The seasonal variation of Phytoplankton was investigated in Chinnathurai Coast along Southwest coast of India during February 2003 to January 2005. Monthly collections at two stations revealed the existence of 74 phytoplankton taxa belonging to diatoms (58 species) and dinoflagellates (16 species). Dinoflagellates never exceeded 25 percent of the total composition. The diatoms dominated throughout the investigation. Blooms or single taxa dominance was never encountered. Phytoplankton species diversity varied between 4.45 and 7.72; species dominance index between 0.01 and 0.07; species richness index between 4.76 and 9.17 and species evenness index between 1.21 and 1.42. Their density showed considerable seasonal fluctuations with peak abundance during the monsoon and early postmonsoon periods. 

Phytoplakton, seasonal variations, Chinnathurai, India