Summary
Despite the great secchi depth, quite high phytoplankton cell numbers and many species were found at the Skagerrak coast. In the open sea area, phytoplankton were more scarce. In the Kattegat the diatom Dactyliosolen fragilissimus and the cyanobacterium Anabaena sp. were abundant. In the Baltic Sea, filamentous cyanobacteria were found at all stations in varying amounts. Subsurface blooms were ongoing in the southern Baltic and from the Hanö Bight, throughout the western Gotland Basin. In the Hanö Bight streaks of surface accumulations were observed. East of Gotland, southwards and in the southeastern Baltic no blooms were seen in the samples, but the cyanobacteria species were present in low amounts. Pico cyanobacteria colonies and the chlorophyte Planctonema lauterbornii were abundant. The dinoflagellate Dinophysis norvegica* was present at all stations and was found with relatively high cell numbers at some stations. To follow the surface accumulations of cyanobacteria in the Baltic Sea by satellite interpretations: http://www.smhi.se/en/Weather/Sweden-weather/the-algae-situation-1.11631