Coral Reefs

, Volume 25, Issue 3, pp 361-368

First online:

Chronic parrotfish grazing impedes coral recovery after bleaching

  • Randi D. RotjanAffiliated withDepartment of Biology, Tufts University Email author 
  • , James L. DimondAffiliated withDepartment of Biological Sciences, University of Rhode Island
  • , Daniel J. ThornhillAffiliated withInstitute of Ecology, University of Georgia
  • , James J. LeichterAffiliated withScripps Institution of Oceanography, UCSD
  • , Brian HelmuthAffiliated withDepartment of Biological Sciences and Marine Science Program, University of South Carolina
  • , Dustin W. KempAffiliated withInstitute of Ecology, University of Georgia
  • , Sara M. LewisAffiliated withDepartment of Biology, Tufts University

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Coral bleaching, in which corals become visibly pale and typically lose their endosymbiotic zooxanthellae (Symbiodinium spp.), increasingly threatens coral reefs worldwide. While the proximal environmental triggers of bleaching are reasonably well understood, considerably less is known concerning physiological and ecological factors that might exacerbate coral bleaching or delay recovery. We report a bleaching event in Belize during September 2004 in which Montastraea spp. corals that had been previously grazed by corallivorous parrotfishes showed a persistent reduction in symbiont density compared to intact colonies. Additionally, grazed corals exhibited greater diversity in the genetic composition of their symbiont communities, changing from uniform ITS2 type C7 Symbiodinium prior to bleaching to mixed assemblages of Symbiodinium types post-bleaching. These results suggest that chronic predation may exacerbate the influence of environmental stressors and, by altering the coral-zooxanthellae symbiosis, such abiotic-biotic interactions may contribute to spatial variation in bleaching processes.


Predation Coral bleaching Trophodynamics Environmental stress Zooxanthellae Symbiodinium