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At least 1,621 records · Page 90Linked to original sources
USGS2020

Assessing the risks posed by SARS-CoV-2 in and via North American bats — Decision framing and rapid risk assessment

The novel β-coronavirus, SARS-CoV-2, may pose a threat to North American bat populations if bats are exposed to the virus through interaction with humans, if the virus can subsequently infect bats and be transmitted among them, and if the virus causes morbidity or mortality in bats. Further, if SARS-CoV-2 became established in bat populations, it could possibly serve as a source for new infection in humans, domesticated animals, or other wild animals. Wildlife management agencies in the United States are concerned about these potential risks and have begun to issue guidance regarding work that brings humans into contact with bats, but decision making is difficult because of the high degree of uncertainty about many of the relevant processes that could lead to virus transmission and establishment. The risk assessment described in this report was undertaken to provide management agencies with an understanding of the likelihood that the various steps in the causal pathways would lead to SARS-CoV-2 infection of North American bats from people. This assessment focused on the active season for bats in the temperate zone of North America (April 15 through November 15), and used Myotis lucifugus (little brown bats) as a surrogate species. At the time of this work (April 2020), no empirical data about the effects of SARS-CoV-2 on North American bats were available, so a formal process of expert judgment was used to elicit estimates of the underlying parameters. Twelve experts in bat ecology, epidemiology, virology, and wildlife disease from the United States, United Kingdom, and Australia participated in the elicitation. A Monte Carlo simulation model was used to integrate the parameter estimates elicited from the experts and to predict the likelihood of exposure and infection in bats through a series of transmission pathways, with particular attention to capturing uncertainty in the predictions. Given the current state of knowledge as expressed by the expert panel, the results of this assessment indicate that there is a non-negligible risk of transmission of SARS-CoV-2 from humans to bats. For example, if a research scientist were shedding SARS-CoV-2 virus while handling bats under the field protocols used in North America prior to the COVID-19 pandemic, the risk model indicates that 50 percent (uncertainty, 15–84 percent) of those bats could be exposed to virus, and 17 percent (uncertainty, 3–51 percent) could become infected. Use of personal protective equipment, especially a respirator, is expected to reduce the exposure risk. The expert panel estimated that exposure risk from research scientists could be reduced 94–96 percent (uncertainty, 86–99 percent) through proper use of appropriate N95 respirators (a type of mechanical filter worn over the nose and mouth), dedicated clothing (such as Tyvek coveralls), and gloves. Should any North American bats become infected with SARS-CoV-2, the expert panel estimated that there is an approximately 33-percent chance the virus could spread within a bat population. This study, conducted by the U.S. Geological Survey in cooperation with the U.S. Fish and Wildlife Service, identified several critical uncertainties that could affect the estimate of risks associated with SARS-CoV-2 entering bat populations—notably, the underlying probability that a human would be shedding virus while working with bats, the likelihood of the virus replicating in bat tissue, and the likelihood of transmission of the virus within bat populations. Ongoing empirical work during May–October 2020 may shed light on these issues. Follow-up work is needed to better understand the probability of transmission of SARS-CoV-2 to bats from the general public; the manner in which the probabilities of exposure, infection, and transmission would differ during hibernation compared to the breeding season; and the likelihood of important effects, like morbidity and mortality in bats, the possibility of zoonosis from a North American bat reservoir, and effects of and on other wildlife.

North America↗
USGS1997

Bioavailability of biologically sequestered cadmium and the implications of metal detoxification

