Despite dire predictions about the impact of climate change on Australia's iconic Great Barrier Reef, researchers have found that badly-damaged coral has managed to repair itself. Scientists say, although this is a heartening discovery, the threat of global warming to the world's largest coral system has not diminished.
Scientists have warned that the Great Barrier Reef - which stretches for more than 2,500 kilometers down Australia's northeast coast - is likely to bear the brunt of warmer ocean temperatures.
A major concern has been the bleaching of coral, where the sensitive marine organisms wither under environmental stress caused by increased water temperature, pollution or sedimentation.
Unexpected discovery brings good news
An unexpected discovery at the southern end of the reef has provided some rare good news for researchers.
Researchers found that coral in the Keppel Islands off Queensland, which was damaged by bleaching in 2006 and then smothered by seaweed that overgrew the reef, has managed to repair itself.
Laurence McCook from the Great Barrier Reef Marine Park Authority says the sudden disappearance of that stifling band of seaweed helped spark the recovery.
"Although the reef was covered in this massive bloom of a particular seaweed, that seaweed experienced a quite spectacular, unusual die-back," he explained. "Now, that gave the corals a kind of a second chance, if you like. And, the second factor was that the corals really took that chance, showing spectacular growth and in particular re-growth from surviving fragments of coral tissue."
Pollution under control
Another key factor was the pristine condition of the sea, with pollution now controlled by restrictions on fishing and controlling the runoff of soil and pesticides from farms on the mainland.
Experts say to see reefs bounce back from mass coral bleaching in less than a decade is highly unusual.
Like other coral systems, the Great Barrier Reef is facing a range of environmental threats. Scientists say their capacity to recovery from damage inflicted by warmer waters, for example, will be critical to its future health.
The Great Barrier Reef is one of Australia's premier tourist attractions. It covers an area bigger than Britain and is the largest living structure on earth and the only one visible from space.