Chronic parrotfish grazing impedes coral recovery after bleaching
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.
KeywordsPredation Coral bleaching Trophodynamics Environmental stress Zooxanthellae Symbiodinium
The authors thank Sam Benson, Dan Miller, and Claudette DeCourley for diving assistance; Jeff Chabot for equipment design and data collection; Davey Kline, and Hiro Fukami for species identification; Michael Reed for statistical advice; William Fitt, Gregory Schmidt, James Porter, Ken Sebens, Emily Carrington, Todd LaJeunesse, and Mike Lesser provided insightful comments. Peter Mumby and two anonymous reviewers greatly improved this manuscript. We thank Mike Carpenter and Klaus Ruetzler for their kind support and William Fitt and Gregory Schmidt for their generous lab support and funding for the genetic aspects of this study (NSF 9906976 and 0137007 Fitt). This research was funded by the Smithsonian Caribbean Coral Reef Ecosystems Program (CCRE contribution #718), the Tufts Institute for the Environment, and PADI Project AWARE (to RDR).
- Garzon-Ferreira J, Reyes-Nivia MC (2001) Incidence of fish predation on stony corals at four atolls of the archipelago of San Andres and Providencia (Colombian Caribbean). Bol Inv Mar Costeras 30:133–150Google Scholar
- Hughes TP (1994) Catastrophes, phase shifts, and large scale degradation of a Caribbean coral reef. Science 256:1574–1551Google Scholar
- Hughes TP, Baird AH, Bellwood DR, Card M, Connolly SR, Folke C, Grosberg R, Hoegh-Guldberg O, Jackson JBC, Kleypas J, Lough JM, Marshall P, Nystrom M, Palumbi SR, Pandolfi JM, Rosen B, Roughgarden J (2003) Climate change, human impacts, and the resilience of coral reefs. Science 301:929–933CrossRefGoogle Scholar
- Jones RJ (1997) Zooxanthellae loss as a bioassay for assessing stress in corals. Mar Ecol-Prog Ser 149:163–171Google Scholar
- LaJeunesse TC, Trench RK (2000) The biogeography of two species of Symbiodinium (Freudenthal) inhabiting the intertidal anemone Anthopleura elegantissima (Brandt). Biol Bull 199:126–134Google Scholar
- Meesters EH, Bak RPM (1993) Effects of coral bleaching on tissue regeneration potential and colony survival. Mar Ecol-Prog Ser 96:189–198Google Scholar
- Meesters EH, Noordeloos M, Bak RPM (1994) Damage and regeneration: links to growth in the reef-building coral Montastrea annularis. Mar Ecol-Prog Ser 112:119–128Google Scholar
- Nakamura T, van Woesik R (2001) Waterflow rates and passive diffusion partially explain differential survival of corals during the 1998 bleaching event. Mar Ecol-Prog Ser 212:301–304Google Scholar
- Rotjan RD, Lewis SM (2005) Selective predation by parrotfishes on the reef coral Porites astreoides. Mar Ecol-Prog Ser 305:193–201Google Scholar
- Rotjan RD, Lewis SM (2006) Parrotfish abundance and selective corallivory on a Belizean coral reef. J Exp Mar Biol Ecol (in press). DOI 10.1016/j.jembe.2006.03.015Google Scholar
- Sanchez JA, Gil MF, Chasqui LH, Alvarado EM (2004) Grazing dynamics on a Caribbean reef-building coral. Coral Reefs 23:578–583Google Scholar
- Stewart SR (2005) Tropical cyclone report: Hurricane Ivan. National Hurricane Center. http://www.nhc.noaa.gov/2004ivan.shtml?
- Toller WW, Rowan R, Knowlton N (2001a) Repopulation of zooxanthellae in the Caribbean corals Montastraea annularis and M. faveolata following experimental and disease-associated bleaching. Biol Bull 201:360–373Google Scholar
- Toller WW, Rowan R, Knowlton N (2001b) Zooxanthellae of the Montastraea annularis species complex: patterns of distribution of four taxa of Symbiodinium on different reefs and across depths. Biol Bull 201:348–359Google Scholar
- Van Veghel MLJ, Bak RPM (1994) Reproductive characteristics of the polymorphic Caribbean reef building coral Montastrea annularis. III. Reproduction in damaged and regenerating colonies. Mar Ecol-Prog Ser 109:229–233Google Scholar