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At least 1,675 records · Page 93Linked to original sources
USGS2019

Supporting the development and use of native plant materials for restoration on the Colorado Plateau (Fiscal Year 18 Report)

Introduction A primary focus of the Colorado Plateau Native Plant Program (CPNPP) is to identify and develop appropriate native plant materials (NPMs) for current and future restoration projects. Multiple efforts have characterized the myriad challenges inherent in providing appropriate seed resources to enable effective, widespread restoration and identified a broad suite of research activities to provide the information necessary to overcome those challenges (e.g., Plant Conservation Alliance 2015; Breed et al. 2018). Many of the most complex information needs relate to identifying the appropriate plant species and populations that can successfully establish in dryland environments, like the Colorado Plateau, where low and highly variable precipitation is standard. Providing this information requires synergistic research efforts in which results from earlier investigations inform the design of subsequent investigations. Southwest Biological Science Center’s (SBSC’s) research activities in FY18 followed the FY18 Statement of Work (“Research supporting native plant materials development for the Colorado Plateau Native Plant Program, FY18”) to support a research framework that is continually adapting based on the needs of the restoration community and results from previous investigations; the long-term research framework is now outlined in the 2019-2023 5-Year Research Strategy (discussed below; hereafter referred to as the 5-Year Research Strategy). This research framework provides support for the National Seed Strategy for Rehabilitation and Restoration (Plant Conservation Alliance, 2015), Department of Interior Secretarial Order #3347 (Conservation Stewardship and Outdoor Recreation), and Bureau of Land Management Leadership Priority #1 (Create a conservation stewardship legacy second only to Teddy Roosevelt). The overall focus of activities in FY18 centered on landscape genetics and planning for common garden and other research projects. These activities were supported by two biological technicians that were hired and trained by Dr. Rob Massatti and Dr. Daniel Winkler. Many of the field-related activities, including plant trait measurement and seed/tissue collecting, were assigned to these technicians, which freed Dr. Massatti to work on other research objectives, including the time-consuming activities of processing and analyzing genetic data. A major challenge to field work in FY18 was the drought conditions that pervaded the Plateau during the spring field season. Due to low winter and spring precipitation, many plant communities did not green up in the spring, which prevented the biological technicians from collecting plant trait data, tissues samples, and seeds in many areas. To cope with the dry conditions, the technicians searched sites across a wider range of environmental space and considered a broader suite of species from which to collect data (i.e., species that may be included in research projects in future years). Monsoonal precipitation starting in July supported a late summer/fall field season and allowed the technicians to follow a more normal work plan. While Dr. Massatti was the only scientist supported by the SBSC-CPNPP agreement in FY18, other scientists, including Drs. John Bradford, Seth Munson, Mike Duniway, Sasha Reed, Daniel Winkler, and Jayne Belnap, spent a considerable amount of time discussing individual projects and the newly developed 5-Year Research Strategy. Some of these discussions resulted in a publication by Dr. Winkler, in addition to a large group of researchers, practitioners, and others who work on the Colorado Plateau, concerning the restoration challenges facing the Plateau into the future and the types of efforts that may support successful restoration (Winkler et al., 2018).

Colorado↗
USGS2023

Successful eradication of invasive American bullfrogs leads to coextirpation of emerging pathogens

Interventions of the host–pathogen dynamics provide strong tests of relationships, yet they are still rarely applied across multiple populations. After American bullfrogs ( Rana catesbeiana ) invaded a wildlife refuge where federally threatened Chiricahua leopard frogs ( R. chiricahuensis ) were reintroduced 12 years prior, managers launched a landscape-scale eradication effort to help ensure continued recovery of the native species. We used a before-after-control-impact design and environmental DNA sampling of 19 eradication sites and 18 control sites between fall 2016 and winter 2020–2021 to measure community-level responses to bullfrog eradication, including for two pathogens. Dynamic occupancy models revealed successful eradication from 94% of treatment sites. Native amphibians did not respond to bullfrog eradication, but the pathogens amphibian chytrid fungus ( Batrachochytrium dendrobatidis ) and ranaviruses were coextirpated with bullfrogs. Our spatially replicated experimental approach provides strong evidence that management of invasive species can simultaneously reduce predation and disease risk for imperiled species.

