The Dynamics of Coral Disease and Bleaching
Coral reefs of the Caribbean have been severely degraded over the last few decades through the impacts of coral diseases and bleaching (Gladfelter 1982, Gardener et al. 2003, Rogers et al. 2008, Woody et al. 2008). While the proximate causes of these signs of coral impairment are sometimes known, such as temperature and irradiance initiation of coral bleaching (Glynn 1996), the direct causes of many other reduced coral health states remain enigmatic. Coral bleaching (Fig. 1) and disease outbreaks (Fig. 2 & 3) and are believed to be increasing in incidence and severity (Harvell et al. 2005; Hoegh-Gulberg et al.
2007). Paralleling this increase in causes of coral degradation, global and local stressors in waters surrounding Caribbean islands are also increasing, and their combined and synergistic impacts may be the ultimate driver of coral bleaching and disease (Knowlton 2001; Hughes et al. 2003). These stressors range from increasing sea surface temperature (Levitus et al. 2000) and ocean acidification (Gledhill et al. 2008), to already high levels of sediment loading (MacDonald et al.
1997, Smith et al. 2008), fishing (Jackson et al. 2001), and toxins (Carbery et al.
2006). A major task of modern coral reef biology is to reveal the connection between these stressors and the causes and consequences of coral disease and bleaching.
Fig. 1
The US Virgin Islands has also suffered under the impact of coral disease and bleaching in the last few decades and is a natural laboratory for investigating these threats to coral reef persistence. In fact, many of the first and most well described examples of Caribbean disease and bleaching have come from the USVI. The Center for Marine and Environmental Studies is actively engaged in research into the connection between global and local stressors and causes and consequences of coral diseases and bleaching on scales ranging from the seascape to individual corals. This research uses high-resolution monitoring of coral stress factors, such as temperature, sediment, and nutrient-loading, and widespread coral reef sampling, such as repetitive monitoring and targeted
sampling of specific events, such as disease outbreaks and mass coral bleaching episodes. We are also investigating the relationship between coral symbiont (zooxanthellae) diversity, and coral disease and bleaching.
Recent progress within this research theme has led to new insights into the seascape scale patterns of coral disease and bleaching and the processes that increase and reduce their impacts. Research highlights include:
• The susceptibility of individual coral species to coral diseases in mid-depth and deep reefs of the USVI (Calnan et al. 2008)
• Linkages between nearshore stressors and chronic low-level bleaching and partial colony mortality (Smith et al. 2008)
• Outbreaks of a widespread and highly degrading disease in
mesophotic (> 30 m deep) coral reef refugia (Smith et al. in review)
• The connection between mass coral bleaching events and
seascape patterns of bleaching and disease; including degradation Fig. 2
Fig. 3
in a predicted coral reef refuge (Rogers et al. 2008, Woody et al.
2008, Smith et al. in prep)
• The reduction of coral bleaching due to hurricane cooling of sea surface temperatures (Manzello et al. 2007)
• The connection between symbiont diversity and susceptibility of Caribbean corals to diseases (Correa et al. 2009)
• The dynamics of coral symbiont diversity following the 2005 NE Caribbean mass bleaching event
Partners
NOAA-National Ocean Sciences Biogeography Program (director: M. Monaco) and Atlantic Oceanographic and Meteorological Laboratory (collaborator: D.P.
Manzello), the USVI Department of Planning and Natural Resources-Division of Coastal Zone Management (project manager: P. Rothenberger) and Department of Environmental Protection, The University of Miami (collaborators: M.E. Brandt, A.M.S. Correa, A.C. Baker).
Funding
National Ocean Sciences Biogeography and Coral Conservation Programs, the National Science Foundation VI-EPSCoR Program, the USVI Department of Planning and Natural Resources
Contact: Dr. Tyler B. Smith tsmith@uvi.edu +1-340-693-1394
Literature Cited and Other Relevant Publications
Calnan J, Smith T, Nemeth R, Kadison E, Blondeau J (2008) Coral disease prevalence and host susceptibility on mid-depth and deep reefs in the US Virgin Islands. Revista Biologia Tropical 56 (suppl. 1):223-224
Carbery K, Owen R, Frickers T, Otero E, Readman J (2006) Contamination of Caribbean coastal waters by the antifouling herbicide Irgarol 1051. Marine Pollution Bulletin 52:635-644Gardner TA, Côté IM, Gill JA, Grant A,
Watkinson AR (2003) Long-term region-wide declines in Caribbean corals.
