Cruise report from M/V Aura week 15-16, 2018

Type: Report
Author: Anna-Kerstin Thell


The spring bloom was ongoing in almost the whole area and large peaks in fluorescence was measured with the CTD.

The deep water in large parts of the Baltic Proper has oxygen concentrations near zero. Completely oxygen free areas, when toxic hydrogen sulphide is formed, were measured in the Bornholm Basin and Western Gotland Basin from 85 meters depth. In the Eastern Gotland Basin was hydrogen sulphide measured from depth exceeding 125 meters. Acute hypoxia (oxygen < 2ml/l) was found in the whole area from 60-80 meters depth, except in the Arkona Basin were the whole water column was well oxygenated.

The surface concentrations of dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) was normal for the season in the whole area. The silicate concentrations in the surface were higher than normal in the Bornholm Basin, Eastern and Western Gotland Basin, the other parts showed values normal for the season.