By Ian Williams, NBC News correspondent

Editor's note: Ian Williams's report airs tonight on the broadcast. Watch a preview here.

Phi Phi Islands, Thailand--Andrew Hewett fished a small fragment of coral from a bucket of water and held it between his fingers.

"It's been knocked off, broken by an anchor or somebody standing on it," he said, explaining that while the devastating 2004 tsunami caused a lot of damage to the area's coral reefs, the bigger threat to the reefs comes not from nature, but from man.

He then showed how to drill a small hole in the fragment and attach it to a metal rack (see photo, right). Moments later, a production line was up and running on the deck of the dive boat, students threading hundreds of fragments and pulling them tightly to the racks.

"If I can't pull it off, then a fish certainly can't," said Nichole Niewald, a biology major at the University of Missouri.

The fragments had been collected from the ocean floor, the remains of a badly damaged reef.

"Day by day people are walking on the reef, not paying enough attention, and not treating the coral like the animals they actually are," said Steve Monson, who studies food science at Mizzou.

Eighteen students and staff traveled from Missouri to the Phi Phi islands in Thailand to take part in a pioneering coral rehabilitation project. Their trip was organized by Bob Sites, Professor of Entomology at Mizzou's Division of Plant Sciences, a regular visitor to the Kingdom. It's the second year he's brought students to the coral project. All the students are from Mizzou's College of Agriculture, Food and Natural Resources. (Photo, left: NBC cameraman Kyle Eppler videotapes as Andrew Hewett and the students examine coral fragments.)

"Getting some college students from the central U.S., where there are no reefs, to come here and study reefs, is a very important thing," he told me. "It's hands-on conservation."

Once the racks were full, the students -- most of them recently qualified divers -- donned their dive suits and tanks and took the plunge, carrying the racks down to a coral nursery a few yards beneath the surface. The nursery is a suspended platform, anchored to the seabed. The fragments were left here to grow for ten months, away from the sediment.

"It's very much like a greenhouse. First getting it to grow, then transplanting it back to the real thing," said Allison Clarke, a major in Agricultural journalism.

"The coral's going to grow now, without anybody bothering it," said Niewald.

The project began as reef clean-up after the tsunami, which killed more than seven hundred people in the Phi Phi islands alone. In the weeks that followed, all manner of rubbish, from beds to air conditioners, was pulled off the reef by volunteer divers organized by Hewett, who runs an eco-tourism company called the Adventure Club.
Hewett, his wife, and two young children narrowly escaped, running to high ground, when the wave swept across the island.

He now runs the rehabilitation project with marine biologists from the Phuket Marine Biological Centre, welcoming young volunteers, like the Mizzou students.

"The tsunami did some damage, but not nearly as much as man," said Mizzou's Sites. Perhaps five to 10 percent was destroyed by the force of the wave.

The Phi Phi Islands, comprising giant limestone cliffs, as well as stunning beaches, is slowly recovering from the trauma of the tsunami, though redevelopment has been slowed by disputes over land ownership. The seas around the Phi Phis still contain some of the most pristine reefs in Asia, but they are increasingly under threat - with careless divers and snorkelers, as well as dive and tour and fishing boats taking a heavy toll.

The coral project now concentrates on reef rehabilitation and education. Once the students had placed the new racks in the nursery, they took racks from last year, the coral showing healthy growth, for replanting on a damaged reef (see photo, left). They did this by finding small natural holes, or by drilling holes, into which to insert the stem of the coral, which they hope will bond with the host coral. Once the students have returned to the U.S., the local marine biologists will monitor the growth.

Many corals take decades to grow; others are quicker. The coral fragments the students worked with had grown around half an inch in a year.

"Some grow so slowly that if you break off an inch, that could be a decade of growth," said Kizzi Roberts, a Animal Science major.

The project is also trying to create an entire reef of its own -- an artificial one, made from giant concrete blocks, some thirty feet below the surface. They hope it will provide an alternative dive site, to take pressure from tourism off natural coral formations. When I dived with the students, the coral was showing healthy growth, and curious marine life was moving in. A pair of clown fish had taken up residence.

"Seeing the dead coral, then planting the coral, its kinda neat to see, bringing it back," said Dustin Warner, who studies Business Management.

The Mizzou students certainly felt they were making a difference for the marine environment: "Getting down there and planting the coral, you really feel you are actually doing something," said Allison Clarke, who looked on with deep concern as a bunch of snorkelers splashed around in an area close by. "I'm feeling protective," she said. "We've put a lot of work in, and I wouldn't want to see them stamping all over it."