Summary
In Skagerrak and Kattegat, nutrient conditions were normal for the season, with the exception of silicate, that in Kattegat showed elevated concentrations. In the Sound, both phosphate and silicate levels were much higher than normal. In the Baltic Proper concentrations of phosphate and silicate were high, while inorganic nitrogen showed normal values in the whole area. Spring bloom was ongoing in large areas of the Baltic proper, while it in some parts was at its end. Oxygen concentrations below 2 ml/l (hypoxia) were found at depth exceeding 80-90 meters in parts of the Bornholm Basin as well as in the Eastern- and Western Gotland Basins. Hydrogen sulphide was measured in the northern parts of the Eastern and Western Gotland Basins, from 100 to 125 meters depth. The effects of the inflow that occurred in November/December 2011 was still seen in the south-eastern part and could also be seen in the southern part of the Eastern Gotland Basin. Oxygen conditions in the Hanö Bight, Arkona- and Bornholm Basins had worsened since the last measurements in April.