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Scientists exploring offshore canyons for Atlantic deep-sea corals

Seventy miles off Ocean City, scientists aboard the federal research vessel Henry B. Bigelow are exploring a lush underwater landscape that until recently few would have imagined — colorful corals clinging to the rocky slopes of deep-sea canyons.

On this and other research cruises, remotely guided submersible cameras have captured scenes of bubblegum corals, sea whips and more growing in the dark, hundreds to thousands of feet below the Atlantic Ocean's surface. Other smaller patches dot the ocean floor in shallower waters closer to shore. Cold-water relatives of the showy corals found in warm tropical seas, these also harbor a rich variety of fish, sponges and other marine life.

"The deep sea is not just this barren place — there's amazing things that live down there," said Martha Nizinski, a National Marine Fisheries Service zoologist leading the Bigelow's recent exploratory cruise off the Delmarva Peninsula.

On Monday, prompted by what researchers found in recent years, a federal fisheries council is expected to move toward protecting some or all of the coral-lined canyons along the eastern edge of the continental shelf, which one environmental group calls "hidden treasures" of the Mid-Atlantic.

"These are fragile and beautiful creatures in areas that are just beginning to be explored," said Joseph Gordon, manager of ocean conservation efforts in the Northeast for the Pew Charitable Trusts.

Depending on what the Mid-Atlantic Fishery Management Council decides, he said, it could establish the largest marine habitat protected area ever in the Atlantic — a stretch of ocean bottom as big as Maryland, Delaware and Pennsylvania combined.

It's a new frontier for science and for conservation. Only in the last several years have scientists realized how many corals can be found in the many "submarine" canyons carved into the eastern edge of the continental shelf, from the Gulf of Maine to Cape Hatteras.

"Even though they're right off some of the most populated areas of the United States, most of these canyons have never been explored," other than for some oil surveys in the 1980s, said Thomas Hourigan, chief scientist for deep-sea coral research with the National Oceanic and Atmospheric Administration.

Unlike their shallow-water cousins, the deep-sea corals don't depend on sunlight, as they have no algae growing on them and supplying them food. Instead, the deep-sea corals sustain themselves by trapping tiny organisms carried along in the ocean currents.

Relatively few deep-sea corals are the stony type that build reefs. Many tend to be smaller than the warm-water corals, though some commonly known as sea fans or whips can grow larger.

"Like shallow-water corals, they appear to be hot spots of diversity," Hourigan said, with anemones and sponges growing on them and "everything from crabs to starfishes to shrimp and all kinds of little critters" crawling over and under them.

Experts thought deep-sea corals existed only in scattered patches around the world. With better submersibles and remotely operated vehicles for exploring deep underwater, scientists have learned they are much more broadly distributed, some are hundreds and even thousands of years old, and they're habitat for many fish and other marine life.

"And that's really galvanized efforts, not just in the United States but internationally, to protect these habitats," Hourigan said.

Several years ago, Congress directed federal scientists to make a concentrated search for them in U.S. waters. There have been a series of cruises to probe the depths along the Pacific, Gulf and Atlantic coasts.

The mission of the NOAA vessel Bigelow during its 12-day cruise this month is to explore some of the canyons along the Mid-Atlantic coast. Nizinski said it's too early to say what they'll find. On previous explorations of the Baltimore, Norfolk and other major canyons, she and other scientists have seen many soft gorgonian corals in "fantastic colors,'' ranging from white to shades of yellow, gold, red, pink and orange, she said.

"I have to say we are excited about every dive that we do, because we're just not sure what we're going to find," Nizinski said.

Congress also gave the councils regulating fishing off the U.S. coasts the authority to protect them. The Mid-Atlantic council is the first to use that authority to consider broad-based protection for canyons.

The council, which meets Monday in Washington, is weighing whether to limit commercial fishing either across wide swaths of ocean bottom beyond a certain depth, or in more narrowly targeted zones around individual canyons. The biggest threat to the corals appears to be bottom trawling, in which fishing vessels haul nets across the ocean floor.

"Other places in the world, areas like this have been demolished," Pew's Gordon said.

If the most protective option under consideration is adopted, he said, it could safeguard roughly 37,000 square miles of ocean bottom.

Commercial fishing interests hope the council doesn't bar them from current fishing grounds.

The bulk of the world's catch of longfin squid comes from the Atlantic from Massachusetts to Virginia, according to NOAA. And the prime areas for catching squid are along the canyon rims, said Greg DiDomenico, president of Garden State Seafood Association, an industry group.

Fishermen avoid trawling in the canyons, DiDomenico said, because modern navigation and sonar technology enables them to make precise hauls near but not over the edges. Moreover, it could cost upward of $100,000 to replace nets and electronic gear snagged in the rugged terrain of the steep valleys.

"If we know there's hard and soft corals in the heads of the canyons, there's no way our gear is going to interact with those," he said. "Let the guys fish right next to [the edge] because they've been doing it for 30 years."

Conservation advocates want to "freeze the footprint" of current fishing activity, allowing it to continue but barring it from expanding or moving.

"Over the decades, intensively fished areas have extended farther from shore and deeper due to technological advancements and market demand," said Jay Odell,director of The Nature Conservancy's Mid-Atlantic marine program, "so protecting remnant intact coral habitat where nobody is fishing yet would be a big conservation win."

While protection may be on the way for the corals deep in the Mid-Atlantic canyons, scientists acknowledge they may be more extensive than that.

Monty Hawkins, longtime skipper of the party boat Morning Star, regularly takes groups out from Ocean City to fish over man-made and natural reefs 10 to 20 miles offshore, where the water is 70 feet to a little over 100 feet deep. Underwater video and photography show those reefs have growths of sea whips and bubblegum corals, Hawkins said. And they teem with fish, particularly black sea bass, he said.

"Very few people have any idea we have corals growing off the coast of Maryland," Hawkins said one day recently as he took out another fishing party.

The corals dot the bottom in waters that the federal government has put up for lease to develop offshore wind energy. Hawkins said he's hopeful regulators will ensure that the massive turbines aren't built atop patches of coral. At the same time, he suggested, the structures could provide additional hard surfaces on which corals would grow — and attract more fish.

Hawkins said he's more worried about commercial fishing. Bottom trawling and clam dredging could wipe out some shallow coral communities, he said. He has appealed — without success — for federal agencies to designate the shallower cold-water coral reefs essential fish habitat, which would give them a measure of legal protection.

Hourigan said "the patches we've seen have been relatively small patches. ... It's not immediately clear the extent to which what we see today is all there ever was or whether there was more once and it was destroyed."

Odell, whose organization is seeking to help map corals and other ecologically important features on the ocean bottom, said he's convinced that all of it needs to be shielded from fishing and offshore energy projects.

"The black sea bass absolutely depend on this coral patch habitat," Odell said. "We only roughly know where it is, and it has yet to be mapped and protected. … It's astounding that we have better maps of the surface of Mars than we do of the sea floor now."

tim.wheeler@baltsun.com

Copyright © 2014, The Baltimore Sun
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