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At least 829 records · Page 46Linked to original sources
USGS2024

The dynamic feasibility of resisting (R), accepting (A), or directing (D) ecological change

Ecological transformations are occurring as a result of climate change, challenging traditional approaches to land management decision-making. The resist–accept–direct (RAD) framework helps managers consider how to respond to this challenge. We examined how the feasibility of the choices to resist, accept, and direct shifts in complex and dynamic ways through time. We considered 4 distinct types of social feasibility: regulatory, financial, public, and organizational. Our commentary is grounded in literature review and the examples that exist but necessarily has speculative elements because empirical evidence on this newly emerging management strategy is scarce. We expect that resist strategies will become less feasible over time as managers encounter situations where resisting is ecologically, by regulation, financially, or publicly not feasible. Similarly, we expect that as regulatory frameworks increasingly permit their use, if costs decrease, and if the public accepts them, managers will increasingly view accept and direct strategies as more viable options than they do at present. Exploring multiple types of feasibility over time allows consideration of both social and ecological trajectories of change in tandem. Our theorizing suggested that deepening the time horizon of decision-making allows one to think carefully about when one should adopt different approaches and how to combine them over time.

Conservation Biology↗
USGS2017

Decision support frameworks and tools for conservation

The practice of conservation occurs within complex socioecological systems fraught with challenges that require transparent, defensible, and often socially engaged project planning and management. Planning and decision support frameworks are designed to help conservation practitioners increase planning rigor, project accountability, stakeholder participation, transparency in decisions, and learning. We describe and contrast five common frameworks within the context of six fundamental questions (why, who, what, where, when, how) at each of three planning stages of adaptive management (project scoping, operational planning, learning). We demonstrate that decision support frameworks provide varied and extensive tools for conservation planning and management. However, using any framework in isolation risks diminishing potential benefits since no one framework covers the full spectrum of potential conservation planning and decision challenges. We describe two case studies that have effectively deployed tools from across conservation frameworks to improve conservation actions and outcomes. Attention to the critical questions for conservation project planning should allow practitioners to operate within any framework and adapt tools to suit their specific management context. We call on conservation researchers and practitioners to regularly use decision support tools as standard practice for framing both practice and research.

Conservation Letters↗
USGS2019

Different management strategies are optimal for combating disease in East Texas cave versus culvert hibernating bat populations

Management decisions for species impacted by emerging infectious diseases are challenging when there are uncertainties in the effectiveness of management actions. Wildlife managers must balance trade‐offs between mitigating the effects of the disease and the associated consequences on other aspects of the managed system. An example of this challenge is exemplified in the response to white‐nose syndrome (WNS), a disease of hibernating bats. The fungal pathogen that causes WNS, Pseudogymnoascus destructans , continues to spread throughout North America. Texas, recently confirmed positive for the fungus, has documented 33 bat species in the state, with nearly half of those species naïve to the pathogen. We explicitly incorporated multiple management objectives, uncertainty, and risk in the Texas Parks and Wildlife Department decision to manage East Texas populations of the tri‐colored bat ( Perimyotis subflavus ), a species highly susceptible to WNS. Alternatives included individual actions that act against P . destructans or benefit bats, a no active management option, and combinations of actions. Although our main objective was to identify WNS mitigation measures for tri‐colored bats in culverts, we also considered the transferability of the decision for natural caves. In this scenario, the optimal decision differed for culverts and caves, with a “portfolio” combination of actions ranking as the best alternative for culverts and a single vaccine alternative for caves. Because the top management alternatives differed markedly between these two systems, finding treatments that have broad application is likely infeasible, given that each management decision is characterized by different mixtures of competing objectives.

