Cruise report from R/V Aranda week 6-7, 2017

Type: Report
Author: Anna-Kerstin Thell


All nutrients in the surface water were generally normal for the season, except in the Baltic Proper where concentrations of silicate were higher or much higher than normal. The surface water temperature was normal for the season except in the Skagerrak where it was colder. The surface salinity was lower than normal in the Skagerrak and the Kattegat and normal to slightly above normal in the Baltic Proper. In large parts of the deep water in the Baltic Proper the oxygen concentrations were close to 0 ml/l. At the stations in the western Gotland basin hydrogen sulphide was present from 80 to 100 meters, at station BY31 Landsort Deep from 125 meters and at station BY29 no hydrogen sulphide was present this time. Between BY29 and BY15 in the eastern Gotland basin hydrogen sulphide was found at the bottom depth at BY21 and from 215 meters at BY15. Hypoxia, < 2 ml/l was found in all basins from 65-85 meters depths in the Baltic Proper. In the Hanö Bight, hypoxia was found from 70 meters, in contrast oxygen concentrations above 2 ml/l were observed in the bottom water in the Bornholm basin. The fluorescence from the CTD showed an ongoing spring bloom in the surface water in the Skagerrak and the Kattegat.