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Marine and coastal pollution

Pollution has considerably degraded the coastal and marine environment, including estuaries, of the region over the past 30 years. Increased wastes from landbased urban, industrial and agricultural activities as well as from offshore oil and gas exploitation are discharged untreated in the coastal region (MoSTE Viet Nam 1999).

The most significant sources of pollution include oil from ships, sewage and other domestic wastes, and industrial effluents. The main route of marine transport of oil from the Gulf is across the Arabian Sea, and accidental oil spills have been frequently reported along oil transport routes, at points of discharge and loading of oil carriers. The shipping of oil coupled with increasing emphasis on offshore oil exploration makes the northern Indian Ocean extremely vulnerable to oil pollution. Oil spills also cause severe pollution in ports in Bangladesh, Indonesia, Malaysia and Pakistan (DoE Malaysia 1996, 1998). In addition, the cleaning of oil tanks in and around ports has led to the frequent formation of tar-balls on the southwestern beaches of Sri Lanka. In the PICs, marine pollution from ships is a threat that is likely to increase as trade and economies develop further.

The enhanced use of agrochemicals on land and discharge of chemicals into seawater is a common problem. An estimated 1 800 tonnes of pesticides enter the Bay of Bengal every year (Holmgrem 1994). In the Sea of Japan, a survey has revealed high concentrations of mercury, the source of which could have been wastewater from chemical plants (MSA 1997), while the Russian Federation admitted in 1993 that the former Soviet Union had dumped nuclear wastes there 'for decades' (Hayes and Zarsky 1993). In spite of international regulations, marine pollution in the Sea of Japan and the Yellow Sea has continued to worsen.

Tourism and other recreational activities also pose a threat to coastal ecosystems in many countries. The construction of tourism infrastructure has both a direct and indirect adverse impact on coastal environments through infilling, dredging and resuspension of contaminated silts, discharge of untreated or partially treated sewage, operational leaks, and discharge of hydrocarbons and waste dumping. Sand dunes, an important component of coastal ecosystems in the region, have also been eroded as a result of tourism activities.

Sediment load in the coastal zones of South Asia is high, mainly as a result of soil erosion caused by poor land-use practices and construction activities. Annually, about 1.6 billion tonnes of sediment reach the Indian Ocean from rivers flowing from the Indian sub-continent. The total sediment load of the river system of Bangladesh alone amounts to about 2.5 billion tonnes, of which the Brahmaputra carries 1.7 billion tonnes and the Ganges 0.8 billion tonnes (UNEP 1987). Coastal erosion is severe in many areas including the Andaman coast, the Gulf of Thailand, Japan and the PICs.

Managing ballast water discharges in Australia

The annual discharge of ballast water in Australian coastal waters is about 150 million tonnes from international vessels and 34 million tonnes from coastal vessels. A major incursion of black-striped mussels in Darwin Harbour in early 1999 prompted the establishment of a National Task Force on the Prevention and Management of Marine Pest Incursions. A major recommendation of the task force was the establishment of a single national management regime for vessels. Its recommendations are implemented through the National Introduced Marine Pests Coordination Group which was established under the Ministerial councils for environment, fisheries and aquaculture, and transport. The Consultative Committee on Introduced Marine Pest Emergencies, a mechanism for emergency responses to introduced marine pests, was introduced in 2000.

Since 1990 the Australian Quarantine and Inspection Service (AQIS) has adopted voluntary guidelines and measures to manage ballast water. In July 2001, Australia introduced mandatory ballast water management for international vessels entering its waters. Vessels are assessed by AQIS: high risk vessels are required to fully exchange ballast water at sea, while low risk vessels are allowed to exchange within coastal waters.

Source: Environment Australia 2001