Archive of Blue-green algae bulletins

Note: This is an archived report.
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Published 17.8.2023

Blue-green algae situation has remained stable both in lakes and at sea

Blue-green algae observations in lakes and coastal areas have increased slightly since last week. However, the situation is normal for the season and, in lakes, even better than usual. In sea areas, blue-green algae close to the surface have been observed mainly in the eastern parts of the Gulf of Finland. Elsewhere in the open sea, blue-green algae are mixed with water.

The blue-green algae situation is normal on the coast and slightly better than usual in lakes. The number of blue-green algae observations has increased slightly since last week, both in lakes and at coastal areas. In addition to the local blooms observed, blue-green algae may be mixed with water, and warm and calm weather may contribute to the development of blue-green algae blooms even now, in late August.

Very abundant blue-green algae have been observed at only two inland observation sites of the national blue-green algae monitoring this week, Lake Rusutjärvi in Tuusula and Lake Sääskjärvi in Iitti. There have been observations of abundant blue-green algae at nine observation sites in different parts of Finland. A small amount of algae has been observed at 27 lake observation sites.

At coastal observation sites, very abundant blue-green algae blooms have been observed at one site, Munkkiniemenranta in Helsinki. Similarly, abundant blue-green algae have been observed at one observation site, while some blue-green algae occur at 20 coastal observation sites. Coastal blue-green algae observations mostly occur on the Gulf of Finland, the Archipelago Sea and the Southern Bothnian Sea.

In addition to the official blue-green algae monitoring observations, citizens have made a total of 34 observations, 14 of which concerned blue-green algae.

During the past week, blue-green algae have been observed close to the surface in open sea areas mainly in the eastern parts of the Gulf of Finland. In other open sea areas, blue-green algae are mixed with the water column.