Global warming may have damaged coral reefs forever

Miles of unblemished coral reefs have been turned to slime-covered rubble because of rising sea temperatures caused by global warming.

A study into the extensive bleaching of the Seychelles corals in 1998 has found that these Indian Ocean reefs failed to recover, with many of them crumbling to broken fragments.

Scientists said the findings showed that rising global sea temperatures could have a more devastating impact on the world's tropical corals than previously thought.

"Some of the reefs have collapsed to almost mobile beds of rubble. They are no longer solid structures and some have been overgrown with fleshy green mats of algae," said Nicholas Graham, a coral ecologist at the University of Newcastle, reports Independent.

According to Environment News Service, when coral reefs are bleached out, they may never recover, according to the first report on the long-term impact of a 1998 global warming event in the Indian Ocean that damaged the reefs of the Seychelles' Inner Islands. Fish species that depended on the damaged reefs are already locally extinct, the study found.

From autumn 1997 to spring 1998 the Indian Ocean, and many of the world's other tropical oceans, experienced a rise in sea water temperature. In the Indian Ocean this was attributed to an El Nino Southern Oscillation event that scientists view as part of an overall pattern of global warming.

Situated in the Indian Ocean four degrees south of the equator and a thousand miles off the east coast of Africa, the Seychelles are a group of some 115 islands scattered across 500,000 square miles. The Inner Islands in the northern part of the archipelago are one of three main Seychelles island groups.

During the 1997-1998 autumn, winter and spring, branching coral species on the reefs surrounding the Seychelles inner islands bleached and died, particularly corals such as staghorn, elkhorn and table corals.

The research showed the 1998 event's main long-term impacts are down to the damaged reefs being largely unable to reseed and recover and the collapse of the reefs removed food and shelter from predators for a large and diverse amount of marine life - in 2005 average coral cover in the area surveyed was just 7.5 percent.

"We have shown there has been very little recovery in the reef system of the inner Seychelles islands for seven years after the 1998 coral bleaching event," lead researcher Nick Graham of Newcastle University said.

"Reefs can sometimes recover after disturbances, but we have shown that after severe bleaching events, collapse in the physical structure of the reef results in profound impacts on other organisms in the ecosystem and greatly impedes the likelihood of recovery," he added, informs Xinhua.


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