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A group of adelie penguins, Pygoscelis adeliae, stand on an ice floe.

Adélie penguins, seen here on an ice floe, are in decline because retreating sea ice and commercial fishing have reduced the penguins' main food source: krill.

PHOTOGRAPH BY BILL CURTSINGER, NATIONAL GEOGRAPHIC CREATIVE

Jane J. Lee

National Geographic

Published June 12, 2014

Despite their pot-bellied profile and waddling gait, Antarctic penguins have weathered the challenges of one of the harshest climates on Earth for millennia. Three of those species—the Adélie, chinstrap, and gentoo—were also able to tolerate, if not flourish under, a warming event that came as ice sheets began to shrink, says a new study.

They were climate change "winners," the authors write. About 15,000 to 20,000 years ago, the retreating ice exposed expanses of bare ground that the penguins could build nests on, allowing them to expand their populations.

This historical perspective is helping researchers to understand the penguins' current situation in western Antarctica. (See "West Antarctic Glaciers Collapsing, Adding to Sea-Level Rise.")

The warming that researchers are now measuring on the Antarctic Peninsula is approaching the limits of what these penguin species experienced in the past, says Gemma Clucas, a doctoral student at the University of Southampton in the United Kingdom and lead author of the new paper. "We're seeing a very different response [from them now.]"

Genetic analysis of 249 gentoo, 166 chinstrap, and 122 Adélie penguins showed that all three populations expanded after the last glacial maximum—when the ice sheets were at their greatest extent—the researchers report today in the journal Scientific Reports. But only gentoo penguins seem to be holding their own against current warming trends in the western Antarctic. The other two species are in decline.

Too Much and Not Enough

"You can have too little ice and too much ice, and both of these are bad," says Jefferson Hinke, an ecologist with the U.S. National Oceanic and Atmospheric Administration's Southwest Fisheries Science Center in La Jolla, California.

In the past, the problem was a lack of real estate. During the last glacial maximum, there was 100 percent more ice in the sea surrounding Antarctica, severely restricting access to the ocean, which penguins depend on for food. Glaciers also covered the bare ground, where they lay their eggs and raise their young. It wasn't until the ice started melting that the penguin populations began to do better.

"Now we have too little ice," says Hinke, who was not involved in the study, "and the ecological consequences of that are that species like Adélie and chinstraps aren't doing too well." However, unlike the past, the problem for penguins now is a dwindling food supply.

Adélie and chinstrap penguins rely mainly on krill, which has been declining due to retreating sea ice, which the shrimplike animals need to grow. Commercial fishing for krill, along with a resurgence of whales that prey on the tiny animals, have further reduced krill populations.  Gentoo penguins are likely doing better because they have a more flexible diet, which includes fish and some squid, in addition to krill. (See also "Penguin Numbers Plummeting—Whales Partly to Blame?")

Nothing Lasts Forever

"These species are a lot more robust than we sometimes give them credit for," says Heather Lynch, a population ecologist at Stony Brook University in New York who contributed data to the study. Researchers worry when species are forced to shift their ranges, she says, but this paper shows that these penguin species can come through those changes.

However, "there have been reversals of fortune in the past," Lynch says. The Adélie and chinstrap penguins are evidence of that. Even though the gentoo penguins seem to be doing OK now, "there's no guarantee that that will last forever."

Follow Jane J. Lee on Twitter.

6 comments
Karin Holloway
Karin Holloway

Belief has nothing to do with measuring sea ice. We've just been told that this may benefit southerly colonies, although its hurting northwestern ones. Krill populations may be cyclical but as with the Blue Footed Booby -anchovies-krill ecosystem, the krills' return might be too late. The birds will be too old to mate.

Jim Steele
Jim Steele

Only along the western peninsula have penguin numbers dropped. Elsewhere they are still growing. Wind blowing ice against the coast caused the largest loss in one colony because it made their trip to open water to long. The latest research also shows that krill populations have rebounded in response to the changing Pacific Decadal Oscillation which affects upwelling that controls the food web.


This article is nothing but more climate fear mongering!!! 

Paul M.
Paul M.

It's not a crisis as long as it's only "believers" saying; "proven" and "100%" and not science itself.

If science can't be certain, you remaining "believers" can only be branded as fear mongers for history to judge. 
Deny that! 
Who's the neocon?

Todd Brown
Todd Brown

Do a little research and you will see that penguins used to eat fish.  But when whaling decimated the whale population there was an overabundance of krill and the penguins switched from fish to krill as the main source of calories in their diet.  Now that whaling has been reduced, (not eliminated, don't try to tell me the Japanese are doing real science with their whaling), the whales are eating more krill, the krill population has been reduced but the penguins have not switched back to eating fish.

So is man to blame for the falling numbers of penguins, or is he to blame for the explosion in penguin population when we killed off almost all of the whales?  And now the oceans cannot support the larger penguin population and the growing whale population.  What is the true sustainable penguin population?

ALFRED MOSES
ALFRED MOSES

@Paul M. As with so many deniers the science is ignored by requiring more, more, more proof.  If, the situation at hand is not proof enough then there will never be enough proof of climate change, until there is no ice in the Arctic or  Antarctica and Kansas will be beach front property. 

C. Dufour
C. Dufour

@Todd Brown But not all species are equally dependant on the sam species. Krill are highly seasonal and are most prolific in the anoretic summer. Many species of penguin coincide this event with their breeding season. fish are eaten in the winter months.

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