Pathogenic Chytrid Fungus Batrachochytrium dendrobatidis, but Not B. salamandrivorans, Detected on Eastern Hellbenders

Abstract

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.

Widespread occurrence of an emerging fungal pathogen in heavily traded Chinese urodelan species

“…The chytrid fungus Batrachochytrium salamandrivorans (Bsal) recently invaded northwestern Europe (Martel et al., ), causing extinction events in urodelan populations (Stegen et al., ) and threatening the majority of urodelan diversity in the western Palearctic (Martel et al., ). Current evidence suggests Bsal is probably absent from the highly urodelan diverse regions in Northern and Latin America (Bales et al., ; Martel et al., ). In Asia, Bsal appears to coexist with native urodelan communities in Vietnam (Laking et al.…”

Averting a North American biodiversity crisis

“…North America is the world's salamander biodiversity hotspot with 48% of 676 recognized salamander species representing 9 of the 10 known families within the order Caudata (190 species in the United States, 137 in Mexico, and 21 in Canada) ( 8). Bsal has not been reported in North America, although few studies have been published in the short time since Bsal was described ( 9,10).…”

Experimentally Induced Metamorphosis in Axolotl (Ambystoma mexicanum) Under Constant Diet Restructures Microbiota Accompanied by Reduced Limb Regenerative Capacity

“…Future experiments should also include eukaryotic microbiota since fungal skin infections (e.g. chytridiomycosis) in amphibians adversely affects the vital function of amphibian skin 45,46 .…”