Sammanfattning
Surface water concentrations of nutrients, as well as fluorescence, were low for the time of the year, and the oxygen saturation was of the order 103-105%. The surface water temperatures, which earlier, after the long winter, have been below normal, were again back to average levels (4-5°C). The results from the Baltic proper showed a slightly different picture. The surface water was colder (1.3 to 2.5oC) and the nutrient concentrations higher. At some Baltic stations relatively high fluorescence was recorded in the surface water, indicating that the spring bloom was still going on. The oxygen saturation in the Baltic surface water varied between 110 to 115%. At one station only, BY15 (Gotland Deep), hydrogen sulphide was detected, though at low concentrations (6 umol/l) in a thin layer just above the bottom (around 230 m).