Ecosystem of Antarctic Peninsula is Changing Fast, Thanks to Global Warming

by Hannah Punitha on Jul 13 2008 3:45 PM

Scientists have determined that the ecosystem of the Antarctic Peninsula is changing fast, driven by warming waters and a loss of sea ice.

According to a report in Discovery News, these findings have been made by three researchers who have spent decades studying Antarctica's denizens.

These researchers have observed interconnected changes at the bottom of the Earth that are changing the ecology of Antarctica over just decades after some 30 million years of relative isolation.

"The changes are profound," said Hugh Ducklow of the Marine Biological Research Laboratory in Woods Hole, Massachusetts.

He and colleagues James McClintock of the University of Alabama at Birmingham and William Fraser of Polar Oceans Research Group in Sheridan, Montana, compiled their findings from studying different aspects of the Antarctic ecosystem.

Nowhere on Earth is climate change happening faster than on the neck of land stretching north from the Antarctic continent more than 900 miles toward South America.

he average midwinter temperature on the Antarctic Peninsula has increased more than 10 degrees Fahrenheit since 1950, five times the global average.

The changes the researchers see begin at the base of the food web, with phytoplankton - tiny photosynthetic organisms that, in Antarctica, are evolved to live in the sea ice.

As the extent of sea ice has decreased, so has the amount of phytoplankton.

"Sea ice is not just ice, it's a habitat for organisms," said Ducklow.

Juvenile krill, tiny shrimplike organisms that serve as the main food source for Adelie penguins and baleen whales, graze on the phytoplankton under the sea ice.

"Juvenile forms of krill are not as strong swimmers as adults," said Ducklow. "By congregating on the underside of the ice, they get a shelter from predators, and it's where the food is," he added.

Krill have been declining for decades, although sea ice decline may not be the only reason.

With less krill to feed on, organisms at the top of the food chain like Adelie penguins suffer. Their populations have been decreasing in the central and northern Antarctic peninsula.

The Adelie penguins also rely on the sea ice directly.

In winter, they use the sea ice to get out to hotspots of food. As this shrinks, their food will be too far away to swim to.

It is clear that the ecosystem that emerges will be different from the one that has existed in isolation for millions of years.

According to Ducklow, "We're seeing things happen rapidly there. It's a good wakeup call for us that there is climate change, and ecosystems really are responding to it."