Whitfield Et Al 2012

BIOTROPICA 0(0): 1–6 2012

10.1111/j.1744-7429.2012.00872.x

Temporal Variation in Infection Prevalence by the Amphibian Chytrid Fungus in Three
Species of Frogs at La Selva, Costa Rica
Steven M. Whitfield2,4, Jacob Kerby2, Lydia R. Gentry3, and Maureen A. Donnelly1
1

Department of Biological Sciences, Florida International University, UP Campus, OE 167, Miami, Florida, U.S.A.

2

Biology Department, University of South Dakota, Vermillion, South Dakota, U.S.A.

3

College of Veterinary Medicine, Washington State University, Pullman, Washington, U.S.A.

ABSTRACT
The emerging infectious disease chytridiomycosis, caused by the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), is implicated in widespread population declines, extirpations, and extinctions of amphibians throughout the world. In the Neotropics, most amphibian declines have occurred in cool mid- to high-elevation sites (> 400 m asl), and it is hypothesized that high temperatures limit the growth of Bd in lowland tropical sites, despite few data available on the distribution of Bd in lowland forests. Here, we report the results of a
12-mo pathogen surveillance program for three common species of frogs at a warm lowland site in northeastern Costa Rica. We combine standard non-invasive skin swabbing techniques with a quantitative polymerase chain reaction assay to analyze the infection prevalence and Bd load across a 1-yr period. Our data indicate an overall Bd infection rate of 6.1 percent, but prevalence varies from < 5 percent in warmer months to a peak of 34.7 percent in the coolest months of the year. Despite very little seasonal variation in temperature (< 4°C), our data indicate strong seasonal variation in the prevalence of Bd, with highest prevalence of infection in months with coolest air temperatures. While it has been suggested that Bd is primarily a riparian fungus, we find no difference in prevalence of infection among our species despite considerable differences in affiliation of

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