DAO prepress abstract  -  doi: 10.3354/dao01923

ABSTRACT: Spread of the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) has caused the decline and extinction of frogs, but the distribution of Bd is incompletely known. This information is crucial to implementing appropriate quarantine strategies, preparing for outbreaks of chytridiomycosis due to introduction of Bd, and for directing conservation actions towards affected species.  This protocol provides a simple and standard method for sampling all frog populations in Australia to maximise the chances of detecting Bd. In order to structure and prioritise the survey protocol, areas are divided by bioregion and frog species are allocated depending on the water bodies they utilize into three groups that represent different levels of risk of exposure to Bd.  Sixty individuals per population need to be tested to be 95 % certain of detecting one positive frog based on the minimum apparent prevalence of ≥5 % in infected Australian frog populations and using a quantitative real time Taqman polymerase chain reaction test.  The appropriate season to sample varies between bioregions and will ideally incorporate temperatures favourable for chytridiomycosis (eg. maximum air temperatures generally <27°C). Opportunistic collection and testing of sick frogs and tadpoles with abnormal mouthparts should also be done to increase the probability of detecting Bd.  The survey priorities in order are: threatened species that may have been exposed to Bd, bioregions surrounding infected bioregions and ecological groups and then species of frogs of unknown infection status in infected bioregions. Within these priorities sampling should first target: ecological groups and species such as those associated with permanent water that are likely to be exposed to Bd and areas within bioregions that are high risk for Bd based on climatic modelling. This protocol can be adapted for use in other countries and a standard protocol will enable comparison among amphibian populations globally.