The deposit-feeding oligochaete Limnodrilus hoffmeisteri possesses metallothionein-like proteins and metal-rich granules for storing and detoxifying cadmium (Cd). In this study we investigated the bioavailability of Cd sequestered within this oligochaete by conducting feeding experiments with 109Cd-labeled oligochaetes and the omnivorous grass shrimp Palaemonetes pugio. We also make predictions on Cd trophic transfer based on oligochaete subcellular Cd distributions and absorption efficiencies of Cd by shrimp Cytosol [including metallothionein-like proteins and other proteins) and a debris fraction (including metal-rich granules and tissue fragments) isolated from homogenized 109Cd-labeled oligochaetes were embedded in gelatin and fed to shrimp. The 109Cd absorption efficiencies of shrimp fed these subcellular fractions were 84.8 and 48.6%, respectively, and were significantly different (p < 0.001), indicating that 109Cd bound in these fractions was not equally available to a predator. Mass balance equations demonstrate that shrimp fed whole worms absorb 61.5% of the ingested 109Cd, an absorption efficiency similar to that obtained experimentally (57.1%). Furthermore, the majority of the absorbed 109Cd comes from the fraction containing metallothionein-like proteins (i.e. cytosol). 109Cd absorbed from the debris fraction probably comes from the digestion of tissue fragments, rather than metal-rich granules. The ecological significance of these findings is that prey detoxification mechanisms may mediate the bioreduction or bioaccumulation of toxic metals along fond chains by altering metal bioavailability. Another important finding is that trophic transfer of metal can be predicted based on the subcellular metal distribution of prey.

Marine Ecology Progress Series↗
USGS2020

Fostering real-time climate adaptation: Analyzing past, current, and forecast temperature to understand the dynamic risk to Hawaiian honeycreepers from avian malaria

Various vector control options are increasingly being considered to safeguard forest birds in their natural habitats from avian malaria transmission. However, vector control options require localized deployment that is not logistically, ethically, ecologically, nor economically viable everywhere and all the time. Based on thermal tolerances of the sporogonic stages of avian malaria (Plasmodium relictum) parasite and its vector, the southern house mosquito (Culex quinquefasciatus), we examined the long-term weather trends for three high value, forest bird refuges (Alakai Wilderness Preserve on Kaua’i, Hanawi Natural Area Reserve on Maui, and Hakalau Forest National Wildlife Refuge on Hawai’i Island) to understand the temporal and site-specific differences of temperature-driven suitability for localized avian malaria transmission. On average, Alakai had mean ambient temperatures suitable for both the vector’s immature stage development and parasite sporogonic development most of the time (85.3%), indicating that observed variability in vector abundance or disease transmission may be driven by other factors. At higher elevation sites like Hakalau and Hanawi, current mean ambient temperatures suitable only for vector development prevail (91.7% and 96.6%, respectively), while mean ambient temperatures for both vector and parasite sporogonic development seldom occur (4.4% and 0% respectively). Our results not only show differences in the temperature suitability for transmission across elevation, but also different levels of vulnerability to avian malaria transmission with any additional projected increase in temperature. For instance, under a conservative warming scenario of 1.0 °C, the joint temperature suitability of parasite and vector development increases at higher elevation sites such as Hakalau (+35.8%) and Hanawi (+15.4%). While mean ambient temperatures suitable for both vector and parasite development already occur most of the time at Alakai, the occurrence also increases (+8.4%) as well under this conservative warming scenario. By linking current site-specific weather data to real-time weather forecasts, we developed a real-time avian malaria warning system to assist managers in identifying conditions when vector control is most needed at these three selected study sites. This online tool determines when conditions are likely to be suitable for local development of P. relictum and C. quinquefasciatus at Alakai, Hanawi, and Hakalau. This tool illustrates how managers can incorporate climate and current weather patterns into decision making without having to consider the uncertainties of long-term climatic and ecological projections.

Hawaii↗
USGS2022

Balancing model generality and specificity in management-focused habitat selection models for Gunnison sage-grouse

Identifying, protecting, and restoring habitats for declining wildlife populations is foundational to conservation and recovery planning for any species at risk of decline. Resource selection analysis is a key tool to assess habitat and prescribe management actions. Yet, it can be challenging to map suitable resource conditions across a wide range of ecological contexts and use the resulting models to identify effective and universal habitat improvement actions. We developed a management-centric modeling approach that sought to balance the need to evaluate the consistency of key habitat conditions and improvement actions across multiple, distinct populations, while allowing context-specific environmental variables and spatial scales to nuance selection responses that form the basis of location-specific management prescriptions. To demonstrate this approach, we developed a set of habitat selection models for Gunnison sage-grouse ( Centrocercus minimus ), a threatened species under the U.S. Endangered Species Act. Conservation, species recovery, and habitat management efforts are needed in six isolated satellite populations (San Miguel, Crawford, Piñon Mesa, Dove Creek, Cerro Summit-Cimarron-Sims, and Poncha Pass) where environmental conditions differ, and the already small number of birds are declining. We used multi-scale and seasonal resource selection analyses to quantify relationships between environmental conditions and sites used by animals. All models included key habitat variables often altered through management actions to assess their differential influences across models. We found important similarities and differences among satellites, indicating that, although some rules of thumb are generally well-grounded, the consideration of population-specific environmental differences could increase the efficiency of local habitat improvement actions. Sage-grouse also had diverse responses to resource conditions at different scales, indicating that regional spatial (e.g., landscape) and local patch scale can differentially influence expected habitat improvements associated with where such management actions are implemented. Although context variables such as topography cannot be manipulated, sage-grouse associations revealed information that could guide the siting of improvement actions. This approach to balancing management objectives associated with habitat assessment may benefit spatially-structured populations with different environmental contexts and species with complex habitat needs and associations.

