Polar Bear Bones Signal Changing Arctic Environment
Study of archaeological specimens from apex predator reveals stable food web for thousands of years, but the web could be shifting
In a newly published study, researchers at Trent University have found some interesting insights into the consequences of a warming Arctic climate.
Environmental & Life Sciences Ph.D. student Jennifer Routledge '13 (Peter Gzowski College) looked at potential changes in polar bear foraging over four millennia.
Using archaeological bone collagen samples from a polar bear subpopulation of the Lancaster Sound Region of the Canadian Arctic Archipelago, Jennifer found that the marine food web here was stable despite previous climate shifts, such as the Medieval Warm Period (950—1250 A.D.) and the early stages of the Little Ice Age (1300—1850 A.D.).
“The ecosystem just hummed along normally during these climate anomalies,” says Routledge, the lead author of the paper, which was published in the journal Anthropocene. “But comparing modern and archaeological samples, we see the base of the modern polar bear food web changed significantly.”
As apex predators in the Arctic, polar bears can tell us a lot about the state of today’s Arctic ecosystem.
“Studying polar bears gives us a bit of a grand scale look at the entire food web to see how things are changing,” says Routledge. “They walk around on land, but they’re considered marine mammals because they only consume from the marine environment. They have to forage from the ice.”
Today, the rise in global temperatures is causing a significant loss of sea ice, which supports the entire Arctic food chain. At the base of the food chain is sea ice algae, which grow in underwater channels beneath the ice.
“In this more open-water, ice-free environment, we’re seeing less sea algae and more phytoplankton in the food web. This affects the fish that the seals hunt, and therefore effects the seals that the polar bears hunt,” says Routledge.
While the polar bear sub-population in Lancaster Sound appears stable, the research findings offer a glimpse into the changes we could expect to see in the Arctic food chain. That’s reason to pay more attention to changes in Arctic ice, and to polar bears.