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At least 91 records · Page 5Linked to original sources
USGS2023

Enhancing the predictability of ecology in a changing world: A call for an organism-based approach

Ecology is usually very good in making descriptive explanations of what is observed, but is often unable to make predictions of the response of ecosystems to change. This has implications in a human-dominated world where a suite of anthropogenic stresses are threatening the resilience and functioning of ecosystems that sustain mankind through a range of critical regulating and supporting services. In ecosystems, cause-and-effect relationships are difficult to elucidate because of complex networks of negative and positive feedbacks. Therefore, being able to effectively predict when and where ecosystems could pass into different (and potentially unstable) new states is vitally important under rapid global change. Here, we argue that such better predictions may be reached if we focus on organisms instead of species, because organisms are the principal biotic agents in ecosystems that react directly on changes in their environment. Several studies show that changes in ecosystems may be accurately described as the result of changes in organisms and their interactions. Organism-based theories are available that are simple and derived from first principles, but allow many predictions. Of these we discuss Trait-based Ecology, Agent Based Models, and Maximum Entropy Theory of Ecology and show that together they form a logical sequence of approaches that allow organism-based studies of ecological communities. Combining and extending them makes it possible to predict the spatiotemporal distribution of groups of organisms in terms of how metabolic energy is distributed over areas, time, and resources. We expect that this “Organism-based Ecology” (OE) ultimately will improve our ability to predict ecosystem dynamics.

Frontiers in Applied Mathematics and Statistics↗
USGS2016

Mercury in western North America: A synthesis of environmental contamination, fluxes, bioaccumulation, and risk to fish and wildlife

Western North America is a region defined by extreme gradients in geomorphology and climate, which support a diverse array of ecological communities and natural resources. The region also has extreme gradients in mercury (Hg) contamination due to a broad distribution of inorganic Hg sources. These diverse Hg sources and a varied landscape create a unique and complex mosaic of ecological risk from Hg impairment associated with differential methylmercury (MeHg) production and bioaccumulation. Understanding the landscape-scale variation in the magnitude and relative importance of processes associated with Hg transport, methylation, and MeHg bioaccumulation requires a multidisciplinary synthesis that transcends small-scale variability. The Western North America Mercury Synthesis compiled, analyzed, and interpreted spatial and temporal patterns and drivers of Hg and MeHg in air, soil, vegetation, sediments, fish, and wildlife across western North America. This collaboration evaluated the potential risk from Hg to fish, and wildlife health, human exposure, and examined resource management activities that influenced the risk of Hg contamination. This paper integrates the key information presented across the individual papers that comprise the synthesis. The compiled information indicates that Hg contamination is widespread, but heterogeneous, across western North America. The storage and transport of inorganic Hg across landscape gradients are largely regulated by climate and land-cover factors such as plant productivity and precipitation. Importantly, there was a striking lack of concordance between pools and sources of inorganic Hg, and MeHg in aquatic food webs. Additionally, water management had a widespread influence on MeHg bioaccumulation in aquatic ecosystems, whereas mining impacts where relatively localized. These results highlight the decoupling of inorganic Hg sources with MeHg production and bioaccumulation. Together the findings indicate that developing efforts to control MeHg production in the West may be particularly beneficial for reducing food web exposure instead of efforts to simply control inorganic Hg sources.

Science of the Total Environment↗
USGS2019

Where has turtle ecology been, and where is it going?

Over 9000 articles have been published on turtles and tortoises (excluding sea turtles) since 1950 according to the Web of Science, including over 8000 contained in a personal bibliography that we analyze in this paper. Research had a slow start from 1900 to 1950, with mostly anecdotal additions to our knowledge until the contributions of F. Cagle and A. Carr took turtle research to new levels as the cofathers of turtle ecology in the middle of the last century. Books written in 1939, 1952, and 1972 that compiled existing literature on turtles in the United States and Canada set the stage for growing interest in turtles. The first global compilation of turtle species did not become available until 1961. Publication frequency increased in the 1960s and especially the 1970s as interest in turtles grew, and a wave of turtle biologists emerged from doctoral degree programs. We briefly review the contributions of scientists who published extensively on turtle ecology in those and later decades up to the present. We also review advances in our knowledge of various topics, including the global distribution of turtle research efforts; changes in our perceptions of turtle species diversity over time; turtle community ecology; sex ratios, sex-determination, and climate change; overwintering behavior; sexual size dimorphism and sexual dichromatism; analyses of population genetics; turtles and vocalization; and the emergence of turtle conservation biology efforts. We conclude with a discussion of future opportunities and challenges for working with turtles.