Arizona↗
USGS2020

A novel quantitative framework for riverscape genetics

Riverscape genetics, which applies concepts in landscape genetics to riverine ecosystems, lack appropriate quantitative methods that address the spatial autocorrelation structure of linear stream networks and account for bidirectional geneflow. To address these challenges, we present a general framework for the design and analysis of riverscape genetic studies. Our framework starts with the estimation of pairwise genetic distance at sample sites and the development of a spatially structured ecological network (SSEN) on which riverscape covariates are measured. We then introduce the novel bidirectional geneflow in riverscapes (BGR) model that uses principles of isolation-by-resistance to quantify the effects of environmental covariates on genetic connectivity, with spatial covariance defined using simultaneous autoregressive models on the SSEN and the generalized Wishart distribution to model pairwise distance matrices arising through a random walk model of geneflow. We highlight the utility of this framework in an analysis of riverscape genetics for brook trout ( Salvelinus fontinalis ) in north central Pennsylvania, USA. Using the fixation index ( F ST ) as the measure of genetic distance, we estimated the effects of 12 riverscape covariates on geneflow by evaluating the relative support of eight competing BGR models. We then compared the performance of the top-ranked BGR model to results obtained from comparable analyses using multiple regression on distance matrices (MRM) and the program STRUCTURE. We found that the BGR model had more power to detect covariate effects, particularly for variables that were only partial barriers to geneflow and/or uncommon in the riverscape, making it more informative for assessing patterns of population connectivity and identifying threats to species conservation. This case study highlights the utility of our modeling framework over other quantitative methods in riverscape genetics, particularly the ability to rigorously test hypotheses about factors that influence geneflow and probabilistically estimate the effect of riverscape covariates, including stream flow direction. This framework is flexible across taxa and riverine networks, is easily executable, and provides intuitive results that can be used to investigate the likely outcomes of current and future management scenarios.

Ecological Applications↗
USGS2026

Watershed Continuum Monitoring Approach: Combining multiple water quality patterns along stream and river flowpaths to track sources, pathways, and processing of pollutants

There is a growing need to improve and expand water quality monitoring approaches to more accurately track the sources, fate, and transport of multiple chemicals and pollutants holistically and quantify the effects of best management practices (BMPs) at the watershed scale. An overarching question raised by scientists, environmental managers, and the general public is: how far can water quality impacts from disturbances or benefits from watershed management and restoration propagate along stream and river flowpaths? Many studies using the classic watershed approach focus on analyzing changes in water quality over time at one or a few sampling stations, whereas theories such as the River Continuum Concept focus on predicting shifts in energy sources and biological communities along rivers but have not been directly applied to water quality. We propose to merge these concepts to create a Watershed Continuum Monitoring Approach (WCMA) that combines both spatial and temporal monitoring in order to better detect and quantify trends and transitions in multiple water quality indicators along flowpaths. Specifically, an array of multiple water quality indicators are analyzed at multiple downstream points along a watershed flowpath over time. These multiple water quality indicators are analyzed together for making comparisons to infer hydrological, biological, and geochemical processes controlling sources, transport, and attenuation of pollutants ( e.g. , analagous to stream tracer studies at the watershed scale). The WCMA leverages the natural expansion of watershed areas along a flowpath, which reflect transitions in land use, land cover, and environmental management across spatial and temporal dimensions for making direct comparisons across different stream reaches and spatial trend analysis. WCMA facilitates monitoring of multiple water quality indicators together, and identifcation of hot spots in sources and attenuation of pollutants or mixtures of pollutants. We illustrate practical applications of the WCMA to analyze water quality trends, transitions, and tradeoffs ( i.e. , a tradeoff occurs when one pollutant is reduced but another is directly or indirectly increased downstream). We explore case studies that quantify: (1) downstream reductions in concentrations of multiple pollutants along a stream flowing to a major drinking water source due to engineered and nature-based solutions, (2) downstream reductions in multiple pollutants and water quality tradeoffs along streams experiencing stormwater BMPs and stream restoration, (3) comparisons in downstream reductions of multiple pollutants and nutrient uptake along streams draining into major drinking water sources based on types of stream restoration, (4) comparisons of downstream pollutant reductions along streams experiencing riparian forest conservation vs. stream restoration, and (5) mapping and visualizing hot spots of increasing water quality problems such as hypoxia, contaminant mobilization, and freshwater salinization that extend downstream to tidal rivers of the Chesapeake Bay. We explore future applications of WCMA for tracking decreasing trends in salinity, E. coli , and other pollutants of emerging concern. WCMA can holistically inform progress towards achieving multiple water quality goals and also be used as a screening tool for selecting monitoring sites and targeting management in strategic locations. Overall, WCMA enables the simultaneous quantification and comparison of sources and transport and attenuation rates for different chemicals and pollutants across a broader range of watershed sizes and flowpath lengths, which is critical for understanding ecological, hydrological, geochemical, and biogeochemical processes along human-impacted streams and rivers.

