As one of the major marginal seas in the world, the South China Sea (SCS) is defined by the International Hydrographic Bureau as the semi-enclosed body of water, situated from 3 degrees south latitude between South Sumatra and Kalimantan (Karimata Straits), and to the Strait of Taiwan from the northern tip of Taiwan to the mainland coast of China, and stretching in a Southwest to Northeast direction. The South China Sea is a semi-enclosed sea bordered by the ASEAN member states (Brunei Darussalam, Cambodia, Indonesia, Malaysia, the Philippines, Singapore, Thailand and Vietnam) and China (including Taiwan). For the purpose of discussion the South China Sea also includes the adjoining Gulf of Thailand and the Gulf of Beibu (Tonkin).

 This paper briefly reviews the environment, ecological and oceanographically features of the South China Sea in general, and the environmental issues faced by the regional community in the South China Sea in particular. First, the paper sets out with a brief introduction. Second, it discusses the relevance and importance of the ecosystems and natural resources in the SCS. Third, the paper proceeds to identify the major environmental issues, their causes and implications. Forth, it attempts to sum up the findings from the discussion and offer some recommendations where possible.

　

 The waters and islands of the South China Sea (SCS) form a geographical unit because of their special structure and unique position.¹ The total area of the waters of the Southeast Asia is about 8.9 million km², which account for 2.5% of the World's ocean waters. The SCS has a total area of about 3.5 million km², consisting of the mainland shelf in the north and northeast, and the Sunda shelf including the Gulf of Thailand, in the south and southwest. About 125 major rivers drain 2.5 X 10⁶ km² of catchments area and deliver, water, sediments, nutrients and pollutants to the South China Sea. It lies at the center of the Indo-West Pacific biogeography Province, and is the world's most diverse shallow-water marine area. Such richness in flora and fauna contributes to the area's high natural rates of primary and secondary production.

 The South China Sea not only constitutes the maritime heart of an economically booming region, but also, more importantly, binds southern China to Southeast Asia. The sea is of great importance economically, politically and ecologically to its surrounding nations.

 The significance of the South China Sea is characterized by its environmental and ecological value, living and non-living natural resources, and geo-political and strategic position. First, the region's population is predicted to increase from 475 million in 1993 to 726 million by the year 2025.² The coastal sub-regions of these nations are home to 270 million people, or 5 per cent % of the world's population. The sea produces living and non-living resources for one of the most populous regions in the world. In the Southeast Asian region alone more than 70 % of the population live in coastal areas, and their dependency on the SCS for resources and a means of transportation is high. In turn, the demand and development by the people in the region put enormous pressure on the marine environment and ecosystems.

 Second, the SCS is a unique and integral ecosystem and a repository for valuable natural resources. Forty-five mangrove species out of a global total of 51; 50 of 70 coral genera; 20 of 50 seagrasses species; and 7 of 9 giant clam species are found in the near-shore waters in the region.³ Compared to the Atlantic, the tropical Indo-West Pacific is highly diverse. Only 5 mangrove species and some 35 coral species are found in the Atlantic, compared with 51 mangrove and over 450 coral species are recorded from the Philippines and 200 species from the Red Sea 117 from South East India and 57 from the Persian Gulf.⁴

 Third, it is the world's busiest international shipping lanes. More than half of the world's supertanker traffic passes through the SCS waters. Over half of the world's merchant fleet (by tonnage) sails through the South China Sea every year. Tanker traffic through the Strait of Malacca is more than three times greater the traffic of the Suez Canal, and well over five times that of the Panama Canal, thus making the sea lanes of the South China Sea as one of the world's busiest international sea lanes.

 Forth, the marine and coastal region of Southeast Asia is probably one of the World's most productive areas. Blessed with warm humid tropical climate and high rainfall, coral reefs and mangrove ecosystems flourish along the coastline. Due to the economic benefits that could be derived from the rich and diverse ecosystems, the coastal areas of Southeast Asia are densely populated.

 Fifth, the South China Sea is also an arena for competing territorial claims as well as security interests. It has always been central over the last three decades to issues of political stability and economic development in Southeast Asia and adjacent regions. Today, it is central to environmental sustainability and food security for rapidly expanding populations of the coastal and archipelagos communities.

　

 The South China Sea has a distinctive ecosystem due to three characteristics: archipelagoes and peninsulas; the striking variation in the characteristics of its continental shelf and sea floors; and its unusual monsoon weather patterns of reversing summer and winter rains and winds.

　

 The geology and climate combines to produce a remarkable amount of biological diversity and genetic resources in the South China Sea. There are four major marine ecosystems of particular interest in the South China Sea. These include mangrove forest, coral reef, seasgrass and wetlands. The significance and economic values of these respective ecosystems will be dwelled upon, where possible, in section three of this paper.

 Extensive mangrove forest and coral reefs support several thousand different species of organisms and play an important part in buffering wave impact on beaches, thereby reducing erosion. About half of the coastal population's protein intake comes from the sea. The sea plays an important role in the economies of these nations by providing food and employment for the increasing coastal population. This includes employment in the fishing, aquaculture, transportation, offshore exploration and other marine industries such as recreation and tourism.

