a "knee-jerk reaction" and says, "sharks are top order predators that play an important role in the functioning of marine ecosystems. We need them for healthy oceans." Oil spills While there have been no oil spill environmental disasters of the scale of the Exxon Valdez in the country, Australia has a large oil industry and there have been several large oil spills . Spills remain a serious threat to the marine environment and Australian coastline. The largest spill to date was the Kirki tanker in 1991 which dropped 17,280 tonnes of oil off the coast of Western Australia. In March 2009, the 2009 southeast Queensland oil spill occurred, where 200,000 litres were spilled from the MV Pacific Adventurer spilling more than 250 tonnes of oil, 30 tonnes of fuel and other toxic chemicals on Brisbane's suburban beaches. Premier Anna Bligh described the spill as "worst environmental disaster Queensland has ever seen". Ocean dumping A serious issue to the Australian marine environment is the dumping of rubbish from ships. There have been a number of cases, particularly involving the navy of Australian and other countries polluting Australian waters including the dumping of chemical warfare agents. Recently documented cases include the aircraft carrier USS Ronald Reagan in 2006 which was found to be dumping rubbish off the shores of Moreton Island. In Victoria, a large number of toxic drums containing 1,2-Dichlorobenzene xylenol, a substance very toxic to aquatic creatures washed up on beaches during May 2009 presumably fallen off a passing container ship. Invasive species Australia's geographical isolation has resulted in the evolution of many delicate ecological relationships that are sensitive to foreign invaders and in many instances provided no natural predators for many of the species subsequently introduced. Introduced plants that have caused widespread problems are lantana and the prickly pear bush. The introduction and spread of animals such as the cane toad or rabbit can disrupt the existing balances between populations and develop into environmental problems. The introduction of cattle into Australia and to a lesser extent the dingo, are other examples of species that have changed the landscape. In some cases the introduction of new species can lead to plagues and the extinction of endemic species. The introduced species red fox has single-handedly caused the extinction of several species. Tasmania takes the threat of red fox introduction so seriously that it has a government sponsored taskforce to prevent fox