Texas↗
USGS2021

Mechanistic invasive species management models and their application in conservation

Management strategies to address the challenges associated with invasive species are critical for effective conservation. An increasing variety of mathematical models offer insight into invasive populations, and can help managers identify cost effective prevention, control, and eradication actions. Despite this, as model complexity grows, so does the inaccessibility of these tools to conservation practitioners making decisions about management. Here, we seek to narrow the science-practice gap by reviewing invasive species management models (ISMMs). We define ISMMs as mechanistic models used to explore invasive species management strategies, and include reaction-advection–diffusion models, integrodifference equations, gravity models, particle transport models, nonspatial and spatial discrete-time population growth models, cellular automata, and individual-based models. For each approach, we describe the model framework and its implementation, discuss strengths and weaknesses, and give examples of conservation applications. We conclude by discussing how ISMMs can be used in concert with adaptive management to address scientific uncertainties impeding action and with multiple objective decision processes to evaluate tradeoffs among management objectives. We undertook this review to support more effective decision-making involving invasive species by providing conservation practitioners with the information they need to identify tools most useful for their applications.

Conservation Science and Practice↗
USGS2026

Management strategy evaluation for salmon habitat restoration and hatchery supplementation

A primary challenge in conservation is the evaluation of management actions. For species with complex life histories, this evaluation is particularly challenging, and quantitative models are needed to understand how effects on particular life stages translate to objectives such as an acceptably low extinction risk or large abundance. We modeled the effects of increasing juvenile survival (as would result from habitat restoration) and hatchery supplementation on the achievement of recovery objectives for endangered Chinook salmon ( Oncorhynchus tshawytscha ) in the Wenatchee River Basin of Washington State. We evaluated these actions using simulations with a model that accounted for density-dependence operating in juvenile rearing habitat. Simulations indicated that there were compounding benefits of increasing survival in both natal streams, where juveniles are born, and in downstream areas where a portion of juveniles rear. We also found that the marginal benefit of producing more hatchery fish declined as juvenile survival improved. Simulations suggested that achieving recovery targets for abundance of spring-run Chinook salmon in the Wenatchee River would require more than a 150% increase in juvenile survival, barring increases in survival in other portions of the life cycle. Therefore, comprehensive management focusing on multiple factors affecting survival may be required to meet recovery criteria.

Washington↗
USGS2023

Dispersive currents explain patterns of population connectivity in an ecologically and economically important fish

How to identify the drivers of population connectivity remains a fundamental question in ecology and evolution. Answering this question can be challenging in aquatic environments where dynamic lake and ocean currents coupled with high levels of dispersal and gene flow can decrease the utility of modern population genetic tools. To address this challenge, we used RAD-Seq to genotype 959 yellow perch ( Perca flavescens ), a species with an ~40-day pelagic larval duration (PLD), collected from 20 sites circumscribing Lake Michigan. We also developed a novel, integrative approach that couples detailed biophysical models with eco-genetic agent-based models to generate “predictive” values of genetic differentiation. By comparing predictive and empirical values of genetic differentiation, we estimated the relative contributions for known drivers of population connectivity (e.g., currents, behavior, PLD). For the main basin populations (i.e., the largest contiguous portion of the lake), we found that high gene flow led to low overall levels of genetic differentiation among populations ( F ST = 0.003). By far the best predictors of genetic differentiation were connectivity matrices that were derived from periods of time when there were strong and highly dispersive currents. Thus, these highly dispersive currents are driving the patterns of population connectivity in the main basin. We also found that populations from the northern and southern main basin are slightly divergent from one another, while those from Green Bay and the main basin are highly divergent ( F ST = 0.11). By integrating biophysical and eco-genetic models with genome-wide data, we illustrate that the drivers of population connectivity can be identified in high gene flow systems.

Lake Michigan↗
USGS2015

Trade-offs in osmoregulation and parallel shifts in molecular function follow ecological transitions to freshwater in the Alewife

Adaptation to freshwater may be expected to reduce performance in seawater because these environments represent opposing selective regimes. We tested for such a trade-off in populations of the Alewife ( Alosa pseudoharengus ). Alewives are ancestrally anadromous, and multiple populations have been independently restricted to freshwater (landlocked). We conducted salinity challenge experiments, whereby juvenile Alewives from one anadromous and multiple landlocked populations were exposed to freshwater and seawater on acute and acclimation timescales. In response to acute salinity challenge trials, independently derived landlocked populations varied in the degree to which seawater tolerance has been lost. In laboratory-acclimation experiments, landlocked Alewives exhibited improved freshwater tolerance, which was correlated with reductions in seawater tolerance and hypo-osmotic balance, suggesting that trade-offs in osmoregulation may be associated with local adaptation to freshwater. We detected differentiation between life-history forms in the expression of an ion-uptake gene ( NHE3 ), and in gill Na + /K + -ATPase activity. Trade-offs in osmoregulation, therefore, may be mediated by differentiation in ion-uptake and salt-secreting pathways.

