Status of Caribbean coral reefs after bleaching and hurricanes in 2005

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Status of Caribbean Coral Reefs after Bleaching and Hurricanes in 2005These relationships mean that the effectiveness of broader efforts to reduce the rate andextent of global climate change will have significant implications for the effectiveness of localmanagement initiatives. Implementing local management actions, such as those below, willenhance the resilience of coral reefs and ‘buy time’ to implement actions that will reducethe impacts of global climate change. However, if moderate or pessimistic projections forclimate change eventuate, the resulting effects on reefs may overwhelm local managementefforts aimed at maintaining coral-dominated systems.The targets for action at a global level were articulated by coral reef managers and scientistsat the 3rd International Tropical Marine Environment Management Symposium (ITMEMS)in October 2006. Conference participants adopted the ‘Coral Reefs and Climate Change’statement, which called on senior decision-makers to “limit climate change to ensure thatfurther increases in sea temperature are limited to 2oC above pre-industrial levels and oceancarbonate ion concentrations do not fall below 200 μmol.kg -1 ” (http://www.icriforum.org/secretariat/japangm/docs/Coral_Reefs_Climate_Change_Brief.pdf). These recommendationswere based on published projections of the temperatures at which severe bleaching eventsbecome an annual phenomenon and reef calcification rates become negative (Chap. 2).Coral reef managers can provide a powerful impetus for policy responses to climate change bygenerating their own compelling stories about the plight of reefs under their jurisdiction. Reefmanagers can document and communicate about the ecological and socioeconomic effects ofmass coral bleaching, like those in the Caribbean during 2005. Two publications listed in thereferences that offer technical guidance on evaluating the impacts of mass bleaching are AGlobal Protocol for Assessment and Monitoring of Coral Bleaching (7) and A Reef Manager’sGuide to Coral Bleaching (5). The latter offers suggestions for communicating about masscoral bleaching with key audiences (e.g. decision-makers, stakeholders, colleagues, and thegeneral public) before, during, and after bleaching events.Strategy 2. Integrate resilience into Marine Protected Area networks.MPAs are important tools in coral reef management and can help achieve many of themanagement goals identified above. Traditionally, the principles of MPA selection, design, andmanagement have not specifically addressed the threat of mass bleaching. Integrating thefollowing considerations into existing or developing MPA networks will optimize the role MPAscan play in supporting coral reef ecosystem resilience to mass bleaching:zx Refugia - Sites with natural resistance or tolerance to mass coral bleaching shouldbe considered as sites warranting high protection in MPA networks. These ‘lucky’areas can serve as source reefs that provide new coral larvae to morezx Representation and replication – To maximize biological diversity, MPA networksshould aim to provide high levels of protection to sufficient areas of all habitat types.Rather than only protecting certain kinds of reefs, networks should aim to includerepresentatives of all reef types and associated habitats at replicate sites. This is arisk-spreading approach that helps to account for the uncertainty associated withglobal climate change.zx Connectivity – Incorporating knowledge about connectivity into the selectionand arrangement of sites that will receive higher levels of protection can promoterecovery after mass bleaching and other disturbances. Linking highly-protected122
Managing for Mass Coral Bleaching: Strategies for Supporting Socio–ecological Resilienceareas along prevailing, larvae-carrying currents can replenish downstream reefs,increasing the probability of recovery at multiple coral reef sites. Non-reef areasadjacent to highly-protected reefs may also warrant increased protection becausethey can become staging areas for coral recruits as they move between reefs.zx Good ecosystem condition – High coral cover, abundant fish populations, and goodwater quality are all elements of coral reef health that support recovery. Maintaining,enhancing, or restoring these valuable characteristics through managementinterventions are easier to achieve in some areas than others, because of variousattributes of site location and use. In developing MPA networks, it is useful toconsider whether additional management protection can be effective in maintainingthese resilience-supporting qualities of ecosystem condition.These principles are already being implemented into MPA networks around the world,including: Palau; the British Virgin Islands; Belize; the Seychelles; Yemen; and the Maldives.The Nature Conservancy’s Reef Resilience (R2) Toolkit (8) or website (www.reefresilience.org)has a more detailed discussion of how to identify resilient areas and incorporate these areasinto MPA design.Strategy 3. Reduce local stressors to build coral tolerance to bleaching.Global climate change will add stress to coral reefs; therefore the removal of local stressors canhelp corals respond to these new, difficult conditions. Removing chronic local stressors causedby intensive tourism use, water pollution, or over-fishing can increase coral reef health andlipid levels. Corals with higher energy reserves are more likely to survive a bleaching event.Removal of acute stressors to corals during bleaching events is also likely to increase theirability to survive. Bleached corals are extremely stressed and have a reduced capacity formaintenance of essential functions, such as injury repair, resistance to pathogens, and defenceagainst competitors. A stressed coral is less capable of recovering from physical injuries causedby careless snorkeling, diving, and boat anchoring. Repair of even minor tissue damage maybe hindered for a stressed coral, thereby increasing the risk of infection or overgrowth bycompeting organisms. Acute increases in sediments and pollutants from coastal development ordredging will deliver additional stress to corals that must clear sediment from colony surfaces,wasting precious physiological resources. Bleached corals are also less effective at defendingagainst invasion by microalgae or competing with macroalgae. These coral competitors benefitfrom increases in nutrients or reductions in the herbivorous fish populations that consumethem. Therefore, management can promote coral survival during mass bleaching events bylimiting damage from recreation, degraded water quality, and fishing pressures.Strategy 4. Protect, maintain or enhance the conditions that promote ecosystem recovery.Coral cover, water quality, and herbivorous fish abundance are critical in determining reefrecovery through their influence on processes, including: larval supply; availability ofsubstrate for settlement; coral recruitment rates; and survival of juvenile corals. Traditionalmanagement strategies may be based on the assumption that reefs are likely to continue inrelatively stable condition. As reefs spend more time in recovery mode, management targetsmay need to become more conservative to achieve satisfactory water quality, fish abundances,and coral cover. For example, water quality standards and fishery management regimes should123
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Dedication: This book is dedicated
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Status of Coral Reefs in the Caribb
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3. Hu r r i ca n e s a n d t h e i
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Hurricanes and their Effect on Cora
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Hurricanes and their Effect on Cora
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4. Th e 2005 Bl e a c h i n g Ev e
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The 2005 Bleaching Event: Coral-Lis
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Coral Reefs of the U.S. Caribbean19
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Status of Caribbean coral reefs after bleaching and hurricanes in 2005

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