Sargassum studies in currimao, Ilocos Norte, northern Philippines I. Seasonal variations in the biomass of Sargassum carpophyllum J. Agardh, Sargassum ilicifolium (Turner) C. Agardh and Sargassum siliquosum J. Agardh (Phaeophyta, Sargassaceae)

Three species of Sargassum (S. carpophyllum, S. ilicifolium and S. siliquos um were collected each month for a period of one year from the inter- and s ubtidal zones of Pangil, Currimao, Ilocos Norte, The Philippines. Average m onthly biomass was species-specific and significantly influenced by the eff ect of fertility states of the seaweed, collecting zone, and collecting mon ths. A higher biomass of reproductive plants was accounted for in all speci es in both zones. Among the three species, S. siliquosum had the highest re productive and vegetative biomass in both zones, followed by S. carpophyllu m and S. ilicifolium. Maximum fertility was observed in October for S. carp ophyllum and in November for S. ilicifolium and S. siliquosum. Minimum and maximum reproductive biomass was recorded in May and December, respectively in all species. Biomass of vegetative or non-fertile plants was highest in September in all species except for S. carpophyllum while minimum biomass was recorded in March for S. carpophyllum and May for S. ilicifolium and S. siliquosum. Reproductive plants had more biomass than vegetative plants. The average monthly wet biomass (g m(-2)) of other Sargassum species was hi gher in the subtidal than in the intertidal zone. The biomass of seaweeds a ssociated with Sargassum did not follow a definite pattern. Although water temperature, pH and salinity values were relatively constant, slight variat ions of temperature were positively correlated (P = 0.05) with subtidal bio mass.