Are alien fish disadvantaged by extremely variable flow regimes in arid-zone rivers?
J. F. Costelloe A H , J. R. W. Reid B C D , J. C. Pritchard C E , J. T. Puckridge C , V. E. Bailey F and P. J. Hudson C GA Department of Civil and Environmental Engineering, University of Melbourne, Vic. 3010, Australia.
B CSIRO Sustainable Ecosystems, GPO Box 284, Canberra, ACT 2601, Australia.
C School of Earth and Environmental Sciences, The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia.
D Present address: The Fenner School of Environment and Society, Australian National University, Acton, ACT 0200, Australia.
E Present address: Murray Darling Basin Authority, 51 Allara St, Canberra, ACT 2601, Australia.
F Environmental Protection Agency, PO Box 202, Longreach, Qld 4730, Australia.
G Present address: South Australian Museum, Adelaide, SA 5000, Australia.
H Corresponding author. Email: jcost@unimelb.edu.au
Marine and Freshwater Research 61(8) 857-863 https://doi.org/10.1071/MF09090
Submitted: 16 April 2009 Accepted: 25 February 2010 Published: 13 August 2010
Abstract
The proliferation of alien fish in dryland rivers potentially obstructs the maintenance of river health. Modified flow regimes are hypothesised to facilitate invasions by alien fish but in unregulated dryland rivers, large floods provide a recruitment advantage for native over alien species whereas droughts favour alien species. We tested these hypotheses by using data from a 3-year study (2000–2003) of fish populations in the unmodified rivers of the Lake Eyre Basin (LEB) of Australia. Results from a lower reach of Cooper Creek were compared with those of an earlier study (1986–1992). During both periods, large floods occurred, with return periods ranging from >1 in 5 to >1 in 25 years. In the lower Cooper, decreases in the abundance of alien species relative to native species, and dramatic increases in recruitment of native species, were observed during a 1–3-year period following large floods. In two other rivers in 2000–2003, there was no statistically significant change in the already low abundances of alien species. We suggest that the naturally variable hydrological regimes and native-dominant fish assemblages of the unregulated LEB rivers afford some resistance to the establishment and proliferation of alien fish through flood and drought conditions.
Additional keywords: arid zone, Cooper Creek, Diamantina River, dryland rivers, flow variability, habitat, Neales River, recruitment.
Acknowledgements
Funding for the ARIDFLO project was provided by the Natural Heritage Trust for the Environmental Flows Program, an initiative of Environment Australia. The project was administered through the South Australian Department of Water, Land and Biodiversity Conservation and the University of Adelaide. We particularly acknowledge the project manager, Michael Good. Local landholders are thanked for access to their properties during fieldwork. The fieldwork also relied on a large number of selfless volunteers. The constructive comments of three journal reviewers, the associate editor and the editor have greatly improved this paper, and are sincerely appreciated. We dedicate this work to the late Dr Jim Puckridge, who instigated and led the ARIDFLO project.
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