The Great Antarctic Melt May Benefit These Penguins
We all think of penguins as ice-loving creatures. But melting Antarctic ice could benefit, somewhat, one particular penguin species of the southern continent.
Adélie penguins live on the sea ice all around the coast of Antarctica most of the year. They breed, however, only on ice-free land. According to a paper published this week in BMC Evolutionary Biology, climate change will result in the penguins having more ice-free land on which to breed in East Antarctica, home to about 30 percent of the species.
That may allow those populations of Adélies to increase, even though the species overall is on the decline right now, owing to losses in Antarctic sea ice.
Lead author Jane Younger said the results of the study—which used DNA to calculate 22,000 years of population trends—surprised her. “I had expected that after the end of the ice age the Adélie penguin population would increase only when sea ice conditions became similar to what they are today,” said Younger, a biologist at the University of Tasmania.
Instead, she found that population increases took place when glaciers and ice sheets retreated, which “would have opened up more ice-free ground suitable for nesting,” she explained. The Adélie penguin population increased 135 times after ice-age glaciers retreated, according to the study.
Human-caused global warming is expected to create glacial retreats in Antarctica very similar to those the continent experienced after the last ice age. If that comes about, Younger said, the population of Adélie penguins in East Antarctica could grow.
There is a crucial difference between the ancient and contemporary warming periods, however. Temperatures are rising 10 times faster than what happened during the last “glacial-interglacial transition,” Younger said, so “it is going to be a lot more difficult for species to adapt in time to survive.”
Another factor is food. Younger noted that Antarctic krill—the minute marine shrimp that Adélie penguins and most other Southern Ocean predators rely on—are poorly studied and are being overfished in some regions of the Southern Ocean. This means there may not be enough krill in the future to feed a growing penguin population.
“Krill is commercially fished at the moment and is also likely to be negatively impacted by climate change,” Younger said. “But the effects of climate change on krill are not that well understood yet.”
Both this study and the team’s earlier research into Emperor penguins revealed that penguin populations that live around the Ross Sea—a section of the Southern Ocean that juts into Antarctica’s southern coastline—are genetically distinct, probably because the area provided shelter for them during the last ice age. “If penguins have survived there consistently, then that is probably an important place to protect,” Younger said.
In 2013, the U.S. and New Zealand proposed establishing a Marine Protected Area in the Ross Sea, but it was blocked last year by China and Russia.
Younger believes her team’s studies show we should be planning for the future of Antarctica in terms of thousands of years, not decades. Considering things on this millennial scale, she said, will help to accurately forecast the challenges and changes that species like Adélie penguins will face and help us protect them for centuries to come.