Terrestrial Dispersal and Potential Environmental Transmission of the Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis).

Jacob Lawrence Kerby,Jonathan E. Kolby,Kathryn L. Richards-Hrdlicka,Merlijn Jocque,Lee Berger,Lee F. Skerratt,Sara D. Ramirez

doi:10.1371/journal.pone.0125386

Abstract

Dispersal and exposure to amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) is not confined to the aquatic habitat, but little is known about pathways that facilitate exposure to wild terrestrial amphibians that do not typically enter bodies of water. We explored the possible spread of Bd from an aquatic reservoir to terrestrial substrates by the emergence of recently metamorphosed infected amphibians and potential deposition of Bd-positive residue on riparian vegetation in Cusuco National Park, Honduras (CNP). Amphibians and their respective leaf perches were both sampled for Bd presence and the pathogen was detected on 76.1% (35/46) of leaves where a Bd-positive frog had rested. Although the viability of Bd detected on these leaves cannot be discerned from our quantitative PCR results, the cool air temperature, closed canopy, and high humidity of this cloud forest environment in CNP is expected to encourage pathogen persistence. High prevalence of infection (88.5%) detected in the recently metamorphosed amphibians and frequent shedding of Bd-positive residue on foliage demonstrates a pathway of Bd dispersal between aquatic and terrestrial habitats. This pathway provides the opportunity for environmental transmission of Bd among and between amphibian species without direct physical contact or exposure to an aquatic habitat.

Highlights

Infection by the pathogenic amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) poses a major threat to global amphibian biodiversity [1,2]
Post-metamorphic anurans, in particular, often exhibit both elevated Bd prevalence and zoospore loads [24,37,38,39], so their emergence from water might represent a considerable pathway of Bd dispersal into the terrestrial zone. To explore this potential avenue of terrestrial Bd spread we investigated whether terrestrial vegetation becomes contaminated with Bd following contact with recently metamorphosed amphibians under natural field conditions
Permission to export samples was granted by Honduran permit #'s 44735 and 19987. This investigation was performed from 9 July to 6 August 2013 in Cusuco National Park (CNP), a montane rainforest located in the Sierra de Omoa of northwestern Honduras

Summary

Introduction

Infection by the pathogenic amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) poses a major threat to global amphibian biodiversity [1,2]. This does not alter the authors' adherence to PLOS ONE policies on sharing data and materials. Bd demonstrates low host species specificity and as of 2012, infection had already been reported in 516 species from 52 countries [9], and evidence suggests this pathogen is native in some parts of its range but emerging and spreading in others [10,11]. Mechanisms of dispersal outside the amphibian host and in the absence of anthropogenic assistance are more obscure

Methods

Results

Conclusion