"Some coral grows like a tree; each year a complete layer with both a high and low-density skeletal calcium carbonate band is formed by the coral animal," says Dr. Lisa Greer, assistant professor of geosciences. "Not all corals create rings, but the massive corals like boulder star coral or pin cushion coral do."
Greer, and Dr. Peter Swart, professor at the Rosenstiel School of Marine and Atmospheric Science, University of Miami, looked at both modern and fossil corals to see if the calcium carbonate of the coral skeletons could shed light on the temperature and salinity of the tropical Atlantic Ocean.
"In contrast to research in the tropical Pacific, there have been few definitive studies utilizing proxy records within Atlantic coral skeletons to provide information on the climate dynamics in this region," Greer told attendees at the fall meeting of the American Geophysical Union today (Dec. 7) in San Francisco.
Information on the climate dynamics of the Atlantic is necessary as input to global and regional climate models. Not only are the current dynamic patterns important, but patterns from the past, which may differ from today, are important as well.
Greer uses a dental x-ray to locate the coral layers in a very thin slice taken from the core. In modern coral, she then counts down from the top to associate the layers with actual years. The sample she reported on was taken in 1994 and went back to 1935. Once the layers are located, Greer takes very small samples of the coral in a line running up the coral section. She averages about 22 samples per year covering the 59-year span.