Reservoir-host amplification of disease impact in an endangered amphibian

Scheele, Ben C., Hunter, David A., Brannelly, Laura A., Skerratt, Lee F., and Driscoll, Don A. (2017) Reservoir-host amplification of disease impact in an endangered amphibian. Conservation Biology, 31 (3). pp. 592-600.

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Emerging wildlife pathogens are an increasing threat to biodiversity. One of the most serious wildlife diseases is chytridiomycosis, caused by the fungal pathogen, Batrachochytrium dendrobatidis (Bd), which has been documented in over 500 amphibian species. Amphibians vary greatly in their susceptibility to Bd; some species tolerate infection, whereas others experience rapid mortality. Reservoir hosts—species that carry infection while maintaining high abundance but are rarely killed by disease—can increase extinction risk in highly susceptible, sympatric species. However, whether reservoir hosts amplify Bd in declining amphibian species has not been examined. We investigated the role of reservoir hosts in the decline of the threatened northern corroboree frog (Pseudophryne pengilleyi) in an amphibian community in southeastern Australia. In the laboratory, we characterized the response of a potential reservoir host, the (nondeclining) common eastern froglet (Crinia signifera), to Bd infection. In the field, we conducted frog abundance surveys and Bd sampling for both P. pengilleyi and C. signifera. We built multinomial logistic regression models to test whether Crinia signifera and environmental factors were associated with P. pengilleyi decline. C. signifera was a reservoir host for Bd. In the laboratory, many individuals maintained intense infections (>1000 zoospore equivalents) over 12 weeks without mortality, and 79% of individuals sampled in the wild also carried infections. The presence of C. signifera at a site was strongly associated with increased Bd prevalence in sympatric P. pengilleyi. Consistent with disease amplification by a reservoir host, P. pengilleyi declined at sites with high C. signifera abundance. Our results suggest that when reservoir hosts are present, population declines of susceptible species may continue long after the initial emergence of Bd, highlighting an urgent need to assess extinction risk in remnant populations of other declined amphibian species.

Item ID: 48488
Item Type: Article (Research - C1)
ISSN: 1523-1739
Keywords: Batrachochytrium dendrobatidis, chytrid fungus, frog decline, pathogen-mediated apparent competition, vector, wildlife disease
Funders: Australian Academy of Science, Taronga Zoo (TZ), Australian Research Council (ARC)
Projects and Grants: TZ Field Conservation Grant, ARC grant LP110200240
Date Deposited: 18 Apr 2017 02:52
FoR Codes: 30 AGRICULTURAL, VETERINARY AND FOOD SCIENCES > 3009 Veterinary sciences > 300905 Veterinary epidemiology @ 100%
SEO Codes: 96 ENVIRONMENT > 9604 Control of Pests, Diseases and Exotic Species > 960405 Control of Pests, Diseases and Exotic Species at Regional or Larger Scales @ 100%
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