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The Murray–Darling basin is a large geographical area in the interior of southeastern Australia. Its name is derived from its two major rivers, the Murray River and the Darling River. The basin, which drains around one-seventh of the Australian land mass,〔 is one of the most significant agricultural areas in Australia. It spans most of the states of New South Wales, Victoria, and the Australian Capital Territory, and parts of the states of Queensland (lower third) and South Australia (southeastern corner). The basin is in length, with the Murray River being long. Most of the basin is flat, low-lying and far inland, and receives little direct rainfall. The many rivers it contains tend to be long and slow-flowing, and carry a volume of water that is large only by Australian standards. ==Native fauna== The Murray–Darling basin is home to many native animal species. The true numbers may not be known, but a fairly confident estimate has been made of these animals and the current status of their population. Among the aboriginal fauna in the region, the study found that there were: * 80 species of mammals, with 62 extinct and 10 endangered * 55 species of frogs, with 18 endangered * 46 species of snakes, with five endangered * five species of tortoises, with none endangered * 34 species of fish, with up to half either threatened or of conservation significance Four varieties of carp were used to stock up fish dams. Since then they have made their way into the river systems, where they spread quite quickly. Human introduction, possibly by anglers using small carp illegally as live bait has also increased their distribution.〔(【引用サイトリンク】title=General information about carp - biology, ecology and impacts )〕 These fish are very mobile, as they can travel easily on flood waters and their eggs can be transported by birds. Carp are a problem because they feed by sucking gravel from the river bed and taking all the edible material off it, before returning the rest to the water. This stirs up all the sediment, reducing the quality of the water. When caught by fishermen, carp must be killed by law. A project for developing daughterless carp shows promise for eliminating carp from the river system. Cane toads have entered the upper reaches of the Darling Basin and there are several reports of individuals being found further down the system.〔Ayers, D., Mazzer, T.M. and Ellis, M.V. (2004). Herpetofauna of the Darling Basin. In: The Darling (Eds. R. Breckwoldt, R. Boden and J. Andrew) (Murray-Darling Basin Commission, Canberra).〕 Cane toads compete with native amphibians and are toxic to native carnivores. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Murray–Darling basin」の詳細全文を読む スポンサード リンク
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