Colorado↗
USGS2004

Wildfire-resistant biological soil crusts and fire-induced loss of soil stability in Palouse prairies, USA

Frequent low-intensity fires are a natural component of the ecology of the Palouse prairies of northwestern North America. To study the effects of fire upon biological soil crusts (BSCs) occurring in these grasslands, we sampled three burned (in 2000) sites and three unburned sites in the Hell's Canyon area (OR, USA) ???1 year post-fire. We measured vascular plant and BSC cover, soil microbe pigmentation, texture and chemistry, and soil surface physical properties (stability and rugosity). Festuca idahoensis was two times more abundant in unburned plots (P=0.0006), and vascular plant and litter cover were generally higher in unburned plots. At the community scale, there was no difference in the lichen and moss species composition, suggesting much less drastic effects of fire on BSCs than reported in other systems. Soil surface stability (measured using slake value) was significantly lower in burned sites than unburned sites (median value=5 versus 6, P=0.008), a result which is likely due to the greater density of lichens and mosses encountered in the unburned plots. Soil microbe pigmentation was lower in burned plots (P=0.03), suggesting that the biomass of photosynthetic microbes had decreased; however, the presence of intra- and extracellular pigments in burned soils indicates that microorganisms were not eradicated. Pigments most strongly associated with cyanobacteria were more abundant in unburned sites, suggesting that cyanobacteria may have been more strongly impacted by the fire than other BSC components. Composition of nutrients and surface rugosity did not differ significantly between treatments. We hypothesize that Palouse prairie soil crusts are relatively resistant to wildfire because of low fire intensity and their occupation of space away from the vascular plant fuel load.

Applied Soil Ecology↗
USGS2023

Using eDNA metabarcoding to establish targets for freshwater fish composition following river restoration

Establishing realistic targets for fish community composition is needed to assess the effectiveness of river restoration projects. We used environmental DNA (eDNA) metabarcoding with MiFish primers to obtain estimates of fish community composition across 17 sites upstream, downstream and within a restoration mitigation project area (Kaihotsu–Kasumi) located in the Shigenobu River system, Ehime Prefecture, Japan. We evaluate the benefits of using eDNA to quickly, sensitively, and extensively gather data to establish existing fish community composition in the restoration area, as well as potential future short-term, medium-term, and long-term targets of species assemblages that could realistically emerge following dispersal into the project area from upstream and downstream populations. We compare results from eDNA metabarcoding with species lists obtained from contemporaneous capture surveys and historical information. Nonmetric multidimensional scaling plots of community composition obtained from eDNA surveys showed that the Kaihotsu–Kasumi restoration area and surrounding river reaches were divided into three clusters: upper reaches, middle and lower reaches, and estuarine reaches. The Kaihotsu–Kasumi restoration area sites were included in the group containing the middle and lower reaches of the inflow and outflow rivers that were near the restoration area. We detected a total of twenty-six species in this group, twenty-one native species and five non-native species. Therefore, these native species were considered suitable as short-term target species with high potential for dispersal into Kaihotsu–Kasumi restoration area. By comparison, only 14 species would have been selected as target species based on capture surveys and historical literature. One factor increasing the resolution of our eDNA surveys was our ability to identify the presence of intraspecific lineages of Misgurnus anguillicaudatus (Clades A and B), which were missed by the capture surveys. These results indicate that the eDNA metabarcoding method can provide more comprehensive and realistic short-term target species estimates than capture surveys, as well as provide higher resolution monitoring through intraspecific lineage detection.

