Indirect effects of invasive species removal devastate World Heritage Island

Authors

  • Dana M. Bergstrom,

    Corresponding author
    1. Australian Antarctic Division, Department of the Environment, Water, Heritage and the Arts, 203 Channel Highway, Kingston 7050, Australia;
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  • Arko Lucieer,

    1. School of Geography and Environmental Studies, University of Tasmania, Private Bag 76, Hobart 7001, Tasmania, Australia;
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  • Kate Kiefer,

    1. Australian Antarctic Division, Department of the Environment, Water, Heritage and the Arts, 203 Channel Highway, Kingston 7050, Australia;
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  • Jane Wasley,

    1. Australian Antarctic Division, Department of the Environment, Water, Heritage and the Arts, 203 Channel Highway, Kingston 7050, Australia;
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  • Lee Belbin,

    1. Blatant Fabrications Pty Ltd, Hobart, Tasmania, Australia; and
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  • Tore K. Pedersen,

    1. Australian Antarctic Division, Department of the Environment, Water, Heritage and the Arts, 203 Channel Highway, Kingston 7050, Australia;
    2. School of Geography and Environmental Studies, University of Tasmania, Private Bag 76, Hobart 7001, Tasmania, Australia;
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  • Steven L. Chown

    1. Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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*Correspondence author. E-mail: dana.bergstrom@aad.gov.au

Summary

  • 1Owing to the detrimental impacts of invasive alien species, their control is often a priority for conservation management. Whereas the potential for unforeseen consequences of management is recognized, their associated complexity and costs are less widely appreciated.
  • 2We demonstrate that theoretically plausible trophic cascades associated with invasive species removal not only take place in reality, but can also result in rapid and drastic landscape-wide changes to ecosystems.
  • 3Using a combination of population data from of an invasive herbivore, plot-scale vegetation analyses, and satellite imagery, we show how a management intervention to eradicate a mesopredator has inadvertently and rapidly precipitated landscape-wide change on sub-Antarctic Macquarie Island. This happened despite the eradication being positioned within an integrated pest management framework. Following eradication of cats Felis catus in 2001, rabbit Oryctolagus cuniculus numbers increased substantially although a control action was in place (Myxoma virus), resulting in island-wide ecosystem effects.
  • 4Synthesis and applications. Our results highlight an important lesson for conservation agencies working to eradicate invasive species globally; that is, risk assessment of management interventions must explicitly consider and plan for their indirect effects, or face substantial subsequent costs. On Macquarie Island, the cost of further conservation action will exceed AU$24 million.

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