Scientists Say Emperor Penguins Threatened by Antarctic Sea Ice Loss

Posted on June 26, 2012

Scientists are projecting a major decline in emperor penguins by the end of this century as climate change reduces the extent of Antarctic sea ice. The study, led by the Woods Hole Oceanographic Institution (WHOI), with co-authors from the National Center for Atmospheric Research (NCAR) and other organizations, focuses on a much-observed colony of emperor penguins in Terre Adelie, Antarctica. The authors conclude that the number of breeding pairs in this colony may fall by about 80% by 2100.

The study used a set of sophistical computer simulations of climate as well as a statistical model of penguin demographics. The authors stress that their projections contain large uncertainties, because of the difficulties in projecting both climate change and the response of penguins. However, almost all of their computer simulations pointed to a significant decline in the colony at Terre Adelie. The 81% decline by 2100 was the median decline predicted by the simulations. The scientists say there is a 43% chance of an even greater decline, of 90% or more.

Stephanie Jenouvrier, a WHOI biologist, says, "Our best projections show roughly 500 to 600 breeding pairs remaining by the year 2100. Today, the population size is around 3,000 breeding pairs."

Jenouvrier noted that another penguin population, the Dion Islets penguin colony close to the West Antarctic Peninsula, has disappeared, possibly because of a decline in Antarctic sea ice.

At nearly four feet tall, emperors are the largest species of penguin. They are vulnerable to changes in sea ice, where they breed and raise their young almost exclusively. If that ice breaks up and disappears early in the breeding season, massive breeding failure may occur, Jenouvrier says. Disappearing sea ice may also affect the penguins' food sources. They feed primarily on fish, squid, and krill, a shrimplike animal that feeds on zooplankton and phytoplankton that grow on the underside of ice. If the ice goes, Jenouvrier says, so too will the plankton, causing a ripple effect through the food web that may starve the various species that penguins rely on as prey.

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The study was published here in the journal Global Change Biology.

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