A diatom bloom was observed at the Skagerrak coast (Släggö) at the time of the latest sampling, 22nd of August. The diatom Skeletonema costatum was found with high cell numbers and the species diversity was high. The chlorophyll a concentration in the surface was enhanced, although the integrated chlorophyll value (0-20 m) was within average at Släggö, as well as at all of the Skagerrak and Kattegat stations. Low chlorophyll values, within average for this time of the year, were found at all of the Baltic stations. The species diversity was low, but relatively large amounts of filamentous cyanobacteria were present at BY15, BY38 and in the Kalmar Sound. Colonies of small cyanobacteria were abundant at all of the Baltic stations.