Cruise report from M/V Aura week 50-51, 2017

Type: Report
Author: Martin Hansson


The deep water, in large parts of the Baltic Proper, oxygen concentrations were near zero. Completely oxygen free areas were found in the Western Gotland Basin from 70 meters depth and in the Northern Baltic Proper from 90-125 meters depth. In the Eastern Gotland Basin low concentrations of hydrogen sulphide, which forms when the oxygen concentrations drops below zero, was found close to the bottom. Acute hypoxia (oxygen < 2ml/l) was found in the Bornholm Basin, Eastern Gotland Basin and in the Western Gotland Basin already at 55-70 meters depth, in Hanöbukten and at Ölands S Udde even shallower from 40-55 meters depth.

The whole water column in the Arkona Basin was well oxygenated.

The surface concentrations of dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) was higher than normal in the Eastern, Western and Northern Gotland Basin. Silicate concentrations in the whole Baltic Proper were still much higher than normal and the values had increased further compared with the measurements performed in November. In Skagerrak and Kattegat the nutrients was overall normal for the season.