Cruise report from R/V Aranda week 16-17, 2017

Type: Report
Author: Anna-Kerstin Thell


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 90 meters depth and in the Eastern Gotland Basin, but then only in the Gotland Deep BY15 nearest bottom (235 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 65-80 meters. Silicate concentrations were above or more than above normal in the whole area except for the Skagerrak were it was normal. The surface concentration of phosphate and inorganic nitrogen was normal for the season in the investigated area. The surface temperature was normal for the season but the salinity was slightly higher than normal in the Skagerrak, Kattegat and Eastern Gotland Basin. The spring bloom was ongoing in almost the whole area.