A terrestrial archive of marine environmental conditions in Antarctica – evidence from snow petrel stomach oil deposits

In the Southern Ocean microfossil records from marine sediments indicate large shifts in species assemblages and nutrient cycling in response to changing climatic conditions and sea-ice extent during the Late Pleistocene and Holocene. While the northern latitudes of the Southern Ocean are relatively well covered by sedimentary records, little is known about past changes in sea-ice coverage and the abundance and activity of polynyas, and associated ecological changes in near coastal areas off East Antarctica. In that regard, deposits of fossil stomach oil of snow petrels (Pagodroma nivea) (also termed Antarctic mumiyo) are unique records that can be found in un-glaciated terrestrial areas of Antarctica. The stomach oil is of dietary origin and contains information on the composition of snow petrel food, which is linked to environmental conditions in the marine foraging range of the birds, such as summer sea-ice variability and productivity in the coastal ocean. Our geochemical data (lipids, stable isotopes, inorganic composition) suggests that this information is preserved to some extent in the fossil stomach oil deposits. Radiocarbon analysis shows that the material comprises records of hundreds to thousands of years, with the oldest deposits being older than 50 thousand years. Stratigraphic analysis combined with geochemical data and correlation with coastal sediment records, makes the deposits a novel archive of past marine environmental conditions, biogeochemical cycling, and food web structure.