title: Investigating functional redundancy versus complementarity in Hawaiian herbivorous coral reef fishes.
abstract: Patterns of species resource use provide insight into the functional roles of species and thus their ecological significance within a community. The functional role of herbivorous fishes on coral reefs has been defined through a variety of methods, but from a grazing perspective, less is known about the species-specific preferences of herbivores on different groups of reef algae and the extent of dietary overlap across an herbivore community. Here, we quantified patterns of redundancy and complementarity in a highly diverse community of herbivores at a reef on Maui, Hawaii, USA. First, we tracked fish foraging behavior in situ to record bite rate and type of substrate bitten. Second, we examined gut contents of select herbivorous fishes to determine consumption at a finer scale. Finally, we placed foraging behavior in the context of resource availability to determine how fish selected substrate type. All species predominantly (73-100 %) foraged on turf algae, though there were differences among the types of macroalgae and other substrates bitten. Increased resolution via gut content analysis showed the composition of turf algae consumed by fishes differed across herbivore species. Consideration of foraging behavior by substrate availability revealed 50 % of herbivores selected for turf as opposed to other substrate types, but overall, there were variable foraging portfolios across all species. Through these three methods of investigation, we found higher complementarity among herbivorous fishes than would be revealed using a single metric. These results suggest differences across species in the herbivore "rain of bites" that graze and shape benthic community composition.
authors.affiliation: Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA. elkelly@ucsd.edu.
authors.forename: Emily L A
authors.initials: EL
authors.lastname: Kelly
authors.affiliation: Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
authors.forename: Yoan
authors.initials: Y
authors.lastname: Eynaud
authors.affiliation: Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
authors.forename: Samantha M
authors.initials: SM
authors.lastname: Clements
authors.affiliation: Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
authors.forename: Molly
authors.initials: M
authors.lastname: Gleason
authors.affiliation: Department of Land and Natural Resources, Division of Aquatic Resources, Maui Office, 130 Mahalani Street, Wailuku, HI, 96768, USA.
authors.forename: Russell T
authors.initials: RT
authors.lastname: Sparks
authors.affiliation: Coral Reef Ecosystem Program (CREP), Pacific Islands Fisheries Science Center (PIFSC), National Marine Fisheries Service, NOAA IRC, 1845 Wasp Blvd. Building 176, Honolulu, HI, 96818, USA.
authors.forename: Ivor D
authors.initials: ID
authors.lastname: Williams
authors.affiliation: Center for Marine Biodiversity and Conservation, Scripps Institution of Oceanography, University of California San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Smith
mesh_terms: D000818:Animals; D057894:Coral Reefs; D004463:Ecology; D005399:Fishes; D006254:Hawaii; D060434:Herbivory
keywords: Complementarity; Functional guild; Functional redundancy; Herbivore; Selectivity