The toxins produced by blue-green algae blooms have an incredible impact on the whole Baltic Sea.

During the last few weeks, Finland has been basking in record breaking temperatures. In addition to the immediate health risks the recent heat wave has posed for high risk groups, the unusual warmth has brought with it some other unwanted hazards.

Blooms of blue-green algae are a natural phenomenon, but they have recently become more common and intense due to the unnaturally high concentrations of nutrients polluting lakes and the sea. Moreover, the unusually warm weather may trigger a rapid proliferation of the toxic algae.

The bloom period is expected to peak in late July, but according to senior researcher Harri Kankaanpää of the Marine Research Centre of the Finnish Environment Institute (SYKE), the areal coverage and intensity of blue-green algae blooms have increased both in surface and subsurface water in Finnish seas, mainly due to the rise in temperature of the surface water and the availability of phosphates.

It is likely that the continuing warm weather will result in more dense and extensive blooms in the western and eastern parts of the Gulf of Finland. The most substantial surface accumulations of blue-green algae are, however, expected in the south-western sea areas of Finland in particular.

The multiplying number of harmful blue-green algal blooms will increase amounts of toxic substances produced by the algae. “There are always toxic blue-green algae varieties present in the floating algal rafts, and these create the largest single toxin impact on the whole of the Baltic Sea,” Kankaanpää emphasises. Therefore, the occurrence of the blue-green algae during high summer is not only a nuisance on the beaches; its toxins create havoc throughout the ecosystem of the Baltic Sea by accumulating in fish, such as flounder and Baltic herring as well as in blue mussels and other seabed organisms.

JAAKKO TAKKINEN
HT
LEHTIKUVA - PEKKA SAKKI