The risk for extensive toxic blue-green algae blooms in many sea areas around Finland is again high this summer, according to the Finnish Environment Institute (Syke).
"This summer, the risk of the formation of rafts of blue-green algae is considerable in the northern part of the main basin of the Baltic Sea, in the Gulf of Finland, the Archipelago Sea and in a large part of the Bothnian Sea," the institute said in press release on Monday.
Risks of blue-green algae (cyanobacteria) blooms in the Bothnian Bay area are low, the institute also noted.
In springtime, as the amount of daylight increases, another kind of algae, phytoplankton, blooms — in amounts "many times higher" than their summertime toxic blue-green algae counterparts.
The spring blooms often turn the water brown and can cause slime to build on fishing nets, for example. However, unlike cyanobacterial growth, phytoplankton blooms don't form algae rafts nor pose dangers to people and animals.
In summer, warmer water speeds up blue-green algae growth, Syke said.
"The formation of large blue-green algae rafts, which can also be seen from satellites, will require favourable growth conditions for a couple of weeks: warm and sunny weather, as well as sufficient phosphorus, and at least a few days of calm wind conditions," the institute explained in the release.
According to the Institute for Health and Welfare (THL), blue-green algae is a potential health hazard, particularly for children and pets. Blue-green algae can form various toxins, including skin or eye irritants, and should be treated with caution, according to Syke.
Starting from the week of Midsummer, Syke plans to publish the results of weekly surveys of the blue-green algae situation in Finland — between 20 June and 8 August. The reports will be issued on Thursdays.
Syke started monitoring the blue-green algae situation at the beginning of this month and will continue the effort until the end of September.
Edited to add map.
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