- Study of polar coccolithophore macroevolutionary trends for the last 5 Myr;
- Phytoplankton productivity during past warm intervals as analogues for the future;
- Quantification of bias in coccolithophore proxies due to carbonate dissolution.
The Southern Ocean stores 40% of anthropogenic CO2 and regulates thermal exchange between the lower latitudes and the ice-sheets of the Antarctic continent. The extent of Southern Ocean sea ice regulates gas exchange between the surface ocean and atmosphere as well as influencing ocean stratification, phytoplankton primary productivity and the renewal of deep waters. To understand the coupling between climate, the cryosphere and Southern Ocean biogeochemistry – and their combined strong feedback on external climate forcing – requires realisations of this complex system across a range of future-analogue conditions.
International Ocean Discovery program (IODP) Expedition 383 (Lamy et al., 2019) drilled a series of cores from the Pacific sector of the Southern Ocean to explore glacial-interglacial changes in marine ecosystems and biogeochemistry. Studies from the Atlantic sector of the Southern Ocean (Martinez-Gacia et al., 2009, Flores et al., 2012) show increased phytoplankton productivity in glacial climates in the Subantarctic Zone, but decreases in the Antarctic Zone south of the Polar Front. It is however, difficult to extrapolate from these studies to the larger Pacific sector of the Southern Ocean, because Patagonian dust fluxes may play a significant role in regional iron fertilization of phytoplankton in the Atlantic sector but not the Pacific (Flores et al., 2012).
IODP Expedition 383 sites constitute the first drill cores in the Subantarctic Pacific Southern Ocean extending through the Pleistocene and back into the Pliocene. These cores provide the basis for the generation of robust data to test the extent that processes active in the Atlantic sector can be translated to the Pacific sector. In turn, this will allow the construction of a global picture of the Southern Ocean’s role in nutrient distribution, biogenic export production and global biogeochemistry during past warm climate intervals.
Results of this research will be closely linked to co-ordinated Antarctic IODP Expeditions to the Ross Sea (374), Amundsen Sea (379), and Scotia Sea (382), that targeted successions proximal to the Antarctic ice sheets. New data from Expedition 383 will provide constraints on Southern Ocean biogeochemistry that can be integrated with an understanding of ice sheet dynamics provided by these other Expeditions.
HostUniversity of Birmingham
- Climate and Environmental Sustainability
- Organisms and Ecosystems
- Dr Tom Dunkley Jones, University of Birmingham
- Dr Mariem Saavedra, University of Birmingham
The project will focus on coccolith (calcareous nannofossil) variations since the Pliocene and will use an array of techniques:
- Micropaleontological techniques, such as quantitative determination of coccolithophore assemblages down to species level using light microscope, assessment of coccolith preservation in Scanning Electron Microscope; morphometrics and coccolith mass determination by transmitted optical microscopy.
- Geochemical techniques, such as coccolith chemistry (trace metals – Sr/Ca – and stable isotopes – δ18O, δ13C) based indicators of coccolithophore growth and productivity.
- Data analyses techniques including time series and spectral analyses of the large dataset that will be generated. This will also include combining and comparing with other relevant datasets generated by other scientists (e.g., oxygen and carbon isotopes measured on foraminifera, alkenones, diatoms, XRF-core scanner measurements).
Training and skills
The student will receive detailed training in sample preparation techniques and calcareous nannofossil taxonomy from Supervisors Dr Dunkley Jones and Dr Saavedra-Pellitero (who sailed in IODP Exp. 383 and contributed to the establishment of the age models on board). By the end of the PhD is expected to be an expert on Plio-Pleistocene nannofossil biostratigraphy at high latitudes, and productivity estimates using independent proxies, with transferrable skills to both research and industrial communities. Data analyses using statistical approaches will provide the student with a valuable tool to interpret the generated data, essential to draw well-supported conclusions.
Partners and collaboration
International collaboration with different renowned institutions will be a part of this project. For instance, Alfred Wegener Institute (Germany), Otago University (New Zealand), University of Massachusetts-Amherst (USA), University of California, Santa Cruz (USA) and Università degli Studi di Milano-Bicocca (Italy). A close collaboration with Dr Elisa Malinverno, as expert in cocolithophore biogeography and biostratigraphy in the Southern Ocean, is envisaged. She will provide additional coccolithophore datasets and guidance in the interpretation of the data.
Applications need to be submitted via the University of Birmingham postgraduate portal, https://sits.bham.ac.uk/lpages/LES068.htm, by midnight 11.01.2021. Please first check whether the primary supervisor is within Geography, Earth and Environmental Sciences, or in Biosciences, and click on the corresponding PhD program on the application page.
This application should include
- a brief cover letter, CV, and the contact details for at least two referees
- a CENTA application form
- the supervisor and title of the project you are applying for under the Research Information section of the application form.
Referee’s will be invited to submit their references once you submit your application, but we strongly encourage applicants to ensure referees are aware of your submission and expecting a reference request from us. Students are also encouraged to visit and explore the additional information available on the CENTA website.
Training sample preparation and coccolith light microscope counts, as well as training in Scanning Electron Microscope, morphometric analyses and coccolith mass determination.
Training in coccolith geochemical analyses. International conference and possibility of a short research stay aborad.
Compilation of data (including additional independent datasets: e.g., geochemistry, sedimentology, etc) data processing.
Flores et al. 2012, https://doi.org/10.3389/fmicb.2012.00233
Lamy et al. 2019, https://doi.org/10.14379/iodp.pr.383.2019
Martínez-Garcia et al. 2009, https://doi.org/10.1029/2008PA001657
Ronge et al. 2016, https://doi.org/10.1038/ncomms11487
Saavedra-Pellitero et al. 2017, https://doi.org/10.1002/2017PA003156
This project does not require fieldwork or other practical activities so should be minimally impacted by any travel restrictions caused by the pandemic. Access to microfossil preparation facilities as well as microscopy and geochemical (IRMS, ICP-MS/OES) facilities are the main requirements and both local and national facilities have now reopened during the past months. Interruptions to this project are therefore not foreseen in the medium term.