Herpetologica↗
USGS2018

Host feeding ecology and trophic position significantly influence isotopic discrimination between a generalist ectoparasite and its hosts: Implications for parasite-host trophic studies

Despite being one of the most prevalent forms of consumerism in ecological communities, parasitism has largely been excluded from food-web models. Stable isotope analysis of consumers and their diets has been widely used in the study of food webs for decades. However, the amount of information regarding parasite stable isotope ecology is limited, restricting the ability of ecologists to use stable isotope analysis to study parasites in food webs. This study took advantage of distinct differences in the feeding ecology and trophic position of different species of fish known to host the same common micropredatory gnathiid isopod to study the effects of host stable isotope ecology on that of the associated micropredator. Blood engorged juvenile gnathiids were in most cases indistinguishable from their hosts' blood, but significant isotope discrimination was observed for adults. Males were generally lower in δ 13 C and δ 15 N than host blood whereas host-specific isotopic discrimination for females varied among the different host species. Model predictions indicated that there is a significant effect of host blood isotope ratios on the rate of carbon and nitrogen isotopic discrimination between gnathiids and their host’s blood. As such, general differences in the feeding ecology and trophic positions of the different host species were reflected in their associated gnathiids, indicating that stable isotope analysis of gnathiids can provide significant details concerning previous hosts. The results presented herein have significant implications for how stable isotopes may be used as a tool to study the trophic dynamics and feeding ecology of gnathiids.

Food Webs↗
USGS2020

Multi‐species occupancy models: Review, roadmap, and recommendations

Recent technological and methodological advances have revolutionized wildlife monitoring. Although most biodiversity monitoring initiatives are geared towards focal species of conservation concern, researchers are increasingly studying entire communities, specifically the spatiotemporal drivers of community size and structure and interactions among species. This has resulted in the emergence of multi‐species occupancy models (MSOMs) as a promising and efficient approach for the study of community ecology. Given the potential of MSOMs for conservation and management action, it is critical to know whether study design and model assumptions are consistent with inference objectives. This is especially true for studies that are designed for a focal species but can give insights about a community. Here, we review the recent literature on MSOMs, identify areas of improvement in the multi‐species study workflow, and provide a reference model for best practices for focal species and community monitoring study design. We reviewed 92 studies published between 2009 and early 2018, spanning 27 countries and a variety of taxa. There is a consistent under‐reporting of details that are central to determining the adequacy of designs for generating data that can be used to make inferences about community‐level patterns of occupancy, including the spatial and temporal extent, types of detectors used, covariates considered, and choice of field methods and statistical tools. This reporting bias could consequently result in skewed estimates, affecting conservation actions and management plans. On the other hand, comprehensive reporting is likely to help researchers working on MSOMs assess the robustness of inferences, in addition to making strides in terms of reproducibility and reusability of data. We use our literature review to inform a roadmap with best practices for MSOM studies, from simulations to design considerations and reporting, for the collection of new data as well as those involving existing datasets.

Ecography↗
USGS2014

SAFRR tsunami scenario: Impacts on California ecosystems, species, marine natural resources, and fisheries

