A 1300-year Record of Penguin Populations at Ardley Island in the Antarctic, as Deduced from the Geochemical Data in the Ornithogenic Lake Sediments

We have reconstructed a continuous high-resolution penguin population record over the past ∼1300 years from the geochemical and 14C dating data in the ornithogenic lake sediments at Ardley Island in the Antarctic. The concentrations of F, P, Sr, Se, S, Cu, Zn, and Ca in the sediments are notably enriched and significantly correlated with each other, and they have a consistent pattern of change versus depth. These elements, as previously reported, are biomarkers of penguin droppings and population. Over the past ∼1300 years, the penguin population at Ardley Island, as measured by these biomarkers’ concentrations, has a decreasing trend, especially during the past century when the penguin population has dropped steeply. Compared with the paleoclimatic records and glacial advance and retreat history in the study area, the pronounced penguin population changes in the absence of human activities appear to be related to climatic changes. The steep decline of the penguin populations in the past century, however, seems to be caused by the abnormally warming climate in the Antarctic Peninsula.