Profiling the southern ocean’s microbial community


The Southern Ocean plays an important role in Earth’s climate, storing more heat and carbon dioxide (CO2) than any other ocean region. However, this capacity of the global ocean to absorb CO2 is actually limited by the Southern Ocean because phytoplankton – the microscopic plants living in surface waters that convert CO2 to organic carbon through photosynthesis – do not fully consume the macronutrients (nitrogen and phosphorus) supplied to Southern Ocean surface waters. While this is generally thought to result from a combination of iron and light limitation, the role of phytoplankton, bacterial, and zooplankton (i.e., “microbial”) diversity is less well understood.

We seek to understand how microbial community composition affects organic carbon export in the Southern Ocean, and how this changes with changing nitrogen source. Using a combination of cutting-edge chemical, biological, and computation techniques, we aim to answer the following questions regarding the microbial community in the open Southern Ocean: Who is there? What are they doing? Why are they doing it? What are the implications for Antarctic nitrogen cycling, ecosystem function, and atmospheric CO2 absorption, today and in a warming world? This work has implications for South Africa’s Oceans Economy, as Antarctic waters currently support globally-significant fisheries, as well as for the management of vulnerable ecosystems.


Principal Investigator (PI)

Sarah E. Fawcett 

Department of Oceanography, University of Cape Town, South Africa


A multi-disciplinary, multi-resolution approach to understanding nutrient cycling and microbial diversity in changing Subantarctic ecosystems


Principal institution / country

  • Cape Peninsula University of Technology (South Africa)
  • Department of Environmental Affairs (South Africa)
  • Nelson Mandela Metropolitan University (South Africa)
  • Princeton University (United States of America)
  • Rhodes University (South Africa)
  • South African Environmental Observation Network