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FOR IMMEDIATE RELEASE: July 7, 2008
Contact: Gina Hebert; ghebert@mbl.edu
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New Ecosystem is Forming as Western Antarctica Rapidly Warms, MBL Scientist Reports
MBL, WOODS HOLE, MA—Dramatic shifts in the food web are emerging on the Antarctic Peninsula, where the climate is warming faster than anywhere else on Earth, report three polar scientists, including MBL Ecosystems Center director Hugh Ducklow, in the July/August cover story of American Scientist.
Working out of Palmer Station in Western Antarctica, where the average midwinter temperature has climbed by 6 degrees C since 1950, the scientists are observing widespread changes in a polar ecosystem where nearly all species are attuned to the seasonal cycles of sea ice. Springtime sea ice is melting ever-earlier, and winter ice is forming later, amounting to a 90-day loss in annual sea-ice cover since 1978. If the warming trend continues, Ducklow says, “within about the next 50 years, the mean winter temperature will be warmer than the freezing point of seawater. At that point, no sea ice forms,” which will bring about a regime change in the ecosystem.
Ducklow studies marine plankton, the base of the food web in Antarctica. The algae that live in sea-ice pockets during the winter are rapidly losing habitat. This, in turn, is diminishing the population of Antarctic krill – small crustaceans that, as juveniles, congregate near the bottom of sea ice, forage on the algae, and keep away from predators. Krill are the preferred food source for penguins, whales, and other top predators in Western Antarctica, and it is unknown what they will eat as krill disappear. Ice-dependent seabirds and seals, such as the Adélie penguin and the Weddell seal, are in rapid decline near Palmer Station. They are gradually being replaced by non-ice-dependent species that are migrating into the area.
“We are looking at a replacement ecosystem which doesn’t have any analogue in the historical or fossil record,” says Ducklow. “A very interesting area of research for us is to try and construct (future) scenarios.” According to the Intergovernmental Panel on Climate Change (IPCC), this lack of historical analogues is a general problem in predicting the effects of climate warming. “There will be an ecosystem” in Western Antarctica, Ducklow says. “It will just be different.”
Other consequences of climate warming in Antarctica are discussed in the article, such as spring blizzards and ocean acidfication. Ducklow’s co-authors are James McClintock of University of Alabama at Birmingham, and William Fraser of Polar Oceans Research Group, Sheridan, Montana.
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