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At least 253 records · Page 14Linked to original sources
USGS1995

National Research Program of the U.S. Geological Survey, Water Resources Division fiscal year 1994

This report provides current information about the National Research Program (NRP) of the U.S. Geological Survey's Water Resources Division (WRD) during fiscal year 1994. Organized by NRP's six research disciplines ecology, geomorphology and sediment transport, ground-water chemistry, ground-water hydrology, surface-water chemistry, and surface-water hydrology the volume contains a summary of the problem, objective, approach, and progress for each project that was active during fiscal year 1994. It also contains bibliographic information that, because of the long-term nature of the program, covers a 5-year period.

Open-File Report↗
USGS2005

A field test of the extent of bias in selection estimates after accounting for emigration

Question: To what extent does trait-dependent emigration bias selection estimates in a natural system? Organisms: Two freshwater cohorts of Atlantic salmon (Salmo salar) juveniles. Field site: A 1 km stretch of a small stream (West Brook) in western Massachusetts. USA from which emigration could be detected continuously. Methods: Estimated viability selection differentials for body size either including or ignoring emigration (include = emigrants survived interval, ignore = emigrants did not survive interval) for 12 intervals. Results: Seasonally variable size-related emigration from our study site generated variable levels of bias in selection estimates for body size. The magnitude of this bias was closely related with the extent of size-dependent emigration during each interval. Including or ignoring the effects of emigration changed the significance of selection estimates in 5 of the 12 intervals, and changed the estimated direction of selection in 4 of the 12 intervals. These results indicate the extent to which inferences about selection in a natural system can be biased by failing to account for trait-dependent emigration. ?? 2005 Benjamin H. Letcher.

Evolutionary Ecology Research↗
USGS2007

A field test of the centrifugal community organization model using psammophilic gerbils in Israel's southern coastal plain

Background: An optimal habitat selection model called centrifugal community organization (CCO) predicts that species, although they have the same primary habitat, may co-exist owing to their ability to use different secondary habitats. Goal: Test the predictions of CCO with field experiments. Species: The Egyptian sand gerbil (40 g), Gerbillus pyramidum, and Allenby's gerbil (25 g), G. andersoni allenbyi. Site: Ashdod sand dunes in the southern coastal plain of Israel. Three sandy habitats are present: shifting, semi-stabilized, and stabilized sand. Gerbils occupied all three habitats. Methods: We surveyed rodent abundance, activity levels, and foraging behaviour while experimentally removing G. pyramidum. Results: Three predictions of the CCO model were supported. Both species did best in the semi-stabilized habitat. However, they differed in their secondary habitats. Gerbillus pyramidum preferred the shifting sand habitat, whereas G. a. allenbyi preferred the stabilized habitat. Habitat selection by both species depended on density. However, in contrast to CCO, G. pyramidum dominated the core habitat and excluded G. a. allenbyi. We term this variant of CCO, 'asymmetric CCO'. Conclusions: The fundamental feature of CCO appears valid: co-existence may result not because of what each competing species does best, but because of what they do as a back-up. But in contrast to the prediction of the original CCO model, all dynamic traces of interaction can vanish if the system includes interference competition. ?? 2007 Gideon Wasserberg.

Evolutionary Ecology Research↗
USGS2009

Learning to be different: Acquired skills, social learning, frequency dependence, and environmental variation can cause behaviourally mediated foraging specializations

