Cruise report from M/V Meri week 37, 2017

Type: Report
Author: Anna-Kerstin Thell


Oxygen concentrations close to zero were observed in all deep water areas in the Baltic Proper. Anoxic conditions, when hydrogen sulphide forms, were measured in the Western Gotland Basin from about 70 metres depth, in the Eastern Gotland Basin intermediate at 80 meters and nearest the bottom at BY20 and at BY15 Gotland Depth from 225 meters. It was still oxygenated nearest bottom at 4-CTRY-BP but between 70 and 95 meters acute hypoxia was found (dissolved O2 < 2 ml/l). Areas with acute hypoxia were also found in the Bornholm Basin at 65 meters and in the Eastern and the Western Gotland Basins starting at around 60-70 meters. In the Arkona Basin the entire water column was well oxygenated, except at BY1 were acute hypoxia was found close to the bottom.

The nutrients DIN and DIP were generally depleted in the surface water which is normal at this time of year. In the southwestern Baltic Proper small amounts of phosphate was measured. Surface concentrations of silicate were still above normal in the whole investigated area.

The surface water temperature in the investigated area was normal to colder than normal for the season. The salinity in the surface water was normal except from the Skagerak, BY1 and BY29 where it was higher than normal.