Abstract
Coral reef depletion is not a new phenomenon as coral reefs in most parts of the world have gone through substantial alterations in their history. As early southeast the 1870s, coral reef mortality existed in many places although the trend of depletion has Southeast increased in recent years. Natural disturbances such as hydrographic disturbances, unusual drops of sea levels, rain, and storms, as well as earthquakes have for a long time altered coral reefs. In Australia for example, recurrent cyclones on the Great Barrier Reef found at Heron Island, led to the complete removal of the coral cover between 1967 and 1992. But even with the occasional disappearance of coral reefs over time, reasonable recovery of corals has also been taking place in some places (Valiela, 2006, p.23).
Introduction
A coral reef is a colony of minute sea animals by the name of polyps, living together by establishing themselves upon suitable surfaces that meet the requirements for their survival. These polyps measure about 2 to 3 cm in length and obtain their food from minute organisms such as plankton, algae, and larvae. Minerals obtained through the food enable their progressive, though very slow growth measuring about 1 cm in a whole year. Coral reefs are tropical features occurring over a certain latitudinal range of 30 degrees North and South of the equator but only grow in those areas that meet the requirements for their survival, such as warm waters with temperatures not getting below 18 degrees centigrade. The largest coral reef in the world is the Great Barrier Reef in Australia which stretches out for a lengthy 2000 km, often breaking in some places, and running parallel to the continent’s eastern coast (Bermingham & Digby, 2000, p.135-136).
Coral reefs cover just about 0.2 % of the total ocean floor but have been identified as very important systems for human life’s existence and development. About 25 % of all marine species for example depend on coral reefs for their survival and certain species of corals have also been found to contain medicinal properties. Coral reefs also provide the raw material for producing building material, shells and stony coral for making ornaments, and black coral for making jewelry. Disintegrated coral shells help in the creation of sandy beaches while some coral reefs have provided sheltered harbors. Coral reefs are a recycling base for carbon dioxide especially in seawater and also help to control erosion along coat lines (Bermingham & Digby, 2000, p.136). Coral reefs make up about one-third of the world’s coastal tropical coastlines providing them with protection from extensive wave damage. These reefs have also played a very essential role in providing a worldwide chemical balance in the oceans, taking up about half of the calcium deposits that get into the sea every year. The coral reef ecosystem is biologically very diverse and productive, ranking among the highest productive ecosystems of the world with several species co-existing per hectare (Birkeland, 1996, p.1-4).
Coral reef depletion
The problem of coral reef depletion has become a worldwide crisis and although human activities have largely been blamed for the loss of reefs worldwide, there are also natural factors such as global climatic changes, coral predators, and worsening coral diseases. Coral reefs most prone to depletion are those in the Caribbean, East Africa, and South and Southeast Asia although reefs have also been largely destroyed in many other parts of the world (Gustavson, Huber & Ruitenbeak, 2000, p.3). In many areas of North and East Asia for example, coral bleaching and severe typhoons have hit some of these areas. Natural disasters such as the tsunami have destroyed vast stretches of coral reefs especially along the Indian Ocean regions of Indonesia, Thailand, Burma, and Malaysia, and in some of these coastlines; depletion has been very severe (Cote & Reynolds, 2006, p. 4, 12).
