The ability of microalgae to survive in marine environments has received considerable attention. It was found that microalgae can produce some metabolites to protect salt injury and to balance the influence of osmotic stresses of the surroundings. The microalgae, bacteria, and cyanobacteria can tolerate up to 1.7 M of salt concentration in marine medium. The salinity condition may stimulate the production of specific components in microalgae. For instance, Fazeli and his colleagues reported that the highest carotenoid contents (11.72 mg/L) of Dunaliella tertiolecta DCCBC26 occurred when the culture medium contained

0. 5 M NaCl (Fazeli et al., 2006). However, salinity conditions may cause negative effects on the microalgal growth. It was reported that a salinity of 35% (standard seawater) or higher led to a reduction in the growth rate and the efficiency of photosynthesis and dark respiration (Jacob et al., 1991).