Agence France-Presse: Marine biologists have in recent years rung alarm bells over the invasion in the Baltic Sea of what they believed was a devastating jellyfish, but experts said Thursday they were wrong about the species. “It has previously been feared that the invasive jellyfish that disrupted marine ecosystems in the Black Sea had arrived in the Baltic Sea,” Stockholm University said in a statement. But researchers at the university studying the spread of the American pseudo-jellyfish “have …