Cyanobacterial observations still higher than average, warm and calm weather may further increase surface blooms in late summer

Press release 2022-08-18 at 15:06
Cyanobacteria have been observed in inlets around the coast, such as in the Gulf of Finland off Porvoo and Loviisa on 16 August 2022.

The number of cyanobacterial observations has remained stable throughout Finland. As a result of warm weather, lakes are slightly warmer than average, which helps maintain the growth of cyanobacteria. In sea areas, the amounts of cyanobacteria are still higher than the long-term average, but wind has caused the cyanobacteria to mix with water. Calm and warm weather, as well as strong showers, can increase the number of cyanobacterial surface blooms in late summer.

On Thursday, 25 August, a report summarising the summer’s cyanobacterial monitoring results will be published. The report will show how this year compares to previous summers.

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SYKE observes the cyanobacteria occurrence as part of the monitoring of the state of the environment

The national cyanobacterial monitoring is carried out as part of the monitoring of the state of the environment in cooperation with the Centres for Economic Development, Transport and the Environment (ELY Centres), municipal environmental and health authorities and the Finnish Environment Institute (SYKE). Finnish Rotary Clubs are also actively involved in nationwide cyanobacterial monitoring.

Information on the cyanobacterial situation in the open sea areas is mainly obtained from satellite images, but also from the Finnish Border Guard, the marine research vessel Aranda, the optical device located at the Utö Atmospheric and Marine Research Station, as well as cruise and merchant ships (MS Finnmaid and MS Silja Serenade) equipped with Alg@line measuring equipment. The drift forecasts for cyanobacterial rafts in open sea areas are prepared in cooperation with the Finnish Meteorological Institute's Maritime Services.

The cyanobacterial monitoring is based on the monitoring of cyanobacterial deposits in surface water, and the intention is to provide an overview of the cyanobacterial situation in different water bodies. The monitoring includes about 400 permanent observation sites across the country on inland and coastal waters and in the archipelago.

SYKE reports on the national cyanobacterial situation on a weekly basis every Thursday from the beginning of June until the end of August. The weekly algal reporting on the national cyanobacterial monitoring was launched in 1998.

Several compounds produced by cyanobacteria can cause health hazards

According to the Finnish Institute for Health and Welfare (THL), cyanobacterial occurrences can cause health hazards. Cyanobacteria produce a number of different compounds that can cause symptoms. Some cyanobacteria can produce liver or nerve toxins, but most of the symptoms experienced by swimmers may also be due to other compounds.

Small children and pets should particularly be kept out of water rich with cyanobacteria. Water with cyanobacteria should not be used in a sauna or as washing or irrigation water. If you suspect a poisoning, seek medical advice or take the pet to a veterinarian. If necessary, the Poison Information Centre will provide additional instructions.

The municipal health authorities monitor the cyanobacterial situation on beaches.

Report your cyanobacterial observations to the Järvi-meriwiki (Lake and sea wiki)

In Järvi-meriwiki, maintained by the Finnish Environment Institute, you can establish your own observation site and share cyanobacterial observations or make individual observations when moving around waterways. You can also report observations via the smartphone-friendly Havaintolähetti website. The reported observations are shown on the national cyanobacterial observation map, and they support the national algal situation assessment. Observations about the absence of cyanobacteria are also important.

Järvi-meriwiki is an online service produced in collaboration with authorities and citizens. The service provides basic information on all lakes larger than one hectare as well as different areas of the Baltic Sea. Users can share, for example, photos and other observations on the service.

Municipalities and cities monitor the cyanobacterial situation on the beaches, so it is advisable to report rich cyanobacterial occurrences on beaches to the health authorities of the municipality in question.

Cyanobacterial observations also in the Itä and services

The cyanobacterial maps presented on the websites and combine the observations reported to the Järvi-meriwiki and from the beaches of the City of Helsinki, as well as the observations based on satellite interpretations made by SYKE during the last three days.

This is how you identify cyanobacteria

A small amount of cyanobacteria in the water appears as green or yellowish particles. Narrow stripes of algae can drift to a beach. In calm weather, a substantial amount of cyanobacteria forms greenish or yellowish algal rafts and piles up in coastal water. In spring, yellowish pollen from coniferous trees may also be present in the water. Unlike cyanobacteria, pollen is found not only on the surface water but also, for example, on piers or yard furniture.

Cyanobacteria dissolve into tiny particles in the water if you touch the algal mass with a stick. If the algae become attached to the stick, they are something other than cyanobacteria. In a water vessel, cyanobacteria rise to the surface as tiny greenish particles within about an hour.

Algae bloom risk analysis

Information about algae situation 

Satellite observations

More information

(Telephone 1 pm to 3 pm)


  • Senior Research Scientist Kristiina Vuorio, Finnish Environment Institute SYKE, tel. 295 251 757,

Sea areas  

Coastal cyanobacterial observations

  • Senior Researcher Sanna Suikkanen, Finnish Environment Institute SYKE, Tel. 0295 251 660, (until 19.8.)
  • Senior Researcher Sirpa Lehtinen, Finnish Environment Institute SYKE, Tel. 0295 251 353, (from 22.8.)

Offshore cyanobacterial observations

  • Researcher Hanna Alasalmi, Finnish Environment Institute SYKE, Tel. 0295 251 064, (until 19.8.)
  • Leading Researcher Jenni Attila, Finnish Environment Institute SYKE, Tel. 0295 251 078, (from 22.8.)

State of the Baltic Sea

  • Senior Research Scientist Henrik Nygård, Finnish Environment Institute SYKE, Tel. 0295 251 469, (until 19.8.)
  • Research Professor Markku Viitasalo, Finnish Environment Institute SYKE, Tel. 0295 251 742, (from 22.8.)


  • Communications Coordinator Saara Sivonen, Finnish Environment Institute SYKE, Tel. 0295 251 082, (until 19.8.)
  • Communications Intern Vilma Ruponen, Finnish Environment Institute SYKE, Tel. 0295 251 039, (from 22.8.)

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