Summary
The integrated (0-10 m and 0-20 m) chlorophyll a concentrations were low but within normal for this month at all stations in the Kattegat and Skagerrak areas, except for Å15 where chlorophyll concentrations were higher than normal. The chlorophyll fluorescence maxima in these areas were caused by diatoms and dinoflagellates. Species of Dinophysis and Chaetoceros were most abundant in these peaks. The integrated (0-20 m) chlorophyll a concentrations in the Baltic Sea where within normal at most of the stations except for BY32 and BY2 where concentrations were higher than normal as well as at BY4, BY10 and BY15 where concentrations were below normal. At all Baltic stations the community was a mixture of dinoflagellates, smaller flagellates, tiny colony forming cyanobacteria and ciliates. Several filaments of the cyanobacterium Aphanizomenon flos-aquae were also recorded at all stations, especially at REF M1V1. Dolichospermum sp. was observed at BY2, BY29 and REF M1V1. The cyanobacteria summer bloom has thus started in the water column, but summer surface accumulations are depending on weather and wind.