A diatom bloom was present at the Skagerrak and Kattegat stations with a dominance of Pseudo-nitzschia spp.* and Pseudosolenia calcar-avis. Chlorophyllfluorescence maxima at Släggö, Anholt E and W Landskrona were mainly caused by the same diatom species. There were quite high cell numbers of coccolithophorids, the most abundant in the Kattegat area.
The phytoplankton diversity was low in the Baltic Sea and consequently the chlorophyll concentrations were low. The concentrations were however below what is normal for this month at many stations.