Coral reef formation takes place in environments where temperature variations are very minimal over a long period. For about 18,000 years, tropical oceans have experienced little variation in water temperatures, and the geological history of corals, therefore, makes them very sensitive to above normal temperature changes that have become a common phenomenon in recent times. Greenhouse gases especially carbon dioxide have led to global warming and raised temperatures in sea and ocean waters causing coral bleaching. Since the 1980s, coral bleaching has become a very common phenomenon, leading to the complete death of reefs in some parts of the world. In 1998, most coral reefs in the world suffered coral bleaching due to the warming of ocean waters that was largely a result of the widespread El Nino-Southern Oscillation (ENSO but differences in duration of exposure and also the coral composition of affected reefs caused varied effects in different places (Valiela 2006, p.23, 25; Birkeland, 1996, p.50,52)
Increased population growth around coastal areas which has been accelerated by migration to these areas, has probably been the worst cause of coral reef depletion and has exacerbated the problem. Vast areas of mangrove forests have been cleared to pave the way and provide materials for the urban and industrial expansion of coastal towns, as well as in the construction of tourist resorts and transport systems. These mangrove forests and swamps provide enumerable protection to coral reefs against sedimentation as well as providing good nursery and spawning environments for offshore fishes and reefs. Construction also uses rocks, limestone, and sand mining from coral reefs, a kind of mining that is usually done beyond a sustainable scale. Advanced technology has given rise to very destructive methods of coral exploitation such as hydraulic suction, poisoning, mechanical dredges, and dynamiting. The environmental disturbances from massive human activity have also led to increased frequency of plagues and diseases that affect coral predators (Gustavson, Huber & Ruitenbeak, 2000, p.3; Cote & Reynolds, 2006, p. 4).
The coral reef ecosystem is home to varieties of fish species, a factor that has made reefs prone to extensive human interference through fishing. Fish provides food and is also a source of income for many coastal people and as a result, overexploitation has taken place on a very large scale, especially in poor countries. Competition for marine resources has given rise to destructive methods of fishing such as cyanide and bomb fishing which have resulted in over-fishing. Overexploitation destroys the natural food chain in seawater, highly affecting coral reefs due to overgrowth of macro-algae and causing a high preference of coral predator plagues. Trawl fishing breaks coral reefs because the metal wheeled nets are dragged along the sea bottom (Pickering & Owen, 1997, p.373; Bermingham & Digby, 2000, p.137).
Facilities constructed to cater for tourist accommodation and other tourist activities have been put up at the expense of the natural habitat. Sewage from the tourist resorts running directly into the sea and ocean waters leads to the overgrowth of algae that the diminishing fish population is unable to cope with. Other tourist activities that have affected reefs are walking on overexposed reefs causing them to break, scuba diving, boat moorings, as well as collecting memorabilia. (Bermingham & Digby, 2000, p.137). Harvesting live corals for North American and European markets has become a lucrative industry but one that can also get very destructive. The harvesting methods cause death to many other organisms along the path while some of the harvested products may not even make it to the destined markets alive. Sportfishing, unlimited collection of corals, boat anchors, and accidental damages by swimmers and certain birds such as waders are also major causes of depletion (Gustavson, Huber & Ruitenbeakk, 2000, p.4; Birkeland, 1996, p.4).
For coral reefs to well, they require a good supply of food and oxygen to the warm waters in which they grow, and such waters need also be free from silt and mud sediments. Deforestation especially on steep terrain causes very intense soil degradation, often resulting in mudflows and landslides. When these sediment loads get washed into the rivers, they subsequently drain into adjacent coastal seas and oceans, affecting reef-forming corals that are very sensitive to high concentrations of sediments in the water as they curtail light penetration, thus slowing down the process of coral growth. Cloudiness in the water interferes with the formation of calcium carbonate shells that are a habitat for coral polyps (Pickering & Owen, 1997, p.14, 350). Developing nations are worst hit by the exploitation of resources such as forests for very short-lived economic gains. Wastewater discharge from tankers, cruise ships, yachts, spills, or leaks from oil refineries as well as ship anchors and groundings have also been a great threat to coral reefs (Walker, Salt & Reid, 2006, p.65).
Possible solutions to coral reef depletion
Today’s coral reefs are therefore in greater danger of depletion due to the combined forces of pressure from global climatic changes and widespread destruction of the natural habitat. A degraded coral reef system would impact very negatively on tourism, fishing, and food sources and lead to very devastating economic and social impacts on the lives of millions of the world population. Considerable effort must therefore be made to conserve and ensure safe continuity of this very natural resource. Because coral reefs are an international natural resource and are not confined to any political boundaries, conservation of the same will therefore require the future combined effort of national bodies, local communities, scientists, managers as well as international programs. Management of coral reefs should be a collective effort, inviting international collaboration between states. Because developing countries are most affected by depletion, considerable effort should be made to enhance their involvement in reef conservation by encouraging them to undertake scientific research and also design and put to practice integrated systems of coral reef management. This will involve the exchange of information and experiential earning among coral reef countries in the developing world (Gustavson, Huber & Ruitenbeak, 2000, p.12; Bermingham & Digby, 2000, p.142).
