University of Tasmania, Australia

Isotopic and faunal analysis of Chatham Rise sediment-trap and sediment-core foraminifera.

Level: PhD Project

We will examine stable isotopic and shell-flux signals in foraminifera from the Sub-Antarctic Southern Ocean over seasonal through glacial-interglacial timescales. We will determine isotopic and flux seasonality, using shells δ18O and seasonal flux variability.  In addition we can detect the isotopic signature of anthropogenic CO2 in foraminifera shell carbon isotopes (δ13C) from moorings in the Sub-Antarctic Southern Ocean (previously documented by King and Howard, 2004). We will compare the carbon and oxygen isotopes to infer foraminiferal habitat information.

This research will deliver information about the living habitats of Sub-Antarctic foraminifera and thus their relative vulnerabilities to acidification under conditions of continuing carbon uptake but modified by seasonal and interannual variability (e.g. McNeil and Matear, 2008). The faunal analysis of interannual variability in foraminiferal populations and flux will allow us to assess the extent to which their contribution to carbon flux (mediated by their “ballasting” effect) is changing and whether the multivariate structure of the assemblages is changing due to the differential vulnerability and sensitivity of different species. This question is key to understanding how climate impacts like acidification may change the structure of ecosystems by creating “winners” and “losers.”

King, A.L. and Howard, W.R. 2004. Planktonic foraminiferal δ13C records from Southern Ocean sediment traps: New estimates of the oceanic Suess effect. Global Biogeochemical Cycles 18: GB2007.

McNeil, B.I. and Matear, R.J. 2008. Southern Ocean acidification: A tipping point at 450-ppm atmospheric CO2. Proceedings of the National Academy of Sciences 105:18860–18864.

Nominal Coordinator: Donna Roberts

Supervisors: Dr Donna Roberts (ACE CRC-Australia), Dr Will Howard (OCS-Australia) and Dr Mike Gagan (ANU-Australia).