Ecological Engineering↗
USGS2010

Assessing allowable take of migratory birds

Legal removal of migratory birds from the wild occurs for several reasons, including subsistence, sport harvest, damage control, and the pet trade. We argue that harvest theory provides the basis for assessing the impact of authorized take, advance a simplified rendering of harvest theory known as potential biological removal as a useful starting point for assessing take, and demonstrate this approach with a case study of depredation control of black vultures (Coragyps atratus) in Virginia, USA. Based on data from the North American Breeding Bird Survey and other sources, we estimated that the black vulture population in Virginia was 91,190 (95% credible interval = 44,520?212,100) in 2006. Using a simple population model and available estimates of life-history parameters, we estimated the intrinsic rate of growth (rmax) to be in the range 7?14%, with 10.6% a plausible point estimate. For a take program to seek an equilibrium population size on the conservative side of the yield curve, the rate of take needs to be less than that which achieves a maximum sustained yield (0.5 x rmax). Based on the point estimate for rmax and using the lower 60% credible interval for population size to account for uncertainty, these conditions would be met if the take of black vultures in Virginia in 2006 was < 3,533 birds. Based on regular monitoring data, allowable harvest should be adjusted annually to reflect changes in population size. To initiate discussion about how this assessment framework could be related to the laws and regulations that govern authorization of such take, we suggest that the Migratory Bird Treaty Act requires only that take of native migratory birds be sustainable in the long-term, that is, sustained harvest rate should be < rmax. Further, the ratio of desired harvest rate to 0.5 x rmax may be a useful metric for ascertaining the applicability of specific requirements of the National Environmental Protection Act.

Journal of Wildlife Management↗
USGS2024

Estimating multivariate ecological variables at high spatial resolution using a cost-effective matching algorithm

Simulation models are valuable tools for estimating ecosystem response to environmental conditions and are particularly relevant for investigating climate change impacts. However, because of high computational requirements, models are often applied over a coarse grid of points or for representative locations. Spatial interpolation of model output can be necessary to guide decision-making, yet interpolation is not straightforward because the interpolated values must maintain the covariance structure among variables. We present methods for two key steps for utilizing limited simulations to generate detailed maps of multivariate and time series output. First, we present a method to select an optimal set of simulation sites that maximize the area represented for a given number of sites. Then, we introduce a multivariate matching approach to interpolate simulation results to detailed maps for the represented area. This approach links simulation output to environmentally analogous matched sites according to user-defined criteria. We demonstrate the methods with case studies using output from (1) an individual-based plant simulation model to illustrate site selection, and (2) an ecosystem water balance simulation model to illustrate interpolation. For the site selection case study, we identified 200 simulation sites that represented 96% of a large study area (1.12 × 10 6 km 2 ) at a ~1-km resolution. For the interpolation case study, we generated ~1-km resolution maps across 4.38 × 10 6 km 2 of drylands in North America from a 10 × 10 km grid of simulated sites. Estimates of interpolation errors using cross validation were low (less than 10% of the range of each variable). Our point selection and interpolation methods, which are available as an easy-to-use R package, provide a means of cost-effectively generating detailed maps of expensive, complex simulation output (e.g., multivariate and time series) at scales relevant for local conservation planning. Our methods are flexible and allow the user to identify relevant matching criteria to balance interpolation uncertainty with areal coverage to enhance inference and decision-making at management-relevant scales across large areas.

