Abstract

• Species composition and abundance of phytoplankton were studied bimonthly at Dawei coastal waters in Myanmar during the period from June 2019 to January 2020. Samples were collected at the four stations, namely, Maungmagan (station 1), Kampani (station 2), Nyawpyin (station 3), and Kyaukmatak (station 4). A total of 148 species in which 6 classes are of 36 orders, 48 families, and 65 genera was recorded in the present study. Centric diatoms contributed a maximum percentage composition (80% in total) followed by the pennate diatoms (18%), whereas dinoflagellates comprised a minimum percentage composition, with an average of 2 %. Silicoflagellates were rarely observed. Among the four stations, the highest cell abundance (3139 cells/mL) was observed at station 1, with a 43% in total, which was followed by station 3 (1667 cells/mL) and station 2 (1573 cells/mL), with a percentage of 23% and 22% in total, respectively. The least cell abundance (889 cells/mL) was found in station 4 with a percentage of 12% in total. Phytoplankton abundance was high in the post-monsoon period but the low cell abundance in the monsoon season. Skeletonema costatum, Leptocylindrus danicus, Proboscia alata, Bacteriastrum delicatulum, Chaetoceros compressus, Thalassionema frauenfeldii, Chaetoceros lorenzianus, Thalassionema nitzschioides were dominant species along Dawei coastal waters.