Reefs more resistant to acidification: researchers

New research indicates coral reefs are more resistant to ocean acidification than first thought.

Scientists have been concerned that reefs are threatened when atmospheric carbon levels rise and ocean acidity increases.

But Australian National University research on the Great Barrier Reef suggests the structure of the reefs is stronger than previously thought.

The reports’ lead author, Merinda Nash, has told Radio Australia’s Pacific Beat program they have discovered a strong mineral called dolomite in the algae which helps bind reefs together, meaning the structure is less vulnerable to acidity than expected.

“What’s important about that is that prior to our discovery, everybody had thought that this coralline algae was made up of magnesium that was was thought to be, and is, very susceptible to dissolution,” she said.

“So there was a lot of concern that the coralline algae, which plays a key role in building the reef and binding corals together, that this would be the first thing to dissolve as CO2 went up and that that would impact the reef structure.

“We found that this presence of dolomite actually reduced the dissolution rate significantly, to about one tenth the rate of the algae without the dolomite, so that’s quite good news.”

The latest research, published in Nature: Climate Change, found the algae has a rate of dissolution six to 10 times lower than coral’s.

Ms Nash says while that’s good news for the algae, the coral itself still appears to be at risk.

“The best analogy that I can give is that the algae that we look at is like the cement in the house made of bricks and the coral are the bricks.

“So if you could imagine a house that had bricks and no cement – it wouldn’t be a very strong structure.

“So the coralline algae with dolomite look to be quite resistant, but what happens to the corals will be a different story.”

Ms Nash says while some research indicates an increasing resistance in coral, and certain species which are able to adapt, it looks like corals are still going to be impacted by the rising temperature and acidity.

But she says the research is good news for coastal communities which rely on coral reefs for protection.

“What is really good about this is for a lot of the Pacific Islands that are coral atolls, that face high energy waves all the time, a lot of those islands are actually protected by ridges that are built just about entirely out of coralline algae in the top couple of metres,” she said.

“Where the waves are strongest is where the algae with the dolomite loves to grow, so it has a really critical role protecting shorelines and human communities on the shore from the worst affects of the high wave energy.”

Australia Network News, 11 December 2012. Article.

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