February 23, 1995 Contact: Robert Irion (408/459-2495)

UC SANTA CRUZ RESEARCHERS EXPLORE ANTARCTIC FOOD WEB

FOR IMMEDIATE RELEASE

SANTA CRUZ, CA--November in Antarctica: sunshine round the clock, melting ice, calm weather. Perfect conditions for an explosion of plant growth in the water, fueling a future feeding frenzy for penguins, walruses, whales, and seabirds. A perfect time, too, for a cruise to study the workings of this food web--the foundation of one of the planet's most lush ecosystems.

For UC Santa Cruz scientists David Garrison and Marcia Gowing, the November 1994 cruise was no QE2 vacation. Rather, they and about 30 other researchers put in long days to gather as much information as possible on the microscopic aquatic life that teems off the white continent each spring. The voyage took place in an ice- free zone within the highly productive Ross Sea, some 2,000 miles south of New Zealand. It offered researchers their earliest glimpse yet into Antarctica's short but intense growing season.

Careful analysis of the hundreds of water samples and millions of organisms preserved by Garrison and Gowing may yield clues to some intriguing mysteries: Which types of algae are most critical to the food web? Could the ozone "hole" over Antarctica affect their life cycles and disturb the entire ecosystem? How much carbon do the organisms remove from the air, and could this help forestall global warming?

"There is concern about increasing levels of carbon dioxide in the atmosphere," Garrison says. "We don't know how much is taken out of the air by these blooms of plants and how much gets down into the deep water via the food web. If a lot of carbon does sink into deep water, it can be sequestered there for hundreds of years."

Garrison and Gowing, associate research biological oceanographers at UCSC's Institute of Marine Sciences, are veterans of Antarctic studies. The latest cruise, which lasted from November 3 to December 10, was the seventh for Garrison and the third for Gowing. They were aboard the Nathaniel B. Palmer, a research vessel chartered by the National Science Foundation as part of its U.S. Antarctic Program. This cruise was marked by relatively mild conditions (near 20 degrees F), few storms, hordes of penguins and seals, and lots of 20-hour days. "It was very tiring," Garrison says. "We worked essentially the entire time we were there."

Departing from New Zealand, the ship took a week to reach the Ross Sea's 300-mile-wide "polynya," an area of open water surrounded by ice. The aim was to catch the start of the annual bloom of phytoplankton--tiny algae on the menu of krill and other small animals, which in turn fortify fish, penguins, whales, and the rest. Scientists on previous cruises had seen only the height of this planktonic eruption, in December and January. As it turns out, even the latest cruise wasn't early enough: The water already was full of chlorophyll when the ship arrived. Researchers now think the plankton may start to thrive in October or even in late September, under the steadying influence of a thin layer of ice that lets sunlight filter through.

Even with the bloom well under way, Garrison and Gowing had no trouble meeting their goals. They collected huge amounts of Phaeocystis, a type of algae that begins life as single cells. During blooms, the cells form free-floating colonies that may include thousands of cells in a gooey matrix. Later, the colonies break apart. Colonies that aren't eaten appear to sink to the bottom, dragging carbon with them. In one part of the Ross Sea, the scientists found that the dominant plants were diatoms, a different kind of algae that uses silica to form glassy shells.

During three excursions across the polynya, the team took water samples at various depths, brought up organisms with gentle nets, and used traps to collect living and dead material drifting down through the water. They studied some of the samples on board with a technique that makes the chlorophyll in plant cells glow under a microscope. Most of the analysis, however, will occur during painstaking lab work over the next two years. Garrison and Gowing will use electron microscopy and other methods to measure the abundance of different organisms, estimate how much carbon they carry, and tease out the fine details of the food web.

"It boils down to a lot of counting," says Gowing. "Much of the work is to see who's feeding on whom. It's not a simple food web-- there seem to be as many interesting and diverse relationships among species here as there are in tropical waters. The more we look, the more we find."

The ultimate goal is to create a model of the annual cycles of carbon in the Southern Ocean. Biological, geological, and chemical processes all move carbon among land, sea, and air. Researchers cannot understand the big picture about these critical cycles without knowing how the smallest but most common organisms use carbon, and what happens to the carbon once they die.

Further, a better grasp of the biology of these life-forms will help researchers look for the effects of the ozone "hole." From May to October each year, industrial chemicals in the air deplete the ozone over Antarctica, letting more ultraviolet light reach the ground and ocean. Scientists theorize that single-celled plants and animals at the heart of the food web could feel the brunt of the damage caused by extra UV light--but finding evidence of that will take time.

Evelyn Lessard, a biological oceanographer at the University of Washington, is a coprincipal investigator with Gowing and Garrison on their NSF-funded study.

Editor's note: To reach Garrison and Gowing, call their lab at (408) 459-4789. Gowing departs on March 2 for another cruise, in the Arabian Sea.

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