Earth Sciences
Welcome to Stellenbosch University

​​​​​​​​​​​​​​Prof Susanne Fietzdsc_5725.jpg

Associate Professor

Department of Earth Sciences,
Stellenbosch University, South Africa
tel +27-21-808-3117
email: sfietz at

2022/2023 Postd​​oc advert: 2022-12 StellU-postdoc-mercury.pdf

ORCID: 0000-0003-0896-8385
ResearcherID: A-8695-2012
Scopus: 6508296863
Loop: 567300

​​ Research theme: Biogeochemistry in aquatic systems, Environmental Geochemistry, Paleoenvironment, Global Change

Research profile:

My research aims to study modern aquatic systems and sedimentary archives as well as sedimentation processes to help interpretation. This approach provides essential information on past and present environmental conditions for those predicting future local and global changes.

We currently have a major ongoing project on the Southern Ocean: Studying biogeochemical cycles to help evaluate potential tools for climate mitigation. Almost all life on Earth depends somehow on photosynthesis fueled by energy from the sun. Growth, which translates into carbon fixation and thus atmospheric CO2 reduction, however, further depends on the availability of macro- and trace nutrients. One of the most famous quotes of early awareness of climate changes and potential mitigation strategies is from John Martin (Moss Landing Marine Laboratories, US, 1988) "Give me half a ship load of iron...I could give you an ice age". In 2013, there is still no scientific consensus, what the consequences of this type of geo-engineering are. We aim to investigate how phytoplankton, acclimatized to current conditions of light and trace metal availability, will most likely respond to predicted future global warming and thus ocean structure changes. 

Dr ​Fietz seeks students for the following topics

      • Methylmercury in the Southern Ocean. This project is only available to students wishing to pursue at least into M.Sc. A strong interest in interdisciplinary and international work is requested for these projects as it is a collaborative work with Mediterranean Institute of Oceanography, Marseille, France.
      • Southern African dust aerosols: sources, trajectories and impact. This involves analyising their general geochemistry and trace metal composition, and their dissolution kinetics, which leads to study their potential fertilisation and/or inhibitory effects after deposition. A student with an interest in atmospheric sciences is required for this project. 
      • Algae community composition and adaptation, driving factors and the impact on biogeochemical cycles (including carbon and its impact on the global climate), and/or on marine sediment formation (siliceous ooze, vs. calcareous ooze, for instance). A strong interest in interdisciplinary work, including biological sciences, is requested for this project. 
      • This project includes a component on the toxic and/or inhibitory impacts of selected trace metals on primary producers
      • Another field of studies relates to paleo-geochemistry and climate reconstructions and establishing or improving tools for paleo-reconstructions. We use organic molecules to reconstruct the climate of the past, understand natural variability to disentangle the current anthropogenic impact. This, in turn, helps to improve the projections of the future. 
      • In collaboration with Iziko Museum (Dr Eugene Bergh), a project on Miocene to Recent biostratigraphy and marine palaeoenvironments of South Africa is offered. A part of this is also to investigate if we can record the Plio-Pleistocene marine extinction on our margin. 
      • We also seek support for our study on river pollution and the impact of rainfall events on Western Cape's river water quality. A study conducted in 2016-2018 has revealed interesting trends in the Eerste River and Lourens River and we will extend this study to other rivers of the Western Cape..​

Projects offered in 2023

1. "A year of CO2 concentrations in South Africa" - in collaboration with Dr Warren Joubert, SAWS.  This project will look at CO2 concentrations measured at Cape Point, put them in context with previous years, decades and the long-time geological past. The expected project outcome includes outreach activities and and support for the ​development of a translational document for stakeholders.

2. "Atmospheric mercury at Cape Point and ocean south of South Africa", with Dr Lynwill Martin (SAWS); This project is a continuation of a project started in 2022. It looks at changes in the gaseous mercury concentrations and speciation and tests what drives the changes. The expected project outcome includes outreach activities and support for the development of a translational document for stakeholders.

3. "Impact of southern African dust ​of natural and industrial origin on human and ecosystem health"; This project will collect dust samples in the Western Cape and test the load, mineral characteristics, geochemical composition. The expected project outcome includes outreach activities and support for the development of a translational document for stakeholders.

4. "Testing enhanced weathering as terrestrial Carbon Dioxide Removal strategy in southern Africa"; The simplified idea is to add rock dust (ground rock) to southern African soils​ in laboratory, column experiments to test the carbon removal potential. ​

Ongoing or accomplished PhD, MSc and Honours theses at Stellenbosch University:

2023, Victor Mugabe: "Effect of Cu, Cd and Zn on a South African West Coast Phytoplankton Community"

2023, Isabella Braithwaite: "Potential biotoxicity of dust in Saldanha Bay, South Africa"

2022 + 2023-2024 Kereemang Gaoaaga: "Real-time PM2.5 (air quality) measur​ements in Stellenbosch, South Africa" & "Geochemical characteristics of PM2.5 in residential areas, South Africa" 

2022, Ezelna Germeshuisen: "Atmospheric mercury concentation and speciation at Cape Point, South Africa", with Dr Lynwill Martin (SAWS)

2022, Zara Samsodien: "Trace metals in stack emissions of the research vessel SA Agulhas II" 

2022, Gege Ozengiwe: "Impact of zinc on the phytoplankton Nannochloropsis spp."

