Coral Reefs

, Volume 30, Issue 2, pp 381–390 | Cite as

Spatial variation in the effects of grazing on epilithic algal turfs on the Great Barrier Reef, Australia

  • R. M. Bonaldo
  • D. R. Bellwood


Of all benthic components on tropical reefs, algal turfs are the most widespread and the main source of primary productivity. We compared the importance of grazing by herbivores on algal turfs on two zones with marked differences in terms of benthic composition, herbivore biomass and grazing pressure, the inner flat and crest, of an inshore reef on the Great Barrier Reef, Australia. A combination of herbivore exclusion cages and transplants of coral rubble covered by algal turfs between reef zones was used to examine changes in algal turfs over a 4-day experimental period. In situ crest turfs had lower algal height, sediment loads and particulate content than reef flat turfs. Caged samples on the crest exhibited an increase in all three variables. In contrast, in situ and caged treatments on the flat presented algal turfs with similar values for the three analysed variables, with high algal height and heavy particulate and sediment loads. In the absence of cages, reef flat turfs transplanted to the crest had decreased algal height, total particulate material and particulate inorganic content, while the opposite was found in crest turf samples transplanted to the flat. Our results highlight the dynamic nature of algal turfs and the clear differences in the relative importance of herbivory in shaping turf length and sediment load between the reef crest and inner flat.


Herbivory Epilithic algal matrix Benthic community Coral Reef Sediment 



We thank PR Guimarães-Júnior and C Syms for help with statistical analyses, JP Krajewski and C Lefevre for assistance in the field, J Tanner for comments on the manuscript, Orpheus Island Research Station staff for logistical support, colleagues in the ARC Centre of Excellence for helpful discussions, and the Australian Research Council Centre of Excellence for Coral Reef Studies and CAPES-Brazil for financial support.


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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  1. 1.Australian Research Council Centre of Excellence for Coral Reef Studies, and School of Marine and Tropical BiologyJames Cook UniversityTownsvilleAustralia
  2. 2.School of Biology, Georgia Institute of TechnologyAtlantaUSA

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