Ecosphere↗
USGS2015

Management applications of discontinuity theory

Human impacts on the environment are multifaceted and can occur across distinct spatiotemporal scales. Ecological responses to environmental change are therefore difficult to predict, and entail large degrees of uncertainty. Such uncertainty requires robust tools for management to sustain ecosystem goods and services and maintain resilient ecosystems. We propose an approach based on discontinuity theory that accounts for patterns and processes at distinct spatial and temporal scales, an inherent property of ecological systems. Discontinuity theory has not been applied in natural resource management and could therefore improve ecosystem management because it explicitly accounts for ecological complexity. Synthesis and applications . We highlight the application of discontinuity approaches for meeting management goals. Specifically, discontinuity approaches have significant potential to measure and thus understand the resilience of ecosystems, to objectively identify critical scales of space and time in ecological systems at which human impact might be most severe, to provide warning indicators of regime change, to help predict and understand biological invasions and extinctions and to focus monitoring efforts. Discontinuity theory can complement current approaches, providing a broader paradigm for ecological management and conservation.

Journal of Applied Ecology↗
USGS2002

Relation of Environmental characteristics to the composition of aquatic assemblages along a gradient of urban land use in New Jersey, 1996-98

Community data from 36 watersheds were used to evaluate the response of fish, invertebrate, and algal assemblages in New Jersey streams to environmental characteristics along a gradient of urban land use that ranged from 3 to 96 percent. Aquatic assemblages were sampled at 36 sites during 1996-98, and more than 400 environmental attributes at multiple spatial scales were summarized. Data matrices were reduced to 43, 170, and 103 species of fish, invertebrates, and algae, respectively, by means of a predetermined joint frequency and relative abundance approach. White sucker (Catostomus commersoni) and Tessellated darter (Etheostoma olmstedi) were the most abundant fishes, accounting for more than 20 and 17 percent, respectively, of the mean abundance. Net-spinning caddisflies (Hydropsychidae) were the most commonly occurring benthic invertebrates and were found at all but one of the 36 sampling sites. Blue-green (for example, Calothrix sp. and Oscillatoria sp.) and green (for example, Protoderma viride) algae were the most widely distrib-uted algae; however, more than 81 percent of the algal taxa collected were diatoms. Principal-component and correlation analyses were used to reduce the dimensionality of the environmental data. Multiple linear regression analysis of extracted ordination axes then was used to develop models that expressed effects of increasing urban land use on the structure of aquatic assemblages. Significant environmental variables identified by using multiple linear regression analysis then were included in a direct gradient analysis. Partial canonical correspondence analysis of relativized abundance data was used to restrict further the effects of residual natural variability, and to identify relations among the environmental variables and the structure of fish, invertebrate, and algal assemblages along an urban land-use gradient. Results of this approach, combined with the results of the multiple linear regression analyses, were used to identify human population density (311-37,594 persons/km2), amount and type of impervious surface cover (0.12-1,350 km2), nutrient concentrations (for example, 0.01-0.29 mg/L of phosphorus), hydrologic instability (for example, 100-8,955 ft3/s for 2-year peak flow), the amount of forest and wetlands in a basin (0.01-6.25 km2), and substrate quality (0-87 percent cobble substrate) as variables that are highly correlated with aquatic-assemblage structure. Species distributions in ordination space clearly indicate that tolerant species are more abundant in the streams impaired by urbanization and sensitive taxa are more closely associated with the least impaired basins. The distinct differences in aquatic assemblages along the urban land-use gradient demonstrate the deleterious effects of urbanization on assemblage structure and indicate that conserving landscape attributes that mitigate anthropogenic influences (for example, stormwater-management practices emphasizing infiltration and preservation of existing forests, wetlands, and riparian corridors) will help to maintain the relative abundance of sensitive taxa. Complementary multiple linear regression models indicate that aquatic community indices were correlated with many of the anthropogenic factors that were found to be significant along the urban land-use gradient. These indices appear to be effective in differentiating the moderately and severely impaired streams from the minimally impaired streams. Evaluation of disturbance thresholds for aquatic assemblages indicates that moderate to severe impairment is detectable in New Jersey streams when impervious surface cover in the drainage basin reaches approximately 18 percent.

