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117 record(s) found.

Papers & Reports Corticosterone Mediates a Growth-Survival Tradeoff for an Amphibian Exposed to Increased Salinity
Authors: B J Tornabene; Blake R Hossack; E J Crespi; C W Breuner
Outlet: Journal of Experimental Zoology Part A
Life-history tradeoffs are common across taxa, but growth-survival tradeoffs—which usually enhance survival at a cost to growth—are less frequently investigated. Increased salinity (NaCl) is a prevalent anthropogenic disturbance that may cause a growth-survival tradeoff for amphibians. Although physiological mechanisms mediating tradeoffs are seldom investigated, hormones are prime candidates. Corticosterone (CORT) is a steroid hormone that independently influences survival and growth and may provide mechanistic insight into growth-survival tradeoffs. We used 24-d trials to test effects of salinity (0 – 4000 mg/L Cl-) on growth, development, survival, CORT responses, and tradeoffs among traits of larval Northern Leopard Frogs (Rana pipiens). We also tested experimentally suppressed CORT signaling to determine whether CORT signaling mediates effects of salinity and life history tradeoffs . Increased salinity reduced survival, growth, and development. Suppressing CORT signaling in conjunction with salinity reduced survival further, but also attenuated negative effects of salinity on growth and development. CORT of control larvae increased or was stable with growth and development, but decreased with growth and development for those exposed to salinity. Therefore, salinity dysregulated CORT physiology. Across all treatments, larvae that survived had higher CORT than larvae that died. By manipulating CORT signaling, we provide strong evidence that CORT physiology mediates the outcome of a growth-survival tradeoff. To our knowledge, this is the first study to concomitantly measure tradeoffs between growth and survival and experimentally link these changes to CORT physiology. Identifying mechanistic links between stressors and fitness-related outcomes is critical to enhance our understanding of tradeoffs.
Papers & Reports Evaluating Corticosterone as a Biomarker for Amphibians Exposed to Increased Salinity and Ambient Corticosterone
Authors: B J Tornabene; Blake R Hossack; E J Crespi; C W Breuner
Date: 2021-07 | Outlet: Conservation Physiolology 9(1): coab049
Salinization is harmful to amphibians and waterborne corticosterone could be a useful biomarker. Salinity was only associated with waterborne corticosterone for one of three amphibian species. Ambient corticosterone likely confounded associations and possibly influenced amphibian physiology. We provide suggestions to improve reliability of waterborne corticosterone as a biomarker of salt stress.
Papers & Reports Metal accumulation varies with life history, size, and development of larval amphibians
Authors: K L Smalling; Emily B Oja; Danielle M Cleveland; J M Davenport; Collin A Eagles-Smith; Evan HC Grant; Patrick M Kleeman; Brian J Halstead; Kenzi M Stemp; B J Tornabene; Z J Bunnell; Blake R Hossack
Date: 2021-06-26 | Outlet: Environmental Pollution 287: e117638
Amphibian larvae are commonly used as indicators of aquatic ecosystem health because they are susceptible to contaminants. However, there is limited information on how species characteristics and trophic position influence contaminant loads in larval amphibians. Importantly, there remains a need to understand whether grazers (anurans) and predators (salamanders) provide comparable information on contaminant accumulation or if they are each indicative of unique environmental processes and risks. To better understand the role of trophic position in contaminant accumulation, we analyzed composite tissues for 10 metals from larvae of multiple co-occurring anuran and salamander species from 20 wetlands across the United States. We examined how metal concentrations varied with body size (anurans and salamanders) and developmental stage (anurans) and how the digestive tract (gut) influenced observed metal concentrations. Across all wetlands, metal concentrations were greater in anurans than salamanders for all metals tested except mercury, selenium (Se), and zinc (Zn). Concentrations of individual metals in anurans decreased with increasing weight and developmental stage. In salamanders, which are predatory, metal concentrations were less correlated with weight, indicating diet played a role in contaminant accumulation. Based on batches of similarly sized whole-body larvae compared to larvae with their digestive tracts removed our results indicated that tissue type strongly affected perceived concentrations, especially for anurans (gut represented 50–90% of all metals except Se and Zn). This suggest the reliability of results based on whole body sampling could be biased by metal, larval size, and development. Overall, our data suggest that metal concentrations differs among orders (anuran and salamanders) which suggests that metal accumulation is unique to feeding behavior and potentially trophic position. To truly characterize exposure risk in wetlands, species of different life histories, sizes and developmental stages should be included in biomonitoring efforts.
