Emperor Penguins

Krill decline threatens penguins

Survey of Antarctic marine life reveals some worrying news

A massive new survey of Antarctic marine life has revealed an alarming decline in krill populations, due to melting sea ice, which threatens the future survival of the penguins which depend on them.

The findings were presented at a meeting of the American Association for the Advancement of Science (AAAS) by Marine Biologist Huw Griffiths from British Antarctic Survey (BAS).

The Census of Antarctic Marine Life (CAML), which began in 2005, reveals that populations of krill, an essential food for penguins, whales and seals, are declining as the sea-ice cover decreases, allowing the much smaller copepod, another type of crustacean to become dominant.

The ultimate effect of this is a shift in the balance of the food web which will favour predators of the smaller copepods, such as jellyfish, and will not be eaten by penguins and other higher predators. The reduction in sea-ice will also affect those penguin species that breed on the ice.

Addressing the AAAS meeting, Griffiths said: “The polar regions are amongst the fastest warming places on Earth and predictions suggest that in the future we’ll see warming sea surface temperatures, rising ocean acidification and decreasing winter sea ice - all of which have a direct effect on marine life.

“Marine animals spent millions of years adapting to the freezing, stable conditions of the Antarctic waters and they are highly sensitive to change. If species are unable to move or adapt to new conditions they could ultimately die out.”

He fears that penguins, seabirds and whales which are all used to catching large items of prey will suffer while creatures like jellyfish will have more food in the form of the smaller prey and will do better in this warmer environment. Many species of small invertebrates, fish and crabs that are presently unable to live in the -2°C temperatures in the Antarctica waters might start soon start to appear.