Not worth the risk: apex predators suppress herbivory on coral reefs

Rizzari, Justin R., Frisch, Ashley J., Hoey, Andrew S., and McCormick, Mark I. (2014) Not worth the risk: apex predators suppress herbivory on coral reefs. Oikos, 123 (7). pp. 829-836.

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Abstract

Apex predators are known to exert strong ecological effects, either through direct or indirect predator-prey interactions. Indirect interactions have the potential to influence ecological communities more than direct interactions as the effects are propagated throughout the population as opposed to only one individual. Indirect effects of apex predators are well documented in terrestrial environments, however there is a paucity of information for marine environments. Furthermore, manipulative studies, as opposed to correlative observations, isolating apex predator effects are lacking. Coral reefs are one of the most diverse ecosystems, providing a useful model system for investigating the ecological role of apex predators and their influence on lower trophic levels. Using predator models and transplanted macroalgae we examined the indirect effects of predators on herbivore foraging behaviour. We show that the presence of a model reef shark or large coral-grouper led to a substantial reduction in bite rate and species richness of herbivorous fishes and an almost absolute localized cessation of macroagal removal, due to the perceived risk of predation. A smaller-sized coral-grouper also reduced herbivore diversity and activity but to a lesser degree than the larger model predators. These indirect effects of apex predators on the foraging behaviour of herbivores may have flow-on effects on the biomass and distribution of macroalgae, and the functioning of coral reef ecosystems. This highlights that the ecological interactions and processes that contribute to ecosystem resilience may be more complex than previously assumed.

Item ID: 38084
Item Type: Article (Research - C1)
ISSN: 1600-0706
Funders: ARC Centre of Excellence for Coral Reef Studies, School of Marine and Tropical Biology, James Cook University (JCU)
Date Deposited: 31 Mar 2015 04:09
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 100%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 100%
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