Polar Plunge

Fur coats may not be enough for Weddell seals
In 2007, Horning’s research team studied Weddell seals in Antarctica. Here, they leave a seal to recover while they remove equipment before the ice melts. (Photo: Markus Horning. Research Permits NMFS #1034-1854; ACA #2007-007).

In 2007, Horning’s research team studied Weddell seals in Antarctica. Here, they leave a seal to recover while they remove equipment before the ice melts. (Photo: Markus Horning. Research Permits NMFS #1034-1854; ACA #2007-007).

With ice coverage shrinking in the Arctic and parts of the Antarctic, scientists are scrambling to predict future consequences. But one Oregon State University scientist isn’t as concerned with the ice itself as with the animals that use it to rest. Markus Horning, pinniped ecologist for the Marine Mammal Institute, will venture to the Antarctic in October to study Weddell seals (Leptonychotes weddellii), the southernmost mammals on the planet.

Horning and his colleagues Jo-Ann Melish and Allyson Hindle of the Alaska Sea Life Center want to know how these animals regulate body temperature and how they might fare in an environment with less ice. Weddell seals seem ideally adapted for polar seas. They sport a thin fur coat over thick layers of body fat, can exceed 1,200 pounds and dive for an hour or more to a depth of 2,000 feet.

“Although this might not be the biggest consequence of climate change, certainly the cost of spending more time in the water rather than hauled out on the ice might be important,” Horning said as he greased his boots in preparation for his upcoming expedition in his office at OSU’s Hatfield Marine Science Center in Newport. “We don’t have any idea what the cost might be.”

Past studies have attempted to model thermal regulation (the cost to an animal of keeping warm in a cold environment) in pinnipeds (seals, sea lions and walruses), but many of these estimates have been based on assumptions. It is difficult to collect energetic data on animals that dive long and deep under the polar sea ice.

Now, with support from the National Science Foundation, Horning, an associate professor of fisheries and wildlife, is collaborating with a company called Wildlife Computers to take another crack at analyzing the seals’ swim speed, body temperature and heat loss.

This team has worked with Weddell seals in the past, but this time new equipment may enable them to collect more information. They will place custom-built data recording devices (heat flux data loggers) on the animals to record the amount of heat lost to the environment. They will combine those data with the temperature and flow speed of the water, and with data on internal heat production by the animal, to measure the cost of thermal regulation.

“Surprisingly, that type of work has never been done on any kind of pinniped really swimming in cold waters under any kind of conditions,” Horning says. “And that is kind of a big knowledge gap, because a lot of estimations of the impact of climate change on ice seals are based on what we call an individual-based energetics model. So you kind of model all of the costs associated with the different activities in the life of a seal; then you can see how that might change if certain environmental conditions change.”

October heralds spring time and months of continuous sunlight in Antarctica. Horning’s team will watch the last sunset soon after arriving. Average temperatures will gradually increase to a point where Horning gladly welcomes the occasional day above freezing as he bundles up in warm clothing and treks across a disappearing world.

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Read updates about the Weddell seal thermoregulation project from Mee-ya Monnin, an undergraduate working in the Horning lab.

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