Ornithogenic soils in the lake margin reveal the most recent Adélie penguin recolonization in Cape Royds, Antarctica

Abstract

Ice-free areas hold the most biologically active and diverse ecosystems in Antarctica, in which penguins play an important role. As the climate conditions changed in the past, penguins migrated among different breeding sites, making their populations recorded in a certain area a key index to explore the interactions between the local environment and ecological processes. Two 210Pb-dated ornithogenic soil profiles encoded MR1 and MR2 are used in this study to recover the time of Adélie penguin (Pygoscelis adeliae) recolonization in Cape Royds of Ross Island, and their recent population change based on the element assemblage related to penguin guano, including Cu, Cd, Hg, P, S, Se, and Zn. It is revealed by both profiles that abundant penguins reentered this ice-free area at about 1820 to 1830, corresponding to the onset of a continuous warming. We found the reconstructed penguin population change pattern of MR1 in the lake margin in good agreement with the census and monitoring data since the late 1950s, and the pattern was subjected to environmental factors including temperature, sea ice, and polynyas. Our results showed that the ornithogenic soils in the lake margin can reflect the size of the penguin colony, and bridge the gap between long-term records and modern census, laying the basis for assessing the future penguin population in response to the drastically changing climate due to anthropogenic influence.