Temperature alone does not explain patterns of Batrachochytrium dendrobatidis infections in the green frog Lithobates...

Batrachochytrium dendrobatidis (Bd) is an invasive, waterborne fungal pathogen that has caused significant declines and extinctions of amphibian species worldwide. Temperature is a major factor impacting the growth and spread of Bd, but little is known regarding the associated patterns in natural habitats. This study analyzed the temperature-associated trends, as correlated with season and microhabitat, of Bd prevalence and infection intensity in green frogs Lithobates clamitans in a temperate environment (central Ohio, USA). Bd was widely distributed at the study sites and found in more than half of the frogs sampled. Bd prevalence was significantly higher in the spring and in forested stream habitats compared to emergent wetland habitats. In contrast, Bd infection intensities tended to be higher in summer. Given the known temperature sensitivity of Bd as demonstrated in laboratory studies, these findings suggest that temperature may be an important factor determining Bd prevalence in green frogs at our study sites, but that factors other than temperature are more important in determining infection intensity. Our findings suggest that future monitoring of Bd among vulnerable species in regions experiencing seasonal temperature variation should study a range of environmental variables to better understand the dynamic relationship between Bd and its amphibian hosts.