Southwest Australian Shelf large marine ecosystem
The Southwest Australia Large Marine Ecosystem (LME) is characterized by its temperate climate. The LME extends from the estuary of the Murray-Darling river to Australia’s southwest edge at Cape Leeuwin. The LME has a narrow shelf. It borders the Southern Ocean and includes the Great Australian Bight. Western boundary currents flow into the West Wind Drift, which circulates around the continent of Antarctica. It is bordered by the states of South Australia and Western Australia.
The Southwest Australian Shelf LME is considered a Class II, moderately high (150-300 grams of carbon per square meter per year) productivity ecosystem based on SeaWiFS global primary productivity estimates. This LME has small latitudinal range. It borders on the Southern Ocean and is a haven to thousands of fish and marine species including humpback whales, sea lions, penguins and dolphins. Locally significant upwelling of nutrient-enriched waters is known to occur at sites along the coast of South Australia. Zonation in this LME is evidenced by shallow-water reef fish. Three ecological barriers appear to inhibit dispersal: a sharp temperature gradient around Albany near the cessation of the Leeuwin Current; and two interruptions in the nearshore rocky reef area: in the center of the Great Australian Bight, and at the mouth of the Murray River. For a general understanding of oceanographic processes affecting nutrient dynamics and the productivity of Australian marine ecosystems, see the State of the Environment Report. For more information on productivity, see Furnas.
Fish and Fisheries
Australian waters are relatively nutrient-poor and unable to sustain large fish populations. This LME has a narrow continental shelf. Production is limited by low levels of nutrient-rich upwellings. Fish stocks in the Southwest Australia LME are quite small. Many species are endemic to Australia. Until recently, fisheries resources were usually managed in separate fishery units. Under the Environment Protection and Biodiversity Conservation Act 1999 (the EPBC Act), the Commonwealth Government has a framework that helps it to respond effectively to current and emerging environmental problems, and to ensure that any harvesting of marine species is managed for ecological sustainability. The Food and Agriculture Organization (FAO) provides information on Australia’s fisheries and the characteristics of the industry. The University of British Columbia Fisheries Center has detailed fish catch statistics for this LME. Click on the graph below for more information.
Pollution and Ecosystem Health
The LME is threatened by an increase in shipping. Ships empty of cargo that enter ports such as Adelaide are ballasted with water collected in the last port of call. This ballast water has been shown to contain organisms including bacteria, viruses, algal cells, plankton, and the larval forms of many invertebrates and fish. One issue in this LME is ocean dumping. There are also environmental impacts caused by tourism, and by the provision of infrastructure to support tourism (airports, power generation facilities, accommodation, sewage treatment and disposal facilities, moorings, and marine transport). For more information on pollution and ecosystem health, see Pogonoski, 2002, marine disturbances, coastal pollution, and the State of the Environment Report.
Thousands are involved in the fisheries, aquaculture and processing sectors of the economy. The FAO provides information on the characteristics and socioeconomic benefits of Australia’s fishing industry. Industry, shipping and tourism are major economic activities. Adelaide is this LME’s major city and shipping port. Marine and coastal-based tourism is important both in terms of domestic and international tourism. A significant proportion of the Australian population is involved in recreational fishing, diving, snorkeling, and boating. Tourists from overseas prize the natural and unspoiled marine environment. There are, however, social, cultural, economic and environmental impacts caused by tourism. Tourism may affect the lifestyle of residents in ways they perceive as intrusive. Negative social impacts may include real or perceived increases in crowding, prices, or crime, as well as increase conflict between commercial, recreational and indigenous interests.
The LME is bordered by the states of South Australia and Western Australia. One governance issue pertains to fisheries management. Australian fisheries resources are managed under both Commonwealth and State/Territory legislation. The demarcation of jurisdiction and responsibilities among these various governments has been agreed to under the Offshore Constitutional Settlement (OCS). Under OCS, the states and territories have jurisdiction over localized, inshore fisheries. The Commonwealth has jurisdiction over offshore fisheries, transboundary fisheries (extending to waters adjacent to more than one state or territory) and foreign fisheries. Each government has separate fisheries legislation and differing objectives. An important goal is to ensure that the exploitation of fisheries resources is conducted in a manner consistent with the principles of ecologically sustainable development. This includes the need to assess the impact of fishing activities on non-target species and the long-term sustainability of the marine environment. For more information on the governance of Australia’s fisheries, see the FAO web site. The marine tourism industry has produced a code of conduct that covers issues such as anchoring, removal of rubbish, fish feeding and preservation of world heritage values. Australia declared a 200 nautical-mile Exclusive Economic Zone in 1978. Australia is party to the following international agreements: Antarctic-Environmental Protocol, Antarctic Treaty, Biodiversity, Climate Change, Endangered Species, Environmental Modification, Hazardous Wastes, Law of the Sea, Marine Dumping, Marine Life Conservation, Nuclear Test Ban, Ozone Layer Protection, Ship Pollution, Tropical Timber 83, Wetlands, and Whaling.
Articles and LME Volumes
- Menon, H.B., 1998. Role of Oceanic fronts in promoting productivity in the Southern Indian Ocean. In: Kenneth Sherman, E. Okemwa and M. Ntiba. (eds.), Large Marine Ecosystems of the Indian Ocean: Assessment, Sustainability, and Management (Cambridge, MA: Blackwell Science) pp. 175-191. ISBN: 0632043180.
- Edwards, RJ, and WJ Emery, 1982. Australasian Southern Ocean frontal structure during summer 1976-77. Aust J Mar Freshwat Res 1982;33:3-22.
- Emery, WJ, 1977. Antarctic Polar frontal zone from Australia to Drake Passage. J Phys Oceanogr 7:811-822.
- Furnas, Miles J., Land-sea interactions and oceanographic processes affecting the nutrient dynamics and productivity of Australian marine ecosystems.
- Hart, T.J., 1942. Phytoplankton productivity in Antarctic surface water. Discovery Rep 21:261-356.
- Lutjeharms, J.R.E., and D.J. Baker, 1980. A statistical analysis of the mesoscale dynamics of the Southern Ocean. Deep sea Res 1980, 27:145-159.
- Pogonoski, J.J., D.A.Pollard and J.R.Paxton, 2002. Conservation Overview and Action Plan for Australian Threatened and Potentially Threatened Marine and Estuarine Fishes. Environment Australia.
- State of the Environment Report.
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