Cruise report from R/V Argos week 23, 1997

Type: Report
Author: Mikael Krysell, Lars Edler


Skagerrak: The surface temperatures varied between 10-14 oC. The nutrient concentrations above the halocline showed low but, for the season, normal values. A strong bloom of Emiliania Huxleyi was observed in the area. Kattegat and the Sound: The surface temperatures varied between 12-13 oC in the very surface. The nutrients concentrations showed, for the season, normal values, even though the silicate concentrations were on the high side of the expected range. All bottom waters were well oxygenated. The plankton flora was relatively poor and dominated by dinoflagellates. The Baltic Proper: The surface temperature was 8-10 oC in the south, east and north, slightly higher in the west. All nutrients showed for the season normal concentrations. The oxygen conditions in the bottom water are displayed in a figure. In the Bornholm Basin at BY4 and BY5 bottom oxygen concentration was about 1 ml/l, a decrease since the last measurements in april. Hydrogen sulphide was found in the Gotland Deep from 200 metres and downwards (low concentrations) and below 100 metres at the stations sampled east-southeast of Gotland as part of the DIAMIX-project. The cyanobacteria Aphanizomenon ”baltica” was found in most parts of the Baltic proper. East of Gotland a strong bloom was visibly observed, dominated by the same cyanobacteria. In the north more than 10 million cells per litre of a yet unidentified spherical, 8 mm in diameter, organism was observed in a subsurface maximum otherwise dominated by dinoflagellates.