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USGS2010

Microbial ecology of corals, sponges, and algae in mesophotic coral environments

Mesophotic coral ecosystems that occur at depths from 30 to 200 m have historically been understudied and yet appear to support a diverse biological community. The microbiology of these systems is particularly poorly understood, especially with regard to the communities associated with corals, sponges, and algae. This lack of information is partly due to the problems associated with gaining access to these environments and poor reproducibility across sampling methods. To summarize what is known about the microbiology of these ecosystems and to highlight areas where research is urgently needed, an overview of the current state of knowledge is presented. Emphasis is placed on the characterization of microbial populations, both prokaryotic and eukaryotic, associated with corals, sponges, and algae and the factors that influence microbial community structure. In topic areas where virtually nothing is known from mesophotic environments, the knowledge pertaining to shallow-water ecosystems is summarized to provide a starting point for a discussion on what might be expected in the mesophotic zone.

FEMS Microbiology Ecology↗

USGS2026

How Indigenous socio-cultural systems resist, accept, or direct ecological transformation: A research agenda

Anthropogenic ecological transformations are challenging conventional environmental management paradigms, as maintaining historical ecological structures and functions becomes increasingly untenable. The resist–accept–direct (RAD) framework offers a strategic tool to navigate these shifts. However, as a product of the dominant socio-cultural system, the RAD framework risks perpetuating the same patterns of thinking that have contributed to unsustainable social-ecological dynamics. Indigenous socio-cultural systems, considered here through the lens of long-term coevolution with their environments, offer valuable empirical models for adaptive responses to environmental change. Such Indigenous socio-cultural responses, grounded in narratives, governance institutions, value systems, and other cultural elements collectively referred to as Indigenous Knowledge (IK), hold relevance for addressing today’s intertwined environmental and social challenges. We provide a targeted review of existing literature at the intersection of IK and the RAD framework, along with a broader conceptual overview of relevant insights across related fields. These reveal contrasting assumptions about Indigenous responses to environmental change, such as consistently resisting to preserve cultural fidelity or uniformly accepting, reflecting deeper cultural, temporal, and ecological complexity. We propose a structured research agenda to investigate Indigenous socio-cultural responses to environmental change through empirical research, theoretical synthesis, hypothesis development, and practical application. This agenda is grounded in comprehensive collaboration, emphasizing shared power and integrating both emic and etic perspectives throughout all stages of research and implementation. By bridging the adaptive dynamics of coevolved social-ecological systems and mainstream management strategies, an IK–RAD framework could enhance the efficacy of responses to global environmental change.

Human Ecology↗

USGS2017

Used-habitat calibration plots: A new procedure for validating species distribution, resource selection, and step-selection models

“Species distribution modeling” was recently ranked as one of the top five “research fronts” in ecology and the environmental sciences by ISI's Essential Science Indicators (Renner and Warton 2013), reflecting the importance of predicting how species distributions will respond to anthropogenic change. Unfortunately, species distribution models (SDMs) often perform poorly when applied to novel environments. Compounding on this problem is the shortage of methods for evaluating SDMs (hence, we may be getting our predictions wrong and not even know it). Traditional methods for validating SDMs quantify a model's ability to classify locations as used or unused. Instead, we propose to focus on how well SDMs can predict the characteristics of used locations. This subtle shift in viewpoint leads to a more natural and informative evaluation and validation of models across the entire spectrum of SDMs. Through a series of examples, we show how simple graphical methods can help with three fundamental challenges of habitat modeling: identifying missing covariates, non-linearity, and multicollinearity. Identifying habitat characteristics that are not well-predicted by the model can provide insights into variables affecting the distribution of species, suggest appropriate model modifications, and ultimately improve the reliability and generality of conservation and management recommendations.

Ecography↗

USGS2013

The overlooked terrestrial impacts of mountaintop mining

Ecological research on mountaintop mining has been focused on aquatic impacts because the overburden (i.e., the mountaintop) is disposed of in nearby valleys, which leads to a wide range of water-quality impacts on streams. There are also numerous impacts on the terrestrial environment from mountaintop mining that have been largely overlooked, even though they are no less wide ranging, severe, and multifaceted. We review the impacts of mountaintop mining on the terrestrial environment by exploring six broad themes: (1) the loss of topographic complexity, (2) forest loss and fragmentation, (3) forest succession and soil loss, (4) forest loss and carbon sequestration, (5) biodiversity, and (6) human health and well-being.

