‘Coral lab’ offers acidity insight (videos)

Five metres under the blue waters of the Red Sea in Eilat, Israel, we’re examining a long steel table arrayed like a plant nursery with ranks of near-identical specimens. They’re not plants, they’re corals, which are being cultivated for experiments into ocean acidification.

The specimens are taken to one of the world’s most desirable science laboratories – the Interuniversity Institute for Marine Science, located right on the beach at Eilat.

There, scientists are reaching worrying conclusions, particularly for the hundreds of millions of people who rely on fish that depend on coral reefs.

The project is led by a lean triathlete, Dr Maoz Fine.

He started by measuring the growth rate of corals at a pH of 7.9, which is about the same level that the world’s oceans, on average, are expected to reach by the end of the century.

To his surprise, the corals – which produce alkaline shells – were only slightly affected by the decrease in alkalinity during the one-year experiment.

He lowered the water’s pH to 7.6, which is roughly equivalent to about 1,500 parts per million of CO2 in the atmosphere.

The unpublished experiment is controversial because it creates conditions much worse than even the most pessimistic forecast.

Dr Fine defends it because he says we need to find as soon as possible whether different corals will react differently to higher acidity by pushing the limits of coral physiology to extreme.

He was amazed to find that the fast-growing branching corals (Stylophora pistillata) did well even under this low pH.

But the slow-growing corals (Porites), which form the bedrock of the reefs, were demonstrably harmed.

Far more alarming is the experiment on a humble calcareous algae, which looks like pink paint on a rock.

This algae plays a vital role in cementing reefs together. But it cannot survive the pH levels of 8.0 predicted before the end of the century, possibly as early as 2050.

That means the reefs are likely to begin to crumble.

“Corals will continue to exist,” Dr Fine says, “but the reefs will be greatly changed from what we know now and their biodiversity will be dramatically reduced.

“This will make them much more vulnerable to other catastrophic events, like bleaching.

“We are piling problems upon each other.”

Roger Harrabin, BBC News, 12 March 2009. Full article and videos.

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