Summary
The bottom water oxygen concentrations in Kattegat Proper were not alarming low. In the Belt Sea concentrations below 2 ml/l were recorded at two stations, Fehmarn Belt and Mecklenburger Bucht. No surface accumulations of cyanobacteria were observed. Due to the ongoing inflow oxygen concentrations below 2 ml/l were measured already at depth of 15 metres at station Falster E, closest to the Belt, in the Arkona Basin. In the remainder of this Basin oxygen concentrations were about 2 ml/l at depths exceeding 45 metres. In the rest of the Baltic Proper, station BCS III-10 excepted, oxygen concentrations were below 2 ml/l at depths exceeding 60 to 70 metres. Hydrogen sulphide was found at BY15 (Gotland deep) below 235 metres, in the western Gotland Basin at depths exceeding 70 to 90 metres, and in the Bornholm Basin at the bottom at the stations BY4 and BY5.