Although seas are important waterways, fishing grounds, and so much more, they also host some of the most diverse ecosystems, including coral reef ecosystems. Coral reefs are underwater ecosystems common in seas and related bodies of water. These reefs are built by coral polyps and can take different forms, including barrier reefs, fringing reefs, atoll, and platform reefs. As the name suggests, coral reefs are formed when the coral skeletons cluster in groups to form colonies.
These coral colonies are held together by calcium carbonate deposits present in the seawater. Most reefs form best in clear, shallow, warm, and agitated waters. Although the first coral reefs appeared over million years ago, most of the existing ones are less than 10, years old.
The area covered by the reefs is almost the size of Cuba or half the size of France. Of the reefs in the Indo-Pacific, The Caribbean and the Atlantic area accounts for about 7. The Hawaiian Island, Madagascar, and the Philippines also have coral reefs. Although Southeast Asia is the largest reef region, most of the reefs are owned by wealthy nations. But, which are the largest reef nations?
Below are mentioned some of the countries with the largest reef area and threats to the coral reefs in these countries.
Indonesia consists of over 17, islands located between the Pacific and the Indian Ocean. The country has a marine area of approximately 2. These seas host several marine ecosystems, including diverse coral reefs. The tropical marine waters form part of the Coral Triangle that contains over reef-building species. These algae live inside the coral polyp's body where they photosynthesize to produce energy for themselves and the polyps. The polyps, in turn, provide a home and carbon dioxide for the algae.
Additionally, the zooxanthellae provide the coral with their lively colors — most coral polyp bodies are clear and colorless without zooxanthellae. Some coral species, such as brain coral, are hermaphrodites , which means they produce eggs and sperm at the same time. Sexual reproduction occurs during a mass coral spawning event that, for some species, happens only once a year. Other species, such as elkhorn coral, are gonochoric, which means they create colonies composed of either all males or all females.
Within each coral colony all the polyps will produce only eggs or only sperm. For successful reproduction, the colony must rely on a neighboring colony that produces the other reproductive cell. Most of the substantial coral reefs found today are between 5, and 10, years old, according to CORAL.
They are most often found in warm, clear, shallow water where there's plenty of sunlight to nurture the algae that the coral rely on for food. Coral reefs cover less than 1 percent of the ocean floor — all the reefs combined would equal an area of about , square miles , square km , only about the size of the state of Nevada.
Nonetheless, they are among the most productive and diverse ecosystems on Earth. About 25 percent of all known marine species rely on coral reefs for food, shelter and breeding.
Sometimes referred to as "the rainforests of the sea" for their biodiversity , coral reefs are the primary habitat for more than 4, species of fish, species of coral and thousands of other plants and animals, according to CORAL. Coral reefs are typically divided into four categories, according to CORAL: fringing reefs, barrier reefs, patch reefs and atolls.
Fringing reefs are the most commonly seen reef and grow near coastlines. Barrier reefs differ from fringing reefs in that they are separated from the coastlines by deeper, wider lagoons. Patch reefs typically grow between fringing and barrier reefs on the island platform or continental shelf. The rings of coral that make up atolls create protected lagoons in the middle of the oceans, typically around islands that have sunk back down into the ocean. Coral reefs are also linked ecologically to nearby seagrass, mangrove, and mudflat communities.
One of the reasons that coral reefs are so highly valued is because they serve as a center of activity for marine life. Some soft corals have zooxanthellae to acquire food and energy, but others, such as black corals, exist without this symbiotic relationship. However, the reef-building corals that rely on a symbiotic relationship with algae need shallow, clear water allowing light penetration for photosynthesis.
Stony corals also require tropical or sub-tropical temperatures, which exist in a band 30 degrees north to 30 degrees south of the equator. Coral reefs are among the most biologically diverse and valuable ecosystems on Earth. An estimated 25 percent of all marine life, including over 4, species of fish, are dependent on coral reefs at some point in their life cycle. Approximately half a billion people globally depend on coral reef ecosystems for food, coastal protection, and income from tourism and fisheries.
All of the services provided by coral reefs translate into tremendous economic worth. In the U.
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