　

 As regards resources in the South China Sea, oil is perhaps the most important and attractive ones. The hydrocarbon resources encouraged the littoral states to occupy islands in order to claim rights in future negotiations. Regional as well as much of the international interest centers primarily on this potential hydrocarbon resources. Nonetheless, it is still unclear how great the hydrocarbon resources deposits are. Conflicting assessments have been made of the potential of the South China Sea as an unexplored source of oil and natural gas.

 According to a 1995 study by Russia's Research Institute of Geology of Foreign Countries, the equivalent of six billion barrels of oil might be located in the Spratly Islands area, of which 70 percent would be natural gas. Chinese media outlets have referred to the South China Sea as "the second Persian Gulf," and some Chinese specialists have asserted that the sea could contain as much as 150 billion barrels of oil and natural gas.⁵

 Oil consumption over the next 20 years among developing Asian countries is expected to raise an annual 4% on average, with about half of this increase coming from China. If this growth rate continues, these nations' oil demand will reach 25 million barrels per day, more than double the current consumption levels. It looks obvious that utilizing the oil and gas resources of the South China Sea remains one of the better choices for the nearby large energy-consuming countries, in addition to their oil imports from the Middle East and Africa. Appendices 2, 3 and 4 list petroleum reserves, production and consumption in the region and their comparison with other regions.

　

 The South China Sea is regarded as one of the most important and abundant areas for marine living resources in the world oceans. Shared stocks such as scads and mackerels, and highly migratory species, such as tuna and tuna-like stocks, are the most common and important commercial fisheries. Organic production and nutrient levels are very high in coastal waters, especially around river mouths. For example, the discharge from the Mekong River makes the southern portion of the South China Sea a very rich fishing ground, stretching from the Gulf of Siam to Singapore.

 Fisheries in the Southeast Asian region represented 23% of the total catch in Asia, and about 10% of the total world catch in 1992. Capture fisheries from the South China Sea contribute 10% of the world's landed catch at around 5 × 10⁶ tons/year. From the standpoint of aquaculture, five of the eight top shrimp producers in the world, are countries bordering the South China Sea, namely: Indonesia, first, Viet Nam, second, China, third, Thailand, sixth, and the Philippines, eighth.

 The South China Sea is the main source of protein for the 500 million people who live in the coastal zone of the Sea. The Sea's significance as the main source of protein for the inhabitants of the coastal region is expected to increase with the depletion of the arable land in the littoral states. Fishery resources in the South China Sea region is not only a major component of the economy, but also provides a source of food and employment to the people. Apart from China, Cambodia, and Vietnam, the per capita consumption of fish per year in Southeast Asia countries is above the world average. In addition, fish is the single most important source of animal protein for the people in this region. More than one-half of the total intakes of animal protein by the average Southeast Asian person come from fish.

　

 The relevant economic and ecological values for the four marine ecosystems of particular interest in the South China Sea are shown in the Table 1.

 However, two remarks should be made in terms of the economic value of the ecosystems. First, the figure includes associated values of these ecosystems. For instance, the seagrass values include a figure for commercial fish caught over seagrass. Tourism is a large component of the value of coral reefs. Second, the value figures of these ecosystems in the South China Sea are only estimations, which apparently need to be improved.

　

 The richness and productivity of the natural environment of the South China Sea are, however, increasingly threatened by population growth, excessive harvesting, pollution discharge, and habitat modification. The turn of 21^st century has witnessed a number of development and environmental problems of regional significance in the South China Sea, such as rapid loss of habitat and impairment of the regenerative capacities of living systems. Some of the major environmental issues, including their causes and threats, will be briefly touched upon in the following paragraphs.

　

　

 Mangroves have important economic and environmental values. They are also important because they support productive fisheries (as nursery grounds) and prawn production, and protect coastal areas against the impact of storms, and provide beautiful scenery for coastal tourism. Thirty percent of the world's mangrove forest, covering 50,000 km² of coastal areas, is to be found in the South China Sea region. Mangrove trees are harvested in the SCS region for use as fuel, building materials. Products and ecological services provided by the mangrove systems in the SCS region are estimated to be worth about US$15.984 million.⁶

 Mangroves in the seven participating countries of the SCS region constitute 10% of the current global area of slightly over 1 8 million ha. The total amount of area lost over different time spans (70 years for the Philippines) is estimated to be 4.3 million ha or 24% of the current global mangrove area. The causes for mangrove destruction include urban development and human settlements, woodchip and pulp production, conversion to pond culture, and harvest of products for domestic use. The precise impact of these economic activities in each country is difficult to quantify. Nonetheless, shrimp culture across the region in recent years seems to be the most pervasive economic imperative for mangrove conversion. That being said, the rate of destruction and scale of impact brought by each cause would require further thorough studies (see Appendix 5 for figures on forest destruction in the region).

