In the present study area total number of 88 species of phytoplankton was recorded in the Adirampattinam mangrove water (Station I) and Adirampattinam coastal water (Station II) at different stations during the study period. The percentage composition of each group of phytoplankton in Mangrove water (Station I) was in the decreasing order Bacillariophyceae 29% > Phyrophyceae 23% > Chlorophyceae 19% > Cyanophyceae 16% > Euglenophyceae 8% > Cryophyceae 5%. The percentage composition of each group of phytoplanktans in coastal water (St. II) in the decreasing order Bacillariophyceae 29% > Phyrophyceae 23%> Chlorophyceae 21% > Cyanophyceae 15% > Euglenophyceae 8% > Cryophyceae 4%. Overall average percentage composition at each group of phytoplanktans in both stations (Station I and Station II) in the decreasing order is Bacillariophyceae 29% > Phyrophyceae 23%> Chlorophyceae 20%> Cyanophyceae 16% > Euglenophyceae 8% > and Cryophyceae 4%. Phytoplankton percentage composition exhibited high values in Coastal water (St.II) and low in mangrove water (St. I), because more intensity of light is prevailed during the seasons.
