journal of Environmental Hydrology↗
USGS2006

Multiphase, multicomponent parameter estimation for liquid and vapor fluxes in deep arid systems using hydrologic data and natural environmental tracers

Multiphase, multicomponent numerical models of long-term unsaturated-zone liquid and vapor movement were created for a thick alluvial basin at the Nevada Test Site to predict present-day liquid and vapor fluxes. The numerical models are based on recently developed conceptual models of unsaturated-zone moisture movement in thick alluvium that explain present-day water potential and tracer profiles in terms of major climate and vegetation transitions that have occurred during the past 10 000 yr or more. The numerical models were calibrated using borehole hydrologic and environmental tracer data available from a low-level radioactive waste management site located in a former nuclear weapons testing area. The environmental tracer data used in the model calibration includes tracers that migrate in both the liquid and vapor phases (δD, δ 18 O) and tracers that migrate solely as dissolved solutes (Cl), thus enabling the estimation of some gas-phase as well as liquid-phase transport parameters. Parameter uncertainties and correlations identified during model calibration were used to generate parameter combinations for a set of Monte Carlo simulations to more fully characterize the uncertainty in liquid and vapor fluxes. The calculated background liquid and vapor fluxes decrease as the estimated time since the transition to the present-day arid climate increases. However, on the whole, the estimated fluxes display relatively little variability because correlations among parameters tend to create parameter sets for which changes in some parameters offset the effects of others in the set. Independent estimates on the timing since the climate transition established from packrat midden data were essential for constraining the model calibration results. The study demonstrates the utility of environmental tracer data in developing numerical models of liquid- and gas-phase moisture movement and the importance of considering parameter correlations when using Monte Carlo analysis to characterize the uncertainty in moisture fluxes.

Vadose Zone Journal↗
USGS2018

Identifying and eliminating sources of recreational water quality degradation along an urban coast

Restoration of highly degraded urban coastal waters often requires large-scale, complex projects, but in the interim, smaller-scale efforts can provide immediate improvements to water quality conditions for visitor use. We examined short-term efforts to improve recreational water quality near the Grand Calumet River (GC) in the Laurentian Great Lakes. Identified as an Area of Concern (AOC) by the International Joint Commission, the GC has experienced years of industrial and municipal waste discharges, and as a result, coastal beaches have some of the highest rates of beach closings (>70%) in the United States. Project objectives were to identify sources of microbial contamination and to evaluate a short-term management solution to decrease beach closings: during 2015 (partial) and 2016 (season-long), canines were used to deter gull presence. Water samples were analyzed for Escherichia coli in 2015 and 2016, and fecal sources were evaluated using microbial source tracking markers (2015): human ( Bacteroides HF183, Methanobrevibacter nifH ), gull (Gull2), and dog (DogBact). Hydrometeorological conditions were simultaneously measured. Results indicated that human, gull, and canine fecal sources were present, with gulls being the dominant source. Escherichia coli densities were highly correlated with number of gulls present, Gull2 marker, and turbidity. Gull deterrence decreased E. coli and Gull2 marker detection during 2015, but numbers rebounded after program completion. The full-season program in 2016 resulted in lower E. coli densities and fewer beach closings. Large-scale restoration efforts are underway at this location, but short-term, small-scale projects can be useful for reducing beach closings and restoring ecosystem services.

Indiana↗
USGS2014

Long-term effects of seeding after wildfire on vegetation in Great Basin shrubland ecosystems

1. Invasive annual grasses alter fire regimes in shrubland ecosystems of the western USA, threatening ecosystem function and fragmenting habitats necessary for shrub-obligate species such as greater sage-grouse. Post-fire stabilization and rehabilitation treatments have been administered to stabilize soils, reduce invasive species spread and restore or establish sustainable ecosystems in which native species are well represented. Long-term effectiveness of these treatments has rarely been evaluated. 2. We studied vegetation at 88 sites where aerial or drill seeding was implemented following fires between 1990 and 2003 in Great Basin (USA) shrublands. We examined sites on loamy soils that burned only once since 1970 to eliminate confounding effects of recurrent fire and to assess soils most conducive to establishment of seeded species. We evaluated whether seeding provided greater cover of perennial seeded species than burned–unseeded and unburned–unseeded sites, while also accounting for environmental variation. 3. Post-fire seeding of native perennial grasses generally did not increase cover relative to burned–unseeded areas. Native perennial grass cover did, however, increase after drill seeding when competitive non-natives were not included in mixes. Seeding non-native perennial grasses and the shrub Bassia prostrata resulted in more vegetative cover in aerial and drill seeding, with non-native perennial grass cover increasing with annual precipitation. Seeding native shrubs, particularly Artemisia tridentata , did not increase shrub cover or density in burned areas. Cover of undesirable, non-native annual grasses was lower in drill seeded relative to unseeded areas, but only at higher elevations. 4. Synthesis and applications. Management objectives are more likely to be met in high-elevation or precipitation locations where establishment of perennial grasses occurred. On lower and drier sites, management objectives are unlikely to be met with seeding alone. Intensive restoration methods such as invasive plant control and/or repeated sowings after establishment failures due to weather may be required in subsequent years. Managers might consider using native-only seed mixtures when establishment of native perennial grasses is the goal. Post-fire rehabilitation provides a land treatment example where long-term monitoring can inform adaptive management decisions to meet future objectives, particularly in arid landscapes where recovery is slow.

