PS 44-107 - Studies of Batrachochytrium dendrobatidis in amphibian populations in central Ohio 2010: Seasonal patterns, taxonomic distribution, and habitat

Wednesday, August 10, 2011
Exhibit Hall 3, Austin Convention Center
Chelsea A. Korfel and Thomas E. Hetherington, Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH

Batrachochytrium dendrobatidis (Bd), the pathogenic fungus linked to the declines and extinctions of many species of amphibians worldwide, occurs in Ohio.  Bd has been found throughout the United States, but much remains to be known about its precise distribution and impact on amphibian populations.  Here, we have focused on seven nature preserves in central Ohio to collect samples March – November 2010. Our objectives were threefold: 1) to monitor the seasonal fluctuations of Bd in central Ohio, 2) to better understand the taxonomic distribution of Bd in central Ohio’s amphibian species, and 3) to examine the effects of wetland type (i.e. habitat) on Bd colonization.  We predicted that Bd colonization would fluctuate seasonally in response to the fungus’ critical temperature range (4- 28 degrees C), and we anticipated finding low levels of Bd during both the coldest and hottest months. Taxonomically, we were interested in which species are more likely to carry Bd in addition to the relative zoospore count.  Our samples were collected from 4 wetland types, and we hypothesized that the more moderate temperatures of forested pools and moving water would be more likely to host Bd. We collected 348 Bd swab samples from 14 species of amphibians. 


Overall, we found a prevalence of 15.8% Bd positive. Seasonally, we found the highest number of positive samples during the months of April (16) and August (14), the lowest number of positive samples during March (0); and that Bd persisted, surprisingly, through the summer months. Taxonomically, we found no evidence of Bd in either ambystomatid (55 tested) or plethodontid (28 tested) salamanders. The fungus was found in bufonid, hylid, and ranid anurans, and was especially prevalent in infection rate and intensity in green frogs (Lithobates clamitans, 44% positive) and American bullfrogs (L. catesbeianus, 75% positive) The presence of Bd in ranid frogs showed little correlation with season, and was observed at comparable levels in spring, summer and autumn. Bd was found in all types of wetlands studied; however, we found the highest incidence in streams and the lowest in vernal pools. This is likely a result of the species that we found in each wetland type (i.e. wood frogs (L. sylvaticus) collected in vernal pools with 0% positive; American bullfrogs collected in streams with 75% positive).  In conclusion, Bd persisted through the hottest months of the year, was particularly prevalent in ranids, and was found more commonly in stream habitats.

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