Question: How does the ability to improve foraging skills by learning, and to transfer that learned knowledge, affect the development of intra-population foraging specializations? Features of the model: We use both a state-dependent life-history model implemented by stochastic dynamic programming (SDPM) and an individual-based model (IBM) to capture the dynamic nature of behavioural preferences in feeding. Variables in the SDPM include energy reserves, skill levels, energy and handling time per single prey item, metabolic rate, the rates at which skills are learned and forgotten, the effect of skills on handling time, and the relationship between energy reserves and fitness. Additional variables in the IBM include the probability of successful weaning, the logistic dynamics of the prey species with stochastic recruitment, the intensity of top-down control of prey by predators, the mean and variance in skill levels of new recruits, and the extent to which learned Information can be transmitted via matrilineal social learning. Key range of variables: We explore the effects of approaching the time horizon in the SDPM, changing the extent to which skills can improve with experience, increasing the rates of learning or forgetting of skills, changing whether the learning curve is constant, accelerating (T-shaped) or decelerating ('r'-shaped), changing both mean and maximum possible energy reserves, changing metabolic costs of foraging, and changing the rate of encounter with prey. Conclusions: The model results show that the following factors increase the degree of prey specialization observed in a predator population: (1) Experience handling a prey type can substantially improve foraging skills for that prey. (2) There is limited ability to retain complex learned skills for multiple prey types. (3) The learning curve for acquiring new foraging skills is accelerating, or J-shaped. (4) The metabolic costs of foraging are high relative to available energy reserves. (5) Offspring can learn foraging skills from their mothers (matrilineal social learning). (6) Food abundance is limited, such that average individual energy reserves are low Additionally, the following factors increase the likelihood of alternative specializations co-occurring in a predator population: (1) The predator exerts effective top-down control of prey abundance, resulting in frequency-dependent dynamics. (2) There is stochastic Variation in prey population dynamics, but this Variation is neither too extreme in magnitude nor too 'slow' with respect to the time required for an individual forager to learn new foraging skills. For a given predator population, we deduce that the degree of specialization will be highest for those prey types requiring complex capture or handling skills, while prey species that are both profitable and easy to capture and handle will be included in the diet of all individuals. Frequency-dependent benefits of selecting alternative prey types, combined with the ability of foragers to improve their foraging skills by learning, and transmit learned skills to offspring, can result in behaviourally mediated foraging specialization, and also lead to the co-existence of alternative specializations. The extent of such specialization is predicted to be a variable trait, increasing in locations or years when intra-specific competition is high relative to inter-specific competition. ?? 2009 M. Tim Tinker.

Evolutionary Ecology Research↗
USGS2010

Unifying quantitative life-history theory and field endocrinology to assess prudent parenthood in a long-lived seabird

Question: Can field measurements of stress hormones help us to assess the prudent parent hypothesis in a long-lived seabird? Organism: Black-legged kittiwake, Rissa tridactyla . Location: Duck and Gull Islands, Cook Inlet, Alaska, USA. Methods: We examined the statistical relationship between the stress hormone corticosterone and mortality in black-legged kittiwakes. We built a demographic model of the kittiwake life cycle to determine whether the mortality rates associated with persisting in a breeding attempt despite high corticosterone caused the birds to sacrifice more lifetime reproductive output than they gain from one year’s breeding. Results: The probability of apparent mortality increased with corticosterone, suggesting some birds incurred increased mortality risk for the sake of breeding. For Duck Island (low reproductive success), it appears birds sacrificed more lifetime reproductive success than a prudent parent would. On Gull Island, it appears most but possibly not all birds were behaving in ways consistent with theory, although definitive statements require larger samples of highly stressed birds.

Alaska↗
USGS2016

Osmoregulatory physiology and rapid evolution of salinity tolerance in threespine stickleback recently introduced to fresh water

