Reconstructing Antarctic sea ice environments from new seabird archives
Antarctic sea ice is an important part of the climate system, because it affects the transfer of heat and carbon between the oceans and the atmosphere, and supports unique ecosystems which are intricately linked to cycles of sea ice advance and retreat. But sea ice is also a very challenging environment to investigate, because it can be difficult to access or to observe, and its complexity makes it difficult to model. The result is that there is uncertainty about how Antarctic sea ice and its ecosystems will respond to a warming climate.
Now, a team of researchers in the Department of Geography is taking a new approach to generating sea-ice histories, drawing on an important relationship between sea ice and the Antarctic seabird the snow petrel (Pagodroma nivea). The snow petrels feed in open waters associated with the sea ice, then return to their nests on mountains poking out above the ice sheet (nunataks), sustained by their energy-rich stomach oil which is used to feed chicks but also spat in defense.
Photo credit: Ewan Wakefield
What is the link between Petrels and climate?
The team is working on deposits of stomach oils which have accumulated over thousands of years at the nesting sites. The deposits record changes to snow petrel diet (e.g. how much fish or krill they ate), and the team aims to use these signals to better understand past changes to the sea ice ecosystem. A recent fieldwork campaign fitted GPS trackers on snow petrels and collected diet samples, to understand how modern environmental variables affect the composition of the stomach oils. Almost 100 deposits are being geochemically analysed to reconstruct diet reconstructions, with a focus on the eastern Weddell Sea. Genetic analysis will explore snow petrel population histories and prey contributions to their diet. Modelling of both the physical sea ice system and prey distributions through time will also enable the project to consider past, present, and future ecosystem changes linked to Antarctic sea ice.