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Historic USDA Investment in Working Lands for Wildlife is Great News for Hellbenders
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Working Lands for Wildlife will dedicate $500 million over the next five years to strengthen and expand efforts to protect wildlife and restore habitat on private agricultural and forest lands.
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NRCS Staff Support the Hellbender WLFW Program by Learning About Natural Design Principles
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NRCS staff from four states met in Western NC to tour stream restoration projects for hellbenders and get a close up look at best practices.
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News & Events
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To Restore Hellbender Habitat, a Biologist Visits the Farmers' Market
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When working to restore wildlife habitat on agricultural lands, outreach to producers can be challenging. Private Lands Biologist Mike Knoerr figured out a way to make it much more efficient.
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News & Events
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Are Hellbenders Found Downstream of the Ohio Train Derailment Really a Sign That the Water is Safe?
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Ohio authorities have called the recent capture and release of two hellbenders downstream from the site of a train derailment and toxic chemical spill a 'positive discovery,' because hellbenders are an indicator of a healthy aquatic ecosystem, but the reality is more complicated.
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News & Events
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Prevalence of Batrachochytrium dendrobatidis in Eastern Hellbender (Cryptobranchus alleganiensis) Populations in West Virginia, USA
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The eastern hellbender (Cryptobranchus alleganiensis alleganiensis) is a North American salamander species in decline throughout its range. Efforts to identify the causes of decline have included surveillance for the chytrid fungus Batrachochytrium dendrobatidis (Bd), which has been associated with global amphibian population losses. We evaluated the prevalence of Bd in 42 hellbenders at four sites in West Virginia, US, from June to September 2013, using standard swab protocols and real-time PCR. Overall prevalence of Bd was 52% (22/42; 37.7–66.6%; 95% confidence interval). Prevalence was highest in individuals with body weight ≥695 g (χ2=7.2487, df=1, P=0.007), and was higher in montane sampling sites than lowland sites (t=−2.4599, df=44, P=0.02). While increased prevalence in montane sampling sites was expected, increased prevalence in larger hellbenders was unexpected and hypothesized to be associated with greater surface area for infection or prolonged periods of exposure in older, larger hellbenders. Wild hellbenders have not been reported to display clinical disease associated with Bd; however, prevalence in the population is important information for evaluating reservoir status and risk to other species, and as a baseline for investigation in the face of an outbreak of clinical disease.
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Research
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Peer-reviewed Science
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Noninvasive Method for a Statewide Survey of Eastern Hellbenders Cryptobranchus alleganiensis Using Environmental DNA
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Traditional survey methods of aquatic organisms may be difficult, lengthy, and destructive to the habitat. Some methods are invasive and can be harmful to the target species. The use of environmental DNA (eDNA) has proven to be effective at detecting low population density aquatic macroorganisms. This study refined the technique to support statewide surveys. Hellbender presence was identified by using hellbender specific primers (cytochrome b gene) to detect eDNA in water samples collected at rivers, streams and creeks in Ohio and Kentucky with historical accounts of the imperiled eastern hellbender (Cryptobranchus a. alleganiensis). Two sampling protocols are described; both significantly reduced the amount of water required for collection from the previously described 6 L collection. Two-liter samples were adequate to detect hellbender presence in natural waterways where hellbenders have been previously surveyed in both Ohio and Kentucky—1 L samples were not reliable. DNA extracted from 3 L of water collected onto multiple filters (1 L/filter) could be combined and concentrated through ethanol precipitation, supporting amplification of hellbender DNA and dramatically reducing the filtration time. This method improves the efficiency and welfare implications of sampling methods for reclusive aquatic species of low population density for statewide surveys that involve collecting from multiple watersheds.
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Research
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Peer-reviewed Science
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Environmental DNA improves Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis) detection over conventional sampling methods
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Effective conservation planning relies on accurate species detection. However, conventional sampling methods used for detecting rare and cryptic aquatic species suffer from low probabilities of detection. Environmental DNA (eDNA) has emerged as an innovative and powerful sampling tool for detecting aquatic species, with previous studies suggesting a detection advantage over conventional sampling. However, comparative studies often fail to consider the appropriate sampling frameworks to adequately compare sampling methodologies and account for the influence of environmental variables on eDNA detection probabilities. In this study, we paired two detection methods (eDNA and physical sampling) at 22 sites in West Virginia, USA, to compare the probability of detecting a cryptic, elusive, and imperiled species of giant salamander, the Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis). We used a multimethod occupancy modeling framework to compare method‐specific detection probabilities using a suite of predictor variables based on environmental conditions thought to influence hellbender detection. We detected hellbenders at 19/22 sites using eDNA and at 13/22 sites using physical sampling methods. The best supported model indicated that detection probability for eDNA (0.84 ± 0.06) was three times higher than conventional methods (0.28 ± 0.07). Water turbidity was the best predictor of hellbender detection and negatively impacted our ability to detect eDNA. We failed to detect an association between eDNA concentration and hellbender catch per unit effort. Our study supports previous findings that suggest eDNA sampling methods greatly increase the probability of detecting aquatic species. However, with little known about the influence of environmental variables on eDNA detection, our results highlight the negative influence turbidity and other physiochemical factors have on eDNA detection and suggest that further research on eDNA detection in turbid environments is needed.
