Global Perspective

Coral reef ecosystems are under increasing pressure, and the threats are primarily from human interactions. In some cases, natural disturbances further compound the effects of anthropogenic stress. Of the approximate 600,000 km2 of coral reefs world-wide, it is estimated that about 10 percent have already been degraded beyond recovery and another 30 percent are likely to decline significantly within the next 20 years. In addition, unless effective integrated coastal zone management is implemented, more than two-thirds of the world's coral reefs may become seriously depleted of corals and associated biota within two generations. Coral reef ecosystems at greatest risk are in South and Southeast Asia, East Africa, and the Caribbean, however people have damaged or destroyed reefs in over 93 countries (IUCN, 1993). Rapid population growth and migration to coastal areas where coral reef ecosystems occur exacerbate the problem. The resulting coastal congestion leads to increasing competition for limited resources, to increased coastal pollution, and to problems related to coastal construction. Technology also allows humans to exploit the reef with mechanical dredges, hydraulic suction, dynamiting, and large-scale poisoning. More specifically, the major causes of coral reef ecosystem decline include:

  • The overexploitation of reef resources (fish stocks have declined significantly in many reef areas, especially near centers of human population);
  • Excessive domestic and agricultural pollution; and
  • Poor land use practices that increase sedimentation.

Millions of people depend on reefs for food and livelihood. Reefs also create sheltered lagoons and protect coastlines and mangroves against wave damage. Mangroves in turn protect reefs from sedimentation and eutrophication. Mangroves and seagrasses also play an important role in coastal protection and provide spawning and nursery areas for reef and offshore fishes. The economies of many atoll nations are based on marine resources. In the Pacific, over 2.5 million people live on islands built by or surrounded by coral reef ecosystems. Over 300,000 people live on coral islands in the Indian Ocean and many more in the Caribbean. Coral reefs provide 10-12 percent of the harvest of finfish and shellfish in tropical countries and about 20-25 percent of the fish catch of developing countries. As much as 90 percent of the animal protein consumed on many Pacific islands comes from marine sources (IUCN, 1993). The potential sustainable yield of fishes, crustaceans, and molluscs from coral reefs could be 9 million metric tons -- 12 percent of the world fisheries catch. At the present time only a fraction of this potential is realized. Even more important than the actual monetary amount is the people who benefit from these fisheries as they are a major source of income and employment in areas where few employment alternatives exist. Tourism and recreation use of reefs on a large-scale are recent developments. Numerous figures are available describing tourist revenue from coral reefs, but few are clearly defined or comparable. The coral reefs of Florida alone have been estimated to generate about US $1.6 billion annually from recreation uses. Figures for developing world countries are better expressed in other ways -- for many Caribbean countries tourism is now the key economic sector, often providing over 50 percent of GNP, and growing very fast. In 1990, Caribbean tourism earned US $8.9 billion and employed over 350,000 people. Divers and other special-interest tourists may account for over one-fifth or more of this total. A 1981 Island Resources Foundation cost benefit study of the Virgin Islands National Park found that benefits (US $23.3 million, of which US $20 million were indirect) were more than ten times larger than costs (US $2.1 million), which clearly illustrates the economic benefits of marine protected areas (Dixon, 1993). In Thailand, about 5,000 small boat and dive shop operations are dependent on reef tourism (Spencer Davies and Brown 1992). Collecting aquarium fish and live corals for European and North American markets has developed into another lucrative but sometimes damaging industry. Harvesting often kills organisms not intended for collection and more than 50 per-cent of the fish collected die before reaching market. Tourism can be an environmentally friendly way of generating income from coral reef ecosystems, but only when resort development and operation are carefully controlled. Unlimited collecting, sport fishing, and accidental damage by waders, swimmers, and boat anchors can all degrade the reefs that earn tourist dollars. Allowing sewage and other wastes from tourist facilities to pollute reefs or siting resorts so that beach erosion increases, can be even more degrading to the health of the reef than the direct damage caused by visitors.

Information for accurately evaluating the condition of the world's reefs is critical for effective management. However, in many cases this knowledge is lacking. Many countries with coral reef ecosystems need training and capacity building to apply scientific management principles. Non-governmental organizations (NGOs) have and will continue to play a major role in coral reef ecosystem conservation. Since most countries have not incorporated integrated coastal zone management, economic and environmental decision making has not been fully integrated to protect and sustainably use coral reef ecosystems.

The Land-Ocean Interactions in the Coastal Zone (LOICZ) project of the International Geosphere-Biosphere Programme (IGBP) held a meeting in the Philippines from 24-27 April, 1995. A major concern of this international project is determining the role of coastal processes in global climate change. Discussions highlighted the need to better understand coral reef systems, which may play a crucial role in the circulation of CO2 and other gases. There is a need to better understand human impacts on reef functions, the responses of reefs to changes in sea level, and the interactions between coral reefs and other ecosystems. In particular, more needs to be known about interactions with adjacent land masses, such as through the hydrological cycle. Concern was raised that rising sea level would have very serious consequences for nations situated on low, coral reef archipelagos, such as the Maldives. An important workshop on these issues is expected to take place in Japan within the next several months.

Further activities will include the International Coral Reef Symposium (ICRS) to be held in Panama in mid-1996. This is one of a series of symposia held periodically and serves as a major forum for exchanging information on the science and management of coral reefs, particularly among developing country scientists. The 1996 ICRS will mark the onset of the Year of the Reef. The latter will involve a variety of national and international activities aimed at improving coral reef management. Among the more important activities for which support is being sought will be coordinated surveys of coral reefs around the world and the establishment of a global coral reef monitoring program. These activities will be extremely important in efforts to determine the status of the coral reefs of the world and to determine how global changes will affect people dependent on coral reefs.

A project which is specifically designed to provide centralized access to information from these and other coral reef programs is ReefBase: the International Database on Coral Reefs. This project of the International Center for Living Aquatic Resources Management (ICLARM) seeks to gather a broad range of information about the status of the world's reefs from papers, reports and inputs from monitoring projects. The project includes an activity of the World Conservation Monitoring Center to digitize maps of coral reefs and to make them available through the database. The ReefBase project serves as a medium of information exchange for scientists, particularly those in developing countries with limited library facilities, and as a conduit of useful information to coastal planners and managers.

Some initial results of the ReefBase Project are displayed in Maps 6-11. Each of the maps shows the countries or island states of the world with direct responsibility for coral reefs in dark green, and countries with less developed coral communities in light green. Maps 6-10 show the global dispersion of five forms of stress on coral reefs. These maps are not comprehensive, but serve to indicate the scale of each problem.


The coral-eating crown-of-thorns starfish Acanthaster has had many outbreaks in the past decade throughout the Indian Ocean and Southeast Asia. The frequency of these often devastating outbreaks may be increasing, possibly a result of human activities.

Map 6: Selected outbreaks of Acanthaster -- the coral-eating crown-of-thorns starfish.

click on map for larger (~40K) version


Bleaching of corals involves the expulsion by the corals of the single-celled algae which normally live in their tissues, and on which they depend as a major food source. Increasing cases of widespread bleaching may be a consequence of global warming.

Map 7: Selected episodes of widespread coral bleaching. Increasing frequency of bleaching may be related to global warming.

click on map for larger (~60K) version


A map of sedimentation problems combines effects of increased runoff from deforestation, the dumping of mine tailings, and sediment from a variety of construction projects. Sediment in low amounts reduces coral growth and resilience to stress. In large amounts, particularly during storms, sediment can bury corals or whole coral communities.

Map 8: Selected reports of damage to reefs by sedimentation, including that related to run-off from land and that associated with construction activities damaging to reefs.

click on map for larger (~60K) version


Pollution is a rising problem, particularly that from urban centers and organic pollution from coastal villages and tourist facilities. Organic pollution often enables seaweed to overgrow coral communities, and there is a need to develop more practical, low-cost methods to reduce this pollution in coastal situations.

Map 9: Selected reports of pollution affecting reefs. Organic pollution from crowded coastal villages, urban centers, and tourist facilities is increasing very rapidly.

click on map for larger (~60K) version


Blast fishing is widely dispersed and rapidly growing. As with other forms of destructive fishing associated with the condition known as Malthusian overfishing, such as poisoning and muro ami fishing, the problem tends to increase as human populations increase, resulting in increasingly desperate competition for reef resources. To date, more than 40 countries are known to have problems with blast fishing on coral reefs, and more than 15 have reported cyanide fishing.

Map 10: Selected reports of blast fishing. Increasing human densities along fringing reefs and limited reef resources leads to the increasing use of destructive fishing methods.

click on map for larger (~60K) version


Map 11 shows the marine protected areas covering coral reefs which are currently recognized by the World Conservation Monitoring Center (some 353 worldwide). The size of the dots is misleading, as the total area enclosed by these reserves and parks is extremely small relative to the coral reef area of the world (less than 1/1000th). There are other protected coral reef areas which do not yet meet the criteria used for this list. However, the total size and dispersion of all protected reefs combined, even if they were effectively managed, is currently inadequate to preserve the biodiversity and fishery production of reefs in any part of the world outside of eastern Australia. A more reasonable system would protect at least 20 percent of all coral reef areas in combinations of large and small reserves and parks.

Map 11: Marine protected areas covering coral reefs meeting specific criteria of the World Conservation Monitoring Center.

click on map for larger (~80K) version


International legal protections and cooperative frameworks for coral reef ecosystems take numerous forms, addressing such problems as coral trade, marine protected area designation, and land-based and sea-based pollution. For example, many, but not all, species of coral are listed in Appendix II of CITES, which requires them to be accompanied by permits for importation. A very limited number of coral reef sites are listed in such treaties as the World Heritage and Ramsar Conventions.

Human Consequences

Degradation of coral reef ecosystems would have significant impact on world food sources, and long-term negative economic impacts on fishery and tourist industries, and a devastating effect on millions of people around the world for whom coral reefs represent the primary source of livelihood.

Preliminary Recommendations for Action

Integrated Coastal Zone Management

  • Immediate governmental priority must be placed on the development and implementation of integrated coastal zone management strategies to effectively manage the coral reef ecosystems of the world. These strategies should address human activities in the coastal watershed and marine area and involve combinations of:

    Public education, including education in the use of traditional forms of reef tenure and management and education on sustainable use practices;

    Community development;

    Economic incentives and alternative income generation;

    Global or regional legal instruments should be used in an efficient manner as well as strengthened for the conservation and sustainable use of coral reef ecosystems;

    Institutional restructuring;

    Well-managed marine protected areas;

    Regulation and enforcement of reef resource exploitation;

    Management of tourism and recreational activities (e.g., education programs, installation of mooring buoys);

    Management of land-based activities and coastal development, e.g., using environmental impact assessments (EIA), wise siting of facilities; and

    Coral reef ecosystem monitoring, mapping, database creation, and restoration.

    Combining these management techniques is critical for success. If used alone, these techniques tend to be ineffective over the long term. They must be strongly supported at scales ranging from the village to nation, and often at the regional scale as well. They must be oriented toward long term sustainability of reef resources, and designed to be adaptive to different cultures/governments and changing situations without compromising effectiveness.

    There are a number of examples from around the world of good, economically viable, and environmentally sustainable uses of coral reefs -- these come from traditional and indigenous resource-use systems and from western coastal zone management and protected areas systems. These examples should be studied, adapted, and used around the world to further promote sustainable use and conservation of coral reefs in a manner that should enhance rather than hinder economic development (White et al., 1994).

  • A worldwide system of marine protected areas should be established to encompass at least 20 percent of all reefs. This should include widely dispersed small reserves involving up to a few tens of square kilometers, and several strategically located large reserves at the scale of hundreds or thousands of square kilometers. Examples of the latter would include the existing Great Barrier Reef Marine Park, as well as proposed parks encompassing the Chagos Archipelago in the Indian Ocean and similar systems in the Pacific and Caribbean regions. Ideally, these protected areas should form part of wider coastal zone planning initiatives encompassing the reef systems of entire countries and integrating the needs, of local peoples, commercial fisheries, tourism, terrestrial construction and agriculture needs and nature conservation.

Capacity Building

  • A concerted effort must be made to enhance the capacities of countries, particularly developing countries, responsible for coral reefs to conduct scientific research and to design and implement informed, effective, integrated management systems. This implies not only the transfer of information, but more importantly, the exchange of experiential learning among developing countries.

Improved Scientific Understanding of Coral Reef Ecosystems

  • Efforts must be enhanced to survey the coral reefs of the world to provide information on their ecological and management status; and
  • Scientific management information is needed for:

    Understanding the relationship of natural to anthropogenic impacts;

    Conducting damage assessments;

    Understanding coral recruitment and the maintenance and renewal of reefs;

    Understanding water circulation patterns to determine the distribution of reefs and the fate of pollutants; and

    Developing an improved scientific concept of what constitutes a healthy reef so it will be possible to gage changes on impacted ecosystems (Ginsburg, 1994).

  • So that the health of coral reef ecosystems can be monitored in a systematic manner, the Intergovernmental Oceanographic Commission (IOC) Global Coral Reef Monitoring Network should be established and maintained. This will provide valuable data to the larger Global Ocean Observing System. This information will not only help local authorities monitor the health of their coral reef ecosystems and improve management capabilities, it will also provide a perspective on the condition of coral reef ecosystems and climate change world-wide.


In conclusion, the coral reef ecosystems of the world represent an important resource, both in terms of global biological diversity and with respect to the well-being of the people who live near and depend upon them. Many are at risk and need better management. The future actions of managers, scientists, national bodies, local communities and international programs will be critical in saving these natural treasures (IUCN, 1993).

State of the Reefs * May 1995

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