Corals thousands of years old hold clues to past climate changes

Washington, Feb 15 : A new research has discovered that deep-sea corals growing off Hawaii are much older than previously thought and might hold clues about the conditions of the ocean and climate changes over many centuries.

The research was carried out by scientists from Stanford and Lawrence Livermore National Laboratory using radiocarbon dating and samples of deep-sea corals snipped from the floor of the Pacific Ocean by a submersible.

The coral samples were collected in waters as deep as 1,500 feet at the Makapu'u deep-sea coral bed off the southeast coast of Oahu, Hawaii. For collecting the samples, researchers went down in the Hawai Undersea Research Laboratory's submersibles, Pisces IV and V.

According to Brendan Roark, a postdoctoral fellow of Professor Robert Dunbar in the Department of Geological and Environmental Sciences, the surprise finding is important in two areas.

First, the finding suggests that federal and local officials should ban harvesting of the oldest coral for jewelry.

"The long-lived corals grow so slowly that any level of harvesting is unsustainable; they take so long to grow that they simply can't replace themselves fast enough to survive even minimal harvesting," said Roark.

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, a unique reference library of past climate changes that could prove useful in understanding future climate change," said Roark.

The preliminary results suggest the possibility of reconstructing subsurface temperature variability and changes in ocean circulation.

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

ANI