Same Jellyfish Species Famous For Clogging Black Sea Now Endangers Fish In The Baltic - Independent

Finnish marine biologists have identified a dangerous species of invasive jellyfish in the Baltic and raised fears that the creature has the potential to drastically reduce fish stocks in what is already regarded as one of the world's most polluted seas. Evidence collected by scientists aboard the Aranda, a ship operated by the Finnish Institute of Marine Research, revealed that the Mnemiopsis leidyi species of jellyfish which caused huge declines in fish stocks in the Black and Caspian Seas had been sighted in the Baltic's Gulf of Finland.

Dr Markku Viitasalo, one of the institute's senior marine biologists, said yesterday that the crew of the Aranda spotted the species of combed jellyfish, which had never been seen in the Baltic before, while cruising in the eastern part of the Gulf of Finland last week. He said the species almost certainly arrived in the Baltic after leaving the waters off North and South America which are their natural habitat and entering the ballast tanks of container ships plying the Atlantic for Europe.

Dr Viitasalo told Der Spiegel magazine that the species had found its way into the Black and Caspian Seas by the same means and had almost completely wiped out fish stocks in both. The discovery followed other disturbing evidence collected by the Aranda which suggested that decades of effort invested by the countries of northern Europe in cleaning up the Baltic had made minimal impact so far.

The institute said research carried out by the ship's biologists had shown that the sea's already damaging phosphorus levels had actually risen off the coasts of Poland and Russia. "It is very important to monitor whether these efforts have had any effect and the answer is not yet," said Dr Viitasalo. Phosphorus, a by-product of agricultural fertilisers which are allowed to run off into the Baltic, and human waste promote the growth of blue algae. The weed-like substance pollutes the Baltic in summer, covering the sea's surface in acres of bad-smelling, green sludge which cuts the vital oxygen supplies needed by fish and other plant life.

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