We evaluate the effects of the SAFRR Tsunami Scenario on California’s ecosystems, species, natural resources, and fisheries. We discuss mitigation and preparedness approaches that can be useful in Tsunami planning. The chapter provides an introduction to the role of ecosystems and natural resources in tsunami events (Section 1). A separate section focuses on specific impacts of the SAFRR Tsunami Scenario on California’s ecosystems and endangered species (Section 2). A section on commercial fisheries and the fishing fleet (Section 3) documents the plausible effects on California’s commercial fishery resources, fishing fleets, and communities. Sections 2 and 3 each include practical preparedness options for communities and suggestions on information needs or research. Our evaluation indicates that many low-lying coastal habitats, including beaches, marshes and sloughs, rivers and waterways connected to the sea, as well as nearshore submarine habitats will be damaged by the SAFRR Tsunami Scenario. Beach erosion and complex or high volumes of tsunami-generated debris would pose major challenges for ecological communities. Several endangered species and protected areas are at risk. Commercial fisheries and fishing fleets will be affected directly by the tsunami and indirectly by dependencies on infrastructure that is damaged. There is evidence that in some areas intact ecosystems, notably sand dunes, will act as natural defenses against the tsunami waves. However, ecosystems do not provide blanket protection against tsunami surge. The consequences of ecological and natural resource damage are estimated in the millions of dollars. These costs are driven partly by the loss of ecosystem services, as well as cumulative and follow-on impacts where, for example, increased erosion during the tsunami can in turn lead to subsequent damage and loss to coastal properties. Recovery of ecosystems, natural resources and fisheries is likely to be lengthy and expensive. Preparedness is key to enhancing resilience to ecological impacts.

California↗
USGS2022

Fuel reduction treatments reduce modeled fire intensity in the sagebrush steppe

Increased fire size and frequency coupled with annual grass invasion pose major challenges to sagebrush ( Artemisia spp.) ecosystem conservation, which is currently focused on protecting sagebrush community composition and structure. A common strategy for mitigating potential fire is to use fuel treatments that alter the structure and amount of burnable material, thus reducing fire behavior and creating access points for fire suppression resources. While there is some recent information on the impacts of fuel treatments on ecological communities, we have little information on fuel treatment effectiveness at modifying fire behavior in sagebrush ecosystems. We present 10 years of data on fuel accumulation and the resultant modeled fire behavior in prescribed fire, mowed, herbicide (tebuthiuron or imazapic), and untreated control plots in the Sagebrush Treatment Evaluation Project (SageSTEP) network in the Great Basin, USA. Fuel data (i.e., aboveground burnable live and dead biomass) were collected in each treatment plot at Years 0 (pretreatment), 1, 2, 3, 6, and 10 posttreatment. We used the Fuel and Fire Tool fire behavior modeling program to test whether treatments impacted potential fire behavior. Prescribed fire initially removed 49% of the total fuel load and 75% of shrubs, and fuel loads remained reduced through Year 10. Mowing shifted fuels from the shrub canopy to the ground surface but did not change the total fuel amount. Prescribed fire and mowing increased herbaceous fuel by the second posttreatment year and that trend persisted through Year 10. Tebuthiuron treatments were ineffective at altering fuel loads. Imazapic suppressed herbaceous vegetation by 30% in Years 2 and 3 following treatment. The modified fuel beds in fire and mow treatments resulted in modeled flame lengths that were significantly lower than untreated control plots for the duration of the study, with shorter term reductions in reaction intensity and rate of spread. Understanding fuel treatment effectiveness will allow natural resource managers to evaluate trade-offs between protecting wildlife habitat and reducing the potential for high-intensity wildfire.

Ecosphere↗
USGS2019

Negative frequency-dependent foraging behaviour in a generalist herbivore (Alces alces) and its stabilizing influence on food-web dynamics