Papers & Reports Demography of the Oregon spotted frog along a hydrologically modified river
Authors: J C Rowe; Adam Duarte; C A Pearl; B McCreary; P K Haggerty; J W Jones; M J Adams
Date: 2021-06-21 | Outlet: Ecosphere
Altered flow regimes can contribute to dissociation between life history strategies and environmental conditions, leading to reduced persistence reported for many wildlife populations inhabiting regulated rivers. The Oregon spotted frog (Rana pretiosa) is a threatened species occurring in floodplains, ponds, and wetlands in the Pacific Northwest with a core range in Oregon, USA. All life stages of R. pretiosa are reliant on aquatic habitats, and inundation patterns across the phenological timeline can have implications for population success. We conducted capture-mark-recapture (CMR) sampling of adult and subadult R. pretiosa at three sites along the Deschutes River downstream from two dams that regulate flows. We related the seasonal extent of inundated habitat at each site to monthly survival probabilities using a robust design CMR model. We also developed matrix projection models to simulate population dynamics into the future under current river flows. Monthly survival was strongly associated with the extent and variability of inundated habitat, suggesting some within-season fluctuations at higher water levels could be beneficial. Seasonal survival was lowest in the winter for all three sites, owing to limited water availability and the greater number of months within this season relative to other seasons. Population growth for the two river-connected sites was most strongly linked to adult survival, whereas population growth at the river-disconnected site was most strongly tied to survival in juvenile stages. This research identifies population effects of seasonally limited water and highlights conservation potential of enhancing survival of particularly influential life stages.
Papers & Reports Enigmatic Near-Extinction in a Boreal Toad Metapopulation in Northwestern Montana
Authors: Rebecca M McCaffery; R E Russell; Blake R Hossack
Outlet: Journal of Wildlife Management
North America’s protected lands harbor significant biodiversity and provide habitats where species threatened by a variety of stressors in other environments can thrive. Yet disease, climate change, and other threats are not limited by land management boundaries and can interact with conditions within protected landscapes to affect sensitive populations. We examined the population dynamics of a boreal toad (Anaxyrus boreas) metapopulation at a wildlife refuge in northwestern Montana over a 16-year period (2003-2018). We used robust design capture-recapture models to estimate male population size, recruitment, and apparent survival over time and in relation to the amphibian chytrid fungus, Batrachochytrium dendrobatidis. We estimated female population size in years with sufficient captures. Finally, we examined trends in male and female toad body size and condition. We found no evidence of an effect of disease or time on male toad survival but detected a strong negative trend in recruitment of new males to the population. Estimates of male and female abundance decreased dramatically over time. Body size of males and females was inversely related to estimated population size, consistent with reduced recruitment to replace adults, but body condition of adult males was only weakly associated with abundance. Together, these results describe the demography of a near-extinction event, and point to dramatic decreases in the recruitment of new individuals to the breeding population as the cause of this decline. We surmise that processes related to the restoration of historical hydrology within the refuge adversely affected amphibian breeding habitat, and that these changes interacted with disease, life history, and other factors to restrict the recruitment of new individuals to the breeding population over time. Our results point to challenges in understanding and predicting drivers of population change and highlight that current metrics for assessing population status can have limited predictive ability.
