Geography Assistant Professor Brendan Roark, who just recently joined the faculty in the College of Geosciences, presented research at the American Association for the Advancement of Science (AAAS) Annual Meeting in Boston last week. He and his colleagues presented their new research showing that deep-sea corals growing off Hawaii are much older than previously thought—some as old as 4,000 years.

Using radiocarbon dating and samples of coral collected from the ocean floor by the submersible vehicles of the Hawaii Undersea Research Laboratory, the researchers from Stanford and Lawrence Livermore National Laboratory have found that Gerardia, 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-water black coral Leiopathes glaberrima. Another tree-like skeleton, it has life spans in excess of 4000 years.

“Deep-sea corals can be spectacularly long-lived, which makes them critical contributors to our efforts to understand the past,” said Roark, a paleoceanographer who did his research while a post-doctoral fellow at Stanford University.

“These 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 global warming. The coral might further our understanding, for example, of how the oceans absorb carbon dioxide from the atmosphere.”

Many corals grow their skeletons in a manner similar to tree trunks, laying down growth rings that become historical archives of the water conditions over time. Analyzing the chemical composition of these layers allows researchers to trace changes in ocean circulation and temperature over hundreds to thousands of years. Such historical reconstructions are critical for understanding how climate change occurred in the past and for making predictions about the future.

Roark’s findings on growth rates and longevity also challenge the adequacy of the age models upon which the management of deep-sea coral species are based. “Growth rates have been overestimated by an order of magnitude in some fisheries management plans. Our new understanding of the great longevity of some of these species strongly suggests the need for more rigorous measures to ensure their populations are adequately protected,” Roark said. “They are placed in jeopardy not only by coral harvesters but also by sea trawling and long line fishing. Clearly a different frame of mind is needed,” he said. “It’s not a renewable resource.”

Roark plans to continue this research at Texas A&M. For more information visit the Geography Department website at http://geography.tamu.edu/.