1. Resource selection is widely appreciated to be context‐dependent and shaped by both biological and abiotic factors. However, few studies have empirically assessed the extent to which selective foraging behaviour is dynamic and varies in response to environmental conditions for free‐ranging animal populations. 2. Here, we assessed the extent that forage selection fluctuated in response to different environmental conditions for a free‐ranging herbivore, moose (Alces alces), in Isle Royale National Park, over a 10‐year period. More precisely, we assessed how moose selection for coniferous versus deciduous forage in winter varied between geographic regions and in relation to (a) the relative frequency of forage types in the environment (e.g. frequency‐dependent foraging behaviour), (b) moose abundance, (c) predation rate (by grey wolves) and (d) snow depth. These factors are potentially important for their influence on the energetics of foraging. We also built a series of food‐chain models to assess the influence of dynamic foraging strategies on the stability of food webs. 3. Our analysis indicates that moose exhibited negative frequency dependence, by selectively exploiting rare resources. Frequency‐dependent foraging was further mediated by density‐dependent processes, which are likely to be predation, moose abundance or some combination of both. In particular, frequency dependence was weaker in years when predation risk was high (i.e. when the ratio of moose to wolves was relatively low). Selection for conifers was also slightly weaker during deep snow years. 4. The food‐chain analysis indicates that the type of frequency‐dependent foraging strategy exhibited by herbivores had important consequences for the stability of ecological communities. In particular, the dynamic foraging strategy that we observed in the empirical analysis (i.e. negative frequency dependence being mediated by density‐dependent processes) was associated with more stable food web dynamics compared to fixed foraging strategies. 5. The results of this study indicated that forage selection is a complex ecological process, varying in response to both biological (predation and moose density) and abiotic factors (snow depth) and over relatively small spatial scales (between regions). This study also provides a useful framework for assessing the influence of other aspects of foraging behaviour on the stability of food web dynamics.

Michigan↗
USGS2014

Maintaining resilience in the face of climate change

Climate change, when combined with more conventional stress from human exploitation, calls into question the capacity of both existing ecological communities and resource management institutions to experience disturbances while substantially retaining their same functions and identities (Zellmer and Gunderson 2009; Ruhl 2011). In other words, the physical and biological effects of climate change raise fundamental challenges to the resilience of natural ecosystems (Gunderson and Holling 2002). Perhaps more importantly, the projected scope of ecological shifts from global climate change-and uncertainty about such changes-significantly stresses the capacity of legal institutions to manage ecosystem change (Camacho 2009). Existing governmental institutions lack the adaptive capacity to manage such substantial changes to ecological and legal systems. In particular, regulators and managers lack information about ecological effects and alternative management strategies for managing the effects of climate change (Karkkainen 2008; Camacho 2009), as well as the institutional infrastructure for obtaining such information (Peters 2008). A number of recent initiatives have been proposed to address the effects of climate change on ecological systems. However, these nascent programs do not fully meet the needs for developing adaptive capacity. A federal, publicly accessible, and system-wide portal and clearinghouse will help regulators at all levels of government manage the effects and uncertainty from climate change (DiMento and Ingram 2005; Farber 2007). Such an information infrastructure, combined with a range of incentives that encourage regulators to engage in adaptive management and programmatic adjustment over time (Baron et al. 2009), will help governmental and private institutions become more resilient and capable of managing the physical and human institutional effects of changing climate (Camacho 2009).

Book chapter↗
USGS2019

Conservation of temporary wetlands

Temporary wetlands are characterized by frequent drying resulting in a unique, highly specialized assemblage of often rare or specialized plant and animal species. They are found on all continents and in a variety of landscape settings. Although accurate estimates of the abundance of temporary wetlands are available in only a few countries, global estimations identify a decline in number and quality. The key environmental factors driving the structure of ecological communities in temporary wetlands are the duration, timing, frequency and predictability of the aquatic and dry phases, which varies greatly with region and hydrogeomorphic setting. Temporary wetlands have been historically neglected, but improved social awareness of the functions and values of, and increases in scientific interest, suggest that this is changing. They play an ecological role in both global cycles (i.e., CO 2 emissions) and biodiversity (in proportion to their size, they contribute disproportionately to regional and global biodiversity). Moreover, they provide valuable ecosystem services including wildlife habitat, nutrient flux to adjacent ecosystems, flood control, water filtration, and cultural services. Effective conservation of temporary wetlands requires addressing threats (i.e., inconsistent and inadequate regulatory protections; climate change; changes in land use) and management challenges (i.e., management at both local and landscape scales; incomplete understanding of the ecosystem services provided by them; the need to enhance inventories). The most suitable approaches for conserving temporary wetlands include (1) regulations or other forms of protection; (2) sustainable management; (3) restoration and creation; and (4) collaborative conservation.