Papers & Reports Monitoring wetland water quality related to livestock grazing in amphibian habitats
Authors: K L Smalling
Date: 2021-01-13 | Outlet: Environmental Monitoring and Assessment 193, 58
Land use alteration such as livestock grazing can affect water quality in habitats of at-risk wildlife species. Data from managed wetlands are needed to understand levels of exposure for aquatic life stages and monitor grazing-related changes afield. We quantified spatial and temporal variation in water quality in wetlands occupied by threatened Oregon spotted frog (Rana pretiosa) at Klamath Marsh National Wildlife Refuge in Oregon, US. We used analyses for censored data to evaluate the importance of habitat type and grazing history in predicting concentrations of nutrients, turbidity, fecal indicator bacteria (FIB; total coliforms, E. coli, and enterococci), and estrogenicity, an indicator of estrogenic activity. Nutrients (orthophosphate and ammonia) and enterococci varied over time and space, while E. coli, total coliforms, turbidity, and estrogenicity were more strongly associated with local livestock grazing metrics. Turbidity was correlated with several grazing-related constituents and may be particularly useful for monitoring water quality in landscapes with livestock use. Concentrations of orthophosphate and estrogenicity were elevated at several sites relative to published health benchmarks, and their potential effects on R. pretiosa warrant further investigation. Our data provided an initial assessment of potential exposure of amphibians to grazing related constituents in western US wetlands.
Papers & Reports Climate’s cascading effects on disease, predation, and hatching success in Anaxyrus canorus, the threatened Yosemite toad
Authors: W J Sadinski; A L Gallant; J Cleaver
Date: 2020-09-01 | Outlet: Global Ecology and Conservation
The U.S. Fish and Wildlife Service listed Anaxyrus canorus, the Yosemite toad, as federally threatened in 2014 based upon reported population declines and vulnerability to global-change factors. A. canorus lives only in California’s central Sierra Nevada at medium to sub-alpine elevations. Lands throughout its range are protected from development, but climate and other global-change factors potentially can limit populations. A. canorus reproduces in ultra-shallow wetlands that typically hydrate seasonally via melting of the winter snowpack. Lesser snowpacks in drier years can render wetland water volumes and hydroperiods insufficient to allow for successful breeding and reproduction. Additionally, breeding and embryogenesis occur very soon after wetlands thaw when overnight temperatures can be below freezing. Diseases, such as chytridiomycosis, which recently decimated regional populations of ranid species, also might cause declines of A. canorus populations. However, reported studies focused on whether climate interacts with any pathogens to affect fitness in A. canorus have been scarce. We investigated effects of these factors on A. canorus near Tioga Pass from 1996 to 2001. We found breeding subpopulations were distributed widely but inconsistently among potentially suitable wetlands and frequently consisted of small numbers of adults. We occasionally observed small but not alarming numbers of dead adults at breeding sites. In contrast, embryo mortality often was notably high, with the majority of embryos dead in some egg masses while mortality among coincidental Pseudacris regilla (Pacific treefrog) embryos in deeper water was lower. After sampling and experimentation, we concluded that freezing killed A. canorus embryos, especially near the tops of egg masses, which enabled Saprolegnia diclina (a water mold [Oomycota]) to infect and then spread through egg masses and kill more embryos, often in conjunction with predatory flatworms (Turbellaria spp.). We also concluded exposure to ultraviolet-B radiation did not play a role. Based upon our assessments of daily minimum temperatures recorded around snow-off during years before and after our field study, the freezing potential we observed at field sites during embryogenesis might have been commonplace beyond the years of our field study. However, interactions among snow quantity, the timing of snow-off, and coincidental air temperatures that determine such freezing potential make projections of future conditions highly uncertain, despite overall warming trends. Our results describe important effects from ongoing threats to the fitness and abundance of A. canorus via reduced reproduction success and demonstrate how climate conditions can exacerbate effects from pathogens to threaten the persistence of amphibian populations.
