River and wetland food webs in Australia’s wet–dry tropics: general principles and implications for management
Michael M. Douglas A D , Stuart E. Bunn B and Peter M. Davies C
+ Author Affiliations
- Author Affiliations
A Tropical Wetlands Program, Charles Darwin University, Darwin, NT 0909, Australia.
B Centre for Riverine Landscapes, Griffith University, Nathan, Qld 4111, Australia.
C Centre of Excellence in Natural Resource Management, The University of Western Australia, Albany, WA 6330, Australia.
D Corresponding author. Email: michael.douglas@cdu.edu.au
Marine and Freshwater Research 56(3) 329-342 https://doi.org/10.1071/MF04084
Submitted: 22 November 2004 Accepted: 2 March 2005 Published: 3 June 2005
Abstract
The tropical rivers of northern Australia have received international and national recognition for their high ecological and cultural values. Unlike many tropical systems elsewhere in the world and their temperate Australian counterparts, they have largely unmodified flow regimes and are comparatively free from the impacts associated with intensive land use. However, there is growing demand for agricultural development and existing pressures, such as invasive plants and feral animals, threaten their ecological integrity. Using the international literature to provide a conceptual framework and drawing on limited published and unpublished data on rivers in northern Australia, we have derived five general principles about food webs and related ecosystem processes that both characterise tropical rivers of northern Australia and have important implications for their management. These are: (1) the seasonal hydrology is a strong driver of ecosystem processes and food-web structure; (2) hydrological connectivity is largely intact and underpins important terrestrial–aquatic food-web subsidies; (3) river and wetland food webs are strongly dependent on algal production; (4) a few common macroconsumer species have a strong influence on benthic food webs; and (5) omnivory is widespread and food chains are short. The implications of these ecosystem attributes for the management and protection of tropical rivers and wetlands of northern Australian are discussed in relation to known threats. These principles provide a framework for the formation of testable hypotheses in future research programmes.
Extra keywords: connectivity, floodplain, flood pulse, omnivory, primary production, stable isotopes.
Acknowledgments
Much of the authors’ research referred to in this review was supported by Land and Water Australia, Environment Australia and the Water and Rivers Commission (particularly Kerry Trayler and Roy Stone). Susan Creagh, Andrew Storey, Ruth O’Connor and Michelle Winning are thanked for their assistance with the collection and analysis of stable isotope data. This review was prepared with support from the Land and Water Australia Tropical Rivers Program. This manuscript was improved by suggestions from Craig Layman and two anonymous reviewers.
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