Decline in penguin levels linked to climate change

CLIMATE change effects on food sources may have contributed to a halving of penguin populations in Antarctica.

Researchers found that populations of Adelie and chinstrap penguins in the West Antarctic Peninsula (WAP) and Scotia Sea had fallen by 50% in the last 30 years.

The decline was directly related to a huge reduction in numbers of the penguins’ main prey, shrimp-like krill.

Krill density had dropped by as much as 80%, due to heightened competition from marine mammals and rising temperatures, said the scientists.

The findings challenge the theory that melting sea ice reduced the populations of Adelie penguins while benefiting chinstrap penguins. Rather, the evidence suggests that both species of penguin are suffering.

The researchers wrote in the journal, Proceedings of the National Academy of Sciences: “There now is overwhelming evidence to confirm significant declines in both Adelie and chinstrap penguin populations throughout the WAP and Scotia Sea.”

Climate-driven “bottom-up” changes to the ecosystem in the past three decades had probably been a key factor in reducing numbers of krill, the researchers said.

They warned that krill fishery operations were poised to expand, further threatening the penguin populations.