Book chapter↗
USGS2005

Nonlinear dynamics in ecosystem response to climatic change: Case studies and policy implications

Many biological, hydrological, and geological processes are interactively linked in ecosystems. These ecological phenomena normally vary within bounded ranges, but rapid, nonlinear changes to markedly different conditions can be triggered by even small differences if threshold values are exceeded. Intrinsic and extrinsic ecological thresholds can lead to effects that cascade among systems, precluding accurate modeling and prediction of system response to climate change. Ten case studies from North America illustrate how changes in climate can lead to rapid, threshold-type responses within ecological communities; the case studies also highlight the role of human activities that alter the rate or direction of system response to climate change. Understanding and anticipating nonlinear dynamics are important aspects of adaptation planning since responses of biological resources to changes in the physical climate system are not necessarily proportional and sometimes, as in the case of complex ecological systems, inherently nonlinear.

Ecological Complexity↗
USGS2016

The automated reference toolset: A soil-geomorphic ecological potential matching algorithm

Ecological inventory and monitoring data need referential context for interpretation. Identification of appropriate reference areas of similar ecological potential for site comparison is demonstrated using a newly developed automated reference toolset (ART). Foundational to identification of reference areas was a soil map of particle size in the control section (PSCS), a theme in US Soil Taxonomy. A 30-m resolution PSCS map of the Colorado Plateau (366,000 km 2 ) was created by interpolating ∼5000 field soil observations using a random forest model and a suite of raster environmental spatial layers representing topography, climate, general ecological community, and satellite imagery ratios. The PSCS map had overall out of bag accuracy of 61.8% (Kappa of 0.54, p < 0.0001), and an independent validation accuracy of 93.2% at a set of 356 field plots along the southern edge of Canyonlands National Park, Utah. The ART process was also tested at these plots, and matched plots with the same ecological sites (ESs) 67% of the time where sites fell within 2-km buffers of each other. These results show that the PSCS and ART have strong application for ecological monitoring and sampling design, as well as assessing impacts of disturbance and land management action using an ecological potential framework. Results also demonstrate that PSCS could be a key mapping layer for the USDA-NRCS provisional ES development initiative.

Soil Science Society of America Journal↗
USGS2018

Vegetation influences on infiltration in Hawaiian soils

Changes in vegetation communities caused by removing trees, introducing grazing ungulates, and replacing native plants with invasive species have substantially altered soil infiltration processes and rates in Hawaii. These changes directly impact run-off, erosion, plant-available water, and aquifer recharge. We hypothesize that broad vegetation communities can be characterized by distributions of field-saturated hydraulic conductivity (Kfs). We used 290 measurements of Kfs calculated from infiltration tests from 5 of the Hawaiian Islands to show this effect. We classified the data using 3 broad ecosystem categories: grasses, trees and shrubs, and bare soil. The soils of each site have coevolved with past and present ecological communities without significant mechanical disturbance by agriculture or urban development. Geometric mean values Kfs are 203 mm/hr for soils hosting trees and shrubs, 50 mm/hr for grasses, and 13 mm/hr for bare soil. Differences are statistically significant at the 95% confidence level. These examples show that it is feasible to make maps of relative Kfs based on field and ecosystem data. These ecosystem trends can be used to estimate ongoing changes to run-off and recharge from climate and land use change. Greater Kfs for ecosystems with primarily trees and shrubs suggests that management decisions concerning reforestation or other changes of vegetation can have substantial hydrologic impacts.

Hawaii↗
USGS2025

When do single-species occupancy models outperform multispecies models?

