The Spirit of Mawson - Australasian Antarctic Expedition 2013 - 2014

Australasian Antarctic Expedition

Mammals

The Southern Ocean and Antarctic systems offer remarkable natural experimental models for studying disrupted ecosystems. The long-term stability of the Antarctic has led to the development of a tightly coupled marine trophic structure, but the recent synergy between climate induced and anthropogenic influences (fisheries) has seen some regions undergo environmental change. Mammals are likely to be susceptible to the potential effects of anthropogenic pollutants and global warming. Unlike many other predators in the region, many of the seals (leopard, crabeater, Ross and Weddell seals) were never directly harvested by humans; so that their population trajectories track the impacts of biological and environmental changes in this ecosystem. By investigating changes in the food web, particularly foraging and spatial patterns of seal populations, we can compare with historic samples and changes seen in the West Antarctic.

The research program

  1. On the AAE 2013-2014 we set out south to discover whether there has been a change at the top of the Antarctic food web among the seal populations since the original expedition.
  2. On the AAE 2013-2014 we undertook to map the stable isotopic signatures in seals to investigate whether there has been a change in diet over time.
  3. On the AAE 2013-2014 we wanted to find out more about the singing behaviour* of the seals and how we can use their songs to learn more about the seals themselves.

* listen to Sea Leopard song recorded on the expedition on Soundcloud.

Research Papers

Tropical forcing of increased Southern Ocean climate variability revealed by a 140-year subantarctic temperature reconstruction

Turney, C.S.M., Fogwill, C.J., Palmer, J.G., van Sebille, E., Thomas, Z., McGlone, M., Richardson, S., Wilmshurst, J.M., Fenwick, P., Zunz, V., Goosse, H., Wilson, K.J., Carter, L., Lipson, M., Jones, R.T., Harsch, M., Clark, G., Marzinelli, E., Rogers, T., Rainsley, E., Ciasto, L., Waterman, S., Thomas, E.R., Visbeck, M.

The Southern Ocean plays a fundamental role in global climate but suffers from a dearth of observational data. As the Australasian Antarctic Expedition 2013-2014 we have developed the first annually-resolved temperature record using trees from subantarctic southwest Pacific (52˚-54˚S) to extend the climate record back to 1870. With modeling we show today’s high climate variability became established in the ~1940s and likely driven by an atmospheric signal that originated in the tropical Pacific. Our results suggest that the influence of contemporary equatorial Pacific temperatures may now be a permanent feature across the mid- to high latitudes of the Southern Hemisphere, with substantial impacts on seabird and mammal populations.

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