Global Ecology and Conservation↗
USGS2014

Fine scale habitat use by age-1 stocked muskellunge and wild northern pike in an upper St. Lawrence River bay

Radio telemetry of stocked muskellunge ( n = 6) and wild northern pike ( n = 6) was used to track late summer and fall movements from a common release point in a known shared nursery bay to test the hypothesis that age-1 northern pike and stocked muskellunge segregate and have different habitat affinities. Water depth, temperature, substrate and aquatic vegetation variables were estimated for each muskellunge ( n = 103) and northern pike ( n = 131) position and nested ANOVA comparisons by species indicated differences in habitat use. Muskellunge exhibited a greater displacement from the release point and used habitat in shallower water depths (mean = 0.85 m, SE = 0.10) than northern pike (mean = 1.45 m, SE = 0.08). Both principal components analysis (PCA) and principal components ordination (PCO) were used to interpret underlying gradients relative to fish positions in two-dimensional space. Our analysis indicated that a separation of age-1 northern pike and muskellunge occurred 7 d post-release. This first principal component explained 48% of the variation in habitat use. Northern pike locations were associated with deeper habitats that generally had softer silt substrates and dense submersed vegetation. Muskellunge locations post-acclimation showed greater association with shallower habitats containing firmer sandy and clay substrates and emergent vegetation. The observed differences in habitat use suggest that fine-scale ecological separation occurred between these stocked muskellunge and wild northern pike, but small sample sizes and potential for individual variation limit extension of these conclusions. Further research is needed to determine if these patterns exist between larger samples of fishes over a greater range of habitats.

Journal of Great Lakes Research↗
USGS2013

Hybrid seine for full fish community collections

Seines are simple and effective fish collection gears, but the net mesh size influences how well the catch represents the fish communities. We designed and tested a hybrid seine with a dual-mesh bag (1/4″ and 1/8″) and compared the fish assemblage collected by each mesh. The fine-mesh net retained three times as many fish and collected more species (as many as eight), including representatives of several rare species, than did the coarser mesh. The dual-mesh bag permitted us to compare both sizes and species retained by each layer and to develop species-specific abundance correction factors, which allowed comparison of catches with the coarse-mesh seine used for earlier collections. The results indicate that a hybrid seine with coarse-mesh wings and a fine-mesh bag would enhance future studies of fish communities, especially when small-bodied fishes or early life stages are the research focus.

Journal of Freshwater Ecology↗
USGS2013

Spatio-temporal dynamics of pneumonia in bighorn sheep

Bighorn sheep mortality related to pneumonia is a primary factor limiting population recovery across western North America, but management has been constrained by an incomplete understanding of the disease. We analysed patterns of pneumonia-caused mortality over 14 years in 16 interconnected bighorn sheep populations to gain insights into underlying disease processes. 2. We observed four age-structured classes of annual pneumonia mortality patterns: all-age, lamb-only, secondary all-age and adult-only. Although there was considerable variability within classes, overall they differed in persistence within and impact on populations. Years with pneumonia-induced mortality occurring simultaneously across age classes (i.e. all-age) appeared to be a consequence of pathogen invasion into a naïve population and resulted in immediate population declines. Subsequently, low recruitment due to frequent high mortality outbreaks in lambs, probably due to association with chronically infected ewes, posed a significant obstacle to population recovery. Secondary all-age events occurred in previously exposed populations when outbreaks in lambs were followed by lower rates of pneumonia-induced mortality in adults. Infrequent pneumonia events restricted to adults were usually of short duration with low mortality. 3. Acute pneumonia-induced mortality in adults was concentrated in fall and early winter around the breeding season when rams are more mobile and the sexes commingle. In contrast, mortality restricted to lambs peaked in summer when ewes and lambs were concentrated in nursery groups. 4. We detected weak synchrony in adult pneumonia between adjacent populations, but found no evidence for landscape-scale extrinsic variables as drivers of disease. 5. We demonstrate that there was a >60% probability of a disease event each year following pneumonia invasion into bighorn sheep populations. Healthy years also occurred periodically, and understanding the factors driving these apparent fade-out events may be the key to managing this disease. Our data and modelling indicate that pneumonia can have greater impacts on bighorn sheep populations than previously reported, and we present hypotheses about processes involved for testing in future investigations and management.

