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Experimental exposure indicates the amphibian chytrid pathogen poses low risk to New Zealand's threatened endemic frogs

Authors

  • M. E. Ohmer,

    Corresponding authorCurrent affiliation:
    1. School of Biological Sciences, The University of Queensland, Brisbane, QLD, Australia
    • Department of Zoology, University of Otago, Dunedin, New Zealand
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  • S. M. Herbert,

    1. Department of Zoology, University of Otago, Dunedin, New Zealand
    Current affiliation:
    1. Tropical Health Solutions Pty Ltd, New Plymouth, New Zealand
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  • R. Speare,

    1. Anton Breinl Centre for Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Townsville, QLD, Australia
    Current affiliation:
    1. EcoGecko Consultants Ltd, Townsville, QLD, Australia
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  • P. J. Bishop

    1. Department of Zoology, University of Otago, Dunedin, New Zealand
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  • Editor: Trent Garner

Correspondence

Email: m.e.ohmer@gmail.com

Abstract

The spread of chytridiomycosis, an emerging infectious disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is one of many threats facing amphibians worldwide. Ascertaining the severity of this threat to particular amphibian species is necessary if managers are to prioritize conservation actions. In New Zealand, Bd has been detected on both threatened endemic (Leiopelma spp.) and widespread introduced (Litoria spp.) anuran species, but Le. archeyi, one of four native species, has demonstrated low susceptibility to chytridiomycosis in captivity. To determine potential impacts of Bd on New Zealand's native anuran fauna, we assessed the susceptibility of two native species, Le. pakeka and Le. hochstetteri, to chytridiomycosis. We exposed Bd-naïve individuals to a virulent New Zealand isolate of Bd, and monitored infection status with quantitative real-time polymerase chain reaction. Both species demonstrated low susceptibility and all individuals cleared Bd infection (Le. hochstetteri by week 10, Le. pakeka by week 15). Furthermore, no frogs demonstrated clinical signs of chytridiomycosis. Since Le. archeyi has similarly demonstrated low susceptibility, this appears to be a genus-wide trend, which warrants further study of the mechanism of this response. These findings, in agreement with results from field surveys and analyses of skin peptide defenses, suggest that Bd poses a low risk to leiopelmatids. An investigative study of potential susceptibility to Bd, such as this one, can better equip managers to target imminent threats and focus conservation plans for at-risk amphibian fauna.

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