Abstract for presentation at Biodiversity Extinction Crisis Conference - A Pacific Response

Prevention of amphibian mass extinction

  • A/Prof Russell Poulter, University of Otago, Dunedin, New Zealand
  • Prof Rick Speare, James Cook University, Townsville, Australia
  • Dr Phil Bishop, University of Otago, Dunedin, New Zealand
  • Dr Margi Butler, University of Otago, Dunedin, New Zealand

    • A third of all amphibian species are threatened with extinction; 122 species have disappeared since 1980. The threat is partly due to a pathogenic chytrid fungus, Batrachochytrium dendrobatidis. First identified six years ago, B. dendrobatidis is well established in parts of the Americas, Australia and Europe. In 2001 B. dendrobatidis was discovered during a dramatic decline of a New Zealand native frog (Leiopelma archeyi) a species is listed as Nationally Critical by the Department of Conservation, New Zealand. The genus Leiopelma is an ancient and primitive group of frog.
    There is no described method to stop the spread of the chytrid, nor to treat wild amphibian populations that are infected. Captive breeding programmes are planned to preserve threatened species until the chytrid can be beaten. However, the ubiquity of the chytrid makes captive breeding programmes difficult and many species cannot be bred in captivity.
    Chytrids are an unusual, ancient kingdom of fungi (Chytridomycota), quite unlike the more familiar yeasts and moulds. Chytrids are not well defined in terms of sensitivity to antibiotics, including the antifungals used against other pathogenic fungi. We have performed an extensive screen of antibiotics and antifungals for activity against B. dendrobatidis in vitro. We have developed a potentially useful protocol that is lethal to chytrids in vitro (after 5 days) and completely non-toxic to amphibians. We have shown (using PCR) that this protocol cures experimentally infected Litoria ewingi (Brown Tree frog) and L. raniformis (Southern Bell frog, IUCN status is endangered). The protocol is also effective for naturally infected Leiopelma archeyi. The protocol is effective against chytrids infecting adults and tadpoles. This protocol will provide an invaluable tool for captive breeding and/or relocation programmes including those involving critically endangered New Zealand frogs. The protocol can, in principle, be modified for use in environmental remediation.

    Conference Organiser - ICMS Pty Ltd