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Hydrological disturbance benefits a native fish at the expense of an exotic fish

  1. F. LEPRIEUR1,
  2. M. A. HICKEY2,
  3. C. J. ARBUCKLE3,
  4. G. P. CLOSS4,
  5. S. BROSSE1,
  6. C. R. TOWNSEND4

Article first published online: 23 AUG 2006

DOI: 10.1111/j.1365-2664.2006.01201.x

Issue

Journal of Applied Ecology

Journal of Applied Ecology

Volume 43, Issue 5, pages 930–939, October 2006

Additional Information

How to Cite

LEPRIEUR, F., HICKEY, M. A., ARBUCKLE, C. J., CLOSS, G. P., BROSSE, S. and TOWNSEND, C. R. (2006), Hydrological disturbance benefits a native fish at the expense of an exotic fish. Journal of Applied Ecology, 43: 930–939. doi: 10.1111/j.1365-2664.2006.01201.x

Author Information

  1. 1

    Laboratoire Dynamique de la Biodiversité, UMR 5172, CNRS – Université Paul Sabatier, 118 route de Narbonne, F-31062 Toulouse cedex 4, France;

  2. 2

    Otago Regional Council, 70 Stafford Street, Dunedin, New Zealand;

  3. 3

    Environment Southland, Private Bag 90116, Invercargill, Southland, New Zealand; and

  4. 4

    Department of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand

* Fabien Leprieur, Laboratoire Dynamique de la Biodiversité, UMR 5172, CNRS – Université Paul Sabatier, 118 route de Narbonne, F-31062 Toulouse cedex 4, France (e-mail leprieur@cict.fr).

Publication History

  1. Issue published online: 23 AUG 2006
  2. Article first published online: 23 AUG 2006
  3. Received 19 July 2005; final copy received 13 April 2006Editor: Paul Giller

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Keywords:

  • biological invasion;
  • disjunct distributions;
  • disturbance;
  • galaxiids;
  • introduced trout;
  • water abstraction

Summary

  • 1
    Some native fish in New Zealand do not coexist with introduced salmonids. Previous studies of disjunct distributions of exotic brown trout Salmo trutta and native galaxiids demonstrated native extirpation except where major waterfalls prevented upstream migration of trout. In the Manuherikia River system, we predicted that water abstraction might be a further factor controlling the spatial distribution of both the invader and a native fish.
  • 2
    We applied multiple discriminant function analyses to test for differences in environmental conditions (catchment and instream scales) at sites with roundhead galaxias Galaxias anomalus and brown trout in sympatry and allopatry. We then used a supervised artificial neural network (ANN) to predict the presence–absence of G. anomalus and brown trout (135 sites). The quantification of contributions of environmental variables to ANN models allowed us to identify factors controlling their spatial distribution.
  • 3
    Brown trout can reach most locations in the Manuherikia catchment, and often occur upstream of G. anomalus. Their largely disjunct distributions in this river are mediated by water abstraction for irrigation, together with pool habitat availability and valley slope. Trout are more susceptible than the native fish to stresses associated with low flows, and seem to be prevented from eliminating galaxiid populations from sites in low gradient streams where there is a high level of water abstraction.
  • 4
    Synthesis and applications. In contrast to many reports in the literature, our results show that hydrological disturbance associated with human activities benefits a native fish at the expense of an exotic in the Manuherikia River, New Zealand. Water abstraction is also known to have negative impacts on native galaxiids, therefore we recommend restoring natural low flows to maintain sustainable habitats for native galaxiids, implementing artificial barriers in selected tributaries to limit trout predation on native fish, and removing trout upstream.
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