Antarctic penguin colony repeatedly decimated by volcanic eruptions
April 11, 2017
Gentoo penguins climbing slopes to the nesting colony on Ardley Island. Credit: Stephen Roberts
One of the largest colonies of gentoo
penguins in Antarctica was decimated by volcanic eruptions several times
during the last 7,000 years according to a new study. An international
team of researchers, led by British Antarctic Survey (BAS), studied
ancient penguin guano and found the colony came close to extinction
several times due to ash fall from the nearby Deception Island volcano.
Their results are published this week in Nature Communications.
Ardley
Island, near the Antarctic Peninsula, is currently home to a population
of around 5,000 pairs of gentoo penguins. Using new chemical analyses of
penguin guano extracted in sediment cores from a lake on the island,
the researchers unraveled the history of the penguin colony. Climate
conditions around Ardley Island have been generally favourable for
penguins over the last 7,000 years and the team had expected the local
population to show minor fluctuations in response to changes in climate
or sea ice. The surprising result was that the nearby Deception Island
volcano had a far greater impact than originally anticipated.
Lead author Dr Steve Roberts from BAS says: "When we first examined the sediment cores
we were struck by the intense smell of the guano in some layers and we
could also clearly see the volcanic ash layers from nearby Deception
Island. By measuring the sediment chemistry, we were able to estimate
the population numbers throughout the period and see how penguins were
affected by the eruptions. On at least three occasions during the past
7,000 years, the penguin population was similar in magnitude to today,
but was almost completely wiped out locally after each of three large volcanic eruptions. It took, on average, between 400 and 800 years for it to re-establish itself sustainably."
Volcanic ash layers in lake sediment cores extracted from
Kiteschee Lake on Fildes Peninsula. The ash layers shown are associated
with comparatively small eruptions from Deception Island in the last c.
2000-3000 years. The largest eruptions …moreDr
Claire Waluda, penguin ecologist from BAS says: "This study reveals the
severe impact volcanic eruptions can have on penguins, and just how
difficult it can be for a colony to fully recover. An eruption can bury
penguin chicks in abrasive and toxic ash, and whilst the adults can swim
away, the chicks may be too young to survive in the freezing waters.
Suitable nesting sites can also be buried, and may remain uninhabitable
for hundreds of years."
The techniques developed in this study will help scientists to
reconstruct past changes in colony size and potentially predict how
other penguin populations may be affected elsewhere. For example, the
chinstrap penguins on Zavodovski Island, which were disturbed by
eruptions from the Mt Curry volcano in 2016.
Waluda continues: "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."
More information:
Past penguin colony responses to explosive volcanism on the Antarctic Peninsula, Nature Communications (2017). nature.com/articles/doi:10.1038/ncomms14914
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