Analysis of Structure and Distribution of Coral Reefs

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The modern understanding of coral reefs begins in Charles Darwin’s book, On the Structure and Distribution of Coral Reefs. In this classic book written in 1842, he distinguished three main types of reef: the fringing reef, the barrier reef, and the atoll. The fringing reef occurs near the shoreline and basically follows the profile of the shore. Its stony corals need a firm base on which to establish themselves, and they must compete with many other sedimentary organisms looking for a firm substrate on which to settle. In off-shore waters, that substrate is usually provided by the limestone secreted by earlier stony corals on rock (often volcanic). However, if there is a firm, rocky base present, as in fringing reefs, sedentary rivals can settle in great numbers without waiting for reef-building corals to lay the foundations (Stafford-Deitsch 20). Thus, the stony corals do not have to be the major constituents of the reef. Sponges, soft corals, and corraline algae are abundant throughout the fringing reef. Some of the finest fringing reefs in the world are along the edges of the Red Sea, where the conditions are premier for the growth of the reef. The water is enclosed by desert. Therefore, there is barely any rainfall to wash either the sand or fresh water into the sea. Also, there are very little clouds in the area allowing sunlight to reach the surface, resulting in much warmer water than one might think to find at this latitude. The reefs in the Red Sea are some of the richest and most diverse. If one were to swim over the crest (the open-water edge), one might panic being that the reef drops drastically into unknown depths. Thus, not allowing wave action to stir up much sediment which would damage the reef being that the sediment settles below the reach of the waves. Little sediment at the top of the reef causes water to be clear, maximizing the amount of sunlight that reaches the reef (Stafford-Deitsch 21). The second type of reef according to Darwin is the barrier reef. It is different than the fringing reef in one main way: the area between the living coral of a fringing reef and the shore is the reef flat, but the area between the barrier reef and the shore is a lagoon (Stafford-Deitsch 21). The lagoon is a relatively shallow area of water, only a few meters

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