The Eastern hellbender and Batrachochytrium dendrobatidis (Bd) in western New York

In 2009, a five-year captive rear-and-release program of eastern hellbenders was initiated to bolster the wild population in the Allegany River in southwest New York State. Adult hellbenders were released into the streams with... [ view full abstract ]

In 2009, a five-year captive rear-and-release program of eastern hellbenders was initiated to bolster the wild population in the Allegany River in southwest New York State. Adult hellbenders were released into the streams with a survival rate of 4-8%. Sources of mortality included Batrachochytrium dendrobatidis (Bd) infection, predation, poor adaptation, and environmental toxins. In 2014, a soft release of 25 hellbenders was performed to determine causes of mortality and track Bd infections in individuals over the course of five months. These animals were sourced from two populations: Buffalo Zoo (n=21) and the Seneca Nation Indians (n=4), releases occurred between June and September with regular monitoring until November. Hellbenders were swabbed for Bd, weighed, observed, and photographed each time they were checked. Bd loads were quantified using a real time PCR assay. Monitoring occurred for 19 weeks, during which 76% of study animals died. Most mortalities occurred four to eight weeks post-release. Eight animals were recovered for necropsy; seven of which showed clinical signs of chytridiomycosis with no other underlying causes of death. Over the course of the study, 22 hellbenders tested positive for Bd with levels ranging from 3.68x104 to 1.40x108 ITS-1 copies. Out of the 19 hellbender mortalities, all were from the Buffalo Zoo; and these animals had higher Bd levels at four weeks after release compared to Seneca Nation animals. Bd appears to affect survival of naïve animals after release in the Allegany watershed. Further investigation revealed that the Seneca Nation facility had been infected with Bd sometime between 2010 and 2014, which may have exposed animals to Bd prior to release and provided protection against lethal infections. Our next steps are to bolster hellbenders’ immune system against Bd in order to increase survival upon release.