Moving forward in understanding disease of wild hellbenders

The Hellbender, Cryptobranchus alleganiensis, is a large aquatic salamander containing two subspecies (Ozark Hellbender, C. a. bishopi and Eastern Hellbender, C. a. alleganiensis) from the Ozark mountains and eastern U.S.,... [ view full abstract ]

The Hellbender, Cryptobranchus alleganiensis, is a large aquatic salamander containing two subspecies (Ozark Hellbender, C. a. bishopi and Eastern Hellbender, C. a. alleganiensis) from the Ozark mountains and eastern U.S., respectively. Both subspecies have seen population declines over the past 25 years, especially in C. a. bishopi which is federally endangered. Habitat degradation and possibly low genetic diversity may lead to secondary infections with amphibian pathogens such as Ranavirus and Batrachochytrium dendrobatidis (Bd). Other pathogens such as the emerging salamander chytrid (Batrachochytrium salamandrivorans or Bsal) and other bacterial or fungal species are also of concern as either primary or secondary causes of disease. Our objective is to determine prevalence of these pathogens in both subspecies to understand the role of emerging amphibian pathogens in C. alleganiensis declines. We collected tail tissue and skin swabs from C. a. bishopi and C. a. alleganiensis individuals from Arkansas and Tennessee respectively during the summers of 2011-2014. We used qPCR analysis to determine presence of Ranavirus and Bd from tail samples and skin swabs, respectively. In the latter two years we collected swabs for metagenomic analyses of active lesions. Overall, for C. a. bishopi, we detected 27% prevalence of Bd and no cases of ranaviral infections; for C. a. alleganiensis, we detected 15% prevalence of Bd and 3% prevalence of Ranavirus. We have not found any Bsal positive individuals. These data reveal that Bd is present in these populations. We are currently in our second phase of investigating morbidity and mortality in hellbenders. We are incorporating metagenomic comparisons of lesions and healthy skin, bacterial peptide production, and classification of chytrid strains potentially unique to wild hellbender populations.