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At least 523 records · Page 29Linked to original sources
USGS2010

Assessment and management of ecological integrity: Chapter 12

Assessing and understanding the impacts of human activities on aquatic ecosystems has long been a focus of ecologists, water resources managers, and fisheries scientists. While traditional fisheries management focused on single-species approaches to enhance fish stocks, there is a growing emphasis on management approaches at community and ecosystem levels. Of course, as fisheries managers shift their attention from narrow (e.g., populations) to broad organizational scales (e.g., communities or ecosystems), ecological processes and management objectives become more complex. At the community level, fisheries managers may strive for a fish assemblage that is complex, persistent, and resilient to disturbance. Aquatic ecosystem level objectives may focus on management for habitat quality and ecological processes, such as nutrient dynamics, productivity, or trophic interactions, but a long-term goal of ecosystem management may be to maintain ecological integrity. However, human users and social, economic, and political demands of fisheries management often result in a reduction of ecological integrity in managed systems, and this conflict presents a principal challenge for the modern fisheries manager. The concepts of biotic integrity and ecological integrity are being applied in fisheries science, natural resource management, and environmental legislation, but explicit definitions of these terms are elusive. Biotic integrity of an ecosystem may be defined as the capability of supporting and maintaining an integrated, adaptive community of organisms having a species composition, diversity, and functional organization comparable to that of a natural habitat of the region (Karr and Dudley 1981). Following that, ecological integrity is the summation of chemical, physical, and biological integrity. Thus, the concept of ecological integrity extends beyond fish and represents a holistic approach for ecosystem management that is especially applicable to aquatic systems. The more general term, ecological condition, refers to the state of the physical, chemical, and biological characteristics of the environment and the processes and interactions that connect them. While the concept of ecological integrity may appear unambiguous, its assessment and practice are much less clear. Ecological integrity made its debut in the USA with the Clean Water Act (CWA) of 1972 (Federal Water Pollution Control Act, as amended through Public Law 107–303, November 27, 2002), which states only one objective, “to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.” This legislation compelled resource managers to focus on chemical pollution from point effluent sources, such as industrial and municipal outflows, as well as give attention to diffuse, chronic, and watershed effects on ecological integrity. Further, the CWA allowed pursuit of restoration programs in degraded water bodies and catalyzed the science and practice of restoration ecology. The term ecosystem health is often raised in discussions of ecological integrity. Perhaps it is natural to anthropomorphize our concern for personal health to ecosystems, so it becomes a useful metaphor for understanding the concept of ecological integrity. However, whether or not an ecosystem should be considered an entity, such as a superorganism, is a debate without end that began with early ecologists and continues today (Clements 1916; Suter 1993; Simon 1999a). Regardless, the ecosystem is indeed a natural unit with a level of organization and properties beyond the collection of those species that occupy it and presents the most appropriate spatial and organizational scale in which to assess and study ecological integrity. Streams and rivers serve as integrators of chemical, physical, and biological conditions across the landscape, and while the theory and practice associated with ecological integrity of aquatic systems is easily applied to flowing waters and is emphasized in this chapter, they are broadly applicable among all aquatic systems.

Book chapter↗
USGS2021

Regional-scale variability in the movement ecology of marine fishes revealed by an integrative acoustic tracking network

Marine fish movement plays a critical role in ecosystem functioning and is increasingly studied with acoustic telemetry. Traditionally, this research has focused on single species and small spatial scales. However, integrated tracking networks, such as the Integrated Tracking of Aquatic Animals in the Gulf of Mexico (iTAG) network, are building the capacity to monitor multiple species over larger spatial scales. We conducted a synthesis of passive acoustic monitoring data for 29 species (889 transmitters), ranging from large top predators to small consumers, monitored along the west coast of Florida, USA, over 3 yr (2016-2018). Space use was highly variable, with some groups using all monitored areas and others using only the area where they were tagged. The most extensive space use was found for Atlantic tarpon Megalops atlanticus and bull sharks Carcharhinus leucas . Individual detection patterns clustered into 4 groups, ranging from occasionally detected long-distance movers to frequently detected juvenile or adult residents. Synchronized, alongshore, long-distance movements were found for Atlantic tarpon, cobia Rachycentron canadum , and several elasmobranch species. These movements were predominantly northbound in spring and southbound in fall. Detections of top predators were highest in summer, except for nearshore Tampa Bay where the most detections occurred in fall, coinciding with large red drum Sciaenops ocellatus spawning aggregations. We discuss the future of collaborative telemetry research, including current limitations and potential solutions to maximize its impact for understanding movement ecology, conducting ecosystem monitoring, and supporting fisheries management.

