Increased risk of exposure to microcystins in the scum of the filamentous cyanobacterium Aphanizomenon flos-aquae accumulated on the western shoreline of the Curonian Lagoon

•Cyanotoxins concentration increases by up to 300-fold in the near-shore waters.•First report on the toxic blooms of Planktothrix agardhii in the Curonian Lagoon.•Removal of cyanobacteria scums in the Curonian Lagoon has to be prioritised.