Holocene environmental conditions in the coastal ocean off East Antarctica - evidence from the paleo-diet of snow petrels

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Reconstructions of past environmental conditions in the coastal ocean off East Antarctica are crucial to better understand processes of ocean - ice interaction. For the proposed project, stomach oil deposits of snow petrels (Pagodroma nivea) (Antarctic mumiyo) shall be used as a paleoenvironmental archive of Holocene sea-ice conditions in the coastal zone of the Southern Ocean. A multiproxy approach, combining inorganic, lipid (fatty acids) and isotope (δ13C and δ15N) analyses will be applied to infer past changes in snow petrel diet, which can be linked to environmental conditions in the foraging range of the birds, such as sea ice variability, polynya activity and primary production. The study area comprises a large sector of the East Antarctic coastline, ranging from Wilkes Land (Windmill Islands) to Mac Robertson Land (Framnes Mountains) and is not well-covered by sea-ice records from the coastal zone. At the same time, some outlet glacier systems along this part of the coastline are sensitive to ocean warming, highlighting the need for a better understanding of ocean - ice interaction under changing climatic conditions in these regions. The research questions that will be addressed with this project are, if changes in Holocene sea ice coverage in the coastal zone i) occurred consistently across the East Antarctic margin, ii) were associated with shifts in the position of oceanic fronts, such as the southern boundary of the Antarctic Circumpolar Current and iii) are correlated with the advance/retreat of the ice sheet margin and/or its outlet glacier systems. To extent the existing sample set, sampling of mumiyo deposits in un-glaciated coastal sites (Windmill Islands, Bunger Hills, Gaussberg and Vestfold Hills) is part of the proposed project. Field work will be conducted within the scope of the RV Polarstern expeditions PS140 (EASI 2) and PS141 (EASI 3) that are scheduled back-to-back for the austral summer season 2023/24.