Summary
The water temperature in the surface layer had now increased and was substantially normal for the season. In the southern and southeastern Baltic Proper relatively high concentrations of phosphate and silicate were measured. The large inflow that occurred in December 2014 could not be seen further north than at the last expedition and the oxygen levels in the inflowing water had also declined even more. In the northern and western Gotland basin and in the western part of the Gulf of Finland the oxygen situation remains severe as completely oxygen free conditions are found at depths exceeding 70-80 metres. Acute hypoxia was found from 60 metres in the western Gotland basin. In the bottom water in the Bornholm basin and in the Hanö Bight, oxygen levels had declined compared to the previous sampling in July and acute hypoxia was experienced. Oxygen levels in the Arkona basin had increased to >2ml/l and acute hypoxia did no longer prevail.