Follow the bouncing buoy

Maybe the ship's buoy just wanted to see the world when it broke away from the mooring lines on UD's research vessel Cape Henlopen as the crew was taking water samples in the Atlantic Ocean north of Atlantic City, N.J., two summers ago.

"You always hate to lose a piece of equipment," says Art Sundberg, assistant director of marine operations, "but occasionally it happens when you're working at sea. If it's a sensor that emits a radio signal, sometimes you can track it and retrieve it. In the case of a mooring buoy like this one, you never really expect to see or hear from it again."

When its ride on the ocean waves finally ended, the buoy was a long way from home. In fact, it practically washed up on Helen Smith's doorstep. She lives in the village of Middletown on St. Martins, one of the few inhabited islands of the 40 that constitute the Isles of Scilly (pronounced "silly"), 28 miles off the southwestern tip of England.

Smith and a male friend, Viv Jackson, discovered the yellow-and-gray buoy marked "University of Delaware" as they were walking along the beach last January.

"Wrecking," or beachcombing, is a popular hobby of residents and tourists alike on the Isles of Scilly. The British often refer to the archipelago as "the Fortunate Isles" due to their pleasant climate tempered by the warm waters of the Gulf Stream. While the islands have fewer than 2,000 residents, they beckon increasing numbers of tourists for activities ranging from sunbathing and scuba diving to sailing, fishing and bird-watching.

Fewer than 100 persons live on the island of St. Martins, with its stunning views of rugged cliffs, heath-covered fields and sandy beaches leading to azure waters. Smith and Jackson raise sheep there and grow narcissus for export in the Isles of Scilly's longstanding flower trade.

"There is no algal growth, and the condition of the buoy is good," Smith wrote in a letter to the University days after discovering the buoy. "We are interested in where the marker was positioned in the Atlantic and how long it had taken to reach us."

Like the castaway's message in a bottle that winds up on faraway shores, the UD buoy's journey offers a fascinating lesson about ocean currents--the "streams" or "rivers" in the sea that are constantly in motion, fueled by winds and variations in water temperature.

"When I saw Mrs. Smith's message, it reminded me of research we conducted years ago," says Richard Garvine, Maxwell P. and Mildred H. Harrington Professor of Marine Studies. A member of the UD faculty since 1977, Garvine conducts research and teaches courses in the College's Physical Ocean Science and Engineering Program.

"One of my students had deployed Woodhead drifters to track currents flowing out of the Delaware Bay," Garvine says. These plastic floats resemble long-stemmed mushrooms about the size of a dinner plate. "Most of the drifters were retrieved, but some of them got away from us. In fact, about a year after the deployment, we got several back from England."

An expert in fluid dynamics, Garvine has played a major role in revealing how coastal and ocean waters move in the mid-Atlantic region. Nearly two decades ago, he discovered the Delaware Coastal

Current. This strong current flows out of Delaware Bay, takes a right turn and then continues to hug the coast until it diminishes along the northern shores of North Carolina.

The current helps explain the UD buoy's path to the British Isles, Garvine says.

"That buoy probably got caught up in the Hudson Coastal Current, which flows out of New York harbor past the New Jersey coast," he says. "Then it hooked into the Delaware Coastal Current, which shuttled it farther south along the coastline."

The buoy's longest ride came next, when it floated into one of the eddies that flank the Gulf Stream, north of Cape Hatteras, N.C. Once it entered the Gulf Stream--one of the ocean's largest surface currents, spanning about 300 miles at its widest and more than 300 feet deep--the buoy traveled northeast, as if on a meandering conveyor belt, across the Atlantic Ocean. Garvine says he suspects that one of the Gulf Stream's sub-currents eventually delivered the buoy to the Isles of Scilly.

Garvine estimates that the buoy's trip was in the neighborhood of 3,000 nautical miles and that it traveled at 10-20 feet per minute, which is the typical current speed of the North Atlantic Drift, the extension of the Gulf Stream that flows toward the west coast of Europe.

Thanks to the Gulf Stream and the large eddies that flank it, the British Isles are on the receiving end of a lot of flotsam and jetsam, Garvine notes. "There have been a number of shipwrecks through the ages as well along the Isles of Scilly," he says. "If you live there, it's probably second nature to look to the sea to see what will be delivered next."

A few months ago, when Helen Smith received a phone call from the UD Marine Public Education Office about the buoy, she laughed as the caller admitted little prior knowledge of the Isles of Scilly.

"That's all right, really," Smith said. "When we found the buoy, we had to look up Delaware on a map."

With the UD buoy mystery solved, Smith can add the story to her collection of "wrecking" finds. She says some of her other discoveries include whale carcasses, coconuts and messages in bottles from as close as Ireland and as far away as Quebec.

--Tracey Bryant