Status of Caribbean coral reefs after bleaching and hurricanes in 2005

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Executive Summaryand flooding from the land, thereby adding an additional stress to already stressed reefs. Lowto moderate strength hurricanes can be beneficial during summer, however, by cooling surfacewaters and reducing the likelihood of coral bleaching.There is insufficient evidence or indications that the other potential climate change stresseswill result in significant damage to coral reefs. There is a potential for negative impacts frompossible shifting of ocean currents or rises in UV concentrations; however these are not evidentat the moment. Sea level rise will not directly threaten corals, but may render coral reef islandsuninhabitable, thereby threatening coral island cultures and nations.Implications o f 2005 f o r Co r a l Ma n a g e r sCoral reef managers were unprepared for the climate-related destructive events of 1998. Manycoral reef managers in the Indian Ocean and Western Pacific reported that massive coralbleaching in mid to late 1998 was devastating their coral reefs, and they asked ‘what have I donewrong to cause the corals to die’. They were perplexed that corals were dying on the same reefsthat they were actively managing to remove pollution, sedimentation and over-fishing stresses.The cause of the problems to their reefs was related to climate change via a particularly severeEl Niño and La Niña climate switch that raised sea surface temperatures (SSTs) above levelsthat had ever been recorded on those coral reefs. We now know that no management actionscould have prevented the extent of coral death; the only advice the coral reef research andmanagement community could offer was that ‘better managed reefs will recover more rapidlythan those under human stresses’.The events of 1998 stimulated the international coral reef community to develop advice forcoral reef managers faced with similar circumstances in the future. A Reef Manager’s Guideto Coral Bleaching was developed in 2006 to provide that advice for coral reef managers facedwith stresses beyond their immediate control. The report is summarized by the authors inChapter 10 and provides reef managers with the explanations why reefs are damaged by suchclimate related events and explains why some reefs resist coral bleaching and others are moreresilient i.e. they recover faster after severe losses.The report guides reef managers into steps they can take at national and global levels to raiseawareness of the potential devastation that increasing global climate change, though the releaseof greenhouse gases, can have on coral reefs. However, the emphasis is on providing managerswith practical advice on how to increase protection of those reefs that are either naturallyresistant or tolerant to bleaching, assist in promoting adaptation mechanisms that enhance reefresilience, while simultaneously reducing local pressures on the reefs and nearby ecosystemsto enhance chances for natural recovery. Importantly, the Guide advises reef managers on howto engage with local people and assist in maintaining socioeconomic well-being and bringingthem on board to assist in the sustainable use of their coral reefs.An d t h e Fu t u r eSadly for coral reefs, all predictions from the Intergovernmental Panel on Climate Change(IPCC) reports in 2007 indicate that the extreme warming of 2005 will not be an isolated event(Chapter 11). It will probably happen again in the future and, when it does, the impacts willbe even more severe. The IPCC concluded that human-induced climate change will warm the13
Status of Caribbean Coral Reefs after Bleaching and Hurricanes in 2005world by 1.8 to 4.0ºC by the year 2100. This warming will affect most of the wider CaribbeanSea making years like 2005 more common and more devastating for coral reefs.In addition, increasing acidity in the seawater with the solution of more CO 2 will result inslower growth of corals that are trying to recover from bleaching and other disturbances.One other potential consequence of the human-induced warming is an increase in the frequencyof more damaging Category 4 and 5 hurricanes in the Caribbean. These storms develop aswaters warm over the tropical North Atlantic and Caribbean waters. It is predicted that warmersurface waters with increased amounts of thermal energy will fuel increases in tropical stormstrength. The latest predictions are for an increase in the more intense Category 4 and 5hurricanes that will probably cause significant damage to the coral reefs and the communitiesthat depend upon them (Chapter 3).50% Hurricanes per category40302010Category 1Category 2 & 3Category 4 & 5070-74 75-79 80-84 85-89 90-94 95-99 00-04 05-09 10-14 14-195 – year periodThis figure shows the proportion of intense hurricanes has been increasing since 1970 while thetotal number of hurricanes has not changed much. These graphs plot all global hurricanes combinedinto 5 year periods from 1970 to 2004, with projected trends added to 2019. Category 1 storms arerelatively weak whereas Category 5 storms are particularly devastating (adapted from Webster 2005).Dashed lines show significant linear trends.This is a pivotal moment for the coral reefs. The world is already committed to some furtherwarming due to past greenhouse gas emissions and the expected emissions from existing worldenergy infrastructure (Chapter 2). Thanks to more than a century of ‘committed warming’;events like 2005 are expected to occur more frequently by the 2030s. The only possible way tosustain some live coral on the reefs around the world will be to carefully manage the directpressures like pollution, fishing and damaging coastal developments, and hope that somecoral species are able to adapt to the warmer environment. However, a dramatic reduction ingreenhouse gas emissions in the next 20 years will be critical to control further warming andhigher CO 2levels that will probably reduce the robustness and competitive fitness of corals andlimit the habitats for many other organisms living on Caribbean coral reefs.14
Page 1 and 2: Stat u s o fCa r i b b e a nCo r a
Page 3 and 4: Dedication: This book is dedicated
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Page 25 and 26: Status of Coral Reefs in the Caribb
Page 35 and 36: 3. Hu r r i ca n e s a n d t h e i
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Page 41 and 42: 4. Th e 2005 Bl e a c h i n g Ev e
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7. Th e Effects o f Co r a l Bl e a
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The Effects of Coral Bleaching in t
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10. Ma n ag i n g f o r Ma s s Co r
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Managing for Mass Coral Bleaching:
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Status of Caribbean coral reefs after bleaching and hurricanes in 2005

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