Scientist’s projects are poles apart
David Kirchman has sailed among glaciers, walked with penguins, swum in the same icy waters as polar bears and seen ice-covered mountains so majestic they’ve taken his breath away.
Kirchman, who holds the title of Maxwell P. and Mildred H. Harrington Professor of Marine Studies at UD, is a veteran of scientific research cruises in the freezing waters of both the Arctic and the Antarctic, with more exciting voyages ahead in the International Polar Year.
For nearly a month this past winter, Kirchman lived and worked aboard the 249-foot research and supply vessel Laurence M. Gould in the Southern Ocean off western Antarctica, near Palmer Station, one of three U.S. research stations on the frozen continent.
The research cruise was part of the National Science Foundation’s Long-Term Ecological Research (LTER) Program, which is collecting data on a variety of ecosystems.
The LTER research effort at the Palmer Station site focuses on the ocean ecosystem off Antarctica. It has been under way since 1990.
Kirchman, an expert in marine microbiology, was invited to participate in the latest cruise by Hugh Ducklow, Glucksman Professor of Marine Science at the College of William and Mary, who is leading the Antarctic LTER project. The two scientists have been colleagues since they were doctoral students at Harvard more than 25 years ago.
One use of the long-term data collected in Antarctica is to document climate change and its impact on the ocean environment.
“There are already signs of it, such as the earlier melting of ice in the austral spring and longer periods of open water,” Kirchman says. The “austral spring” is September and October in the Southern Hemisphere.
“Data on ice coverage and ice-dependent animals indicate that the climate is changing rapidly and dramatically in the Antarctic environment,” he adds. “For example, Adelie penguins, which depend on ice, are decreasing around Palmer as the extent of ice coverage decreases. They are being replaced by other penguins that are less ice dependent.”
Adelie penguins are some of the top predators in Antarctica’s coastal marine ecosystem. According to LTER research, the penguin population near Palmer has declined by about 70 percent in the past 30 years in response to regional warming, decreasing sea ice and changes in the local food chain.
Kirchman’s role on the research cruise was to analyze the tiniest life at the base of the ocean’s food chain—the microscopic plants and animals collectively referred to as “marine microbes”—and their impacts on the carbon cycle, a complex series of exchanges that occurs among the atmosphere, land and ocean.
While carbon dioxide occurs naturally in the atmosphere, certain human activities, such as the burning of fossil fuels, can contribute to increased levels of the gas, strengthening the “greenhouse effect” and the subsequent heating up of the Earth.
“The ocean plays a major role in the carbon cycle,” Kirchman says. “In fact, some scientists have estimated that marine microbes generate more than half the oxygen on Earth.”
Throughout the 28-day cruise, Kirchman helped collect and analyze seawater samples taken at 60 locations in the Southern Ocean. While some measurements of microbial activity were done aboard ship, the DNA analyses of the samples now are under way in Kirchman’s lab at the Hugh R. Sharp Campus in Lewes, Del. The samples were put on ice and shipped to Delaware at the end of the cruise.
“I usually worked in tennis shoes and a sweater during the cruise because nearly all of my work was done inside,” Kirchman says. “I would just run from one lab to another lab on deck, spending only a few seconds outside.
“I think this is one of the biggest misconceptions about Antarctica. During the summer there, the temperatures are only around freezing. The wind is cold, and people working on the ship’s deck certainly wear warm clothes. But otherwise, Antarctica in summer is like walking around in Delaware in January—at least during a normal, cold winter.”
This was the second time Kirchman has conducted research in Antarctica. A decade ago, he participated in a research cruise aboard a different U.S. Antarctic Program ship, the 308-foot Nathaniel B. Palmer, in the Ross Sea.
During the past five years, he also has been on two of his UD laboratory’s four research cruises in the Arctic, all aboard the U.S. Coast Guard’s 420-foot icebreaker Healy.
It takes a little getting used to the noise and the stop-start motion of this Arctic vessel as it bangs its course through the ice, Kirchman says, but researchers eventually adjust as their scientific studies start humming along.
Kirchman will be returning to the Arctic this summer, this time to conduct experiments at the Barrow Arctic Science Consortium’s facilities in Barrow, Alaska’s northernmost city, located 340 miles north of the Arctic Circle.
While the Antarctic research is not directly linked to his Arctic work, Kirchman says he will be able to compare how the microbes from each environment adapt to life in perennially cold waters.
The one thing he says he most wants people to understand about polar research today is that humans have extended a much farther reach to the “ends of the Earth” than they realize.
“Antarctica is very forbidding and daunting, and it is hard to imagine that we could have any impact on it, being thousands of miles away,” Kirchman says. “But we do.”