Background: Post-Pleistocene diversification of threespine stickleback in fresh water offers a valuable opportunity to study how changes in environmental salinity shape physiological evolution in fish. In Alaska, the presence of both ancestral oceanic populations and derived landlocked populations, including recent lake introductions, allows us to examine rates and direction of evolution of osmoregulation following halohabitat transition. Hypotheses: Strong selection for enhanced freshwater tolerance will improve survival of recently lake-introduced stickleback in ion-poor conditions compared with their oceanic ancestors. Trade-offs between osmoregulation in fresh water and seawater will allow members of the ancestral population to survive better in response to seawater challenge, as mediated by upregulating salt-secreting transporters in the gill. Poorer hypo-osmoregulatory performance of derived fish will be marked by higher levels of taurine and other organic osmolytes. Methods: We reared clutches at a common salinity from an anadromous and a descendant population, Scout Lake, which has been landlocked for only two generations. We challenged 6-week-old juveniles with extreme low and high salinity treatments and sampled fish over 10 days to investigate putative molecular mechanisms underlying differences in halotolerance. We measured whole-body organic osmolyte content as well as gill Na + /K + -ATPase (NKA) activity and Na + /K + /2Cl − cotransporter (NKCC) protein abundance. Other juveniles from these populations and also from Cheney Lake, a fourth-generation landlocked descendant, were gradually salt-acclimated to determine maximum halotolerance limits. Results: Scout Lake stickleback exhibited 67% higher survival in fresh water than the ancestral anadromous population, but individuals from both groups exhibited similar seawater tolerance. Likewise, the gradual salinity threshold for each population was equivalent (71 ppt). Gill NKA activity and NKCC abundance were both higher in seawater-challenged fish, but did not differ between populations. Sticklebacks from both populations responded to acute salinity stress by transiently increasing osmolyte levels in seawater and decreasing them in fresh water. Conclusion: Enhanced freshwater tolerance has evolved rapidly in recently landlocked stickleback compared with their anadromous ancestors (0.569 haldanes), but the former have retained ancestral seawater-osmoregulatory function.

Evolutionary Ecology Research↗
USGS1978

A paleolimnological comparison of Burntside and Shagawa Lakes, northeastern Minnesota

The paleolimnological records of Burntside and Shagawa Lakes in northeastern Minnesota reveal that these two adjacent lakes have been limnologically distinct for many years prior to the late 19th century activities of white men that polluted Shagawa Lake. Although both lakes occur within the same vegetation type and share much of their water, the diatom stratigraphy of their bottom sediments indicates that Burntside Lake was less productive in its natural state than Shagawa Lake. The causes for this natural difference are not clearly known, but differences in relative size of drainage area and in bedrock geology may he responsible. Intensive white settlement around Shagawa Lake beginning in 1866 supplied nutrients that increased its productivity and finally supported the massive blooms of blue-green algae that characterize culturally eutrophic lakes. Burntside Lake was spared such intensive eutrophication, but its diatom record shows that nutrients derived from shoreside recreational cabins and related construction activity are increasing the lake's productivity. The results of this study show that paleolimnological studies may provide better comparative information for lake rehabilitation programs than do biological and chemical analyses of contemporary unpolluted water bodies.

Minnesota↗
USGS2013

Conservation and Ecology of Marine Forage Fishes--Proceedings of a Research Symposium, September 2012

Locally and globally, there is growing recognition of the critical roles that herring, smelt, sand lance, eulachon, and other forage fishes play in marine ecosystems. Scientific and resource management entities throughout the Salish Sea, agree that extensive information gaps exist, both in basic biological knowledge and parameters critical to fishery management. Communication and collaboration among researchers also is inadequate. Building on the interest and enthusiasm generated by recent forage fish workshops and symposia around the region, the 2012 Research Symposium on the Conservation and Ecology of Marine Forage Fishes was designed to elucidate practical recommendations for science and policy needs and actions, and spur further collaboration in support for the precautionary management of forage fish. This dynamic and productive event was a joint venture of the Northwest Straits Commission Forage Fish Program, U.S. Geological Survey (USGS), Washington Department of Fish and Wildlife (WDFW), and The Puget Sound Partnership. The symposium was held on September 12–14, 2012, at the University of Washington, Friday Harbor Laboratories campus. Sixty scientists, graduate students, and fisheries policy experts convened; showcasing ongoing research, conservation, and management efforts targeting forage fish from regional and national perspectives. The primary objectives of this event were to: (1) review current research and management related to marine forage fish species; and (2) identify priority science and policy needs and actions for Washington, British Columbia, and the entire West Coast. Given the diversity of knowledge, interests, and disciplines surrounding forage fish on both sides of the international border, the organizing committee made a concerted effort to contact many additional experts who, although unable to attend, provided valuable insights and ideas to the symposium structure and discussions. The value of the symposium format was highlighted in the closing remarks delivered by Joseph Gaydos, SeaDoc Society and Chair of the Puget Sound Science Panel. Dr. Gaydos’ presentation referenced the 2011 paper by Murray Rudd in the journal Conservation Biology , “How research-prioritization exercises affect conservation policy.” The paper points out that policy makers and funding agencies are more likely to gain a full understanding of issues when they are presented with research findings from an aligned research program. That is, compared to unaligned research strategies, where work is not based on identified research priorities.

