The chytrid fungusBatrachochytrium dendrobatidisis non‐randomly distributed across amphibian breeding habitats

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Abstract
The chytrid fungusBatrachochytrium dendrobatidishas been implicated as the causative agent of mass mortalities, population declines, and the extinctions of stream‐breeding amphibian species worldwide. While the factors that limit the distribution and abundance ofB. dendrobatidisacross large geographical regions are fairly well understood, little is known about the distribution of the fungus within localized areas such as individual catchments. The accurate identification of amphibian populations likely to be exposed to the fungus is urgently required for effective disease management. We conducted disease surveys of frogs representing five ecological guilds in south‐east Queensland, Australia, and hypothesized that ifB. dendrobatidiswere responsible for the disappearance of stream‐breeding amphibian populations, infection prevalence and intensity would be greatest in frogs breeding in permanent, flowing water. Overall, 30.3% of the 519 frogs we sampled were infected withB. dendrobatidis. However, infections were not evenly distributed across the ecological guilds, being almost completely restricted to frogs breeding at permanent waterbodies. Of these, stream breeders were significantly more likely to be infected than were pond breeders, though the intensity of frogs’ infections did not differ significantly between the two guilds.Batrachochytrium dendrobatidiswas detected on only one of the 117 frogs that were found at ephemeral ponds, ephemeral streams, or terrestrial sites. These findings provide strong support for the hypothesis thatB. dendrobatidiswas responsible for many of the unexplained disappearances of stream‐breeding amphibian populations in recent decades, and will enable wildlife managers to more accurately focus conservation efforts on those species at highest risk of disease‐related decline.