March 14, 2003

Antarctica's Colorful Garden

Bakers says eating a bite of this sponge would be "like eating fiberglass." More Pictures

Bill Baker sits unsteadily on the inflated edge of a bobbing Zodiac boat. He's encased from top to bottom in a heavy black rubber suit, part of the protection he needs for diving to the sea floor in these icy Antarctic waters. Baker is a "natural products chemist" who studies the chemical composition of organisms. He carries out two distinct, but related, branches of research. One area, chemical ecology, is the study of how life uses chemicals in the never-ending battle between predator and prey. The other area, bio-prospecting, is the search for useful chemicals, mostly as possible new medical cures, hidden in the tissues of plants and animals.

I'm in the boat with Baker, a professor at the University of South Florida, on assignment as a tender: a sort of modern-day, Antarctic butler helping the scientist and his two assistants get their diving duds on. Above the surface the Antarctic environment is bleak-all rocks and snow with dashes of green vegetation. But under the surface, Baker says, Antarctic is a colorful "garden" with hundreds of species of brilliantly colored sponges, corals and tunicates (of which the sea squirt is one member). These exotic species completely carpet the ocean floor and the walls of underwater canyons. Baker and his crew have come up with equally colorful names to describe them, such as the "snot tunicate," the "turd tunicate" and the "lollypop tunicate." My job as tender is to help divers suit up, to stand watch on the surface while the researchers are below and to pull them into the boat when they return. The divers each wear two pairs of long underwear, a fleece-lined body suit and a waterproof rubber shell. After donning all these layers, they are almost as helpless as beached whales and need assistance putting on their rubber gloves and breathing gear.

Once he's completely dressed, and loaded with 160 pounds of gear, Baker slowly leans back off the boat's edge and falls headfirst into the dark water. Before long all three divers have disappeared below the gentle swell. A circle of bubbles shows where they are.

There's not much to do while the crew is below other than enjoy the scenery and look for leopard seals. There are no known incidents of leopard seals attacking humans, but these animals are vicious, powerful hunters that could easily kill a diver. This season some of the local leopard seals have been very curious (or possibly very aggressive, its hard to say which) and have approached within several feet of Baker. "They could take us if they wanted to," says Baker. When tenders see a leopard seal they bang a piece of metal on an oxygen tank, both to warn the divers and to frighten the seals. At that point, says Baker, "the dive is over."

Baker and his team are below for less than an hour. They only carry about one hour's worth of air, but it's the cold that limits the dive. Even with four layers of clothing, an hour is just about as long as they can withstand water that's only about 32 degrees Fahrenheit. The dive was a success. Kevin Peters, a graduate student at the University of Alabama found "the catch of the day," a bright red sea sponge about the size and shape of a veal cutlet.

Back at Palmer Station the samples are freeze-dried. Some will be processed further here while others will be saved for later studies. The first stage of the laboratory research is to determine if the harvested organisms are toxic to the chief seafloor predator here, the starfish. Baker says organisms have many ways of ensuring their survival. Sometimes they have protective shells (like turtles), sometimes they grow quickly (like weeds) and sometimes they contain toxins (like poison ivy). Few of the seabed animals in Antarctica have physical defenses like shells. Most don't appear to survive by growing fast. So Baker expects many to use toxins for defense. One way to find out if they do is by cutting them up and feed pieces to a tank full of starfish. Samples that are refused by the star fish either don't taste good or are poisonous.

The animals that appear to be toxic (or "have chemistry," as Baker puts it) may contain medically useful compounds. Baker says about 60 percent of all drugs in use today originated with plants or animals. He says after a decade of studying Antarctic creatures he's convinced that these organisms are loaded with useful compounds. Two chemicals isolated by other researchers from tunicates are currently undergoing trials for use as anti-cancer drugs. Baker will spend the coming months and years trying to purify and synthesize the compounds that make some of his samples unpalatable to star fish.

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