Open-File Report↗
USGS2016

A science of integration: frameworks, processes, and products in a place-based, integrative study

Integrative research is increasingly a priority within the scientific community and is a central goal for the evolving field of sustainability science. While it is conceptually attractive, its successful implementation has been challenging and recent work suggests that the move towards interdisciplinarity and transdisciplinarity in sustainability science is being only partially realized. To address this from the perspective of social-ecological systems (SES) research, we examine the process of conducting a science of integration within the Southcentral Alaska Test Case (SCTC) of Alaska-EPSCoR as a test-bed for this approach. The SCTC is part of a large, 5 year, interdisciplinary study investigating changing environments and adaptations to those changes in Alaska. In this paper, we review progress toward a science of integration and present our efforts to confront the practical issues of applying proposed integration frameworks. We: (1) define our integration framework; (2) describe the collaborative processes, including the co-development of science through stakeholder engagement and partnerships; and (3) illustrate potential products of integrative, social-ecological systems research. The approaches we use can also be applied outside of this particular framework. We highlight challenges and propose improvements for integration in sustainability science by addressing the need for common frameworks and improved contextual understanding. These insights may be useful for capacity-building for interdisciplinary projects that address complex real-world social and environmental problems.

Sustainability Science↗
USGS2015

Progress and challenges in coupled hydrodynamic-ecological estuarine modeling

Numerical modeling has emerged over the last several decades as a widely accepted tool for investigations in environmental sciences. In estuarine research, hydrodynamic and ecological models have moved along parallel tracks with regard to complexity, refinement, computational power, and incorporation of uncertainty. Coupled hydrodynamic-ecological models have been used to assess ecosystem processes and interactions, simulate future scenarios, and evaluate remedial actions in response to eutrophication, habitat loss, and freshwater diversion. The need to couple hydrodynamic and ecological models to address research and management questions is clear because dynamic feedbacks between biotic and physical processes are critical interactions within ecosystems. In this review, we present historical and modern perspectives on estuarine hydrodynamic and ecological modeling, consider model limitations, and address aspects of model linkage, skill assessment, and complexity. We discuss the balance between spatial and temporal resolution and present examples using different spatiotemporal scales. Finally, we recommend future lines of inquiry, approaches to balance complexity and uncertainty, and model transparency and utility. It is idealistic to think we can pursue a “theory of everything” for estuarine models, but recent advances suggest that models for both scientific investigations and management applications will continue to improve in terms of realism, precision, and accuracy.

Estuaries and Coasts↗
USGS2021

Caution is warranted when using animal space-use and movement to infer behavioral states

