Food web unraveling in Antarctic, thanks to global warming

Krill, the shrimp-like crustaceans at the center of the Antarctic food chain, are rapidly disappearing, and scientists suspect global warming may be the culprit. In some key ocean regions, krill have declined by more than 80 percent in the last 25 years, according to a study in today’s issue of the journal Science. Numerous Antarctic fauna rely on the thumb-sized critters for a large part of their diet, including whales, seals, penguins, squid, fish, and sea birds. Scientists trace the precipitous drop to a decline in sea ice — young krill rely on the cracks on the underside of ice to shelter them and provide them algae to eat — brought about by a rise in area temperatures of 4.5 degrees Fahrenheit over the last 50 years. And that, of course, many researchers attribute to global warming. They warn that a tipping point could be near. “What you would see then is a literal collapse of the food web,” said Antarctic researcher William Fraser. “All the predators would suffer some pretty drastic declines.”