A sea turtle rests on coral while a diver hovers the background. Coral reefs are formed from calcium carbonate secreted by tiny animals called polyps. These colonies of polyps and the reefs they create are among Earth's most diverse ecosystems, providing shelter for a wide variety of fish, mollusks, sponges, and other sea creatures. They are important for tourism and the fishing industry. Corals are highly sensitive to both warming ocean temperatures and ocean acidification brought about by increased atmospheric carbon dioxide. NCAR scientists are studying the effects of warming and acidification on reefs and the marine populations they support.