Evolution↗
USGS2022

Thirteen novel ideas and underutilized resources to support progress towards a range-wide American eel stock assessment

A robust assessment of the American eel ( Anguilla rostrata ) stock, required to guide conservation efforts, is challenged by the species’ vast range, high variability in demographic parameters and data inadequacies. Novel ideas and underutilised resources that may assist both analytic assessments and spatially oriented modelling include (1) species and environmental databases; (2) mining of data from scattered sources; (3) infilling of data gaps by spatial analysis; (4) age estimation from measurements of DNA methylation; evaluation of eel abundance by (5) larval, (6) glass-bottom boat, (7) net enclosure and (8) eDNA surveys; (9) accounting for dam-induced habitat increases in eel watercourse modelling; (10) spatially oriented modelling with and without temporal components; (11) geographically nested modelling of glass eel recruitment; (12) spawner per recruit modelling and (13) life cycle modelling to examine larval allocation effects. Eel biologists are too few to gather the required assessment data across all of the species’ range. Public posting of electrofishing and eDNA metabarcoding data sets and the use of machine learning techniques to comprehensively inventory small dams will help meet some data needs. These approaches address only a small proportion of the assessment challenges that face American eels. Worldwide collaboration amongst Anguilla scientists is a key enabler of progress towards stock assessment goals.

North America, South America↗
USGS2025

Three decades of World Recreational Fishing Conferences: What have we learned about the dynamics of recreational fisheries?

Recreational fishing extends beyond catching fish, connecting individuals with nature, generating environmental stewards and contributing significantly to both local, regional and national economies. Assessing potential impacts on ecosystems and social-ecological systems requires dedicated multi- and interdisciplinary research and integrative management and policy approaches. Managing recreational fisheries effectively also necessitates transdisciplinary thinking, yet this poses continued challenges, as researchers and managers balance specialized expertise with innovative, boundary-crossing perspectives in light of limited funding in a rapidly changing social-ecological environment. The World Recreational Fishing Conference (WRFC) serves as the leading global scientific forum for addressing these challenges, fostering interdisciplinary exchange among scientists, managers, policy makers and stakeholders. The papers in this special issue represent the output of the last WRFC in Melbourne, Australia in 2023. By reviewing the content of the papers published in the present special issue, we illustrate the critical role of collaborative spaces, such as the WRFC, in bridging different expertise and approaches and fostering innovation, thereby securing adaptive management and conservation of recreational fisheries in response to global changes. Evaluating the development of the WRFC over three decades highlights how this conference series represents a leading think tank serving the entire network of recreational fisheries professionals globally.

Fisheries Management and Ecology↗
USGS2015

Human activities and climate variability drive fast-paced change across the world's estuarine-coastal ecosystems

Time series of environmental measurements are essential for detecting, measuring and understanding changes in the Earth system and its biological communities. Observational series have accumulated over the past 2–5 decades from measurements across the world's estuaries, bays, lagoons, inland seas and shelf waters influenced by runoff. We synthesize information contained in these time series to develop a global view of changes occurring in marine systems influenced by connectivity to land. Our review is organized around four themes: (i) human activities as drivers of change; (ii) variability of the climate system as a driver of change; (iii) successes, disappointments and challenges of managing change at the sea-land interface; and (iv) discoveries made from observations over time. Multidecadal time series reveal that many of the world's estuarine–coastal ecosystems are in a continuing state of change, and the pace of change is faster than we could have imagined a decade ago. Some have been transformed into novel ecosystems with habitats, biogeochemistry and biological communities outside the natural range of variability. Change takes many forms including linear and nonlinear trends, abrupt state changes and oscillations. The challenge of managing change is daunting in the coastal zone where diverse human pressures are concentrated and intersect with different responses to climate variability over land and over ocean basins. The pace of change in estuarine–coastal ecosystems will likely accelerate as the human population and economies continue to grow and as global climate change accelerates. Wise stewardship of the resources upon which we depend is critically dependent upon a continuing flow of information from observations to measure, understand and anticipate future changes along the world's coastlines.

