Improvements seen in sea bottom in Finnish coastal areas

Comb jellies decline significantly

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Recent research voyages by the Aranda of the Finnish Marine Research Institute, and the Muikku of the Finnish Environment Institute have yielded both good and bad news.
      The sea bottom of the outer archipelago of the Gulf of Finland is in better condition than it has been in a very long time. The ice-free winter and windy weather conditions have stirred the water mass so effectively that layers on the bottom have also been replenished with oxygen.
     
“I have sailed with the Muikku for seven years, and this is the first time that I have been able to tell good news”, says Seppo Knuuttila, a limnologist for the Finnish Environment Institute.
      “In 2006, when the situation was so bad that it broke records, more than 80 per cent of the observation points on the coast were oxygen-free. Now the oxygen situation is good in half of 30 observation points”, Knuuttila says.
      A good oxygen situation reduces the amount of phosphorous that is released from the bottom, thereby reducing the internal load in the water. When that happens, life on the bottom increases.
      “The improvement is mainly the result of positive weather conditions. We cannot promise that it will necessarily be permanent.”
     
Knuuttila nevertheless believes that if St. Petersburg manages to continue to cut back on sewage emissions into the Gulf of Finland, and if agriculture succeeds in reducing agricultural runoff, the positive trend could become more permanent.
      Nevertheless, in the depths of the Gulf of Finland, and in the main basin of the Baltic Sea, the oxygen situation is continuing to deteriorate, with toxic hydrogen sulphide appearing in some places.
     
The salt and phosphorous contents of the Gulf of Bothnia and the Bay of Bothnia were found to have been on the increase.
     “We do not know if it is caused by runoff from land, or if there has been a surge of salt water from the main basin of the Baltic”, says special researcher Juha Flinkman.
     Flinkman points out that in Finland and in Sweden, the scattered load caused by individual people in Finland and Sweden, is still a major problem.
     
The comb jellies (Mnemiopsis ledyi) that were found in the Gulf of Finland have decreased considerably. None of the invasive species, which is harmful to native fish stocks, were to be found near the coasts, and in other areas, the ones that were found were small in both size and number.
     Even in the areas where they were more numerous, the comb jellies had declined from their previous numbers.
     Indigenous to the waters off the east coasts of North and South America, the tiny sea creature is believed to have been arrived in the Baltic in ships' ballast waters.


Previously in HS International Edition:
  Baltic Sea panel calls for tighter emission restrictions (19.5.2008)
  New project to treat Poland’s waste water; Finnish foundation helps develop removal of phosphorus (14.5.208)
  Baltic Sea needs urgent attention (14.4.2008)
  Research vessel Aranda to chart distribution of comb jellies in Baltic Sea (5.8.2008)
  Dreaded comb jellies survive winter in Baltic Sea, but do not grow much (16.6.2008)

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