Overfishing blamed for ocean reef loss

SANTA CRUZ, Calif., Jan. 14 (UPI) -- Overfishing of reefs leads to explosions in populations of sea urchins, which destroy coral algae that build tropical reef systems, U.S. researchers say.

An 18-year study of Kenya's coral reefs by the Wildlife Conservation Society and the University of California at Santa Cruz has found in contrast, reef systems closed to fishing have fewer sea urchins because predatory fish keep them under control, with resulting higher coral growth rates and more structure, a WCS release said Friday.

Large numbers of grazing sea urchins reduced the abundance of crustose coralline algae, a species of algae that produce calcium carbonate, the basic building material of ocean reefs, researchers found.

"These under-appreciated coralline algae are known to bind and stabilize reef skeletons and sand as well as enhance the recruitment of small corals by providing a place for their larvae to settle," WCS Senior Conservationist Tim McClanahan says. "This study illustrates the cascading effects of predator loss on a reef system and the importance of maintaining fish populations for coral health."

The study shows improving the management of tropical fisheries can help reefs to grow and persist in a changing climate, researchers say.

"The survival of coral reefs is critical for hundreds of millions of people who depend on these complex systems for coastal protection, food, and tourism revenue around the globe," Caleb McClennen, director of WCS's Marine Program, says.