Seaweeds have received much attention in recent years in Toliara. A description is presented here of seaweeds and seagrasses collected on two fringing coral reefs during the hot and cool seasons in 1988 and 1995. Our aim has been to map the habitats of the species collected for different human uses such as exportation, and of the species used by edible animals for feeding. The existence of seaweeds and seagrasses depends on the good health of biotopes which risk being destroyed by sand drift and practice of people walking on the reef.