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Predators indirectly induce stronger prey through a trophic cascade
Arie J P Spyksma1, Nick T Shears2, Richard B Taylor2
1Leigh Marine Laboratory, Institute of Marine Science, University of Auckland, Leigh, New Zealand spyksma.ap@gmail.com.
Proceedings. Biological Sciences
|November 3, 2017
Summary
Predators indirectly enhance sea urchin defenses by increasing food availability through trophic cascades. This food supply boost strengthens sea urchin (Evechinus chloroticus) skeletons more than direct predator cues.
Area of Science:
- Marine ecology
- Predator-prey dynamics
- Ecosystem engineering
Background:
- Prey species often develop defenses in response to direct predation.
- Predators can also indirectly enhance prey defenses by altering resource availability, such as through trophic cascades.
Purpose of the Study:
- To investigate the direct and indirect effects of predators on the mechanical strength of sea urchin tests.
- To compare the influence of food availability versus predator cues on sea urchin defense mechanisms.
Main Methods:
- Measured the crush-resistance of sea urchin (Evechinus chloroticus) tests in marine reserves (high predators, abundant food) and adjacent fished areas (low predators, scarce food).
- Conducted a six-month mesocosm experiment manipulating food supply and predator cues to assess their impact on test crush-resistance.
Main Results:
- Sea urchins in areas with abundant predators and food (kelp) exhibited significantly higher test crush-resistance compared to those in fished areas.
- Mesocosm experiments confirmed that both increased food supply and predator cues enhanced crush-resistance, with food supply having a greater effect.
Conclusions:
- Predators indirectly strengthen prey defenses (sea urchin test strength) via trophic cascades that increase resource availability.
- This indirect mechanism, driven by enhanced food supply, is a significant factor promoting prey persistence in the presence of predators.
Keywords:
indirect interactioninduced defencekelp foreststructural defencetemperate rocky reeftrophic cascadeMore Related Videos
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