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coral reefs

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Coral reefs are in short terms underwater structure made from calcium carbonate secreted by corals. Coral reefs begin to form when free-swimming coral larvae attach to submerged rocks or other hard surfaces along the edges of islands or continents. This larvae are polyps that produce calcium carbonate, which turns into a hard exoskeleton that provides protection and support for the polyp's body. As a polyp grows it continues to secrete calcium carbonate, this results in that the reef keeps growing. Each polyp links itself together with other polyps to form the reef. Most of a coral reef is actually dead skeletal material. The top layer is usually the only part of the structure that lives. The top layer mostly consists of so called soft corals. The polyps work in symbiosis with the Coralline algae which are also an important part of the reef. The alga deposit limestone in layers over the reef. The limestone strengthens it and protects it from the waves of the sea. As the corals expands and forms reefs they can take three different shapes: Fringing reefs, the most common one, project seaward directly from the shore, forming borders along the shore and around islands. Barrier reefs also border shorelines, but at a greater distance. They are separated from land by a lagoon of open, deep water. If a fringing reef forms around a volcanic island that subsides completely below sea level while the coral continues to grow upward and an atoll has been formed. Atolls are usually circular with a central lagoon as the barrier reefs. Parts of the reef may arise as islands, and gaps in the reef provide access to the central lagoon. Most coral reefs are between 5000 and 10000 years old and they grow very slowly. On average they grow about 2,5 c...

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...umped into the oceans, many off these damadges coral reefs in one or another way. We need to think about that most of the waste we produce will eventually reach the oceans sooner or later. Many of this waste products like agrochemicals, sewage and oil pollution are poisoning reefs. Sewage and runoff from farming, increase the level of nitrogen in seawater, causing an overgrowth of algea which covers the corals so they get cut of from the sun light. Mining, farming, logging and construction causes erosion and this lead to increased sediment in rivers. This will also cover or ’‘smother’’ the corals, the destruction of mangrove forests is exacerbating this problem. Global warming has already led to that increased levels of coral bleching, and this is because corlas cannot survive if the water temperature is too high. Is this the end for an already stressed ecosystem?
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