Summary
High species diversity was found at all of the four stations in the Skagerrak and Kattegat areas. There were however variations in the total cell counts, and the Kattegat stations had the highest abundancies. The species composition was relatively similar at the various stations, Å17 differed by containing fewer dinoflagellates compared to the other stations. The dinoflagellate Gymnodinium cf. litoralis was found in moderate to high cell numbers at all stations. The potentially harmful group dictyochales* was found with elevated cell numbers in the Kattegat and at Släggö in the Skagerrak. The integrated chlorophyll concentrations were somewhat low in the Skagerrak and somewhat high in the Kattegat for this month. Species diversity and total cell numbers varied across stations in the Baltic Sea, with moderate levels at most sites. The diatom Dactyliosolen fragilissimus was abundant at several locations, particularly dominating at BY5, BY38, and BY39. Smaller cells, such as Cryptomonadales and species from the genus Pyramimonas, were commonly present. Toxin-producing dinoflagellates (Dinophysis acuminata* and Phalacroma rotundatum*) and bloom-forming cyanobacteria (Aphanizomenon flosaquae and Nodularia spumigena*) were detected in some samples. Integrated chlorophyll concentrations were generally normal for the month, with some deviations observed at specific depths.