An Inquisitive Polar Bear
Summer is here in Delaware, but it's still polar-bear weather up north. Three marine scientists from the University of Delaware College of Marine Studies can tell you that firsthand. They recently returned from a six-week expedition in the Arctic Ocean off Alaska aboard the Coast Guard's 420-foot icebreaker Healy.
"One night, a polar bear came by an ice floe near the ship and started fooling with some of the scientists' gear," says research technician David Huntley. "He chewed on a tripod and ripped open an equipment case. Then he went and played with the floats from an ice mooring that had sediment traps under it."
Neither the ship's horn nor flares could shoo the bear away from his newfound toys. But eventually, after a couple of hours, the bear decided it had other things to do and went on "his merry way," according to Huntley.
Huntley, associate dean David Kirchman, and doctoral student Rex Malmstrom were part of a team of 50 scientists from 18 research institutions working at sea on the Western Arctic Shelf-Basin Interactions Program sponsored by the National Science Foundation and the U.S. Office of Naval Research. The five-year study, led by researchers from the University of Tennessee, is investigating the impact of global climate change on the North American Arctic.
During the expedition, Huntley oversaw the operation of the acoustic doppler current profilers, which are attached to the ship's hull to measure the velocity and direction of the water current. Every day, he processed the data from these instruments and relayed the information back home to Andreas Muenchow, associate professor of physical ocean science and engineering in the College of Marine Studies, for analysis.
While Huntley worked on collecting data on ocean currents, Kirchman and Malmstrom focused their attention on the freezing water's tiniest inhabitants.
There are about a million bacteria in one-fourth of a teaspoon of seawater. Kirchman and Malmstrom spent 16 to 18 hours each day in the ship's labs filtering, analyzing, and preserving the microbes they found in seawater samples collected at various depths.
They also conducted experiments to determine how efficiently bacteria grow in the extreme conditions of the Arctic. Knowing this information will help scientists better understand the role that microbes play in the Arctic's nutrient cycles, as well as better predict the impact that potential increased temperatures from global climate change would have on the ecosystem.
According to Kirchman, in other oceans, marine bacteria use about half the organic carbon produced by microscopic plants through the process of photosynthesis. But in the Arctic, it's not clear how much of this food is being used by bacteria.
"Some scientists think bacteria use a smaller percentage of the organic carbon from plant production in the Arctic because the water is so cold it inhibits the microbes from feeding. The water is -1.5°C (29.3°F), which is about as cold as seawater can get without freezing," Kirchman notes. "However, our preliminary evidence indicates that in the spring, the bacterial activity is low due to the lack of food, not from the cold temperature."
Now back in the lab at the Lewes campus, Kirchman says he and Malmstrom will be conducting DNA analyses on the microbial samples they collected at sea. The 200 liters of samples they processed at sea were distilled down to a couple of liters, frozen, and shipped to Delaware.
The scientists will be working with the samples for the next two years. During this phase of the research, they undoubtedly will discover new species of microbes, previously unknown to scientists, that can withstand the frigid waters of North America's polar region.
Kirchman says he won't soon forget the freezing temperatures and high winds of the Arctic, the intense research, or the occasional pickup game of basketball with colleagues on the ship's flight deck, where helicopters would land periodically to deliver supplies. He says he can even add going on a true "polar bear swim" in subfreezing waters to his list of personal accomplishments.
Working at sea in the Arctic Ocean is both exhilarating and challenging, but the research investment is critical and well worth the effort, Kirchman notes.
"The Arctic is thought to be potentially affected more by global climate change than elsewhere," Kirchman says. "Even a small increase in water temperature in the Arctic could have a big impact on the microbes that are the focus of our study and ultimately on what happens with larger organisms like polar bears."
Next week, another member of Kirchman's laboratory, research associate Matthew Cottrell, and Alex Parker, who recently received his doctorate in oceanography from the UD College of Marine Studies, will set sail for six weeks on the final leg of the Western Arctic Shelf-Basin Interactions Program.
Photos courtesy of Teachers and Researchers Exploring and Collaborating (TREC), funded by the NSF Arctic Sciences Section.