The Nature, Structure and Threats facing Coral Reefs

The Nature, Structure and Threats facing Coral Reefs
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Definition of Coral Reefs
In the oceans, there exist calcium carbonate structures secreted by corals. The calcium carbonate forms structures that hold the coral reefs together. Coral reefs are comprised of a collection of tiny animals that belong to the cnidaria group. Unlike other sea organisms that have a soft body cover, corals are covered in a hard exoskeleton. The polyps that live in the corals are therefore well protected from any predators (Dubinsky and Stambler, 2010). Coral reefs occur in different types and they exist in varying ecosystems. The types include barrier, fringing and atoll coral reefs. Coral reefs exist in three zones namely, reef crest, reef lagoon and fore reef that are ecologically or physically linked. Some thrive well in shallow waters, providing a home for various marine organisms (Sale, 2006). Others do well in cold waters and deep waters as well. Coral reefs are beneficial to the ecosystem since they act as tourist attraction and protect the shoreline and fisheries (Levy, 2008). Some coral reefs are very sensitive to the variation in temperatures. The global warming that has resulted to climatic change is therefore a threat to the survival of coral reefs (Isabelle and John, 2006). Human activities such as oceanic acidification also pose a threat to the coral reefs.
The Structure of Coral Reef
Calcium carbonate is the main component of coral reefs. The limestone is absorbed from the surrounding water by coralline algae and colonies of polyps. Most of the component in the foundation of the coral reefs is dead matter composed of dead skeletons of corals (Hopley, 2011). On top of the coral skeletons is the living matter composed of groups of tiny polyps. Most of the coral reefs are beautiful because of the presence of coral polyps that have colorful tentacles. The algae found in the tissues of majority of the animals also contribute to this beauty (Muzik and Katherine, 1992). The size of the coral reefs varies with the species available since they all have different growth rates. The growth rate ranges from one to twenty centimeters per year. The growth rate in the cold waters is mostly slower than the rate of the coral reef found at warmer areas (Spalding and Corinna, 2001). Other environmental factors such disease, sedimentation, sunlight, rising temperatures and salinity of the water also affects the growth rate of coral reefs. As they grow, the corals change to different forms. These forms include free living, encrusting, laminar, columnar and branching (Birkeland, 2006). The morphologies determine the shapes of the coral reefs.
Types of coral reef
The reef slope and the reef flat form are the main zones of the fringing reef found mostly along the shoreline (Spalding, 2004). This type of coral reef has a shallow backreef or none at all, a fact that distinguishes it from the other major coral reefs. It is the most common type and it is believed to be the first one to exist on a landmass (McClanahan, Sheppard, and David, 2000). The barrier reef is the other common type of coral reef. It is very similar to the fringing reef except that it is found further away from the shore. Besides, some of the portions of the barrier reef are deep. Atoll reef is the other main type of coral reef that is mostly found in the Pacific Ocean. It is only found in the subtropics and tropic waters (Soffer, 1995). The reefs majorly take a string-shaped form and they encircle lagoons either partially or completely. The fragile nature of atoll reef makes it impossible to survive in areas where there is heavy erosion. The growth rate of this type of reef is slower compared to other types of reefs. They also thrive in islands but they do not grow to a height of 5 meters (Goodman, Purkis, and Stuart, 2013).
Coral Reef Zonation
The location or zone that a coral reef exists is determined by factors such as temperatures, light and wave energy. Different types are found in various zones because their adaptations to factors such as temperatures vary. On the areas closest to the shore is the back reef or the reef flat. The zones are shallow extending to the reef crest. The conditions in this zone are suitable for coral reefs due to good temperatures and sunlight (Tunnell, Ernesto, and Kim, 2007). The width of the reef flats ranges from a few meters to kilometers while the depth ranges from a few centimeters to several meters. The primary factor that inhibits survival of coral reefs in this zone is its exposure when the tides are not high. A distance from the shoreline is the alga ridge that separates the reef flat from the fore reef. It forms the highest part of the reef but the environment is not very conducive due to exposure during high waves and low tides. The short branching corals are the main coral reefs found in this zone because they are able to withstand strong waves. The reef also acts as the host to various types of algae such as the brown algae.
About 20 meters deep is the buttress zone that may extend to the lagoons. The depth of the buttress is not much but it is not as shallow as the reef crest. It is characterized by high levels of oxygen, high light intensity and temperatures (Montaggioni and Braithwaite, 2009). Fore reef is the other zone where the coral reefs exist and it is the farthest zone from the shore. The limited wave action makes this zone habitable for large coral reefs. Most of the coral reefs are dependent on light thus the deeper the reef the lesser the number of coral reefs found (Karlson, 2009). The depth also affects the temperatures in this zone leading to limited diversity of the coral reefs. Although the zones a as major habitat for marine life, they are endangered by the changing climate (Aronson, 2007). Tropical storms and high tides are on the rise and they are a threat to the survival of the coral reef. The most affected zones are the shallow ends such as the reef crest and the reef flat due to the impact of tides and high temperatures when they are exposed. The seaward slope is mostly affected by factors such as salinity of the sea water.
Ecological benefits of fringing coral reefs that has reef flat Zonation system
Fringing coral reefs act as the home and breeding grounds to a wide range of marine species. The fact that t are found on the reef flat zones aids in the survival of the organisms. This is because the shallow waters in which the zone is enables the coral reef adequate exposure to sunlight and bearable temperatures for marine life (Chapman and Michael, 2000). The fringing coral reef can be said to have an ecological benefit to the economy since it enables the survival of these marine animals thus providing sea food such as crustaceans, and fish (Hart and John, 2002). The seaweed found in the reef is known to aid the pharmaceutical industry in the manufacture of anti-inflammatory and anticoagulant drugs (Perrow, 2002). The marine animals found near the shore in the fringing reef provide beauty products such as jewelry and curio. Fish are also harvested from the reef for trade purposes. The skeletons of marine animals found in the reefs are also important in monitoring the level of pollution in the environment over a particular period of time (Nunes, Pushpam and Tom, 2014). It is therefore evident that the fringing coral reefs should be protected in all ways due to their ecological benefits.
Geomorphic benefits of fringing coral reef
The location of the fringing coral reefs along the shoreline is has a geomorphic benefit of protecting the waters from moving beyond. Due to climate change there are stronger waves, currents and storms which have the capacity to distort the shoreline (Jai, 2010). The presence of reefs along the shoreline ensures that there is no excessive erosion that would affect marine animals. The coral reefs dissipate wave energy thus enabling growth of grass that in turn protects the shoreline from erosion. The mangrove ecosystem also exists as a result of reduction of wave energy from the coral reefs (Balvay, 1995). This further protects the shoreline. The coral reefs are able to build up a land mass that enables various plants to grow thus protecting the shoreline. The status of the coral reefs depends on the activities that are carried out along the coast (Slaymaker, Olav and Christine, 2009). Activities that are harmful to the coral reefs also affect the shoreline indirectly. Any ...