Conservation risk of Batrachochytrium salamandrivorans to endemic lungless salamanders

Abstract

The emerging fungal pathogen, Batrachochytrium salamandrivorans (Bsal), is a significant conservation threat to salamander biodiversity in Europe, although its potential to affect North American species is poorly understood. We tested the susceptibility of two genera (Eurycea and Pseudotriton) and three populations of lungless salamanders (Plethodontidae) to Bsal. All species became infected with Bsal and two (Pseudotriton ruber and Eurycea wilderae) developed chytridiomycosis. We also documented that susceptibility of E. wilderae differed among populations. Regardless of susceptibility, all species reduced feeding when exposed to Bsal at the highest zoospore dose, and P. ruber and one population of E. wilderae used cover objects less. Our results indicate that Bsal invasion in eastern North America could have significant negative impacts on endemic lungless salamander populations. Future conservation efforts should include surveillance for Bsal in the wild and in captivity, and championing legislation that requires and subsidizes pathogen‐free trade of amphibians.

Host density and habitat structure influence host contact rates and Batrachochytrium salamandrivorans transmission

“…The distribution of eastern newts overlaps with some of the highest salamander species richness in North America, and encompasses a global hotspot for Plethodontidae (lungless salamander) diversity. There is growing evidence that several species of lungless salamanders are susceptible to Bsal infection and chytridiomycosis 66 . Future research needs to include multiple species interactions and estimate community-level R 0 under different management scenarios 57 .…”

Incapacitating effects of fungal coinfection in a novel pathogen system

“…This significant keratin upregulation in coinfection could disrupt cutaneous function to an even greater degree, and warrants further testing. If similar responses are active in other susceptible salamander taxa, such as lungless plethodontids (Carter et al, 2019;Ossiboff et al, 2019), which rely heavily on cutaneous respiration and osmoregulation, coinfection could have particularly negative consequences on host survival.…”

Experimental methodologies can affect pathogenicity of Batrachochytrium salamandrivorans infections

“…Lastly, we recommend that the standardized swabbing protocol for Bd is followed [18]; however, swabbing frequency should depend on the study objectives. For studies where tracking infection dynamics is essential, swabbing once per week should capture changes in prevalence and loads given that the Bsal infected animals typically survive for several weeks [9,10], allowing for load comparisons over time. However, swabbing can affect histological interpretation of disease progression by removing skin layers (DLM, person.…”

“…Controlled experiments where hosts are exposed to Bsal under standardized conditions suggest that the pathogen has a broad host range, including several salamander and anuran families [4,9]. A central tenet to understanding Bsal invasion threat is estimating host susceptibility to infection, and whether host infection progresses to clinical disease hence its pathogenicity [10].…”