Visit of a coral reef situated in shallow waters beside the Old Galle Fort.Coral reefs are underwater structures made from calcium carbonate secreted by corals. Corals are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. These polyps secrete hard carbonate exoskeletons which support and protect their bodies. Reefs grow best in warm, shallow, clear, sunny and agitated waters.Often called "rainforests of the sea", coral reefs form some of the most diverse ecosystems on Earth. They occupy less than one tenth of one percent of the world ocean surface, about half the area of France, yet they provide a home for twenty-five percent of all marine species,including fish, molluscs, worms, crustaceans, echinoderms, sponges, tunicates and other cnidarians.Paradoxically, coral reefs flourish even though they are surrounded by ocean waters that provide few nutrients. They are most commonly found at shallow depths in tropical waters, but deep water and cold water corals also exist on smaller scales in other areas.Coral reefs deliver ecosystem services to tourism, fisheries and shoreline protection. The annual global economic value of coral reefs has been estimated at $US375 billion. However, coral reefs are fragile ecosystems, partly because they are very sensitive to water temperature. They are under threat from climate change, ocean acidification ...
http://www.youtube.com/watch?v=MBAeZtxhLus&hl=en
สมัครสมาชิก:
ส่งความคิดเห็น (Atom)
ไม่มีความคิดเห็น:
แสดงความคิดเห็น