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USGS2008

Bats prove to be rich reservoirs for emerging viruses

Emerging pathogens, many of them viruses, continue to surprise us, providing many newly recognized diseases to study and to try to control. Many of these emergent viruses are zoonotic, transmitted from reservoirs in wild or domestic animals to humans, either by insect vectors or by exposure to the droppings or tissues of such animals. One rich- but, until recently, underappreciated-source of emergent viruses is bats ( Chiroptera , meaning "hand wing"). Accounting for 1,116, or nearly one fourth, of the 4,600 recognized species of mammals, bats are grouped into two suborders Megachiroptera, which contains a single family, Pteropodidae, consisting of 42 genera and 186 species, and Microchiroptera, which contains 17 families, 160 genera, and 930 species. Although bats are among the most abundant, diverse, and geographically dispersed orders of terrestrial mammals, research on these flying mammals historically focused more on their habits and outward characteristics than on their role in carrying microorganisms and transmitting pathogens to other species. Even in those cases where bats were known to carry particular pathogens, the microbiologists who studied those pathogens typically knew little about the bat hosts. Hence, investigators now are seeking to explain how variations of anatomy, physiology, ecology, and behavior influence the roles of bats as hosts for viral pathogens.

Microbe↗

USGS2025

Spatiotemporal synchrony of climate and fire occurrence across North American forests (1750-1880)

Aim Increasing aridity has driven widespread synchronous fire occurrence in recent decades across North America. The lack of historical (pre-1880) fire records limits our ability to understand long-term continental fire-climate dynamics. The goal of this study is to use tree-ring reconstructions to determine the relationships between spatiotemporal patterns in historical climate and widespread fire occurrence in North American forests, and whether they are stable through time. This information will address a major knowledge gap required to inform projections of future fire. Location North American Forests. Time Period 1750–1880 CE. Major Taxa Studies Trees. Methods We applied regionalisation methods to tree-ring reconstructions of historical summer soil moisture and annual fire occurrence to independently identify broad- and fine-scale climate and fire regions based on common inter-annual variability. We then tested whether the regions were stable through time and for spatial correspondence between the climate and fire regions. Last, we used correlation analysis to quantify the strength of the fire-climate associations through time. Results We found that broad-scale historical patterns in climate and fire have strong spatial coherence. Although climate and fire regions vary over time, large core areas of the regions were stable. The association between climate and fire varied through time and was strongest in western North America, likely due to a combination of factors, such as the magnitude of drought frequency and severity, as well as varying use of fire by human communities. Main Conclusions The historical perspective gained through tree-ring reconstructions of climate and fire patterns and their association suggests that climate-driven synchrony of fire across large areas of the continent in recent decades is not unprecedented, will likely continue into the future, and may exhibit similar spatial patterns.

North America↗

USGS2022

Golden eagle occupancy surveys and monitoring strategy in coastal southern California, United States

Golden eagles ( Aquila chrysaetos ) are of increasing conservation concern in western North America. Effective conservation measures for this wide-ranging, federally protected raptor species require monitoring frameworks that accommodate strong inference on the status of breeding populations across vast landscapes. We used a broad-scale sampling design to identify relationships between landscape conditions, detection rates, and site occupancy by territorial pairs of golden eagles in coastal southern California, United States. In 2016 and 2017, we surveyed 175 territory-sized sample sites (13.9-km 2 randomly selected grid cells) up to four times each year and detected a pair of eagles at least once in 22 (12.6%) sites. The probability of detecting pairs of eagles varied substantially between years and declined with increasing amounts of forest cover at survey sites, which obscured observations of eagles during ground-based surveys. After accounting for variable detection, the mean estimate of expected site occupancy by eagle pairs was 0.156 (SE = 0.081). Site-level estimates of occupancy were greatest (>0.30) at sample sites with more rugged terrain conditions, <20% human development, and lower amounts of scrubland vegetation cover. The proportion of a sample site with open grassland or forest cover was not strongly correlated with occupancy. We estimated that approximately 16% of the 5,338-km 2 sampling frame was used by resident pairs of golden eagles, corresponding to a sparsely distributed population of about 60 pairs (95% CI = 19 – 151 pairs). Our study provided baseline data for future surveys of golden eagles along with a widely applicable monitoring framework for identifying spatial conservation priorities in urbanizing landscapes.

