A Diversity of Consumers

ECOLOGY The vulnerability of coral reefs to human interference has become only too apparent. Caribbean reefs in particular have been battered by climate change, overfishing, and the excessive growth of seaweed (macroalgae). In order to isolate a key factor that improves reef health even under environmental challenge, Burkepile and Hay corralled herbivorous parrotfish and surgeonfish, alone and in combination, in cages on reefs off the Florida Keys. The outcomes: No fish, and seaweed takes over; add two fish species, and the algae are kept under control and coral cover increases. Alongside ocean surgeonfish, the redband parrotfish were particularly effective consumers of early algal colonizers because the surgeonfish removed the less abundant species of algae that the parrotfish found distasteful. Not all parrotfish were the same: Princess parrotfish preferred the mat-forming seaweeds, and redbands grazed the taller species. These experiments underline the importance of grazer diversity to coral reef health, especially in the Caribbean. — CA Proc. Natl. Acad. Sci. U.S.A. 105 , 16201 (2008).