Papers & Reports A National-Scale Assessment of Mercury Bioaccumulation in United 2 States National Parks Using Dragonfly Larvae As Biosentinels 3 through a Citizen-Science Framework
Authors: Collin A Eagles-Smith; J J Willaker; S J Nelson; C M Flanagan; D P Krabbenhoft; C Y Chen; J T Ackerman; Evan HC Grant; David S Pilliod
Outlet: Environmental Science and Technology
ABSTRACT: We conducted a national-scale assessment of mercury (Hg) bioaccumulation in aquatic ecosystems using dragonfly
larvae as biosentinels by developing a citizen-science network to facilitate biological sampling. Implementing a carefully designed
sampling methodology for citizen scientists, we developed an effective framework for a landscape-level inquiry that might otherwise
be resource limited. We assessed the variation in dragonfly Hg concentrations across >450 sites spanning 100 United States National
Park Service units and examined intrinsic and extrinsic factors associated with the variation in Hg concentrations. Mercury
concentrations ranged between 10.4 and 1411 ng/g of dry weight across sites and varied among habitat types. Dragonfly total Hg
(THg) concentrations were up to 1.8-fold higher in lotic habitats than in lentic habitats and 37% higher in waterbodies, with
abundant wetlands along their margins than those without wetlands. Mercury concentrations in dragonflies differed among families
but were correlated (R2 > 0.80) with each other, enabling adjustment to a consistent family to facilitate spatial comparisons among
sampling units. Dragonfly THg concentrations were positively correlated with THg in both fish and amphibians from the same
locations, indicating that dragonfly larvae are effective indicators of Hg bioavailability in aquatic food webs. Collectively, this
continental-scale study demonstrates the utility of dragonfly larvae for estimating the potential mercury risk to fish and wildlife in
aquatic ecosystems and provides a framework for engaging citizen science as a component of landscape Hg monitoring programs.
Papers & Reports A Synthesis of Evidence of Drivers of Amphibian Declines
Authors: Evan HC Grant; David AW Miller; Erin Muths
Outlet: Herpetologica xx: xxx-xxx
ABSTRACT: Early calls for robust long-term time series of amphibian population data, stemming from discussion following the first World Congress of Herpetology, are now being realized after 25 yr of focused research. Inference from individual studies and locations have contributed to a basic consensus on drivers of amphibian declines. Until recently there were no large-scale syntheses of long-term time series data to test hypotheses about the generality of factors driving population dynamics at broad spatial scales. Through the U.S. Geological Survey’s Powell Center for Analysis and Synthesis, we brought together a group of scientists to elucidate mechanisms underlying amphibian declines in North America and Europe. We used time series of field data collected across dozens of study areas to make inferences with these combined data using hierarchical and spatial models. We bring together results from four syntheses of these data to summarize our state of knowledge of amphibian declines, identify commonalities that suggest further avenues of study, and suggest a way forward in addressing amphibian declines—by looking beyond specific drivers to how to achieve stability in remaining populations. The common thread of the syntheses is that declines are real but not ubiquitous, and that multiple factors drive declines but the relative importance of each factor varies among species, populations and regions. We also found that climate is an important driver of amphibian population dynamics. However, the direction and magnitude of sensitivity to change vary among species in ways unlikely to explain overall rates of decline. Thirty years after the initial identification of a major catastrophe for global biodiversity, the scientific community has empirically demonstrated the reality of the problem, identified putative causes, provided evidence of their impacts, invested in broader scale actions, and attempted meta-analyses to search out global drivers. We suggest an approach that focuses on key demographic rates that may improve amphibian population trends at multiple sites across the landscape.
Papers & Reports Amphibian responses in the aftermath of extreme climate events
Authors: G Bucciarelli; M Clark; K S Delaney; S Riley; H Shaffer; R N Fisher; R L Honeycutt; L Kats
Date: 2020-02-25 | Outlet: Scientific Reports 10:3409
Climate change-induced extinctions are estimated to eliminate one in six known species by the end
of the century. One major factor that will contribute to these extinctions is extreme climatic events.
