Cruise report from R/V Aranda week 41, 2016

Type: Report
Author: Martin Hansson


The temperature in the surface water was now normal and the cooling of the surface water had started. This was clearly seen in the Skagerrak and Kattegat. The salinity showed normal values in the whole investigated area. Generally, the nutrient concentrations in the surface water had increased since the last cruise in September, which is normal for the season. Though, high concentrations of inorganic nitrogen and phosphate were found in certain parts of the Baltic Proper. The silicate concentration in the whole Baltic Proper continued to be highly elevated. Acute hypoxia (O2 < 2 ml/l) was found at some stations in the Kattegat and the Sound already from 20 meters depth. In the Baltic Proper and the Gulf of Finland acute hypoxia was found from depth exceeding 60-70 meters depth. Anoxia (O2 = 0 ml/l) was found in the Western and Northern Gotland basin and outer Gulf of Finland from depth over 80-90 meters, in the Eastern Gotland basin at intermediate depth and at the bottom. Due to a longer period with strong northerly/easterly winds and high air pressure over the Baltic, the water level is now low in the whole Baltic Sea. This provides favourable conditions for a new large inflow to the Baltic Sea, which is needed to improve the oxygen situation in the Baltic Proper.

Next regular cruise is scheduled to start 14th of November.