California↗

USGS2022

Global review of the effects of small carnivores on threatened species

The absences of large carnivores from many ecosystems, human-induced landscape changes, and resource supplementation have been theorized to increase the abundance of small carnivore species around the world. Overabundant and/or unconstrained small carnivores can have significant effects on specific prey species that, in some cases, can cascade through entire ecosystems. Here, we review the effects of small carnivores on threatened species. We focus on four well-studied families (Procyonidae, Mephitidae, Mustelidae, and Herpestidae) and emphasize that this is a global conservation issue with consequences for biodiversity. We review and compare the impacts that small carnivores can have on a variety of prey taxa including small mammals, nesting avian and reptilian species, and rare invertebrates. We differentiate between native and exotic small carnivores because this is often an important distinction in terms of the impact severity and range of effects. In addition to direct lethal effects (i.e. predation), small carnivores can also impact threatened species as disease vectors and through competition or overexploitation, which can disrupt communities via ecological release or extinction. Furthermore, we explore other case studies in which small carnivores have had positive effects on threatened species and discuss studies that reveal other taxa responsible for exerting stronger negative effects on threatened prey. We offer some concluding remarks about global small carnivore conservation and emphasize the need for decision-analytic approaches and robust analyses that can improve our assessment of how populations of threatened species can be affected. To date, indirect effects are especially difficult to measure in the field and many studies have provided only anecdotal or correlative results, signalling a need for improving our scientific methodologies and management approaches.

Book chapter↗

USGS2022

Towards critical white ice conditions in lakes under global warming

The quality of lake ice is of uppermost importance for ice safety and under-ice ecology, but its temporal and spatial variability is largely unknown. Here we conducted a coordinated lake ice quality sampling campaign across the Northern Hemisphere during one of the warmest winters since 1880 and show that lake ice during 2020/2021 commonly consisted of unstable white ice, at times contributing up to 100% to the total ice thickness. We observed that white ice increased over the winter season, becoming thickest and constituting the largest proportion of the ice layer towards the end of the ice cover season when fatal winter drownings occur most often and light limits the growth and reproduction of primary producers. We attribute the dominance of white ice before ice-off to air temperatures varying around the freezing point, a condition which occurs more frequently during warmer winters. Thus, under continued global warming, the prevalence of white ice is likely to substantially increase during the critical period before ice-off, for which we adjusted commonly used equations for human ice safety and light transmittance through ice.

Nature Communications↗

USGS2014

Spatial genetic structure of bristle-thighed curlews (Numenius tahitiensis): Breeding area differentiation not reflected on the non-breeding grounds

Migratory birds occupy geographically and ecologically disparate areas during their annual cycle with conditions on breeding and non-breeding grounds playing separate and important roles in population dynamics. We used data from nuclear microsatellite and mitochondrial DNA control region loci to assess the breeding and non-breeding spatial genetic structure of a transoceanic migrant shorebird, the bristle-thighed curlew. We found spatial variance in the distribution of allelic and haplotypic frequencies between the curlew's two breeding areas in Alaska but did not observe this spatial structure throughout its non-breeding range on low-lying tropical and subtropical islands in the Central Pacific (Oceania). This suggests that the two breeding populations do not spatially segregate during the non-breeding season. Lack of migratory connectivity is likely attributable to the species' behavior, as bristle-thighed curlews exhibit differential timing of migration and some individuals move among islands during non-breeding months. Given the detrimental impact of many past and current human activities on island ecosystems, admixture of breeding populations in Oceania may render the bristle-thighed curlew less vulnerable to perturbations there, as neither breeding population will be disproportionally affected by local habitat losses or by stochastic events. Furthermore, lack of migratory connectivity may enable bristle-thighed curlews to respond to changing island ecosystems by altering their non-breeding distribution. However, availability of suitable non-breeding habitat for curlews in Oceania is increasingly limited on both low-lying and high islands by habitat loss, sea level rise, and invasive mammalian predators that pose a threat to flightless and flight-compromised curlews during the molting period.

