Coral Reefs of the Persian Gulf

Reefs are structures which are built as a result of accumulation of the skeletons of marine species, particularly coral species secreting calcium carbonate, in the form of coastal heights. On the shores of seas and oceans and under proper conditions, some uneven masses of a biological origin are formed as an assemblage of coral polyps, algae, sponge, and shells of marine invertebrates held together by calcium carbonate. Coral reefs are formed in calm and clear waters, with a salinity of 27-40 ppt, at a temperature of 25-30˚ C, with ample light and oxygen. Geographical distributions of coral reefs are found in shallow tropical waters between 30˚ N and 30˚ S latitude. The optimal temperature for the growth of corals is 24-30˚ C, and the optimal depth is about 10 m. However, the corals of the Persian Gulf can withstand a temperature of about 18˚ C and even lower in winter and a salinity of 48 ppt. Coral bleaching is a disease which results from climatic changes, different types of pollution, and stress from human activities in corals’ natural environment and devastates them. For example, in September 2002, because of the bleaching of corals in the Strait of Hormuz and Oman Sea, a great number of the corals degraded. The human stressors imposed on the corals in the region mainly included industrial activities, excavation and land reclamation, oil leakage, etc. Moreover, fishing activities, particularly those involving the use of industrial nets and industrial chain networks, and drainage of cooling water from desalination machines and power plants function as stressors to the corals and the organisms of the natural sea environment, which results in the bleaching of corals all over the region. The limestone masses consisting of coral reefs are also called reef barriers.