Sampling was performed during the MSM-21/3 expedition (Cembella et al., 2016) aboard the RV Maria S. Merian at the western coast of Greenland and Iceland between July 27 to August 8, 2012 (Fig. 1). Water samples were collected in the epipelagic zone by Niskin bottles mounted on a rosette-sampler with conductivity, temperature and depth (CTD) sensors to measure temperature and salinity. In total, 15 stations were sampled at the surface layer (over the upper 30 m).