Background Identifying the behavioral state for wild animals that can’t be directly observed is of growing interest to the ecological community. Advances in telemetry technology and statistical methodologies allow researchers to use space-use and movement metrics to infer the underlying, latent, behavioral state of an animal without direct observations. For example, researchers studying ungulate ecology have started using these methods to quantify behaviors related to mating strategies. However, little work has been done to determine if assumed behaviors inferred from movement and space-use patterns correspond to actual behaviors of individuals. Methods Using a dataset with male and female white-tailed deer location data, we evaluated the ability of these two methods to correctly identify male-female interaction events (MFIEs). We identified MFIEs using the proximity of their locations in space as indicators of when mating could have occurred. We then tested the ability of utilization distributions (UDs) and hidden Markov models (HMMs) rendered with single sex location data to identify these events. Results For white-tailed deer, male and female space-use and movement behavior did not vary consistently when with a potential mate. There was no evidence that a probability contour threshold based on UD volume applied to an individual’s UD could be used to identify MFIEs. Additionally, HMMs were unable to identify MFIEs, as single MFIEs were often split across multiple states and the primary state of each MFIE was not consistent across events. Conclusions Caution is warranted when interpreting behavioral insights rendered from statistical models applied to location data, particularly when there is no form of validation data. For these models to detect latent behaviors, the individual needs to exhibit a consistently different type of space-use and movement when engaged in the behavior. Unvalidated assumptions about that relationship may lead to incorrect inference about mating strategies or other behaviors.

Movement Ecology↗
USGS2009

Methodology for an integrative assessment of China's ecological restoration programs

While research projects have been conducted to examine the impacts and effectiveness of China's ecological restoration programs, few of them represent integrated, systematic efforts. The objective of this chapter is thus to articulate and outline a methodology for an integrative assessment, which, we believe, should embrace both the environmental and socioeconomic changes and engage investigations at multiple scales. Further, these investigations should be pursued through interdisciplinary collaboration with expertise from ecology, economics, hydrology, and geospatial, climate, and land change sciences. We argue that the deployment of geospatial capability, the use of longitudinal data, and the connection between science and policy should be the hallmarks of an integrative assessment. We also describe our general approach and specific models to quantify the environmental and socioeconomic impacts induced by implementing the restoration programs, and address the issue of how to overcome the challenges in generating the data needed for executing various empirical tasks. We hope that the adoption and application of this methodology will make a valuable contribution to a more robust and timely assessment as well as implementation of the ecological restoration programs in and outside of China.

Book chapter↗
USGS2021

Broadening the ecology of fear: Non-lethal effects arise from diverse responses to predation and parasitism

Research on the ‘ecology of fear’ posits that defensive prey responses to avoid predation can cause non-lethal effects across ecological scales. Parasites also elicit defensive responses in hosts with associated non-lethal effects, which raises the longstanding, yet unresolved question of how non-lethal effects of parasites compare with those of predators. We developed a framework for systematically answering this question for all types of predator–prey and host–parasite systems. Our framework reveals likely differences in non-lethal effects not only between predators and parasites, but also between different types of predators and parasites. Trait responses should be strongest towards predators, parasitoids and parasitic castrators, but more numerous and perhaps more frequent for parasites than for predators. In a case study of larval amphibians, whose trait responses to both predators and parasites have been relatively well studied, existing data indicate that individuals generally respond more strongly and proactively to short-term predation risks than to parasitism. Apart from studies using amphibians, there have been few direct comparisons of responses to predation and parasitism, and none have incorporated responses to micropredators, parasitoids or parasitic castrators, or examined their long-term consequences. Addressing these and other data gaps highlighted by our framework can advance the field towards understanding how non-lethal effects impact prey/host population dynamics and shape food webs that contain multiple predator and parasite species.

Proceedings of the Royal Society B↗
USGS2020

Identifying research needs to inform white-nose syndrome management decisions

Ecological understanding of host–pathogen dynamics is the basis for managing wildlife diseases. Since 2008, federal, state, and provincial agencies and tribal and private organizations have collaborated on bat and white‐nose syndrome (WNS) surveillance and monitoring, research, and management programs. Accordingly, scientists and managers have learned a lot about the hosts, pathogen, and dynamics of WNS. However, effective mitigation measures to combat WNS remain elusive. Host–pathogen systems are complex, and identifying ecological research priorities to improve management, choosing among various actions, and deciding when to implement those actions can be challenging. Through a cross‐disciplinary approach, a group of diverse subject matter experts created an influence diagram used to identify uncertainties and prioritize research needs for WNS management. Critical knowledge gaps were identified, particularly with respect to how WNS dynamics and impacts may differ among bat species. We highlight critical uncertainties and identify targets for WNS research. This tool can be used to maximize the likelihood of achieving bat conservation goals within the context and limitations of specific real‐world scenarios.

