2.443 107 cells mL1, respectively. The differences of cell density of Tetraselmis sp. in other salinity were insignificant .At the end of the experiment, the specific growth rate of both Nannochloropsis sp. and Tetraselmis sp. was found to be significantly higherwhen cultured at 30 ppt under control condition (Table 2). In addition to salinity stress, the differences in pHwere also showed to lead to the change in the specific growth rate of bothmicroalgae. In this study, both Nannochloropsis sp. and Tetraselmis sp. cultured at pH 5.5 and 9.5 showed a significantly lower cell density as compared to pH 7.5 and 8.5.