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 2005Co r a l Bl e a c h i n g in t h e U.S. Virgin Is l a n d s in 2005 a n d 2006Kim b e r ly Wo o dy, An d r e a At k i n s o n, Ra n dy Cl a r k,Ch r i s Jeffrey, Ia n Lu n d g r e n, Jeff Miller, Ma r k Mo n ac o,Er i n n Muller, Mat t Pat t e rs o n, Ca ro l i n e Ro g e r s, Ty l e r Sm i th ,To n y Sp i t z a k, Ro b Wa a r a, Kev i n Wh e l a n, Br i a n Wi tc h e r a n dAl e x a n d r a Wr i gh t.Su m m a r yzx Severe coral mortality occurred in the U.S. Virgin Islands (USVI) between July andNovember, 2005 because of bleaching and disease; the average decline in hard coralcover was 51.5%;zx Sea surface temperatures exceeded the 29.5 o C coral bleaching threshold for 12 weeksin 2005; maximum temperatures exceeded 30 o C. The reefs suffered more thermalstress during this period than during the previous 20 years combined;zx Coral bleaching was observed between July and November, 2005; on average itaffected more than 90% of the coral cover;zx Bleaching occurred in 22 coral species over a wide range of depths;zx The greatest bleaching-related mortality occurred in the genus Agaricia; bleachingalso severely affected Montastraea, Colpophyllia, Diploria and Porites, but mortalityin these species was usually the result of subsequent infection by white plague orwhite syndrome;zx Coral losses in late summer 2005 were more severe than any time in the last 40years.In t r o d u c t i o nThe first indications of potential thermal stress to the corals of the USVI occurred in July 2005with observations of bleached corals, and in August when satellite information provided by theNational Environmental Satellite, Data, and Information Service (NESDIS) Coral Reef Watchindicated that sea surface temperatures (SSTs) in the north-eastern Caribbean were higherthan normal. Temperatures continued to rise, producing more thermal stress during thissingle period than during the previous 20 years combined (Coral Reef Watch 2005, accessed19 November 2007). The bleaching threshold of 29.5°C (83.3°F) was exceeded for about 12weeks prior to 12 November 2005, with SSTs reaching just over 30°C; a full degree warmerthan the previous year. This chapter discusses how monitoring efforts in the USVI captured thebleaching event of 2005 and demonstrates that several methods used to monitor the health ofthe reefs arrived at the same conclusion: coral cover on USVI reefs is declining.68
Coral Reefs of the U.S. CaribbeanSea surface temperatures (SSTs) in 2005 exceeded those of 2004, especially between August andNovember (solid line) when they exceeded the coral bleaching threshold of 29.5°C in the USVI (dashedline). The accumulation of ‘Degree Heating Weeks’ (DHW) is shown along the X-axis in red alongwith the timing of bleaching watches and warnings issued in 2004 and the major alerts in 2005from August to November. The thermal condition is categorized according to the five bleaching alertlevels defined by Coral Reef Watch’s Satellite Bleaching Alert. Source: http://coralreefwatch.noaa.gov/satellite/current/sst_dhw_series_usvirgin_cur.htmlEffects o f t h e 2005 Bl e a c h i n g Ev e n tDeclines in coral cover and increases in macroalgae resulting from a variety of stresses includinghurricanes and coral disease have been reported previously in the USVI. For example, majorcoral losses occurred in the 1970s and 1980s as a result of white band disease, killing more than90% of Acropora cervicornis and A. palmata colonies, the primary shallow water reef buildingcorals. However, the 51.5% decline in mean coral cover during the 12 months following themajor 2005/06 bleaching and disease event was unprecedented. These losses occurred on welldeveloped ‘high’ coral cover, high coral diversity reefs being monitored by the National ParksService. Even deep reefs with high coral cover (>30% cover, >30 m) were affected by bleachingand disease.National Park Service Inventory and Monitoring (NPS I&M) and US Geological Survey (USGS)scientists documented the effects of the 2005 bleaching and subsequent coral disease at longtermmonitoring sites around St. John and St. Croix. An average of 90% of the coral coverbleached at 5 permanent sites (100 transects at depths between 4 m and 19 m) in St. Johnand St. Croix, including Virgin Islands National Park (VINP) and Buck Island Reef NationalMonument (BIRMN). By late 2005, many of the corals began to regain color; but then becameinfected by the white plague coral disease. In just one year, the average decline in coral coverat these sites was 51.5% (range 34.1% - 61.8%). There were massive declines in the majorreef building coral species: the Montastraea annularis (complex) once comprised 80% ofthe total coral cover, but suffered a 51% decline compared with pre-2005 levels; the cover ofAgaricia agaricites, Colpophyllia natans and Porites porites declined by 87%, 78%, and 48%respectively. However, there was no change in cover of M. cavernosa. While mortality of A.agaricites was directly attributable to bleaching, mortality in nearly all other coral species69
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Stat u s o fCa r i b b e a nCo r a
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Dedication: This book is dedicated
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Status of Caribbean Coral Reefs aft
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Status of Caribbean coral reefs after bleaching and hurricanes in 2005

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