Conservation Genetics↗

USGS2005

Human land use influences chronic wasting disease prevalence in mule deer

Human alteration of landscapes can affect the distribution, abundance, and behavior of wildlife. We explored the effects of human land use on the prevalence of chronic wasting disease (CWD) in mule deer (Odocoileus hemionus) populations residing in north-central Colorado. We chose best approximating models estimating CWD prevalence in relation to differences in human land use, sex, and geographic location. Prevalence was higher in developed areas and among male deer, suggesting anthropogenic influences on the occurrence of disease. We also found a relatively high degree of variation in prevalence across the three study sites, suggesting that spatial patterns in disease may be influenced by other factors operating at a broader, landscape scale. Our results suggest that multiple factors, including changes in land use, differences in exposure risk between sexes, and landscape-scaled heterogeneity, are associated with CWD prevalence in north-central Colorado.

Ecological Applications↗

USGS2016

Evaluating the adequacy of a reference site pool for ecological assessments in environmentally complex regions

Many advances in the field of bioassessment have focused on approaches for objectively selecting the pool of reference sites used to establish expectations for healthy waterbodies, but little emphasis has been placed on ways to evaluate the suitability of the reference-site pool for its intended applications (e.g., compliance assessment vs ambient monitoring). These evaluations are critical because an inadequately evaluated reference pool may bias assessments in some settings. We present an approach for evaluating the adequacy of a reference-site pool for supporting biotic-index development in environmentally heterogeneous and pervasively altered regions. We followed common approaches for selecting sites with low levels of anthropogenic stress to screen 1985 candidate stream reaches to create a pool of 590 reference sites for assessing the biological integrity of streams in California, USA. We assessed the resulting pool of reference sites against 2 performance criteria. First, we evaluated how well the reference-site pool represented the range of natural gradients present in the entire population of streams as estimated by sites sampled through probabilistic surveys. Second, we evaluated the degree to which we were successful in rejecting sites influenced by anthropogenic stress by comparing biological metric scores at reference sites with the most vs fewest potential sources of stress. Using this approach, we established a reference-site pool with low levels of human-associated stress and broad coverage of environmental heterogeneity. This approach should be widely applicable and customizable to particular regional or programmatic needs.

California↗

USGS2015

Global Cropland Area Database (GCAD) derived from Remote Sensing in Support of Food Security in the Twenty-first Century: Current Achievements and Future Possibilities

