Invasion of the Habitat Snatchers

Invasive species are wreaking havoc on African wetlands to the tune of billions of dollars per year, according to a new study by the World Conservation Union (IUCN). For example, the water hyacinth, introduced from the Amazon Basin as an ornamental plant, has spread to most of Africa's lakes and rivers, choking out other flora and fauna, making fishing impossible, and restricting water supplies. Similarly, the IUCN says, the nonnative Nile perch has driven more than 200 native fish to extinction. Meanwhile, across the world, the Union of Concerned Scientists says that 122 harmful invasive species -- some of them from Africa -- have set upon Texas, threatening native species and agricultural lands.