Effect of temperature and salinity on the growth and cell size of the first cultures of Gymnodinium aureolum from the Black Sea

Algal blooms are natural phenomena that may cause human health problems, millions of dollars in losses and ecological disasters worldwide. Anthropogenic pressures like eutrophication may increase the frequency and intensity of these phenomena. The Black Sea is characterized by rapid changes in salinity and temperature in surface waters. In addition, it has suffered increasing environmental pressure from human activities. This work presents the first cultures of Gymnodinium aureolum to be isolated from the Black Sea. Morphological and phylogenetic analyses confirmed our strain as G. aureolum. The effects of temperature and salinity on growth were tested in experiments combining two temperatures and five salinities in 10 experimental treatments. This provides baseline data on the physiological adaption and acclimatization potential of the species to bloom under present and future climatic scenarios in the Black Sea. Gymnodinium aureolum grew exponentially in all experimental treatments, except for cultures at salinity 5. Growth rate increased significantly with increasing temperature reaching the maximum at 20 °C and salinity 15 (0.38 ± 0.02 d−1). This suggests an adaptation to the salinity and temperature of Black Sea waters and, together with previous records of G. aureolum in both water and sediments, supports the idea that this may be a bloom-forming population of G. aureolum.