2022-2023, Liam Quinlan: "​Southern Ocean phytoplankton community structure and potential impact of climate change"

2022-2023, Jared Walsh: "Assessing and refining Plio-Pleistocene foraminifera fossil assemblages from the Orange Shelf of South Africa", with Dr Eugene Bergh (Iziko)

2021-2022Jayde Bromwhich: "Summer and winter phytoplankton composition in the Atlantic adn Indian sectors of the Southern Ocean"

2021-2022 + 2023-2025, Emtia Wium: "Impact of potentially toxic trace metals on phytoplankton in waters south of South Africa"​​ & "Impact of Metals on Phytoplankton in oceans around southern African​"

2021, Liam Quinlan: "Assessing benefits for on-campus phytoplankton pigment analysis"

2020, Ireland Allisaib: "Natural vs. Anthropogenic dust characteristics and potential impacts"

2019/2020 Sunnette Vos (Uni Pretoria): "Effects of hydrocarbon contamination on virus-host interactions​"

2019, Warrick Daws: "Pollution in Saldanha Bay, Western Cape"​

2019, Herman Boock: "Impact of metal contaminants on marine microorganisms"

2018 + 2019/2020, Raya Stavreva: "Paleo-proxies in sediments of Lake Baikal, Siberia" & "Constraining Barium as paleoproxy"

2016 + 2017/2018 + 2019-2022, Johan Viljoen: “Phytoplankton community composition in the Southern Ocean”

2015 + 2016/2017 + 2018-2022, Ismael Kangueehi: “Composition and impact of Southern African dust”

2018, Sean Househam: "Metal load in water and sediments of False Bay, Western Cape" 

2018, Dylan McLeod: "Nutrient retention in streams of the Western Cape"

2018/2019, Zandria Jordaan: "Driving factors of del13POC in the Atlantic Southern Ocean" 

2018-2022, Asmita Singh: "​​Southern Ocean phytoplankton ecophysiological response to iron availability​" 

2017/2018, Ian Weir: "Testing the Silicate Leakage Hypothesis in the Southern Ocean"

2016 + 2017/2018, Reuben Lazarus: "Urban river pollution in the Western Cape, South Africa"

2017, Jodie Pieterse: "Bacterial and archael community composition in the Atlantic sector of the​ Southern Ocean".

2017, Zahné Pienaar: "changes in deltaC13 across the Southern Ocean and in iron fertilisation experiments"

2017, Patrick Prestele: "Reconstruction of paleo-temperature in Mfabeni peats, SA"

2017, Marcel Labuschagne: "Characterisation of aerosols in the Western Cape, SA"

2017, Gustav Rezelman: "Self-purification potential of Kuilsriver and Stenbras River, Western Cape, SA"

2015, Mari Scott: “Photosynthetic response of Southern Ocean phytoplankton to dust bulk fertilization”

2015, Gillian Trollope: “Establishing a new paleotemperature proxy in the Southern Ocean”

2013-2015, Natasha van Horsten: "Photosynthetic response of Southern Ocean phytoplankton under iron and light limitations"

2013, Ryno Roux: "The applicability of Hydroxy Isoprenoidal -GDGTs as a possible molecular paleoclimate proxy in the Southern Ocean"

List of publications:


  • Shalileh, FGheibzadeh, MSLloyd, JRFietz, SShahbani Zahiri, HZolfaghari Emameh, REvolutionary analysis and quality assessment of ζ-carbonic anhydrase sequences from environmental microbiomeJ Basic Microbiol2023114
  • Singh A, Fietz S, Thomalla SJ, Sanchez N, Ardelan, Moreau S, Kauko HM, Fransson A, Chierici M, Samanta, Mtshali, Roychoudhury AN, Ryan-Keogh TJ. (2023) Absence of photophysiological response to iron addition in autumn phytoplankton in the Antarctic sea-ice zone. Biogeosciences 20, 3073-3091.​​
  • Fietz S., Baker A., Miller C.S. , Naafs B.D.A., Peterse F., Finch J., Humphries M., Schefuß E, Roychoudhury A.N., Routh J. (2023) Terrestrial temperature evolution of southern Africa during the Late Pleistocene and Holocene: evidence from the Mfabeni Peatland.​ Quaternary Science Reviews​299, 107870

newsClimatologists outline their agenda for Africa in 2023. University World News, Africa edition, Jan 2023.


