Pinnacle Reefs

The tops of the pinnacle reefs are commonly horizontal and marked by coral knobs and valleys. The prominences are capped by colonies of Diploria labyrinthiformis and Porites astreoides. Isophyllia and Isophyllastrea are abundant. Siderastrea and Stephenocoenia are also recorded. The sides of the reefs are vertical or may overhang. The flanks are characterized by species of Oculina and Madracis. An Isophyllia zone can be distinguished at the top of these bodies, a Madracis zone on the upper slopes, and an Oculina zone in the lower slopes, divided into an upper O. diffusa subzone and a lower O. varicosa subzone.

On many of the reefs, green and red algae are abundant. Halimeda, Penicillus, and Udotea form gardens over much of the surface not occupied by coral. The red algae Galaxaura, Amphiroa and coralline algae are also abundant. On some dead coral heads, the brilliant orange colour and cavernous surface shows the presence of the boring sponge Cliona.