The major differences between the Skagerrak and Kattegat areas during the latest cruise were the high cell numbers of the diatoms Pseudosolenia calcar-avis and Pseudo-nitzschia spp. in the Kattegat phytoplankton samples. The species’ were present in the Skagerrak as well but in low cell numbers. The dinoflagellate Akashiwo sanguinea was common at the Skagerrak station Släggö and the flagellate Pseudochattonella farcimen was common at the Kattegat station N14. The flagellate Chrysochromulina polylepis* was found at all of the Baltic phytoplankton stations. At three of them, BY29, BY31 and BY38, the species was found with moderate to high cell numbers.