In May of the year 2000 a chunk of ice measuring 4,250 square miles (11,000 square kilometers) broke free from Antarctica’s Ross Ice Shelf. The size of the New England state of Connecticut, this tabular berg, which is flat unlike the jagged and pointy icebergs that break off glaciers, was the largest floating thing on earth.
You may wonder what impact a berg that size can have on the animals that live near it. In 2002 and 2003 and again in 2005 the gigantic berg broke into smaller pieces, forming a dam that kept the pack ice from following its normal summer path out to the open sea.
Phytoplankton, the primary food of krill, which are in turn food for the rest of the Antarctic food web, need open water and light to reproduce. The ice dam and all the pack ice caught behind it blocked out the light and caused a 40% decline in plankton. Less plankton meant fewer krill, which meant less food for penguins. Not only did penguins have less food, they had to swim further to get it as they had to swim around this massive iceberg.
What would you do if your home grocery stores suddenly had not enough food? Might you consider moving? Some penguins made that choice and abandoned their rookeries.
Source:
Shwartz, M. (2002). Satellite imagery shows how icebergs affect Antarctica’s food chain, Stanford Report, April 24.