Low risk for blue-green algae blooms in sea forecast

The risk of widespread blue-green algae blooms in Finnish sea areas is less this summer than the last two years, according to the Finnish Environment Institute (SYKE).

The reason behind the less risk is the algae have less nutrients available in comparison to previous years, said an official press release.

However, significant algae blooms may form in the Gulf of Finland if the summer is warm.

A warm May could cause blooms to occur earlier than normal this year.

According to the SYKE, the risk of blue-green algae blooms in Finnish open sea areas this summer is high in western and central areas of the Gulf of Finland. In addition, the risk is moderate in the northern area of the main basin of the Baltic Sea, the Archipelago Sea and the southern areas of the Bothnian Sea. The risk is low in other parts of the Bothnian Sea and the Bay of Bothnia.

"Weather conditions are a major factor affecting the blue-green algae situation; a warm summer allows more extensive algae blooms.to form. Last year, high nutrient levels in the sea water did not lead to significant blue-green algae blooms because the summer was cold", said leading researcher Harri Kuosa from Finnish Environment Institute.

The peak of blue-green algae blooms in Finnish marine areas occurs usually at the end of July and early August. The blooms may occur locally late into the autumn, but they are not generally as plentiful as during the summer. This year, a warm May might cause visible blooms earlier than normal.

The movement of blooms that have formed in open sea areas to coastal areas depends on the prevailing wind and current conditions. Blue-green algae blooms are particularly likely to move to the archipelago and coastal areas when winds are blowing from the open sea. Strong winds mix the algae bloom with the surface water, which makes it more difficult to detect. When the conditions are calm, blue-green algae resurfaces quickly.

Regional current conditions and nutrition load sources at coastal and island areas may result in local blue-green algae blooms, especially during an extended period of calm and warm conditions. In addition, wind may accumulate algae in coastal waters and on shores.

Blue-green algae may form different types of toxins and agents that irritate the skin. Significant blue-green algae blooms should always be treated with caution.