Status of Coral Reefs of the World 2000

Status of Coral Reefs of the World: 2000
considerable degradation of coral reefs in Colombia for the last few centuries. During the
17 th century, Spanish colonists dug the Canal del Dique, changing the Magdalena River to
discharge into the Bahía de Cartagena, and turning the bay to an estuary, thereby eliminating
extensive coral communities. Additional branches of the Canal del Dique have been
opened recently to the Bahía de Barbacoas, resulting in turbid waters and eutrophication
that have damaged the coral reefs of the nearby Islas del Rosario. Accelerated damage to
coral reefs due to urban and industrial development was also reported on the central coast
of Venezuela (Puerto Francés-Carenero), where more than 80% of the associated
invertebrate species have disappeared since the mid 1980s.
CURRENT AND POTENTIAL CLIMATE CHANGE IMPACTS
The impacts of climate change have not been properly assessed in the region, although
there has been limited data collection on the occurrence of coral bleaching events.
Bleaching events were first recorded in the region during the first half of the 1980s.
Bleaching appears to have increased in frequency but not severity throughout the 1990s.
All bleaching events coincided with elevated sea surface temperatures, illustrating a
possible correlation with global climate change impacts. The most damaging bleaching
episode was along the Pacific coast during a severe ENSO (El Niño Southern Oscillation)
event in 1982/83 with coral mortality of 50-100% in most reefs. There was a second strong
ENSO event on the Pacific side in 1997/98, but the level of coral bleaching was moderate
and resultant mortality was low. On the Caribbean side, the most severe bleaching event
was also in 1982/83, with high levels of coral mortality at several localities, but unfortunately
this event was poorly documented. Mild bleaching occurred in 1997/98 at several
Caribbean and Atlantic localities, with less than 10% of the corals bleached in most cases
and insignificant mortality. As global warming is predicted to increase, and based on the
recurring patterns of recent bleaching in the region during the last two decades, it is
predicted that coral bleaching will become a more frequent event during the next decade;
although the level of bleaching and related mortality during each episode will probably be
low. However, the long-term negatives impact of these recurrent bleaching events may be
high if the increased frequency counteracts natural recovery capacity of corals.
Bleaching in Region 1982/3 1987 1990 1992 1993/4 1995 1997/8 1998 1999
Costa Rica - Caribbean Severe Mild Mild
Costa Rica - Pacific Severe Interm Mild Mild
Panamá - Caribbean Unkn Mild Mild
Panamá - Pacific Severe Mild Mild Mild
Colombia - Caribbean Severe Interm Mild Mild Mild Mild
Colombia - Pacific Severe Mild
Venezuela - Caribbean Unkn Mild Mild
Brazil - Atlantic Mild Mild
The incidence of coral bleaching events appears to be increasing over the last two decades in the
coasts of southern tropical America. The relative severity of those events was: Mild: 50% mortality, and Unknown (Unkn)
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