Science 301:958-960
Correa A, Brandt M, Smith T, Thornhill D, Baker A (2009) Symbiodinium
associations with diseased and healthy scleractinian corals. Coral Reefs (in press). http://dx.doi.org/10.1007/s00338-008-0464-6
Gladfelter WB (1982) White-band disease in Acropora palmata - implications for the strucure and growth of shallow reefs. Bulletin of Marine Science 32:639-643
Gledhill DK, Wanninkhof R, Millero FJ, Eakin CM (2008) Ocean acidification of the Greater Caribbean Region 1996–2006. Journal of Geophysical Research 113:C10031
Glynn PW (1996) Coral reef bleaching: Facts, hypotheses and implications.
Global Change Biology 2:495-509
Harvell CD, Aronson RB, Baron N, Connell J, Dobson A, Ellner S, Gerber L, Kim K, Kurtis A, McCallum H, Lafferty K, McKay B, Porter JW, Pascual M, Smith G, Sutherland K, Ward J (2005) The rising tide of ocean diseases:
unsolved problems and research priorities. Frontiers in Ecology and the Environment 2:375-382
Hoegh-Guldberg O, Mumby PJ, Hooten AJ, Steneck RS, Greenfield P, Gomez E, Harvell CD, Sale PF, Edwards AJ, Caldeira K, Knowlton N, Eakin CM, Iglesias-Prieto R, Muthiga N, Bradbury RH, Dubi A, Hatziolos ME (2007) Coral Reefs Under Rapid Climate Change and Ocean Acidification.
Science 318:1737-1742
Jackson JBC, JKirby MX, Berger WH, Bjorndal KA, Botsford LW, Bourque BJ, Bradbury RH, Cooke R, Erlandson J, Estes JA, Hughes TP, Kidwell S, Lange CB, Lenihan HS, Pandolfi JM, Peterson CH, Steneck RS, Tegner MJ, Warner RR (2001) Historical Overfishing and the Recent Collapse of Coastal Ecosystems. Science 293:629-636
MacDonald L, Anderson D, Dietrich W (1997) Paradise threatened: land use and erosion on St. John, US Virgin Islands. Environmental Management 21:851-863
Manzello DP, Brandt ME, Smith TB, Lirman D, Hendee JC, Nemeth RS (2007) Hurricanes benefit bleached corals. Proceedings of the National Academy of Science 104:12035-12039
Rogers C, Miller J, Muller E, Edmunds PJ, Nemeth RS, Beets J, Friedlander AM, Smith T, Boulon R, Jeffery C, Menza C, Caldow C, Idrisi N, Kojis B,
Monaco ME, Spitzack T, Gladfelter B, Ogden J, Hillis-Starr Z, Lundgren I, Bane Schill W, Kuffner IB, Richardson L, Devine B, Voss JD (2008) Coral Reefs of the US Virgin Islands. In: Dodge R, Reigl B (eds) Coral Reefs of the World. Vol 1. Coral Reefs of the United States. Springer, New York, pp 803
Smith TB, Nemeth RS, Blondeau J, Calnan JM, Kadison E, Herzlieb S (2008) Assessing coral reef health across onshore to offshore stress gradients in the US Virgin Islands. Marine Pollution Bulletin 56:1983-1991
Smith TB, Blondeau J, Nemeth RS, Pittman SJ, Calnan J, Kadison E, Gass J (in review) Benthic structure and cryptic mortality in a Caribbean mesophotic coral reef bank system, the Hind Bank Marine Conservation District, U.S.
Virgin Islands. Coral Reefs (forthcoming special issue on mesophotic coral reefs)
Smith TB et al. (in prep) Refuges from coral bleaching may not be refuges from the effects of warming seawater temperatures
Woody K, Atkinson A, Clark R, Jeffrey C, Lundgren I, Miller J, Monaco M, Muller E, Patterson M, Rogers C, Smith TB, Spitzack T, Waara R, Whelan K, Witcher B, Wright A (2008) Coral Bleaching in the U.S. Virgin Islands in 2005 and 2006. In: Wilkinson C, Souter D (eds) Status of Caribbean Coral
Reefs After Bleaching and Hurricanes in 2005. Global Coral Reef Monitoring Network, and Reef and Rainforest Research Center, Townsville, pp 152
