Floristic and biogeographical trends of the seaweed assemblages
in subtidial rocky areas were evaluated at 10 sites around Espiritu Santo Island
in the Gulf of California. Seasonal sampling in two consecutive years with intensive
surveys in a 500-m2 area at each site was done. An intensive search was
made of previous records from the literature. We found 85 species in the field
with an additional 69 species from the literature, for a total 116 species. Species
composition was significantly different between sides of the island in the first
year, but very similar in the second. Species composition was not influenced
by the presence of epiphytes. Phenologically, most species were ephemeral or
annual with a low reproductive effort. Biogeographically, tropical elements
dominated, but there was an important contribution from temperate species.
Our results indicate that Espiritu Santo Island is a dynamic system that is
strongly influenced by local oceanographic conditions
