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Reconstructing Southern Ocean productivity and carbon cycle dynamics in the Neogene

A postgraduate research opportunity at the University of Otago.


Academic background
Host campus
Dr Christina Riesselman, Associate Professor Chris Moy


The Southern Ocean is responsible for 50 per cent of the global ocean uptake of carbon dioxide (CO2) produced by anthropogenic activities. The efficiency of the Southern Ocean carbon sink is partially driven by the biological pump, where phytoplankton blooms along the Antarctic Circumpolar Current consume CO2, then settle to the seafloor, locking this carbon away in thick sedimentary sequences. Despite the importance of the biological pump in the global carbon cycle, the Southern Ocean is a challenging environment; very few sediment cores have been collected from this important region and reconstructions of biological pump efficiency under warmer-than-present climates are rare.

In 2019, IODP Expedition 383 drilled two exceptional sites in the central South Pacific that are ideal to fill this gap. This project first seeks to determine how changes in primary production are linked to Southern Ocean climate signals two records are linked, by developing high resolution records of changes in diatom assemblage and biogenic silica in marine sediments that accumulated during past warm climate intervals, and interpreting this record in the context of scanning XRF and other data sets. Depending on candidate interests and background, complimentary data sets can also be developed, including carbon and nitrogen isotopes and concentrations and/or diatom-bound δ15N to evaluate nutrient utilization and water column structure, or the application of diatom transfer functions to develop a quantitative SST reconstruction.

This project is ideal for a student with an interest in climate reconstruction and experience developing and integrating micropaleontology and/or geochemistry data sets. Selection is contingent on receiving a competitive University of Otago Doctoral Scholarship.


Christina Riesselman