Summary
In the Kattegat the spring bloom seemed to be just around the corner. Diatoms dominated and were composed by species commonly found in the spring bloom. The stations in the Skagerrak, on the other hand, had very few cells but still the bloom species, Skeletonema marinoi was present. The integrated chlorophyll concentrations (0–10 m and 0–20 m) were within normal for this month at all stations. Diversity and cell abundance of phytoplankton were very low in the Baltic Sea, with mostly smaller cells such as Cryptomonadales and smaller Gymnodiniales. The centric diatom Actinocyclus octonarius was present at some stations. At BY29 and BY38 some filaments of Aphanizomenon flosaquae were present. The integrated chlorophyll concentrations (0–10 m and 0–20 m) were low but within the normal range for this month at most stations, except at BY2 and BY31 where they were lower than normal. At BY29 the integrated sample (0–10 m) was slightly above normal.