Periodic Reporting for period 2 - ANTSIE (ANTarctic Sea Ice Evolution from a novel biological archive)
Berichtszeitraum: 2021-12-01 bis 2023-05-31
The aim of the ANTSIE project is to reconstruct and assess the evolution of the sea-ice environment in the eastern Weddell Sea over the last ~40,000 years. This covers the time window before, during and after the Last Glacial Maximum (when sea ice extended thousands of km to the north of its current limit). Our aim is being achieved by addressing the following objectives:
1. tracking the use of sea-ice habitats by snow petrels and measuring the biochemical signature of foraging behaviour in stomach oils and tissues;
2. reconstructing snow petrel diet over time using biochemical and geochemical analyses of a network of well-dated snow petrel stomach-oil deposits;
3. inferring changes to conditions within the sea ice through time by combining objectives 1 and 2
4. assessing climate model simulations for sea-ice conditions through comparison with the data from objectives 1-3, and exploring the climatic impact of changes to sea ice over time.
Our main activities and results so far:
1. We successfully deployed GPS trackers on snow petrels during the 2021-2022 Antarctic field season, and collected stomach oil and feather samples for diet analysis. The fieldwork was based at the Princess Elisabeth Station, Antarctica, supported by the International Polar Foundation. We have been able to determine patterns of snow petrel foraging and links to sea ice distribution. Conference presentations include Honan, E.M. et al. (2022) World Seabird Conference, Cork, Ireland.
2. We retrieved 10 new snow petrel stomach-oil deposits from near Princess Elisabeth Station, Antarctica. The deposits have been radiocarbon dated, and chemical analyses have begun so that we can reconstruct diet through time. Conference presentations introducing the project include Cole, Y., Penny, C. et al. (2022) British Organic Geochemistry Society, Southampton, U.K.
3. We began chemical analyses on existing, radiocarbon-dated stomach-oil deposits from the Coats Land region, Antarctica. We have been able to detect changes in snow petrel diet occurring during the Holocene (the time since the Last Glacial Maximum). Conference presentations showing initial results include Stevenson, M.A. et al. (2022) British Organic Geochemistry Society, Southampton, U.K.
4. We published the results from a stomach-oil deposit in Dronning Maud Land. Here we combined bio- and geo-chemical analyses of the element content, fatty acid distributions, and stable isotope ratios to identify changes to snow petrel diet occurring over thousands of years during an interval of expanding sea ice before the Last Glacial Maximum (McClymont et al., 2022, Climate of the Past). We have presented this work at several conferences including the Geological Society of America (2021) and the Scientific Committee on Antarctic Research Open Science Meeting (2022).
Our interpretations of the changes in snow petrel diet through time are being refined by our new results of the tracking analysis, where we have been able to assess the foraging behaviour of the snow petrels in relation to environmental variables including sea ice. Our next step is to combine the tracking data with analysis of snow petrel stomach oils, to link the biochemical signals in the deposits directly to conditions in the sea ice environment.
Our initial results from the stomach-oil deposits show that for the first time we will be able to reconstruct long time series of snow petrel diet, which will extend through the Holocene and Last Glacial Maximum. We also have samples spanning the time interval immediately preceding the Last Glacial Maximum when there is other geological evidence for expanding Antarctic sea ice. We will be able to compare and contrast the results we generate from our western (Coats Land) and eastern (Sor Rondane) sites, to consider local variability in snow petrel diet over time. We expect that we will be able to draw on our tracking and modern diet sampling analysis to consider what these results mean in terms of changes in the sea-ice environment over time.
We will draw together our analysis of snow petrel diet through time with state-of-the-art climate modelling evidence for changes to sea ice in the same region. We will explore whether our data align with climate model outputs for sea-ice extent and sea-ice properties, and investigate the climatic impact of different sea ice scenarios for the Last Glacial Maximum and Holocene.