Epiphytic communities on Sargassum piluriferum C. Agardh and artificial seagrasses were examined in Sargassum bed of Ago Bay every month during March 1981 and March 1982. Most of the epiphytes were diatoms, and their cell numbers were 106-107 cells/g dry weight of Sargassum and 103-106 cells/cm of artificial seagrass filament. The diversity of epiphytic flora on the Sargassum was greater than that on the artificial seagrass filament, and occurring species changed more frequently on the Sargassum than on the artificial seagrass filament. Main dominant epiphytes on Sargassum were algae which predominated' particularly in the early stage of epiphytic algal succession on the fresh substrate. The results obtained in the present study suggest that epiphytic flora on, Sargassum remain in the early stage of epiphytic algal succession throughout the year.

We investigated the distribution of settled Sargassum propagules by using artificial sub strata and measured water motion around a Sargassum forest in Gokasyo Bay, Mie Prefecture, Japan. The majority of measured propagules was Sargassum homeri (Turner) C. Agardh and the number of propagules settled on the artificial substrata ranged from 0 to 2197 individuals/ 50cm2. Numbers of propagule settled on the artificial substrata in near shore region were low, while numbers were high around an offshore Sargassum forest.These results indicate that wave motion effected the settlement of propagules to the arti ficial substrata in the following manners.In a near shore Sargassum forest where wave ray concentrates, the propagules that fell onto the substrata were carried out by wave motion. And in a near shore small bay where wave ray disperses and sea bottom is muddy, settlement of silt on the substrata inhibited the settlement of propagules. On the other hand, in offshore regions where wave motion has little effect on the settlement of propagules, distribution of propagules reflected the dispersion from offshore mother plants.

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