Thursday, February 16, 2012

Can cold-water corals adapt to climate change?

Geomar, the Helmholtz Center for Ocean Research Kiel (Germany): Are cold-water corals able to withstand ocean acidification? A long-term experiment carried out at the German Helmholtz Centre for Ocean Research Kiel (GEOMAR) showed, that the species Lophelia pertusa continues growth when exposed to ocean acidification. This unexpected finding is now published by GEOMAR scientists in “Global Change Biology”. In a new series of experiments, they will analyse how the corals react to combined changes in carbon dioxide concentration, temperature and food availability as projected to occur during the next decades to centuries.

By absorbing about a third of man-made carbon dioxide (CO2), the ocean decelerates global warming. However, when dissolved in seawater, CO2 reacts to produce carbonic acid, causing seawater pH to decrease. It also diminishes the concentration of carbonate ions, thereby putting organisms forming their shells and skeletons from calcium carbonate at risk. Apart from plankton, algae, mussels and snails, stony corals are among those particularly endangered: Their skeletons consist of aragonite, the most soluble form of calcium carbonate.

“Model calculations indicate that if CO2-emissions continue at current rates, more than 70 percent of cold-water coral reefs known today will be exposed to conditions corrosive for calcium carbonate by the end of this century. It seemed obvious, therefore, that these corals will be among the first to suffer from the effects of ocean acidification”, explains Ulf Riebesell, Professor of Biological Oceanography at GEOMAR. “But our results do not support this”, adds the Kiel marine biologist Dr. Armin Form. “For the first time ever, we showed that the globally widespread species Lophelia pertusa keeps growing even in corrosive waters if given the time to adjust to the new conditions.” Armin Form and Ulf Riebesell now presented their results in the renowned journal Global Change Biology....

Sampling Lophelia pertusa with JAGO. Photos: JAGO-Team, GEOMAR, from the GEOMAR website

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