Grief on the Reef

New Scientist

March 5, 2004

Sea-surface temperature chart showing Coral bleaching hot-spots

Australia’s Great Barrier Reef may be on the verge of a massive outbreak of coral bleaching caused by sea temperatures soaring for the third time in six years.

“The entire reef has been in a bleaching hotspot for the past month, and excessively hot water is still spreading and intensifying,” says Tom Goreau of the Global Coral Reef Alliance in Cambridge, MA who issued the first warnings of the last bleaching epidemic two years ago. The sea is currently up to 2°C warmer than normal.

Goreau predicts that this bleaching “will be the worst yet,” and will extend across the South Pacific to the Solomon Islands, Vanuatu and New Caledonia.

Bleaching occurs when hot water expels the algae that live in coral and give it its color. Usually, the algae will return but persistent bleaching can banish them forever, killing the coral.

Goreau blames global warming for the high sea temperatures. “People often try to blame El Nino, but this is not even an El Nino year,” he says. In a report last week, the University of Queensland’s Centre for Marine Studies in Brisbane warned that warmer oceans could kill the Great Barrier Reef within 50 years.

The Great Barrier Reef Marine Park Authority has been accused in the past of playing down damage to the reefs to protect the tourist industry. But last week its website warned that the threat of coral bleaching in the region is currently rated as moderate to high.