Chapter 11 Ecology of Diadema

Abstract

This chapter discusses the ecology of Diadema . Sea urchins in the genus Diadema are among the dominant grazers and forces of erosion of the substratum in shallow tropical reef environments. They compete with other herbivores and also influence the interactions between algae and coral. They play an important role in the ecology of tropical reefs, and the factors that influence their population dynamics and coexistence with other species are of significance to reef ecology and fisheries management. Six species of Diadema have been recognized: Diadema antillarum ( D. antillarum ), Diadema mexicanum ( D. mexicanum ), Diadema savignyi ( D. savignyi ), Diadema setosum ( D. setosum ), Diadema palmeri ( D. palmeri ), and Diadema paucispinum ( D. paucispinum ). The reproductive cycles of Diadema species can be continuous or restricted and can vary from one geographic location to another, indicating that several factors influence reproduction. While they are considered pests as they dominate benthic primary productivity and exclude other herbivores, they are also important in maintaining and restoring coral populations.