Cruise report from R/V Argos week 17, 2006

Type: Report
Author: Bodil Thorstensson


Surface water temperatures were lower than normal throughout the study area (some degrees lower at W Landskrona). Phosphate values in the surface water of the Kattegat, the Sound and the southern Baltic remain higher than normal. Silicate concentrations in the Bornholm Basin were normal, while values in the Kattegat, the Sound and Arkona remain higher than normal. In the Skagerrak, phosphate and silicate concentrations had decreased to normal. Nitrate concentration was at the limit of detection at all stations with the exception of Släggö (see Skagerrak). In the Baltic Proper, oxygen concentrations below 2 ml/l were found at depths exceeding 70 to 90 metres. Hydrogen sulphide was found in the bottom waters of the Eastern and Western Gotland Basins from 125-145 metres. Chlorophyll fluorescence maxima were observed at 10 metres depth in the Fårö Deep and in the western Gotland Basin, where algal bloom was going on. Nitrate was below the limit of detection in the whole Baltic, so in other areas bloom was over. In the central Skagerrak, a fluorescence maximum occurred at a depth of 20 metres. At Släggö, outflow from land led to an enhanced algal bloom. On return to Anholt E, an algal bloom was observed on the last day of expedition.