The precise estimation of the global agricultural cropland- extents, areas, geographic locations, crop types, cropping intensities, and their watering methods (irrigated or rainfed; type of irrigation) provides a critical scientific basis for the development of water and food security policies (Thenkabail et al., 2012, 2011, 2010). By year 2100, the global human population is expected to grow to 10.4 billion under median fertility variants or higher under constant or higher fertility variants (Table 1) with over three quarters living in developing countries, in regions that already lack the capacity to produce enough food. With current agricultural practices, the increased demand for food and nutrition would require in about 2 billion hectares of additional cropland, about twice the equivalent to the land area of the United States, and lead to significant increases in greenhouse gas productions (Tillman et al., 2011). For example, during 1960-2010 world population more than doubled from 3 billion to 7 billion. The nutritional demand of the population also grew swiftly during this period from an average of about 2000 calories per day per person in 1960 to nearly 3000 calories per day per person in 2010. The food demand of increased population along with increased nutritional demand during this period (1960-2010) was met by the “green revolution” which more than tripled the food production; even though croplands decreased from about 0.43 ha/capita to 0.26 ha/capita (FAO, 2009). The increase in food production during the green revolution was the result of factors such as: (a) expansion in irrigated areas which increased from 130 Mha in 1960s to 278.4 Mha in year 2000 (Siebert et al., 2006) or 399 Mha when you do not consider cropping intensity (Thenkabail et al., 2009a, 2009b, 2009c) or 467 Mha when you consider cropping intensity (Thenkabail et al., 2009a; Thenkabail et al., 2009c); (b) increase in yield and per capita food production (e.g., cereal production from 280 kg/person to 380 kg/person and meat from 22 kg/person to 34 kg/person (McIntyre, 2008); (c) new cultivar types (e.g., hybrid varieties of wheat and rice, biotechnology); and (d) modern agronomic and crop management practices (e.g., fertilizers, herbicide, pesticide applications). However, some of the factors that lead to the green revolution have stressed the environment to limits leading to salinization and decreasing water quality. For example, from 1960 to 2000, the phosphorous use doubled from 10 million tons to 20 MT, pesticide use tripled from near zero to 3 MT, and nitrogen use as fertilizer increased to a staggering 80 MT from just 10 MT (Foley et al., 2007; Khan and Hanjra, 2008). Further, diversion of croplands to bio-fuels is already taking water away from food production; the economics, carbon sequestration, environmental, and food security impacts of biofuel production are net negative (Lal and Pimentel, 2009), leaving us with a carbon debt (Gibbs et al., 2008; Searchinger et al., 2008). Climate models predict that in most regions of the world the hottest seasons on record will become the norm by the end of the century-an outcome that bodes ill for feeding the world (Kumar and Singh, 2005). Also, crop yield increases of the green revolution era have now stagnated (Hossain et al., 2005). Thereby, further increase in food production through increase in cropland areas and\or increased allocations of water for croplands are widely considered unsustainable and\or infeasible. Indeed, cropland areas have even begun to decrease in many 3 parts of the World due to factors such as urbanization, industrialization, and salinization. Furthermore, ecological and environmental imperatives such as biodiversity conservation and atmospheric carbon sequestration have put a cap on the possible expansion of cropland areas to other lands such as forests and rangelands. Other important factors limit food security. These include factors such as diversion of croplands to biofuels (Bindraban et al., 2009), limited water resources for irrigation expansion (Turral et al., 2009), limits on agricultural intensifications, loss of croplands to urbanization (Khan and Hanjra, 2008), increasing meat consumption (and associated demands on land and water) (Vinnari and Tapio, 2009), environmental infeasibility for cropland expansion (Gordon et al., 2009), and changing climate have all put pressure on our continued ability to sustain global food security in the twenty-first century. So, how does the World continue to meet its food and nutrition needs?. Solutions may come from bio-technology and precision farming, however developments in these fields are not currently moving at rates that will ensure global food security over next few decades. Further, there is a need for careful consideration of possible harmful effects of bio-technology. We should not be looking back 30– 50 years from now, like we have been looking back now at many mistakes made during the green revolution. During the green revolution the focus was only on getting more yield per unit area. Little thought was put about serious damage done to our natural environments, water resources, and human health as a result of detrimental factors such as uncontrolled use of herbicides-pesticides-nutrients, drastic groundwater mining, and salinization of fertile soils due to over irrigation. Currently, there is talk of a “second green revolution” or even an “ever green revolution”, but clear ideas on what these terms actually mean are still debated and are evolving. One of the biggest issues that are not given adequate focus is the use of large quantities of water for food production. Indeed, an overwhelming proportion (60-90%) of all human water use in India goes for producing their food (Falkenmark, M., & Rockström, 2006). But such intensive water use for food production is no longer tenable due to increasing pressure for water use alternatives such as increasing urbanization, industrialization, environmental flows, bio-fuels, and recreation. This has brought into sharp focus the need to grow more food per drop of water leading to a “blue revolution”

Book chapter↗

USGS2020

Post-fire vegetation response in a repeatedly burned low-elevation sagebrush steppe protected area provides insights about resilience and invasion resistance

Sagebrush steppe ecosystems are threatened by human land-use legacies, biological invasions, and altered fire and climate dynamics. Steppe protected areas are therefore of heightened conservation importance but are few and vulnerable to the same impacts broadly affecting sagebrush steppe. To address this problem, sagebrush steppe conservation science is increasingly emphasizing a focus on resilience to fire and resistance to non-native annual grass invasion as a decision framework. It is well-established that the positive feedback loop between fire and annual grass invasion is the driving process of most contemporary steppe degradation. We use a newly developed ordinal zero-augmented beta regression model fit to large-sample vegetation monitoring data from John Day Fossil Beds National Monument, USA, spanning 7 years to evaluate fire responses of two native perennial foundation bunchgrasses and two non-native invasive annual grasses in a repeatedly burned, historically grazed, and inherently low-resilient protected area. We structured our model hierarchically to support inferences about variation among ecological site types and over time after also accounting for growing-season water deficit, fine-scale topographic variation, and burn severity. We use a state-and-transition conceptual diagram and abundances of plants listed in ecological site reference conditions to formalize our hypothesis of fire-accelerated transition to ecologically novel annual grassland. Notably, big sagebrush ( Artemisia tridentata ) and other woody species were entirely removed by fire. The two perennial grasses, bluebunch wheatgrass ( Pseudoroegneria spicata ) and Thurber's needlegrass ( Achnatherum thurberianum ) exhibited fire resiliency, with no apparent trend after fire. The two annual grasses, cheatgrass ( Bromus tectorum ) and medusahead ( Taeniatherum caput-medusae ), increased in response to burn severity, most notably medusahead. Surprisingly, we found no variation in grass cover among ecological sites, suggesting fire-driven homogenization as shrubs were removed and annual grasses became dominant. We found contrasting responses among all four grass species along gradients of topography and water deficit, informative to protected-area conservation strategies. The fine-grained influence of topography was particularly important to variation in cover among species and provides a foothold for conservation in low-resilient, aridic steppe. Broadly, our study demonstrates how to operationalize resilience and resistance concepts for protected areas by integrating empirical data with conceptual and statistical models.

