The oceanographer warns that a lower salt content on the sea floor could drive marine life away. "It's possible the codfish would cease to spawn," Conley says. Furthermore, toxins from the sediment that has thus far been resting on the sea floor could be introduced into the food chain -- poisons such as DDT, an insecticide that was banned in Germany in 1972.
"That's ridiculous," Stigebrandt says, adding that his group has examined the project's risks closely. Far more remarkable, he says, are the results of the testing in the fjord, where sea worms have settled in because there is now enough oxygen for them to inhabit the area. Certainly his critics could have wished for nothing more, the scientist adds. Unpredictable Sea
At the same time, it is also true that immense water circulation can still occur naturally in the Baltic, which is connected to the North Sea via small straits. When wind conditions are favorable, oxygen-rich water flows in, although this has been happening less frequently in recent decades.
In the 1980s, countries that border the Baltic Sea coast began modernizing sewage systems and restricting excessive fertilization by farmers. The result was that fewer nutrients have been drained into the water, but it is likely the state of the inland sea will only change slowly over the next 50 to 100 years. The intent was to make the waters ecologically sound again by 2021.
Advocates of the artificial oxygenation like Stigebrandt argue that waiting alone won't suffice and urge that action be taken. Similar experiments involving pumps are being conducted in the Gulf of Finland. And in the Stockholm archipelago, another group is testing a chemical in the water that has been used to purify sewage. Nevertheless, none of these projects eliminates the root cause of the glut of nutrients in the water.
As to the question of what the effects the project would have on the ecosystem, both supporters and critics are cautious. The sea is unpredictable, they say.