Due to their sensitivity and fragility, there is a dire need for the proper management of coral reefs. A recent popular approach to the proper management of coral reefs is the creation of well-run marine parks that charge entry and other fees for access to such parks. People living in coral reef areas should also be made aware of the value and importance of coral reefs as a natural resource. Public education for both locals and tourists is very essential whereby locals are taught to value the existence of coral reefs and tourists are taught how to handle themselves in such environments to maintain minimal interference with the ecosystem. This can be done by setting up information centers, conducting educational campaigns, and incorporating coral reef education in school curricula. Proprietors of the tourist industry should take more responsibility for the very resource that if well managed will continue to provide the necessary income. But lack of funding and proper public education is a serious setback in such a process. When planning land use, governments in coral reef-rich countries should make consideration of the reefs by assessing what impact any development may have on the reefs and taking the necessary action (Bermingham & Digby, 2000, p.141, 142).
Destructive fishing methods in coral reef waters should be regulated and fishing in such areas be carried out at sustainable levels, an action that should be a priority in all countries that have coral reefs. This will help to maintain a balance in coral reef ecosystems by ensuring that certain breeds of fish and other organisms are not wiped out. Protection of breeding stocks improves fish yields and helps to control over-fishing. Utilizing underexploited varieties of other coral life such as sea mollusks and cucumbers will also help to maintain fisheries for a long time. If the areas restricted to fishing are increased to a considerable size, a natural regeneration of stressed critical fish species is allowed to take place and this will enhance the springing back of stagnated coral reefs. Perhaps other economic activities should be introduced in coral reef areas to create other sources of employment so that too much pressure is taken off fishing (Cote & Reynolds, 2006, p.34; Walker, Salt & Reid, 2006, p.72).
Perhaps, proper land use both in the country and coastal areas will play a great role in helping to protect coral reefs. Re-a forestation will help to control sediment runoff into the rivers and oceans. Engineering approaches like those being experimented with within the Indian Ocean after massive tsunami destruction in 2004 are another possible solution to coral reef depletion. This involves the construction of very small artificial reefs and the transplanting of corals. But this is a small-scale intervention process and cannot help much due to the increased threat of coral reef depletion worldwide (Walker, Salt & Reid, 2006, p.72).
Conclusion
Today, there are very few coral reefs, even in very remote areas of the world that remain unaffected by pressure from human activities because over-fishing has affected all valued organisms like sharks and lobsters. Coral reefs are self-repairing natural systems and if given enough opportunity to do so, then future generations can be sure to reap from coral reef environments (Gustavson, Huber & Ruitenbeak 2000, p.4).
References
- Bemingham, S. and Digby.B. (2000). Changing Environments. Portsmouth: Heinemann.
- Bikerland, C.S. (1996). Life and Death of Coral Reefs. Warren: Springer.
- Cote, Isabelle M and Reynolds J.D. (2006). Coral Reef Conservation & Fisheries Conservation Foundation. Cambridge: Cambridge University Press.
- Gustavson, K, Huber R.M., Ruitenbeak H.J. (2000). Integrated Coastal Zone Management of Coral Reefs. Washington DC: World Bank Publications.
- Pickering, K.T and Owen L.A. (1997). An Introduction to Global Environmental Issues. London: Routledge.
- Valiela, I. (2006). Global Coastal Change. Oxford: Blackwell Publishing.
- Walker B.H, Salt D.A. and Reid W.V. (2006). Resilience Thinking: Sustaining Ecosystems and People in a changing world the Southeast. Washington DC: Island Press.