Coral reefs

Coral Reefs,
The City Under the Ocean
Nick Gray
Mr. Mullen
English 1102
27, February 1999
Coral Reefs:
The City Under the Ocean.

It was a hot sunny day off the Bahamas shoreline when my family and I went snorkeling for the first time. We took a boat out to the coral reef and dove down to find an underwater beauty. There were many different forms of life including colorful fish, different types of coral, white sand and lots of activity. The large schools of neon colored fish swam so close you could almost reach out and touch them. It was so beautiful I could explore the reef for hours.

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The marine world is a vast ecosystem depending on many communities existing in harmony. Marine Biology can be branched off many ways. Coral reefs are one of the largest branches and play a major role in the marine ecosystem. They are necessary to many forms of marine life, consequently the reefs are in great danger due to mankind and natural destruction. There are scientists, students and other interested parties working to preserve the reefs.

The coral reef is an elevated part of the ocean floor in relatively shallow waters. Reefs are formed by rock like accumulation of calcareous exoskeletons, calcareous red algae and mollusks. They have built up layer by layer of living coral growing upward at rates of one to one-hundred centimeters per year. The reefs live in tropical regions starting about 30 north and south of the equator. (Darwin) About 200 to 450 million years ago the soft bodied invertebrates evolved making the coral reef the oldest and largest living community on earth. The inner layer of the reef is composed of non-living matter and the upper layer is composed of transparent polyps that grow on the remains of the once living polyps. The polyps are remarkable creatures that range in size from a small seed to as big as a lily pad and secrete calcium carbonate that forms tiny cup shaped homes. (Hinrichsen p. 554 – 555)
The reefs play a large ecological role by cycling nutrients from swamps and sea grass beds to open ocean fisheries. Many plants and animals living on the reef produce chemicals used in medicines and pharmaceuticals. The reefs bear many sources of animal protein such as fish, shell fish and mollusks for more than one billion people. They also help to stabilize and prevent shoreline erosion. (Hinrichsenp.555)
There are many types of coral reefs that make up the reef population. Three main categories of reefs are fringing reefs, barrier reefs and atoll reefs. Fringing reefs exist off the shore of an island or mainland containing no body of water between the reef and land. Further off the shore, barrier reefs exist with a channel between the reef and shore. The Great Barrier Reef consists of a chain of coral reefs in the Coral Sea near Australia’s northeast coast. Extending about two thousand kilometers from Mackay, Queensland to the Torres Straight makes this the largest deposit of coral in the world. Some northern areas of the reef are as close as 16 kilometers to the shore and reach a width of about 240 kilometers. The reef supports more than 1000 species of fish and many other organisms. (“Great Barrier Reef”) Atolls are narrow coral islands typically horseshoe shaped with a shallow lagoon. (Hinrichsen)
There are many other types of coral organisms varying in size, shape and color.These include staghorn coral, bulging brain coral, button corals, fire corals, lace corals, bead corals, organ pipe corals and vase corals. The name of the coral is indicative of the shape it produces. Another key reef species are the sponges. The sponges act as a lung for the reef, clinging and recycling the water. The reefs depend a great deal on the abundance and coexistence of the sponge. (Hinrichsen)
The coral reef is endangered in many aspects from both mankind and nature itself. Each year, thousands of tourists visit the coral reefs hoping to take back a piece as a souvenir. “Ten percent of the reefs are already degraded beyond recognition, and thirty percent are in critical condition. Clive Wilkinson, a coral reef expert at the Australian Institute of Marine Science in Townsville, has concluded


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