Dynamics of harmful microalgae in the Bizerte lagoon

During this study, eight strains of diatoms belonging to the genus Pseudo-nitzschia were isolated from the natural environment at study stations at different times between 2008 and 2009. These strains were examined in detail for their cytology and the ultrastructure of their frustules using an electron microscope (scanning and transmission). In addition, their genomes were sequenced at the LSU and SSU levels using molecular biology methods. Morphometric descriptions and phylogenetic analyses of the eight strains revealed that they did not belong to the genus Pseudo-nitzschia but rather to the genus Nitzschia. Furthermore, the morphological and molecular characteristics identified in the eight strains were not identical to those of any Nitzschia species already described in the literature or to those of Nitzschia recorded in Genbank. Consequently, it was declared a new species and named Nitzschia bizertensis sp. nov. Bouchouicha, Lundholm, Sakka-Hlaili, Hadj-Mabrouk.