, Volume 169, Issue 1, pp 187–198 | Cite as

Effects of herbivory, nutrients, and reef protection on algal proliferation and coral growth on a tropical reef

  • Douglas B. Rasher
  • Sebastian Engel
  • Victor Bonito
  • Gareth J. Fraser
  • Joseph P. Montoya
  • Mark E. Hay
Community ecology - Original Paper


Maintaining coral reef resilience against increasing anthropogenic disturbance is critical for effective reef management. Resilience is partially determined by how processes, such as herbivory and nutrient supply, affect coral recovery versus macroalgal proliferation following disturbances. However, the relative effects of herbivory versus nutrient enrichment on algal proliferation remain debated. Here, we manipulated herbivory and nutrients on a coral-dominated reef protected from fishing, and on an adjacent macroalgal-dominated reef subject to fishing and riverine discharge, over 152 days. On both reefs, herbivore exclusion increased total and upright macroalgal cover by 9–46 times, upright macroalgal biomass by 23–84 times, and cyanobacteria cover by 0–27 times, but decreased cover of encrusting coralline algae by 46–100% and short turf algae by 14–39%. In contrast, nutrient enrichment had no effect on algal proliferation, but suppressed cover of total macroalgae (by 33–42%) and cyanobacteria (by 71% on the protected reef) when herbivores were excluded. Herbivore exclusion, but not nutrient enrichment, also increased sediment accumulation, suggesting a strong link between herbivory, macroalgal growth, and sediment retention. Growth rates of the corals Porites cylindrica and Acropora millepora were 30–35% greater on the protected versus fished reef, but nutrient and herbivore manipulations within a site did not affect coral growth. Cumulatively, these data suggest that herbivory rather than eutrophication plays the dominant role in mediating macroalgal proliferation, that macroalgae trap sediments that may further suppress herbivory and enhance macroalgal dominance, and that corals are relatively resistant to damage from some macroalgae but are significantly impacted by ambient reef condition.


Plant-herbivory Eutrophication Fiji MPA Overfishing 



Marine protected area


Non-marine protected area


Crustose coralline algae


Relative dominance model


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Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Douglas B. Rasher
    • 1
  • Sebastian Engel
    • 1
  • Victor Bonito
    • 2
  • Gareth J. Fraser
    • 3
  • Joseph P. Montoya
    • 1
  • Mark E. Hay
    • 1
  1. 1.School of BiologyGeorgia Institute of TechnologyAtlantaUSA
  2. 2.Reef Explorer FijiKorolevuFiji
  3. 3.Department of Animal and Plant SciencesUniversity of SheffieldSheffieldUK

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