Summary
The diatom spring bloom was ongoing at Anholt E and Fladen in the Kattegat, but at all other Kattegat and Skagerrak stations the total cell numbers were moderate although the scene was set when it comes to species. The abundance and biodiversity were low in the Baltic Sea, although moderate amounts of Skeletonema marinoi were observed at BY2 Arkona. The integrated chlorophyll concentrations (0–10 m and 0–20 m) were within normal for this month at all stations.