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HSS revisited: multi-channel processes mediate trophic control across a productivity gradient.
Colette L Ward1,2, Kevin S McCann1, Neil Rooney3,4
1Department of Integrative Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1.
Ecology Letters
|August 28, 2015
Summary
Increasing productivity strengthens top-down control in marine food webs by subsidizing predators through detritus channels, supporting the apparent trophic cascade hypothesis (ATCH). This highlights multi-channel processes in ecosystem dynamics.
Area of Science:
- Ecology
- Marine Biology
- Ecosystem Dynamics
Background:
- Classical food web theory posits top-down control increases with productivity, driven by within-channel processes.
- This theory overlooks parallel energy channels and shared resources fueling generalist predators.
- Multi-channel processes can impose trophic control not accounted for in traditional models.
Discussion:
- This study analyzed 23 large marine food webs to test the apparent trophic cascade hypothesis (ATCH).
- Findings indicate that as productivity rises, predators increasingly utilize detritus channels, which are bottom-up controlled.
- This dietary shift subsidizes predator biomass, enhancing top-down control in parallel grazing channels.
Key Insights:
- Food web responses to increased productivity align with the ATCH.
- Detritus channels play a crucial role in mediating ecosystem responses to productivity changes.
- Multi-channel interactions are fundamental to understanding food web dynamics.
Outlook:
- The ATCH offers an alternative explanation for observed top-down control patterns.
- Future research should further explore the influence of detritus channels in diverse ecosystems.
- Understanding multi-channel processes is key for predicting food web stability under varying productivity.
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