Several spring bloom diatom species were present in the phytoplankton samples from the Skagerrak-Kattegat area, reminding us of the past bloom. The diatom Rhizosolenia hebetata was common at most stations and Skeletonema marinoi was common at one of the Anholt E visits. Cell counts were mostly low. The number of dinoflagellate species were almost the same as the number of diatom species, and many of them heterotrophic. Several heterotrophic small flagellates and ciliates were observed.
In the Baltic, the diatom spring bloom was found mainly in the southern parts and in the Kalmar sound. Diatoms were found at all of the Baltic stations, but in the northern parts of the Baltic Proper, nutrients were high and the cell counts were low. Generally speaking, colonies of small cyanobacteria were abundant and the filamentous cyanobacteria Nodularia spumigena och Aphanizomenon flos-aque were found in very low amounts.