What happens to the reef when the herbivores (fish, sea urchins) disappear?
Herbivory is a vital component to the ecological balance of coral reefs. Fishes and sea urchins are responsible for limiting the density and spatial organization of plant communities on reefs. Grazing of algae, which is competitively superior to coral, is the primary role of herbivores on reefs. Optimal grazing is a fundamental requirement for coral larvae to settle, mature, and calcify reef structures. Thus, if reef herbivores suffer population declines, slow growing coral will be quickly smothered and overgrown by algae, which would result in substantial coral mortality. A well-documented example of the importance of reef grazing was the almost complete elimination of the long-spined sea urchin, Diadema antillarum, in the Caribbean. Following the population crash of D. antillarum many historically prominent coral reefs in the Caribbean became overgrown and dominated by macroalgae providing a deleterious, yet picture perfect example of the delicate balance of reef ecosystems. -Glynn,
