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The results of an international collaborative study by the Chinese University of Science and Technology reveal the habitat history of the oldest penguin breeding ground in the Ross Sea of Antarctica

2022/4/25     Viewed:    
The results of the international cooperative research of China University of Science and Technology reveal the source of the oldest penguin breeding ground in the Ross Sea of Antarctica: HKUST News Network

Recently, Professor Xie Zhouqing's team from the Department of Environmental Science and Engineering at the University of Science and Technology of China and Anhui Provincial Key Laboratory of Polar Environment and Global Change, together with Professor Carlo Baroni's team from the University of Pisa, Italy, have made new progress in the response of penguin population to climate change in the Holocene. The relevant research results are summarized as "The occupation history of the longest-dwelling Adelie penguin colony reflects Holocene climatic and. environmental changes in the Ross Sea, Antarctica, "was published online in Quaternary Science Reviews.

Penguins are typical Marine creatures in Antarctica and are very sensitive to climate changes. Penguins hunt in the sea, breed on land, and are located at the top of the food chain in the Southern Ocean. A series of climate and environmental factors play an important role in the life cycle of penguins, and affect the food structure/abundance and habitat suitability of penguins through physical, chemical and biological processes, and ultimately affect the prosperity and decline of penguin populations and distribution patterns. In recent decades, significant climate changes have been taking place in the Antarctic region, which have seriously affected penguin populations and habitat distribution. Observational data indicate that Adelie penguin populations on the Antarctic Peninsula have declined significantly, while their range is shrinking southward, and several breeding populations have disappeared completely. Simulation studies predict that if greenhouse gas emissions continue at the current rate, about 80% of emperor penguin colonies will be endangered by the end of the 21st century. And 70% of king penguins have been forced to move to new habitats or disappear.

Studies of the distribution of penguin breeding grounds over historical periods have shown that certain breeding grounds are better able to withstand environmental changes, acting as sanctuaries for species in adverse climatic conditions. Antarctica's Ross Sea is home to one-third of the world's breeding population of Adelie penguins, and unlike the Antarctic Peninsula, where numbers have declined significantly, the Ross Sea Adelie penguin has shown a steady increase. Genomic studies suggest that the Ross Sea may have been one of only two Antarctic sanctuaries for Adelie penguins during the last ice maximum, but geological evidence for early Holocene penguins is lacking. Since the Holocene, the distribution of penguin breeding sites in the Ross Sea has undergone great changes, with the abandonment of old breeding sites and the creation of new breeding sites. Enkersburg Island is the oldest known and the only breeding site that has existed continuously for 7,000 years, and it is likely to be one of the earliest landing sites of penguins since the ice Age. The reconstruction of the response of the penguin population to climate change and the analysis of the reasons for its long-term stable existence are crucial for understanding and predicting the sensitivity and migration of Antarctic penguin colonies under the background of future climate change.



FIG. 1 Adelie penguin breeding grounds on Enkersburg Island

To this end, relying on the Antarctic Victoria Land station under construction in China, the research group carried out detailed grid survey and sampling of abandoned penguin breeding grounds on Enkesburgh Island during the 34th, 35th and 36th Antarctic expeditions, and conducted 14C dating of a large number of penguin manure sediment profiles and residue samples obtained by accelerator mass spectrometry. The integrated study, combined with relevant samples and data obtained over the past 30 years by Professor Carlo Baroni's team at the University of Pisa, Italy (Figure 2), found that Adelie penguins first settled on the island in 8,600 years ago, the earliest breeding ground in the Ross Sea since the Holocene, pushing the time of penguin population persistence forward by 1,600 years. And about the same time as the local glaciers receded. Thanks to the open water and abundant food sources provided by the interglacial Lake of Terranova, penguins immediately landed and bred here after the ice retreated.



FIG. 2 Spatial and temporal distribution of abandoned penguin breeding grounds on Enkersburg Island


The research team proposed a method combining the age and area measurement of abandoned nests to systematically recover the changes in penguin population and nest migration since the Holocene. It was found that the population of Enkersburg Island generally increased between 7000-3000 years ago, reaching a peak in 5500-5000 and 4000-3500 years. After a brief decline in 3500-3000, penguin populations expanded significantly between 3000-1500, corresponding to the massive settlement abandonment of the southern Scott Coast. The Scott Coast of the Ross Sea was full of penguin breeding sites for 5-4,000 years ago, but was abandoned in a large scale for 3-2,000 years ago. There have been two opinions about the reasons for the abandonment for a long time: "cooling theory" and "warming theory". Previously, Xie Zhouqing's research team found key evidence in the penguin dung layer, suggesting that the expansion of regional sea ice under the cooling conditions of the "New ice Age" and the increase of wind and snow under the influence of local topography were the main reasons for the abandoned Scott Coast, which solved the long-debated "mystery of penguin disappearance". The evolution of penguin breeding sites in the Ross Sea during the historical period was systematically reconstructed (Figure 2) (Quaternary Science Reviews, 264, 2021). Based on this, the study proposes that the ice-free environment provided by the Interglacial lake of Terra Nova Bay enabled Enkesburg Island to receive migratory penguin populations from the Scott Coast during the period of near-shore sea ice expansion, resulting in a substantial increase in penguin numbers and becoming a valuable refuge for the regional penguin population. The paper notes that inshore sea ice in the Ross Sea has been increasing in recent decades, so areas with interglacial lakes, such as Enkesburgh Island, will play a more critical role in the continuation of penguin populations.

The first author of the paper is Yuexong Gao, a postdoctoral fellow in the Department of Environmental Science and Engineering, and Professor Zhou Qing Xie and Professor Carlo Baroni are co-corresponding authors. The research work has been funded by the National Natural Science Foundation, the Key research and development Program of the Ministry of Science and Technology, and the Italian National Antarctic Project. The Antarctic field expedition was supported by the Polar Expedition Office of the State Oceanic Administration.

The thesis links: https://doi.org/10.1016/j.quascirev.2022.107494



(Department of Environmental Science and Engineering, Department of Scientific Research)

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