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RESEARCH ARTICLE
Contents Vol 61(8)

Food web dynamics in an Australian Wet Tropics river

Thomas S. Rayner A D E , Bradley J. Pusey B , Richard G. Pearson A and Paul C. Godfrey C
+ Author Affiliations
- Author Affiliations

A School of Marine and Tropical Biology, James Cook University, Townsville, Qld 4811, Australia.

B Tropical Rivers and Coastal Knowledge, Australian Rivers Institute, Griffith University, Nathan, Qld 4111, Australia.

C Australian Rivers Institute, Griffith University, Nathan, Qld 4111, Australia.

D Present address: School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia.

E Corresponding author. Email: thomas.rayner@unsw.edu.au

Marine and Freshwater Research 61(8) 909-917 https://doi.org/10.1071/MF09202
Submitted: 13 August 2009  Accepted: 4 January 2010   Published: 13 August 2010

Abstract

In Australia’s Wet Tropics rivers, perennial base flows punctuated by wet season floods drive instream responses across a range of spatial and temporal scales. We combined gut-content and stable-isotope analyses to produce preliminary webs depicting trophic links between fish, their main prey items and basal productivity sources. We then used these webs to test the applicability of general food web principles developed in other tropical systems. Although a range of sources appeared to underpin fish productivity, a large portion of total energy transfer occurred through a subset of trophic links. Variability in food web structure was negatively correlated with spatial scale, being seasonally stable at river reaches and variable at smaller scales. Wet Tropics rivers are similar to those in other tropical areas, but exhibit some unique characteristics. Their high degree of channel incision improves longitudinal connectivity, thereby allowing fish to move between mesohabitats and target their preferred prey items, rather than shifting their diet as resources fluctuate. However, this also inhibits lateral connectivity and limits terrestrial energy inputs from beyond the littoral zone.

Additional keywords: connectance, disturbance, flood, movement, pulse, scaling, seasonality.


Acknowledgements

This project was funded by grants from the Cooperative Research Centre for Tropical Rainforest Ecology and Management (Rainforest CRC) and James Cook University (JCU). Fish were collected under Queensland Department of Primary Industries – Fisheries permit PRM03040F and JCU Animal Care and Ethics permit A818_03. In-kind support was provided by Queensland Department of Primary Industries – Fisheries and Richard Hunt, Queensland Department of Natural Resources and Water. Field assistance was provided by Colton Perna, Zoe Baker, Paul Thuesen, Paul Godfrey, Amanda Soymonoff, Mo Healy, Anne Gulliard, Megan Barnes, Cameron Crothers-Stomp, Andrew Kaus, Andrew Jones, Rusty Ligon and Michael Pusey. Access to private land and other assistance in the field was provided by the Rossi, Thomasen and Moller families.


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