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Compiled by Leon P. Zann
Great Barrier Reef Marine Park Authority, Townsville Queensland
Department of the Environment, Sport and Territories, Canberra (1995)
ISBN 0 642 17391 5
Ports, shipping and offshore petroleum industries may affect the marine environment through water pollution, particularly by hydrocarbons, and loss of habitat.
Australia is an isolated island continent with a long coastline and shipping is a major economic use of our seas, estuaries and coastlines. In terms of tonnage carried and distance travelled, Australia ranks as the fifth largest user of shipping in the world. Each year there are around 12,000 overseas shipping arrivals and almost 380 million tonnes of freight carried in Australian waters.(36)
Figure 74: Major ports around Australia.The number of ship visits to the ports (1992) are indicated. Petroleum tanker routes (arrows, showing the number of visits to each region)(1988) are also indicated.
Shipping and port operations produce a variety of environmental impacts such as pollution from oil, hazardous cargoes, tributyl tin from antifouling paints, litter and sewage; and introductions of exotic or foreign organisms in ships' ballast waters or attached to ships' hulls(36). These are specifically examined in the next chapter.
Australia has 68 main ports. The impacts of ports include loss of habitat from reclamation and dredging; physical alteration of coastal environments; increased sediment from dredging; and pollution by oil, toxic chemicals, litter and antifouling paints. While ports are amongst the most disturbed marine environments in Australia, technical, engineering and management solutions do exist to prevent or minimise many of their environmental impacts (39).
The general effects of oil spills on the marine environment are well known through a long list of eco disasters such as the Exxon Valdez in Alaska. So far Australia has been fortunate in that there have been only two large spills (over 1,000 tonnes), the Oceanic Grandeur in Torres Strait and the Kirki off Western Australia, but neither of these appeared to result in major environmental damage.(39)
The international nature of the shipping industry and its economic and strategic importance pose particular problems for the management of its environmental impacts. Australia has therefore adopted a number of international conventions covering marine pollution, for example the International Convention for the Prevention of Pollution from Ships (MARPOL), which deals with carriage and discharges of oil, noxious liquids, packaged harmful substances, sewage and garbage(39).
There have been several moderate but relatively destructive spills since 1991(39):
The risk of a major spill from shipping around Australia is considered to be high. The Bureau of Transport and Communications Economics estimated in 1991 that the risk of a major spill from shipping was 49% in any five year period, and 84% in any 20 year period.(39),(100)
The Australian Maritime Safety Authority (AMSA) has the national responsibility for maritime oil spill issues. Because it has never been possible to control a major spill, the prevention of spills through safe operations and navigation of ships is the primary objective of management. For example, since the MARPOL Convention took effect, discharges from ships have been reduced by about 60% worldwide. Navigation technology has also greatly improved and the use of global satellite positioning systems has greatly reduced the risk of accidents. Tankers built after 1993 have double hulls for added protection against holing.(39)
Australia has been a leader in the control of pollution from shipping. For example, in 1990 the hazardous Great Barrier Reef passage was the first area in the world designated as a 'Particularly Sensitive Area' by the International Maritime Organisation. All ships using the passage which are over 70 metres in length, and all ships carrying oil or toxic cargoes must now carry Australian registered pilots.(39),(69)
Despite best practice, oil spills are inevitable. Australia has a National Plan to Combat Pollution of the Sea by Oil which is managed by AMSA. This involves Commonwealth, State and Territory Governments, and the shipping, oil and exploration industries in order to maximise Australia's oil spill response capability. Pollution response equipment is stockpiled at strategic ports and oil terminals with a major industry stockpile in Geelong (Vic). The stockpile has the capability of controlling an oil spill of up to 10,000 tonnes. If necessary, additional equipment may be called upon from international stockpiles in Singapore and the United Kingdom. However, it is recognised that technology does not currently exist to prevent weather driven oil slicks from washing ashore or guarantee prevention of environmental damage and economic loss, except in favourable conditions.(39),(84)
Offshore petroleum production is of great economic and strategic importance to Australia. Some 72% of our liquid fuels and natural gas comes from offshore wells in Bass Strait, the Timor Sea and the North West Shelf. Current production of oil is over 3.5 million barrels per year(37),(84).
Over the past 30 years more than 1,100 wells have been drilled offshore and around 2,800 million barrels of oil have been extracted. The Australian offshore petroleum industry has a very good environmental record and only about 800 barrels of oil have been spilt since drilling began.(37),(84)
Potential environmental impacts of offshore petroleum exploration and production include effects of seismic surveys on marine organisms that are within several metres of the trailing cables, and effects on the communications and behaviour of marine mammals over a wider area; the construction of platforms and laying of pipes, which affect the sea floor in the immediate vicinity; disposal of 'produced water', which is present with the oil and contains traces of hydrocarbons; contamination by drill fluids that are used to lubricate the drill bit, and which contain various chemicals; and effects of increased shipping activity.(37)
A scientific review of the environmental implications of the offshore petroleum industry by the Australian Petroleum Exploration Association (APEA) in 1993 found that the risk of oil spills by Australian explorers was minimal, and that environmental effects have been minimal. It considered that Australian producers are world leaders in 'produced water' treatment standards and technology.(37)
A statistical risk study by the Bureau of Transport and Communications Economics estimated that the theoretical probability of a major spill (that is, greater than 1,000 tonnes) from offshore petroleum sources was around 26% in any five year period, and the risk of a pipeline spill was around 17% for the same period. However, the industry strongly argues that these are highly pessimistic estimates as they are based on overseas data, and that offshore oil technology has greatly improved in recent years.(38)
Despite the clean environmental record of the Australian offshore petroleum industry, many conservationists still perceive the industry as a major threat because of overseas disasters such as the Ixtoc 1 exploration well blow-out in the Gulf of Mexico. The offshore industry is, in turn, critical of the 'emotive' rather than scientific arguments of many conservationists and environmental managers.(38)
Oil drilling is prohibited in marine protected areas such as the Great Barrier Reef World Heritage Area and in Ningaloo Marine Park. In the Australian Antarctic Territory, any activity relating to mineral resources, other than scientific research, is prohibited. It is possible that the establishment of marine protected areas may affect oil exploration in those areas, and conversely, the issuing of offshore exploration leases may affect the future establishment of marine protected areas in lease areas.(38)
Major uses of the marine environment and their effects