High sea temperatures cause the death of stony corals

Abstract

Abstract Stony corals are composed of limestone structures formed by the deposits of living organisms. These are tiny animals (polyps) that live in a symbiotic relation with algae. The algae produce the food energy needed by the polyps by photosynthesis. The coral is as such a colony. Numerous colonies on shallow waters where sunrays can reach them form a coral reef. Coral reefs can be extensive, such as the Great Barrier Reef, or can form localized reefs as in Qatar. Coral reefs harbor numerous organisms including sponges, crabs, sea urchins, brittle stars and fish, and exist where environmental conditions are optimal for their flourishing, such as Southeast Asia. Malaysia is reputed as one of the best areas, where 350 coral species are known to occur. Sea urchins and some fish are ferocious feeders on coral. Extensive feeding may cause the death and bleaching of stony corals. Climate change, in particular high sea temperature, can destroy the coral reef and excessive rains with fresh water seeping to intertidal coral reefs will also cause coral bleaching. Qatar has less than 20 species of stony coral and these are localized in only a few areas. Coastline development, including construction in the sea, is one major cause of loss of natural reefs. Aggressive fishing whether by harpoons or metal traps that are later left behind, destroy the reef. However, the recent bleaching of corals during the last decade and at present, is attributed to two factors: climate change with a rise in sea temperature (1989, 2002, 2010) and oil spills (from the Second Gulf War). Optimum growth temperature for corals is between 20oC to 23oC. In June 2010, the sea temperature recorded was 37.8oC and due to this coral bleaching was observed in local reefs and as well as the death of some fish living in the reef. Bleaching was recorded in 2010 at Halul Island, Ras Rakan, Khereis, Um Alushran and Sherahou.