Archive of Blue-green algae bulletins

Note: This is an archived report.
You can access the latest blue-green algae bulletin here.

Published 4.7.2024

The blue-green algae situation has remained stable since last week. In inland waters, blue-green algae observations have slightly decreased, and the algae situation in coastal areas has remained unchanged. In sea areas, windy weather has largely mixed blue-green algae with the water column. In recent days, blue-green algae have been observed especially in the west of Hanko and the Upinniemenselkä open sea area.

The number of blue-green algae observations has decreased slightly in inland waters since last week. In Southwest Finland, high levels of blue-green algae have been observed at one of the inland water observation sites in national blue-green algae monitoring. Large amounts of blue-green algae have been observed at three observation sites (Pirkanmaa, South Savo and South Karelia). There have been observations of some blue-green algae at a total of 22 inland water observation sites in Southern and Eastern Finland. Unstable and windy weather mixes surface waters, which is likely to slow down the growth of blue-green algae also this week.

There has been little change in the number of blue-green algae observations in the coastal area compared to last week. Blue-green algae have been observed at 19 of the national blue-green algae monitoring sites, with high algae counts at two sites and lower counts at 17 sites. Blue-green algae have been observed mainly on the coasts of Uusimaa and Southwest Finland, and in recent days, blue-green algae have been observed especially in the west of Hanko and the Upinniemenselkä open sea area. The water is currently cloudy in closed and shallow coastal areas, as windy weather has mixed waters and lifted bottom materials to the water column. Both bottom materials and blue-green algae mixed with water can be observed in Tuesday’s satellite images taken in the Upinniemiselkä coastal area.

The windy weather has mixed water in sea areas, so blue-green algae in the open sea areas of the Gulf of Finland are mainly mixed with their water column. In the eastern Gulf of Finland and in the bays, blue-green algae have not yet been detected in the open sea areas of the Bothnian Sea.

In addition to official monitoring, information on the blue-green algae situation has also been gathered from the public. This week, fewer citizen observations were made through the Lake-seawiki and Vesi.fi compared to last week. A total of around 80 observations by members of the public have been received.