Shark and Marine Conservation   Deep concerns Longlining Trawling Coral reefs Marine pollution     Okay coral? 10,000 years old, fragile and being distroyed Covering an estimated 110,000 square miles, coral reefs support over 25% of all known marine species including some 4,000 different species of fish and 700 species of coral plus thousands of other plants and animals. Coral Reef More than 100 countries boast coral reefs in the tropical waters of the Pacific and Indian Oceans, the Caribbean, the Red Sea and Arabian Gulf and the warm waters of Florida and southern Japan. Whilst coral is often mistaken for a rock or plant, corals are living organisms composed of tiny, fragile animals called polyps. Hard corals grow in colonies and together form the reef. Obvious examples include brain coral and elknorn coral. Their skeletons are made out of calcium carbonate (or limestone). Soft corals do not have skeletons but instead grow wood-like cores for their structure and fleshy rinds for protection. Classic examples of these soft, bendable corals are sea fingers and sea whips. Some coral reefs began growing 50 million years ago although most established coral reefs are between 5,000 and 10,000 years old. Corals grow at different rates, depending on water temperature, salinity, turbulence and the availability of food. The largest corals are the slowest growing species, adding between 5 and 25 mm per year to their length. Faster growing species such as Staghorn corals can grow much quicker, adding as much as 20cm to their branches per annum. Corals are living organisms Some coral reefs began growing 50 million years ago Reefs combine hard and soft corals 32% of coral reefs maybe lost in the next 30 years However, right now coral reefs are in decline around the world. An estimated 11% of the world's corals have been destroyed and a further 16% severely damaged during the 1998 El Nino event - when the water temperature was raise. Furthermore, scientists predict that an additional 32% of coral reefs maybe lost in the next 30 years if human threats are not reduced. Threats to the coral reefs The biggest threat to coral reefs comes from oil, gas and pesticide contamination and when urban, animal waste and fertilizers are dumped in the ocean or rivers carry these pollutants to reef waters. Combined, these pollutants increase the level of nitrogen in the water and cause an overgrowth of algae that smothers the reef causing it to die by blocking off the sunlight. Construction along coastlines and inshore building, mining, logging and farming by coastal rivers can lead to erosion with sedimentation reaching the oceans and supplying rivers. These particles also cover the corals and deprive it of sunlight. The destruction of mangroves and seagrasses, which traditionally have acted as filters for sediment, has lead to a marked increase in the levels of sediment reaching the coral reefs. Once again the knock-on effects of overfishing and other destructive fishing practices have caused the degradation of the world's coral reefs. Indiscriminate fishing techniques such as trawling have devastated corals that have previously occupied an area twice the size of Europe whilst cyanide fishing and blast fishing is adding to the problem. Chemical contamination is the biggest threat to coral reefs Continuing coastline construction can devastate reefs areas Fishing trawlers carve a path of destruction on deep sea corals Tourism and urban pollution compounds reef distruction To catch fish with cyanide, fishermen dive down to the reef and squirt cyanide into coral crevices to stun the fish and make them easier to catch. This, unsurprisingly, poisons the corals beyond repair. Blast fishing uses explosives to kill fish. The by-product is that large areas of reef are torn apart in the process. Unbelievably in poorer countries corals are also exploited for use as building materials, or turned into cement whilst others remove precious corals for gaudy souvenirs or jewellery. Added pressure on the coral reef's future survival is compounded by the increase in tourism, bringing examples of human littering and carelessness from boat drivers, divers and snorkelers and recreational fishing. Ozone depletion and increased carbon dioxide production both combine to raise the temperature of the oceans. Corals are sensitive to changes in water temperature that can cause mass coral bleaching - a condition that kills corals unless the water conditions return to normal. Why should we care? It is argued that nowhere else in the world supports a greater variety of species than our coral reefs. These high-density locations of biodiversity are associated with more than one million species of plants and animals and nearly a quarter of all known marine species. One million species of plants and animals rely on coral reefs A quarter of all marine species are associated with reefs Medical breakthroughs have resulted from coral research Scuba diving brings wealth to countries Already found among these corals are medical treatments for HIV sufferers (most notably AZT) and medicines for those diagnosed with heart disease, ulcers, leukaemia and skin cancer. In fact more than half of all new cancer drug research relies on the study of marine organisms. Even the world's most advanced forms of bone grafting materials are derived from the skeletons on corals. Commercially, coral reefs provide a huge source of income from holiday makers, snorkelers and scuba divers and have been shown to contribute as much as half of many countries' gross national product. As a final note, these beautiful and fragile coral reefs also provide a vital natural protection for beaches and buildings from coastal erosion. What can we do? See our Campaign section for a guide to eco-friendly diving in tropical waters.