UCSC researcher will describe scientific voyages to Antarctica in a public talk at the Seymour Center on Wednesday, March 12

As chief scientist aboard the research vessel Laurence M. Gould, Daniel Costa led a research team investigating the ecology of the Southern Ocean around Antarctica on two cruises in 2001 and 2002. Costa, a professor of ecology and evolutionary biology at UC Santa Cruz, will share his experiences conducting research during the harsh Antarctic winter, along with breathtaking photos he took along the way, in a public lecture and slide show at Long Marine Laboratory.

The lecture will take place at the Seymour Marine Discovery Center on Wednesday, March 12, from 7 to 8:30 p.m. Admission is $6 for the general public and $4 for members of the Friends of Long Marine Lab.

The biologically productive waters off Antarctica support trillions of shrimplike crustaceans called krill that play a central role in the ecology of the Southern Ocean. Animals that feed on krill include commercially important fish, seals, whales, penguins, and other seabirds. How the krill and their predators survive the long, cold polar winter is one of the questions the researchers on the Laurence M. Gould set out to answer.

The cruises were part of the Southern Ocean component of the Global Ocean Ecosystems Dynamics survey (SO GLOBEC), which is part of a wider international GLOBEC program funded in the United States by the National Science Foundation. The program was set up to study how marine life is affected by environmental change. Costa serves on the executive committee of the SO GLOBEC program, in addition to his role as chief scientist on the two cruises.

Because so many top predators concentrate on krill as their primary food source, scientists have been concerned about the vulnerability of the Southern Ocean ecosystem to environmental perturbations, such as climate change, Costa said.

"One of our main goals is to understand the role of climate in driving the ecosystem of the Southern Ocean," he said. "We'd like to know, for example, what factors determine the number of krill that survive the winter."

The program's field studies involved two research vessels, the Laurence M. Gould and the Nathaniel B. Palmer. As chief scientist of the Laurence M. Gould, Costa was responsible for coordinating the work of a diverse group of researchers, while conducting his own research on crabeater seals.

Despite their name, crabeater seals eat mainly the shrimplike krill. They have evolved elaborately shaped interlocking teeth that they use to filter krill from the water. Although they are probably the most numerous seals in the world, crabeater seals have been difficult to study because of their remote habitat.

To follow the movements of crabeater seals and study their feeding behavior, Costa used electronic tags that transmitted signals to the researchers via satellite. Satellite tags were also used to study the movements of Adélie penguins.

Other researchers on the cruise focused on whales, krill, the algae that live in sea ice, and various aspects of the physical environment. An unexpected finding from the 2001 field studies was the occurrence of "hot spots," areas of abundant Antarctic krill where predators such as minke whales, humpback whales, seals, and penguins were also found in large numbers.

Conducting field studies in the Antarctic winter was hard work, but the researchers also found time to have fun, Costa said. In his talk at the Seymour Center, Costa will try to convey a sense of what life was like on the cruises, while presenting some of the scientific findings to come out of the SO GLOBEC program.