What is a coral reef? Coral reefs are huge structures made of limestone that is deposited by living things. There are thousands of species that live in coral reefs, but only a fraction actually produces the limestone that builds the reef. Coral reefs support over 25% of all known marine species. They are one pf the most complex ecosystems on the planet, and are home to over 4, 000 different types of fish, 700 species of coral and thousands of other plants and animals. Other types of plants and animals also contribute to the structure of the reef.
Many types of algae, seaweed, sponge, sediment and even molluscs like giant clams and oysters, add to the architecture of a coral reef. When these organisms die, they are then used as foundations for new corals. Where are they found? Coral reefs are found in over 100 countries. Most reefs are found between the tropics of Cancer and Capricorn, in places such as the Pacific Ocean, the Indian Ocean, the Caribbean, the Red Sea and the Arabian Gulf. Corals are also found further away from the equator in places where warm currents flow out of the tropics, like at Florida and southern Japan. On a world wide scale, coral reefs cover about 284, 300 square kilometres.
The best place for coral to grow is in waters with the temperature being between 21 and 29 degrees. They do grow in hotter and colder places, but the growth rate there are very slow. Corals like shallow waters, where there is lots of sunlight filters through to their algae. Its possible to find corals at depths of up to 91 metres, but reef-building corals doesn't grow very well below 18 - 27 metres. Corals don't grow very well near river openings or costal areas with too much, because corals need salt water to survive. There are generally 4 classes of reefs which scientists divide them into...
1. Fringing reefs: grow near the coastline around islands and continents. They are separated from the shore by thin, shallow lagoons. These are the most common types of reefs. 2.
Barrier reefs: these are also parallel to the coastline but are separated by deeper, wider lagoons. At the shallowest part they can reach the waters surface making a 'barrier' to navigation. The Great Barrier Reef is the most famous example. 3. Atolls: are rings of coral that create protected lagoons, and are usually found in the middle of the sea. Atolls usually form when islands surrounded by fringing reefs sink into the sea or the sea levels rises around them.
4. Patch reefs: small, isolated reefs that grow up from the open bottom of the island platform or continental shelf. They are common between fringing reefs and barrier reefs. Their size is varied, and they don't usually reach the surface of the water. Corals provide shelter for nearly one quarter of all known marine species. The reefs are home to over 4000 species of fish, 700 species of coral, and thousands of other forms of plant and animal life.
The problems >>> There are two types of stresses associated with reef systems: natural and human-induced. The effects of these stresses can range from minor to disastrous. Reefs show a surprising adaptation to short-term natural terrible events, such as hurricanes, and usually recover to normal community structure. These natural events can even be considered helpful in regards to natural diversity. Reefs are not well adapted to survive exposure to long-term stress. Some examples include agricultural and industrial runoff, increased sedimentation from land clearing, human sewage and toxic discharges.
Many land-based activities have important implications for reefs. Agricultural activities can introduce herbicides, pesticides, fertilizers and runoff from animal feed lots. Sewage discharges can introduce nitrogen and phosphate compounds along with pathogens and mixtures of toxics. Uncontrolled land clearing can result in erosion, with the resultant increase in sediment loads to surface waters. Roadways, parking lots and buildings consist of impervious surfaces. These surfaces increase runoff rates and carry with those waters mixtures of dissolved substances to surface waters.
The surface waters in any watershed eventually free into coastal or near-coastal waters. These waters can then impact coral communities linked with these discharge points. Thus, activities occurring in distant locations have impacts to reefs which are far away from these activities. Living coral reefs are the foundation of marine life, and this also means that they are essential for human life, but all over the world they are dead or dying because people are destroying them at a vert fast rate.
Already 10% have been lost, and there are predictions that 705 of all corals on the planet will be destroyed in 20 to 40 years unless people stop doing what they are doing now - i. e. , pollution, sewage, erosion, cyanide fishing, bad tourism. The Crown of Thorn Starfish (COTS) is known as a natural and important member of a coral reef. Adult starfish can reach diameters of 40 cm or more and have lots of arms, ranging from 7 to 23. COTS are covered by numerous long sharp poisonous spines and should be handled with the lots of care if removed on reef sites of commercial or scientific importance are they have to.
