Summary
Nutrient concentrations in the surface waters were normal for the season almost everywhere, with the exception of phosphate, that in the south-eastern Baltic showed clearly enhanced values, and silicate that in the eastern and western Gotland Basins also showed values above normal. A cyanobacteria bloom was observed in several areas in the Baltic Proper. Significant surface accumulations were observed especially in the Arkona Basin and in the western Gotland Basin. On ship microscopy showed that the potentially toxic species Nodularia spumigena was common. Oxygen concentrations below 2 ml/l were found in the whole Baltic Proper at depths exceeding 70 metres. Hydrogen sulphide was found at the Gotland Deep, in the Western Gotland Basin, the Hanö Bight and parts of the Bornholm Basin.