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174 record(s) found.

Papers & Reports Host pathogen metapopulation dynamics suggest high elevation refugia for boreal toads
Authors: Brittany A Mosher; Larissa L Bailey; Erin Muths; Kathryn P Huyvaert
Date: 2018 | Outlet: Ecological Applications
Emerging infectious diseases are an increasingly common threat to wildlife. Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is an emerging infectious disease that has been linked to amphibian declines around the world. Few studies exist that explore amphibian-Bd dynamics at the landscape scale, limiting our ability to identify which factors are associated with variation in population susceptibility and to develop effective in situ disease management. Declines of boreal toads (Anaxyrus boreas boreas) in the Southern Rocky Mountains are largely attributed to chytridiomycosis but variation exists in local extinction of boreal toads across this metapopulation. Using a large-scale historic dataset, we explored several potential factors influencing disease dynamics in the boreal toad-Bd system: geographic isolation of populations, amphibian community richness, elevational differences, and habitat permanence. We found evidence that boreal toad extinction risk was lowest at high elevations where temperatures may be sub-optimal for Bd growth and where small boreal toad populations may be below the threshold needed for efficient pathogen transmission. In addition, boreal toads were more likely to recolonize high elevation sites after local extinction, again suggesting that high elevations may provide refuge from disease for boreal toads. We illustrate a modeling framework that will be useful to natural resource managers striving to make decisions in amphibian-Bd systems.
Papers & Reports Status of the Threatened Chiricahua Leopard Frog and Conservation Challenges in Sonora, Mexico, with Notes on Other Ranid Frogs and Non-native Predators
Authors: James C Rorabaugh; Blake R Hossack; Erin Muths; Brent H Sigafus; J A Lemos-Espinal
Date: 2018-04-30 | Outlet: Herpetological Conservation and Biology 13(1):17–32
In North America, ranid frogs (Ranidae) have experienced larger declines than any other amphibian family, particularly species native to the southwestern USA and adjacent Mexico; however, our knowledge of their conservation status and threats is limited in Mexico. We assessed the status of the federally-threatened (USA) Chiricahua Leopard Frog (Lithobates chiricahuensis) in Sonora, Mexico, based on a search of museum specimens, published records, unpublished accounts, and surveys of 84 sites within the geographical and elevational range of the species from 2000-2016. We also provide information on occurrence of three other native ranid frog species encountered opportunistically during our surveys. The Chiricahua Leopard Frog is known in Sonora from only 20 historical (pre-2000) localities. Searches of three historical sites from 2000-2016 did not reveal any Chiricahua Leopard Frogs; however, we found it at three previously undocumented sites in 2016, all near Cananea. To our knowledge, these records are the first observations of Chiricahua Leopard Frogs in Sonora since 1998. Differences in conservation status between the USA and Sonora are likely due to differing magnitude and distribution of threats and a comparatively aggressive recovery program in the USA. For example, key non-native predators important in the decline of the Chiricahua Leopard Frog are much less widespread in Sonora compared to the USA Southwest, but there are fewer protections and recovery actions for the frog in Sonora than in the USA. Additional surveys for the Chiricahua Leopard Frog and other amphibians in Sonora should be a priority to fully assess threats and conservation status.
News & Stories Interpretive sign highlighting the federally threatened Chiricahua Leopard Frog debuts at Buenos Aires National Wildlife Refuge
Authors: Erin Muths; Brent H Sigafus; Blake R Hossack; P E Howell
August 21, 2017

An interpretive sign was installed on August 1st, 2017 near the headquarters and visitor information office at Buenos Aires National Wildlife Refuge (BANWR, Sasabe, Arizona). The sign provides information on the federally-threatened Chiricahua Leopard Frog (Lithobates chiricahuensis) and is located next to an example of typical habitat (a cienaga). In addition to the biology and behavior of this desert frog, the sign gives a friendly reminder to brake for amphibians on Refuge roads, especially during the summer monsoon season when amphibians are more likely to be moving between habitats; in the desert, as for many animals, the cienagas and cattle tanks retain water and are key refuges during drought.

