The genus Dinobryon dominated in the Skagerrak area, the dominance was especially pronounced at the outer station Å17. Low chlorophyll a values clearly indicated that the spring bloom had now ended. Low chlorophyll a concentrations were also recorded in the Kattegat area. Few species were recorded and especially the heterotrophic dinoflagellate Peridiniella danica was common. Only a few cells of the ichtyotoxic (ichtyo = fish) genus Pseudochattonella were recorded on this cruise. A spring bloom situation was evident in the southern and western part of the Baltic Sea. A dominance of spring bloom related diatoms were evident. The northern and eastern parts of the Baltic did not present any indications of a spring bloom.