Lots of ice, lots of penguins – and vice versa | Polarjournal
It is becoming increasingly difficult for Adélie penguins to find sufficient food due to climate change, as krill migrate to colder regions. Only along the east side of the Antarctic Peninsula, populations are still stable. Photo: Julia Hager

Temperatures on the Antarctic Peninsula are rising rapidly – five times faster than the global average. For the Adélie penguins breeding there, warming poses an enormous threat. To study the effects of global climate change on penguin colonies, scientists from Stony Brook University, New York, organized an expedition to the peninsula earlier this year aboard the Greenpeace ship Arctic Sunrise.

Adélie penguins living on the Antarctic Peninsula are choosier than their counterparts elsewhere in Antarctica. While Adélies on the peninsula feed only on krill, they also eat fish in other regions of Antarctica. However, krill only live where there is enough sea ice. This is no longer the case in the west of the peninsula due to severe warming, which is why Adélie penguin populations have declined by 90 percent in some areas along the west coast.

On the eastern side of the Antarctic Peninsula, however, in the Weddell Sea, the situation is more favourable. Sea ice extent there is still large – thanks to an oceanic eddy that keeps pack ice rotating in the Weddell Sea for years. Therefore, colonies on the east coast have remained stable over the past decade. According to researchers, colonies on Seymour Island, Devil Island, Vortex Island and Cockburn Island in the north of the peninsula have roughly the same population size as during the last survey. Their findings suggest that the Weddell Sea could be an important refuge for wildlife from the worst effects of the climate crisis.

The researchers studied Adélie penguin colonies on Seymour Island, Devil Island, Vortex Island, Cockburn Island and Paulet Island. Map: Julia Hager/GoogleEarth

These findings also underscore the urgent need to protect and preserve the Weddell Sea while it still has an intact and functioning ecosystem. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) proposed a huge protected area almost ten years ago, which has not yet been implemented.

“The Weddell Sea is hardly immune to climate change, but it appears that Adélie penguins breeding in the area are spared the worst threats to populations that are declining so rapidly on the warming western side of the Antarctic Peninsula,” said Dr. Heather Lynch, professor of ecology and evolution in the College of Arts and Sciences at Stony Brook University and leader of the expedition. “Our knowledge of the biology of this inhospitable landscape grows year by year, but everything we learn points to its value for conservation.”

For the first time, scientists at Stony Brook University also discovered a colony of gentoo penguins on the eastern side of the Antarctic Peninsula on Andersson Island. So far south it was too cold for Gentoo penguins until some time ago. “Mapping these remote island groups will give us a better understanding of how penguins in this region are responding to rapid climate change,” Lynch said. “As expected, we find gentoo penguins almost everywhere we look – further evidence that climate change is drastically altering biodiversity here on the Antarctic Peninsula.”

One of the southernmost records for Gentoo penguins is Andersson Island. Meanwhile, conditions are favorable for them there. Photo: Julia Hager

On the west coast, gentoo penguins, attracted by the warmer conditions, have now taken over the former breeding sites of the Adélies. “They eat everything, they breed everywhere,” Lynch told The New York Times. “I consider them the pests of the peninsula.”

Dr. Lynch, who directs the Lynch Lab for Quantitative Ecology at Stony Brook University and holds the first endowed chair in ecology and evolution at the Institute for Advanced Computational Science (IACS), works primarily with satellite imagery to study the penguins, but also conducts expeditions to the colonies. During the expedition earlier this year, she and her colleagues counted Adélie penguin chicks by hand and with the help of drones. According to the report, 21,500 chicks live at Penguin Point on Seymour Island alone.

According to Lynch, however, the stable populations do not mean that climate change is not occurring in the Weddell Sea. “It just means that the Weddell Sea, because of its oceanography, continues to be cold and icy and just the kind of place these Adélies need to live,” she says.

Julia Hager, PolarJournal

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