The amount of phytoplankton in the Skagerrak is relatively small and no blooms or accumulations were observed. A large bloom of the dinoflagellate Ceratium furca was found in the Kattegat. Considerable accumulations of blue-green algae, with a dominance of Aphanizomenon sp. and to a smaller degree the potentially toxic Nodularia spumigena, are present in the Baltic Sea. The distribution is however, very scattered. Most algal accumulations north and west of Gotland.