Annex 1.
Technical Background
The Seas of East Asia1
The seas of East Asia are defined as the Yellow Sea, the East China Sea, the South China Sea,
the Gulf of Thailand, the Sulu-Celebes (Sulawesi) Sea, and the Indonesian Seas – six large
marine ecosystems (LMEs) that are inter-connected by natural processes, ocean currents, and
shared living marine resources. The aquatic ecosystems and sources of land-based pollution
affecting each regional sea included in this project are described below.
Figure 1: map of East Asia showing land masses and water bodies. Source: PEMSEA
The Yellow Sea, including the Bohai Sea, has a geographically unique floor and complex biotic
communities due to the complicated oceanographic conditions of the area. It is a semi-enclosed
body of water, connected with the East China Sea to the south. It receives large amounts of
sediment, mainly from the Yellow River in the north, and from the Yangtze River in the south.
Pollution in the Yellow Sea originates from land, sea, and air-based sources, and includes
organic matter, petroleum, metals, and inorganic nitrogen. Major pollutants come from
industrial wastewater, domestic sewage, and agriculture.
1
Technical data in this section from www.giwa.net (UNEP / GEF / KALMAR-funded Global International Waters Assessment
reports) and from PEMSEA assessments.
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The most serious source of pollution originates from domestic, industrial and agricultural
pollution discharges into the rivers that discharge to the Yellow Sea. For example, each year
about 200 million tonnes of domestic sewage flows into the Yellow Sea via the Yellow and Liao
Rivers. Agricultural and industrial pollution are also a problem, leading to increased
concentrations of metals, pesticides, and oil in marine organisms. Dumping of solid waste
(garbage, fishing gear) has increased in the region, causing public concern for recreational
activities and tourism.
In the Bohai Sea, whose land basin is home to 35% of China’s population, microbial pollution in
seafood, although still frequent, is decreasing, partly owing to the construction of wastewater
treatment facilities in large cities. However, harmful algal blooms are frequent (5 – 6 times per
year) and eutrophication is considered severe. Large-scale use of pesticides and insecticides in
agriculture and metals from industry has resulted in chemical pollution, with negative impacts on
biodiversity. Solid waste has frequently been reported, which has been significant enough to
deter the public from recreational activities on the beach around the Bohai Sea.
Figure 2: Yellow Sea and Bohai Sea. Source: GIWA.net
The East China Sea is important for its spawning and nursery grounds for many pelagic fish. It
is bordered to the west by China, to the east by the Kuroshio Current, to the north by the Yellow
Sea, and to the south by the South China Sea. It receives a large freshwater input and terrigenous
sediment load from the Yangtze River. Microbial pollution is present in the sea, and harmful
algal blooms have been regularly detected.
The treatment capacity for domestic sewage in China’s coastal cities is only approximately 60%
while the rate of sanitary disposal of household refuse is between 70 – 90%. Both of these
sources of pollution have been found to cause bacterial water pollution. Since the 1980s the use
of chemical fertilizers in agriculture has greatly increased, causing ubiquitous eutrophication.
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The main pollutants carried to the sea by adjoining rivers are COD, nutrients, petroleum
hydrocarbons, and heavy metals.
In 1999, the total discharge of wastewater from Shanghai Municipality, amd Zhejiang and Fujian
Provinces was 5 billion tonnes, of which 2.8 billion tonnes discharged directly into the East
China Sea. Moreover, the dumping of solid waste has been on the increase; in 1999, the total
domestic waste load in Shanghai reached 5 million tonnes, of which only 85% was disposed of
in sanitary landfills. Industrial solid waste reached 156 million tonnes in 2000, although the
percentage of this waste that reached the ocean is unknown.
Figure 3: East China Sea. Source: GIWA.net
The South China Sea, including the Gulf of Thailand, is known as the global center of marine
shallow-water tropical biodiversity: one-fourth of the world’s coral reefs occur in this region,
mangroves are found in great abundance (over 54,000 km2, or 40 % of the global mangrove
area), and seagrass, which is economically important to fisheries and ecologically important to
other species, is highly diverse and well represented in the area. The South China Sea is
bounded to the east by the Sulu-Celebes Sea and Pacific Islands, to the south by the Indonesian
Seas, to the north by the East China Sea, and to the west by the Mekong River.
