coral wins with change …

cold water coral imageCredit: S. Ross et al., UNCW

We already know that pH varies naturally across the oceans of the world. In some sites, it varies more in a single day than global oceans are likely to face in a century.

But cold water corals live in deep water, are slow growing, and hard to study.

Six years ago, experts in cold water corals were telling us how they would be likely to fall victim to ocean acidification first, and that they believed this for good reasons but with little experimental data. But about a year ago data came out (by one of those same experts) showing that rather than being the badly affected, cold water corals adapted to effectively very high levels of CO2 and possibly even increased their calcification rates. Eight days after the pH was changed suddenly, the corals did worse. But when the experiment was continued for six months, the results turned right around. The researchers pointed out how useful longer studies are: “This is the first evidence of successful acclimation in a coral species to ocean acidification, emphasizing the general need for long-term incubations”. The paper is called “Acclimation to ocean acidification during long-term CO2 exposure in the cold-water coral Lophelia pertusa.” The pH fell as low as 7.75 in the long term study (from the normal pH of about 8.1).

It’s highly unlikely the atmospheric levels of CO2 will reach 1,000 ppm in the next couple of centuries, but if they did, it appears that at least one major and widespread species of cold water coral can adapt within six months. Co2 feeds plant life above the water, and atmospheric levels were much higher during the time that corals evolved. That doesn’t guarantee anything, but suggests scientists could have been more cautious in predicting a disaster when they didn’t have the data.

cold water corals and ocean acidificationIn short term studies the growth of a major cold water coral slows as CO2 levels rise

The results:

In 6 month studies, even very high levels of CO2 were not detrimental to cold water corals. Indeed the corals appeared to grow faster.

In 2006 experts thought Cold Water Corals would be some of the first to suffer

Keep reading  →

About Tom Harley

Amateur ecologist and horticulturalist and CEO of Kimberley Environmental Horticulture Inc. (Tom Harley)
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