Coral Reefs

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* Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny 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. The polyps are like tiny sea anemones, to which they are closely related. * Coral reef ecosystems support a variety of human needs. They are important for subsistence, fisheries, tourism, shoreline protection, and yield compounds that are important in the development of new medicines. * At least 500 million people rely on coral reefs for food, coastal protection, and livelihoods. It is estimated that coral reefs provide $375 billion per year around the world in goods and services. * Silt from eroded soil in runoff water can block sunlight. Without sunlight, photosynthesis does not occur and reefs gradually die. * Overfishing: affects the ecological balance of coral reef communities, warping the food chain and causing effects far beyond the directly overfished population. * Climate change: Corals cannot survive if the water temperature is too high. Global warming has already led to increased levels of coral bleaching, and this is predicted to increase in frequency and severity in the coming decades. Such bleaching events may be the final nail in the coffin for already stressed coral reefs and reef ecosystems. * Careless tourism: Careless boating, diving, snorkeling, and fishing happens around the world, with people touching reefs, stirring up sediment, collecting coral, and dropping anchors on reefs. Some tourist resorts and infrastructure have been built directly on top of reefs, and some resorts empty their sewage or other wastes directly into water surrounding coral reefs. * In the past few decades, the amount of carbon dioxide in the air has increased by one-third. This is harmful to corals because increased amounts of carbon dioxide are dissolving into...
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