Monochrome penguins are well loved for its clumsy yet lovely moves and body shapes, and attract the attention of scientists who studies palaeogeography about Antarctic. The population history of the Adélie penguin (Pygoscelis adeliae) and its response to climatic and environmental changes have been widely studied in maritime Antarctica and several glacial refugia of Adélie penguins were dated back to the Last Glacial Maximum. However, the process of colony expansion during the subsequent glacial-interglacial transition was less well-documented.
The researchers at University of Science and Technology of China (USTC) of Chinese Academy of Sciences pushed the earliest record of Adélie penguin colonies in East Antarctic forward for around 6000 years. The study reported the oldest geological record of penguin colonization in East Antarctica, East Antarctica. The finding was published in Palaeogeography, Palaeochimatology, Palaeoecology.
Geochemical analysis of an ornithogenic core from Vestfold Hills suggested that penguins started colonizing the northern Vestfold Hills around 146,000 years before present (BP), the oldest geological record in East Antarctica on penguin occupation, and their population exhibited a broadly increasing trend thereafter.
This study deduced the deglaciation date, which is earlier than previous records, at the Vestfold Hills and reconstructed local penguin population history using geochemical proxies. Local deglaciation occurred around 15.6 kyr BP, based on a coarse-grained detrital layer, a date that is earlier than most of those reported in other studies from the same region.
Following the last glacial-interglacial transition, the Antarctica experienced the gradual emergence and expansion of ice-free areas, which supported the expansion of breeding sites of the Adélie penguin in the Antarctic. However, most geological evidence of penguin colonies in different areas exhibits discrepancy with the local records of deglaciation history, resulting in little understanding of the colonizing process of penguins following the deglaciation period.
The researchers adopted bio-typochemical elements of a lake sediment core from the Long Peninsula in the Vestfold Hills, East Antarctica as the proxy to identify the deglaciation sediment layer aged 15600 years BP (before present) and the penguin ornithogenic sediment layer aged 14600 years BP. Their results indicated that penguins colonized approximately 1000 years after the ice cap retreat, which followed by a consistent expansion of the population.
This suggested that ice retreat during glacial-interglacial transition is a major incentive of the growth of penguin population and the expansion of penguin colonies, which was likely to strongly affects the occupation history of breeding sites of seabirds in the polar regions.
The study initiated the investigations of reconstructing the time of penguin colonization in ice-free areas in the Antarctic, which delivers important objectives of searching for the sanctuary of penguin during the last glacial-interglacial transition and developing further insights into the process and principles of penguins’ migration to the surrounding regions in the Antarctic continent.
The study was supported by the Chinese Polar Environment Comprehensive Investigation & Assessment Programs, the International Cooperation in Polar Research and the Natural Science Foundation of China, the Australian Antarctic program via Australian Antarctic Science Projects. All field procedures were approved by the Australian Antarctic Animal Ethics Committee.
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