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15.15: Coral Reefs

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    Coral Reefs

    Coral reefs are located in tropical settings.
    • Reefs require warm, clear, and shallow water.
    • Reefs also provide sediments and food to deeper water settings.

    Corals are animals (or communities of animals) consisting of polyps – each polyp is an individual coral animals.
    Corals produce calcium carbonate skeletal structures.

    Other reef-forming animals include coralline algae (plants), bryozoans, sponges, mollusks, and many others.
    Animals feeding on reef-forming organisms produce large quantities of sediment (building up reefs).

    Coral reef on a South Pacific atoll
    Figure 15.66. Coral reef

    Importance of Coral Reefs

    Reefs are the largest structures created by living organisms.
    • The Great Barrier Reef in Australia is more than 1250 miles (2,000 km) long and many miles wide.
    • Coral reefs are found in the Florida Keys, Bahamas, many coastal Caribbean destinations. The land itself in these regions consist of ancient coral reef deposits.
    Atolls throughout the South Pacific and Indian Oceans are surrounded by coral reefs.
    • Coastlines of Red Sea, Persian Gulf, and Africa are lined with coral reefs.

    Coral reefs have great diversity of species. Reefs protect shorelines from storm erosion and protect inland freshwater supplies. Coral Reefs are in decline: 30% are healthy today, 41% were healthy in 2000.

    Threats to coral reefs:
    • Hurricanes
    • Floods
    • Coral bleaching
    • Human encroachment and exploitation.

    Atoll community
    Figure 15.67. Atoll reef community

    Hawaiian reef community
    Figure 15.68. Hawaiian reef community

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