Oregon↗

USGS2012

Retrospective analysis of bottlenose dolphin foraging: a legacy of anthropogenic ecosystem disturbance

We used stable isotope analysis to investigate the foraging ecology of coastal bottlenose dolphins (Tursiops truncatus) in relation to a series of anthropogenic disturbances. We first demonstrated that stable isotopes are a faithful indicator of habitat use by comparing muscle isotope values to behavioral foraging data from the same individuals. δ 13 C values increased, while δ 34 S and δ 15 N values decreased with the percentage of feeding observations in seagrass habitat. We then utilized stable isotope values of muscle to assess temporal variation in foraging habitat from 1991 to 2010 and collagen from tooth crown tips to assess the time period 1944 to 2007. From 1991 to 2010, δ 13 C values of muscle decreased while δ 34 S values increased indicating reduced utilization of seagrass habitat. From 1944 to 1989 δ 13 C values of the crown tip declined significantly, likely due to a reduction in the coverage of seagrass habitat and δ 15 N values significantly increased, a trend we attribute to nutrient loading from a rapidly increasing human population. Our results demonstrate the utility of using marine mammal foraging habits to retrospectively assess the extent to which anthropogenic disturbance impacts coastal food webs.

Florida↗

USGS2019

Reducing wet ammonium deposition in Rocky Mountain National Park: The development and evaluation of a pilot early warning system for agricultural operations in eastern Colorado

Agricultural emissions are the primary source of ammonia (NH3) deposition in Rocky Mountain National Park (RMNP), a Class I area, that is granted special air quality protections under the Clean Air Act. Between 2014 and 2016, the pilot phase of the Colorado agricultural nitrogen early warning system (CANEWS) was developed for agricultural producers to voluntarily and temporarily minimize emissions of NH3 during periods of upslope winds. The CANEWS was created using trajectory analyses driven by outputs from an ensemble of numerical weather forecasts together with the climatological expertise of human forecasters. Here, we discuss the methods for the CANEWS and offer preliminary analyses of 33 months of the CANEWS based on atmospheric deposition data from two sites in RMNP as well as responses from agricultural producers after warnings were issued. Results showed that the CANEWS accurately predicted 6 of 9 high N deposition weeks at a lower-elevation observation site, but only 4 of 11 high N deposition weeks at a higher-elevation site. Sixty agricultural producers from 39 of Colorado’s agricultural operations volunteered for the CANEWS, and a two-way line of communication between agricultural producers and scientists was formed. For each warning issued, an average of 23 producers responded to a post-warning survey. Over 75% of responding CANEWS participants altered their practices after an alert. While the current effort was insufficient to reduce atmospheric deposition, we were encouraged by the collaborative spirit between agricultural, scientific, and resource management communities. Solving a broad and complex social-ecological problem requires both a technological approach, such as the CANEWS, and collaboration and trust from all participants, including agricultural producers, land managers, university researchers, and environmental agencies.

