Marine picophytoplankton, in particular cyanobacteria and prochlorophytes are ubiquitously distributed in the worlds oceans and are often especially in the more oligotrophic regions among the most important primary producers. The present work shows the results of in-situ measurements taken on three meridional transects across the Atlantic Ocean. Data for phytoplankton pigment composition and particulate absorption give information about the functional groups found in the study area. Flow cytometry and an analysis of phycobilins were employed to encompass genera of cyanobacteria such as Synechococcus and Trichodesmium. The aim is to improve 1) estimates of global marine primary production and 2) determinations of the distribution of major phytoplankton functional groups, by using hyper-spectral remote sensing data in combination with those in-situ measurements. http://oceanopticsconference.org/abstracts/all