Niche partitioning of feeding microhabitats produces a unique function for herbivorous rabbitfishes (Perciformes, Siganidae) on coral reefs

Fox, R.J., and Bellwood, D.R. (2013) Niche partitioning of feeding microhabitats produces a unique function for herbivorous rabbitfishes (Perciformes, Siganidae) on coral reefs. Coral Reefs, 32 (1). pp. 13-23.

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Niche theory predicts that coexisting species minimise competition by evolving morphological or behavioural specialisations that allow them to spread out along resource axes such as space, diet and temporal activity. These specialisations define how a species interacts with its environment and, by extension, determine its functional role. Here, we examine the feeding niche of three species of coral reef-dwelling rabbitfishes (Siganidae, Siganus). By comparing aspects of their feeding behaviour (bite location, bite rate, foraging distance) with that of representative species from two other abundant herbivorous fish families, the parrotfishes (Labridae, Scarus) and surgeonfishes (Acanthuridae, Acanthurus), we examine whether rabbitfishes have a feeding niche distinct from other members of the herbivore guild. Measurements of the penetration of the fishes' snouts and bodies into reef concavities when feeding revealed that rabbitfish fed to a greater degree from reef crevices and interstices than other herbivores. There was just a 40% overlap in the penetration-depth niche between rabbitfish and surgeonfish and a 45% overlap between rabbitfish and parrotfish, compared with the almost complete niche overlap (95%) recorded for parrotfish and surgeonfish along this spatial niche axis. Aspects of the morphology of rabbitfish which may contribute to this niche segregation include a comparatively longer, narrower snout and narrower head. Our results suggest that sympatric coexistence of rabbitfish and other reef herbivores is facilitated by segregation along a spatial (and potentially dietary) axis. This segregation results in a unique functional role for rabbitfishes among roving herbivores that of "crevice-browser": a group that specifically feeds on crevice-dwelling algal or benthic organisms. This functional trait may have implications for reef ecosystem processes in terms of controlling the successional development of crevice-based algal communities, reducing their potential to trigger macroalgal outbreaks.

Item ID: 23855
Item Type: Article (Research - C1)
ISSN: 1432-0975
Keywords: complementarity, crevice-browser, feeding niche, functional diversity, herbivory, resilience
Funders: Australian Research Council (ARC), Lizard Island Reef Research Foundation
Date Deposited: 30 Nov 2012 05:44
FoR Codes: 06 BIOLOGICAL SCIENCES > 0602 Ecology > 060205 Marine and Estuarine Ecology (incl Marine Ichthyology) @ 34%
06 BIOLOGICAL SCIENCES > 0606 Physiology > 060604 Comparative Physiology @ 33%
06 BIOLOGICAL SCIENCES > 0608 Zoology > 060807 Animal Structure and Function @ 33%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 50%
97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 50%
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