Global Change Biology↗
USGS2018

Adapting management to a changing world: Warm temperatures, dry soil, and interannual variability limit restoration success of a dominant woody shrub in temperate drylands

Restoration and rehabilitation of native vegetation in dryland ecosystems, which encompass over 40% of terrestrial ecosystems, is a common challenge that continues to grow as wildfire and biological invasions transform dryland plant communities. The difficulty in part stems from low and variable precipitation, combined with limited understanding about how weather conditions influence restoration outcomes, and increasing recognition that one‐time seeding approaches can fail if they do not occur during appropriate plant establishment conditions. The sagebrush biome, which once covered over 620,000 km 2 of western North America, is a prime example of a pressing dryland restoration challenge for which restoration success has been variable. We analyzed field data on Artemisia tridentata (big sagebrush) restoration collected at 771 plots in 177 wildfire sites across its western range, and used process‐based ecohydrological modeling to identify factors leading to its establishment. Our results indicate big sagebrush occurrence is most strongly associated with relatively cool temperatures and wet soils in the first spring after seeding. In particular, the amount of winter snowpack, but not total precipitation, helped explain the availability of spring soil moisture and restoration success. We also find considerable interannual variability in the probability of sagebrush establishment. Adaptive management strategies that target seeding during cool, wet years or mitigate effects of variability through repeated seeding may improve the likelihood of successful restoration in dryland ecosystems. Given consistent projections of increasing temperatures, declining snowpack, and increasing weather variability throughout midlatitude drylands, weather‐centric adaptive management approaches to restoration will be increasingly important for dryland restoration success.

Great Basin↗
USGS2014

DigitalCrust – a 4D data system of material properties for transforming research on crustal fluid flow

Fluid circulation in the Earth's crust plays an essential role in surface, near surface, and deep crustal processes. Flow pathways are driven by hydraulic gradients but controlled by material permeability, which varies over many orders of magnitude and changes over time. Although millions of measurements of crustal properties have been made, including geophysical imaging and borehole tests, this vast amount of data and information has not been integrated into a comprehensive knowledge system. A community data infrastructure is needed to improve data access, enable large-scale synthetic analyses, and support representations of the subsurface in Earth system models. Here, we describe the motivation, vision, challenges, and an action plan for a community-governed, four-dimensional data system of the Earth's crustal structure, composition, and material properties from the surface down to the brittle–ductile transition. Such a system must not only be sufficiently flexible to support inquiries in many different domains of Earth science, but it must also be focused on characterizing the physical crustal properties of permeability and porosity, which have not yet been synthesized at a large scale. The DigitalCrust is envisioned as an interactive virtual exploration laboratory where models can be calibrated with empirical data and alternative hypotheses can be tested at a range of spatial scales. It must also support a community process for compiling and harmonizing models into regional syntheses of crustal properties. Sustained peer review from multiple disciplines will allow constant refinement in the ability of the system to inform science questions and societal challenges and to function as a dynamic library of our knowledge of Earth's crust.

