Marine and coastal areas
With more coastline than any other region in the world (some Pacific islands consist of nothing more than a coastal zone), the region's rich marine resources have for long been central to its development. At the turn of the century, many countries relied almost exclusively on inland and marine fisheries as their sole source of protein and, in some cases, foreign exchange. In the latter half of the century, the rapid expansion of fisheries, coupled with population and industrial growth, resulted in increased migration to coastal cities and the expansion of coastal settlements. Today, about one-quarter of the world's 75 largest cities are situated along the region's coastline. This has resulted in increased domestic and industrial effluent, more areas of landfill, increased dredging, and the erosion of coastlines and coastal habitats. In addition, pollution from upstream, and the expansion of aquaculture production at the expense of mangrove forests, have further degraded marine and coastal resources.
In many parts of the region, economic development has been most active in coastal zones, putting enormous pressures on coastal ecosystems. For example, during the 1960s, heavy industries concentrated along Japanese coastal areas caused extreme water pollution, especially in semi-closed areas, which damaged fishery resources and resulted in red tides (JEC 1997). Strict laws and standards since the 1970s have successfully improved the quality of coastal waters, although eutrophication in areas such as Tokyo Bay is still serious despite the development of sewage systems. In addition, impoverished coastal inhabitants have exploited coastal resources with little regard for sustainability and this has resulted in the loss of critical ecosystems. Coastal erosion, resulting from increased land subsidence from groundwater extraction, and off-shore mining of sand and dredging are two other notable problems in some places. Long stretches of Australia's 70 000-km coastline are far from major population centres and among the least-polluted places on Earth. However, human activities have caused extensive losses of saltmarshes, mangroves and seagrass beds, particularly near urban areas (Commonwealth of Australia 1996).
Marine-based tourism is also increasing. In Maldives, for instance, marine-based tourism now contributes more than 19 per cent of the country's GDP and 30 per cent of government revenue (Government of Maldives 1998). It has also caused environmental degradation, particularly through the construction of hotels, beach clubs and marinas involving infilling, dredging and the resuspension of contaminated silts.
The introduction of modern fishing has transformed fisheries in the region. Marine fisheries production increased by an average of 2.9 per cent a year during 1975-95 (see graph). By 1990, the region accounted for 38 per cent of the world marine fish catch and 8 Asia-Pacific countries were among the world's top 15 fishing nations. However, by the early 1990s, traditional marine fish stocks had reached full exploitation in many areas (FAO 1991, ASEAN 1997) and overfishing was threatening the diversity and quantity of fish (UNESCAP/ADB 1995). Stocks that have been severely affected include all the assessed fish stocks in the Northwestern Pacific off the Asian coast and Skipjack tuna and inshore stocks of demersal fish off Southeast Asia (FAO/RAPA 1994). In Australia, most major seafood species are now fully fished and some species, including the southern bluefin tuna, have been overfished (Commonwealth of Australia 1996, BRS 1997). The world's largest tuna fishery, in the Western and Central Pacific, is in relatively good health, with the exception of one species (the bigeye).
The island states of the South Pacific have so far not played a major role in offshore fishery industries, even in their own EEZs, though a number of prospects for them to participate more actively have been identified (UNEP 1985). Some nations have already managed to generate revenue from the licence fees charged to foreign commercial fishing companies for fishing rights in their EEZs. However, implementation and management issues such as surveillance and enforcement capacities still need to be addressed. More importantly, the levels of harvest and ecologically-destructive fishing technologies need to be controlled to prevent depletion of fish stocks.
Aquaculture expansion over the past decade has affected many of the region's coastal areas through habitat conversion, introduction of exotic species, increased use of chemicals (pesticides, antibiotics and hormones), and in other ways. In 1992, the region provided 87 per cent of global aquaculture produce (FAO/RAPA 1994). As already mentioned, aquaculture has been a major cause of the destruction of more than 3 million ha of Southeast Asia's mangrove forests. In the Mekong basin, mangrove forests have also been degraded drastically, both in area and quality, particularly in the southern Mekong Delta. In Viet Nam, for example, mangrove forests shrank from 400 000 ha to 252 000 ha between 1950 and 1983 (MoSTE Viet Nam 1997). The once extensive mangrove forests along the coast of Thailand were reduced from nearly 368 000 ha in 1961 to 160 000 ha in 1996 (OEPP 1998). Substantial areas of mangroves have also been lost in South Asia and southern Japan (EA 1997). The widespread felling of mangroves has reduced coastal protection from cyclones and storm surges, increased seawater intrusion and acidified surface waters (Lean and others 1990). Indirectly, it has also affected commercial demersal fisheries that rely on mangroves as nursery areas.