Water-Resources Investigations Report↗
USGS1985

Optimal management strategies in variable environments: Stochastic optimal control methods

Dynamic optimization was used to investigate the optimal defoliation of salt desert shrubs in north-western Utah. Management was formulated in the context of optimal stochastic control theory, with objective functions composed of discounted or time-averaged biomass yields. Climatic variability and community patterns of salt desert shrublands make the application of stochastic optimal control both feasible and necessary. A primary production model was used to simulate shrub responses and harvest yields under a variety of climatic regimes and defoliation patterns. The simulation results then were used in an optimization model to determine optimal defoliation strategies. The latter model encodes an algorithm for finite state, finite action, infinite discrete time horizon Markov decision processes. Three questions were addressed: (i) What effect do changes in weather patterns have on optimal management strategies? (ii) What effect does the discounting of future returns have? (iii) How do the optimal strategies perform relative to certain fixed defoliation strategies? An analysis was performed for the three shrub species, winterfat (Ceratoides lanata), shadscale (Atriplex confertifolia) and big sagebrush (Artemisia tridentata). In general, the results indicate substantial differences among species in optimal control strategies, which are associated with differences in physiological and morphological characteristics. Optimal policies for big sagebrush varied less with variation in climate, reserve levels and discount rates than did either shadscale or winterfat. This was attributed primarily to the overwintering of photosynthetically active tissue and to metabolic activity early in the growing season. Optimal defoliation of shadscale and winterfat generally was more responsive to differences in plant vigor and climate, reflecting the sensitivity of these species to utilization and replenishment of carbohydrate reserves. Similarities could be seen in the influence of both the discount rate and the climatic patterns on optimal harvest strategics. In general, decreases in either the discount rate or in the frequency of favorable weather patterns lcd to a more conservative defoliation policy. This did not hold, however, for plants in states of low vigor. Optimal control for shadscale and winterfat tended to stabilize on a policy of heavy defoliation stress, followed by one or more seasons of rest. Big sagebrush required a policy of heavy summer defoliation when sufficient active shoot material is present at the beginning of the growing season. The comparison of fixed and optimal strategies indicated considerable improvement in defoliation yields when optimal strategies are followed. The superior performance was attributable to increased defoliation of plants in states of high vigor. Improvements were found for both discounted and undiscounted yields.

Journal of Environmental Management↗
USGS2016

Cryptic invasion of Northern Leopard Frogs ( Rana pipiens ) across phylogeographic boundaries and a dilemma for conservation of a declining amphibian

Anthropogenic introduction of species is a major contributor to loss of biodiversity. Translocations within the range of a species are less frequently recognized, but have the potential for negative effects as well. Genetic mixing may lead to loss of local adaptations or further decline through outbreeding depression. These cryptic invasions may be quite difficult to recognize, but genetic tools can be used to recognize and monitor such intraspecific introductions. Conversely, translocations within species can be an important conservation tool to reduce inbreeding depression and replace lost genetic diversity. Thus, cryptic invasions can be either an aid or a hindrance to conservation efforts. We tested for the presence of non-native genotypes and assessed the extent and nature of introgression in populations of Northern Leopard Frog ( Rana pipiens ) in the southwestern US, where populations have declined to a few remnant populations. The most abundant and diverse complex of populations in the region contained a mitochondrial haplotype that was not native to the western US, probably resulting from the introduction of released pets, laboratory animals, or release during fish stocking. These non-native haplotypes were well integrated into a large complex of ponds and lakes, contributing to high genetic diversity in this area. Logistically, the geographic extent of non-native genetic influence within this population precludes eliminating or controlling the non-native component of this population. We recommend assessing the progress and fate of the introgression over time—along with population fitness parameters—to determine whether this introduction is beneficial or detrimental to population persistence. Meanwhile, translocations from nearby locations with similar environmental conditions have the best prospects for avoiding problems with outbreeding depression in other declining populations and will also most effectively preserve regional genetic diversity.

Biological Invasions↗
USGS2018

Demographic response of Louisiana Waterthrush, a stream obligate songbird of conservation concern, to shale gas development

Shale gas development continues to outpace the implementation of best management practices for wildlife affected by development. We examined demographic responses of the Louisiana Waterthrush ( Parkesia motacilla ) to shale gas development during 2009–2011 and 2013–2015 in a predominantly forested landscape in West Virginia, USA. Forest cover across the study area decreased from 95% in 2008 to 91% in 2015, while the area affected by shale gas development increased from 0.4% to 3.9%. We quantified nest survival and productivity, a source–sink threshold, riparian habitat quality, territory density, and territory length by monitoring 58.1 km of forested headwater streams ( n = 14 streams). Across years, we saw annual variability in nest survival, with a general declining trend over time. Of 11 a priori models tested to explain nest survival ( n = 280 nests), 4 models that included temporal, habitat, and shale gas covariates were supported, and 2 of these models accounted for most of the variation in daily nest survival rate. After accounting for temporal effects (rainfall, nest age, and time within season), shale gas development had negative effects on nest survival. Population-level nest productivity declined and individual productivity was lower in areas disturbed by shale gas development than in undisturbed areas, and a source–sink threshold suggested that disturbed areas were more at risk of being sink habitat. Riparian habitat quality scores, as measured by a U.S. Environmental Protection Agency index and a waterthrush-specific habitat suitability index, differed by year and were negatively related to the amount of each territory disturbed by shale gas development. Territory density was not related to the amount of shale gas disturbance, but decreased over time as territory lengths increased. Overall, our results suggest a decline in waterthrush site quality as shale gas development increases, despite relatively small site-wide forest loss.

West Virginia↗
USGS2011

Compensatory effects of recruitment and survival when amphibian populations are perturbed by disease

The need to increase our understanding of factors that regulate animal population dynamics has been catalysed by recent, observed declines in wildlife populations worldwide. Reliable estimates of demographic parameters are critical for addressing basic and applied ecological questions and understanding the response of parameters to perturbations (e.g. disease, habitat loss, climate change). However, to fully assess the impact of perturbation on population dynamics, all parameters contributing to the response of the target population must be estimated. We applied the reverse‐time model of Pradel in Program mark to 6 years of capture–recapture data from two populations of Anaxyrus boreas (boreal toad) populations, one with disease and one without. We then assessed a priori hypotheses about differences in survival and recruitment relative to local environmental conditions and the presence of disease. We further explored the relative contribution of survival probability and recruitment rate to population growth and investigated how shifts in these parameters can alter population dynamics when a population is perturbed. High recruitment rates (0·41) are probably compensating for low survival probability (range 0·51–0·54) in the population challenged by an emerging pathogen, resulting in a relatively slow rate of decline. In contrast, the population with no evidence of disease had high survival probability (range 0·75–0·78) but lower recruitment rates (0·25). Synthesis and applications. We suggest that the relationship between survival and recruitment may be compensatory, providing evidence that populations challenged with disease are not necessarily doomed to extinction. A better understanding of these interactions may help to explain, and be used to predict, population regulation and persistence for wildlife threatened with disease. Further, reliable estimates of population parameters such as recruitment and survival can guide the formulation and implementation of conservation actions such as repatriations or habitat management aimed to improve recruitment.

Journal of Applied Ecology↗
USGS1985

Potential impacts of discharging tertiary-treated wastewater into Port Royal Sound, South Carolina

An assessment of physical characteristics of Port Royal Sound was combined with the results of a dye tracer study and with data collected from a previous environmental study to describe the impact on the water quality from discharging tertiary treated wastewater into the sound. Calculated velocities for the time of maximum velocity in the tidal cycle ranged from 2.32 ft/sec near the bottom to 4.65 ft/sec near the surface of the sound in a cross section in the vicinity of a proposed wastewater outfall. Vertical velocity distributions calculated for the time of maximum velocity were similar at all stations at which velocities were measured except the station in shallow water near the shore. A recent bathymetric chart of the vicinity of the proposed outfall indicates that a bar extends farther along the northern shore of Hilton Head Island than indicated on earlier nautical charts of Port Royal Sound. Continued extension of this bar could alter the impact on water quality from discharge of treated wastewater into the sound. Further study may be needed to monitor changes in the bar if the outfall is located between the bar and Hilton Head Island. Conservative calculations based on the results of the dye tracer study indicate that the discharge of 10.9 million gallons/day of wastewater having concentrations of biochemical oxygen demand and suspended solids of 15 mg/L will result in a maximum cumulative increase in concentrations of biochemical oxygen demand of < 0.01 mg/L and no increase in concentrations of suspended solids at high slack tide in the part of Port Royal Sound most affected by the proposed wastewater discharge. (Author 's abstract)

