Coccolithophore distributions of the North and South Atlantic Ocean.

These are data for the fractional abundance of the coccolithophores and detached coccoliths found in the entire coccolithophore and detached coccolith assemblage, observed from Atlantic Meridional Transect cruises 24 and 25. The data were derived from the analysis of scanning electron microscopy (SEM) results. The SEM examination was performed on (mostly) surface and DCM samples following each cruise. Note, there were seven discrete samples from the cruises that did not fall into either the surface or DCM categories but which were taken from interesting features spotted during the CTD profile and these were included in the data set, nonetheless. Samples were prepared for SEM analysis by filtering 100mL seawater onto a 0.4mm pore-size, 25mm diameter, polycarbonate filter, rinsing with potassium tetraborate buffer, then drying the filter at 60degC. The effective filter area of the polycarbonate filter had a diameter of 21mm. Filters were cut and mounted on aluminum SEM stubs (12.7mm diameter) and gold coated prior to analysis on Bigelow’s Zeiss Supra25 field emission SEM, according to Goldstein /et al./(2003). Typically, filters were examined at 15,000X magnification (field diameter =240mm) across the entire stub length of 12.7mm (with a range of 8,000X to 42,000X for imaging, depending on the size of the coccolith or coccolithophore cell). The effective volume of sample thus examined was 0.88 mL. The identification of coccolithophore species was done according to Young /et al./(2003). All taxa with full citations are given at the Nannotax website (http://mikrotax.org/Nannotax3). For AMT 25, in addition to the enumeration of all the coccolithophore species, we also classified three morphotypes of /Emiliania huxleyi/, Types A, B and C (Poulton/et al./, 2011). Diversity (H’), richness (S) and evenness (J’) of the assemblages were calculated (Magurran, 2004) for both the coccolithophore cells as well as the detached coccoliths (for which species origin could be determined).