Collapse_ How Societies Choose to Fail or Succeed - Jared Diamond [254]
Several major projects in the past to modify unutilized Australian rivers have turned out to be costly failures. For instance, in the 1930s it was proposed to build several dozen dams along the Murray River in order to permit freight traffic by ship, and about half of those planned dams were built by the U.S. Army Corps of Engineers before the plan was abandoned. There is now no commercial freight traffic on the Murray River, but the dams did contribute to the already-mentioned collapse of the Murray Cod fishery. One of the most expensive failures was the Ord River Scheme, which involved damming a river in a remote and sparsely populated area of northwestern Australia in order to irrigate land for growing barley, corn, cotton, safflower, soybeans, and wheat. Eventually, only cotton among all those crops was grown on a small scale and failed after 10 years. Sugar and melons are now being produced there, but the value of their yield does not come close to matching the project’s great expense.
In addition to those problems of water quantity, accessibility, and use, there are also issues of water quality. Utilized rivers contain toxins, pesticides, or salts from upstream that reach urban drinking areas and agricultural irrigation areas downstream. Examples that I already mentioned are the salt and agricultural chemicals from the Murray River, which furnishes much of Adelaide’s drinking water, and the pesticides from New South Wales and Queensland cotton fields, which jeopardize the marketability of downstream attempts to grow chemical-free wheat and beef.
In part because Australia itself has fewer native animal species than the other continents, it has been especially vulnerable to exotic species from overseas becoming intentionally or accidentally established, and then depleting or exterminating populations of native animals and plants without evolved defenses against such alien species. Notorious examples that I already mentioned are rabbits, which consume about half of the pasturage that could otherwise be consumed by sheep and cattle; foxes, which have preyed on and exterminated many native mammal species; several thousand species of plant weeds, which have transformed habitats, crowded out native plants, degraded pasture quality, and occasionally poisoned livestock; and carp, which have damaged water quality in the Murray/Darling River.
A few other horror stories involving introduced pests deserve briefer mention. Domestic buffalo, camels, donkeys, goats, and horses that have gone feral trample, browse, and otherwise damage large areas of habitat. Hundreds of species of insect pests have established themselves more easily in Australia than in temperate-zone countries with cold winters. Among them, blowflies, mites, and ticks have been especially damaging to livestock and pastures, while caterpillars, fruit flies, and many others are damaging to crops. Cane Toads, introduced in 1935 to control two insect pests of sugarcane, failed to do that but did spread over an area of 100,000 square miles, assisted by the fact that they can live for up to 20 years and that females annually lay 30,000 eggs. The toads are poisonous, inedible to all native Australian animals, and rate as one of the worst mistakes ever committed in the name of pest control.
Finally, Australia’s isolation by the oceans, and hence its heavy reliance on ship transport from overseas, has resulted in many marine pests arriving in discharged ballast water and dry ballast of ships, on ship hulls, and in materials imported for aquaculture. Among those marine pests are comb jellies, crabs, toxic dinoflagellates, shellfish, worms, and a Japanese starfish that depleted the Spotted Handfish native only to southeastern