County Administrative Board of Stockholm, Information Office for the Baltic Proper:
"Report on the activities at the Information Office for the Baltic Proper during 2003"
There were no large-scale algal blooms before July. Then came heat and high pressure, and around the
10th of July the first surface accumulations of cyanobacteria were noted at sea. The areas covered by those
increased and in July and August there was on the whole more or less dense cyanobacterial surface blooms
over the entire Baltic Proper. At the beginning of August strong winds mixed down most of those blooms into
the water column. In the middle of August extensive blooms showed up along the southernmost Swedish coasts
resulting in algae drifting ashore. The large-scale blooms decreased at the end of August. However, a major
bloom showed up around Åland as late as during the second week of September. Also small, local
accumulations occurred, especially at the end of summer and during the autumn, but also as late as in the
beginning of December.
According to SMHI the blooms this year were more extensive than the blooms of 2002 based on their analysis
of the 2003 satellite image interpretations and comparison with the results of 2002 (Figure 1)
The oxygen situation in the bottom waters of the Baltic Proper improved during the year. An inflow
of North Sea water early in the year caused a considerable improvement in the oxygen contents in the southern
and south-eastern deep basins up to and including the Gotland Deep. In the latter, the improvement took
place in May and it was still noticed at the end of November. In the south-eastern parts, which may also be
affected by weaker inflows of North Sea water, the situation was better with oxygen levels above
2 ml/L (2,86 mg/L) for most of the year. Still, the situation deteriorated somewhat also in those
areas during the later part of the year.
The bird death has been observed along the Swedish Baltic coast also this year. The Swedish National Veterinary
Institute took samples and tries to find out what causes the death. They try to find out whether it is caused
among other things by deficiency diseases, virus infections or environmental toxins.
Figure 1: The pictures show the total number of days with surface accumulations at a given point
(image pixel) in the Baltic in 2002 and 2003. A comparison between the years shows that the blooms this year
were more extensive than last year. Source: SMHI.
The complete report is available on the internet at: