The surface waters of the lakes are cool, the waters on the shores of the Baltic Sea are mixed.
Cyanobacterial observations the number has started to decline on the shores of the Baltic Sea and in Finnish lakes, says the Finnish Environment Institute in its press release.
In general, cyanobacteria occur most in August, but now the cyanobacterial situation is calmer than usual both on the Baltic coast and in inland waters.
There are significantly fewer cyanobacteria observations on the Baltic coast compared to the 1998-2020 average at this time.
By the sea there has been almost entirely uplift, where the lower mass of cold water rises to the surface and weakens the blooms. On the coast of the Gulf of Finland, algal deposits appear to be almost completely mixed with the water column, as there are only three cyanobacterial observations.
No cyanobacteria have been observed on the coasts of the Gulf of Bothnia, the Kvarken and the northern Bothnian Sea.
According to the Finnish Meteorological Institute, sea surface temperatures are 16–17 degrees in the Bay of Bothnia, 13–17 degrees in the Bothnian Sea, 18–19 degrees in the Archipelago Sea and 12–16 degrees in the Gulf of Finland. There will be strong winds in the Gulf of Finland and the northern Baltic Sea over the weekend, but elsewhere the weather is forecast to be calm.
In the Finnish high seas, the focus of cyanobacterial blooms has shifted away from Finland.
Blue-green algae situation the lakes are very calm compared to the time. No very abundant cyanobacterial blooms were observed at any of the observation sites.
Lake surface temperatures are one to three degrees colder than the long-term average. The surface water temperature in the southern and central parts of the country is between 17–19 degrees, in the regions of Kainuu and Northern Ostrobothnia between 14–16 degrees and in the Lapland region between 10–14 degrees.
Blue-green algae thrive in warm, sunny and calm weather, in which case the algae may form mass deposits on the surface of the water. Blue-green algae appear in the water as greenish or yellowish tips.
In late summer, brown, yellowish or rusty red rafts may also occur in the lakes due to the mass occurrence of rust sponge spores.
Rust sponge spores are harmless to health. Bathing water rich in spores may cause the swimmer the same eye symptoms as pollen rafts.