Do toxic cyanobacteria blooms pose a threat to the Baltic ecosystem?

Cyanobacteria, otherwise known as blue-green algae, are oxygenic, photosynthetic prokaryotes.They occur naturally in many fresh, marine and brackish waters worldwide and play an important role in global carbon and nitrogen cycles.In their long history, cyanobacteria have developed structures and mechanisms that enable them to survive and proliferate under different environmental conditions.In the Baltic Sea, the mass development of cyanobacteria is compounded by a high level of eutrophication.The dominant species in the Baltic, the filamentous Aphanizomenon flos-aquae and Nodularia spumigena, can fix dissolved atmospheric N 2 , as a result of which they can outcompete other phytoplankton organisms.Heterocystous, filamentous cyanobacteria also make a significant contribution * This work was supported by the Ministry of Science and Higher Education in Poland (project number 2651/P01/2008/34).