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Carbon Dioxide is Killing Cold-Water Reefs

The effect of carbon dioxide on cold-water corals is much like osteoporosis in humans.


By Philip Bethge

The greenhouse gas carbon dioxide is acidifying the oceans. The first victims could be cold-water coral, which are believed to populate the edges of all continental shelves. Another endangered species is the plankton in the open oceans -- the basic building block of the marine food chain.

The Skagerrak strait is a gray body of water in March. But under the waves, at a depth of 100 meters (328 feet), an underwater Garden of Eden is growing.

Whitish hard corals glint in the beam of the headlights of the Jago, a research submersible. Rosefish and bibs flit by. The coral reefs are home to sea stars, sea urchins, sea squirts, long-legged crabs and yellowish sponges.

Ulf Riebesell sits directly within the Jago's viewing dome, in front of pilot Jürgen Schauer, so that he can study the reef more closely. After a three-hour dive, Riebesell, a researcher at the Leibniz Institute of Marine Sciences (IFM-Geomar) at the University of Kiel in the German Baltic Sea city, is completely captivated. "Some of the underground mountains down there are completely covered with magnificent coral branches," raves Riebesell. "The view is simply overwhelming."

Riebesell and his fellow researchers have spent the last few weeks visiting this fairytale-like coral garden in the region where the North Sea and the Baltic Sea meet, only a few nautical miles off the coast of Norway. The reason for their expedition on board the Alkor, a research ship, is that the habitat on the sea floor, which has hardly been studied, is deeply imperilled.

"Cold-water corals could be the first organisms to fall victim to the acidification of the oceans," says Riebesell, whose dire prediction is supported by a study that appeared earlier this week in the professional journal Frontiers in Ecology and the Environment -- a publication of the Ecological Society of America. In the study (link is in PDF format), experts working with John Guinotte at the Marine Conservation Biology Institute in Bellevue, Washington report that 70 percent of the current habitat of coral branches may no longer be suitable for these organisms by as early as the end of this century.

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