Revisiting the functional roles of the surgeonfish Acanthurus nigrofuscus and Ctenochaetus striatus

A. Marshell, P. J. Mumby

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Investigating the functional role of herbivorous fish species is important for understanding reef resilience and developing targeted management plans. Among the most abundant fish species on Indo-Pacific coral reefs are the surgeonfishes Acanthurus nigrofuscus and Ctenochaetus striatus. A. nigrofuscus is an herbivorous grazer that crops filamentous algae from the epilithic algal matrix, while C. striatus is detritivorous and was thought to 'brush' detritus from the surface of filamentous algae, causing little damage to algal strands. Although the foraging mechanisms and general diet of these surgeonfishes have been established, their grazing impact on epilithic algal turfs has been unclear. This is the first study to quantify the grazing impact of A. nigrofuscus and C. striatus on algal turfs. Through aquaria trials using epilithic algal turf grown on experimental tiles, we found that both A. nigrofuscus and C. striatus consistently fed more intensively upon sparse/short algal turfs even though the yield of algae per bite was greater for dense/long algal turfs. As there was no difference in the nutritional value of sparse and dense algal turfs, we hypothesise that A. nigrofuscus avoided dense turf due to its significantly greater sediment load than sparse turf, while C. striatus likely avoided dense turf as it would become entangled in their bristle-like teeth. Unexpectedly, despite its dental morphology, C. striatus removed significantly more algal turf per hour than A. nigrofuscus, irrespective of canopy height. The capability of C. striatus to remove significant quantities of algal turf through their foraging activity implies that this abundant and widespread species may substantially affect algal turf dynamics. If this is the case, the exclusion of detritivorous Ctenochaetus species from herbivorous fish functional groups used in resilience monitoring will need to be re-evaluated.

Original languageEnglish
Pages (from-to)1093-1101
Number of pages9
JournalCoral Reefs
Volume31
Issue number4
DOIs
Publication statusPublished - 2012

Fingerprint

Acanthuridae
functional role
lawns and turf
algae
filamentous alga
fish
grazing
aquarium
teeth
detritus
functional group
coral reef
tooth
foraging
reef
alga
crop (digestive system)
canopy
diet
tiles

Keywords

  • Algal turf
  • Detritivore
  • Ecological role
  • Functional groups
  • Herbivore
  • Surgeonfish

ASJC Scopus subject areas

  • Aquatic Science

Cite this

Revisiting the functional roles of the surgeonfish Acanthurus nigrofuscus and Ctenochaetus striatus. / Marshell, A.; Mumby, P. J.

In: Coral Reefs, Vol. 31, No. 4, 2012, p. 1093-1101.

Research output: Contribution to journalArticle

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