Marine Ecology Progress Series↗
USGS2021

A combined microbial and ecosystem metric of carbon retention efficiency explains land cover-dependent soil microbial biodiversity–ecosystem function relationships

While soil organic carbon (C) is the foundation of productive and healthy ecosystems, the impact of the ecology of microorganisms on C-cycling remains unknown. We manipulated the diversity, applied here as species richness, of the microbial community present in similar soils on two contrasting land-covers—an adjacent pasture and forest—and observed the transformations of plant detritus and soil organic matter (SOM) using stable isotope ( 13 C) tracing coupled with a novel nuclear magnetic resonance (NMR) experiment. The amount of detritus-C degraded was not affected by the microbial diversity (p > 0.05), however the fate of detritus- and SOM-C across the diversity gradient was complex and land cover-dependent. For example, in the pasture soil, higher diversity led to lower CO 2 production (p = 0.001), a trend driven solely by SOM-C mineralization. There was no relationship between diversity and detritus-C mineralization or production of new mineral-associations after one year (p > 0.05). In contrast, in the forest soil higher diversity resulted in increased detritus-C (p = 0.01) and SOM-C (p = 0.0008) mineralization and decreased mineral-associated organic matter formation (p = 0.02). In both land cover types, retention efficiency—a measure that integrates both microbial physiology and the ability of the ecosystem to retain C—explained C loss and transformation trends. Overall, this demonstrates that the trajectory of C gained and lost is altered by land management-induced changes to microbial communities, soil structure, and chemical characteristics underlying SOM persistence.

Biogeochemistry Letters↗
USGS2005

South San Francisco Bay tidal marsh vegetation and elevation surveys-Corkscrew Marsh, Bird Island, and Palo Alto Baylands, California, 1983

Changes in the topography and ecology of the San Francisco Bay Estuary ('Estuary') during the past 200 years have resulted in the loss of nearly 80 percent of the historical salt marsh in the region. Currently, numerous projects are being undertaken by federal, state, and local governments in an attempt to restore wetland habitat and ecosystem function at a number of locations within the Estuary. Much information is needed concerning the historical topographic and ecologic characteristics of the Estuary to facilitate these restoration efforts. This report presents previously unpublished vegetation and elevation data collected in 1983 by the California State Lands Commission at Corkscrew marsh, Bird Island, and Palo Alto Baylands, all located in South San Francisco Bay. These precise and detailed elevation and plant surveys represent a snapshot of South Bay flora before invasion by the Atlantic smooth cordgrass, Spartina alterniflora. Such precise elevation data are rare for relatively undisturbed marshes in the San Francisco Bay; publication of these historical data may facilitate wetland restoration efforts. Marsh-surface and tidal-channel elevations were determined at a total of 962 stations by differential leveling to established tidal benchmark stations at each site and referenced to Mean Lower Low Water (MLLW) relative to the National Tidal Datum Epoch (1960-78). In addition, presence or absence of nine salt marsh species, percentage plant cover, and percentage bare soil were recorded for 1-square meter quadrats at 648 stations where elevations were determined. Collectively, over the three sites, salt marsh vegetation ranged in elevation from 0.98 to 2.94 m above MLLW. S. foliosa and Salicornia virginica were the most frequently observed plant species. Atriplex patula, Deschampsia cespitosa, and Limonium californicum were each recorded at only one of the three sites.

