Effect of culture density on sexual reproduction of Ardissonea crystallina (Bacillariophyta) inhabiting the Black Sea

One of the key factors that affect the sexual reproduction of diatoms is the cell concentration in the mating experiments. The concentration of pheromones, which probably initiate gametogenesis in the mixture of cells of opposite sexes, depends on the culture density. The influence of the cell concentration and inoculation pattern on the sexual reproduction has been studied in the experiments with the taxonomically important marine diatom Ardissonea crystallina (C. Agardh) Grunow. Several clones have been isolated from samples collected near Sevastopol (Black Sea). The cell concentration that is most favorable for the species reproduction has been estimated. A low initial density may also increase the time required to start heterothallic sexual reproduction. The optimum cell concentration that is most favorable for the species reproduction has been estimated. Larger volume of the medium allowed reproduction at higher cell concentration. If the initial concentration of cells was greater than the optimal density, reproduction often did not occur, probably due to the cell metabolism products accumulated in the culture.