BioScience↗

USGS2006

Show me the numbers: What data currently exist for non-native species in the USA?

Non-native species continue to be introduced to the United States from other countries via trade and transportation, creating a growing need for early detection and rapid response to new invaders. It is therefore increasingly important to synthesize existing data on non-native species abundance and distributions. However, no comprehensive analysis of existing data has been undertaken for non-native species, and there have been few efforts to improve collaboration. We therefore conducted a survey to determine what datasets currently exist for non-native species in the US from county, state, multi-state region, national, and global scales. We identified 319 datasets and collected metadata for 79% of these. Through this study, we provide a better understanding of extant non-native species datasets and identify data gaps (ie taxonomic, spatial, and temporal) to help guide future survey, research, and predictive modeling efforts.

Frontiers in Ecology and the Environment↗

USGS2005

Ecohydrological control of deep drainage in arid and semiarid regions

The amount and spatial distribution of deep drainage (downward movement of water across the bottom of the root zone) and groundwater recharge affect the quantity and quality of increasingly limited groundwater in arid and semiarid regions. We synthesize research from the fields of ecology and hydrology to address the issue of deep drainage in arid and semiarid regions. We start with a recently developed hydrological model that accurately simulates soil water potential and geochemical profiles measured in thick (>50 m), unconsolidated vadose zones. Model results indicate that, since the climate change that marked the onset of the Holocene period 10 000–15 000 years ago, there has been no deep drainage in vegetated interdrainage areas and that continuous, relatively low (<−1 MPa) soil water potentials have been maintained at depths of 2–3 m. A conceptual model consistent with these results proposes that the native, xeric‐shrub‐dominated, plant communities that gained dominance during the Holocene generated and maintained these conditions. We present three lines of ecological evidence that support the conceptual model. First, xeric shrubs have sufficiently deep rooting systems with low extraction limits to generate the modeled conditions. Second, the characteristic deep‐rooted soil–plant systems store sufficient water to effectively buffer deep soil from climatic fluctuations in these dry environments, allowing stable conditions to persist for long periods of time. And third, adaptations resulting in deep, low‐extraction‐limit rooting systems confer significant advantages to xeric shrubs in arid and semiarid environments. We then consider conditions in arid and semiarid regions in which the conceptual model may not apply, leading to the expectation that portions of many arid and semiarid watersheds supply some deep drainage. Further ecohydrologic research is required to elucidate critical climatic and edaphic thresholds, evaluate the role of important physiological processes (such as hydraulic redistribution), and evaluate the role of deep roots in terms of carbon costs, nutrient uptake, and whole‐plant development.

Ecology↗

USGS2003

[Book Review] Biology of marine birds

A text devoted to the biology and ecology of marine birds has not been published in the last 15 years. Although a number of more taxa-specific texts have been produced during that period, there has not been a single publication that attempted to review our knowledge of all the major seabird orders since the works of Nelson (1979), Croxall (1987), and Furness and Monaghan (1987). Following the publication of those works, a large and impressive body of literature has been produced. Given the rapid expansion of the field in the last two decades, the time was ripe for production of an extensive compendium on the biology, ecology, and conservation of the world's seabirds. E. A. Schreiber and J. Burger are editors of this CRC publication, Biology of Marine Birds . The book consists of 19 chapters that vary in length from 15 to 51 pages. There are also two extensive appendices: (1) a list of seabird species (restricted to the orders Sphenisciformes, Procellariiformes, Pelecaniformes, and Charadriiformes, the latter limited to Stercorariidae, Laridae, Rhynchopidae, and Alcidae) and their IUCN status, and (2) a very useful table of species-specific life-history traits. The 19 chapters were prepared by 26 authors, among them some of the most respected and published seabird scientists in the world. A brief preface introduces the book, its objective (to provide an examination and summary of the research on seabirds), its audience (researchers, conservationists, managers, and policy-makers), and the taxa covered. The editors coauthored the introductory chapter, Seabirds in the Marine Environment. The authors describe distinctive characteristics of seabird life-histories in comparison to other taxa, hypotheses for why those lifestyles evolved and the potential role of energy limitation in the evolution of seabird life-histories. Along with a discussion of other common seabird traits, such as a propensity for colonial breeding, the authors also suggest directions for future research in seabird ecology.

The Auk↗

USGS2016

Panarchy use in environmental science for risk and resilience planning

Environmental sciences have an important role in informing sustainable management of built environments by providing insights about the drivers and potentially negative impacts of global environmental change. Here, we discuss panarchy theory, a multi-scale hierarchical concept that accounts for the dynamism of complex socio-ecological systems, especially for those systems with strong cross-scale feedbacks. The idea of panarchy underlies much of system resilience, focusing on how systems respond to known and unknown threats. Panarchy theory can provide a framework for qualitative and quantitative research and application in the environmental sciences, which can in turn inform the ongoing efforts in socio-technical resilience thinking and adaptive and transformative approaches to management.

Environment Systems and Decisions↗

USGS2010

North American osprey populations and contaminants: Historic and contemporary perspectives

Osprey ( Pandion haliaetus ) populations were adversely affected by DDT and perhaps other contaminants in the United States and elsewhere. Reduced productivity, eggshell thinning, and high DDE concentrations in eggs were the signs associated with declining osprey populations in the 1950s, 1960s, and 1970s. The species was one of the first studied on a large scale to bring contaminant issues into focus. Although few quantitative population data were available prior to the 1960s, many osprey populations in North America were studied during the 1960s and 1970s with much learned about basic life history and biology. This article reviews the historical and current effects of contaminants on regional osprey populations. Breeding populations in many regions of North America showed post-DDT-era (1972) population increases of varying magnitudes, with many populations now appearing to stabilize at much higher numbers than initially reported in the 1970s and 1980s. However, the magnitude of regional population increases in the United States between 1981 (first Nationwide Survey, ∼8,000 pairs), when some recovery had already occurred, 1994 (second survey, ∼14,200), and 2001 (third survey, ∼16,000–19,000), or any other years, is likely not a simple response to the release from earlier contaminant effects, but a response to multi-factorial effects. This indirect “contaminant effects” measurement comparing changes (i.e., recovery) in post-DDT-era population numbers over time is probably confounded by changing human attitudes toward birds of prey (shooting, destroying nests, etc.), changing habitats, changing fish populations, and perhaps competition from other species. The species' adaptation to newly created reservoirs and its increasing use of artificial nesting structures (power poles, nesting platforms, cell towers, channel markers, offshore duck blinds, etc.) are two important factors. The timing of the initial use of artificial nesting structures, which replaced declining numbers of suitable trees at many locations, varied regionally (much later in the western United States and Mexico). Because of the increasing use of artificial nesting structures, there may be more ospreys nesting in North America now than ever before. Now, with the impact of most legacy organic contaminants (DDT, other organochlorine [OC] pesticides, polychlorinated biphenyls [PCB], polychlorinated dibenzo- p -dioxins [PCDD], polychlorinated dibenzofurans (PCDF]) greatly reduced or eliminated, and some osprey populations showing evidence of stabilizing, the species was proposed as a Worldwide Sentinel Species for evaluating emerging contaminants. Several emerging contaminants are already being studied, such as polybrominated diphenyl ethers (PBDE) and perfluorinated acids and sulfonate compounds (PFC). The many advantages for continued contaminant investigations using the osprey include a good understanding of its biology and ecology, its known distribution and abundance, and its ability to habituate to humans and their activities, which permits nesting in some of the potentially most contaminated environments. It is a top predator in most ecosystems, and its nests are relatively easy to locate and study with little researcher impact on reproductive success.

Journal of Toxicology and Environmental Health, Pa↗

USGS2023

Integrated analysis shows how the effects of extreme flooding events propagate through fish communities to impact amphibians

Research Highlight: Davis, C. L., Walls, S. C., Barichivich, W. J., Brown, M. E., & Miller, D. A. (2022). Disentangling direct and indirect effects of extreme events on coastal wetland communities. Journal of Animal Ecology , https://doi.org/10.1111/1365-2656.13874 . Catastrophic events such as floods, hurricanes, winter storms, droughts and wildfires increasingly touch our lives either directly or indirectly. These events draw our attention to the seriousness of changes in climate not only to human well-being but also to the integrity of ecological systems upon which we depend. Understanding the impacts of extreme events on ecological systems requires the ability to characterize the cascading effects of environmental changes on the environments in which organisms live and the altered biological interactions produced. This scientific ambition represents no small challenge for the study of animal communities, which are typically difficult to census as well as dynamic in time and space. Davis et al. (2022) in a recent study in the Journal of Animal Ecology examined the amphibian and fish communities found in depressional coastal wetlands to better understand how they respond to major rainfall and flooding events. Data from the U.S. Geological Survey's Amphibian Research and Monitoring Initiative provided an 8-year record of observations as well as environmental measurements. For this study, the authors integrated techniques for assessing the dynamics of animal populations with a Bayesian implementation of structural equation modelling. Using their integrated methodological approach permitted the authors to reveal the direct and indirect effects of extreme weather events on co-occurring amphibian and fish communities while accounting for observational uncertainty and temporal variation in population-level processes. Their findings indicate that the most prominent effects of flooding on the amphibian community were caused by changes in the fish community that led to increased predation and resource competition. In their conclusions, the authors emphasize the importance of understanding networks of abiotic and biotic effects if we are to predict and mitigate the influence of extreme weather events.

Journal of Animal Ecology↗

USGS2015

Legacy effects in linked ecological-soil-geomorphic systems of drylands

A legacy effect refers to the impacts that previous conditions have on current processes or properties. Legacies have been recognized by many disciplines, from physiology and ecology to anthropology and geology. Within the context of climatic change, ecological legacies in drylands (eg vegetative patterns) result from feedbacks between biotic, soil, and geomorphic processes that operate at multiple spatial and temporal scales. Legacy effects depend on (1) the magnitude of the original phenomenon, (2) the time since the occurrence of the phenomenon, and (3) the sensitivity of the ecological–soil–geomorphic system to change. Here we present a conceptual framework for legacy effects at short-term (days to months), medium-term (years to decades), and long-term (centuries to millennia) timescales, which reveals the ubiquity of such effects in drylands across research disciplines.

Frontiers in Ecology and the Environment↗

USGS2015

Spatial and temporal variation in marine birds in the north Gulf of Alaska: The value of marine bird monitoring within Gulf Watch Alaska

Birds offer useful insights into marine ecosystems. Marine birds are responsive to spatial and temporal variation in the environment, that often originates with fluctuations in oceanographic and climatic drivers and permeates up through food webs to conspicuous top predators such as seabirds (Coyle and Pinchuk 2005, Speckman et al. 2005, Gonzales-Solis et al. 2009, Cushing et al., this report). In that way, marine birds are excellent assimilators, samplers, and indicators of the status of marine environments (Montevecchi 1993, Piatt et al. 2007b, Zador et al. 2013). Marine bird responses to dynamic marine ecosystems can be detected in a variety of metrics, including abundance, distribution, and productivity. For example, in the northern Gulf of Alaska (GOA), decadal-scale variation in oceanographic conditions has been associated with dramatic shifts in prey composition and abundance (Anderson and Piatt 1999). In turn, these shifts were more closely correlated with changes in abundance of fish-eating birds of Prince William Sound (PWS), such as pigeon guillemots (Golet et al. 2002) and marbled and Kittlitz’s murrelets (Kuletz et al. 2011a, 2011b), than in the abundance of species that primarily consume plankton or benthic prey (Agler et al. 1999, Cushing et al., this report). Birds also are responsive to anthropogenic influences in marine environments, including commercial fishing, contamination, introduction of non-native species, coastal development, offshore resource extraction, and vessel traffic. A major anthropogenic perturbation in the northern GOA was the 1989 Exxon Valdez oil spill, in which marine birds suffered high immediate mortality (Piatt and Ford 1996). Additionally, several species showed long-term evidence of declines in the oiled areas of PWS (Lance et al. 2001), as well as impacts to reproductive success years later (Golet et al. 2002). However, the degree of direct impact and vulnerability to chronic injury, which was related to exposure to lingering oil, varied widely among species (see Esler et al., this report). Research and monitoring directed at documenting the timelines and mechanisms of wildlife recovery following the Exxon Valdez oil spill led to an unprecedented understanding of oil spill effects on marine birds, as well as previously unknown information about marine bird ecology in the northern GOA. Quantifying effects of anthropogenic influences requires an understanding of variation in marine bird abundance, distribution, and productivity, in relation to naturally occurring dynamics in marine environments continued marine bird work as part of Gulf Watch Alaska will facilitate this. In addition to their value as indicators of marine conditions and anthropogenic influences, marine birds are protected under the Migratory Bird Treaty Act and are managed by the U.S. Fish and Wildlife Service (USFWS). Marine birds have high societal value from a wide variety of interests (e.g., tourism, bird watching, hunting, mythology), and are an important source of subsistence foods in Alaska (Naves and Braem 2014). Because of the conservation interest in marine birds, as well as their value for indicating the status of marine ecosystems, monitoring of marine birds is an important component of many ocean monitoring programs, including Gulf Watch Alaska.