South Carolina↗
USGS2017

Putting flow-ecology relationships into practice: A decision-support system to assess fish community response to water-management scenarios

This paper presents a conceptual framework to operationalize flow–ecology relationships into decision-support systems of practical use to water-resource managers, who are commonly tasked with balancing multiple competing socioeconomic and environmental priorities. We illustrate this framework with a case study, whereby fish community responses to various water-management scenarios were predicted in a partially regulated river system at a local watershed scale. This case study simulates management scenarios based on interactive effects of dam operation protocols, withdrawals for municipal water supply, effluent discharges from wastewater treatment, and inter-basin water transfers. Modeled streamflow was integrated with flow–ecology relationships relating hydrologic departure from reference conditions to fish species richness, stratified by trophic, reproductive, and habitat characteristics. Adding a hypothetical new water-withdrawal site was predicted to increase the frequency of low-flow conditions with adverse effects for several fish groups. Imposition of new reservoir release requirements was predicted to enhance flow and fish species richness immediately downstream of the reservoir, but these effects were dissipated further downstream. The framework presented here can be used to translate flow–ecology relationships into evidence-based management by developing decision-support systems for conservation of riverine biodiversity while optimizing water availability for human use.

Water↗
USGS2019

Monitoring boreal avian populations: How can we estimate trends and trajectories from noisy data?

Substantial effort has been dedicated to developing reliable monitoring schemes for North American bird populations, but our ability to monitor bird populations in the boreal forest remains limited because of the sparsity of long-term data sets, particularly in northerly regions. Given the importance of the boreal forest for many migratory birds, we set out to (1) summarize the main challenges associated with monitoring avian populations, (2) describe the available statistical tools for population monitoring and their applications, and (3) identify future directions to overcome current challenges in monitoring bird populations in the boreal forest. Defining and delineating populations of interest and identifying the drivers that affect those populations present the greatest current challenges. This is because migratory birds may be affected by many population-limiting processes at different stages of their annual life cycles. These factors are often hierarchically structured and can influence populations at the local, regional, or continental scales. Some of the challenges associated with delineating populations and identifying population drivers can be addressed via the plethora of sampling and analytic methods available to examine population change over time. Choosing the proper analytic methods depends on the goals of the study and the nature of the data such as single or multiple populations, repeated occurrence or count-based surveys, or demographic rates. Recent advances in hierarchical and integrated population models make these analytic approaches some of the most promising avenues for the development of future methods. However, these tools require large data sets, and acquiring sufficient data on bird populations and potential explanatory variables is difficult in the boreal forest. If the current challenges to monitoring birds in the boreal forest are to be overcome, serious effort should be dedicated to integrating existing data and making them accessible. Enhancing survey effort through multispecies surveys will also play an important role. Implementing spatially balanced sampling plans with a rotating panel design could balance the trade-offs between spatial versus temporal replication at an affordable cost. Improving the accessibility of environmental covariates that are spatially and temporally explicit would also enable development of mechanistic population models that improve our understanding of migratory bird population dynamics. Finally, given that long-term monitoring programs can take many decades before delivering reliable population trends and that organizational priorities often change over time, we suggest that collaborative efforts will help ensure the long-term survival of new monitoring programs.

