Summary
A minor autumn bloom was observed at the Skagerrak and Kattegat stations with high phytoplankton diversity. The flagellate Dictyocha speculum* was found in a so called naked stage, without the silica structure, when the species is potentially harmful. The species was numerous in the Skagerrak and less so in the Kattegat. At Å17 in the Skagerrak and Anholt E in the Kattegat, the integrated chlorophyll concentrations from 0-10 m were above normal for this month. The cyanobacteria season was finally over in the Baltic Sea. The phytoplankton diversity was low and consequently the chlorophyll concentrations were also low at several stations. At BY15 however, the chlorophyll concentrations were quite high, partly caused by the dinoflagellate Prorocentrum cordatum.