The health of the South China Sea is in serious decline due mainly to coastal development: the
area’s rapid economic development and population growth are the cause of significant ecological
damage. One of the primary environmental threats is sewage pollution, which affects
biodiversity and fisheries, and has health impacts on downstream populations. Pollution,
overfishing and destructive fishing practices are threatening 80% of the coral reefs in the region,
and endangering seagrass habitats. In much of the region, sewage treatment is superficial at best,
with raw or primary treated sewage discharged directly into water courses. Agricultural
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pollution is also widespread through leaching of fertilizers and pesticides into watercourses.
Pollution of Ha Long Bay (Vietnam) threatens coral reefs, marine life, and the livelihood of
hoteliers and fishermen. In 10 years, 900 million tonnes of sediment polluted by coal mining
have been transported by rivers into the Bay, and close to 9 million m3 of industrial wastewater
contaminated by lead and petrol is discharged into the Bay every year. In Indonesia, municipal
and industrial wastewater is discharged virtually untreated into the waterways causing rapid
deterioration in the quality of river water. Eutrophication hotspots occur in the vicinity of coastal
cities and estuarine areas in non-urban settings where sewage or industrial discharges are directly
dumped because of the lack of sewer connections to centralized sewage treatment facilities. This
is commonplace in Indonesia, Vietnam, and the Philippines. Finally, solid waste (garbage, litter
on beaches) has given rise to public concern regarding recreational use and tourism.
Figure 4: South China Sea. Source: GIWA.net
The Sulu-Celebes (Sulawesi) Sea area is one of the world’s most biologically diverse marine
environments. It lies within the global centre of biodiversity for both terrestrial and marine
species with, for example, more than 400 species of reef-building corals, and 2,500 species of
marine fishes. It contains most of the Philippines islands (excluding the northern islands), the
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northernmost islands of Indonesia, and Malaysian Sabah. In the major urban centers, sewage
treatment is superficial at best, with raw sewage discharged directly into water courses.
Agricultural pollution is also widespread through leaching of fertilizers and pesticides.
Microbial pollution is significant in major urban centers, originating from inadequate sewage
disposal and treatment, which has affected fisheries and human health. The production of
wastewater in the Manila region is estimated at 74 million m3 in 1994, while the volume of
treated wastewater reached just 10 million m3. Eutrophication, although localized, has caused
some paralytic shellfish poisoning in parts of the region. Solid waste has caused moderate
environmental impact in the region. However, there has been severe impact locally, particularly
around the larger cities, where waste management is either poor or non-existent. There is
widespread litter on beaches, high frequencies of benthic solid waste recovery by trawlers, and
frequent reports of entanglement / suffocation of marine species by solid waste.
Figure 5: Sulu-Celebes (Sulawesi) seas. Source: GIWA.net
Finally, the Indonesian Seas are important because they support an extremely high biological
diversity, including both demersal and pelagic fisheries, sharing highly migratory fish resources
(tuna, mackerel, round scad) with adjacent countries. The Indonesian Seas encompass most of
the 18,000 islands of the republic of Indonesia, bounded on their western and northern extent by
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the Bay of Bengal, South China Sea, and Sulu-Celebes (Sulawesi) Seas; on their southern extent
by the north Australian shelf; and northeastern extent by Pacific islands.
Urban expansion and industrialization have resulted in water pollution from industry, sewage,
and contaminated air. Municipal and industrial wastewater is discharged virtually untreated into
the waterways causing rapid deterioration of water quality, particularly in the large urban centers
(e.g. Jakarta, Surabaya). Total discharges of organic water pollution have experienced a rapid
increase from 214 tonnes per day in 1980 to over 537 tonnes per day in 1993. Toxic algal
blooms have caused paralytic shellfish poisoning, and shellfish from most of the Java Sea are no
longer eaten. Eutrophication has severe local impacts e.g. in the Jakarta Bay, where massive
blooms of phytoplankton several meters thick are present for several kilometers offshore.
Overall, solid waste poses a severe problem, particularly in the Java Sea and around cities where
waste management is unable to keep pace with production. Massive amounts of plastic bags and
other waste products flow into Jakarta Bay and foul the Pulau Seribu islands; plastic and other
floating wastes wash ashore on many beaches and clog outboard motors of boats.
Figure 6: Indonesian Seas. Source: GIWA.net
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