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Biogeosciences An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/bg-2019-19
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2019-19
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 13 Feb 2019

Research article | 13 Feb 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Biogeosciences (BG).

Temporal variability in foraminiferal morphology and geochemistry at the West Antarctic Peninsula: a sediment trap study

Anna Mikis1, Katharine R. Hendry2, Jennifer Pike1, Daniela N. Schmidt2, Kirsty M. Edgar2,a, Victoria Peck3, Frank J. C. Peeters4, Melanie J. Leng5, Michael P. Meredith3, Chloe L. Todd2, Sharon Stammerjohn6, and Hugh Ducklow7 Anna Mikis et al.
  • 1School of Earth and Ocean Sciences, Cardiff University, Main Building, Cardiff, CF10 3AT, UK
  • 2School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen’s Road, Bristol, BS8 1RJ, UK
  • 3British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, UK
  • 4Department of Earth Sciences, Faculty of Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV, Amsterdam, the Netherlands
  • 5NERC Isotope Geosciences Facilities, British Geological Survey, Keyworth, Nottingham, NG12 5GG, UK and Centre for Environmental Geochemistry, School of Biosciences, Sutton Bonington Campus, University of Nottingham, Loughborough, LE12 5RD, UK
  • 6Institute of Arctic and Alpine Research, University of Colorado Boulder, Boulder, CO 80303, USA
  • 7Lamont-Doherty Earth Observatory, Columbia University, 61 Route 9W, Palisades, NY 10964-1000 USA
  • anow at: School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK

Abstract. The West Antarctic Peninsula (WAP) exhibits strong spatial and temporal oceanographic variability, resulting in highly heterogeneous biological productivity. Calcifying organisms that live in the waters off the WAP respond to temporal and spatial variations in ocean temperature and chemistry. These marine calcifiers are potentially threatened by regional climate change with waters already naturally close to carbonate undersaturation. Future projections of carbonate production in the Southern Ocean are challenging due to the lack of historical data collection and complex, decadal climate variability. Here we present a six-year long record of the shell fluxes, morphology, and stable isotope variability of the polar planktic foraminifera Neogloboquadrina pachyderma (sensu stricto) from near Palmer Station, Antarctica. This species is fundamental to Southern Ocean planktic carbonate production as it is one of the very few planktic foraminifer species adapted to the marine polar environments. We use these new data to obtain insights into its ecology and to derive a robust assessment of the response of this polar species to environmental change. Morphology and stable isotope composition reveal the presence of different growth stages within this tightly defined species. Inter- and intra-annual variability of foraminiferal flux and size is evident and driven by a combination of environmental forcing parameters, most importantly food availability, temperature, and sea-ice duration and extent. Foraminiferal growth occurs throughout the austral year and is influenced by environmental change, a large portion of which is driven by the Southern Annular Mode and El Niño Southern Oscillation. A distinct seasonal production is observed, with highest shell fluxes during the warmest and most productive months of the year. The sensitivity of calcifying foraminifera to environmental variability in this region, from weeks to decades, has implications both for their response to future climatic change, and for their use as palaeoclimate indicators. A longer ice-free season could increase carbonate production in this region at least while carbonate saturation is still high enough to allow for thick tests to grow.

Anna Mikis et al.
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Anna Mikis et al.
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Short summary
Antarctic marine calcifying organisms are threatened by regional climate change and ocean acidification. Future projections of regional carbonate production are challenging due to the lack of historical data combined with complex climate variability. We present a six-year record of flux, morphology, and geochemistry of an Antarctic planktonic foraminifera, which shows that their growth is most sensitive to sea-ice dynamics, and is linked with the El Niño Southern Oscillation.
Antarctic marine calcifying organisms are threatened by regional climate change and ocean...
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