Here, we show the ecological impacts of recent record warm air temperatures and simultaneous peak
drought conditions in California. From 2008–2016, the southern populations of a wide-ranging endemic
amphibian (the California newt, Taricha torosa) showed a 20% reduction to mean body condition and
significant losses to variation in body condition linked with extreme climate deviations. However,
body condition in northern populations remained relatively unaffected during this period. Range-wide
population estimates of change to body condition under future climate change scenarios within the
next 50 years suggest that northern populations will mirror the loss of body condition recently observed
in southern populations. This change is predicated on latter 21st century climate deviations that
resemble recent conditions in Southern California. Thus, the ecological consequences of climate change
have already occurred across the warmer, drier regions of Southern California, and our results suggest
that predicted climate vulnerable regions in the more mesic northern range likely will not provide
climate refuge for numerous amphibian communities.
Papers & Reports Amphibian chytrid prevalence on boreal toads in SE Alaska and NW British Columbia: tests of habitat, life stages, and temporal trends
Authors: Blake R Hossack; M J Adams; R K Honeycutt; J Belt; S Pyare
Date: 2020 | Outlet: Diseases of Aquatic Organisms 137:159-165
Tracking and understanding variation in pathogens such as Batrachochytrium dendrobatidis
(Bd), the agent of amphibian chytridiomycosis, which has caused population declines
globally, is a priority for many land managers. However, relatively little sampling of amphibian
communities has occurred at high latitudes. We used skin swabs collected during 2005?2017 from
boreal toads Anaxyrus boreas (n = 248), in southeast Alaska (USA; primarily in and near Klondike
Gold Rush National Historical Park [KLGO]) and northwest British Columbia (Canada) to determine
how Bd prevalence varied across life stages, habitat characteristics, local species richness,
and time. Across all years, Bd prevalence peaked in June and was >3 times greater for adult toads
(37.5%) vs. juveniles and metamorphs (11.2%). Bd prevalence for toads in the KLGO area, where
other amphibian species are rare or absent, was highest from river habitats (55.0%), followed by
human-modified upland wetlands (32.3%) and natural upland wetlands (12.7%)—the same rankorder
these habitats are used for toad breeding. None of the 12 Columbia spotted frogs Rana
luteiventris or 2 wood frogs R. sylvatica from the study area tested Bd-positive, although all were
from an area of low host density where Bd has not been detected. Prevalence of Bd on toads in the
KLGO area decreased during 2005?2015. This trend from a largely single-species system may be
encouraging or concerning, depending on how Bd is affecting vital rates, and emphasizes the
need to understand effects of pathogens before translating disease prevalence into management
actions.
Papers & Reports Contrasting demographic responses of toad populations to regionally synchronous pathogen (Batrachochytrium dendrobatidis) dynamics
Authors: Blake R Hossack; R E Russell; Rebecca M McCaffery
Date: 2020 | Outlet: Biological Conservation 241: 108373
Batrachochytrium dendrobatidis (Bd), a fungal pathogen that causes amphibian chytridiomycosis, has been implicated in population declines globally. To better understand how Bd affects survival and how threats vary spatially and temporally, we conducted long-term (range: 9–13 yrs) capture-recapture studies of boreal toads (Anaxyrus boreas) from three similar communities in western Montana. We also estimated temporal and spatial variation in population-level Bd prevalence among populations and the potential role of co-occurring Columbia spotted frogs (Rana luteiventris) in driving infection dynamics. Hierarchical models that accounted for detection uncertainty revealed Bd reduced apparent survival in one population that declined, was unassociated with survival in one stationary population, and was associated with increased survival in one population that is near extirpation. Despite different effects of Bd on hosts, pathogen prevalence was similar and synchronous across the populations separated by 111 – 176 km. Variation in Bd prevalence was driven partly by seasonal temperatures, but opposite the direction expected. Bd prevalence also decreased sharply over time across all populations, unrelated to trends in temperature, boreal toad survival, or infection dynamics of co-occurring Columbia spotted frogs. Toad Bd prevalence increased when frog abundance was high, consistent with an amplification effect. However, Bd prevalence of toads decreased as Bd prevalence of spotted frogs increased, consistent with a dilution effect. Our results reveal surprising variation in responses to Bd and show pathogen prevalence is not predictive of survival or population risk, and they illustrate the complexity in understanding disease dynamics across multiple populations.
