GROWTH AND REPRODUCTIVE STRATEGIES OF SARGASSUM-MUTICUM (YENDO) FENSHOLT AND CYSTOSEIRA-NODICAULIS (WHIT) ROBERTS

Growth and reproductive strategies of Sargassum muticum and Cystoseira nodicaulis are compared in the lower limit of the intertidal zone. Bo th species have similar life-histories but there is a time segregation in their use of resource as well as differences in their allocation. S. muticum responds directly to changes in conditions and resources: i t grows slowly in winter and very fast in spring. Reproduction occurs in summer and dormancy begins in autumn. C. nodicaulis has a thallus s tructure which allows it to store reserves. it grows in spring and sum mer, reproduces almost throughout the year and begins dormancy at the end of autumn and winter. The reproductive investment is high in both species, but S. muticum produces more germlings per biomass unit. No r elationship has been found between plant size and reproductive investm ent.