Continental seas of western Indonesia
Edinger, E.; Browne, D.R. (2000). Continental seas of western Indonesia, in: Sheppard, C.R.C. (Ed.) Seas at the millennium: an environmental evaluation: 2. Regional chapters: The Indian Ocean to The Pacific. pp. 381-404
In: Sheppard, C.R.C. (Ed.) (2000). Seas at the millennium: an environmental evaluation: 2. Regional chapters: The Indian Ocean to The Pacific. Pergamon: Amsterdam. ISBN 0-08-043207-7. XXI, 920 pp., more
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Document type: Review
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| Abstract |
The continental seas of western Indonesia cover the Indonesian areas of the Sunda Shelf, and include the Java Sea and the southern portion of the South China Sea. Adjacent areas covered in this chapter include the west coast of Sumatra, the Rores Sea, and the western edges of the Makassar Strait. This region is surrounded by Java and Bali to the south, Sumatra to the west, and Indonesian Borneo to the north, and covers approximately 1 million km². The waters of the Sunda shelf are less than 100 m deep throughout, and most of the region is microtidal. The mountainous islands surrounding the Sunda shelf are home to approximately 150 million people. The monsoonal climate with high rainfall and runoff leads to high rates of terrigenous sedimentation. The Sunda shelf is dominated by fine siliciclastic sediments, except around coral reefs or straits with strong currents. Most coastlines are prograding rapidly, with localized cases of coastal erosion related to human activities. The marine biodiversity of western Indonesia is high, because of its proximity to the Southeast Asian biodiversity centre in eastern Indonesia and New Guinea. The dominant nearshore habitats are mangroves, seagrass beds, and coral reefs, all of which are threatened by land-based pollution and marine resource extraction. Of the 2.1 million ha of mangrove area present in western Indonesia in 1980, nearly 60% have since been destroyed for timber, plantations, or shrimp ponds. Similarly, about 50,000 km² of coral reefs occur in western and central Indonesia, but half of these are in poor condition. Major environmental threats to the seas of western Indonesia stem from rural, industrial and domestic land-based pollution, and from a variety of marine resource extraction activities. Agricultural runoff, deforestation, and mining shed nutrients and sediments into nearshore waters. Likewise, untreated sewage and poorly controlled industrial effluents are discharged into rivers, and thence into nearshore marine environments. Landfill and over-extraction of groundwater lead to ground subsidence and flooding in coastal districts of major cities, causing a variety of health problems. Marine debris from both urban and rural sources causes a serious litter problem on many beaches in western Indonesia. The effects of land-based pollution on coral reefs are most severely demonstrated on the reefs of Jakarta Bay and the Thousand Islands. Marine resource extraction activities with major effects in western Indonesia include oil production, shipping and refining, capture fisheries, aquaculture, and coral mining. Western Indonesia produces vast amounts of oil and natural gas, and major petroleum shipping lanes run through the Strait of Malacca, South China Sea, Makassar and Lombok Straits. The major shallow water habitats of western Indonesia-mangroves, seagrass beds, and coral reefs-are all highly sensitive to oil pollution. Capture fisheries for both pelagic and demersal fish are severely overexploited throughout western Indonesia, despite two decades of warnings and the 1980 ban on trawlers in most of Indonesia. Fisheries' decline is further exacerbated by mangrove clearing, and by destructive fishing practices including blasting and cyanide fishing. Aquaculture has grown explosively in western Indonesia, and releases large fluxes of nutrients, organic detritus, antibiotics and other chemicals, and sediment into nearshore waters. Shrimp farms are the primary cause of mangrove destruction, contributing to coastal erosion. Coral mining for building stone remains a threat to coral reefs. Protective efforts include several large government projects, endangered species legislation, and a slowly growing system of marine protected areas. The Clean Rivers program (PROKASIH) has reduced discharge of industrial pollutants into nearshore waters, but is limited to major industries, ignoring pollution from small industries and domestic sources. Endangered species legislation nominally protects giant clams, marine turtles, dugongs, and other species, but implementation and enforcement are insufficient. Indonesia has established a system of Marine Protected Areas (MPAs), with 1.1 million ha of MPAs in western Indonesia. Indonesia remains far behind its target of 30 million ha of MPAs by the year 2000. Furthermore, most MPAs do not have management plans; existing management efforts suffer from poor implementation. The recent economic and political turmoil in Indonesia bodes ill for marine environmental conditions in western Indonesia, as rapid economic return takes priority over environmental protection and conservation. |
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