Occupancy models have become increasingly popular for species monitoring and assessment, in part, because detection/non-detection data are readily obtained using a variety of methods. Multispecies occupancy models (MSOMs) can yield more accurate parameter estimates than single-species models (SSOMs) with less data through their hierarchical structure, making MSOMs an attractive option when species are hard to detect or when data collection is constrained, leading to sparse datasets. Such constraints may arise from limited sampling resources, but also occur in rare species monitoring or where preliminary results are desired to inform adaptive management. Further, experimental habitat treatments often impose spatial constraints on sampling based on the scale of their implementation. Whether a MSOM outperforms SSOMs depends on the volume of data, characteristics of the ecological community, research goals of a study and how these factors align with modeling assumptions. We performed a simulation study of hypothetical pollinator communities under varying sampling intensities for scenarios in which experimental habitat treatments produced different community-level effects. We fit occupancy models to simulated datasets and assessed model performance. At lower sampling intensities (< 20 spatial replicates and < 4 temporal replicates), MSOM community-level treatment effect estimates were biased. Even at twice this sampling intensity, SSOMs yielded more accurate species-specific effect estimates in treatment effect scenarios with high variance. In some cases, MSOMs can pull species in the tails of distributions too far toward the community mean effect, which risks incorrect conclusions concerning whether treatments help or harm individual species. When quantifying species-specific effects is the main objective, particularly for rarely observed species, SSOMs are more robust to outliers across a range of community response scenarios. Researchers can use this information to inform study design, guide simulation studies and decide whether the higher precision of MSOMs outweighs risks of improperly estimated effects for some species.

Ecology and Evolution↗
USGS2025

Parasite‐mediated competition limits dominant cervid competitor

Species interactions structure ecological communities through direct and indirect pathways with ecosystem-wide implications. Despite mounting interest in the importance of indirect interactions, empirical evidence remains limited. Here, we demonstrate the critical role of parasite-mediated competition in driving community outcomes in a multi-species system of conservation and management concern. We leveraged 2 years of detection/non-detection data of moose ( Alces alces ) and white-tailed deer ( Odocoileus virginianus ) and parasite loads in faecal samples within a hierarchical abundance-mediated interaction model to test hypotheses regarding interactions between these cervids and their shared parasites ( Parelaphostrongylus tenuis , Fascioloides magna ). We demonstrate that moose occupancy was limited by parasite-mediated competition, with no evidence of population-level effects of direct competitive interactions between moose and white-tailed deer. Such evidence of the importance of indirect interactions and resulting community outcomes is critical for species conservation and managing range contractions due to increasing pressures from habitat loss, disease and climate change.

New York↗
USGS2008

Book review: The ecology and behavior of amphibians

This state‐of‐the‐art book has made its timely emergence amid a crisis of global magnitude: that of population declines, range reductions, and extinctions of numerous species of amphibians. A clear understanding of the fundamental concepts in amphibian biology is crucial to the success of any conservation effort. This volume compiles the information necessary to acquire that basic understanding. It is a comprehensive synthesis of both traditional and contemporary facets of amphibian biology, spanning a breadth of topics ranging from phylogeny, physiology, behavior, population and community ecology, and conservation. As such, it undoubtedly takes its place among contemporary volumes as the single, authoritative source for basic topics relevant to amphibian life. Review info: The Ecology and Behavior of Amphibians. By Kentwood D. Wells, 2007. ISBN: 978-0-226-89334-1, 1148 pp.

The Quarterly Review of Biology↗
USGS2004

Cannibalism and predation by western toad (Bufo boreas boreas) larvae in Oregon, USA

Larval amphibians have been widely used as model organisms in studies of community ecology of freshwater systems (Morin 1983, Alford 1999). Much of this work has assumed that trophic effects of larval anurans are focused on periphyton and planktonic algae (Dickman 1968, Seale 1980, Duellman and Trueb 1986), a view that has recently been questioned. Recent experiments suggest that anuran larvae can occupy broader trophic roles than previously believed and may function as important predators in some pond communities (Petranka et al. 1994, Petranka and Kennedy 1999)

Oregon↗
USGS2014

Editors are editors, not oracles

Farji-Brener and Kitzberger (2014; hereafter FBK) resurrect the issues of Farji-Brener (2007) concerning manuscripts that are submitted to journals but that are not sent out for peer review: a process we call “reject following editorial review” (RFER). We thank FBK for reviving discussion about this important topic as new challenges, including new publication outlets, peer-review models, and an increasingly complex and voluminous scientific literature, are emerging across the publication landscape. While we disagree with FBK's perspective and conclusions, we recognize that this discussion can help to improve editorial and publication processes, and we welcome the opportunity to inform the ecological community about the current status of editorial practice at ESA journals.

Bulletin of the Ecological Society of America↗