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RESEARCH ARTICLE
Contents Vol 61(4)

Trophic structure of benthic resources and consumers varies across a regulated floodplain wetland

Jeff Kelleway A , Debashish Mazumder B , G. Glenn Wilson C , Neil Saintilan A , Lisa Knowles A , Jordan Iles A and Tsuyoshi Kobayashi A D
+ Author Affiliations
- Author Affiliations

A NSW Department of Environment, Climate Change and Water, PO Box A290, Sydney South, NSW 1232, Australia.

B Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia.

C School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia.

D Corresponding author. Email: Yoshi.Kobayashi@environment.nsw.gov.au

Marine and Freshwater Research 61(4) 430-440 https://doi.org/10.1071/MF09113
Submitted: 19 May 2009  Accepted: 12 September 2009   Published: 27 April 2010

Abstract

Riverine food webs are often laterally disconnected (i.e. between watercourses) in regulated floodplain wetlands for prolonged periods. We compared the trophic structure of benthic resources and consumers (crustaceans and fish) of the three watercourses in a regulated floodplain wetland (the Gwydir Wetlands, Australia) that shared the same source water but were laterally disconnected. The crustaceans Cherax destructor (yabby), Macrobrachium australiense (freshwater prawn), the exotic fish Cyprinus carpio (European carp) and Carassius auratus (goldfish) showed significantly different δ13C values among the watercourses, suggesting spatial differences in primary carbon sources. Trophic positions were estimated by using δ15N values of benthic organic matter as the base of the food web in each watercourse. The estimated trophic positions and gut contents showed differences in trophic positions and feeding behaviours of consumers between watercourses, in particular for Melanotaenia fluviatilis (Murray–Darling rainbowfish) and M. australiense. Our findings suggest that the observed spatial variation in trophic structure appears to be largely related to the spatial differences in the extent and type of riparian vegetation (i.e. allochthonous carbon source) across the floodplain that most likely constituted part of the benthic resources.

Additional keywords: allochthonous carbon source, food webs, riparian vegetation, river regulation, spatial segregation, stable isotopes.


Acknowledgements

Funding for this research was provided by the Australian Government through the Cotton Catchment Communities CRC and the NSW Wetland Recovery Program which is jointly funded by the NSW Government and the Australian Government's Water for the Future-Water Smart Australia Program. Fish sampling was carried out in accordance with NSW Department of Primary Industries Animal Care and Ethics Committee research authority (ACEC 06/08). We thank landholders who provided access to their properties and assistance; Julia Sisson (University of New England) and Richard Gardiner for field assistance; Laura Rayner and Leroy Gonsalves (Australian Catholic University) for laboratory assistance; and Jennifer Spencer, Sharon Bowen, Sarah Imgraben, Louise Goggin and Keith Osborn for comments. We thank two anonymous reviewers for constructive criticisms. Logistic support was provided by Bill Johnson, Renee Shepherd, Daryl Albertson, Michael Maher, Tim Pritchard and Klaus Koop (DECCW) and Suzanne Hollins (ANSTO). The views and conclusions expressed in this paper are those of the authors and do not necessarily represent the official policies, either expressed or implied, by the respective organisations.


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