Alaska↗

USGS2001

The environment and human health; USGS science for solutions

Emerging infectious diseases, ground-water contamination, trace-metal poisoning...environmental threats to public health the world over require new solutions. Because of an increased awareness of the issues, greater cooperation among scientific and policy agencies, and powerful new tools and techniques to conduct research, there is new hope that complex ecological health problems can be solved. U.S. Geological Survey scientists are forming partnerships with experts in the public health and biomedical research communities to conduct rigorous scientific inquiries into the health effects of ecological processes.

Fact Sheet↗

USGS2025

Microbial ecology of permafrost soils: Populations, processes, and perspectives

Permafrost microbial research has flourished in the past decades, due in part to improvements in sampling and molecular techniques, but also the increased focus on the permafrost greenhouse gas feedback to climate change and other ecological processes in high latitude and alpine permafrost soils. Permafrost microorganisms are adapted to these extreme environments and remain active at low temperatures and when resources are limited. They are also an important component of global elemental cycles as they regulate organic matter turnover and greenhouse gas production, particularly as permafrost thaws. Here we review the permafrost microbiology literature coupled with an exploration of its historical aspects, with a particular focus on a new understanding advanced by molecular biology techniques. We further identify knowledge gaps and ways forward to improve our understanding of microbial contributions to ecosystem biogeochemistry of permafrost-affected systems.

Permafrost and Periglacial Processes↗

USGS1985

Environmental systems and management activities on the Kennedy Space Center, Merritt Island, Florida: results of a modeling workshop