Data Series↗
USGS2018

Food‐web structure and ecosystem function in the Laurentian Great Lakes—Toward a conceptual model

The relationship between food‐web structure (i.e., trophic connections, including diet, trophic position, and habitat use, and the strength of these connections) and ecosystem functions (i.e., biological, geochemical, and physical processes in an ecosystem, including decomposition, production, nutrient cycling, and nutrient and energy flows among community members) determines how an ecosystem responds to perturbations, and thus is key to understanding the adaptive capacity of a system (i.e., ability to respond to perturbation without loss of essential functions). Given nearly ubiquitous changing environmental conditions and anthropogenic impacts on global lake ecosystems, understanding the adaptive capacity of food webs supporting important resources, such as commercial, recreational, and subsistence fisheries, is vital to ecological and economic stability. Herein, we describe a conceptual framework that can be used to explore food‐web structure and associated ecosystem functions in large lakes. We define three previously recognised broad habitat compartments that constitute large lake food webs (nearshore, pelagic, and profundal). We then consider, at three levels, how energy and nutrients flow: (a) into each basal resource compartment; (b) within each compartment; and (c) among multiple compartments (coupling). Flexible shifts in food‐web structures (e.g., via consumers altering their diet or habitat) that sustain these flows in the face of perturbations provide evidence for adaptive capacity. We demonstrate the conceptual framework through a synthesis of food‐web structure and ecosystem function in the Laurentian Great Lakes, with emphasis on the upper trophic levels (i.e., fishes). Our synthesis showed evidence of notable adaptive capacity. For example, fishes increased benthic coupling in response to invasion by mussels and round gobies. However, we also found evidence of loss of adaptive capacity through species extirpations (e.g., widespread collapse in the abundance and diversity of ciscoes, Coregonus spp., except in Lake Superior). In large freshwater lakes, fishery managers have traditionally taken a top‐down approach, focusing on stocking and harvest policy. By contrast, water quality managers have focused on nutrient effects on chemical composition and lower trophic levels of the ecosystem. The synthesised conceptual model provides resource managers a tool to more systematically interpret how lower food‐web dynamics influence harvestable fish populations, and vice versa, and to act accordingly such that sustainable resource practices can be achieved. We identify key gaps in knowledge that impede a fuller understanding of the adaptive capacities of large lakes. In general, we found a greater uncertainty in our understanding of processes influencing energy and nutrient flow within and among habitats than flows into the system.

Great Lakes↗
USGS2020

An integrative ecological drought framework to span plant stress to ecosystem transformation

Droughts have increased globally in the twenty-first century and are expected to become more extreme and widespread in the future. Assessments of how drought affects plants and ecosystems lack consistency in scope and methodology, confounding efforts to mechanistically interpret structural and functional impacts and predict future transformations under climate change. To promote integration among studies, we identify water deficit conditions that are ecologically meaningful, clarify the stages in which ecological drought progresses, and consider approaches to synthesize drought effects across multiple species and ecosystems. This improved ecological drought framework reveals advantages of using different ecological drought metrics and strengthens approaches to distinguish ecosystem stress from crossing an irreversible threshold. We employ several well-studied examples from water-limited ecosystems, which contain plants that are often at their physiological limits and highly responsive to climate variability. We suggest that emerging research on early warning signs, drought recovery, and the effects of land management interventions be incorporated into the ecological drought framework. An integrative approach to understand ecological drought can accelerate scientific advancement and create opportunity to adapt and prepare for crossing irreversible ecosystem thresholds.

Ecosystems↗
USGS2008

Application of the new keystone-species concept to prairie dogs: How well does it work?

It has been suggested that the keystone-species concept should be dropped from ecology and conservation, primarily because the concept is poorly defined. This prompted Power et al. (1996) to refine the definition: keystone species have large effects on community structure or ecosystem function (i.e., high overall importance), and this effect should be large relative to abundance (i.e., high community importance). Using prairie dogs ( Cynomys spp.) as an example, I review operational and conceptual difficulties encountered in applying this definition. As applied to prairie dogs, the implicit assumption that overall importance is a linear function of abundance is invalid. In addition, community importance is sensitive to abundance levels, the definition of community, and sampling scale. These problems arise largely from the equation for community importance, as used in conjunction with removal experiments at single abundance levels. I suggest that we shift from the current emphasis on the dualism between keystone and nonkeystone species and instead examine how overall and community importance vary (1) with abundance, (2) across spatial and temporal scales, and (3) under diverse ecological conditions. In addition, I propose that a third criterion be incorporated into the definition: keystone species perform roles not performed by other species or processes. Examination of how these factors vary among populations of keystone species should help identify the factors contributing to, or limiting, keystone-level functions, thereby increasing the usefulness of the keystone-species concept in ecology and conservation. Although the quantitative framework of Power et al. falls short of being fully operational, my conceptual guidelines may improve the usefulness of the keystone-species concept. Careful attention to the factors that limit keystone function will help avoid misplaced emphasis on keystone species at the expense of other species.

Conservation Biology↗
USGS2003

Historic range of variability in landscape structure in subalpine forests of the Greater Yellowstone Area, USA

A measure of the historic range of variability (HRV) in landscape structure is essential for evaluating current landscape patterns of Rocky Mountain coniferous forests that have been subjected to intensive timber harvest. We used a geographic information system (GIS) and FRAGSTATS to calculate key landscape metrics on two ???130,000-ha landscapes in the Greater Yellowstone Area, USA: one in Yellowstone National Park (YNP), which has been primarily shaped by natural fires, and a second in the adjacent Targhee National Forest (TNF), which has undergone intensive clearcutting for nearly 30 years. Digital maps of the current and historical landscape in YNP were developed from earlier stand age maps developed by Romme and Despain. Maps of the TNF landscape were adapted from United States Forest Service Resource Information System (RIS) data. Key landscape metrics were calculated at 20-yr intervals for YNP for the period from 1705-1995. These metrics were used to first evaluate the relative effects of small vs. large fire events on landscape structure and were then compared to similar metrics calculated for both pre- and post-harvest landscapes of the TNF. Large fires, such as those that burned in 1988, produced a structurally different landscape than did previous, smaller fires (1705-1985). The total number of patches of all types was higher after 1988 (694 vs. 340-404 before 1988), and mean patch size was reduced by almost half (186 ha vs. 319-379 ha). The amount of unburned forest was less following the 1988 fires (63% vs. 72-90% prior to 1988), yet the number of unburned patches increased by nearly an order of magnitude (230 vs. a maximum of 41 prior to 1988). Total core area and mean core area per patch decreased after 1988 relative to smaller fires (???73,700 ha vs. 87,000-110,000 ha, and 320 ha vs. 2,123 ha, respectively). Notably, only edge density was similar (17 m ha-1 after 1988) to earlier landscapes (9.8-14.2 m ha-1). Three decades of timber harvesting dramatically altered landscape structure in the TNF. Total number of patches increased threefold (1,481 after harvest vs. 437 before harvest), and mean patch size decreased by ???70% (91.3 ha vs. 309 ha). None of the post-harvest landscape metrics calculated for the TNF fell within the HRV as defined in YNP, even when the post-1988 landscape was considered. In contrast, pre-harvest TNF landscape metrics were all within, or very nearly within, the HRV for YNP While reference conditions such as those identified by this study are useful for local and regional landscape evaluation and planning, additional research is necessary to understand the consequences of changes in landscape structure for population, community, ecosystem, and landscape function.

Landscape Ecology↗
USGS2011

Defining conservation priorities for freshwater fishes according to taxonomic, functional, and phylogenetic diversity

To date, the predominant use of systematic conservation planning has been to evaluate and conserve areas of high terrestrial biodiversity. Although studies in freshwater ecosystems have received recent attention, research has rarely considered the potential trade-offs between protecting different dimensions of biodiversity and the ecological processes that maintain diversity. We provide the first systematic prioritization for freshwaters (focusing on the highly threatened and globally distinct fish fauna of the Lower Colorado River Basin, USA) simultaneously considering scenarios of: taxonomic, functional, and phylogenetic diversity; contemporary threats to biodiversity (including interactions with nonnative species); and future climate change and human population growth. There was 75% congruence between areas of highest conservation priority for different aspects of biodiversity, suggesting that conservation efforts can concurrently achieve strong complementarity among all types of diversity. However, sizable fractions of the landscape were incongruent across conservation priorities for different diversity scenarios, underscoring the importance of considering multiple dimensions of biodiversity and highlighting catchments that contribute disproportionately to taxonomic, functional, and phylogenetic diversity in the region. Regions of projected human population growth were not concordant with conservation priorities; however, higher human population abundance will likely have indirect effects on native biodiversity by increasing demand for water. This will come in direct conflict with projected reductions in precipitation and warmer temperatures, which have substantial overlap with regions of high contemporary diversity. Native and endemic fishes in arid ecosystems are critically endangered by both current and future threats, but our results highlight the use of systematic conservation planning for the optimal allocation of limited resources that incorporates multiple and complementary conservation values describing taxonomic, functional, and phylogenetic diversity.

Ecological Applications↗
USGS2014

Impacts of drought and crayfish invasion on stream ecosystem structure and function

Drought and seasonal drying can be important disturbance events in many small streams, leading to intermittent or isolated habitats. Many small streams contain crayfish populations that are often keystone or dominant species in these systems. I conducted an experiment in stream mesocosms to examine the effects of drought and potential ecological redundancy of a native and invasive crayfish species. I examined the effects of drought (drought or control) and crayfish presence (none, native crayfish Orconectes eupunctus or invasive crayfish Orconectes neglectus ) on stream mesocosm structure and function (leaf breakdown, community metabolism, periphyton, sediment and chironomid densities) in a fully factorial design. Each mesocosm contained a deep and shallow section, and drought treatments had surface water present (5-cm depth) in deep sections where tiles and leaf packs were placed. Drought and crayfish presence did not interact for any response variable. Drought significantly reduced leaf breakdown, and crayfish presence significantly increased leaf breakdown. However, the native and invasive crayfish species did not differ significantly in their effects on leaf breakdown. Drought significantly reduced primary production and community respiration overall, whereas crayfish presence did not significantly affect primary production and community respiration. Neither drought nor crayfish presence significantly affected periphyton overall. However, drought significantly reduced autotrophic index (AI), and crayfish presence increased AI. Inorganic sediment and chironomid density were not affected by drought, but both were significantly reduced by crayfish presence. O. eupunctus reduced AI and sediment more than O. neglectus did. Neither drought nor crayfish species significantly affected crayfish growth or survival. Drought can have strong effects on ecosystem function, but weaker effects on benthic structure. Crayfish can have strong effects on ecosystem structure and function regardless of drought. In stream mesocosms, native and invasive crayfish species appeared largely ecologically redundant, although subtle differences in crayfish effects could cascade throughout the food web, and further research is needed to address this question.

River Research and Applications↗
USGS2013

Phenology-based, remote sensing of post-burn disturbance windows in rangelands

Wildland fire activity has increased in many parts of the world in recent decades. Ecological disturbance by fire can accelerate ecosystem degradation processes such as erosion due to combustion of vegetation that otherwise provides protective cover to the soil surface. This study employed a novel ecological indicator based on remote sensing of vegetation greenness dynamics (phenology) to estimate variability in the window of time between fire and the reemergence of green vegetation. The indicator was applied as a proxy for short-term, post-fire disturbance windows in rangelands; where a disturbance window is defined as the time required for an ecological or geomorphic process that is altered to return to pre-disturbance levels. We examined variability in the indicator determined for time series of MODIS and AVHRR NDVI remote sensing data for a database of ∼100 historical wildland fires, with associated post-fire reseeding treatments, that burned 1990–2003 in cold desert shrub steppe of the Great Basin and Columbia Plateau of the western USA. The indicator-based estimates of disturbance window length were examined relative to the day of the year that fires burned and seeding treatments to consider effects of contemporary variability in fire regime and management activities in this environment. A key finding was that contemporary changes of increased length of the annual fire season could have indirect effects on ecosystem degradation, as early season fires appeared to result in longer time that soils remained relatively bare of the protective cover of vegetation after fires. Also important was that reemergence of vegetation did not occur more quickly after fire in sites treated with post-fire seeding, which is a strategy commonly employed to accelerate post-fire vegetation recovery and stabilize soil. Future work with the indicator could examine other ecological factors that are dynamic in space and time following disturbance – such as nutrient cycling, carbon storage, microbial community composition, or soil hydrology – as a function of disturbance windows, possibly using simulation modeling and historical wildfire information.

California;Idaho;Nevada;Oregon;Utah;Washington↗
USGS2003

Predicting coastal retreat in the Florida Big Bend region of the Gulf Coast under climate change induced sea-level rise

Many wildlife preserves and refuges in coastal areas of our nation are slowly being inundated by rising sea-level. Land elevation and tidal flooding are key factors controlling the extent and zonation of coastal habitats. Warming of our global environment threatens to speed the rate of sea-level rise and perhaps further amplify the detrimental effects of tropical storms, droughts, and lightning fires. A field and modeling study was conducted to determine the current status of emergent vegetation and surficial hydrology and to predict marsh transgression under rising sea-level. Field surveys were conducted to relate vegetation cover and ecotones to surface elevation and tidal inundation. A regional site application of a GIS-based simulation model, WETLANDS, was developed to predict ecosystem response to changing sea-level conditions on a coastal reach of the Big Bend region in northwest Florida. The WETLANDS model contains functional probabilities of community tolerance to flooding conditions that dictate the rate and process of ecological succession and coastal retreat. Map information of hypsography and bathymetry of the study area were digitized and interpolated to construct a digital elevation model. Classified thematic mapper imagery of aquatic and terrestrial habitat at a community level was used to initialize model simulation by vegetative type. Model simulations were generated to predict a likelihood index of habitat change and conversion under different scenarios of sea-level rise. The WETLANDS model was applied to track the process and pattern of coastal inundation over space and time for low, mid, and high sea-level rise projections of 15, 50, and 95 cm over the next century. Model results indicated that major portions of this coastal zone will be permanently inundated by 2100, bringing about a combined migration of marsh habitat and displacement of forest habitat. Results show that lowland pine forests will undergo retreat on the order of thousands of hectares over the 21st century. Coastal marsh extent may actually increase slightly as a function of the low lying topography. Socioeconomic implications may be nominal for this area given its remote and fairly undeveloped and protected coast-202 line. The model offers a technological tool for research and policy purposes that allows for effective land and water management, risk assessment, and cumulative impact analysis of wetland systems and landscapes.

Florida↗
USGS2013

Winter climate change and coastal wetland foundation species: Salt marshes vs. mangrove forests in the southeastern United States

We live in an era of unprecedented ecological change in which ecologists and natural resource managers are increasingly challenged to anticipate and prepare for the ecological effects of future global change. In this study, we investigated the potential effect of winter climate change upon salt marsh and mangrove forest foundation species in the southeastern United States. Our research addresses the following three questions: (1) What is the relationship between winter climate and the presence and abundance of mangrove forests relative to salt marshes; (2) How vulnerable are salt marshes to winter climate change-induced mangrove forest range expansion; and (3) What is the potential future distribution and relative abundance of mangrove forests under alternative winter climate change scenarios? We developed simple winter climate-based models to predict mangrove forest distribution and relative abundance using observed winter temperature data (1970–2000) and mangrove forest and salt marsh habitat data. Our results identify winter climate thresholds for salt marsh–mangrove forest interactions and highlight coastal areas in the southeastern United States (e.g., Texas, Louisiana, and parts of Florida) where relatively small changes in the intensity and frequency of extreme winter events could cause relatively dramatic landscape-scale ecosystem structural and functional change in the form of poleward mangrove forest migration and salt marsh displacement. The ecological implications of these marsh-to-mangrove forest conversions are poorly understood, but would likely include changes for associated fish and wildlife populations and for the supply of some ecosystem goods and services.

Global Change Biology↗
USGS2003

Preface: Phragmites australis: A sheep in wolf's clothing?

A. problem with national priorities for control or prevention of aquatic nuisance species is that we often do not know the full extent of the problem, if there is one. To address this issue, we hosted a technical forum and workshop-Phragmites australis: A Sheep in Wolf's Clothing?--with a focus on new research and critical reviews that address the role of Phragmites as a noxious weed. ... The Workshop helped focus the national effort in new multidisciplinary research to better understand the ecology of P australis and its ecosystem-level effects on the structure and function of coastal wetlands.

Estuaries↗
USGS2017

Temporary wetlands: Challenges and solutions to conserving a ‘disappearing’ ecosystem

Frequent drying of ponded water, and support of unique, highly specialized assemblages of often rare species, characterize temporary wetlands, such as vernal pools, gilgais, and prairie potholes. As small aquatic features embedded in a terrestrial landscape, temporary wetlands enhance biodiversity and provide aesthetic, biogeochemical, and hydrologic functions. Challenges to conserving temporary wetlands include the need to: (1) integrate freshwater and terrestrial biodiversity priorities; (2) conserve entire ‘pondscapes’ defined by connections to other aquatic and terrestrial systems; (3) maintain natural heterogeneity in environmental gradients across and within wetlands, especially gradients in hydroperiod; (4) address economic impact on landowners and developers; (5) act without complete inventories of these wetlands; and (6) work within limited or non-existent regulatory protections. Because temporary wetlands function as integral landscape components, not singly as isolated entities, their cumulative loss is ecologically detrimental yet not currently part of the conservation calculus. We highlight approaches that use strategies for conserving temporary wetlands in increasingly human-dominated landscapes that integrate top-down management and bottom-up collaborative approaches. Diverse conservation activities (including education, inventory, protection, sustainable management, and restoration) that reduce landowner and manager costs while achieving desired ecological objectives will have the greatest probability of success in meeting conservation goals.

Biological Conservation↗
USGS2021

Establishment of baseline cytology metrics in nestling American kestrels (Falco sparverius): Immunomodulatory effects of the flame retardant isopropylated triarylphosphate isomers

Avian populations must mount effective immune responses upon exposure to environmental stressors such as avian influenza and xenobiotics. Although multiple immune assays have been tested and applied to various avian species, antibody-mediated immune responses in non-model avian species are not commonly reported due to the lack of commercially available species-specific antibodies. The objectives of the present study were to advance methods for studying wild bird immune responses and to apply these to the evaluation of cytological responses after exposure of American kestrels, Falco sparverius, to a commercial flame retardant mixture containing isopropylated triarylphosphate isomers (ITP). Hatchlings were gavaged daily with safflower oil or 1.5 ug/g bw/day of ITP suspended in safflower oil, then bled on days 9, 17, and 21. The ITP treatment group ( n = 18) and a subset of controls (Poly I:C treatment group; n = 10) were injected on days 9 and 15 with a synthetic analog of viral double-stranded RNA, polyinosinic:polycytidylic acid (Poly I:C), a toll-like receptor ligand and synthetic viral mimic, and responses compared to a sham injected control group (n = 8). The hypotheses tested whether kestrels showed immunological differences among treatment groups, genetic sex, and/or white blood cell (WBC) subpopulation type over time. A flow cytometry (FCM) gating strategy categorized heterophils (H), lymphocytes (L), and monocytes (M) and their proportions, and measured relative fluorescence in response to anti-chicken CD4 binding. Fluorescent cell surfaces and some granular/vacuolar inclusions were visualized by epifluorescence microscopy. A fourth subpopulation with higher levels of granularity than M but less than H became increasingly apparent with time and was gated along with the H subpopulation; its frequency of occurrence was lowest in the ITP group ( P = 0.0023). The percentages of cells differed among treatment groups, days, and sexes ( P = 0.0001). For both sexes, percentages of H and L were higher than M in control and Poly I:C. In the ITP group, L percentages were higher than H and M ( P = 0.0457), and H and L were higher than M on days 9 and 21 ( P = 0.0001). The ratios of H:L and H:WBC, indicators of robust immunity, were also higher on days 9 and 21 than on 17 ( P = 0.0079). For each sex, the highest levels of activity measured by FCM geometric means (GEO) of fluorescence (indicative of antibody binding) were observed on day 9 ( P = 0.0001 female, and P = 0.0011 male) in H over both L and M ( P < 0.0001 for each). In males, GEO of the Poly I:C group was higher than that of the ITP group ( P = 0.0374), with no difference observed among females over all days. By using a FCM algorithm for population comparisons of fluorescence to investigate binding within H, the T(x) scores indicated higher fluorescence in control and Poly I:C groups over ITP ( P = 0.0001). Unlike chickens, Gallus gallus , which express CD4 primarily on L, kestrels bound the commercial antibody primarily within the gated H subpopulation, suggesting an immunophenotypic difference between taxa, despite a ~60% identity of Falco CD4 amino acid sequences with chicken CD4. The emergent cell subset within the gated H presented dendritic-like cell (DLC) morphological and functional properties, apparently serving as an effector cell. This study adds interpretive context to ecological investigations of infection and of potential immunomodulation by emerging compounds, whereby the early innate responses are mediated by the various cell subsets serving as useful quantitative markers of immunological condition. Data showed that dietary exposure to ITP was immunosuppressive for male and female kestrels over the course of the experiment, reducing DLC frequency compared to the Poly I:C controls. Heterophils and DLC were important in facilitating innate immunological responses.

Environment International↗
USGS2020

A critical review on the potential impacts of neonicotinoid insecticide use: Current knowledge of environmental fate, toxicity, and implications for human health

Neonicotinoid insecticides are widely used in both urban and agricultural settings around the world. Historically, neonicotinoid insecticides have been viewed as ideal replacements for more toxic compounds, like organophosphates, due in part to their perceived limited potential to affect the environment and human health. This critical review investigates the environmental fate and toxicity of neonicotinoids and their metabolites and the potential risks associated with exposure. Neonicotinoids are found to be ubiquitous in the environment, drinking water, and food, with low-level exposure commonly documented below acceptable daily intake standards. Available toxicological data from animal studies indicate possible genotoxicity, cytotoxicity, impaired immune function, and reduced growth and reproductive success at low concentrations, while limited data from ecological or cross-sectional epidemiological studies have identified acute and chronic health effects ranging from acute respiratory, cardiovascular, and neurological symptoms to oxidative genetic damage and birth defects. Due to the heavy use of neonicotinoids and potential for cumulative chronic exposure, these insecticides represent novel risks and necessitate further study to fully understand their risks to humans.

Environmental Science: Processes and Impacts↗
USGS2019

Traversing the wasteland: A framework for assessing ecological threats to drylands

Drylands cover 41% of the Earth's terrestrial surface, play a critical role in global ecosystem function, and are home to over two billion people. Like other biomes, drylands face increasing pressure from global change, but many of these ecosystems are close to tipping points, which, if crossed, can lead to abrupt transitions and persistent degraded states. Their limited but variable precipitation, low soil fertility, and low productivity have given rise to a perception that drylands are wastelands, needing societal intervention to bring value to them. Negative perceptions of drylands synergistically combine with conflicting sociocultural values regarding what constitutes a threat to these ecosystems. In the present article, we propose a framework for assessing threats to dryland ecosystems and suggest we must also combat the negative perceptions of drylands in order to preserve the ecosystem services that they offer.

Arizona, Colorado, New Mexico, Utah↗