Recuperação dos corais / Coral recovery

Seções da Grande Barreira de Corais da Austrália se recuperaram de maneira surpreendente de um evento devastador de branqueamento (perda de uma substância simbiótica, com a exposição do esqueleto branco), ocorrido há três anos, dizem cientistas marinhos.

Em 2006, altas temperaturas do mar causaram o branqueamento de várias estruturas de corais nas Ilhas Keppel. O tsunami de 2004 foi prejudicial aos corais, mas nada se compara à ação do homem, com o turismo, além das emissões de CO2, que causam a acidificação do oceanos.

Um quinto dos corais em todo o mundo já morreu ou foi destruído, e a tendência é de os danos crescerem.

Damaged Barrier Reef coral makes 'spectacular' recovery

Lucky combination of circumstances means corals have unexpectedly grown back within a year.

Sections of coral reef in Australia's Great Barrier Reef have made a "spectacular" recovery from a devastating bleaching event three years ago, marine scientists say.

In 2006, high sea temperatures caused severe coral bleaching in the Keppell Islands.

Coral bleaching occurs in higher sea temperatures when the coral lose the symbiotic algae they need to survive. The reefs then lose their colour and become more susceptible to death from starvation or disease.

But the ecosystems are under threat worldwide from overfishing, coastal development and runoff from the land, and in some areas, tourism impacts. Natural disasters such as the earthquake that triggered the Indian Ocean tsunami in 2004 have also caused reef loss. Climate change poses the biggest threat to reefs however, as emissions of carbon dioxide make seawater increasingly acidic.

Last year a study showed that one-fifth of the world's coral reefs have died or been destroyed and the remainder are increasingly vulnerable to the effects of climate change.

The Global Coral Reef Monitoring Network says many surviving reefs could be lost over the coming decades as CO2 emissions continue to increase.