23 Apr 2020

23 Apr 2020

Review status: this preprint is currently under review for the journal BG.

Fatty acid carbon isotopes: a new indicator of marine Antarctic paleoproductivity?

Kate Ashley1, James Bendle1, Xavier Crosta2, Johan Etourneau2,3, Philippine Campagne2,4, Harry Gilchrist1, Uthmaan Ibraheem1, Sarah Greene1, Sabine Schmidt2, Yvette Eley1, and Guillaume Massé4,5 Kate Ashley et al.
  • 1School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
  • 2EPOC, UMR-CNRS 5805, Université de Bordeaux, 33615 Pessac, France
  • 3EPHE/PSL Research University, 75014 Paris, France
  • 4LOCEAN, UMR CNRS/UPCM/IRD/MNHN 7159, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris, France
  • 5TAKUVIK, UMI 3376 UL/CNRS, Université Laval, 1045 avenue de la Médecine, Quebec City, Quebec, Canada G1V 0A6

Abstract. The Antarctic coastal zone is an area of high primary productivity, particularly within coastal polynyas where large phytoplankton blooms and drawdown of CO2 occur. Reconstruction of historical primary productivity changes, and the associated driving factors, could provide baseline insights on the role of these areas as sinks for atmospheric CO2, especially in the context of projected changes in coastal Antarctic sea ice. Here we investigate the potential for using carbon isotopes (δ13C) of fatty acids in marine sediments as a proxy for primary productivity. We use a highly resolved sediment core from off the coast of Adélie Land spanning the last ~ 400 years and monitor changes in the concentrations and δ13C of fatty acids along with other proxy data from the same core. We discuss the different possible drivers of their variability and argue that C24 fatty acid δ13C predominantly reflects phytoplankton productivity in open water environments, while C18 fatty acid δ13C reflects productivity in the marginal ice zone. These new proxies have implications for better understanding carbon cycle dynamics in the Antarctica coastal zone in future paleoclimate studies.

Kate Ashley et al.

Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

Kate Ashley et al.

Kate Ashley et al.


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Short summary
We explore the potential for the use of carbon isotopes of algal fatty acid as a new proxy for past primary productivity in Antarctic coastal zones. Coastal polynyas are hotspots of primary productivity and are known to drawdown CO2 from the atmosphere. Reconstructions of past productivity changes could provide a baseline for the role of these areas as sinks for atmospheric CO2.