This interpretive sign, the first highlighting an amphibian on BANWR, was originally designed to educate visitors about the Chiricahua Leopard Frog, but the sign has become a template and an inspiration for further educational efforts. Additional signs are in the works at BANWR to provide interpretive information along a planned nature walk near Refuge headquarters and at the flight pen for the federally endangered Masked Bobwhite Quail. Based on the design of the Chiricahua Leopard Frog sign, interpretive information is being created to highlight all of the diverse flora and fauna at BANWR and give the visitor a better idea of the complex and interconnected lives of the organisms they might encounter as they enjoy the scenery and arid landscape of the Refuge.

The Chiricahua Leopard Frog interpretive sign was a concept initiated during a stakeholder meeting in February 2017, at BANWR, where decision science methods were applied to discuss refuge priorities (e.g., Chiricahua Leopard Frog conservation, general refuge management). Stakeholders included personnel from U.S. Fish and Wildlife Service, Arizona Game and Fish Department, U.S. Geological Survey, and the University of Georgia. The sign was designed through collaborative effort among those entities and funded via Jones-Lovich grant in Southwestern Herpetology from the Herpetologists' League. Work on declining amphibians at BANWR and the Borderlands was initiated by Cecil Schwalbe (USGS, ARMI-retired) and has been continued by Brent Sigafus, Blake Hossack and Erin Muths (Rocky Mountain and Southwest ARMI).

Papers & Reports Factors Influencing Anuran Wetland Occupancy in an Agricultural Landscape
Authors: J Swanson; Clay L Pierce; S Dinsmore; Kelly L Smalling; M Vandever; T Steward; Erin Muths
Date: 2018 | Outlet: Herpetologica
Habitat disturbance is an important cause of global amphibian declines, with especially strong effects in areas of high agricultural use. Determining the influence of site characteristics on amphibian presence and success is vital to developing effective conservation strategies. We used occupancy analysis to estimate presence of four anuran species at wetlands in northern Iowa as a function of eight environmental covariates hypothesized to affect occupancy: fish abundance, salamander abundance, invertebrate density, aquatic vegetative cover, wetland area, atrazine concentration in water, surrounding crop land use, and an overall wetland health score. We surveyed 27 wetlands in 2015 and 2016. Wetland site occupancy for all species in our study ranged from https://0.23 (Hyla spp. tadpoles) to https://0.95 (L. pipiens adults), indicating agricultural wetlands can provide refuge or habitat for amphibians. Detection probabilities ranged from https://0.13 (P. maculata adults) to https://0.61 (A. americanus adults). Fish abundance, percent of surrounding cropland within 500 m of the wetland, and salamander abundance were among the variables best supported in our model sets although their estimated effects were weak. The direction of predicted effects varied by species and life stage.Although we did not find strong evidence that the environmental factors we measured influenced amphibian populations in our study, we provide insight for managers and researchers on how amphibians use a landscape modified by agriculture.
Papers & Reports Identifying Species Conservation Strategies to Reduce Disease-Associated Declines
Authors: B D Gerber; S J Converse; Erin Muths; H Crockett; Brittany A Mosher; Larissa L Bailey
Date: 2017 | Outlet: Conservation Letters
Emerging infectious diseases (EIDs) are a salient threat to many animal taxa, causing local and global extinctions, altering communities and ecosystem function. The EID chytridiomycosis is a prominent driver of amphibian declines, which is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd). To guide conservation policy, we developed a predictive decision-analytic model that combines empirical knowledge of host-pathogen metapopulation dynamics with expert judgment regarding effects of management actions, to select from potential conservation strategies. We apply our approach to a boreal toad (Anaxyrus boreas boreas) and Bd system, identifying optimal strategies that balance tradeoffs in maximizing toad population persistence and landscape-level distribution, while considering costs. The most robust strategy is expected to reduce the decline of toad breeding sites from 53% to 21% over 50 years. Our findings are incorporated into management policy to guide conservation planning. Our online modeling application provides a template for managers of other systems challenged by EIDs.
