March of the penguins into peril

The entire population of Antarctica’s famous emperor penguins could fall by a third by the end of the century because of disappearing sea ice, putting them at risk of extinction, say researchers.

Writing in the journal Nature Climate Change, scientists from Woods Hole Oceanographic Institution in Massachusetts say their findings justify protecting emperor penguins under the Endangered Species Act – as the US already does for polar bears. They also call for marine reserves to be created to buffer the fish stocks penguins need to survive.

“The population is declining. Unless something changes to stop that, the population will go into extinction,” says Hal Caswell, one of the authors of the study.

As a top predator in Antarctica, penguins are mainly at risk from climate change, which is melting the sea ice. The loss of ice is reducing the supply of krill, the tiny, shrimp-like crustaceans that populate the Southern Ocean and are the emperor penguins’ main food source. Young krill feed off algae living in the sea ice. When the ice goes, so do the krill.

Changes in the ice around Antarctica may – in the short term – boost some of the emperor penguin populations, especially along the Ross Sea, the researchers say. Sea ice off the western coast of Antarctica has been on the increase, because of wind conditions and the break-up of glaciers.

But by 2100, all 45 known emperor penguin colonies of Antarctica will be on the decline because of loss of sea ice. Those located on the coasts of the eastern Weddell Sea and the western Indian Ocean will show the sharpest drops. Nine colonies are projected to be “quasi-extinct”, the researchers say.

Other studies have raised the threat to emperor penguins under climate change, suggesting the ordinarily hardy animals, which grow to more than a metre high, are susceptible to rising heat. Smaller penguins such as the chinstrap and Adelie are also at risk.

Researchers from the University of Minnesota have suggested some emperor penguin colonies might be able to move location and so be better equipped to adapt to changing ice conditions than previously thought. But the Woods Hole researchers say their study was the first to forecast a population decline across all of Antarctica.

It also suggests there was little scope for penguins to adapt to the changing ice conditions. The researchers say the findings call for urgent measures to help the penguins survive – such as legal protection and the creation of marine reserves off Antarctica.

“Implementing a marine protected area in the Ross Sea could help buy time to avoid extinction and to put in place needed conservation and greenhouse gas mitigation strategies,” Stephanie Jenouvrier, lead author and a scientist at Woods Hole, said in a statement.

A marine reserve would potentially put large areas of ocean off-limits to fishing – reducing the pressure on krill stocks and giving the penguin a better chance of survival, says Andrea Kavanagh, director of global penguin conservation for the Pew Charitable Trusts.

“Given this new research, and what we already know about global temperatures warming and the changing climate, one of the things we should do immediately is put a marine reserve in place so we can make sure that we are not fishing in areas where the penguins need to forage for food,” she says. “It is one way of eliminating one more threat to the penguins.” – Guardian News & Media

Emperor penguin , climate change