The Coastal and Marine Environment
IntroductionAustralian waters span almost 60 degrees of latitude from Torres Strait to Antarctica, and 72 degrees of longitude from Norfolk Island to the Cocos Islands (OHT 4). They include a great range of geographic, geological and oceanographic features. Australia's marine environment extends from the shores and wetlands along the coastline to the ocean depths, and from tropical coral reefs to antarctic packice. Coastal and marine environments are under increasing pressure from human activities in the marine, coastal and terrestrial environments (OHT 5).
The Coastal Zone
The coastal zone comprises components of land (catchments, wetlands, dune systems) and the sea (intertidal and subtidal regions of the continental shelf) (see Figure 1, OHT 6). Biologically, the coastal zone extends to the edge of the continental shelf. Legally, there are prescribed limits of responsibility determined by the Commonwealth and State authorities. Under international law, Australia is entitled to a 12 nautical mile territorial sea. Beyond territorial waters is the Australian Fishing Zone extending 200 nautical miles seaward and encompassing an area of about 3 million square kilometres. Because each State and Territory has title to the seabed of the territorial sea adjacent to it,
Australia's coastal zone lacks a unified definition and some sections are subject to many legislative instruments and regulations (OHT 7). For the purpose of the actions of the Commonwealth, the boundaries of the coastal zone are considered to extend as far inland and as far seaward as necessary to achieve its coastal policy objectives, with a primary focus on the land-sea interface. Thus any discussion of coastal matters must focus on the shoreline, coastal waters and islands, estuaries and other tidal waters, coastal wetlands and land adjacent to these features. Australia's coastal zone supports most of the nation's population and much of its economic and social activity. Therefore, sound management of the coastal zone is of profound importance to the maintenance of many of Australia's important ecological systems as well as to the socio-economic development of the nation. The challenge is to manage the use of the coast in such a way that undesirable impacts are eliminated, or, at least, minimised.
Coastal and Marine Ecosystems
Estuaries are meeting places of fresh and salt waters. They are naturally rich in nutrients, ecologically highly productive and important fish habitats. Australian estuaries have been the focus of urban and industrial development and are important for recreation. Australia has 783 major estuaries. Clearing of river catchments in eastern and southern Australia has resulted in land erosion, sedimentation of rivers and increased sediment and nutrient levels in estuaries and adjacent coastal waters. Sedimentation is a major problem in ports and shipping channels. The flows of many of Australia's rivers have been significantly altered by dams, barriers, land reclamation schemes and flood mitigation schemes. These changes affect the hydrodynamics and flushing characteristics of estuaries. Of estuaries that have been studied, 64% in New South Wales and 22% in Victoria are considered to have poor water quality.
Coastal and Marine Studies
Many factors influence people's values (family, friends, media and personal experience) but it is education at schools, colleges and universities that gives people most of the formal knowledge and skills to make informed decisions and the ability to act on them. During their formal education every Australian student learns something about the sea in a variety of subjects from art to zoology.
The sustainability of coastal and marine systems also depends on Australians knowing about the marine environment, recognising the threats to it, wanting to care for it, and learning the skills to look after it. Therefore, coastal and marine studies are also vital for achieving the environmental awareness, values attitudes, and skills consistent with ecologically sustainable development. To this end, a long-term national coastal and marine education programme has been introduced to help develop: