Archive of Blue-green algae bulletins

Note: This is an archived report.
You can access the latest blue-green algae bulletin here.

Published 6.7.2023

Cool and rainy weather has kept the blue-green algae situation calm on lakes and at sea

This week, the number of blue-green algae observations in inland waters and on the coast has been below average, as a result of cool weather and rainfall. The abundant surface blooms of blue-green algae observed at the end of the week in Finland’s sea areas, are now mixed with the entire water layer.

Cool weather and rain have led to fewer blue-green algae observations due to the mixing of surface waters. This week, there are clearly fewer blue-green algae both in inland waters and on the coast than is typical of the time. The number of blue-green algae occurrences has also decreased in terms of citizens’ observations.

Abundant algae and some blue-green algae have been detected at 24 observation sites in different parts of Finland. For the coastal observation sites, abundant blue-green algae have been observed at one site and some blue-green algae at five sites. These observations have been made on the southwestern and southern coasts.

In the Gulf of Finland, especially between Hanko and Porvoo, both satellite observations and the Alg@line measurements made by merchant vessels showed abundant blue-green algae in the surface layers of water at the end of the previous week. Some blue-green algae were also observed in the Archipelago Sea, more on the west side than on the east side. However, the windy and rainy weather of the weekend and the beginning of the week have mixed the blue-green algae on the surface into the entire water layer. No surface masses have been observed in open sea areas this week.

 

The information on this page was produced by the Finnish Environment Institute (Syke).