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Peer-reviewed Science
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FOREST REMOVAL AND THE CASCADE OF EFFECTS CORRESPONDING WITH AN OZARK HELLBENDER POPULATION DECLINE
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Populations of the endangered Ozark Hellbender salamander (Cryptobranchus alleganiensis bishopi) in the North Fork of the White River (NFWR) in Missouri and other streams have declined precipitously in recent decades. Deforestation of the riparian and nearby upland habitat has corresponded with in-river habitat changes and other interacting stressors that coincide chronologically with the precipitous decline. We review the cascade of effects, including changes in water quality, benthic habitat, illegal and scientific harvesting, and introduced and reintroduced species occurrence that followed deforestation in the context of their impacts on hellbenders and relationship with other stressors such as climate change. In-river habitat changes since the 1960s include benthic microhabitat alterations associated with redistribution of gravel, siltation, and sedimentation and, in part, increases in nuisance vegetation, including periphyton. Deforestation of riparian and nearby upland habitats increased access and opportunities for human activities such as recreation, wildlife collection, and development. The subsequent degradation of stream habitat and water quality following deforestation reducedthe carrying capacity for the NFWR Ozark Hellbender population and had negative consequences on population health.
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Peer-reviewed Science
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Movement and Habitat Use of Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis) Following Population Augmentation
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With amphibian declines at crisis levels, translocations, including population augmentations, are commonly used for amphibian conservation. Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis) have declined to low densities in many areas of their range, making them ideal candidates for population augmentation. Both wild adults and captive-reared juveniles have been used for augmentations, but their suitability has never been directly compared. Herein, we use radio telemetry with Eastern Hellbenders to examine patterns of site fidelity, movement, and habitat use over a 2-yr period for adult residents, wild adult translocates, and captive-reared juvenile translocates. We used generalized linear models and generalized linear mixed models to identify temporal trends and explore the effects of residential status (resident vs. translocate) and origin/age (captive-reared juveniles vs. wild adults) on various ecological and behavioral traits relating to habitat. Site fidelity was high in adult residents and wild adult translocates, but lower in captive-reared juvenile translocates. Both adult and juvenile translocates had greater mean movement distances than residents, leading to larger home range sizes, but these differences decreased over time. Wild adult translocates had a higher probability of using artificial nest rocks than adult residents or captive-reared juvenile translocates. This pattern was most prevalent early in the study, indicating these shelters are particularly useful during the transition to release sites. Captive-reared juvenile translocates had lower site fidelity and utilized suboptimal habitat (smaller and fewer shelter rocks) compared to wild adults. Compared to previous studies, translocations had fewer negative effects on site residents or wild translocates and might be effective at promoting growth of Hellbender populations. However, translocations of captive-reared juveniles were less successful. As we are uncertain whether captive-rearing or ontogeny led to these differences, both longer head-starting times and conditioning should be explored to improve outcomes in captive-reared juvenile cohorts.
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Peer-reviewed Science
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Pathogenic Chytrid Fungus Batrachochytrium dendrobatidis, but Not B. salamandrivorans, Detected on Eastern Hellbenders
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Recent worldwide declines and extinctions of amphibian populations have been attributed to chytridiomycosis, a disease caused by the pathogenic fungus Batrachochytrium dendrobatidis (Bd). Until recently, Bd was thought to be the only Batrachochytrium species that infects amphibians; however a newly described species, Batrachochytrium salamandrivorans (Bs), is linked to die-offs in European fire salamanders (Salamandra salamandra). Little is known about the distribution, host range, or origin of Bs. In this study, we surveyed populations of an aquatic salamander that is declining in the United States, the eastern hellbender (Cryptobranchus alleganiensis alleganiensis), for the presence of Bs and Bd. Skin swabs were collected from a total of 91 individuals in New York, Pennsylvania, Ohio, and Virginia, and tested for both pathogens using duplex qPCR. Bs was not detected in any samples, suggesting it was not present in these hellbender populations (0% prevalence, 95% confidence intervals of 0.0–0.04). Bd was found on 22 hellbenders (24% prevalence, 95% confidence intervals of 0.16 ≤ 0.24 ≤ 0.34), representing all four states. All positive samples had low loads of Bd zoospores (12.7 ± 4.9 S.E.M. genome equivalents) compared to other Bd susceptible species. More research is needed to determine the impact of Batrachochytrium infection on hellbender fitness and population viability. In particular, understanding how hellbenders limit Bd infection intensity in an aquatic environment may yield important insights for amphibian conservation. This study is among the first to evaluate the distribution of Bs in the United States, and is consistent with another, which failed to detect Bs in the U.S. Knowledge about the distribution, host-range, and origin of Bs may help control the spread of this pathogen, especially to regions of high salamander diversity, such as the eastern United States.
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