Reconstructing late Holocene summer sea-ice variability in the eastern Weddell Sea

To date, there are few records of Holocene changes in sea ice in the south-eastern Weddell Sea, which limits our understanding of how sea ice has interacted with climate in this sector of the Southern Ocean. Here, we present a multi-proxy analysis of a snow petrel stomach-oil deposit that records occupation history and dietary fluctuations from ~1800 to 800 calibrated (cal.) yr bp . Lipid biomarkers (fatty acids (FAs), sterols and alkanols), bulk stable isotopes (δ 13 C and δ 15 N) and trace elements show distinct dietary shifts, which are linked to centennial-scale changes in summer sea-ice extent. From ~1730 to 1370 cal. yr bp , foraging in pelagic waters near the edge of the sea-ice pack is suggested by low nest occupation rates and Antarctic krill contributions to the diet. From ~1370 to ~1180 cal. yr bp , an increase in nest occupation and a fish-dominated diet reflect foraging within open water (polynyas) during a period of more extensive summer sea ice. A decrease in nest occupation after ~1180 cal. yr bp is attributed to local sea-ice readvance, resulting in reduced access to open water, impeding foraging success. Our results highlight the use of multi-proxy geochemical records from snow petrel stomach-oil deposits to reconstruct seasonal sea-ice fluctuations in the Weddell Sea and their interactions with late Holocene climate records.