Late Holocene Adélie penguin population dynamics at Zolotov Island, Vestfold Hills, Antarctica

Abstract

We inferred late Holocene Adelie penguin occupation history and population dynamics on Zolotov Island, Vestfold Hills, Antarctica, using geochemical data from a dated ornithogenic sediment core (ZOL4). Radiocarbon dates on fossil penguin bones in the core indicate that Adelie penguins occupied the island as early as 1,800 years before present (yr BP), following the retreat of the Sorsdal glacier. This occupation began ~1,200 years later than that observed at Ardley Island and King George Island, in the South Shetland Islands. Phosphorus was identified as the most indicative bio-element for penguin guano in core ZOL4, and was used to infer past penguin population dynamics. Around 1,800 years ago, the Adelie penguin populations at both Zolotov Island and Ardley Island increased rapidly and reached their highest levels ~1,000 yr BP. For the past ~900 years, the penguin populations at Zolotov Island have shown a general rising trend, with fluctuations, while those at Ardley Island have shown a moderate decreasing trend. The Adelie penguin populations at both Ardley Island and Zolotov Island showed a clear decline ~300 years ago, which we interpret as a response to the Little Ice Age, or a neoglacial cooling event.