Elkhorn coral

"Elkhorn coral is one of the most important corals in the Caribbean. It, along with staghorn coral and star corals . . . built Caribbean coral reefs over the last 5,000 years. Elkhorn coral can form dense groups called “thickets” in very shallow water. These provide important habitat for other reef animals, especially fish. In the early 1980s, a severe disease event caused major mortality throughout its range and now the population is less than 3 percent of its former abundance. The greatest threat to elkhorn coral is ocean warming, which causes the corals to release the algae that live in their tissue and provide them food, usually causing death. Other threats to elkhorn coral are ocean acidification (decrease in water pH caused by increased carbon dioxide in the atmosphere) that makes it harder for them to build their skeleton, unsustainable fishing practices that deplete the herbivores . . . that keep the reef clean, and land-based sources of pollution that impacts the clear, low nutrient waters in which they thrive."