Journal of Animal Ecology↗
USGS2022

A Resist-Accept-Direct decision-support tool for walleye Sander vitreus (Mitchill) management in Wisconsin

Large-scale modelling and prediction provide insight into general influences of climate change on inland recreational fisheries; however, small-scale dynamics and local expertise will be key in developing explicit goals for managing recreational fisheries as the climate changes. The resist-accept-direct (RAD) framework encompasses the entire decision space managers consider when addressing climate influences in their local system, but to decide whether to resist, accept or direct, managers need tools to understand how specific waterbodies will be influenced by climate change. Here, a decision-support tool was developed and applied to the walleye recreational fishery in Wisconsin, USA as an example of how to link the RAD framework to real-world management of a large recreational fishery. The tool and broadscale results described here, indicating a widespread shift away from resist strategies by mid-century, can be used by managers to inform decisions about whether to resist, accept, or direct for specific walleye populations.

Wisconsin↗
USGS2015

Habitat fragmentation in coastal southern California disrupts genetic connectivity in the cactus wren ( Campylorhynchus brunneicapillus )

Achieving long-term persistence of species in urbanized landscapes requires characterizing population genetic structure to understand and manage the effects of anthropogenic disturbance on connectivity. Urbanization over the past century in coastal southern California has caused both precipitous loss of coastal sage scrub habitat and declines in populations of the cactus wren ( Campylorhynchus brunneicapillus ). Using 22 microsatellite loci, we found that remnant cactus wren aggregations in coastal southern California comprised 20 populations based on strict exact tests for population differentiation, and 12 genetic clusters with hierarchical Bayesian clustering analyses. Genetic structure patterns largely mirrored underlying habitat availability, with cluster and population boundaries coinciding with fragmentation caused primarily by urbanization. Using a habitat model we developed, we detected stronger associations between habitat-based distances and genetic distances than Euclidean geographic distance. Within populations, we detected a positive association between available local habitat and allelic richness and a negative association with relatedness. Isolation-by-distance patterns varied over the study area, which we attribute to temporal differences in anthropogenic landscape development. We also found that genetic bottleneck signals were associated with wildfire frequency. These results indicate that habitat fragmentation and alterations have reduced genetic connectivity and diversity of cactus wren populations in coastal southern California. Management efforts focused on improving connectivity among remaining populations may help to ensure population persistence.

California↗
USGS2016

Genetic and phenotypic variation along an ecological gradient in lake trout Salvelinus namaycush

Background Adaptive radiation involving a colonizing phenotype that rapidly evolves into at least one other ecological variant, or ecotype, has been observed in a variety of freshwater fishes in post-glacial environments. However, few studies consider how phenotypic traits vary with regard to neutral genetic partitioning along ecological gradients. Here, we present the first detailed investigation of lake trout Salvelinus namaycush that considers variation as a cline rather than discriminatory among ecotypes. Genetic and phenotypic traits organized along common ecological gradients of water depth and geographic distance provide important insights into diversification processes in a lake with high levels of human disturbance from over-fishing. Results Four putative lake trout ecotypes could not be distinguished using population genetic methods, despite morphological differences. Neutral genetic partitioning in lake trout was stronger along a gradient of water depth, than by locality or ecotype. Contemporary genetic migration patterns were consistent with isolation-by-depth. Historical gene flow patterns indicated colonization from shallow to deep water. Comparison of phenotypic ( Pst ) and neutral genetic variation ( Fst ) revealed that morphological traits related to swimming performance (e.g., buoyancy, pelvic fin length) departed more strongly from neutral expectations along a depth gradient than craniofacial feeding traits. Elevated phenotypic variance with increasing water depth in pelvic fin length indicated possible ongoing character release and diversification. Finally, differences in early growth rate and asymptotic fish length across depth strata may be associated with limiting factors attributable to cold deep-water environments. Conclusion We provide evidence of reductions in gene flow and divergent natural selection associated with water depth in Lake Superior. Such information is relevant for documenting intraspecific biodiversity in the largest freshwater lake in the world for a species that recently lost considerable genetic diversity and is now in recovery. Unknown is whether observed patterns are a result of an early stage of incipient speciation, gene flow-selection equilibrium, or reverse speciation causing formerly divergent ecotypes to collapse into a single gene pool.

