海洋酸化
Elkhorn coral are also threatened by ocean acidification. Ocean acidification refers to the growing acidity of marine water caused by the increasing presence of dissolved carbon dioxide, a result of carbon emissions. The skeleton of Elkhorn coral is made of calcium carbonate. Carbon dioxide forms chemical bonds with water and, through chemical reactions, remove carbonate ions that the corals need to make calcium carbonate. With fewer carbonate ions, the coral skeletons are weaker and break easier.