Papers & Reports Evaluation of wetland mitigation in the Geater Yellowstone Ecosystem: Wildlife population and community responses
Authors: L Swartz; Erin Muths; Blake R Hossack
Date: 2017-12 | Outlet: Wyoming Department of Transportation
The reconstruction of US Highway 26/287 over Togwotee Pass, Wyoming, impacted or caused the loss of natural wetlands. To comply with U.S. Army Corps of Engineers permit conditions, the Wyoming Department of Transportation (WYDOT) recently completed construction or restoration of 38 mitigation wetlands along the Highway 26-287 corridor and at the aggregate pit site at the U.S. Forest Service Blackrock Ranger Station. This study provides WYDOT information on differences among wetlands created to mitigate for wetland loss (n=10), wetlands impacted but not destroyed (n=7), and natural wetlands (n=16) relative to various aspects of wildlife that use these habitats. We compare characteristics of amphibians, a pathogenic fungus, invertebrates, and birds. Created wetlands in this study area were significantly shallower than natural and impacted wetlands and had shorter hydroperiods; but impacted wetlands were similar in physical habitat characteristics to natural wetlands. Boreal toads (Anaxyrus boreas) rapidly colonized newly constructed wetlands and annual survival and recruitment rates were similar in created and natural wetlands. Boreal chorus frogs (Pseudacris maculata) were less than half as likely to occupy created wetlands as natural and impacted wetlands but population sizes were high in at least one created wetland. Barred tiger salamanders (Ambystoma mavortium) occurred in natural and impacted wetlands at similar levels, but we observed reproduction by Columbia spotted frogs (Rana luteiventris) at only one created wetland-they were common in natural and impacted wetlands. There was no difference in the prevalence of the pathogenic fungus between created and natural wetlands. Species richness of invertebrates was lower in constructed wetlands than in natural and impacted wetlands and the community composition of invertebrates differed among wetland types. Communities in created wetlands were more likely to be dominated by flying species compared to communities in natural wetlands that had more passive dispersers such as snails and clams. We recorded bird calls in two created and two natural wetlands; species richness was similar but some riparian specialists (e.g., willow flycatcher, Wilson's warbler) were not detected at either created wetland. Our results suggest that wetland creation can be an important tool for conserving wetland-dependent wildlife. Understanding how animals use created wetlands sites is a critical component to understanding the efficacy of mitigation efforts and determining alternative (e.g., earlier) endpoints. This report highlights characteristics in created sites that are advantageous to species that are perhaps non-focal, but important members of the natural community. The data presented here provide support for earlier endpoints for determining success in created wetlands and a baseline for continued monitoring of these or other created sites.
News & Stories New graduate student starts at Colorado State University, funded jointly by ARMI, Colorado State University, and Rocky Mountain National Park.
Authors: Erin Muths
June 20, 2017

A new graduate student has started work on boreal toads this summer in Rocky Mountain National Park (RMNP). John Crockett completed his undergraduate degree at Colby College and successfully garnered a funded graduate position in Larissa Bailey's lab at Colorado State University (CSU). He will be working with ARMI scientist Erin Muths and Larissa Bailey to examine factors that influence boreal toad survival from egg to one year old toads. During the past 15 years, breeding by boreal toads has been documented at only six sites within RMNP and in 2016 breeding occurred in only four of these remaining sites. Batrachochytrium dendrobatidis, a fungal pathogen which causes a fatal skin disease in amphibians, has been credited as the cause of the recent and rapid declines of boreal toads in RMNP and has been identified at three of these sites. Quantifying breeding success and understanding factors that impact survival in early life stages of toads are poorly known aspects of their ecology. One of these factors is the potential negative interaction between trout and aquatic stages of toads (egg and tadpoles). Laboratory evidence suggests that trout will "taste" tadpoles, while not lethal, it does effect survival. A behavioral component to this project will examine interactions between trout and aquatic stages in the field. In addition to newly collected data on behavior, egg deposition, hatching success, and metamorph survival, this jointly-funded project will capitalize on long-term existing data from Muths' lab and RMNP. We anticipate that this information will help us understand factors that impact early life stages of toads and identify situations where we may be able to intervene and improve survival rates, thus informing management strategies and contributing to conservation of the toad.