COTS outbreaks If large numbers of larvae come across good conditions they may settle as a whole and result in the unexpected amount of large numbers of COTS on widespread coral reef areas. These events are called COTS outbreaks. COTS outbreaks are a natural occurrence on reef systems and have been documented on numerous reefs in the Indo-Pacific, including the Maldives, Indonesia, Australia's Great Barrier Reef (GBR), Vanuatu and Fiji. However, increased nutrients levels because of coastal development, direct and indirect effects of tourism, agricultural practices and exploitation of natural predators may assist larval and young COTS to rapidly outgrow this most vulnerable stage of the COTS life cycle. Once settled into their reef habitat COTS are well hidden and covered with toxic spines. This makes them hard to find and even more difficult to eat.
Man-made influences may be an important factor contributing to the reduced time between outbreak events as currently seen. On the GBR, for example, COTS outbreaks are now recorded every 3-5 years, compared to a cycle of 8-10 years during the 1980's. We need coral reefs, and not just to make the ocean look pretty and colourful, they are more than just that... Food: Millions of species of marine animals, including crabs, eels, molluscs, sponges, worms, grasses, algae, and many more live on reefs and depend on them as nurseries to protect their young. Corals are natural filters of seawater for their neighbours. These reef ecosystems sustain many fisheries that people, mainly costal nations, depend on for their protein intake.
Medicine and other resources: Like in tropical rainforests, coral reefs are a centre of extreme biodiversity, containing a great pool of interesting DNA- most of which hasn't even been understood, or explored yet! Australian scientists have developed a sunscreen from substances that corals use to protect themselves from ultraviolet light. It has a SPF of 50+. Nutrex Corp. has developed an amazing potent pain-killing drug form the poison of reef-dwelling sea snails. There are many more products which have been use from the substances found in coral reefs, and there are surely many more to discover. Fun and Profit: Snorkelers and divers consider coral reefs as big, underwater fun-parks, with colourful delights everywhere- which makes tourist want to spend huge amounts of money, and in many cases greatly helping the economies of the nations...
And what do people do for the coral reefs? Some are killed without noticing, other realise what they are doing but don't care, and others kill them to make money out of tourism, Heres just some of the ways they are being destroyed... Overfishing- Blast fishing Cyanide fishing Sewage Farm runoff Oil and industrial pollution Sedimentation Tourism Disease Climate disruption Coral mining Mangrove destruction The Future >>> Coral reefs constitute one of the most threatened of marine habitats. Because of their slow growth and fairly long life expectancy, they can't easily regenerate themselves, and their difficulty is made harder by the fact that they are permanently lined to the sea floor. That's why increasing pollution and irregular attack by predators prove particularly devastating. A coral colony, which, together with its related flora and fauna, may have developed over 300 or 400 years, can be wiped out in a matter of minutes.
Since coral growth varies from five to 200 centimetres a year, it has been esitmated that some older reefs may have taken from 10, 000 to 30, 000 years to reach their present size. Further hazards, such as pollutants, refuse, sewage, oil, or other toxic substances, released intentionally or through shipwreck, have made the problem worse. Even the methods used in attempting to fix these problems have sometimes made the damage worse. The concern for the safety of coral reefs is getting bigger, but this concern has resulted in worldwide help to develop codes of conduct for maritime vessels. It has also led to the management of research on the effects of man's activities on coral reefs and coastal environments, and to the creation of protected marine areas. These areas, such as the artificial reef created by the EAGLE, can act as replenishment reservoirs for fisheries and are designed to include maximum ecosystem diversity.
Solutions>>> There have been increasing efforts to start better management and conservation processes to protect the variety of these biologically rich areas. Management practices have historically focused on the coral reef proper and not considered associated communities, such as seagrasses, mangroves, and mudflats or defined watersheds (which transport complex mixtures in their waters), in a significant manner. This attempted to manage the reef in isolation, like an island. Current management efforts recognize the importance of including reefs as part of a larger system, where included coastal zone management tools and watershed concepts can be used in the development of full management and protection plans. When reefs are considered as part of a larger watershed, the recognization of the complexity of environmental stresses can be understood. Management plans can be developed to reduce impacts to mangroves, seagrasses and the reef ecosystem, based upon accurate data and a better understanding of the system.
EPA is in the process of developing guidance for a watershed approach to coral ecosystem protection.