The Peel-Harvey estuarine system, Western Australia
McComb, A.J. and Lukatelich, R.J. (1995) The Peel-Harvey estuarine system, Western Australia. In: McComb, A.J., (ed.) Eutrophic shallow estuaries and lagoons. CRC Press, Boca Raton, USA, pp. 5-17.
Peel Inlet and Harvey Estuary are two adjoining estuarine basins in southwestern Australia, which in recent years have become highly eutrophic. One of the basins, Peel Inlet, supports a large biomass of green macroalgae; while the other, Harvey Estuary, has dense summer blooms of the blue-green alga (Cyanobacterium) Nodularia spumigena Mert.
This estuarine system is fed by three rivers, and communicates with the Indian Ocean through a common inlet channel (Figure 1 ). Beside the inlet channel lies the city of Mandurah (population 30,000), which is within 70 km of the capital city of the state, Perth, and its port of Fremantle. Once a quiet weekend retreat and a place for retirement, the Mandurah area has become rapidly urbanized because of the increasing population of the state and the construction of good access roads to Perth. Canal estates have been established at several points along the shores, especially near the inlet channel and along the Murray River. Depending on the seasons the shallow basins are used for sailing, water-skiing, windsurfing, fishing, crabbing and prawning; for example during a 5-day survey in January 1978, 1314 boats were found to be engaged in crabbing, 427 in fishing, 344 in sightseeing, 76 in water skiing, and 71 in 'miscellaneous activities' . 1 There is a commercial fishery (usually some $A2M per annum) which, although small in relation to marine fisheries of the western coast, is nevertheless one of the largest, estuarine-based fisheries in Australia.
The estuaries lie on a sandy coastal plain of low relief, drained for agriculture since the 1920s. The coastal plain is separated from uplands in the catchment by a major fault line, the Darling Escarpment, which runs north-south for approximately 300 km, and is some 300 m tall (Figure 2). The escarpment marks an abrupt change in land use from agriculture on the plain to forested catchment on the immediate uplands; much of the water supply for urban areas is from reservoirs located along the escarpment. Further inland rainfall is reduced, and forested country gives way to land which has been cleared for grazing and wheat farming.
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