Colorado↗

USGS2007

Home ranges and habitat use of sloth bears Melursus ursinus inornatus in Wasgomuwa National Park, Sri Lanka

We studied home ranges and habitat selection of 10 adult sloth bears Melursus ursinus inornatus at Wasgomuwa National Park, Sri Lanka during 2002-2003. Very little is known about the ecology and behaviour of M. u. inornatus, which is a subspecies found in Sri Lanka. Our study was undertaken to assess space and habitat requirements typical of a viable population of M. u. inornatus to facilitate future conservation efforts. We captured and radio-collared 10 adult sloth bears and used the telemetry data to assess home-range size and habitat use. Mean 95% fixed kernel home ranges were 2.2 km2 (SE = 0.61) and 3.8 km2 (SE = 1.01) for adult females and males, respectively. Although areas outside the national park were accessible to bears, home ranges were almost exclusively situated within the national park boundaries. Within the home ranges, high forests were used more and abandoned agricultural fields (chenas) were used less than expected based on availability. Our estimates of home-range size are among the smallest reported for any species of bear. Thus, despite its relatively small size, Wasgomuwa National Park may support a sizeable population of sloth bears. The restriction of human activity within protected areas may be necessary for long-term viability of sloth bear populations in Sri Lanka as is maintenance of forest or scrub cover in areas with existing sloth bear populations and along potential travel corridors. ?? Wildlife Biology 2007.

Wildlife Biology↗

USGS2005

National Acid Precipitation Assessment Program Report to Congress: An integrated assessment

Acid deposition, more commonly known as acid rain, occurs when emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) react in the atmosphere (with water, oxygen, and oxidants) to form various acidic compounds. These acidic compounds then fall to earth in either a wet form (rain, snow, and fog) or a dry form (gases, aerosols, and particles). Prevailing winds transport the acidic compounds hundreds of miles, often across state and national borders. At certain levels the acidic compounds, including small particles such as sulfates and nitrates can cause many negative human health and environmental effects. While ecosystems are subject to many stresses, including land-use changes, climate change, and variations in hydrologic and meteorologic cycles, the scientific literature has clearly demonstrated that these pollutants can: • Degrade air quality, • Impair visibility, • Damage public health, • Acidify lakes and streams, • Harm sensitive forests, • Harm sensitive coastal ecosystems, and • Accelerate the decay of building materials, paints, and cultural artifacts such as buildings, statues, and sculptures. Title IV was passed by Congress as part of the 1990 Clean Air Act Amendments to reduce emissions of SO 2 and NO x from fossil fuel-burning power plants in order to protect ecosystems suffering damage from acid deposition and to improve air quality. At the same time, the National Acid Precipitation Assessment Program (NAPAP) was asked to periodically assess and report to Congress on the implementation of the Acid Rain Program, recent scientific knowledge surrounding acid deposition and its effects, and the reduction in acid deposition necessary to prevent adverse ecological effects. This NAPAP Report focuses primarily on emission reductions from power plants, both in terms of assessing past reductions under the Acid Rain Program and in projecting the ecological effects of additional reductions of SO 2 and NO x . It should be noted that power generation currently contributes approximately 69% of the SO 2 emissions and 22% of the NO x emissions nationwide. This contribution is decreasing as emissions from power generation continue to decrease, making the other sources of these pollutants more prominent. Modeling suggests that even if SO 2 emissions from power generation were reduced to zero, some lakes and streams would remain acidic due to acid deposition. However, there are several other regulations that reduce emissions of SO 2 and NO x from these non-power generation sources, such as the Tier II mobile source standards, the Heavy Duty Diesel standards, and the Clean Air Non-Road Diesel Rule, that have also been promulgated since 1990. These regulations, primarily designed to bring counties into attainment with fine particle and ozone air quality standards, also incidentally reduce emissions that contribute to acid deposition. Implementation of Title IV has successfully and substantially reduced emissions of SO 2 and NO x from power generation at a significantly lower cost than expected: • In 2002, SO 2 emissions were 10.2 million tons, 35% lower than 1990 emissions and 40% lower than 1980 emissions.* • In 2002, NO x emissions were 4.5 million tons, 33% lower than 1990 emissions. In addition, SO 2 emissions from all sources have decreased by 32% since 1990 and emissions of NO x from all sources have decreased by 12% since 1990. Power generating sources continue to close in on the goal of reducing power plant SO 2 emissions from 1980 levels by 50% (to 8.95 million tons) as required by the 1990 Clean Air Act. Power generating sources have also exceeded the goal of a two million ton reduction in NO x emissions from projected 2000 levels as required by the 1990 Clean Air Act. These emission reductions have contributed to measurable improvements in air quality, reductions in acid deposition, and the beginnings of recovery of acid-sensitive waters in some areas: • SO2 concentrations in the atmosphere (a precursor to fine particles and acid deposition) have decreased since 1990. Average annual SO2 concentrations in the Northeast in 2000–2002 were 40% lower than they were in 1989–1991, concentrations in the mid-Atlantic were 30% lower, concentrations in the Southeast were 35% lower, and concentrations in the Midwest were 45% lower. • Sulfate concentrations in the atmosphere (a major component of fine particles, especially in the East) have decreased since 1990 as well. Average annual sulfate concentrations in the Northeast and Midwest in 2000–2002 were approximately 30% lower than they were in 1989–1991, and concentrations in the mid-Atlantic and Southeast were 25% lower. • Wet sulfate deposition, a major component of acid rain, has also decreased since 1990. Average annual sulfate deposition in the Northeast in 2000–2002 was 40% lower than it was in 1989–1991, deposition in the mid-Atlantic and Midwest was 35% lower, and deposition in the Southeast was 25% lower. • Wet nitrate deposition has not decreased regionally from historical levels because of the relatively moderate NO x reduction from power plants and the continuing large contribution (over 50% of total NOx emissions) from other sources of NO x such as vehicles and nonroad vehicles. • Although visibility has begun to improve in some parts of the U.S., there is still significant impairment of visibility in many national parks and other Class I areas throughout the U.S. • Acid neutralizing capacity is beginning to rise in some surface waters in the Northeast, including lakes in the Adirondack Mountains (see graphic below). This is an indication that recovery from acidification is occurring in those areas.

Report to Congress↗

USGS2007

Mercury speciation in piscivorous fish from mining-impacted reservoirs

Guadalupe Reservoir (GUA), California, and Lahontan Reservoir (LAH), Nevada, U.S. are both affected either directly or indirectly by the legacy of gold and silver mining in the Sierra Nevada during the nineteenth century. Analysis of total mercury in fish from these lentic systems consistently indicate elevated concentrations (>1 μg·g-1 wet weight; hereinafter, all concentrations are reported as wet weight unless indicated otherwise) well above the U.S. Environmenal Protection Agency's human consumption advisory level for fish (<0.3 μg·g-1). Replicate X-ray absorption near edge structure (XANES) analyses on largemouth bass and hybrid striped bass from GUA and LAH were performed to determine predominant chemical species of mercury accumulated by these high-trophic-level piscivores that are exposed to elevated mercury through trophic transfer in mining-impacted lentic systems. Despite distinct differences in mercury source, the proximity of the source, and concentrations of complexing ligands, results of XANES analysis clearly indicated that mercury accumulated in these individual fish from the two reservoirs were dominated by methylmercury cysteine complexes. These findings are consistent with results from commercial fish species inhabiting marine environments which are presumed to include differing mercury sources (e.g., atmospheric, hydrothermal, or benthic). The dominance of methylmercury cysteine complexes in muscle tissues of fish obtained from such contrasting environments and exposure conditions suggests that a generic toxicological model for the consumption of fish could be applicable over a wide range of ecologic settings.

Environmental Science & Technology↗

USGS2019

Guidance for assessing interregional ecoystem service flows

Ecosystem services (ES) assessments commonly focus on a specific biophysical region or nation and take its geographic borders as the system boundary. Most geographical regions are, however, not closed systems but are open and telecoupled with other regions through ES imports and exports, which are mediated by fluxes of matter, energy and information. Interregional ES flows are often linked to national economies and may affect issues of national security and global equity. To date, however, methodologies for interregional ES flow assessments have been published in dispersed literature. This paper provides a three-step guidance for the assessment of four different types of interregional ES flows (traded goods, passive biophysical flows, species migration and dispersal and information flows), in order to complement national ecosystem assessments. The three steps are to (i) define the goal and scope of interregional ES flow assessments, (ii) quantify the interregional ES flows using a tiered approach and (iii) interpret results in terms of uncertainties, consequences and governance options. We compile different indicators for assessing interregional ES flows and evaluate their suitability for national ES assessments. Finally, in order to value the various outcomes of telecouplings, including their implications for human well-being, we relate the interregional ES flow indicators to the Sustainable Development Goals. We discuss how regional studies can assess a country‘s dependence and impact on "overseas" ES. This guidance towards systematic assessment of interregional ES flows provides a first step to measure and quantify externalised environmental costs and can contribute to the development of indicators to address interregional imbalances in trade, foreign policy and beyond.

Ecological Indicators↗

USGS2020

How and why is the timing and occurrence of seasonal migrants in the Gulf of Maine changing due to climate?

Plants and animals undergo certain recurring life-cycle events, such as migrations between summer and winter habitats or the annual blooming of plants. Known as phenology, the timing of these events is very sensitive to changes in climate (and changes in one species’ phenology can impact entire food webs and ecosystems). Shifts in phenology have been described as a “fingerprint” of the temporal and spatial responses of wildlife to climate change impacts. Thus, phenology provides one of the strongest indicators of the adaptive capacity of organisms (or the ability of organisms to cope with future environmental conditions). In this study, researchers are exploring how the timing and occurrence of a number of highly migratory marine animals is changing due to a series of climatic and ecological shifts. First, using existing long-term historical data series, they will determine the direction and magnitude of how migration, abundance, or other phenological factors have changed for marine mammals, sea turtles, and fishes that migrate into the Gulf of Maine on a seasonal basis. Because marine animals are inherently difficult to detect, the team will apply dynamic occupancy models to evaluate seasonal migration patterns and habitat use across multiple habitats in the Gulf of Maine region. The project team will also synthesize regional information on a key, ecologically-important prey fish, sandlance, whose timing and abundance is a strong predictor of the occurrence and behavior of predator species targeted in this study as well as a range of other regional fish and wildlife of conservation and management concern. Results from this component of the project will identify coastal fish and wildlife species that are relatively more or less able to adapt and thus potentially vulnerable to climate change; determine the likely primary drivers of those changes; and identify data gaps and future monitoring needs. Ultimately, this information will be available and useful for regional coastal management and adaptation decisions that will allow managers to effectively plan for the future. In a second component of the project, researchers will focus specifically on changes in migration patterns of the endangered North Atlantic right whale. While shifts in the distribution and time of recurring life events are adaptive responses that may help species cope with climate impacts, they can also lead to changes in how species interact with humans. The North Atlantic right whale is one of the most endangered whale species on the planet. In the North Atlantic Ocean, ship strikes and entanglements with commercial fishing gear represent fatal threats to right whales. Recent reports suggest that North Atlantic right whale migration patterns have changed. Many researchers posit that shifts in migration are responsible for recent increases in the overlap between right whales and human activities, especially fishing. To help understand how changes in right whale movements and behaviors may overlap with ship traffic, and thus put the animals at risk of encountering vessels, we will combine right whale habitat models with ship traffic maps. The end result will be a set of maps identifying risk levels.

Gulf of Maine↗

USGS2014

Non-native fishes in Florida freshwaters: a literature review and synthesis

Non-native fishes have been known from freshwater ecosystems of Florida since the 1950s, and dozens of species have established self-sustaining populations. Nonetheless, no synthesis of data collected on those species in Florida has been published until now. We searched the literature for peer-reviewed publications reporting original data for 42 species of non-native fishes in Florida that are currently established, were established in the past, or are sustained by human intervention. Since the 1950s, the number of non-native fish species increased steadily at a rate of roughly six new species per decade. Studies documented (in decreasing abundance): geographic location/range expansion, life- and natural-history characteristics (e.g., diet, habitat use), ecophysiology, community composition, population structure, behaviour, aquatic-plant management, and fisheries/aquaculture. Although there is a great deal of taxonomic uncertainty and confusion associated with many taxa, very few studies focused on clarifying taxonomic ambiguities of non-native fishes in the State. Most studies were descriptive; only 15 % were manipulative. Risk assessments, population-control studies and evaluations of effects of non-native fishes were rare topics for research, although they are highly valued by natural-resource managers. Though some authors equated lack of data with lack of effects, research is needed to confirm or deny conclusions. Much more is known regarding the effects of lionfish ( Pterois spp.) on native fauna, despite its much shorter establishment time. Natural-resource managers need biological and ecological information to make policy decisions regarding non-native fishes. Given the near-absence of empirical data on effects of Florida non-native fishes, and the lengthy time-frames usually needed to collect such information, we provide suggestions for data collection in a manner that may be useful in the evaluation and prediction of non-native fish effects.

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