Geofluids↗
USGS2017

Instrumentation development for In Situ 40Ar/39Ar planetary geochronology

The chronology of the Solar System, particularly the timing of formation of extra-terrestrial bodies and their features, is an outstanding problem in planetary science. Although various chronological methods for in situ geochronology have been proposed (e.g., Rb-Sr, K-Ar), and even applied (K-Ar), the reliability, accuracy, and applicability of the 40 Ar/ 39 Ar method makes it by far the most desirable chronometer for dating extra-terrestrial bodies. The method however relies on the neutron irradiation of samples, and thus a neutron source. Herein, we discuss the challenges and feasibility of deploying a passive neutron source to planetary surfaces for the in situ application of the 40 Ar/ 39 Ar chronometer. Requirements in generating and shielding neutrons, as well as analysing samples are described, along with an exploration of limitations such as mass, power and cost. Two potential solutions for the in situ extra-terrestrial deployment of the 40 Ar/ 39 Ar method are presented. Although this represents a challenging task, developing the technology to apply the 40 Ar/ 39 Ar method on planetary surfaces would represent a major advance towards constraining the timescale of solar system formation and evolution.

Geostandards and Geoanalytical Research↗
USGS2009

Disease, predation and demography: Assessing the impacts of bovine tuberculosis on African buffalo by monitoring at individual and population levels

Summary Understanding the effects of disease is critical to determining appropriate management responses, but estimating those effects in wildlife species is challenging. We used bovine tuberculosis (BTB) in the African buffalo Syncerus caffer population of Kruger National Park, South Africa, as a case study to highlight the issues associated with estimating chronic disease effects in a long‐lived host. We used known and radiocollared buffalo, aerial census data, and a natural gradient in pathogen prevalence to investigate if: (i) at the individual level, BTB infection reduces reproduction; (ii) BTB infection increases vulnerability to predation; and (iii) at the population level, increased BTB prevalence causes reduced population growth. There was only a marginal reduction in calving success associated with BTB infection, as indexed by the probability of sighting a known adult female with or without a calf ( P = 0·065). Since 1991, BTB prevalence increased from 27 to 45% in the southern region and from 4 to 28% in the central region of Kruger National Park. The prevalence in the northern regions was only 1·5% in 1998. Buffalo population growth rates, however, were neither statistically different among regions nor declining over time. Lions Panthera leo did not appear to preferentially kill test‐positive buffalo. The best (Akaike's Information Criterion corrected for small sample size) AIC c model with BTB as a covariate [exp(β) = 0·49; 95% CI = (0·24–1·02)] suggested that the mortality hazard for positive individuals was no greater than for test‐negative individuals. Synthesis and applications . Test accuracy, time‐varying disease status, and movement among populations are some of the issues that make the detection of chronic disease impacts challenging. For these reasons, the demographic impacts of bovine tuberculosis in the Kruger National Park remain undetectable despite 6 years of study on known individuals and 40 years of population counts. However, the rainfall and forage conditions during this study were relatively good and the impacts of many chronic diseases may be a non‐linear function of environmental conditions such that they are only detectable in stressful periods.

Kruger National Park↗
USGS2010

Quantifying restoration success and recovery in a metal-polluted stream: A 17-year assessment of physicochemical and biological responses

Evaluating the effectiveness of stream restoration is often challenging because of the lack of pre-treatment data, narrow focus on physicochemical measures and insufficient post-restoration monitoring. Even when these fundamental elements are present, quantifying restoration success is difficult because of the challenges associated with distinguishing treatment effects from seasonal variation, episodic events and long-term climatic changes.2. We report results of one of the most comprehensive and continuous records of physical, chemical and biological data available to assess restoration success for a stream ecosystem in North America. Over a 17 year period we measured seasonal and annual changes in metal concentrations, physicochemical characteristics, macroinvertebrate communities, and brown trout Salmo trutta populations in the Arkansas River, a metal-contaminated stream in Colorado, USA.3. Although we observed significant improvements in water quality after treatment, the effectiveness of restoration varied temporally, spatially and among biological response variables. The fastest recovery was observed at stations where restoration eliminated point sources of metal contamination. Recovery of macroinvertebrates was significantly delayed at some stations because of residual sediment contamination and because extreme seasonal and episodic variation in metal concentrations prevented recolonization by sensitive species. Synthesis and applications. Because recovery trajectories after the removal of a stressor are often complex or nonlinear, long-term studies are necessary to assess restoration success within the context of episodic events and changes in regional climate. The observed variation in recovery among chemical and biological endpoints highlights the importance of developing objective criteria to assess restoration success. Although the rapid response of macroinvertebrates to reduced metal concentrations is encouraging, we have previously demonstrated that benthic communities from the Arkansas River remained susceptible to other novel anthropogenic stressors. We suggest that the resistance or resilience of benthic macroinvertebrate communities to novel stressors may be effective indicators of restoration success that can account for the non-additive (e.g. synergistic) nature of compound perturbations. ?? 2010 The Authors. Journal compilation ?? 2010 British Ecological Society.