Great Basin↗
USGS2026

Assessing future hydrologic extremes using an integrated hydrology and river operations model in the Russian River watershed

Study region The Russian River watershed, situated in coastal, northern California, experiences hydrologic extremes, including periodic droughts and flooding. Water managers are working to maintain sustainable water supplies and environmental flows, while mitigating flood risks. Study focus This paper introduces an integrated hydrology and river operations model for the Russian River watershed. This model is distinct from models in previous studies because it represents surface-groundwater interactions and uses climate forcings to estimate dynamic water use demands that are superimposed onto both reservoir operations and water supply constraints. The model was used to examine three historical (1990–2015) and eight future (2016–2099) water use and climate change scenarios. New hydrological insights for the region The direct connection between streams and aquifers facilitated both annual aquifer replenishment by high winter streamflows and streamflow depletion by groundwater wells (19 % of pumped groundwater in alluvial aquifers from stream leakage) during critical low flow periods. Simulated streamflow changes included 59 % longer and 54 % more severe streamflow droughts, 26 % lower seasonal low streamflows, and up to 125 % higher peak streamflows, averaged over future climate and water use scenarios, suggesting increased future flood and water availability risks. Results showed the importance of reservoir operations for mitigating the impacts of increased hydroclimatic volatility, despite a decrease in reservoir reliability at Lake Mendocino, suggesting that reservoir management may be used to decrease future risks.

California↗
USGS2018

Great Lakes coastal fish habitat classification and assessment

Basin-scale assessment of fish habitat in Great Lakes coastal ecosystems would increase our ability to prioritize fish habitat management and restoration actions. As a first step in this direction, we identified key habitat factors associated with highest probability of occurrence for several societally and ecologically important coastal fish species as well as community metrics, using data from the Great Lakes Aquatic Habitat Framework (GLAHF), Great Lakes Environmental Indicators (GLEI) and Coastal Wetland Monitoring Program (CWMP). Secondly, we assessed whether species-specific habitat was threatened by watershed-level anthropogenic stressors. In the southern Great Lakes, key habitat factors for determining presence/absence of several species of coastal fish were chlorophyll concentrations, turbidity, and wave height, whereas in the northern ecoprovince temperature was the major habitat driver for most of the species modeled. Habitat factors best explaining fish richness and diversity were bottom slope and chlorophyll a . These models could likely be further improved with addition of high-resolution submerged macrophytecomplexity data which are currently unavailable at the basin-wide scale. Proportion of invasive species was correlated primarily with increasing maximum observed inorganic turbidity and chlorophyll a . We also demonstrate that preferred habitat for several coastal species and high-diversity areas overlap with areas of high watershed stress. Great Lakes coastal wetland fish are a large contributor to ecosystem services as well as commercial and recreational fishery harvest, and scalable basin-wide habitat models developed in this study may be useful for informing management actions targeting specific species or overall coastal fish biodiversity.

Great Lakes↗
USGS1993

Environmental contaminants in bald eagles in the Columbia River Estuary

Eggs, blood, and carcasses of bald eagles ( Haliaeetus leucocephalus ) and fish were collected and breeding success of eagles was monitored in the Columbia River estuary, 1980-87, to determine if contaminants were having an effect on productivity. High levels of dichloro diphenyl dichloroethylene (DDE), polychlorinated biphenyls (PCB's), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were found in eggs, blood from adults, and 2 eagle carcasses. Detectable levels of DDE and PCB's were found in blood of nestlings indicating they were exposed to these contaminants early in life. Increasing concentrations of DDE and PCB's with age also indicated accumulation of these contaminants. Adult eagles also had higher levels of mercury (Hg) in blood than subadults or young indicating accumulation with age. The high levels of DDE and PCB's were associated with eggshell thinning (x̄ = 10%) and with productivity (x̄ = 0.56 young/occupied site) that was lower than that of healthy populations (i.e., ≥1.00 young/occupied site). DDE and PCB's had a deleterious effect on reproduction of bald eagles in the estuary. The role dioxins play in eagle reproduction remains unclear, but concentrations in eagle eggs were similar to those in laboratory studies on other species where dioxins adversely affected hatchability of eggs. Probable sources of these contaminants include dredged river sediments and hydroelectric dams, and the proper management of each may reduce the amount of contaminants released into the Columbia River estuary.

Oregon, Washington↗