Ballast water is typically taken from estuarine or sheltered waters along with associated fauna and flora and then discharged on reaching the destination port. Individuals, larvae or cysts may survive the journey and establish in the new port. A recent desktop study by the Australian Museum (1997) reviewed the physical and biological characteristics of ballast water in relation to some widespread introduced species in Australia. They concluded that several of these species could have been transported as larvae in the ballast water tanks as the voyage was sufficiently short to allow the larvae to survive. Similarly, Carlton and Geller (1993) analysed ballast water from cargo ships in Oregon to determine the presence and abundance of non-indigenous organisms. The diversity of taxa present, especially as inconspicuous life-stages, suggested that invasions already were pervasive.

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Department of Environment and Heritage