The phenology of three species of Sargassum (Sargassaceae, Phaeophyta) in Hawaii*

This study investigated the phenology of three species of Sargassum, S. oligocystum Montagne, S. obtusifolium J. Agardh and S. polyphyllum J. Agardh, found in Hawaii. Field studies using transects and regularly spaced quadrats indicated the presence of slightly irregular annual maxima of standing crop, mature receptacles and thallus length. These maxima occurred from November to April, a time when seawater temperatures are lowest (22–25°C). Culture studies on the growth of Sargassum embryos indicated a temperature of 24°C to be near the optimum for their development. The timing of these various life history phenomena is interpreted as synchronized for maximum in reproduction and resettlement, and providing optimum conditions for embryo growth.