Cruise report from R/V Aranda week 10-11, 2017

Type: Report
Author: Martin Hansson


In large parts of the deep water in the Baltic Proper the oxygen concentrations were close to zero. Completely oxygen free conditions, when hydrogen sulfide is measured, was found in the Western Gotland Basin from 100 meters depth and in the Eastern Gotland Basin but then only in the Gotland Deep BY15 from 225 meters depth. In the remaining areas in the Eastern Gotland Basin oxygen concentrations was close to zero but no hydrogen sulfide were observed at any depth. Acute hypoxia was found in all basins in the Baltic Proper at depths exceeding 60-70 meters. The surface concentration of phosphate was elevated in the Western and Eastern Gotland Basin. While, the phosphate concentration in deep water, from 70 to 100 meters, in the Eastern Gotland Basin was lower than normal. Silicate concentrations were elevated in the whole Baltic Proper. The concentration of inorganic nitrogen in Skagerrak was lower than normal. However, remaining nutrients in both Skagerrak and Kattegat showed normal levels. The surface temperature was normal for the season but the salinity was higher than normal in the Eastern, Northern and Western Gotland Basin. The spring bloom was ongoing in Skagerrak and Kattegat.