EGU2020-19394, updated on 12 Jun 2020
https://doi.org/10.5194/egusphere-egu2020-19394
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Cocccolithophore contribution to carbonate export to the deep sea in the Australian-New Zealand sector of the subantarctic Southern Ocean

Andres Rigual-Hernandez1, Thomas W. Trull2,3, Scott D. Nodder4, José A. Flores1, Helen Bostock5, Fátima Abrantes6,7, Ruth S. Eriksen2,8, Francisco J. Sierro1, Diana M. Davies2,3, Anne-Marie Ballegeer9, Miguel A. Fuertes9, Alba González Lanchas1, and Lisa C. Northcote4
Andres Rigual-Hernandez et al.
  • 1Área de Paleontología, Departamento de Geología, Universidad de Salamanca, 37008 Salamanca, Spain (arigual@usal.es)
  • 2CSIRO Oceans and Atmosphere Flagship, Hobart, Tasmania 7001, Australia
  • 3Antarctic Climate and Ecosystems Cooperative Research Centre, University of Tasmania, Hobart, Tasmania 7001, Australia
  • 4National Institute of Water and Atmospheric Research, Wellington 6021, New Zealand
  • 5University of Queensland, Brisbane, Queensland 4072, Australia
  • 6Portuguese Institute for Sea and Atmosphere (IPMA), Divisão de Geologia Marinha (DivGM), Rua Alferedo Magalhães Ramalho 6, Lisboa, Portugal
  • 7CCMAR, Centro de Ciências do Mar, Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal
  • 8Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, Tasmania 7001, Australia
  • 9Departamento de Didáctica de las Matemáticas y de las Ciencias Experimentales, Universidad de Salamanca, 37008 Salamanca, Spain.

Coccolithophores are ubiquitous marine unicellular algae belonging to the Class Prymnesiophyceae, division Haptophyta. They are distinct from other phytoplankton groups in their capacity to produce minute calcite platelets (termed coccoliths) with which they cover their cells. During the Cretaceous and throughout the Cenozoic era, pelagic sedimentation of carbonate was largely controlled by coccolithophores as evidenced by their major contribution to deep-sea oozes and chalks. In the modern Southern Ocean, coccolithophores represent an important component of the phytoplankton communities and carbon cycle. However, their contribution to total Particulate Inorganic Carbon (PIC) for large regions of the Southern Ocean remains undocumented.

Here we report the Particulate Inorganic Carbon (PIC) and coccolithophore fluxes collected over a year by sediment traps placed at two sites of the subantarctic Southern Ocean. We present coccolith mass estimates of the most abundant coccolithophore species and quantitatively partition annual PIC fluxes amongst heterotrophic calcifying plankton and coccolithophores. Our results reveal that coccolithophores account for approximately half of the annual PIC export in the subantarctic Southern Ocean. Moreover, in contrast to satellite estimations, that mainly reflect coccospheres and detached coccoliths of Emiliania huxleyi, less abundant but larger species make the largest contribution to CaCO3. Lastly, comparison of our data with previous studies suggest that projected environmental change in the Southern Ocean may result in a decline of coccolithophore PIC production and export.

 

How to cite: Rigual-Hernandez, A., Trull, T. W., Nodder, S. D., Flores, J. A., Bostock, H., Abrantes, F., Eriksen, R. S., Sierro, F. J., Davies, D. M., Ballegeer, A.-M., Fuertes, M. A., González Lanchas, A., and Northcote, L. C.: Cocccolithophore contribution to carbonate export to the deep sea in the Australian-New Zealand sector of the subantarctic Southern Ocean, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19394, https://doi.org/10.5194/egusphere-egu2020-19394, 2020