During the March cruise, Paralia sulcata and Coscinodiscus spp. Were dominant species in the samples. The high contribution of diatoms (80%) coincided with the high Chl a in the coastal water. Whereas the contribution of prasinophytes seemed to increase in the central area with a relatively lower Chl a concentration. The prasinophytes were the second most important group in the central area during March. The relative abundance (28 +- 7%) was significantly higher than those in April and August (p < 0.01).