Avian Conservation and Ecology↗
USGS2017

Frogs on the beach: Ecology of California Red-legged Frogs ( Rana draytonii ) in coastal dune drainages

California Red-legged Frogs (Rana draytonii) are typically regarded as inhabitants of permanent ponds, marshes, and slow-moving streams, but their ecology in other habitats, such as drainages among coastal dunes, remains obscure. Because coastal dune ecosystems have been degraded by development, off-highway vehicle use, stabilization, and invasive species, these unique ecosystems are the focus of restoration efforts. To better understand the ecology of California Red-legged Frogs in coastal dune ecosystems and to avoid and minimize potential negative effects of dune restoration activities on these rare frogs, we studied their spatial ecology, habitat selection, and survival in coastal dune drainages at Point Reyes National Seashore, California, USA. All 22 radio-marked frogs remained in their home drainages throughout the spring and summer of 2015 and, with some notable exceptions, most remained close to water. Local convex hull home ranges of four out of five California Red-legged Frogs with > 20 observations in dunes were < 1,600 m2 . At the population level, frogs were 1.7 (95% credible interval, 1.2‒4.4) times more likely to select sites 1 m closer to water, and were 83 (2.0‒17,000) times more likely to select sites with 10% greater percentage cover of logs that served as refuges from environmental extremes and predators. On average, California Red-legged Frogs avoided the invasive plants Iceplant (Carpobrotus edulis) and European Beachgrass (Ammophila arenaria). Frogs were 0.68 (0.32‒0.89) and 0.55 (0.24‒0.75) times as likely to select areas that had 10% greater cover of these plants, respectively. Assuming constant risk of mortality, California Redlegged Frogs had an annual survival rate of 0.70 (0.27‒0.96) in coastal dune drainages. Our results indicate that coastal dune drainages provide a locally important habitat for California Red-legged Frogs. Restoration practices that maintain wetted drainages with logjams are likely to benefit California Red-legged Frogs.

Herpetological Conservation and Biology↗
USGS1979

Uptake of methoxychlor from food and water by the American toad (Bufo americanus)

Various studies (Mulla et al. 1963; Ferguson and Gilbert 1967; Cooke 1973) have examined the effects of pesticides on anuran amphibians, but the routes of contaminant uptake by transformed amphibians have not been evaluated. The need of frogs and toads to imbibe water from natural surface water would seem to make them vulnerable to uptake from this source. Fish are known to accumulate pesticides from both food and water (Jarvinen et al. 1977). Toads are more terrestrial and tend to lose water less readily than most other amphibians (Thorson and Svihla 1943); hence they should he a conservative estimator of the potential for uptake of pesticides from water. Methoxychlor is an analogue of DDT and has been widely used to replace it. It is a good model of many pesticides in current use in its low persistence in animal tissues (Gardner and Bailey 1975), and its long half life in water (Wolfe et al. 1977). It is also suitable for study because of its relatively low toxicity to amphibians (Kaplan and Overpeck 1964) and its easily detected residues. In the present study we measured the accumulation of methoxychlor from food and water in a preliminary evaluation of the two routes of exposure.

Bulletin of Environmental Contamination and Toxico↗
USGS1977

Ground-water resources of the North Beach Peninsula, Pacific County, Washington

The anticipated water demand of 425 million gallons per year for the North Beach Peninsula, Pacific County, Wash., can be met by properly developing the ground-water supplies of the area's water-table aquifer. Of the approximately 77 inches of precipitation on the peninsula, an estimated 23 inches is lost to evapotranspiration, and approximately 36 inches is discharged by the water-table aquifer into the ocean and bay. The remaining water either runs off the surface or is leaked to a deeper aquifer that ultimately discharges to the ocean. In some areas of the peninsula, particularly those that are low lying and covered with poorly permeable soils, runoff is promoted by an artificial drainage system developed to alleviate waterlogging. In these areas, it is estimated that natural discharge through the aquifer would be less than that of the artificial drainage system. By a conservative estimate, at least 12 inches of the water that discharges naturally through the aquifer is available for additional development. This quantity of water is approximately equivalent to 860,000 gallons per day or 320 million gallons per year per mile of peninsula length. Under specified idealized conditions wells spaced at least 1,000 feet apart along the major axis of the peninsula and pumped at average rates of no more than 80 gallons per minute would ensure that water-level declines do not exceed 6 feet near the wells and 1 foot at the shoreline, thereby preventing seawater intrusion. Lowering of the water table may be beneficial in reducing waterlogging problems, but care must be taken not to lower the levels near cranberry bogs, which require a shallow water table. Treatment of the otherwise good quality water for iron may be required, as about 75 percent of the well water sampled from the aquifer had iron concentrations in excess of limits recommended by the U.S. Environmental Protection Agency.

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