Cruise report from R/V Svea week 28, 2022

Type: Report
Author: Anna-Kerstin Thell


The Skagerrak, the Kattegat, The Sounds and the Baltic Proper was visited during this cruise, which is part of the National Marine Monitoring Programme of Sweden.

Surface temperatures in July were normal for the season at almost all visited stations, except for The Bight of Hanö and Ref M1V1 where temperature was below normal. Satellite observations in the area showed upwelling earlier this week.

Dissolved inorganic nitrogen (DIN) levels were low and showed values below reporting limit in the whole investigated area, considered normal for the season. The concentrations of phosphate and silicate was normal or below normal on the Swedish west coast and slightly above normal in the Baltic Proper.

The oxygen situation in the bottom water showed levels lower or much lower than normal for this time of the year in the Baltic Proper. In the Arkona Basin, hypoxic conditions (oxygen concentration <2 ml/l) occurred in the bottom water. In the Bornholm Basin and The Bight of Hanö  hypoxic conditions was observed below 70 m depth, and hydrogen sulphide was measured in the bottom water from 80 m depth. In the Eastern and the Western Gotland Basins hypoxic conditions occurred from 60-80 m depth. Hydrogen sulphide were present from 90 m depth in the Eastern Gotland Basin and from 70 m in the Western Gotland Basin.