The algal assemblage on the reefs of Vaan, Koswari and Kariyachalli islands of Tuticorin group in the Gulf of Mannar was studied for a period of one year. The amount of algae was high during January to April, whereas it was less during May to September. Meanwhile the percentage of rubbles was higher during May to September and lower in January to May, which indicated the coral algal phase shift. The green algae Halimeda spp. was found to be the dominant algal representative. Its average percentage in Vaan, Koswari and Kariyachalli was 11.56*1.09, 11.12*1.70 and 8.7721.72 respectively. The ecological importance of algal assemblage in the coral reef ecosystem is discussed.

Macro algae, assemblage, reefs, Tuticorin, India