Archive of Blue-green algae bulletins

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Published 10.8.2023

Strong winds have dispersed blue-green algae surface blooms in inland waters and at sea

The blue-green algae situation in lakes is calm considering the time period. Even in sea areas, blue-green algae have only been detected in subsurface layers in the eastern Gulf of Finland. However, warm and calm weather may further enhance the development of blue-green algae blooms.

Strong winds during the past week have in many places mixed blue-green algae blooms with the water column. The national blue-green algae monitoring’s observations on abundant blue-green algae blooms have decreased since last week, and the number of blue-green algae observations is lower than the long-term average of the time period.

Very abundant blue-green algae blooms have not been observed. Abundant blue-green algae have been observed at five inland water observation sites of the national blue-green algae monitoring. There have been observations of some blue-green algae at 27 inland water observation sites in different parts of Finland. On the coast, abundant blue-green algae have been observed at one observation site in Southwest Finland and some blue-green algae at 14 observation sites along the coasts of the Archipelago Sea, the Gulf of Finland and the Bothnian Sea.

Some blue-green algae have been observed in the subsurface layers early in the week, predominantly in the eastern Gulf of Finland. In other sea areas, strong winds have mixed algae with the entire water layer and no large surface formations have been observed.

Warm and calm weather may further contribute to the development of blue-green algae blooms both in inland waters and in sea areas.