　

 The South China Sea is also best known for its abundant coral reefs. But like elsewhere, coral reefs in the South China Sea are under severe threat from environmental problems. Roughly thirty percent of the world's coral reefs are found in Southeast Asia. The diversity is very high and the coral reefs are important because they are nursery and breeding grounds for 12% of the world's total fish catch; it has been estimated that coral reefs contribute 30% of East Malaysia's total catch, 25% in the Philippines. The value of the products and ecological services provided by the coral reef systems of the region is estimated at US$ 13,792 million per year (considering one third of coral areas of the South East Asia are located in the South China Sea, and have value of US$ 6076 ha^-1 year^-1).⁷

 Coral reefs have been suffering from degradation mainly due to man-made disturbances. The transboundary issues associated with coral reef degradation include: loss of biodiversity, reduction in reef fisheries, threatened or endangered species, and trade in coral, shells and associated biota. For instance, ninety-five percent of the coral reefs around Hainan Province in China are damaged. The amount of damage to coral reefs along the coast of Vietnam is simply unknown.

　

　

 Seagrasses form a basis for many complex marine ecosystems and provides a valuable nursery and nutrients for commercially important fish and other living resources such as shrimp and crab. Seagrasses also play an important role in the cycling of marine. Another function of seagrass is its ability to bind sediment to the bottom from erosion of the sea floor. When the seagrasses decline the links in the productivity chain are broken and the whole ecosystem would collapse. The value of the products and ecological services provided by the seagrass systems of the South China Sea is estimated at US$ 22,400 ha^-1 year^-1.⁸

 Anywhere between 20 and 50% of seagrass areas in Indonesia, Malaysia, Philippines and Thailand are damaged. As with the other marine ecosystems, the main transboundary effect of this damage is losses of biodiversity and fisheries productivity. The best ways to preserve seagrass is by leaving it undisturbed, mainly by preventing trawling, maintaining water quality by reducing nutrient and suspended solids loads and by using appropriate fishing gear.

 In the South China Sea region, seagrasses are the least studied marine habitats, compared to coral reefs and mangroves. The distribution area of seagrass is not yet known. An assessment of the current status of seagrasses in the South China Sea is based on a few limited studies in some countries.

　

 Wetlands are not unanimously defined and may understand differently.⁹ However, it generally refers to peat swamps, swamps, fens and saltmarshes. Wetlands function as nutrient traps and is the seasonal home to many migratory birds. They have their own suite of animals and plants of great diversity. Wetlands are increasing under threat from land reclamation, land-based pollution, and changes to coastal morphology, bird watching visitors. Some wetlands are used recently for aquaculture. Introduced plants may dominate some wetlands and the classic example of this in many parts of the world is water hyacinth. Finally, the small size and easy access of wetlands make them especially vulnerable to pollution and disturbance.

 The total area of wetlands is about 12.9 million ha in the South China Sea. The value of the products and ecological services provided by the wetlands systems is estimated at US$ 190,726 million per year (the estimated ecological and economic value is US$ 14,785 ha^-1 year^-1).¹⁰

 The loss of coral reefs, mangroves, estuaries and seagrass beds can have serious long-term consequences because of the time these ecosystems need to recover after damage. All countries in the South China Sea region have degraded reefs. The original area of mangroves has decreased by 70% during the last 70 years. With a continuation of the current trend all mangroves will have been lost by the year 2030.¹¹

 For underwater habitats, it is not clear how much damage has been done, as there are no complete studies of underwater habitats.

　

 In the South China Sea, depletion of fish stocks is probably the most important issue here. For an estimated one billion Asians, fish is the main source of protein and fishing supports more people than in any other region of the world. For most states in the region, therefore, the relationship between food securities, ecological damage and conflict is most evident at sea. Competition for fish in Southeast Asia has traditionally been most intense in the Gulf of Thailand. As traditional fishing-grounds are exhausted, competition for the remaining stocks has also intensified in the South China Sea. Fish is and will remain a central issue for the people and states in the region.

 While deterioration of fishing resources is due to a number of factors, the prevailing issue is one of the open access system. Different levels of development in the countries of the South China Sea tend to lead to uneven fishing capabilities. Conflicting territorial claims are also responsible for competition for fishing resources. The pressure on coastal fish stocks has been growing due to new introduction of modem fishing techniques like trawling. At the same time, primitive destructive fishing methods are still used in Indonesia, Vietnam, China and the Philippines, and also to a limited extent in Thailand and Malaysia. The use of explosives and chemicals destroys coral reefs and habitats of species as well as their breeding grounds.

 It is reported that the value of the catch in the South China Sea Region (excluding China) in the early 1990s was US$ 6,800 million, while the quantity of the catch was 9.5 million tones.¹² If the criteria of maximum economic yield were used instead of the maximum sustainable yield, the fishing efforts would be even lower. One study suggests that the fish catch should fall by about 50% from the present level, while the benefit from the reduction in fishing effort would be around 28% of the total value of the present catch.

 Fisheries catch records and stock assessment is not available for the South China Sea It is obvious that monitoring of marine resources and habitats is not adequate. Monitoring should be to determine what the situation is, detect the damage done and to test whether remedial efforts are successful.