Archive of Blue-green algae bulletins

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

Published 11.7.2024

Blue-green algae observations have increased slightly throughout the country, and observations have been made even in Lapland. Blue-green algae now occur in the Gulf of Finland and the Archipelago Sea. In the southern part of the Bothnian Sea blue-green algae are just developing. Blue-green algae have still been observed in the coastal area, mainly on the coasts of Uusimaa and Southwest Finland, and the number of observations has not changed much.

The number of blue-green algae observations in inland waters has increased slightly since last week, but the number is at a typical seasonal level. 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 detected at nine observation sites in Southwest Finland, Uusimaa, Pirkanmaa, South Savo, South Karelia and North Ostrobothnia. Some blue-green algae have been observed at 22 inland water observation sites, mainly in Southern, Eastern and Central Finland. The northernmost observation was made in Kemijärvi, Lapland.

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 17 national blue-green algae monitoring sites. Large amounts of blue-green algae were observed in 3 of these sites and some blue-green algae in 13 of them. Blue-green algae are particularly prevalent between Porvoo and Kotka in the inner and outer archipelago and also elsewhere along the coast of the Gulf of Finland. Blue-green algae were also found on the coasts of Southwest Finland and Satakunta. Upwelling has continued in places along the coast of the Gulf of Finland. It has raised colder water to the surface in some parts of the coast, which has contributed to keeping the water clear and limiting the number of blue-green algae.

There are several scattered areas of blue-green algae in the open sea areas of the Gulf of Finland, and the algae have reached the surface, especially in the mouth of the Gulf of Finland. The Archipelago Sea has blue-green algae on the Gullkrona bay and in the archipelago between Rymättylä and Houtskari. Blue-green algae are still developing in the open sea area in the southern part of the Bothnian Sea.

In addition to official monitoring, information on the blue-green algae situation is also gathered from the public. A total of approximately 150 observations made by citizens were obtained through the Lake-seawiki and Vesi.fi this week, which is more than last week.