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RESEARCH ARTICLE
Contents Vol 61(3)

Dynamic stability in dry season food webs within tropical floodplain rivers

Catherine Leigh A C , Michele A. Burford A , Fran Sheldon A B and Stuart E. Bunn A
+ Author Affiliations
- Author Affiliations

A Australian Rivers Institute, Griffith University, 170 Kessels Road, Nathan, Qld 4111, Australia.

B Griffith School of Environment, Griffith University, 170 Kessels Road, Nathan, Qld 4111, Australia.

C Corresponding author. Email: c.leigh@griffith.edu.au

Marine and Freshwater Research 61(3) 357-368 https://doi.org/10.1071/MF09107
Submitted: 12 May 2009  Accepted: 7 September 2009   Published: 29 March 2010

Abstract

Debate exists about the effects of hydrological variation on food web dynamics and the relative importance of different sources of organic carbon fuelling food webs in floodplain rivers. Stable carbon isotope analyses and ecological stoichiometry were used to determine the basal sources in dry season macroinvertebrate food webs in two floodplain river systems of Australia’s wet–dry tropics that have contrasting flow regimes. Algae, associated with phytoplankton and biofilm, were the primary food source, potentially contributing >55% organic carbon to the biomass of a wide range of primary and secondary consumers. However, many consumers assimilated other sources in addition to algae, e.g. detritus from local C3 riparian vegetation. Food webs were characterised by substantial flexibility in the number and types of sources identified as important, which was indicative of generalist feeding strategies. These findings suggest ‘dynamic stability’ in the food webs, which imparts resilience against natural disturbances like flow regime seasonality and variation in hydrological connectivity. This adaptation may be characteristic of macroinvertebrate assemblages in highly seasonal river systems or in those with high levels of flow variability.

Additional keywords: algae, carbon : nitrogen, Gulf of Carpentaria, hydrological connectivity, macroinvertebrates, terrestrial detritus.


Acknowledgements

Research funding was provided by Land & Water Australia (Project code GRU35) with additional support from the Griffith School of Environment and Australian Rivers Institute. We thank colleagues at the Australian Rivers Institute for comments on manuscript drafts and advice on field and laboratory methods and preparation. We thank local indigenous communities, pastoral leaseholders and station managers for granting permission and access to field sites, and Erica Alacs, Ben Cook, James Fawcett, Joel Huey, Jim McGuire, Tim Page, Terry Reis, Brett Taylor and Matthew Vickers (Southern Gulf Catchments) for assistance in the field. Macroinvertebrates collected in 2005 were identified by Dardanus Scientific, Hawthorne, Australia. We thank Andrew Boulton, David Dudgeon and an anonymous reviewer for their comments on our manuscript.


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