King of the seas keeps reefs in order.

This article reports that a model of the food web in a Caribbean reef suggests that sharks are vital for the health of coral reefs. According to the model, created by Enric Sala of the Scripps Institution of Oceanography in San Diego, California, and colleagues, the removal of top predators allows lesser predators such as groupers to thrive, leading to a reduction in the number of algal feeders such as parrotfish. That makes reefs more vulnerable to disturbances that kill corals, such as disease, pollution and global warming. The study suggests that the loss of sharks may have contributed to the decline of reefs in the Caribbean, most of which are now dominated by algae.