Mother Superior's Secrets

By Anastasia Toufexis

David Long sounded as excited as a passenger aboard a space shuttle. "It was spectacular," he burbled. "It was like sitting in a big bubble and looking at a movie playing in front of you. We found sheer cliffs, we found pockmarked holes like dimples on a golf ball. And we found these little red marks all over the rocks." Long's exhilaration came not from leaving the earth's surface but from going beneath it, on the first submarine exploration to the bottom of one of the world's biggest bodies of fresh water, Lake Superior.

Long, a geochemist at Michigan State University, is one of a team of scientists who spent eight days last month exploring Lake Superior in the submersible Johnson-Sea-Link II. Their voyage was the first leg of a four-week, $550,000 expedition sponsored by the National Oceanic and Atmospheric Administration that will continue until Aug. 20. Until now researchers have seldom viewed Superior at depths below 200 ft., generally the limit to which scuba divers descend. But using the Sea-Link, they have been able to plunge right to the bottom. The deepest point: 1,330 ft.

The red blotches discovered on rocks as deep as 1,300 ft. provided an early, startling dividend of the expedition, the scientists disclosed last week in Marquette, Mich. Using a pair of tweezers, a biologist plucked a red spot from a stone that had been taken to the surface and placed it in a vial of water. Immediately the spot sprouted tentacles and unfolded into a hydra, a primitive invertebrate. "We were expecting that at these depths Lake Superior would be a biological desert," said Team Member John Krezoski, a biologist at the University of Wisconsin, Milwaukee. "We're coming away dazed and astounded."

Indeed, the bottom of the lake, a gray moonscape punctuated by boulders, rock-slides and l00-ft.-high sandstone walls, was teeming with life. Clouds of minute zooplankton drifted across the sub's windows like snowflakes. Burrowing burbot fish dug deep trenches in the silt, while sculpin fish created dimple-like holes as they nestled into the lake floor.

Two scientists and two crew members from the parent research vessel Seward Johnson took turns making the twice-daily three-hour dives in the Sea-Link. Originally built for ocean submersion, the craft had to be packed with a special foam embedded with air-filled glass bubbles to provide the greater buoyancy needed in less dense fresh water. The Sea-Link looks more like an underwater helicopter than a submarine. It has a bubble-like cockpit that seats the pilot and a scientist, and its nine reversible thrusters allow it to move in any direction or hover in place. Cameras and lights are mounted on the outside, as are racks to hold buckets for samples grasped by the robotic arm or sucked up by a vacuum tube.

The underwater exploration was at first plagued with problems, including poor visibility and bursting collection sacks. But after the first two days exploration and sampling went more smoothly. Exulted Long: "We've got rock formations that will knock your socks off !" The investigations planned for the Sea-Link will ultimately involve 27 scientists. Some will survey the spawning habits and conditions of lake trout. Others plan explorations to the wrecks of five ships thought to have sunk between 1880 and 1918 for relics of shipboard life. Because of low water temperatures and the relative lack of oxidation, "the Great Lakes provide excellent preservation, even of shoes and leather," says Kenneth Pott, curator of the Lake Michigan Maritime Museum.

A major focus of the expedition is pollution. Although concentrations of many contaminants have been markedly reduced in the Great Lakes (Superior is the cleanest), toxic chemicals like PCB remain a problem. Researchers plan to devote 16 dives to studying the nepheloid, a cloudy, particle-laden 6-in. layer of water just above the lake floor that seems to trap, and then rerelease, pollutants. "We had thought that bottom sediments were sort of permanent sinks for contaminants attached to particles," explains Steven Eisenreich, a professor of environmental engineering at the University of Minnesota. "Now we're finding out that under certain conditions these particles get recycled."

A clue to how pollutants travel may lie hi the giant furrows (up to 3 ft. deep and 20 ft. across) that stretch for miles along the lake floor. Scientists think that the trenches, similar to those on ocean bottoms, are carved by currents of water that can also disperse toxic material. Other investigators will concentrate on collecting two shrimp like organisms in the food chain, including Ponto-poreia hoyi, that dwell on the sediment and may ingest toxic chemicals.

Scientists hope that findings from the Sea-Link will point to solutions for some of the Great Lakes' continuing problems. With the expedition only a third over, researchers were already counting it a success. Richard Cooper, a marine biologist at the University of Connecticut and the scientific director of the project, declares that before the last dive, "we expect Mother Superior to yield up more of her secrets. We're finding things that will rewrite the book on ecology in the Great Lakes." --By Anastasia Toufexis. Reported by J. Madeleine Nash/Marquette

With reporting by Reported by J. Madeleine Nash/Marquette