Tropical cyclones and sea level rise cause major problems including beach erosion and damage to infrastructure in coastal areas. Inexpensive but effective plans for coastal protection will be needed by small island nations and developing countries. Natural breakwater formed by reefs is more cost-effective in coastal protection than the construction of artificial defenses. It provides a habitat for marine organisms and societal benefits including marine products, tourism, and education.

Ocean acidification threatens the survival of coral reef ecosystems worldwide. The negative effects of ocean acidification observed in many laboratory experiments have been seen in studies of naturally low-pH reefs, with little evidence to date for adaptation. Recently, we reported initial data suggesting that low-pH coral communities of the Palau Rock Islands appear healthy despite the extreme conditions in which they live. Here, we build on that observation with a comprehensive statistical analysis of benthic communities across Palau’s natural acidification gradient.