Rocky shores are one of the most important habitats of marine environment in coastal areas. They host marine organisms including seaweeds because of existence of strong and stable substrate for their growths.
Intertidal rocky shores are a prominent feature on coastal areas of Qeshm Island located at the northern part of Strait of Hormuz. In order to study biomass of seaweeds on rocky intertidal flats of this island, four stations in the south and one station in the northern part of the island were selected. Sampling was done for two periods, summer and winter. It was done during the low spring tide using a quadrate thrown manually and randomly at three times at upper, middle and lower parts of the flats with three replicates. Altogether 73 species of algae were collected and identified. These include 20 Chlorophyta, 10 Phaeophyta and 43 Rhodophyta. The maximum and minimum algal biomass of all stations was recorded in S4 station (117 g.m-2) and S5 station (24 g.m-2) with significant difference between the two stations (P<0.05). Also, the maximum algal biomass was observed for red algae (126g.m-2).