Figure 1.

(a) Map showing the study area in the North Atlantic Ocean during the Atlantic Meridional Transect 20 cruise in autumn 2010 and the LINK cruise in summer 2011. Symbols indicate the stations at which light/dark sorting experiments were carried out. The boundaries of the oceanic provinces were identified with the Synechococcus distribution (Hartmann et al., 2012) indicated with short dash lines. (b) Latitudinal distribution of the abundance of SAR11 and Prochlorococcus during autumn 2010. Error bars show s.e.