Summary
At Å17, the most westerly Skagerrak station, the diversity and the total cell concentration were both high and presented a spring bloom situation. At Släggö, at the coast, the phytoplankton diversity and chlorophyll concentrations were a bit lower but still indicated a spring bloom. Diatoms dominated the community at both stations, but high cell numbers of dinoflagellates were also found. The chlorophyll concentrations were within normal for the month and indicated that the spring bloom was ongoing. At station N14 Falkenberg the integrated chlorophyll concentrations (0-10m and 0-20m) were above normal and more so in the upper interval, 0-10m. At Anholt E the highest chlorophyll concentrations were found at 30-50 meters depth which indicated that the spring bloom was at its end and the cells were sinking. The phytoplankton situation in the Baltic was more or less the same as the month before, a few species in low cell numbers. Also the species were the same as the ones observed last month, a few cells of the dinoflagellate Peridiniella catenata and the diatom Chaetoceros castracanei were found at BY2, the threadlike cyanobacterium Aphanizomenon flosaquae was common at BCSIII-10 and BY15 and the green algae Binuclearia lauterbornii was observed at all stations except at BCSIII-10. Colony forming pico cyanobacteria were found in enhanced numbers of cells and species compared to February. The chlorophyll concentrations were normal for this month.