Stanford researchers say living corals thousands of years old hold clues to past clima...( Using radiocarbon dating and samples ...)

Using radiocarbon dating and samples of deep-sea corals snipped from the floor of the Pacific Ocean by a submersible, researchers from Stanford and Lawrence Livermore National Laboratory have discovered that deep-sea corals growing off Hawaii are much older than previously thoughtsome as old as 4,000 years.

The surprise finding is important in two areas, says Stanfords Brendan Roark, a postdoctoral fellow of Professor Robert Dunbar in the Department of Geological and Environmental Sciences. Roark will speak on the research Thursday and Friday in Boston at the annual meeting of the American Association for the Advancement of Science (AAAS).

First, the finding suggests that harvesting of the oldest coral for jewelry should be banned by federal and local officials, he said. The long-lived corals grow so slowly that any level of harvesting is unsustainable; they take so long to grow that they simply cant replace themselves fast enough to survive even minimal harvesting.

Second, a 4,000-year-old coral, having stood in the same place in the Pacific Ocean and imbibed of the waters for so long, holds within its skeleton clues about the conditions of the ocean over many centuries. Ancient coral may turn out to be the archives of the ocean, Roark said, a unique reference library of past climate changes that could prove useful in understanding future climate change.

The coral might further our understanding, for example, of how the oceans absorb carbon dioxide from the atmosphere.

These organisms are the equivalent of the bristlecone pine in the deep ocean, he said. They are placed in jeopardy not only by coral harvesters but also by deep-sea trawling and long-line fishing. Clearly a different frame of mind is needed, he said. Its not a renewable resource.

Roark and his associates found that Gerardia, commonly known as gold coral, can live for at least 2,700 years. It grows in tree-like fashion to several meters in height. Even older is the deep-wat
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