Summary
Remnants of the spring bloom were found in the surface water at both stations in the Skagerrak. The chlorophyll fluorescence maxima indicated that the bloom was sinking down considering they were found at approximately 15 meters. Diatoms dominated in the surface water and Skeletonema marinoi and Detonula confervacea were the most abundant. The spring bloom was present at both stations in the Kattegat. The bloom had however emerged downwards on the second sampling occasion at Anholt E. Skeletonema marinoi and Detonula confervacea were the most abundant species. The integrated (0-20 m) chlorophyll a concentrations were within normal for this month. Quite high concentrations were found at single depths between 10-20 meters at most of the stations in the Skagerrak and Kattegat areas. The diatom spring bloom had started in the Kalmar Sound, but not yet in the Baltic proper where the cell densities were very low and no diatoms were found in the samples. Diatoms were present in the area around Bornholm with low cell numbers. The integrated (0-20m) chlorophyll a concentrations were low in the Baltic Sea and below average at many stations. In the Kalmar Sound, the chlorophyll concentrations were rather high.