Penguins and vegetations on Ardley Island, Antarctica: evolution in the past 2,400 years

The impact of penguins on vegetation cover is a frequently documented but not fully explained phenomenon, especially over geological time scales. To address this we collected two ornithogenic sediment cores from Ardley Island, Antarctica, and reconstructed historic variations of penguin population and different vegetations by using biomarkers fecal sterols and n-alkanols in the cores. The three major types of vegetations in the colony, namely coprophilic algae, moss and lichen, exhibited quite different trends, in concert with fluctuations in the penguin populations: a moderate penguin population is favorable for coprophilic algae and mosses, while lichen abundances decreased whenever penguin population increased, and vice versa. Cholestanol and alkanols biomarkers, in combination with bioelements, provided integrated information about the 2,400-year evolution of the penguin colony: historical penguins and vegetation populations, their fluctuations, and their interactions.