Seasonal variation of the biomass and size of Sargassum spp. (Sargassaceae, Phaeophyta) in Concepcion Bay, Baja California Sur, Mexico

The seasonal variation of biomass and average size of Sargassum spp. was evaluated in three sites of Bahia Concepcion, Baja California Sur during May 1991 to March 1992. Sargassum sinicola, S. herporhizum and S. lapazeanum were found, comprising 45, 14 and 10% of the total biomass. The remaining 31% of the biomass was Sargassum not identified due to its development stage. An annual biomass production cycle, was detected: the maximum value was registered at the end of spring, it declined in summer, disappeared in autumn and gradually increasing in winter until next spring. The seasonal variation of the size shows a similar pattern of biomass: the maximum average size was registered at the end of spring: the size was reduced in summer, when the plants were senescent; in autumn the size was not registered because only Sargassum vestiges were found; in winter the size was smaller because only Sargassum seedlings were found, and at the beginnning of spring 1992 the size was increased with juvenile plants. Among the species, the size was different: S. sinicola had an average size of 197.4 cm, S. herporhizum of 170.4 cm and S. lapazeanum of 110.0 cm.