Gulf of Finland has slightly higher oxygen level than last summer

Bottom of eastern part of Gulf largely dead

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The oxygen situation in the Gulf of Finland has improved slightly in all parts of the narrow body of water. Nevertheless, the state of the sea bed remains very poor.
      The oxygen level along the shores and at the open sea is higher than last year, when the the Gulf of Finland was in the worst shape that it had been in eight years.
      However, the oxygen level at the open sea remains low. The open sea in the western part of the Gulf is still without oxygen. Along the coasts, meanwhile, the most extensive oxygen-free zones are in the east. The Archipelago Sea is in the best shape.
      The slight improvement was noted by scientists on the Muikku and Aranda research vessels, which returned from a sample-taking voyage in the Gulf of Finland during the weekend. The results were made public on Monday.
     
"Although the oxygen situation has improved somewhat, we cannot say that there has been a clear leap in a better direction", notes Harri Kankaanpää, a special researcher of the Finnish Marine Research Institute. Kankaanpää headed the voyage of the Aranda.
      There was slightly more life at the bottom, but according to Kankaanpää, the Baltic tellin (Macoma Balthica), a mollusk found on the sea bottom, has declined considerably as a result of the shortage of oxygen.
      Limnologist Seppo Knuuttila, the head scientist on the voyage of the Muikku, estimates that the state of the bottom sediments of the Gulf of Finland is almost as poor as it was in the summer of 2006. The Archipelago Sea is an exception: the sea bottom there is significantly healthier than in the Gulf of Finland, with plentiful and diverse life in most locations.
      In the eastern part of the Gulf of Finland, the bottom was for all practical purposes dead, with virtually no bottom life found at the various locations where samples were taken.
     
"The situation in the east is very poor. The last abundant bottom fauna community was found north of the Porkkala Peninsula (west of Helsinki). Immediately east of that, almost all bottom animals were missing, or only one or two were found at any single location."
      Knuuttila does not see immediate prospects for improvement. Even brief rises in the oxygen level will not help, because animals at the bottom need a constant supply.
      "Masses of dead algae are sinking to the bottom all the time. When this decays, it consumes all of the oxygen. In an oxygen-free environment, phosphorous is released from the sediment on the bottom, which feeds blue-green algae, further encouraging its growth", Knuuttila says, describing the vicious circle plaguing the Gulf of Finland.
     
Large amounts of blue-green algae were found in the central and eastern Gulf of Finland. Especially in the east, the proportion of the toxic algae was clearly higher than in the previous year. In the waters off Helsinki, the algae was fresh and growing, which means that it will continue to bloom if waters stay warm.
     
The best way to improve the state of the Gulf of Finland would be the effective treatment of the sewage of St. Petersburg, Knuuttila says. The efficient removal of phosphorous could significantly reduce the amount of blue-green algae in the Gulf of Finland in just five years.
      "Two fifths of the phosphorous that the algae uses for nutrition comes from St. Petersburg. If waste water were treated in all countries on the Baltic Sea as efficiently as is done in Finland, the phosphorous emissions into the Baltic Sea would be reduced by nearly a third."


Previously in HS International Edition:
  Warm August weather favours growth of algae both at sea and in lakes (9.8.2007)
  Experts fear more toxic blue-green algae than last year (29.5.2007)
  Summer temperature record broken on Tuesday (8.8.2007)
  Blue-green algae affecting some beaches (9.8.2006)

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