Past penguin colony responses to explosive volcanism on the Antarctic Peninsula

Recent changes in penguin populations on the Antarctic Peninsula have been linked to a range of environmental variables, but few studies have considered the potentially devastating impact of explosive volcanic activity on penguin colonies. We used detailed biogeochemical analysis to track past penguin colony change over the last 8,500 years on Ardley Island, home to the Antarctic Peninsula’s largest breeding population of Gentoo penguins. The first sustained penguin colony was established on Ardley Island c. 6,700 years ago, pre-dating sub-fossil evidence of Peninsula-wide occupation by c. 1,000 years. The colony experienced five population ‘maxima’ during the Holocene. Overall, no consistent relationships with local or regional sea ice conditions, ocean or atmospheric temperatures were found, although the colony population maximum, c. 4,000–3,000 years ago, corresponds with multiple records of elevated temperatures across the region, and we link late Holocene colony decline, in part, to the onset of neoglacial conditions, c. 2,500 years ago. Instead, our main finding was that all five phases of penguin colony expansion occurred in the absence of significant volcanic activity, and that at least three of the phases were abruptly ended by large eruptions of the Deception Island volcano at c. 5.4, 4.2 and 2.9 cal ka BP. These resulted in near-complete local extinction of the colony with up to c. 1,000 years required for recovery.