 Other threats include shipping accidents, oil spills, and tropical cyclones.Skeletal Eroding Band, a disease of bony corals caused by the protozoan "Halofolliculina corallasia", affects 31 coral species.According to a 2012 study by the National Academy of Science, since 1985, the Great Barrier Reef has lost more than half of its corals with two-thirds of the loss occurring from 1998 due to the factors listed before.