In tropical coral reefs, plant-eating fish and other herbivores support the dominance of the living coral by eating seaweed. Also known as macro algae, seaweeds create energy from sunlight through photosynthesis, like plants, and support much of the life in the sea. But they also compete with young corals for space, and with the photosynthesizing zooxanthellae that live within and feed the reef-building coral animals for light. In many coral reefs around the world, seaweeds are gaining dominance.
So it is good for the corals to have many different types of fish around to eat their competitors. Algae species have diverse structural and chemical defenses against the fish that graze on them. Parrotfish, unicornfish, and rabbitfish, for example, all eat different species of algae with almost no overlap in dietary tastes, as Douglas Rasher, Andrew Hoey, and Mark Hay observed in no-take marine reserves around Fiji.
Where fishing was forbidden, coral reefs had 2 to 3 times the number of fish species and 3 to 11 times more live coral. The short video from the American Museum of Natural History recaps their paper, “Consumer diversity interacts with prey defenses to drive ecosystem function,” published in the June 2013 issue of Ecology.
Rasher,now a postdoc at the University of Maine’s Darling Marine Center, received ESA’s George Mercer Award for the research, which he conducted as a graduate student at the Georgia Institute of Technology.The Mercer Award recognizes an outstanding and recently-published ecological research paper by a young scientist.