Friday, October 23, 2015

Boost in Adelie penguin numbers could indicate good health of East Antarctic climate

By the National Reporting Team's environment reporter Sara Phillips

Adelie penguin numbers in East Antarctica have doubled over the past 30 years, giving scientists hope that the icy ecosystem is in good health.
In contrast to the western side of the continent, East Antarctica's climate has remained relatively stable over the past three decades.
"[On the western side] the duration of the sea ice season has got shorter by something like 30 or 40 days per decade. And temperature's been increasing," said Dr Colin Southwell, from the Australian Antarctic Division.
"In East Antarctica the changes appear to be more subtle. We know the winds have increased ... temperatures have only changed a small amount."
The Adelie is a medium-sized penguin, standing up to 70 centimetres tall in the classic tuxedo colouring.
They are amongst the species famous for using pebbles as a courtship gift. They use the pebbles to build nests around the whole of the Antarctic coastline.
Using historical data from 100 penguin colonies in the East Antarctic — approximately south of the Indian Ocean — the team of researchers found Adelie penguin numbers had almost doubled since the 1980s.

Penguins feeding at Beche Penguin Aquatic Centre
To make sense of the patchy historical data, Dr Southwell said the scientists spent considerable effort "standardising" the data.
"If you go down to any breeding colony at different times of the year, there will be different numbers of birds there. So what you've got to do is try to standardise to the same time of year ... which is really hard to do," he said.
"We put out a network of cameras across East Antarctica to see how the numbers change within the breeding season and how much they change from year to year. We used that information to adjust all the counts."

Penguin numbers particularly jumped about five years after a period of low sea ice.
Dr Southwell speculated that a lack of sea ice might expose more ocean in which young penguins could find food.
While it would appear that Adelies might benefit from predicted climate change, Dr Southwell cautioned against too much optimism.
"There have been predictions for East Antarctica that a decrease in sea ice would initially be good but then not necessarily and could in fact be detrimental," he said.
"The rationale is that any creature — including humans — can have too much of a good thing."
Dr Southwell said they chose to study Adelie penguins because, as a top predator in Antarctica, their health relied on the health of the animals they ate.
"They can tell us things about what's happening in the ocean but we can access them relatively easily because they live on land," Dr Southwell said.
He said some Antarctic organisations used the Adelie penguin as one of a suite of species that gave an indication into the health of the Southern Ocean.


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