September 6, 2008
While Some Coral Reefs Have Recovered, Others Still Decline
Coral reefs in the Indo-Pacific Ocean have largely recovered from the devastating hot water the off, or "bleaching event," that killed up to 90 percent of corals on some reefs in 1998, researchers announced last month. Coral reef ecologist Gregor Hodgson of the Reef Check Foundation explained that 10 years later, recovery has occurred more quickly and more completely than expected. Caribbean reefs, however, are losing about three percent of living coral every four years due to a combination of human impacts. "When the devastating 1998 bleaching event occurred and the extent of dead coral was tallied, many scientists feared that the dead reefs would not recover and that the remaining live reefs could be killed if such intense bleaching events continued," Hodgson said.Although smaller bleaching events have occurred, the damaged reefs began to slowly recover. New larval corals settled and began to grow. Now some of these corals measure more than one meter in diameter and carpet the previously damaged reefs, such as in the Maldives.
In 2005, another large bleaching event occurred in the Caribbean; however, much less damage was recorded. Reef Check scientists believe that this is because the more vulnerable species, such as branching staghorn and elkhorn corals, were already decimated due to other factors in the 1980s. The remaining coral may be more resistant to being killed by bleaching.
In a related publication, Hodgson and coauthors assessed the conservation status of 845 reef-building coral species using the International Union for the Conservation of Nature's Red List criteria.
Of the 704 species examined, 231 are listed in the threatened categories, while 407 are in the threatened and near-threatened categories combined. The proportion of corals threatened with extinction has increased dramatically in recent decades and exceeds most terrestrial groups. If coral reefs collapse, this will lead to a large-scale loss of biodiversity and economic losses of nearly $400 billion per year, according to researchers.
"On the scale of a decade, Reef Check data show that coral reefs can recover following damage," said Hodgson. "Looking ahead several decades, however, a combination of line, its - global warming, seawater acidification and overfishing that is destabilizing coral reef ecosystems -raise the risk of extinction."
Copyright Compass Publications, Inc. Aug 2008
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