Analysis of ancient penguin guano has revealed that volcanic eruptions, not climate change, almost wiped out an Antarctic sea bird colony three times, researchers have found.
There has long been speculation linking fluctuations in penguin populations over recent decades to climate change, but scientists studying a colony of gentoo penguins in Antarctica wanted to look back much further.
The team, led by the British Antarctic Survey, hit upon the idea of drilling core samples from ancient guano deposits, giving them a record going back 7,000 years.
The results, published in Nature this week, showed the penguins of the Ardley Island colony had been dramatically impacted by a nearby volcano at Deception Island.
Lead researcher Steve Roberts said the millennia-old droppings, collected from the bed of a lake on the island, still had an intense smell.
But more importantly, the sediment cores also contained clear layers of volcanic ash, while biogeochemical analysis of the droppings provided insights into the colony’s population over time.
‘On at least three occasions during the past 7,000 years, the penguin population… was almost completely wiped out locally after each of three large volcanic eruptions,’ Roberts said.
‘It took, on average, between 400 and 800 years for it to re-establish itself sustainably.’
The guano analysis found ‘no consistent relationships’ between climate conditions and the penguin population in the Ardley Island colony, which currently has about 5,000 of the birds.
Ppenguins have a gene called DSG1, which in humans is known to be involved in a dermatological disease characterised by thick skinThey are the epitome of survival against the odds, enduring some of the most hostile weather conditions on the planet on a continent that is almost completely barren. And last year, scientists gained a valuable insight into how penguins are able to cope with the extreme cold, high winds and months of darkness they experience in Antarctica.Genetic analysis of the genomes of two species of penguin – emperor penguins, the largest of the family, and their smaller cousins Adélie penguins – has revealed some of their secrets to survival. Researchers found that the penguins have a vast number of genes responsible for creating the raw material needed for feathers – proteins known as beta-keratins.They carry more genes for a particular type of beta keratin than any other bird and it is thought this is what allows them develop their thick plumage of short, stiff feathers that keep them warm.The densely packed and barbed feathers also trap air to keep them buoyant and remain waterproof while they are swimming, allowing them to reach speeds of up to 22 mph in some species.The scientists also discovered that penguins have a gene called DSG1, which in humans is known to be involved in a dermatological disease characterised by thick skin on the palms and feet. It believe these genes may help the penguins develop a uniquely thick skin compared to other birds.
British Antarctic Survey penguin ecologist Claire Waluda said the innovative technique could be used to examine how volcanoes had affected other colonies.
‘Changes in penguin populations on the Antarctic peninsula have been linked to climate variability and sea-ice changes, but the potentially devastating long-term impact of volcanic activity has not previously been considered,’ she said.
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