Growth, Reproduction and Spore Output in Gracilaria Foliifera (Forsskal) Boergesen and Gracilariopsis Sjoestedtii (Kylin) Dawson Around Mandapam

Observations made for one year on the seasonal changes in growth, reproduction and spore output of Gracilaria foliifem and Gracilariopsis sjoestedtii are given. These red algae occurred only a few months during the year in the area of study. Maximum growth of G. foliifera was during April and of G. sjoestedtii was during September and January-March. Tetrasporophytes were more abundant than carposporophytes in G. foliifera, whereas in G. sjoestedtii carposporophytes occurred more. Maximum outputs of tetraspores and carpospores were recorded on the tirst day, and the period of peak shedding of spores coincided with the peak growth period of these seaweeds. There was, however, no definite rhythm of diurnal spore output.