Papers & Reports A statistical forecasting approach to metapopulation viability analysis
Authors: P E Howell; Blake R Hossack; Erin Muths; Brent H Sigafus; A Chenevert-Steffler; R B Chandler
Date: 2020 | Outlet: Ecological Applications 2020:e02038
Conservation of at-risk species is aided by reliable forecasts of the consequences of environmental change and management actions on population viability. Forecasts from conventional population viability analysis (PVA) are made using a two-step procedure in which parameters are estimated, or elicited from expert opinion, and then plugged into a stochastic population model without accounting for parameter uncertainty. Recently-developed statistical PVAs differ because forecasts are made conditional on models that are fitted to empirical data. The statistical forecasting approach allows for uncertainty about parameters, but it has rarely been applied in metapopulation contexts where spatially-explicit inference is needed about colonization and extinction dynamics and other forms of stochasticity that influence metapopulation viability. We conducted a statistical metapopulation viability analysis (MPVA) using 11 years of data on the federally-threatened Chiricahua leopard frog to forecast responses to landscape heterogeneity, drought, environmental stochasticity, and management. We evaluated several future environmental scenarios and pond restoration options designed to reduce extinction risk. Forecasts over a 50-yr time horizon indicated that metapopulation extinction risk was <8% for all scenarios, but uncertainty was high. Without pond restoration, extinction risk is forecasted to be 5.6% (95% CI: 0?60%) by year 2060. Restoring six ponds by increasing hydroperiod reduced extinction risk to 1.0% (0 ? 11%) in year 2060. We found little evidence that drought influences metapopulation viability when managers have the ability to maintain ponds that hold water throughout the year and are free of invasive species. Our study illustrates the utility of the spatially explicit statistical forecasting approach to MPVA in conservation planning efforts.
Papers & Reports Seeking shelter from the storm: Conservation and management of imperiled species in a changing climate.
Authors: Susan C Walls; William J Barichivich; J Chandler; A M Meade; M Milinichik; K M O'Donnell; M E Owens; T Peacock; J Reinman; O E Wetsch
Date: 2019-05-30 | Outlet: Ecology and Evolution 9(12): 7122-7133.
Climate change is anticipated to exacerbate the extinction risk of species whose persistence is already compromised by habitat loss, invasive species, disease, and other stressors. In coastal areas of the southeastern United States, many imperiled vertebrates are vulnerable to hurricanes, which climate models predict to become more severe in the 21st century. Despite this escalating threat, explicit adaptation strategies that address hurricane threats, in particular, and climate change more generally, are largely underrepresented in recovery planning and implementation. Our purpose herein is to provide a basis for stronger emphasis on strategic planning for imperiled species facing the increasing threat of catastrophic hurricanes. Our reasoning comes from observations of short-term environmental and biological impacts of Hurricane Michael, which impacted the Gulf Coast of the southeastern USA in October 2018. During this storm, St. Marks National Wildlife Refuge, located along the northern Gulf of Mexico?s coast in the panhandle region of Florida, experienced storm surge that was 2.3 to 3.3 m above sea level. Storm surge pushed sea water into some ephemeral freshwater ponds used for breeding by the federally-threatened Frosted Flatwoods Salamander (Ambystoma cingulatum). After the storm, specific conductance across all ponds varied from 80 to 23,100 ?S/cm,compared to 75 to 445 uS/cm in Spring 2018. For those overwashed wetlands that were measured in both Spring and Fall 2018, post-hurricane conductance observations averaged nearly 100 times greater than in the previous Spring, setting the stage for varying population responses across this coastal landscape. Importantly, we found live individual flatwoods salamanders at both overwashed and non-overwashed sites, although we cannot yet assess the demographic consequences of this storm. We outline actions that could be incorporated into climate adaptation strategies and recovery planning for imperiled species, like A. cingulatum, that are associated with freshwater coastal wetlands in hurricane-prone regions.
