The effect of lowered salinity of sea water on the growth and photosynthetic pigment content in three strains of the microalgae Pseudo-nitzschia pungens (Grunow ex. P.T. Cleve) Hasle, 1993 (Bacillariophyta)

Abstract

The effect of lowered salinity on the growth and the content of photosynthetic pigments (PPs) of chlorophyll a and of carotenoids was studied in three strains of the microalga Pseudo-nitzschia pungens, PP-07, PP-08 and PP-081. It was determined that under a salinity of 24‰ the number of cells and the PP contents from all the P. pungens strains decreased after 1 day exposure compared to the control (salinity 32‰); with increasing exposure, these parameters were restored to the control level. The number of cells and PP content decreased more significantly for a 1 day exposure to salinity lowered to 16‰.The number of dead cells was the highest under salinities of 8 and 4‰ after a 1 day exposure; by the end of the test the number of cells and PP contents were low. It was shown that strains PP-07 and PP-081 were less tolerant to the effects of lowered salinity than strain PP-08.