Identification of toxigenic Cyanobacteria of the genus Microcystis in the Curonian Lagoon (Baltic Sea)

In 2002–2008, seasonal (April–November) monitoring of the phytoplankton in the Russian part of the Curonian Lagoon at five fixed sites was performed. A total of 91 Cyanobacteria, 100 Bacillariophyta, 280 Chlorophyta, 21 Cryptophyta, and 24 Dinophyta species were found. Six potentially toxic species of cyanobacteria: Aphanizomenon flos-aquae , Anabaena sp., Microcystis aeruginosa , M. viridis , M. wesenbergii , and Planktothrix agardhii dominated the phytoplankton biomass and caused water blooms. The seasonal average phytoplankton biomass ranged from 30 to 137 g/m 3 . The cyanobacteria’s biomass varied from 10 to 113 g/m 3 forming 30–82% of the total with a mean of 50%. With the aid of genetic markers (microcystin ( mcy ) and nodularin synthetases), six variants of the microcystin-producing gene mcy E from the genus Microcystis were identified. Due to the intensive and lengthy blooms of potentially toxic and toxigenic cyanobacteria, the environmental conditions in the Curonian Lagoon appear unfavorable. The water should be monitored for cyanotoxins with analytical methods in order to determine if the area is safe for recreational use.