ARMI in Action Boreal toad considered for listing by FWS
Authors: Erin Muths
General location: southern Rocky Mountains
ARMI in Action Boreal toad conservation plan for Colorado updated
Authors: Erin Muths; Larissa L Bailey; C Converse; B D Gerber
General location: southern Rocky Mountains
Papers & Reports Amphibians, pesticides, and the amphibian chytrid fungus in resetored weltands in agricultural landscapes
Authors: Rebecca A Reeves; Clay L Pierce; M Vandever; Erin Muths; Kelly L Smalling
Date: 2017 | Outlet: Herpetological Conservation and Biology 12:68-77
Information on interactions between pesticide exposure and disease prevalence in amphibian populations is limited, especially from field data.Exposure to certain herbicides and insecticides has the potential to decrease immune response in frogs which can potentially lead to an increased abundance of Batrachochytrium dendrobatidis (Bd) zoospores on individuals and in the https://wetlands.In contrast, exposure to certain fungicides can decrease Bd abundance on frog skin. We examined the relationships between the abundance of Bd on the skin of individual Boreal Chorus Frogs(Pseudacris maculata) and the concentrations of pesticides in the water and in frog tissue at six agriculturally dominated wetlands in Iowa, USA
Papers & Reports Informing recovery in a human-transformed landscape: drought-mediated coexistence alters population trends of an imperiled salamander and invasive predators
Authors: Blake R Hossack; R K Honeycutt; Brent H Sigafus; Erin Muths; C L Crawford; T R Jones,; J A Sorensen; James C Rorabaugh; Thierry C Chambert
Date: 2017-03-16 | Outlet: Biological Conservation 209 (2017) 377–394
Understanding the additive or interactive threats of habitat transformation and invasive species is critical for conservation, especially where climate change is expected to increase the severity or frequency of drought. In the arid southwestern USA, this combination of stressors has caused widespread declines of native aquatic and semi-aquatic species. Achieving resilience to drought and other effects of climate change may depend upon continued management, so understanding the combined effects of stressors is important. We used Bayesian hierarchical models fitted with 10-yrs of pond-based monitoring surveys for the federally-endangered Sonoran Tiger Salamander (Ambystoma mavortium stebbinsi) and invasive predators (fishes and American Bullfrogs, Lithobates catesbeianus) that threaten native species. We estimated trends in occupancy of salamanders and invasive predators while accounting for hydrological dynamics of ponds, then used a two-species interaction model to directly estimate how invasive predators affected salamander occupancy. We also tested a conceptual model that predicted that drought, by limiting the distribution of invasive predators, could ultimately benefit native species. Even though occupancy of invasive predators was stationary and their presence in a pond reduced the probability of salamander presence by 23%, occupancy of Sonoran Tiger Salamanders increased, annually, by 2.2%. Occupancy of salamanders and invasive predators both declined dramatically following the 5th consecutive year of drought. Salamander occupancy recovered quickly after return to non-drought conditions, while occupancy of invasive predators remained suppressed. Models that incorporated three time-lagged periods (1 to 4 yrs) of local moisture conditions confirmed that salamanders and invasive predators responded differently to drought, reflecting how life-history strategies shape responses to disturbances. The positive 10-yr trend in salamander occupancy and their rapid recovery after drought provided partial support for the hypothesis of drought-mediated coexistence with invasive predators. These results also suggest management opportunities for conservation of the Sonoran Tiger Salamander and other imperiled organisms in human-transformed landscapes.
News & Stories The 2016 ARMI meeting was held at the National Wildlife Health Center (NWHC) in Madison, Wisconsin
Authors: Erin Muths
December 01, 2016

The 2016 ARMI meeting was held at the National Wildlife Health Center (NWHC) in Madison, Wisconsin. ARMI scientists met with disease researchers from NWHC to develop a new disease strategy designed to meet the need for increased information on how aspects of the environment can be managed to understand and reduce the effect of disease on amphibian populations. Disease has been an integral part of ARMI efforts since the inception of this program when the amphibian chytrid fungus and its devastating effects on amphibians was first identified. Now, the complex topic of disease has again come to the forefront of public and scientific consciousness with the recent emergence of a number of infectious diseases such as white-nosed syndrome in bats and the salamander chytrid fungus (Batrachochytrium salamandrivorans) in amphibians. Additional topics at the meeting focused on research results, including projects as diverse as decision science, amphibian presence relative to gas and oil development, demographic estimates for a number of focal populations, international collaborations, and modelling and methods development. Synergies resulting from this cross discipline (e.g., biology, contaminants, water, disease) effort are critical to develop the knowledge base, direction and tools to effectively combat the global issue of amphibian decline.