Conservation Biology↗
USGS2023

Toward conciliation in the habitat fragmentation and biodiversity debate

Landscape-scale conservation planning is urgent given the extent of anthropogenic land-use change and its pervasive impacts on Earth’s biodiversity. However, such efforts are hindered by disagreements over the effects of habitat fragmentation on biodiversity that have persisted since the mid-1970s. We contend that nearly 50 years later, these disagreements have become a locked-in debate characterized by polarized, unproductive discourse and a lack of consistent guidance for landscape managers and policy makers. Here, we highlight the need for a unified set of principles regarding conservation in fragmented landscapes, identify potential reasons for disparate conclusions in fragmentation research, and suggest ways for the ecological community to advance research that leads to consensus rather than the perpetuation of disagreement. Explicit efforts to develop and test multiple competing hypotheses, inter-laboratory collaborations, and acknowledgement of multiple interacting effects will be vital for moving the fragmentation debate forward. We argue that we in the ecology community should be responsible for helping to reconcile different views across scales, systems, and methodological approaches to advance conservation planning within a landscape ecology framework.

Landscape Ecology↗
USGS2017

Book review: Behavioral ecology of the eastern red-backed salamander: 50 years of research

In commemoration of the 100th anniversary of the British Ecological Society, Sutherland et al. (2013) identified 100 questions of fundamental significance in “pure” (i.e., not applied) ecology. A somewhat unexpected outcome of these authors’ exercise was the realization that, after 100 years of comprehensive, intensive scientific research, there remained “profound knowledge gaps” in ecology, such as a clear understanding of “the central mechanisms driving ecosystems…communities…, and even population dynamics.” Animal behavior (along with other attributes such as physiology and genetics) is such a mechanism that can structure ecological interactions, and the study of behavioral ecology provides important insights into many fundamental ecological phenomena. For example, the well-known historical characterization of ecology as the study of the distribution and abundance of organisms (Andrewartha and Birch 1954) invokes numerous questions, such as: what factors influence coexistence among competing species, or between predators and their prey? Ultimately, the answers to these and other questions are best addressed with fine-scale, mechanistic studies of habitat selection, foraging behavior/prey selection, and movement/dispersal behavior. Similarly, at the population level, insight into the spatial distribution of individuals could be gained with studies of territoriality, dominance hierarchies, and even mate choice.

Herpetological Review↗
USGS2014

Standardized phenology monitoring methods to track plant and animal activity for science and resource management applications

Phenology offers critical insights into the responses of species to climate change; shifts in species’ phenologies can result in disruptions to the ecosystem processes and services upon which human livelihood depends. To better detect such shifts, scientists need long-term phenological records covering many taxa and across a broad geographic distribution. To date, phenological observation efforts across the USA have been geographically limited and have used different methods, making comparisons across sites and species difficult. To facilitate coordinated cross-site, cross-species, and geographically extensive phenological monitoring across the nation, the USA National Phenology Network has developed in situ monitoring protocols standardized across taxonomic groups and ecosystem types for terrestrial, freshwater, and marine plant and animal taxa. The protocols include elements that allow enhanced detection and description of phenological responses, including assessment of phenological “status”, or the ability to track presence–absence of a particular phenophase, as well as standards for documenting the degree to which phenological activity is expressed in terms of intensity or abundance. Data collected by this method can be integrated with historical phenology data sets, enabling the development of databases for spatial and temporal assessment of changes in status and trends of disparate organisms. To build a common, spatially, and temporally extensive multi-taxa phenological data set available for a variety of research and science applications, we encourage scientists, resources managers, and others conducting ecological monitoring or research to consider utilization of these standardized protocols for tracking the seasonal activity of plants and animals.

International Journal of Biometeorology↗