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

恢复南极东部沿海海域过去的环境状况对于更好地了解海冰相互作用的过程至关重要。在拟议的项目中，将利用雪燕(Pagodroma Nivea)(南极mumiyo)的胃油沉积作为南大洋沿海地区全新世海冰状况的古环境档案。结合无机、脂肪(脂肪酸)和同位素(δ13C和δ15N)分析的多指标方法将被用于推断雪燕饮食过去的变化，这些变化可能与鸟类觅食范围内的环境条件有关，如海冰变异性、冰盖活动和初级生产力。研究区域包括东南极海岸线的一大部分，范围从威尔克斯岛(风车群岛)到麦克罗伯逊地(Framnes Mountain)，没有被沿海地区的海冰记录很好地覆盖。与此同时，沿这部分海岸线的一些出海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区域气候条件变化下的海冰相互作用。这一项目将涉及的研究问题是：如果全新世海冰覆盖率的变化：1)整个东南极边缘持续发生；2)与海洋锋面位置的变化有关，例如南极绕极洋流的南部边界；3)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，对非冰川沿海地区(风车群岛、邦格山、高斯伯格和维斯特福尔德山)的木米洋沉积物进行采样是拟议项目的一部分。实地工作将在计划于2023/24年南半球夏季连续进行的PS140(EASI 2)和PS141(EASI 3)房车极地探险队的范围内进行。

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.