Cruise report from R/V Svea week 1-2, 2021

Type: Report
Author: Anna-Kerstin Thell


Surface temperatures in January were above normal in the Baltic Proper and varied from 3.4 in the Kattegat to 6.8 in the Baltic Proper. In the Sound, the Kattegat and the Skagerrak the pycnocline was located from 5-25 m, whereas the surface water was well mixed down to 40-70 m in the Baltic Sea.

The concentrations of phosphate and silicate were normal to above normal for the whole investigated area. Dissolved inorganic nitrogen (DIN) was normal or below normal on the Swedish west coast and above normal in the Baltic Proper.

Oxygen levels in the Arkona- and Bornholm basins were normal or above normal for this time of the year. In the Eastern, Northern and Western Gotland Basin severe hypoxic conditions were observed (oxygen concentration <2 mL/L) below 65 – 90 m. At station BY15 low oxygen concentrations, around 0.1 mL/L was present from 95 – 110 m. At 90 m and from 125 m and below there were completely anoxic conditions and hydrogen sulphide were detected. Hydrogen sulphide were also present from 80 to 125 m in the Eastern, Northern and Western Gotland Basins.