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CT Finds Hidden Evidence Of Coral Decline

July 22, 2010
Written by: , Filed in: Diagnostic Imaging
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Once again, CT turns out to be a really handy—and versatile—technology. In the latest “who would have thought?” use, scientists at Woods Hole Oceanographic Institution (WHOI) in Massachusetts modified CT software to test the health of coral in the Red Sea.

The investigators specifically looked at Diploastrea heliopora, a major Red Sea species. “These corals looked healthy,” said co-lead investigator Anne L. Cohen, PhD, a WHOI research specialist. However, “The CT scans reveal that these corals have actually been under chronic stress for the last 10 years, and that the rates of growth were the lowest in 2008,” which was the final year of the study.

Dr. Cohen was quoted in a WHOI news release, which, oddly, now seems unavailable on the WHOI Web site but was itself quoted by ScienceDaily. The research was published in the July 16 issue of Science.

The researchers said that skeletal growth of the coral had declined by 30 percent over 10 years and that the coral “could cease growing altogether by 2070.” They blamed global warming. Summer Red Sea surface temperatures, they said, have remained elevated by about 1.5 degrees Celsius over the decade, ruling out El Nino (a natural warming trend that normally lasts a year or two) or some other short-term phenomenon.

The coral, though outwardly healthy looking, showed an abrupt and continuing drop in skeletal growth after 1998. The researchers credited CT for allowing them to detect the growth changes. Scientists have previously used X-rays to study coral, said Neal E. Cantin, PhD, a WHOI postdoctoral investigator who was the study’s other co-lead researcher. X-ray analysis usually requires cutting into the coral skeleton.

“The biggest advantage we have over X-ray is that we can scan intact cores without cutting the core into thin slices,” Dr. Cantin said. “Since corals do not grow in a straight line, when the core is cut, inevitably the growth axis will be lost from a thin cut.”

Dr. Cantin “took [CT scanning] to another level,” Dr. Cohen said. “What Neal really did was to adapt the imaging software, previously developed for bodies, specifically for our coral needs. This was an excruciatingly difficult task, but it certainly paid off. We could not have used conventional techniques on this coral. The skeletal architecture is too complicated.”

Related seminar: Computed Body Tomography: The Cutting Edge


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