Papers & Reports Even with forewarning, challenges remain in developing a proactive response to emerging infectious diseases
Authors: Evan HC Grant; Erin Muths; R A Katz; Stefano Canessa; Michael J Adams; Jennifer R Ballard; Lee Berger; Cheryl J Briggs; J H Coleman; M J Gray; Maria-Richetta C Hopkins; Reid N Harris; Blake R Hossack; Kathryn P Huyvaert; Jonathan E Kolby; Karen R Lips; Robert E Lovich; Hamish I McCallum; Joseph R Mendelson III; Priya Nanjappa; Deanna H Olson; Jenny G Powers; Katherine LD Richgels; Robin E Russell; Benedikt R Schmidt
Outlet: Frontiers in Ecology and Evolution
Despite calls for improving responses to emerging infectious diseases of wildlife, management is seldom considered until a disease has been detected in affected populations. Reactive approaches may limit the potential for control and increase total response costs. An alternative, proactive, management framework can identify immediate actions that reduce future impacts even before a disease is detected, as well as prepare actions conditional on disease emergence. We identify four main challenges to developing proactive management strategies for the newly discovered salamander pathogen, Batrachochytrium salamandrivorans (Bsal). Given that deep uncertainty is a hallmark of wildlife disease management and decisions are often complicated by multiple competing objectives, we advocate using decision analysis to create and evaluate trade-offs among proactive (pre-emergence) and reactive (post-emergence) management. Using principles from decision analysis, natural resources agencies and policy-makers can utilize a variety of tools to improve the development of management strategies for emerging infectious diseases.
Papers & Reports Amphibian conservation: clarifications to comments from Andreone
Authors: Erin Muths; Robert N Fisher
Date: 2017
We appreciate the review and comments from Andreone (2016) regarding our proposed alternative strategy for addressing the amphibian crisis. Andreone recognizes the utility of an incident command system approach but doubts the feasibility of implementation at an international level. We stated in our original article, however, that ‘The feasibility of our suggestion is debatable, but our point is that radically different approaches are necessary to effectively manage the largest extinction event in modern history’
Papers & Reports SURGICAL TECHNIQUE FOR THE PLACEMENT OF INTRACOELOMIC RADIO TRANSMITTERS AND EXTERNAL SILICONE PASSIVE SAMPLING DEVICES FOR NORTHERN LEOPARD FROGS (Lithobates pipiens )
Authors: T Yaw; J E Swanson; Clay L Pierce; Erin Muths; Kelly L Smalling; M Vandever; B A Zaffarano
Date: 2017 | Outlet: Journal of Herpetological Medicine and Surgery
Amphibians are excellent sentinels for contaminant exposure in prairie wetlands. Development of passive sampling devices (PSD) has greatly improved in recent years, and they present an innovative sampling technology that can potentially yield individual-specific, quantifiable data on chemical exposure. In this study, PSDs were attached to the ventral skin of 20 northern leopard frogs (Lithobates pipiens) with polypropylene sutures after radio transmitters had been surgically inserted into the coleomic cavity. After a recovery period frogs were released into the wild and located daily using radio telemetry to assess how long PSDs would remain attached in the frogs’ natural habitat. After one week, PSDs remained on 18 of the original 20 frogs. At 2 weeks 16 frogs were recovered and no PSDs remained attached. Although valuable data can be obtained over a short time period, more research will be necessary to demonstrate effectiveness of externally attaching silicone PSDs to northern leopard frogs for time periods longer than 1-2 weeks.
