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Consumer-resource coupling in wet-dry tropical rivers.
Timothy D Jardine1, Neil E Pettit, Danielle M Warfe
1Australian Rivers Institute, Griffith University, Nathan, QLD 4111, Australia. t.jardine@griffith.edu.au
The Journal of Animal Ecology
|November 23, 2011
Summary
Understanding fish diets in tropical rivers is challenging. Hydrological connectivity, not food availability, strongly influences fish resource use and food web dynamics.
Area of Science:
- Ecology
- Freshwater Biology
- Stable Isotope Ecology
Background:
- Consumer-diet links are crucial for food web stability but difficult to ascertain, especially in variable tropical freshwater systems.
- Seasonal hydrology creates dynamic connectivity patterns, influencing resource availability and consumer movement.
Purpose of the Study:
- To investigate broad patterns of resource use by freshwater consumers in Australia's wet-dry tropics.
- To determine how hydrological connectivity and floodplain inundation influence consumer-resource coupling.
Main Methods:
- Conducted a large-scale survey of freshwater biota across 67 sites in three Australian catchments.
- Analyzed stable carbon isotopes (δ(13)C) in biota and biofilms to assess food source reliance.
- Correlated isotope data with hydrological connectivity and floodplain inundation indices, and analyzed fish stomach contents.
Main Results:
- Benthic invertebrates showed strong coupling to local biofilm resources across all catchments.
- Fish carbon isotope ratios (δ(13)C) were less coupled to biofilms and varied significantly with catchment hydrological connectivity.
- The most connected river (Daly) showed the least fish-biofilm coupling, while the least connected (Fitzroy) showed the strongest coupling.
Conclusions:
- Fish mobility in these tropical rivers is high, overriding local resource availability in determining diet.
- Hydrological connectivity between habitats is a primary driver of consumer-resource coupling patterns in these dynamic ecosystems.
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