Forget the doom: coral reefs found to be much more robust and resilient than alarmists claim

Hoagy is astounded.  Has his life's work of alarmism just fallen apart?

A WIDESPREAD belief that the world's coral reefs face a calamitous future due to climate change is proving less resilient than the natural wonders themselves.

Rising sea temperatures, storm damage and ocean acidification have grabbed the headlines as looming threats to reef survival.

But as each concern is more thoroughly investigated, scientists are finding nature better equipped to cope than they had imagined.

The latest research, published in Nature: Climate Change today, blows away the theory that reefs were doomed due to rising ocean acidification caused by the higher take-up of carbon dioxide in the seas.

Researchers have found a common coralline algae that grows at the leading edge of coral reefs is not nearly as susceptible to changing ph levels as coral because it contains high levels of dolomite.  In fact, the dolomite-laden algae has a rate of dissolution six to 10 times lower than coral's.

The good news is that dolomite-rich coralline algae is common in shallow coral reefs across the world.  "Our research suggests it is likely they will continue to provide protection for coral reef frameworks as carbon dioxide rises," the paper says.

Lead author Merinda Nash, a PhD candidate with the Australian research school of physics and engineering, says the phenomenon has been overlooked because research to date has been on coral, not coralline algae. "It is not very sexy so it has not got a lot of attention," she said.

"What the research demonstrates is there is a lot we have yet to understand about coral reefs."

This is a sentiment echoed by James Brown of the Kimberley Coral Research Station, who believes the hot water corals of the Kimberley coast hold a treasure trove of answers for marine biologists.

Mr Brown has questioned why the Kimberley coral reefs were thriving in water temperatures and at acidification levels well outside of the limits that conventional science said should be inhospitable for their survival.

"Measurements of dissolved carbon dioxide have shown levels of up to 50 parts per million compared with the average of 28 parts per million," Mr Brown said.  "This is the outer limit of what scientists had believed would be habitable for corals.  Water temperatures are also at the top end of what coral biologists say it is possible for corals to survive in.

"The more we find out about the Kimberley, the more it rewrites the book on coral biology."

Further counter-intuitive results on coral survival have come from an extended project on the Great Barrier Reef to measure the health of deep corals.

The Catlin Seaview Survey has found the damage to coral reefs is literally skin deep, with corals located in deeper water below even the worst impacted sites thriving and in pristine condition. The findings raise the possibility that damaged corals may have an increased opportunity for recovery by recruiting new corals both from adjoining reefs and those located immediately below.

The early findings from the survey have astounded the scientists involved, including Ove Hoegh-Guldberg, a leading global figure in raising concerns about crown of thorns starfish, coral bleaching and ocean acidification.

"The survey has shown that deeper reefs may be protected to an extent from some of the perils of climate-driven events such as mass coral bleaching and storms," he said. "These deeper corals may be important refuges if we get big changes in the shallows."

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