Papers & Reports Persistent salinization of surface and groundwater resources from legacy energy development in the Prairie Pothole Region
Authors: T Preston; Chauncey W Anderson; J N Thamke; Blake R Hossack; K J Skalak; I M Cozzarelli,
Outlet: Science of the Total Environment 690:522-533
Papers & Reports Drought-mediated extinction of an arid-land amphibian: insights from a spatially explicit dynamic occupancy model
Authors: E R Zylstra; D E Swann; Blake R Hossack; Erin Muths; R J Steidl
Outlet: Ecological Applications 29: e01859
Understanding how natural and anthropogenic processes affect population dynamics of species with patchy distributions is critical to predicting their responses to environmental changes. Despite considerable evidence that demographic rates and dispersal patterns vary temporally in response to an array of biotic and abiotic processes, few applications of metapopulation theory have sought to explore factors that explain spatio-temporal variation in extinction or colonization rates. To facilitate exploring these factors, we extended a spatially explicit model of metapopulation dynamics to create a framework that requires only binary presence-absence data, makes few assumptions about the dispersal process, and accounts for imperfect detection. We apply this framework to 22 years of biannual survey data for lowland leopard frogs, Lithobates yavapaiensis, an amphibian that inhabits arid stream systems in the southwestern U.S. and northern Mexico. Our results highlight the importance of accounting for factors that govern temporal variation in transition probabilities, as both extinction and colonization rates varied with hydrologic conditions. Specifically, local extinctions were more frequent during drought periods, particularly at sites without reliable surface water. Colonization rates increased when larval and dispersal periods were wetter than normal, which increased the probability that potential emigrants metamorphosed and reached neighboring sites. Extirpation of frogs from one watershed during a period of severe drought demonstrated the influence of site-level features, as frogs persisted only in areas where most sites held water consistently and where the amount of sediment deposited from high-elevation wildfires was low. Application of our model provided novel insights into how climate-related processes affected the distribution and population dynamics of an arid-land amphibian. The approach we describe has application to a wide array of species that inhabit patchy environments, can improve our understanding of factors that govern metapopulation dynamics, and can inform strategies for conservation of imperiled species.
Papers & Reports Managing the trifecta of disease, climate, and contaminants: Searching for robust choices under multiple sources of uncertainty
Authors: K L Smalling; Collin A Eagles-Smith; R A Katz; Evan HC Grant
Date: 2019-05-30 | Outlet: Biological Conservation 236: 153-161
Amphibian populations are exposed to multiple stressors, with potential for synergistic effects. These synergies can increase uncertainty in our ability to characterize the effects of each stressor and to understand the degree to which their effects interact to impact population processes. This uncertainty challenges our ability to identify appropriate management alternatives. Finding solutions that are robust to these uncertainties can improve management when knowledge is absent or equivocal and identify critical knowledge gaps. Bayesian Belief Networks (BBNs) are probabilistic graphical models that explicitly account for various sources of uncertainty and are used increasingly by environmental practitioners because of their broad applicability to ecological risk assessments. BBNs allow the user to: 1) generate a conceptual model to link actions to outcomes, 2) use a variety of source data (empirical or expert opinion), 3) explore robust management strategies under uncertainty, 4) use sensitivity analysis to identify opportunities for developing new management actions, and 5) guide the design of data collection for monitoring to improve management decisions. BBNs contribute considerably to environmental research and management because they are transparent and treat uncertainty explicitly. Because of the high level of uncertainty in stressor response, we developed a BBN to conceptually evaluate the effects of potential management actions on amphibian populations exposed to disease, environmental contaminants, and increasingly frequent and severe droughts
Papers & Reports Challenges in complementing data from ground-based sensors with satellite-derived products to measure ecological changes in relation to climate?lessons from temperate wetland-upland landscapes
Authors: A L Gallant; W J Sadinski; J Brown; G B Senay; M R Roth
Date: 2018-03-16 | Outlet: Sensors 18(3)880
Assessing climate-related ecological changes across spatiotemporal scales meaningful to resource managers is challenging because no one method reliably produces essential data at both fine and broad scales. We recently confronted such challenges while integrating data from ground- and satellite-based sensors for an assessment of four wetland-rich study areas in the U.S. Midwest. We examined relations between temperature and precipitation and a set of variables measured on the ground at individual wetlands and another set measured via satellite sensors within surrounding 4 km2 landscape blocks. At the block scale, we used evapotranspiration and vegetation greenness as remotely sensed proxies for water availability and to estimate seasonal photosynthetic activity. We used sensors on the ground to coincidentally measure surface-water availability and amphibian calling activity at individual wetlands within blocks. Responses of landscape blocks generally paralleled changes in conditions measured on the ground, but the latter were more dynamic, and changes in ecological conditions on the ground that were critical for biota were not always apparent in measurements of related parameters in blocks. Here, we evaluate the effectiveness of decisions and assumptions we made in applying the remotely sensed data for the assessment and the value of integrating observations across scales, sensors, and disciplines.
Papers & Reports Multi-year data from satellite- and ground-based sensors show details and scale matter in assessing climate's effects on wetland surface water, amphibians, and landscape conditions
Authors: W J Sadinski; A L Gallant; M Roth; J Brown; G Senay; W Brininger; P M Jones; J Stoker
Date: 2018-09-07 | Outlet: PLoS ONE 13(9): e0201951
Long-term, interdisciplinary studies of relations between climate and ecological conditions on wetland-upland landscapes have been lacking, especially studies integrated across scales meaningful for adaptive resource management. We collected data in situ at individual wetlands, and via satellite for surrounding 4-km2 landscape blocks, to assess relations between annual weather dynamics, snow duration, phenology, wetland surface-water availability, amphibian presence and calling activity, greenness, and evapotranspiration in four U.S. conservation areas from 2008 to 2012. Amid recent decades of relatively warm growing seasons, 2012 and 2010 were the first and second warmest seasons, respectively, dating back to 1895. Accordingly, we observed the earliest starts of springtime biological activity during those two years. In all years, early-season amphibians first called soon after daily mean air temperatures were ? 0°C and snow had mostly melted. Similarly, satellite-based indicators suggested seasonal leaf-out happened soon after snowmelt and temperature thresholds for plant growth had occurred. Daily fluctuations in weather and water levels were related to amphibian calling activity, including decoupling the timing of the onset of calling at the start of season from the onset of calling events later in the season. Within-season variation in temperature and precipitation also was related to vegetation greenness and evapotranspiration, but more at monthly and seasonal scales. Wetland water levels were moderately to strongly associated with precipitation and early or intermittent wetland drying likely reduced amphibian reproduction success in some years, even though Pseudacris crucifer occupied sites at consistently high levels. Notably, satellite-based indicators of landscape water availability did not suggest such consequential, intra-seasonal variability in wetland surface-water availability. Our cross-disciplinary data show how temperature and precipitation interacted to affect key ecological relations and outcomes on our study landscapes. These results demonstrate the value of multi-year studies and the importance of scale for understanding actual climate-related effects in these areas.
Papers & Reports Effects of Persistent Energy-related Brine Contamination on Amphibian Abundance in National Wildlife Refuge Wetlands
Authors: Blake R Hossack; K L Smalling; Chauncey W Anderson; T Preston; I M Cozzarelli,; R K Honeycutt
Date: 2018 | Outlet: Biological Conservation 228:36–43