Cruise report from R/V Aranda week 2-3, 2019

Type: Report
Author: Johan Kronsell


The cruise, which is part of the Swedish national marine monitoring programme visited stations in the Skagerrak, the Kattegat, the Sound and the Baltic Proper. In the Kattegat and the Sound the winter pool of nutrients were mapped.

As usual had large parts of the deep water in the Baltic Proper oxygen concentrations close to 0 ml/l. Anoxic conditions, when hydrogen sulphide can form, were found in the Western Gotland Basin from 80 meters depth, and in the Northern and the Eastern Gotland Basin from 80-90 meters depth. Acute hypoxia, < 2ml/l, was found at 90 meters depth in the Bornholm Basin, and in the Bight of Hanö and south eastern Baltic Proper from 70 meters depth. In the Gotland Basins acute hypoxia was found from about 70 meters depth. In the Arkona Basin the water column was well oxygenated.

Concentrations of nutrients in the form of dissolved inorganic nitrogen, DIN, at the sea surface were on normal or below normal winter levels at all regular monitoring stations. The concentrations of dissolved inorganic phosphorus, DIP, were normal in the Baltic Proper and below normal in the Skagerrak, the Kattegat and the Sound. The silicate concentration was above normal in the northern Baltic Proper, normal in the southern parts, and below normal in the other sea areas monitored.