In the early 1960's, the National Aeronautics and Space Administration (NASA) began purchasing 140,000 acres on Merritt Island, Florida, in order to develop a center for space exploration. Most of this land was acquired to provide a safety and security buffer around NASA facilities. NASA, as the managing agency for the Kennedy Space Center (KSC), is responsible for preventing or controlling environmental pollution from the Federal facilities and activities at the Space Center and is committed to use all practicable means to protect and enhance the quality of the surrounding environment. The Merritt Island National Wildlife Refuge was established in 1963 when management authority for undeveloped lands at KSC was transferred to the U.S. Fish and Wildlife Service. In addition to manage for 11 Federally-listed threatened and endangered species and other resident and migratory fish and wildlife populations, the Refuge has comanagement responsibility for 19,000 acres of mosquito control impoundments and 2,500 acres of citrus groves. The Canaveral National Seashore was developed in 1975 when management of a portion of the coastal lands was transferred from NASA to the National Park Service. This multiagency jurisdiction on Merritt Island has resulted in a complex management environment. The modeling workshop described in this report was conducted May 21-25, 1984, at the Kennedy Space Center to: (1) enhance communication among the agencies with management responsibilities on Merritt Island; (2) integrate available information concerning the development, management, and ecology of Merritt Island; and (3) identify key research and monitoring needs associated with the management and use of the island's resources. The workshop was structured around the formulation of a model that would simulate primary management and use activities on Merritt Island and their effects on upland, impoundment, and estuarine vegetation and associated wildlife. The simulation model is composed of four connected submodels. The Uplands submodel calculates changes in acres and structural components of vegetation communities resulting from succession, fire, facilities development, and shuttle launch depositions, as well as the quantity and quality of surface runoff and aquifer input to an impoundment and an estuary. The Impoundment submodel next determines water quality and quantity and changes in vegetation resulting from water level manipulation and prescribed burning. The Estuary submodel than determines water quality parameters and acres of seagrass beds. Finally, the Wildlife submodel calculates habitat suitability indices for key species of interest, based on vegetation conditions in the uplands and impoundments and on several hydrologic parameters. The model represents a hypothetical management unit with 2,500 acres of uplands, a 600-acre impoundment, and a 1,500-acre section of estuary. Two management scenarios were run to analyze model behavior. The scenarios differ in the frequency of shuttle launches and prescribed burning, the extent of facilities development, the amount of land disposed waste material applied, and the nature and timing of impoundment water level control. Early in a model development project, the process of building the model is usually of greater benefit than the model itself. The model building process stimulates interaction among agencies, assists in integrating existing information, and helps identify research needs. These benefits usually accrue even in the absence of real predictive power in the resulting model. Open communication occurs among the Federal, State, and local agencies involved with activities on Merritt Island and the agencies have a cooperative working relationship. The workshop provided an opportunity for all of these agencies to meet at one time and have focused discussions on the key environmental and multiagency resource management issues. The workshop framework helped to integrate information and assumptions from a number of disciplines and agencies. This integration occurred in the computer simulation model and among workshop participants as submodel linkages were developed and scenario results discussed. A number of research needs were identified at the workshop during the model building and testing exercises and associated discussions. These needs were based on the informed judgement of researchers and managers familiar with Merritt Island or similar areas, rather than on a comprehensive literature review of sensitivity analysis of the preliminary model developed at the workshop. Some of the needs can be addressed by interpreting the results of completed studies from similar geographic areas as they relate to Merritt Island, while other will require additional research studies on Merritt Island. Major research needs associated with the Upland submodel include behavior of the near-surface aquifer, factors limiting slash pine regeneration, frequency and effects of natural fire on various cover types, cumulative effects of shuttle launches, and fate in upland soils of nitrogen and phosphorous from land applied waste material. Key Impoundment submodel needs include documentation of vegetation changes in response to altered water depth, salinity, and nutrient concentrations and better specification of the functional characteristics of impoundments as chemical filters. Important information gaps identified in the Estuary submodel include a more complete analysis of factors contributing to phytoplankton abundance, evaluation of sources of turbidity other than phytoplankton, and identification and quantification of factors limiting seagrass distribution. Primary research needs associated with the Wildlife submodel include a survey of breeding habitat, production data, and harvest data for mottled ducks; data on the emigration and immigration of juvenile mullet (and other transient fish) in the impoundment; the contribution of various seagrasses to habitat requirements of sea trout; and the effects of dissolved oxygen on survival of juvenile sea trout. Ideally, the modeling workshop process is iterative in nature. Periods between workshops are used for research, data collection, and model refinement. Each workshop integrates information collected since the last workshop and produces a more credible model that is more useful in evaluating management alternatives. Participants felt that continued application of this process would help provide ongoing integration and communication among agencies and would allow each agency's planning and management activities to be viewed within the context of an overall assessment.

