Study shows growing population since end of last ice age
Global warming is expected to take a toll on some penguin populations, but other species could thrive — at least for a while.
Shrinking glaciers are opening new breeding areas for Adélie penguins in East Antarctica, perpetuating a 14,000-year trend of population increases, according to a new study published in the open access journal, BMC Evolutionary Biology.
Scientists estimate the Adélie population has grown 135-fold in the last 14,000 years, suggesting that current environmental conditions are more favorable for Adélie penguins than they were at the end of the last ice age.
But the effects of climate change are not uniform. Large regional variability means geographically distant populations of Adélie penguins will experience different environmental impacts, and the authors warn that in some parts of Antarctica the number of Adélie penguins is in decline.
“Shrinking glaciers appear to have been a key driver of population change over millennia for Adélie penguins in East Antarctica. Examining these birds’ responses to past climate change means we can begin to predict how well Adélie penguins will respond in the future,” said University of Tasmania researcher Jane Younger.
Younger said the study was aimed in part at trying to understand how climate change will affect penguin populations in the long term.
“The climate change that is underway right now is likely to have effects over thousands of years. We need to consider millennial-scale trends alongside contemporary data to forecast species’ abundance and distribution changes under future climate change scenarios,” Younger said.
East Antarctica is currently home to 30 percent of the global population of Adélie penguins, with an estimated abundance of 1.14 million breeding pairs. They are sensitive to changes in sea ice, the timing of sea ice retreat and the extent of glaciation, because they form breeding colonies on ice-free land along the Antarctic coastline and forage in the pack ice zone during the breeding season. An increase in sea ice can be detrimental to the birds, as adults have to forage for longer, reducing the frequency at which they can feed their chicks.
The researchers investigated the effect of climate change on Adélie penguins by using mitochondrial DNA from multiple living colonies, they sequenced 56 individuals from six colonies. The genetic data indicates past population dynamics, such as trends in abundance and responses to environmental changes across the East Antarctic region.
“Adequate food supplies must be available to sustain an expanding population of Adélie penguins. Whether this will be the case in the future remains to be seen, as the impacts of climate change on Adélie penguin prey species, such as Antarctic krill, are unclear at this time,” Younger said.