Abundance of pico- and nanophytoplankton during the Meteor cruise M87/1

In temperate, subpolar and polar marine systems, the classical perception is that diatoms initiate the spring bloom and thereby mark the beginning of the productive season. Contrary to this view, here we document an pre-bloom of pico- and nanophytoplankton prior to the diatom bloom; a period with excess nutrients and deep convection of the water column. During repeated visits to stations in the deep Icelandic and the Norwegian Basins and the shallow Shetland Shelf (26 March to 29 April 2012), we investigated the succession and dynamics of <10 µm phytoplankton. Water samples were collected from CTD rosette 10 L Niskin bottles and fixed in glutaraldehyde (final conc. 5%), flash frozen in liquid Nitrogen and stored at -80°C until analysis.