Australia's Barrier reef not as fragile as once thought

It has inbuilt recovery from damage mechanisms

About 100 coral reefs within the Great Barrier Reef have been identified as having particular resilience that may help corals recover from bleaching and other threats.

The hardy "robust source reefs" – about 112 in number or about 3 per cent of total coverage – were found to be in cooler, outer reefs.

Their location helped shield them from the recent back-to-back annual bleaching that had devastated corals, the Australian and British researchers found.

Their proximity to stronger ocean currents than inland reefs also meant their annual spawning events could disperse coral larvae over a large region, fostering recovery after bleaching or cyclones.

A third characteristic was a relative absence of crown-of-thorns starfish, lowering their susceptibility to that threat.
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Peter Mumby, one of the authors of the reef paper appearing on Wednesday in PLOS Biology, said a single coral spawning event from the robust sites could "almost reach half the reefs of the Great Barrier Reef".

"These sites are important ecologically, providing some of the backbone of the reef," said Professor Mumby, who is based at the University of Queensland's School of Biological Sciences.

"We are trying to uncover the natural life-support system of the reef, so we can then support it," he said, adding: "The reef is much better connected than we thought."

The importance of supporting natural recovery processes would likely increase in the future "as climate change reduces the average size of coral populations and the need for recolonisation becomes more frequent," the paper said.

But with most of the robust sites clustered off Mackay in the central-south region of the Great Barrier Reef, any relative resilience might be of little benefit to more distant regions, such as the northern end.

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