Extinction Warning for King Penguins As Sea Temperatures Rise
King penguin populations could be threatened with extinction as a result of climate change, as warming sea temperatures reduce the amount of food available to them, scientists have warned.
A study of a colony of the seabirds breeding on an island in the northern reaches of Antarctica found warmer sea surface temperatures reduced both the survival and breeding success of the penguins.
The researchers, writing in the Proceedings of the National Academy of Science, said there was a 9 per cent decline in adult survival for each 0.26C of warming.
This puts the king penguin- which has a current population of some two million breeding pairs – under “heavy extinction risk” under the current global warming predictions which are around 0.2C per decade on top of a 0.74C rise last century, they warned.
The sub-antarctic seabirds, which are the second-largest penguins after the emperor, feed on fish and squid which in turn eat plankton that are sensitive to variations in the sea surface temperature.
High temperatures can reduce the growth rate of plankton and larvae fish which then have a knock-on effect all the way up the food chain.
Less abundant food sources close to the colony could also jeopardise the survival of newly- hatched chicks, as parents are forced to forage further afield and stay away from the nests for longer.
Such trips could also prevent the adult bird’s ability to recover its fuel reserves once chicks have left the nest as it fasts while incubating eggs, the scientists said.
The study also found adult survival was reduced two years after higher sea-surface temperatures were recorded further away from the colony.
This is because king penguins spend long periods of the winter at sea foraging at the edge of the pack ice, where low levels of sea- ice cover can have a negative impact on their prey.
About two thirds of the world’s king penguin population nest on the Crozet Archipelago, where the scientists conducted their nine- year study on Possession Island.
The birds have a 12-month breeding cycle – extending into the time of the year when marine resources are at their lowest – which means even small environmental changes can have a big impact.
They are also at the top of the food chain and forage both near where they breed and further out to sea, means they are also a “shining example” of how species depending on the Southern Ocean may fare as global warming continues, the scientists said.
“In line with the last Intergovernmental Panel on Climate Change estimation of a linear increasing trend of 0.74C of global surface temperature during the last century and a further warming of around 0.2C per decade for the next two decades, the warming of the Southern Ocean certainly represents a major threat for penguins.
“Some other seabird communities in Antarctica might be affected by such a cascade of effects of Southern Ocean warming,” the scientists led by Yvon Le Maho at the CNRS Institut Pluridisciplinaire Hubert Curien, Strasbourg, said.
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