News & Stories ARMI scientists Blake Hossack (NOROCK), Brent Sigafus (SBSC) and Erin Muths (FORT), and ARMI post doc Thierry Chambert traveled to Sonora, Mexico, to survey for Sonoran Tiger Salamanders in May 2016
Authors: Erin Muths; Blake R Hossack; Brent H Sigafus
June 23, 2016

ARMI scientists Blake Hossack (NOROCK), Brent Sigafus (SBSC) and Erin Muths (FORT), and ARMI post doc Thierry Chambert traveled to Sonora, Mexico, to survey for Sonoran Tiger Salamanders in May. Reports existed of the presence of this salamander in Sonora, but the spatial extent of its range is unknown. The Sonoran Tiger Salamander is federally endangered in the US and is found only in the San Rafael Valley in southern Arizona. The identification of additional populations in nearby Sonora has implications for multiple conservation concerns including population biology, genetics, and disease. Data collected about its presence and abundance across the border will contribute to the identification of management objectives and subsequent implementation of conservation actions. The surveys were a collaborative effort with logistical support from Naturalia (http://www.naturalia.org.mx/) that included the expertise of Naturalia employees Daniel Toyos and Ramon Babuca. The trip also benefitted from assistance from Guillermo Molina (Instituto Tecnológico Superior De Cananea), Julio Lemos Espinal (UNAM), and students David Hurtado and Aline Estrella. Jim Rorabaugh contributed much to the trip by sharing knowledge of the Sonoran system gained from his previous expeditions focused on salamanders in Mexico. The effort was based at Rancho Los Fresnos, a Naturalia property located north of the town of Cananea and adjacent to the US–Mexico border. The group sampled a variety of sites on Rancho Los Fresnos, as well as surrounding ranches and locations to the south of Cananea. Tiger salamanders reside primarily in man-made or modified earthen stock tanks. These habitats were seined for salamanders and water samples were collected to test for environmental DNA (eDNA) from salamanders, invasive American bullfrogs, federally-threatened (USA) Chiricahua leopard frogs, and pathogens that cause amphibian diseases. Buccal swabs were collected from captured salamanders for genetic analyses (there is uncertainty in determining the difference among closely related salamanders in the field); and skin swabs were collected to test for disease (both Batrachochytrium salamandrivorans and B. dendrobatidis). This ongoing project has already produced one publication (Hossack et al. 2016. Notes on the Distribution of Tiger Salamanders (Presumed Ambystoma mavortium stebbinsi) in Sonora, Mexico. Herpetological Review 47(2): 177-180), and another is in preparation (Hossack et al. Informing recovery of an imperiled, endemic salamander: coupled dynamics and test of drought-mediated coexistence with invasive predators).

Papers & Reports Survival estimates for reintroduced populations of the Chiricahua Leopard Frog (Lithobates chiricahuensis)
Authors: P E Howell; Blake R Hossack; Erin Muths; Brent H Sigafus; Richard Chandler
Date: 2016 | Outlet: Copeia. 104.4: 824-830.
Global amphibian declines have been attributed to a number of factors including disease, invasive species, habitat degradation, and climate change. Reintroduction is one management action that is commonly used with the goal of recovering imperiled species. The success of reintroductions varies widely and evaluating their efficacy requires estimates of population viability metrics, such as underlying vital rates and trends in abundance. Although rarely quantified, assessing vital rates for recovering populations provides a more mechanistic understanding of population growth than numerical trends in population occupancy or abundance. We used three years of capture-mark-recapture data from three breeding ponds and a Cormack-Jolly-Seber model to estimate annual apparent survival for reintroduced populations of the federally-threatened Chiricahua Leopard Frog (Lithobates chiricahuensis) at the Buenos Aires National Wildlife Refuge (BANWR), in the Altar Valley, Arizona, USA. To place our results in context, we also compiled published survival estimates for other ranids. Average apparent survival of Chiricahua Leopard Frogs at BANWR was https://0.27 (95% CI [https://0.07, 0.74]) and average individual capture probability was https://0.02 (95% CI [0, 0.05]). Our apparent survival estimate for Chiricahua Leopard Frogs is lower than for most other ranids, and is not consistent with recent research that showed metapopulation viability in the Altar Valley is high. We suggest that low apparent survival may be indicative of high emigration rates. We recommend that future research should estimate emigration rates so that actual, rather than apparent, survival can be quantified to improve population viability assessments of threatened species following reintroduction efforts.
Papers & Reports Mitigating amphibian chytridiomycosis in nature
Authors: T WJ Garner; Benedikt R Schmidt; An Martel; Frank Pasmans; Erin Muths; A C Cunningham; C Weldon; Matthew C Fisher; Jaime Bosch
Date: 2016-10 | Outlet: Phil. Trans.R.Soc.B 371: 20160207. dx.doi.org/10.1098/rstb.2016.0207
Amphibians across the planet face the threat of population decline and extirpation caused by the disease chytridiomycosis. Despite consensus that the fungal pathogens responsible for the disease are conservation issues, strategies to mitigate their impacts in the natural world are, at best, nascent. Reducing risk associated with the movement of amphibians, non-amphibian vectors and other sources of infection remains the first line of defence and a primary objective when mitigating the threat of disease in wildlife. Amphibian-associated chytridiomycete fungi and chytridiomycosis are already widespread, though, and in this article we discuss options for mitigating the threats once disease emergence has occurred in wild amphibian populations.
