Conservation of the Coral Reef
Coral reefs occupy less than 1% of the marine environment, but they are home to more than 25% of all known fish species. But because the majority of coral reefs are located in regions known for extreme poverty and high population growth rates, they are particularly vulnerable to degradation.
When a polyp dies, the limestone cup that housed it remains until the next polyp comes to live in it. This material builds up, with the living corals growing on top of the skeletons of past generations. They grow very slowly, so a careless kick from a snorkeller or diver can destroy decades of growth.
Coral Habitats Requirements
1. Although various types of corals can be found from the water's surface to depths of 19,700 ft. (6,000 m), reef- building corals are generally found at depths of less than 150 ft (46 m), where sunlight penetrates. Because reef- building corals have a symbiotic relationship with a type of microscopic algae, sunlight is necessary for these corals to thrive and grow.
a. Reefs tend to grow faster in clear water. Clear water allows light to reach the symbiotic algae living within the coral polyp's tissue. Many scientists believe that the algae, called zooxanthellae, promote polyp calcification. See symbiosis for more information on this algae and its relationship with coral.
b. Light-absorbing adaptations enable some reef- building corals to live in dim blue light.
2. Reef-building corals require warm ocean temperatures (68 to 82 F, or 20 to 28 C). Warm water flows along the eastern shores of major land masses.
3. Reef development is generally more abundant in areas that are subject to strong wave action. Waves carry food, nutrients, and oxygen to the reef; distribute coral larvae; and prevent sediment from settling on the coral reef.
4. Precipitation of calcium from the water is necessary to form a coral polyp's skeleton. This precipitation occurs when water temperature and salinity are high and carbon dioxide concentrations are low. These conditions are typical of shallow, warm tropical waters.
5. Most corals grow on a hard substrate.
Coral reefs are subject to other serious threats, including:
- Pollution from sewage that is pumped into the sea, or from chemicals (for example, fertiliser, industrial waste, oil and desludge from ships) that seep into the sea.
- The developmenton land that causes silt (from activities such as dredging, deforestation, etc) to wash into the sea. This silt not only reduces the amount of light that passes through the water to the reefs but also settles on them, thus smothering them and stopping new coral from growing.
- Destructive fishing methods such as blasting (by exploding a bomb in the water) and the use of sodium cyanide (which stuns the fish and enables them to be easily collected, primarily for restaurants and aquariums) not only destroy reefs but their inhabitants as well.
- Unmanaged tourism activities, while bringing much needed revenue, can have a negative impact. An increase in tourists can lead to an increase in coastal development, which in turn leads to increased siltation and sewage pollution.
1. Corals should not be collected, either alive or dead. The United States federal government has prohibited the removal or destruction of corals from all areas of the continental shelf within a three-mile limit.
2. In waters off Florida, collection of dead coral is regulated by the Florida Marine Fisheries Commission. This Commission is working to phase out dead coral collecting by 1994.
3. Hawaii, Guam, and Puerto Rico have banned the collection of all hard corals, both living and dead.
4. The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) regulates international trade of certain animals and plants. More specifically, the Convention regulates the import, export, re-export, and introduction from the sea of certain plants and animals. Species for which CITES controls trade are included in one of three appendices. These appendices classify animals in terms of their vulnerability. Many corals are classified by CITES as Appendix II species. These species are not necessarily threatened with extinction but may become so unless their trade is strictly controlled. Appendix II includes the following corals:
a. All corals in the order Coenothecalia (Indo- Pacific blue coral).
b. All corals in the family Tubiporidae of the order Stolonifera (organ-pipe coral).
c. All corals in the order Scleractinia (reef- building corals).
d. All corals in the order Antipatharia (black corals).
The establishment of marine sanctuaries or preserves may help ensure the availability of this ecosystem in the years to come. The Great Barrier Reef Marine Park was established in 1975.