Lake Superior, Isle Royale↗
USGS2013

Significance of headwater streams and perennial springs in ecological monitoring in Shenandoah National Park

Shenandoah National Park has been monitoring water chemistry and benthic macroinvertebrates in stream ecosystems since 1979. These monitoring efforts were designed to assess the status and trends in stream condition associated with atmospheric deposition (acid rain) and changes in forest health due to gypsy moth infestations. The primary objective of the present research was to determine whether the current long-term macroinvertebrate and water-quality monitoring program in Shenandoah National Park was failing to capture important information on the status and trends in stream condition by not sufficiently representing smaller, headwater streams. The current benthic-macroinvertebrate and water-chemistry sampling designs do not include routine collection of data from streams with contributing watershed areas smaller than 100 hectares, even though these small streams represent the overwhelming proportion of total stream length in the park. In this study, we sampled headwater sites, including headwater stream reaches (contributing watershed area approximately 100 hectares (ha) and perennial springs, in the park for aquatic macroinvertebrates and water chemistry and compared the results with current and historical data collected at long-term ecological monitoring (LTEM) sites on larger streams routinely sampled as part of ongoing monitoring efforts. The larger purpose of the study was to inform ongoing efforts by park managers to evaluate the effectiveness and efficiency of the current aquatic monitoring program in light of other potential stressors (for example, climate change) and limited resources. Our results revealed several important findings that could influence management decisions regarding long-term monitoring of park streams. First, we found that biological indicators of stream condition at headwater sites and perennial springs generally were more indicative of lower habitat quality and were more spatially variable than those observed at sites on routinely monitored larger streams. We hypothesized that poorer stream condition observed in smaller streams was due to stream drying that occurs more frequently in headwater areas. We also found that biological and water-chemistry measures responded differently to landscape drivers. Variation in most biological endpoints was driven primarily by stream size and was only secondarily associated with bedrock geology. In contrast, water chemistry showed essentially the opposite pattern, with underlying geology explaining much of the variation and stream size being of secondary importance. Therefore, expanding the LTEM program to include headwater areas would yield substantially different biological information, whereas broad inferences regarding spatial patterns in water chemistry would probably not change. Although significant differences in community composition were observed among streams of different sizes, no taxa were unique to headwater sites. All taxa collected at the 45 headwater sites also had been collected at one or more LTEM sites during one or more years. This observation indicates that headwater sites in the park may be structured by biotic nestedness; consequently, focusing management efforts on preserving the species pool at the larger LTEM sites would likely result in the protection of most taxa parkwide. Finally, linkages (correlations) between water chemistry and biological measures of stream condition were signficantly stronger when assessed at the LTEM sites than when assessed at the springs or headwater sites, indicating that conditions at downstream sites may be better indicators of water-quality trends.

Virginia↗
USGS2013

Niche overlap, threshold food densities, and limits to prey depletion for a diving duck assemblage in an estuarine bay

Planning for marine conservation often requires estimates of the amount of habitat needed to support assemblages of interacting species. During winter in subtidal San Pablo Bay, California, the 3 main diving duck species are lesser scaup Aythya affinis (LESC), greater scaup A. marila (GRSC), and surf scoter Melanitta perspicillata (SUSC), which all feed almost entirely on the bivalve Corbula amurensis . Decreased body mass and fat, increased foraging effort, and major departures of these birds appeared to result from food limitation. Broad overlap in prey size, water depth, and location suggested that the 3 species responded similarly to availability of the same prey. However, an energetics model that accounts for differing body size, locomotor mode, and dive behavior indicated that each species will become limited at different stages of prey depletion in the order SUSC, then GRSC, then LESC. Depending on year, 35 to 66% of the energy in Corbula standing stocks was below estimated threshold densities for profitable foraging. Ectothermic predators, especially flounders and sturgeons, could reduce excess carrying capacity for different duck species by 4 to 10%. A substantial quantity of prey above profitability thresholds was not exploited before most ducks left San Pablo Bay. Such pre-depletion departure has been attributed in other taxa to foraging aggression. However, in these diving ducks that showed no overt aggression, this pattern may result from high costs of locating all adequate prey patches, resulting reliance on existing flocks to find food, and propensity to stay near dense flocks to avoid avian predation. For interacting species assemblages, modeling profitability thresholds can indicate the species most vulnerable to food declines. However, estimates of total habitat needed require better understanding of factors affecting the amount of prey above thresholds that is not depleted before the predators move elsewhere.

