Salinity as a Growth-Regulating Factor of the Toxic Dinoflagellate Alexandrium Minutum

In the last few decades, reports of harmful species have been increasing in the shellfish production areas through the Gulf of Gabès (South-eastern Mediterranean Sea); of particular concern are the outbreaks of the toxic dinoflagellate Alexandrium minutum. Vegetative growth is crucial parameter to understand toxic blooms. In the current study, four A. minutum strains (Am.2, Am.26, Am.1b and Am.3b) were isolated from the Gulf of Gabès and their capacity to adapt to different salinities treatments was investigated. Our results indicated that all studied strains presented a similar behaviour, with the growth rate gradually increasing with increasing salinity between 20 and 40 and decreasing in experiments with salinity higher than 40. The strains were high-euryhaline and showed optimal growth at salinities between 35 and 45, peaking at 40.