Abundance and composition of microbial plankton communities using flow cytometry on cruise AMT20 (JC053)

This dataset consists of 676 cellular abundance measurements of different microbial populations collected during the Atlantic Meridional Transect programme cruise 20 (AMT20, JC053) between 14th October and 21st November 2010. The cruise track between UK and Chile passed through both North and South Atlantic gyres. This dataset is a contribution to the AMT time-series of core oceanographic measurements. Daily samples were collected at 10 to 12 depth in the upper 300m of the water column using a standard CTD rosette equipped with 24 x 20L Niskin bottles. Samples were fixed with paraformaldehyde (1% w/v final concentration) and stained with the nucleic acid dye SybrGreen I (Sigma-Aldrich, UK). Abundance of different microbial populations was determined according to light-scattering properties (90° or side light scatter, SSC), relative concentration of SYBR Green I stain per particle (green fluorescence; FL1, 530 ± 30 nm) and chlorophyll content (red fluorescence; FL3, >650 nm) using a FACSort instrument (Becton Dickinson, UK).