Sea urchin and fish bioerosion on La Reunion and Moorea reefs

Sea urchins and scarid fishes were the most important grazers on the two re efs of La Saline on La Reunion Island (Indian Ocean) and of Tiahura on Moor ea Island (French Polynesia). The total erosive activity of grazers reached a similar maximum value of 8 kg CaCO3 m(-2)yr(-1) on these two high island reefs. The rates of bioerosion by grazers varied considerably among reef h abitats and were linked to the main species of bioeroders. The urchin Echin ometra mathaei was the only important grazer on La Reunion reef flats, when on Moorea Diadema savignyi and Echinothrix spp. played an important role o n bioerosion on the barrier reef flat, and Chlorurus sordidus (scarid fish) and Echinometra mathaei were very active on the fringing reef.