Insight into Emiliania huxleyicoccospheres by focused ion beam sectioning

[摘要] Coccospheres of a cultured Emiliania huxleyi clone were sampled inthe exponential growth phase and sectioned using a focused ion beammicroscope. An average of 69 sections and the corresponding secondaryelectron micrographs per coccosphere provided detailed information oncoccosphere architecture. The coccospheres feature 2–3 layers on average and20 coccoliths per cell, of which only 15 can be seen in conventional scanningelectron micrographs. The outer coccosphere diameter was positivelycorrelated with the number of coccolith layers. By contrast, the innercoccosphere diameter (around 4.36 μm), and hence the cell diameter,was quasi-constant. Coccoliths were not evenly distributed across thecoccosphere, resulting more often than not in one part of the coccospheredisplaying more coccolith layers than the other. The architectural dataallowed for the calculation of the PIC $/$ POC ratio, the density and thesinking velocity of individual cells. The correlation of these parameters hasimplications for the ongoing debate on the function of coccoliths.

[学科分类] 地球化学与岩石