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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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Peer-reviewed Science
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The use of nest boxes by the hellbender salamander in Western North Carolina
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The hellbender salamander (Cryptobranchus alleganiensis) is a unique, large-bodied amphibian that serves as an excellent water quality indicator species in Western North Carolina. This animal has suffered substantial population declines over the past four decades throughout its range. Increased stream siltation largely attributed to human development fills the concave undersides of large rocks, consequently destroying hellbender breeding habitat. Habitat degradation has contributed to reductions in North Carolinian populations to such a degree that the species is now considered of Special Concern in the state. In order to restore hellbender population sizes under current land use conditions, researchers have recently begun developing artificial nest boxes that exclude sediment and promote increased reproduction. To identify the short-term efficacy of these shelters as substitutes for natural hellbender habitat in Western North Carolina, I constructed and placed 54 boxes across five river sites throughout the region. Following summer nest box installment, I examined each shelter through the breeding season for hellbender in habitation and to determine the quality of water passing through the structures. Additionally, I created a maximum entropy species distribution model and conducted a spatial connectivity analysis for the hellbenders of Western North Carolina to identify ideal locations for nest boxes installation in the future. Although no hellbenders have yet been detected in the artificial shelters, additional structural improvements and time may reveal nest boxes to be useful conservation tools for this iconic species of Special Concern.
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Artificial Nest Box Research
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Theory and practice of the hydrodynamic redesign of artifical hellbender habitat
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The success of nest boxes in Missouri led researchers to test whether similar management tools could increase C. a. alleganiensis populations in the streams of western North Carolina, where these salamanders are listed as a Species of Special Concern (Messerman 2014). Fifty-four nest boxes were constructed following the boot-shaped design of Briggler and Ackerson (2012) in May 2013, and were installed across five known C. alleganiensis stream sites between late June and early August 2013. Messerman (2014) then monitored each nest box every three to four weeks through November 2013, and the boxes were revisited in August 2014 and July 2015 to observe structural condition and occupancy (Messerman, pers. obs.). Of the 54 nest boxes, only two structures at a single site were confirmed as inhabited in 2014 and 2015, and no breeding events were detected (Messerman, pers. obs.). Moreover, many of these ~50 lb concrete boxes moved in flood events or accumulated sediment at the downstream tunnel entrance (Messerman 2014). The low success of the boot-shaped nest box design in North Carolina may be attributed to the sites generally being narrower and shallower than those in Missouri, with much of the substrate consisting of bedrock slabs covered by relatively thin layers of rock, gravel and silt. Here we address the observed shortcomings of the original North Carolina design through the lens of engineering, and present a new and easily implemented nest box model for use in streams like those found in western North Carolina.
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Artificial Nest Box Research