Journal of Applied Ecology↗
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↗
USGS2008

Elevated CO 2 enhances biological contributions to elevation change in coastal wetlands by offsetting stressors associated with sea-level rise

1. Sea-level rise, one indirect consequence of increasing atmospheric CO 2 , poses a major challenge to long-term stability of coastal wetlands. An important question is whether direct effects of elevated CO 2 on the capacity of marsh plants to accrete organic material and to maintain surface elevations outweigh indirect negative effects of stressors associated with sea-level rise (salinity and flooding). 2. In this study, we used a mesocosm approach to examine potential direct and indirect effects of atmospheric CO 2 concentration, salinity and flooding on elevation change in a brackish marsh community dominated by a C 3 species, Schoenoplectus americanus, and a C 4 grass, Spartina patens. This experimental design permitted identification of mechanisms and their role in controlling elevation change, and the development of models that can be tested in the field. 3. To test hypotheses related to CO 2 and sea-level rise, we used conventional anova procedures in conjunction with structural equation modelling (SEM). SEM explained 78% of the variability in elevation change and showed the direct, positive effect of S. americanus production on elevation. The SEM indicated that C 3 plant response was influenced by interactive effects between CO 2 and salinity on plant growth, not a direct CO 2 fertilization effect. Elevated CO 2 ameliorated negative effects of salinity on S. americanus and enhanced biomass contribution to elevation. 4. The positive relationship between S. americanus production and elevation change can be explained by shoot-base expansion under elevated CO 2 conditions, which led to vertical soil displacement. While the response of this species may differ under other environmental conditions, shoot-base expansion and the general contribution of C 3 plant production to elevation change may be an important mechanism contributing to soil expansion and elevation gain in other coastal wetlands. 5. Synthesis. Our results revealed previously unrecognized interactions and mechanisms contributing to marsh elevation change, including amelioration of salt stress by elevated CO 2 and the importance of plant production and shoot-base expansion for elevation gain. Identification of biological processes contributing to elevation change is an important first step in developing comprehensive models that permit more accurate predictions of whether coastal marshes will persist with continued sea-level rise or become submerged. ?? 2008 The Authors.

Journal of Ecology↗
USGS2007

Larval Pacific herring, Clupea pallasii (Valenciennes), are highly susceptible to viral haemorrhagic septicaemia and survivors are partially protected after their metamorphosis to juveniles

Pacific herring were susceptible to waterborne challenge with viral haemorrhagic septicaemia virus (VHSV) throughout their early life history stages, with significantly greater cumulative mortalities occurring among VHSV-exposed groups of 9-, 44-, 54- and 76-day-old larvae than among respective control groups. Similarly, among 89-day-1-year-old and 1+year old post-metamorphosed juveniles, cumulative mortality was significantly greater in VHSV-challenged groups than in respective control groups. Larval exposure to VHSV conferred partial protection to the survivors after their metamorphosis to juveniles as shown by significantly less cumulative mortalities among juvenile groups that survived a VHS epidemic as larvae than among groups that were previously nai??ve to VHSV. Magnitude of the protection, measured as relative per cent survival, was a direct function of larval age at first exposure and was probably a reflection of gradual developmental onset of immunocompetence. These results indicate the potential for easily overlooked VHS epizootics among wild larvae in regions where the virus is endemic and emphasize the importance of early life history stages of marine fish in influencing the ecological disease processes. ?? 2007 The Authors.

Journal of Fish Diseases↗