Experts fear bad blue-green algae situation in Gulf of Finland this summer

Record amounts of phosphorous in surface waters likely to promote toxic growth

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Environmental experts fear that the coming summer could see thick growths of toxic blue-green algae in the Gulf of Finland.
      If the summer is warm and sunny, the algae is likely to cover most of the Gulf of Finland in July, the hight of the summer holiday season.
      The indicators of a bad algae summer are quite strong. In the western and central areas of the narrow body of water, exceptionally large amounts of phosphorous and other nutrients have risen from the depths to the surface. In a report published on Friday, the Finnish Environment Institute and the Finnish Institute of Marine Research say that this provides excellent conditions for the growth of blue-green algae, as long as there is enough light and heat.
     
Even if the summer is cool, rainy, and windy, the blue-green algae problem is likely to be bad; in such a scenario, the peak growth of the algae would not come until August.
      "The risk of blooms of blue-green algae is very great in the Gulf of Finland - especially at the mouth of the gulf", says researcher Mika Raateoja of the Finnish Environment Institute.
      Heavy blooms of the toxic algae are also expected in the archipelago. The Gulf of Bothnia, on the other hand, is expected to be fairly free of blue-green algae.
      Raateoja expects the first blooms of blue-green algae to emerge right after Midsummer, and to peak in late July. If the early summer is cool, the blooms will come later, and will not be quite as extensive as they would be if the summer is warm.
     
The increasing growth of blue-green algae is largely attributable to an increase in the internal load of pollutants in the sea. The process involves a kind of self-perpetuating cycle, in which nutrients rise to the surface as a result of oxygen depletion on the bottom. The result is rapid eutrophication.
      Heikki Pitkänen of the Finnish Environment Institute sees the higher phosphorous content specifically as a result of the internal load: "External factors cannot explain the increase. The total emissions of phosphorous from Finland have not changed significantly from the 1990s", he points out.
      Storms last autumn and winter mixed up the layers of the Gulf of Finland, and brought much of the phosphorous to the surface.
     
Not all of the signs are bad, however. Pitkänen says that there has been a reduction of nitrogen-based nutrients in Finnish coastal waters, especially in western parts of the Gulf of Finland, where the eutrophication process has stopped.
      Also, bladder wrack seaweed has been found growing in archipelago areas about one metre deeper than ten years ago.
      Bladder wrack is a positive indicator: areas where it grows provide good habitats for many other plants and animals indigenous to the Baltic Sea.


Previously in HS International Edition:
  Water quality in Gulf of Finland deteriorates alarmingly from last year (11.8.2003)
  Blue-green algae problem less serious than feared (31.7.2003)
  Expedition detects little life at bottom of Gulf of Finland (9.6.2003)

Links:
  Finnish Institute of Marine Research press release: Oxygen shortage in the Gulf of Finland deeps

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