Photo Elena May 2007, offshore reef, south coast of Vieques.
NOAA's National Marine Fisheries Service announced listing staghorn (Acropora cervicornis) and elkhorn (Acropora palmata) corals as threatened under the Endangered Species Act. This would be the first listing of any coral species as threatened or endangered under the ESA. Once the dominant reef-building corals in Florida and the Caribbean, elkhorn and staghorn corals have almost entirely disappeared. In the past three decades, these corals declined more than 90 percent. Between 1970 and 2000, about 80 percent of Caribbean corals died, and a severe bleaching event in 2005 killed nearly 20 percent of the remaining coral. Bleaching generally occurs when corals reach their thermal limits and expel the symbiotic algae that are vital for their survival.
Global warming is the principal threat to coral reefs. Bleaching events are becoming more frequent and severe as the ocean absorbs heat from the climate system. Warm waters also render corals more vulnerable to disease, and sea-level rise can drown suitable shallow habitat. Additionally, increased frequency and intensity of storms can abrade and damage corals. Carbon dioxide, a greenhouse gas, is absorbed by the ocean and causes seawater to become more acidic. If unabated, ocean acidification is likely to impair coral growth and dissolve coral structures. Other human activities that harm coral habitat include coastal development, boating, fishing, and snorkeling.
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