Wind and lack of heat limited Finland’s blue-green algae blooms

Blue-green algae blooms have been unusually limited in Finland this summer, despite conditions being favourable for their formation at the start of the season, Yle reports.

Strong surface blooms have not occurred. Seppo Knuuttila, a specialist researcher at the Finnish Environment Institute, attributes the situation to several factors.

First, the weather has perhaps been windier than average. Blue-green algae thrive when the algae mass rises to the sea surface and is carried by the wind towards the shore. Such conditions did not develop this summer.

Second, efforts to reduce nutrient loading in water bodies are producing results. Knuuttila said the worst may be over and that the number of blooms is unlikely to increase from previous levels.

He cautioned, however, that the condition of water bodies has not improved significantly, even though nutrient loading has decreased. Conditions supporting blooms will remain for decades.

There were also no prolonged heatwaves this summer. Such periods create favourable conditions for blue-green algae blooms.

Climate change could worsen the situation in the future. As the Baltic Sea warms, conditions for blue-green algae blooms will improve. Warmer water contains less oxygen, which can cause increasing amounts of phosphorus, an important nutrient for blue-green algae, to be released from the seabed.

Nutrient loading from land could also increase as winters become warmer and rainfall increases.

“We will have to work harder to protect the waters unless we succeed in stopping global warming,” Knuuttila said in an interview with Yle’s Aamu programme.