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 2005ColombiaIn t r o d u c t i o nThe Caribbean coast of Colombia has reefs on a 40 km wide continental shelf, which are stronglyinfluenced by freshwater and sediment runoff, particularly from the Magdalena River, which isthe largest river flowing into the Caribbean. The coral reefs cover more than 2800 km 2 and arescattered among 26 areas in 3 major groups. The mainland coast has fringing reefs on rockyshores, such as the Santa Marta and Urabá areas. There are many well-developed reefs aroundoffshore islands, including the Islas de San Bernardo and Islas del Rosario, on the continentalshelf, and oceanic reef complexes of the San Andrés Archipelago in the Western Caribbean.These are the best developed coral formations, including atolls, banks, barrier reefs, fringingreefs and patch reefs, and comprise more than 75% of Colombia’s coral reefs. Pacific reefs arepoorly developed, with only Gorgona Island having large coral formations.Stat u s o f Co r a l Reefs Pr i o r to 2005The Caribbean reefs were degraded by pollution, sedimentation, over-fishing, dynamite fishing,and coral mining during the 1980s, with mass mortality of gorgonians, coral bleaching,and declines in sea urchin (Diadema antillarum) populations. Bleaching was reported onColombian Caribbean reefs in 1987, 1990, 1995 and 1998. The 1987 Caribbean-wide eventaffected the Santa Marta region, Rosario Islands and Bahía Portete (Guajira area), but was poorlydocumented. During 1990 and 1995, minor bleaching events were observed at Islas del Rosarioand Chengue respectively. The 1997-98 El Niño event had little effect on Colombian Caribbeanreefs. Coral bleaching affected less than 5% of coral colonies at sites monitored between 1998and 2001, except in Chengue where it was 10%; but coral mortality was negligible. However,coral communities in Chengue were damaged in late 1999 by Hurricane Lenny, reducing coralcover from 35% to 31%. Colombian Caribbean reefs have changed little since the mid-1990s;coral cover has ranged between 31% and 35% in Chengue Bay, 28% and 32% at Rosario Islands,and 22% and 28% at San Andrés Island. Coral diseases affect less than 5% of coral colonies atall sites, except San Andrés, where 9.1% and 6.3% of colonies were affected in 1999 and 2001respectively. Dark spot and white plague are the most common coral diseases on Colombia’sCaribbean reefs.IDENTIFICATION OF BLEACHING-SUSCEPTIBLEZOOXANTHELLAE IN COLOMBIAN CORALS.Bleached colonies of Colpophyllia natans, Montastraea faveolata, M. annularis, Agariciatenuifolia, and Porites astreoides from the coral reefs near Cartagena, Colombia wereexamined with molecular techniques to identify bleaching resistance or susceptibilityin the zooxanthellae; 41.7% of bleached corals contained zooxanthellae clades A, C andD. There were however, many different sub-types of zooxanthellae in clades A and C,with most of these types susceptible to bleaching in 2005. When colonies of Montastraeafaveolata and Diploria labyrinthiformis were re-sampled after the bleaching event, thezooxanthellae were predominantly of thermally tolerant clade D, corresponding withpredictions of thermal acclimation (from Maria Clara Hurtado, mar-hurt@uniandes.edu.co and Juan Armando Sánchez, juansanc@uniandes.edu.co)108
The Effects of Coral Bleaching in Southern Tropical America: Brazil, Colombia, and VenezuelaEffects o f t h e 2005 Bl e a c h i n g Ev e n tSurface waters in Colombia were unusually warm in 2005. The first increases in sea temperaturealong the Caribbean coast were observed in mid-May and peaked at 1.5-2.5°C higher than themonthly mean in the 3rd and 4th weeks of June. This coincided with the first observations ofmass coral bleaching at Islas del Rosario.The 2005 bleaching event was the most severe for the Colombian Caribbean in the last 25years. The severity of bleaching varied between the 137 study sites: Rosario and San Bernardosuffered severe bleaching; San Andrés and Providencia were moderately affected; and SantaMarta experienced minimal bleaching. However, corals in the Santa Marta area bleached inOctober, 4 months after corals on reefs such as Islas del Rosario, which is 200 km to thesouthwest. This might have been a result of seasonal upwelling peaks that occurred early inthe year and in July-August.There was great variation between sites, with the cover of bleached coral and the proportionof bleached colonies ranging between 0.5-80% and 0.6-100% respectively. However, coralmortality was generally low with less than 5% variation between areas and stations. Mostcoral species showed some bleaching, especially those in water shallower than 10 m. Thegreatest bleaching mortality occurred at Islas del Rosario and Islas San Bernardo, mainlyamong colonies of Acropora palmata, A. cervicornis, Diploria labyrinthiformis and Milleporaalcicornis. Extensive patches (> 100 m 2 ) of recently dead A. palmata and A. cervicornis wereobserved. Subsequent mortality was also observed in tagged colonies that were re-examinedtwo months after the peak of bleaching; some of these colonies were greater than 50 cm indiameter. However, most reefs that suffered bleaching had recovered within 6 months of theonset of the event.IS COMPETITION FOR SPACE BETWEEN THE ENCRUSTINGEXCAVATING SPONGE CLIONA TENUIS AND CORALSINFLUENCED BY HIGHER TEMPERATURES?The rate of lateral overgrowth by excavating sponges was measured to see whetherheat stress in corals may make them more susceptible to encroachment. There wasno change in rate of lateral spread of the sponge Cliona tenuis growing over colonies ofthe corals Diploria strigosa and Siderastrea siderea at 5-6 m depths between June 2001and July 2002, when there was no unusual warming, and in August 2004 and September2005, which coincided with significant warming. Sponge spreading on S. siderea remainedconstant, but was more variable on D. strigosa, irrespective of whether there was partialor total bleaching of the corals. These experiments indicate that there may be differentialsusceptibility to excessive warming within and between coral species and perhapsbetween individual sponges (from Juan Carlos Márquez, juancmarquezh@gmail.com;Sven Zea, szea@invemar.org.co; and Mateo López-Victoria, Mateo.Lopez-Victoria@bio.uni-giessen).109
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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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The 2005 Bleaching Event: Coral-Lis
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