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Bringing Home the Big Guy with Floats and a Four-ton Winch

She found it on a clear spring afternoon in May 2001. Just by looking, she knew that the massive coral would be perfect for her research.

For ten days, Anne Cohen and two colleagues had donned scuba gear and combed the reefs two miles southeast of Bermuda for the best specimen for reconstructing centuries of climate conditions.

“It had a nice, big, round shape, like a mushroom,” said Cohen about the 1,500-pound brain coral she affectionately calls “the big guy.” “I estimated that this one was a few hundred years old.”

She chose the big coral not only because of its size and likely age, but also because of its condition and location. The venerable coral’s days seemed numbered: its stubby stem was eroded, making a collapse imminent. And it was somewhat isolated on the reef, so the researchers could avoid interfering with other corals in the area.

But hauling the massive coral from 50 feet below the surface proved tricky. Cohen and colleagues Robbie Smith and Graham Webster from the Bermuda Biological Station for Research (BBSR) had to hire a local salvage boat with a four-ton winch to haul it in. They labored underwater to secure the coral with harnesses and a float and to score and weaken the stalk with handsaws.

After hours of cutting, the coral broke free and quickly rose to the surface, despite its staggering weight. “It must have taken about 10 seconds,” Cohen recalled. “I didn’t even capture it on the underwater video camera. It all happened too fast, and I was more concerned with getting out of ---
the way.”

Back on shore, a curious crowd gathered to peer at the rough, maze-like surface of the coral skeleton. A forklift hauled it from the salvage boat to the dock, and a truck carried it to BBSR for packing and shipment. On earlier expeditions, Cohen had her prized specimens held up by US Customs agents. But this time, the coral had a quick and safe passage to Woods Hole.

Then her research hit an unexpected wall. When Cohen tried to slice into the skeleton, “the saw just disintegrated,” she said. “The coral ate the chainsaw.” It took several months to locate someone who could help.

Cohen finally found a quarry that routinely cuts large slabs of marble for buildings, foundations, and statues. Like marble, coral is just another form of limestone or calcium carbonate. Still, the quarry saws had never sunk their teeth into such an unusual rock, so the workers gathered around Cohen’s specimen with great interest.

They set up a commercial saw, and after an hour or so,sliced a cross-section of the coral that she could X-ray. The Bermuda brain coral turned out to have been born about seven years before George Washington, dating to 1725.

Today, as Cohen digs into that long climate history book, she is also working with colleagues from Boston University to develop ultrasound-imaging equipment to study corals underwater. In the future, she hopes to collect skeletal data from living corals without having to cut them down and haul them back to the lab.

“We hope to go right in the water with the ultrasound equipment so we don’t have to bring the coral out of the water,” she says. “We could look at several corals on the same dive, allowing the coral to keep growing and saving us the trouble of having to cut it up.”

Last updated: August 14, 2007