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

重建东南极洲沿海海域过去的环境条件对于更好地理解海洋-冰相互作用的过程至关重要。本课题以南大洋海岸全新世海冰条件的古环境档案——雪海燕（Pagodroma nivea） （Antarctic mumiyo）应使用胃油沉积为研究对象。结合无机、脂质（脂肪酸）和同位素（δ13C和δ15N）分析的多代理方法将被应用于推断雪海燕饮食的过去变化，这可能与鸟类觅食范围内的环境条件有关，如海冰变异性、多冰区活动和初级生产。研究区域包括南极东部海岸线的一大部分，从威尔克斯地（风车群岛）到麦克罗伯逊地（弗雷姆尼斯山脉），并没有很好地覆盖沿海地区的海冰记录。与此同时，沿这部分海岸线的一些出口冰川系统对海洋变暖很敏感，这突出表明需要更好地了解这些地区气候条件变化下的海洋-冰相互作用。该项目将解决的研究问题是，如果沿海地区全新世海冰覆盖的变化i)在整个南极东部边缘持续发生，ii)与海洋锋位置的变化有关，如南极环极流的南部边界，iii)与冰盖边缘和/或其出口冰川系统的进退有关。为了扩大现有的样本集，对未被冰川覆盖的沿海地区（风车岛、邦格山、高斯伯格山和韦斯特福尔山）的mumiyo沉积物进行采样是拟议项目的一部分。现场工作将在RV极地探险PS140 （EASI 2）和PS141 （EASI 3）的范围内进行，这两个项目计划在2023/24年的南方夏季背靠背进行。

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.