The phytoplankton samples from the Skagerrak and Kattegat areas had rather high species diversity and the largest number of species, dominated by diatoms, were observed at Släggö in the Skagerrak. At Släggö there was also high numbers of the naked stage of the flagellate genus Dictyocha, which usually has a cross- or star shaped silica skeleton. In its naked stage Dictyocha spp may be harmful to fish. The chlorophyll concentrations were above normal for this month both when integrated from 0-10m (map) as well as 0-20m (graphs) at W Landskrona in the Sound. In the Baltic Sea, the phytoplankton diversity was low, hence few species in low numbers. The stations BY15 and BY29 had very high numbers of colonies of pico cyanobacteria from different species. The threadlike cyanobacterium Aphanizomenon flosaquae was present at most stations in low numbers. The integrated chlorophyll concentrations were normal for this month at the Baltic stations.