Population of Aphanizomenon from the Gulf of Gdansk (Southern Baltic Sea):: differences in phenotypic and genotypic characteristics

In this study, one of the major bloom-forming cyanobacteria in the Gulf of Gdansk (Southern Baltic Sea), Aphanizomenon Morren ex Bornet et Flahaut has been characterized using a polyphasic approach by comparing phenotypic and molecular characteristics. The phenotypic analysis dealt with cell and filament morphology as well as ultrastructure. The molecular phylogenetic analyses were based on sequences of the 16S rRNA gene and the adjacent intergenic transcribed spacer (ITS). We have found the Aphanizomenon population from the Gulf of Gdansk to be significantly different in ultrastructure, morphology from freshwater A. flos-aquae and according to the traditional approach; it could be assigned to different taxonomic units. However, genetic relationship with regard to sequences of the 16S rRNA gene, showed an high overall sequence identity (97.5-99%) to freshwater isolates. Similarly, ITS sequence identity among populations from the Baltic Sea and different freshwater isolates was as high as 90.3-97.7% suggesting one and the same species.