Summary
Surface water temperatures and nutrient levels were normal in the whole area. Oxygen levels in the bottom water of the Arkona Basin were good. At BY4 (Christiansö) in the Bornholm Basin new water, with an oxygen content of nearly 4 ml/l, had penetrated in close to the bottom. In the intermediate layers in the Gotland Deep, between 80 and 110 metres, there was a layer of water with oxygen concentrations close to 2 ml/l. In the rest of the Baltic Proper, oxygen concentrations below 2 ml/l were found at depths exceeding 60 to 75 metres. Hydrogen sulphide was found at the bottom at BY5 (Bornholm Basin), in the Landsort Deep (BY31) from 100 metres, from 70-90 metres in the Western Gotland Basin and from 90 metres in the northern Eastern Gotland Basin (BY20) and 150 metres in the central Eastern Gotland Basin (BY15). Phytoplankton activity was low in the region.