In the Skagerrak diatoms and dinoflagellates were scarce, except for Heterocapsa rotundata. In the Kattegat a diatom bloom of Guinardia flaccida and Proboscia alata decreased between the two samplings. Small amounts of Baltic species indicated outflow of low saline water. Toxic species were not abundant. In the Baltic blue-green algae were abundant around Gotland, but further south present in low abundance. In most parts Chrysochromulina spp. were very abundant.