Articles | Volume 12, issue 3
Biogeosciences, 12, 825–834, 2015
Biogeosciences, 12, 825–834, 2015

Research article 11 Feb 2015

Research article | 11 Feb 2015

Insight into Emiliania huxleyi coccospheres by focused ion beam sectioning

R. Hoffmann1,*, C. Kirchlechner2,5,*, G. Langer3,*, A. S. Wochnik4, E. Griesshaber1, W. W. Schmahl1, and C. Scheu2,4 R. Hoffmann et al.
  • 1Department of Earth and Environmental Sciences, Ludwig Maximilians Universität (LMU), 80333 Munich, Germany
  • 2Max-Planck-Institut für Eisenforschung GmbH, 40237 Düsseldorf, Germany
  • 3Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK
  • 4Department of Chemistry, LMU, 81377 Munich, Germany
  • 5Department Material Physics, Montanuniversität Leoben, Austria
  • *These authors contributed equally to this work.

Abstract. Coccospheres of a cultured Emiliania huxleyi clone were sampled in the exponential growth phase and sectioned using a focused ion beam microscope. An average of 69 sections and the corresponding secondary electron micrographs per coccosphere provided detailed information on coccosphere architecture. The coccospheres feature 2–3 layers on average and 20 coccoliths per cell, of which only 15 can be seen in conventional scanning electron micrographs. The outer coccosphere diameter was positively correlated with the number of coccolith layers. By contrast, the inner coccosphere diameter (around 4.36 μm), and hence the cell diameter, was quasi-constant. Coccoliths were not evenly distributed across the coccosphere, resulting more often than not in one part of the coccosphere displaying more coccolith layers than the other. The architectural data allowed for the calculation of the PIC $/$ POC ratio, the density and the sinking velocity of individual cells. The correlation of these parameters has implications for the ongoing debate on the function of coccoliths.

Final-revised paper