Marine Ecology Progress Series↗
USGS2024

Lingering impacts of the 2014-2016 northeast Pacific marine heatwave on seabird demography in Cook Inlet, Alaska (USA)

A protracted period (2014-2016) of anomalously warm water in the northeast Pacific Ocean precipitated an extensive die-off of common murres Uria aalge (hereafter ‘murres’) during 2015-2016, accompanied by reduced colony attendance and reproductive success of murres and black-legged kittiwakes Rissa tridactyla (‘kittiwakes’) starting in 2015. Most murres died of starvation following a large-scale reduction in abundance and quality of forage fish. To assess murre and kittiwake recovery following the marine heatwave, we monitored their demographics at 2 colonies (Chisik and Gull Islands) in Cook Inlet, Alaska (USA), from 2016 to 2019. Compared to historic data (1995-1999), we observed declines and increased variability in colony attendance and productivity across species and colonies, and predation was widespread. At Chisik, where food limitations were common during historic studies, both species experienced substantial population declines and reproductive failures in all 4 years (2016-2019) following the heatwave. At Gull, a typically productive colony during historic studies, murres failed to fledge chicks for 3 years (2016-2018) following the heatwave. By 2019, murre productivity recovered to about half that observed during historic studies (0.28 vs. 0.54 chicks per pair), but populations had declined by half. Kittiwake population size at Gull declined a quarter from historic counts, and reproduction alternated between complete breeding failures (2016/2018) and high productivity (2017/2019). These multi-year demographic impacts indicate lingering effects of the heatwave on kittiwakes and murres through forage fish depletion and increased predator disturbance, and possibly other stressors. It remains unknown whether populations can rebound to historic levels. If so, recovery would likely take decades.

Alaska↗
USGS2019

Trade-offs relating to grassland and forest mine reclamation approaches in the central Appalachian region and its implications for the songbird community

Surface mining in the Appalachian region, USA, converts large areas of mature forest to early-successional habitat. This shift in landscape structure has the potential to reduce habitat availability and suitability for forest-dwelling songbirds by reducing and fragmenting mature forest, but also to increase habitat availability for grassland and shrubland-associated songbirds. We examined the influence of mountaintop mining/valley fill (MTMVF) reclamation habitats (grassland, shrubland, and remnant forest) on songbird community composition and abundance at three former MTMVF mines in southwestern West Virginia, relative to intact forest. We quantified the songbird community in 1999 and 2000 using point counts arranged throughout the mine complexes to assess landscape composition of the songbird community. Community analysis showed songbirds had strong associations with their respective guild based on species’ habitat preferences. Although remnant and intact forest treatments had similar species compositions, the forest interior guild had greater richness in intact than remnant forest. Total species richness was greatest in the reclaimed shrubland treatment. Focal species analysis followed similar trends as community assessments, as species’ abundances within treatment types were strongly associated with species’ habitat preferences. Our study indicates reclamation habitat decisions (i.e. grasslands versus forests) can have large effects on avian community composition. Determining appropriate mine restoration actions depends on the suite of species desired for long-term occupancy and their conservation priority.

