Within-colony feeding selectivity by a corallivorous reef fish: foraging to maximize reward?

Brooker, Rohan M., Jones, Geoffrey P., and Munday, Philip L. (2013) Within-colony feeding selectivity by a corallivorous reef fish: foraging to maximize reward? Ecology and Evolution, 3 (12). pp. 4109-4118.

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Foraging theory predicts that individuals should choose a prey that maximizes energy rewards relative to the energy expended to access, capture, and consume the prey. However, the relative roles of differences in the nutritive value of foods and costs associated with differences in prey accessibility are not always clear. Coral-feeding fishes are known to be highly selective feeders on particular coral genera or species and even different parts of individual coral colonies. The absence of strong correlations between the nutritional value of corals and prey preferences suggests other factors such as polyp accessibility may be important. Here, we investigated within-colony feeding selectivity by the corallivorous filefish, Oxymonacanthus longirostris, and if prey accessibility determines foraging patterns. After confirming that this fish primarily feeds on coral polyps, we examined whether fish show a preference for different parts of a common branching coral, Acropora nobilis, both in the field and in the laboratory experiments with simulated corals. We then experimentally tested whether nonuniform patterns of feeding on preferred coral species reflect structural differences between polyps. We found that O. longirostris exhibits nonuniform patterns of foraging in the field, selectively feeding midway along branches. On simulated corals, fish replicated this pattern when food accessibility was equal along the branch. However, when food access varied, fish consistently modified their foraging behavior, preferring to feed where food was most accessible. When foraging patterns were compared with coral morphology, fish preferred larger polyps and less skeletal protection. Our results highlight that patterns of interspecific and intraspecific selectivity can reflect coral morphology, with fish preferring corals or parts of coral colonies with structural characteristics that increase prey accessibility.

Item ID: 32080
Item Type: Article (Research - C1)
ISSN: 2045-7758
Keywords: Acropora; corallivory; optimal foraging theory; Oxymonacanthus longirostris; predator–prey interactions; prey morphology
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This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Funders: Marine and Tropical Sciences Research Facility, ARC Centre of Excellence for Coral Reef Studies
Date Deposited: 20 Mar 2014 23:41
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 100%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 100%
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