A lab just off Florida's Miami River has become the base for an unusual lifesaving operation.

A group of scientists there is on an urgent mission to save as many corals as it can before the marine creatures are destroyed as part of an underwater excavation of Miami's shipping channel. The channel — set to be dredged and deepened on Saturday — is home to a thriving coral reef.

Coral reefs are protected throughout the Atlantic and Caribbean. Even scientists aren't allowed to take coral from the wild without special permits. But in Biscayne Bay, Colin Foord and a small group of marine researchers are racing the clock.

"They're calling these 'corals of opportunity' — essentially, corals that are living in a place that is slated to be destroyed for a government infrastructure project," Foord says. "They basically allowed us to go in at the last minute and rescue all of the smaller corals that were left behind."

Foord's company, Coral Morphologic, researches Florida's coral reefs and documents them through film and multimedia. Working under a state permit, he and other divers are transplanting the corals they save to an artificial reef a few miles away.

On a small boat, Foord and three other researchers motor down the Miami River into Biscayne Bay, slowing at one point to make way for a manatee. This is a working port, with massive freighters and cruise ships coming and going. Foord says it also turns out to be good habitat for coral.

"We're finding brain coral. We're finding boulder corals, the mountainous star coral. We're finding about four or five species of corals that just this past year were proposed to be listed on the endangered species list. And they're all growing out there," he says.

The boat, headed 2 miles out into the bay, speeds past huge cranes unloading container ships at the port, and condos and sunbathers on Miami Beach.

In the middle of the channel here on the previous day, divers spotted some large corals. They've come back to rescue them.

As Foord maneuvers the boat, port officials pull up in another boat to warn the crew that a freighter is coming, headed right through the spot where they're diving. They're told they have 20 minutes.

"OK, that's all we need. I have corals from yesterday that they had to abandon. We're just going to get the corals, and we're going to get out," Foord says.

As the boat bobs in a choppy 3-foot sea, Sam May, a junior at the University of Miami, pulls on his wet suit and diving gear.

"The depth is not what's exceptionally challenging about here. It's the fact that it's such a busy waterway," he says. "We have to time it correctly around the currents, otherwise we have this huge 5- to 6-knot current that flows through."

May and another diver go into the water with big baskets attached to buoys. Within a few minutes, Foord and another crew member haul in the baskets. Inside are 30-pound corals nearly 2 feet in diameter.

"Whew. We should not be destroying corals that are that huge," Foord says.

With a freighter bearing down, Foord begins motoring the boat back to the lab. May says these are some of the largest corals he's handled — and there are still more to be rescued.

"We got to the end of the dive and some of the biggest ones are still down there, which is a huge shame," May says.

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