The crown-of-thorns starfish has destroyed many reef habitats in the region and prevented reef recovery
Aquaculture production will become increasingly important since many marine fish stocks have reached their maximum exploitative level. However, in Southeast Asia, with the exception of Cambodia, where the cutting of mangroves for charcoal production and the conversion of forest to shrimp farms are recent and growing concerns (MRC/UNEP 1997b), the rate of mangrove forest depletion and coastal environmental degradation may slow down as a result of protective measures (ASEAN 1997).
Coral reefs have come under similar pressures (see map). In addition to mangroves, excessive land reclamation and coastal development have harmed extensive areas of coral reef in the south of Japan since 1972 when Okinawa returned to Japanese control. At the same time, the crown-of-thorns starfish has destroyed some 90 per cent of the reef habitat and prevented reef recovery (EA 1997, Mezaki 1988). In the Philippines, the combined effects of sediments, industrial and domestic pollutants, and destructive fishing techniques have damaged some 70 per cent of coral reefs. This has affected local self-sufficiency in many communities since Filipinos derive nearly half of their protein from fish (FAO 1993a). Reefs in the Mekong basin have been similarly affected. Australia has the largest area of coral reefs in the world and, by international standards, they are still in good condition. However, they are now exposed to significant pressures, with those close to population centres and tourism activities showing the most signs of damage. The Great Barrier Reef is the best-known example (see box).
Coastal and marine water pollution has increased throughout the region, mainly due to direct discharges from rivers, increased surface run-off and drainage from expanding port areas, oil spills and other contaminants from shipping, and domestic and industrial effluent. Offshore mineral exploration and production activities are further sources of pollutants.
Two-thirds of the world's total sediment transport to oceans occurs in Southeast Asia (GEMS 1996) - the combined result of active tectonics, heavy rainfall, steep slopes and erodible soils disturbed by unsound agricultural and logging practices. In Malaysia, the damage to fisheries from siltation alone exceeds the damage caused by bacterial contamination from sewage (FAO 1993b). In addition, Asian rivers are generally heavily contaminated with untreated sewage and industrial effluent.
Oil pollution is a significant problem along major shipping routes and an increasing number of accidents have occurred in recent years. The open ocean of the Sea of Japan/East Sea contains nearly twice as much oil as the surface of the Northwestern Pacific Ocean. Coastal installations are also a major source. In the port of Chittagong in Bangladesh, about 6 000 tonnes of crude oil are spilled a year and crude oil residue and wastewater effluent from land-based refineries amount to about 50 000 tonnes a year (Khan 1993).
One of the most serious issues is the decline in water quality caused by rising levels of nutrients from land-based sources. Expansion of intensive agricultural practices has resulted in increased agrochemical pollution, particularly in developing countries of the region. Fertilizer consumption rose by 340 per cent over the period 1975-95 and pesticide use has increased fourfold since 1977 (Holmgren 1994). Inorganic nitrogen and phosphorus are the major pollutants of China's near-shores seas. In South Asia, shellfish and finfish have been contaminated by increasing pesticide pollution. Australia's marine waters are generally low in nutrients and therefore productivity. However, rising levels of nutrients is considered to be one of the most serious marine issues. Each year, Australia's sewerage systems discharge about 10 000 tonnes of phosphorus and 100 000 tonnes of nitrogen, much of which enters the sea (Commonwealth of Australia 1996).
Red tides are caused by phytoplankton blooms which deplete oxygen in coastal waters, causing the mass death of aquatic organisms. In addition, the algae may produce toxins which cause shellfish poisoning and present a serious health hazard to consumers. Red tides have become a major concern in several countries, including Philippines (UNESCAP/ADB 1995), Australia (Hallengraeff 1995), New Zealand, Japan (OECD 1994), the Republic of Korea (Government of Republic of Korea 1998) and China (Zhang and Zou 1997) and seem to be increasing in frequency. The repeated blooms of toxic algae that have killed marine life and made hundreds of people ill are considered the most dramatic development in New Zealand's coastal waters since 1990 (Chang 1993, Robertson and Murdoch 1998).
It has been suggested that changes in sea surface conditions may have contributed to the spread of toxic algae and invasive seaweeds in New Zealand waters (Chang 1993, Hawes 1994). Average temperatures in the oceans around Australasia are generally rising and there is evidence that sea level in the sub-region has risen about 2 mm a year over the past 50 years (IPCC 1998). The potential impacts of climate change and sea-level rise are considered among the greatest environmental threats for the island states in the region and particularly for the atolls of the South Pacific. The predicted changes such as increased frequency and severity of tropical cyclones, coastal inundation and flooding as well as saltwater contamination of drinking water supplies could have profound consequences for agriculture, forestry, coastal development and human health (IPCC 1998).
By the year 2000, nearly half the world's coastal population (477.3 million people) is expected to be housed in urban conglomerations along Asian shores (WRI, UNEP and UNDP 1994). It is clear that the uncontrolled exploitation of the region's coastal resources requires a more effective management system, and that there is an urgent need to move from information gathering to concrete actions aimed at management and problem-solving.