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Sinilevätilannekartta esittää pistemäisinä havaintoina sinilevätilanteen noin 400 havaintopaikalta, joista pääosa on yleisillä uimarannoilla. Tilanne arvioidaan havaintopaikoilla kerran viikossa. Myös kansalaiset voivat ilmoittaa sinilevähavaintoja ja perustaa omia havaintopaikkoja havaintolähetin kautta. Huomaa, että havaintopaikan sinilevätilanne voi muuttua nopeasti esimerkiksi säätilanteen mukaan. Sinilevät voivat tuottaa erilaisia levämyrkkyjä. Sinileväpitoisessa vedessä ei pidä uida eikä päästää siihen myöskään kotieläimiä.

Blue-green algae situation 7.6.2024

Blue-green algae notifications start in Midsummer week

Occurrences of blue-green algae in Finnish lakes and the Baltic Sea are monitored also this summer. Risk assessment of the occurrence of blue-green algae in the open sea will be published on Monday 10 June. The weekly blue-green algae reports will be published on Thursdays, starting from the Midsummer week. A summary of the blue-green algae situation in the summer will be published at the end of August.

What everyone should know about blue-green algae

Blue-green algae are at their most prolific around midsummer and in late summer. Large masses of blue-green algae in the water are a sign of eutrophication. Blue-green algae blooms hamper recreational use of waters and may produce algal toxins. You need to watch out for blue-green algae, which is why learning to recognise them is a good idea.

Recognising blue-green algae

Blue-green algae are usually only seen in the water as small, greenish specks. You cannot lift them out of the water with the stick as you can with filamentous green algae. A thick gunk of blue-green algae may build up in surface or shoreline waters. A good way of identifying them is letting some water stand in a drinking glass; if the specks rise to the surface within an hour, they are blue-green algae. The timing helps to tell blue-green algae apart from pollen: pollen is found in early summer, whereas blue-green algae typically occur in the middle and at the end of the summer.

Why should I watch out?

Some blue-green algae are toxic, but it is impossible to tell them from the non-toxic species by visual examination, and consequently you should be careful with all blue-green algae. You should never ingest water containing them, or use it in the sauna. You should also avoid bathing in the water and using it for watering any plants that you intend to eat. Do not allow your dog or other pets to drink water with blue-green algae or play around in it. Algal toxins can also make animals sick or even prove fatal to them.

Where and when?

Blue-green algae occur especially in lakes affected by eutrophication. In the Baltic Sea, blue-green algae blooms are commonly seen in the Gulf of Finland and the Archipelago Sea. When the water warms up around midsummer, the algae start proliferating. Large algae masses can appear quickly in July and August, and in calm weather they rise to the surface as algal blooms. Report your blue-green algae observations on map service or Järvi-meriwiki!

Did you know this about blue-green algae?