Papers & Reports INFORMING RECOVERY OF THE ENDANGERED SONORAN TIGER SALAMANDER: 10-YEAR TRENDS IN OCCUPANCY OF SALAMANDERS, INVASIVE PREDATORS, AND THEIR CO-OCCURRENCE
Authors: Blake R Hossack; R K Honeycutt; Thierry C Chambert; Brent H Sigafus; T R Jones,; J A Sorensen; James C Rorabaugh; Erin Muths
Outlet: Unpublished Report (see https://doi.org/10.1016/j.biocon.2017.03.004)
The Sonoran Tiger Salamander (Ambystoma mavortium stebbinsi) occurs in a single valley that spans the USA-Mexico border and was listed as federally-endangered in 1997. The listing was driven by a variety of threats, including small geographic range and threats from invasive predators. The recovery plan for this subspecies requires scientifically-credible estimates of changes in occurrence of the Sonoran Tiger Salamander and invasive predators before further evaluation of the listing status. The recent completion of a 10-year (2004–2013) monitoring program, coordinated by the Arizona Game and Fish Department and the U.S. Fish and Wildlife Service, generated data sufficient to estimate (1) trends in breeding site occupancy by the Sonoran Tiger Salamander, (2) trends in occupancy of introduced predators, and (3) probability of co-occurrence between Sonoran Tiger Salamanders and invasive predators. We used Bayesian hierarchical models to estimate annual probabilities of occupancy and co-occurrence, after adjusting for imperfect detection. Our analyses showed that pond-level occupancy of Sonoran Tiger Salamanders increased by an estimated 2.2% (95% credible interval [CI] = 0.4%–3.8%) per year. Occupancy of invasive predators decreased by an estimated 0.7% (95% CI = −2.4%–0.7%) per year. In ponds with water, presence of invasive predators reduced salamander occupancy by 23.01% (95% CI = 8.72–43.73) across the 10-yr monitoring program. These results will assist in evaluating the status of the Sonoran Tiger Salamander and prioritizing management actions that are supported by defensible estimates.
Papers & Reports Potential Interactions Among Disease, Pesticides, Water Quality and Adjacent Land Cover in Amphibian Habitats in the United States
Authors: William A Battaglin; Kelly L Smalling; Chauncey W Anderson; Daniel L Calhoun; T Chestnut; Erin Muths
Date: 2016-05-24 | Outlet: Science of the Total Environment 320-332
To investigate interactions among disease, pesticides, water quality and adjacent land cover we collected samples of water, sediment, and frog tissue from 21 sites in 7 States in the United States (US) representing a variety of amphibian habitats. All samples were analyzed for > 90 pesticides and pesticide degradates, and water and frogs were screened for the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) using molecular methods. Pesticides and pesticide degradates were detected frequently in frog breeding habitats (water and sediment) as well as in frog tissue. Fungicides occurred more frequently in water, sediment, and tissue than was expected based upon their limited use relative to herbicides or insecticides. Pesticide occurrence in water or sediment was not a strong predictor of occurrence in tissue, but pesticide concentrations in tissue were correlated positively to agricultural and urban land, and negatively to forested land in 2-kilometer buffers around the sites. Bd was detected in water at 45% of sites, and on 34% of swabbed frogs. Bd detections in water were not associated with differences in land use around sites, but sites with detections had colder water. Frogs that tested positive for Bd were associated with sites that had higher total fungicide concentrations in water and sediment, but lower insecticide concentrations in sediments relative to frogs that were Bd negative. Bd concentrations on frog swabs were positively correlated to dissolved organic carbon, and total nitrogen and phosphorus, and negatively correlated to pH and water temperature.
Data were collected from a range of locations and amphibian habitats and represent some of the first field-collected information aimed at understanding the interactions between pesticides, land use, and amphibian disease. These interactions are of particular interest to conservation efforts as many amphibians live in altered habitats and may depend on wetlands embedded in these landscapes to survive.