Report↗

USGS2015

Evaluating the status of individuals and populations: Advantages of multiple approaches and time scales

The assessment of population status is a central goal of applied wildlife research and essential to the field of wildlife conservation. “Population status” has a number of definitions, the most widely used having to do with the current trajectory of the population (i.e., growing, stable, or declining), or the probability of persistence (i.e., extinction risk), perhaps without any specific knowledge as to the factors driving a population’s dynamics. In contrast, a population’s status relative to the carrying capacity of the environment ( K ) is an ecologically-based definition that explicitly provides information about a major mechanism of population control. That is, it relates to the relative per capita availability of resources to individuals in a population, which can also be used to infer the state of the environment itself. Sea otters in the North Pacific provide an excellent system with which to examine various approaches to assessing population status relative to K . This is because sea otters were nearly extirpated by historic commercial overexploitation in the eighteenth and nineteenth centuries, followed by natural and translocation-aided population recovery during the twentieth century, and this decline and recovery has been relatively well documented. This provided a unique opportunity to study populations at the extremes of the population status spectrum. Here we describe and review the approaches that have been utilized in sea otter research to understand the status of populations relative to resource abundance. Specifically, we will illustrate the utility of various indices of population status for understanding population dynamics using the case study of a second precipitous sea otter decline in the Western Aleutians. The indices or “tools” described here fit into several broad categories including (1) energetic, (2) morphological, and (3) demographic as well as a fourth category of emerging tools that have not yet been employed in many other situations including dietary diversity, community structure, spatial distribution, and gene expression. Overall, a variety of indices used to measure population status throughout the sea otter’s range have provided insights for understanding the mechanisms driving the trajectory of various sea otter populations, which a single index could not, and we suggest using multiple methods to measure a population’s status at multiple spatial and temporal scales. The work described here also illustrates the usefulness of long-term data sets and/or approaches that can be used to assess population status retrospectively, providing information otherwise not available. While not all systems will be as amenable to using all the approaches presented here, we expect innovative researchers could adapt analogous multi-scale methods to a broad range of habitats and species including apex predators occupying the top trophic levels, which are often of conservation concern.

Book chapter↗

USGS2005

Performance of four turbulence closure models implemented using a generic length scale method

A two-equation turbulence model (one equation for turbulence kinetic energy and a second for a generic turbulence length-scale quantity) proposed by Umlauf and Burchard [J. Marine Research 61 (2003) 235] is implemented in a three-dimensional oceanographic model (Regional Oceanographic Modeling System; ROMS v2.0). These two equations, along with several stability functions, can represent many popular turbulence closures, including the k-kl (Mellor-Yamada Level 2.5), k-??, and k-?? schemes. The implementation adds flexibility to the model by providing an unprecedented range of turbulence closure selections in a single 3D oceanographic model and allows comparison and evaluation of turbulence models in an otherwise identical numerical environment. This also allows evaluation of the effect of turbulence models on other processes such as suspended-sediment distribution or ecological processes. Performance of the turbulence models and sediment-transport schemes is investigated with three test cases for (1) steady barotropic flow in a rectangular channel, (2) wind-induced surface mixed-layer deepening in a stratified fluid, and (3) oscillatory stratified pressure-gradient driven flow (estuarine circulation) in a rectangular channel. Results from k-??, k-??, and gen (a new closure proposed by Umlauf and Burchard [J. Marine Research 61 (2003) 235]) are very similar for these cases, but the k-kl closure results depend on a wall-proximity function that must be chosen to suit the flow. Greater variations appear in simulations of suspended-sediment concentrations than in salinity simulations because the transport of suspended-sediment amplifies minor variations in the methods. The amplification is caused by the added physics of a vertical settling rate, bottom stress dependent resuspension, and diffusive transport of sediment in regions of well mixed salt and temperature. Despite the amplified sensitivity of sediment to turbulence models in the estuary test case, the four closures investigated here all generated estuarine turbidity maxima that were similar in their shape, location, and concentrations.

Ocean Modelling↗

USGS2013

Climate-change impacts on ecological systems: Introduction to a US assessment

As part of the 2014 US National Climate Assessment, over 60 subject‐matter experts from government agencies, academia, nongovernmental organizations, and the private sector assessed the current and projected impacts of climate change on ecosystems, biodiversity, and ecosystem services. Here, we introduce and provide context for the papers included in this Special Issue, drawing upon the key findings from separate assessments of biodiversity, ecosystem structure and function, ecosystem services, climate‐change impacts in the context of other stressors, and societal responses to change (ie climate adaptation). We also explain the assessment process and show how the current state of knowledge can be used to identify risks and guide future research and management initiatives.

Frontiers in Ecology and the Environment↗