Appalachian Basin↗
USGS2000

Spatial variation in fish assemblages across a beaver-influenced successional landscape

Beavers are increasingly viewed as “ecological engineers,” having broad effects on physical, chemical, and biological attributes of north-temperate landscapes. We examine the influence of both local successional processes associated with beaver activity and regional geomorphic boundaries on spatial variation in fish assemblages along the Kabetogama Peninsula in Voyageurs National Park, northern Minnesota, USA. Fish abundance and species richness exhibited considerable variation among drainages along the peninsula. Geological barriers to fish dispersal at outlets of some drainages has reduced fish abundance and species richness. Fish abundance and species richness also varied within drainages among local environments associated with beaver pond succession. Fish abundance was higher in upland ponds than in lowland ponds, collapsed ponds, or streams, whereas species richness was highest in collapsed ponds and streams. Cluster analyses based on fish abundance at sites classified according to successional environment indicated that four species (northern redbelly dace, Phoxinus eos ; brook stickleback, Culaea inconstans ; finescale dace, P. neogaeus ; and fathead minnow, Pimephales promelas ), were predominant in all successional environments. Several less abundant species were added in collapsed ponds and streams, with smaller size classes of large lake species (e.g., black crappie, Pomoxis nigromaculatus ; smallmouth bass, Micropertus dolomieui ; yellow perch, Perca flavescens ; and burbot, Lota lota ) being a component of these less abundant species. The addition of smaller size classes of large lake species indicates that dispersal of early life-history stages from Kabetogama Lake played a role in determining the species richness and composition of less abundant species in successional environments on the peninsula. Furthermore, collapsed-pond and stream environments closer to Kabetogama Lake had higher species richness than similar successional sites located farther from the lake. Cluster analyses based on fish abundance at sites classified according to drainage indicated that species composition among drainages was influenced both by the presence or absence of geological barriers to fish dispersal and the nonrandom distribution of collapsed ponds and streams. Based on these results, we present a hierarchical conceptual model suggesting how geomorphic boundaries and beaver pond succession interact to influence fish assemblage attributes. The presence of a productive and diverse fish assemblage in headwater streams of north-temperate areas requires the entire spatial and temporal mosaic of successional habitats associated with beaver activity, including those due to the creation and abandonment of beaver ponds. The ultimate impact of the local successional mosaic on fishes, however, will be strongly influenced by the regional geomorphic context in which the mosaic occurs.

Ecology↗
USGS2021

Exposure to domoic acid is an ecological driver of cardiac disease in southern sea otters

Harmful algal blooms produce toxins that bioaccumulate in the food web and adversely affect humans, animals, and entire marine ecosystems. Blooms of the diatom Pseudo-nitzschia can produce domoic acid (DA), a toxin that most commonly causes neurological disease in endothermic animals, with cardiovascular effects that were first recognized in southern sea otters. Over the last 20 years, DA toxicosis has caused significant morbidity and mortality in marine mammals and seabirds along the west coast of the USA. Identifying DA exposure has been limited to toxin detection in biological fluids using biochemical assays, yet measurement of systemic toxin levels is an unreliable indicator of exposure dose or timing. Furthermore, there is little information regarding repeated DA exposure in marine wildlife. Here, the association between long-term environmental DA exposure and fatal cardiac disease was investigated in a longitudinal study of 186 free-ranging sea otters in California from 2001 – 2017, highlighting the chronic health effects of a marine toxin. A novel Bayesian spatiotemporal approach was used to characterize environmental DA exposure by combining several DA surveillance datasets and integrating this with life history data from radio-tagged otters in a time-dependent survival model. In this study, a sea otter with high DA exposure had a 1.7-fold increased hazard of fatal cardiomyopathy compared to an otter with low exposure. Otters that consumed a high proportion of crab and clam had a 2.5- and 1.2-times greater hazard of death due to cardiomyopathy than otters that consumed low proportions. Increasing age is a well-established predictor of cardiac disease, but this study is the first to identify that DA exposure affects the risk of cardiomyopathy more substantially in prime-age adults than aged adults. A 4-year-old otter with high DA exposure had 2.3 times greater risk of fatal cardiomyopathy than an otter with low exposure, while a 10-year old otter with high DA exposure had just 1.2 times greater risk. High Toxoplasma gondii titers also increased the hazard of death due to heart disease 2.4-fold. Domoic acid exposure was most detrimental for prime-age adults, whose survival and reproduction are vital for population growth, suggesting that persistent DA exposure will likely impact long-term viability of this threatened species. These results offer insight into the pervasiveness of DA in the food web and raise awareness of under-recognized chronic health effects of DA for wildlife at a time when toxic blooms are on the rise.

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