  • Singh A., Thomalla S., Fietz S., Ryan-Keogh T. (2022) Spatial and temporal variability of phytoplankton photophysiology in the Atlantic Southern Ocean. F​​ront. Mar. Sci. 9:912856. ​​​

  • DATA SET: Fietz, Susanne; Baker, Andrea; Miller, Charlotte S; Naafs, Bernhard David A; Peterse, Francien; Finch, Jemma M; Humphries, Marc; Roychoudhury, Alakendra; Routh, Joyanto; Schefuß, Enno (2021): Late Pleistocene to Holocene GDGT data in Mfabeni peat, South Africa. PANGAEA,
  • DATA SET: Viljoen, Johannes J; Fietz, Susanne (2021): Surface summer phytoplankton pigment concentrations measured by HPLC during the SANAE-56 cruise in the Atlantic Southern Ocean between December 2016 and February 2017. PANGAEA,
  • Cloete R., J.C. Loock, N.R. van Horsten, J-L. Menzel Barraqueta, S. Fietz, T.N. Mtshali, H. Planquette, M.I. García-Ibáñez, A.N. Roychoudhury (2021). Winter dissolved and particulate zinc in the Indian Sector of the Southern Ocean: Distribution and relation to major nutrients (GEOTRACES GIpr07 transect). Marine Chemistry 236, #104031​.​ https://doi.o​rg/10.1016/j.marchem.2021.104031
  • Cloete R, Loock JC, van Horsten N, Fietz S, Mtshali TN,  Planquette H, Roychoudhury AN (2021). Winter biogeochemical cycling of dissolved and particulate cadmium in the Indian sector of the Southern Ocean (GEOTRACES GIpr07 transect). Front. Mar. Sci. 8:656321.​
  • Kalpana MS, Routh J, Fietz S, Lone MA, and Mangini A (2021) Sources, Distribution and Paleoenvironmental Application of Fatty Acids in Speleothem Deposits From Krem Mawmluh, Northeast India. Front. Earth Sci. 9:687376.​​​
  • Farmer J, Hertzberg J, Cardinal D, Fietz S, Hendry K, Jaccard S, Paytan A, Rafter P, Ren H, Somes C, Sutton J., GEOTRACES-PAGES Biological Productivity Working Group Members. Assessment of C, N and Si isotopes as tracers of past ocean nutrient and carbon cycling. Global Biogeochemical Cycles, e2020GB006775 (2021),
  • also see the companion paper: Horner et al. Bioactive trace metals and their isotopes  as paleoproductivity proxies: An assessment using GEOTRACES-era data. Global Biogeochemical Cycles, e2020GB006814 (2021).
  • Weir I, Fawcett S, Smith S, Walker D, Bornmann T, Fietz S*. Winter biogenic silica and diatom distributions in the Indian Sector of the Southern Ocean. Deep Sea Research Part I, 103421 (2020).
  • Fietz S*, Ho SL, Huguet C, Archaeal membrane lipid-based paleothermometry for applications in polar oceans, Oceanography 33, 104-114,​.
  • Viljoen J, Weir I, Fietz S*, Cloete R, Loock J,​ Philibert R, Roychoudhury AN. Links between phytoplankton community composition and trace metal distribution in the surface waters of the Atlantic Southern Ocean. Frontiers in Marine Science, 6:295,
  • Grand MM, Laes-Huon A, Fietz S, Resing JA, Obata H, Luther GW, Tagliabue A, Achterberg EP, Middag R, Tovar-Sanchez A, Bowie A (2019) Developing autonomous observing systems for micronutrient trace metals. Frontiers in Marine Science 6:35,
  • Cloete R, Loock JC, Mtshali TN, Fietz S, Roychoudhury​ AN. (2019)​ Winter and summer distributions of Copper, Zinc and Nickel along the International GEOTRACES section GIPY05: Insights into deep winter mixing.​ Chemical Geology 511, 342-357
  • Viljoen JJ, Philibert R, van Horsten N, Mtshali TN, Roychoudhury A, Thomalla S, Fietz S(2018)​ Response of phytoplankton in growth, community structure and photophysiology to iron and light addition in the Polar Frontal and Antarctic Waters of the Southern Ocean. Deep Sea research I, 141, 118-129​
  • Huguet C, Routh J, Fietz S, Mahjoor AL, et al. (2018) Temperature and Monsoon Tango in a Tropical Stalagmite: Last Glacial-Interglacial Climate Dynamics​. Scientific Reports, 8, 5386,  doi:10.1038/s41598-018-23606-w​​
  • Fietz S, Ho S-L, Huguet C, Rosell-Melé A, Martínez-García A (2016​). Appraising GDGT-based seawater temperature indices in the Southern Ocean. Organic Geochemistry, 102C, 93-105.
  • Baker AR, Landing WM , Bucciarelli E, Cheize M, Fietz S, Hayes CT, Kadko D, Morton PL , Rogan N, Sarthou G, Shelley RU , Shi Z, Shiller A, van Hulten MMP (2016). Trace Element and Isotope Deposition across the Air – Sea Interface: Progress and Research Needs. Philosophical Transactions of the Royal Society A.374, 20160190.​
​up to 2015​