Impact of conservation areas on trophic interactions between apex predators and herbivores on coral reefs

Rizzari, Justin R., Bergseth, Brock J., and Frisch, Ashley J. (2015) Impact of conservation areas on trophic interactions between apex predators and herbivores on coral reefs. Conservation Biology, 29 (2). pp. 418-429.

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Abstract

Apex predators are declining at alarming rates due to exploitation by humans, but we have yet to fully discern the impacts of apex predator loss on ecosystem function. In a management context, it is critically important to clarify the role apex predators play in structuring populations of lower trophic levels. Thus, we examined the top-down influence of reef sharks (an apex predator on coral reefs) and mesopredators on large-bodied herbivores. We measured the abundance, size structure, and biomass of apex predators, mesopredators, and herbivores across fished, no-take, and no-entry management zones in the Great Barrier Reef Marine Park, Australia. Shark abundance and mesopredator size and biomass were higher in no-entry zones than in fished and no-take zones, which indicates the viability of strictly enforced human exclusion areas as tools for the conservation of predator communities. Changes in predator populations due to protection in no-entry zones did not have a discernible influence on the density, size, or biomass of different functional groups of herbivorous fishes. The lack of a relationship between predators and herbivores suggests that top-down forces may not play a strong role in regulating large-bodied herbivorous coral reef fish populations. Given this inconsistency with traditional ecological theories of trophic cascades, trophic structures on coral reefs may need to be reassessed to enable the establishment of appropriate and effective management regimes.

Item ID: 38087
Item Type: Article (Research - C1)
ISSN: 1523-1739
Keywords: ecosystem function, Great Barrier Reef, herbivory, marine reserve, reef shark, top-down control, trophic structure
Funders: ARC Centre of Excellence for Coral Reef Studies, School of Marine and Tropical Biology, James Cook University (JCU), Australian Museum
Date Deposited: 31 Mar 2015 04:10
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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