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Their find: splendor on the sea floor

A USF St. Petersburg team has made an astounding - and important - discovery: the deepest coral reef in the United States.

By TAMARA LUSH
Published January 2, 2005

	[USF St. Petersburg]
	The sea floor at Pulley Ridge, an area in the Gulf of Mexico west of the Dry Tortugas, is covered with plate corals.

In 1999, a team of USF researchers left St. Petersburg on the R/V Bellows and sailed 24 hours southwest to the deep waters of the Gulf of Mexico.

About 50 miles west of the Dry Tortugas, the ship slowed. The researchers hurled a steel bucket attached to a chain to get a sample of the ocean floor and watched it sink 200 feet. They dragged it for a bit and then hoisted it back to the deck.

The contents stunned them: Bright purple coral shaped like dinner plates were tangled in a bouquet of green, leafy algae.

"What the heck is this?" said researcher Bret Jarrett.

It would take four years, hundreds of thousands of dollars in research grants and six more trips to the area before they determined what they had discovered:

The deepest coral reef in the United States, 20 miles long and 3 miles across at its widest.

It has been sitting there for centuries, a pristine fish habitat, a breeding ground for coral and green algae rarely found in the Gulf of Mexico. No one knew it was there, though some fishermen may have suspected something because of the big grouper that swim in the depths. But the reef itself was uncharted.

"It shows that even in this day and age that we have a lot to learn about sea floor resources, even in our own backyard in the Gulf of Mexico," said Brian Keller, science coordinator at the Florida Keys National Marine Sanctuary. "Our knowledge of coral reefs is still so rudimentary in many ways - and we're still discovering them."

Now officials who oversee the gulf wonder how to preserve what for the researchers is a once-in-a-career discovery.

Geological oceanography is not quick science.

The USF St. Petersburg research team went on its first expedition in 1996 for Jarrett's dissertation, sailing just west of the Keys and mapping the bottom of the ocean floor with sonar.

Team members looked at a bathymetric map - a topographical map of the ocean floor - and saw a "bump" west of the Dry Tortugas. The bump was near a vast area called Pulley Ridge, named after the late Dr. T.E. Pulley, a malacologist (that's someone who studies clams and mollusks).

"Let's go and check it out," said Al Hine of the USF College of Marine Science. The other team members - Jarrett, Bob Halley of the U.S. Geological Survey and Stan Locker, a USF geophysicist - agreed to go.

It was too deep to see the bump with the naked eye. But to get to the bottom, they would need better equipment and more research trips.

That takes money.

Jarrett, who was making $15,000 a year working on his doctorate, co-authored many of the grant proposals. The team received some grants - $100,000 in 1999 alone - that funded more trips.

But for at least two years they weren't sure exactly what was at the bump near Pulley Ridge; they had some suspicions, each of which was confirmed over the course of six research voyages.

"We kept discovering new things," Jarrett said. "And the research cruises are generally once a year, so the next thing you know, four or five years can go by."

In the summer of 1999, the team had obtained enough grant money to take the ROV - for remotely operated vehicle, a piece of equipment the size of a refrigerator with a video camera on top - on a cruise. Earlier, they had tried to map the area with sonar.

Once at Pulley Ridge, they dropped the robot to the sea floor. On deck, a scientist controlled it with a joystick, like a video game.

The rest of the team watched the live images on a video monitor. What they saw stunned them as much as when they saw the coral in the bucket just months earlier.

"We were all blown away by this bizarre, flat, living sea floor covered with blue and brown corals and lettuce-like green algae," Jarrett said. They had expected to see some coral, but not that much.

The video revealed a stunning number of fish, both deep and shallow water species: giant red grouper, scamp, damselfish, angelfish, rock beauty, hogfish and bass.

The lettuce-like algae - Andaymonene menzeii - is "unusual, if not unique at this depth in the Gulf of Mexico," the researchers later wrote.

The fields of tan-brown and blue-purple coral were healthy, Hine said, with about 60-70 percent living. In comparison, he said, the coral reefs near the Keys - popular for snorkeling - are 5 percent live.

The Keys feature shallow-water coral, which grows vertically. The best-known types are "head corals," such as brain coral, but there are also elkhorn and staghorn corals, although in recent decades, staghorn and elkhorn coral have died off. The Pulley Ridge coral - agaricia - is flat because it has adapted to the low light.

"Corals require light to grow, and so they spread out laterally as opposed to vertically," Jarrett said. "They've adapted to the situation, they've maximized the sunlight."

On another cruise, they took sonar images of the reef. The image on the sonar screen developed slowly.

Jarrett said the images reminded him of the invisible-ink coloring books he had as a boy - and of the anticipation of finding out what image is hidden on each page.

It was after those trips that the team realized what the "bump" was.

Not only was it a living, healthy coral reef. It topped what was once a barrier island.

The researchers determined that the island - it has the same kind of ridges, valleys and other characteristics of barrier islands around Florida - was engulfed by water about 13,000 years ago, when the sea level rose after the last glacial event.

Coral are living things, and they need light to survive and reproduce.

That's why the USF find was significant - the coral at Pulley Ridge is surviving in 200 feet of water, with little light. There are deeper coral reefs, where that type of coral does not need sunlight to live.

The Pulley Ridge coral was very healthy, Hine said.

"In the last 20 to 30 years, coral reefs have just taken a beating," Halley said. "They're dying."

But not Pulley Ridge. The overall health of the reef means the coral can propagate. Coral reproduce both asexually and sexually, with sperm and eggs. The tiny corals float to other reefs and attach themselves to rocks, and become the bedrock of a healthy marine ecosystem that includes fish and algae.

"This type of habitat structure can serve to attract fish," said Keller, whose sanctuary office is based in Marathon in the Florida Keys. "It creates an oasis of sorts for marine life in deep water."

The ocean's warm water - it is about 70 to 80 degrees at Pulley Ridge throughout the year - circulation patterns and clarity all contribute to the health of the reef.

For the research team, the possibilities are limitless - they have discovered something that other geologists or oceanographers spend their entire careers looking for.

Researchers from different fields - marine biologists to specialists in rock sediments - can scrutinize Pulley Ridge. They can also try to figure out why the coral is so healthy there compared with shallower reefs.

The team has already worked twice with Sylvia Earle, a noted scientist with the National Geographic Society, who twice sent a small submarine to Pulley Ridge in 2000 and 2001.

The researchers have documented their findings and presented them to a national geologic and oceanographic convention. Next year, an article detailing the research will be published in the Journal of Marine Biology.

Jarrett completed his doctorate and devoted a chapter of his dissertation to Pulley Ridge. He said he is about to begin a temporary teaching post at Colby College in Maine, where there is little coral to be found.

The research team also hopes to preserve Pulley Ridge.

Halley, of the U.S. Geological Survey, presented the group's research to the Gulf of Mexico Fishery Management Council in 2003, which will decide in the coming months whether to restrict fishing or trawling in the area. A public hearing is scheduled for Tuesda y in Key West.

Pulley Ridge was designated by the management council as a Habitat Area of Particular Concern this year.

"I think it's in pretty good shape right now," Halley said. "But eventually, people will start impacting it if it's not protected in some way. I would like to see regulations put in place to limit the kinds of fishing that might impact the bottom of that area."

Tamara Lush can be reached at 727 893-8612 or at lush@sptimes.com

[Last modified January 2, 2005, 00:22:32]