伴随着人们的经济活动和国际交往，一些物种由原生存地借助于人为作用或其他途径移居到另一个新的生存环境并在新的栖息地繁殖并建立稳定种群，这些物种被称为外来物种。
They might seem innocent and lovely in your (1)aquarium, but released into the wild, your plants and fish can knock aquatic ecosystems right out of balance. Today’s invasive species: the (2)water hyacinth. Native to the Amazon basin, but considered an ornamental aquarium plant, the water hyacinth was introduced to Florida in 1884. By the mid-1950s, water hyacinths were clogging Florida’s water ways and interfering with navigation, not to mention displacing the native species. Clean up took millions of dollars, and they’re still spreading on every continent except Antarctica. Guess how many of the species on the International Union for the Conservation of Nature’s list of the one-hundred worst (3)invasive species are the result of aquarium and ornamental releases? How many? A full third! You see, when it comes to aquarium animals and plants, we’re dealing with mature adults, and particularly hardy ones at that, since the weaker ones don’t survive transport. So whenever they’re released into the environment, either intentionally or accidentally, they’re better able to establish themselves. Despite all this, until recently researchers have largely ignored the role of pet fish and aquarium plants when studying the spread of exotic and invasive species. Finally, it’s time for some guidelines, especially ones that encourage the trade of less invasive and aggressive species, or the substitution of native and/or safer species that people could grow instead.
在你的水族箱里它们或许看起来很天真，很可爱。但是一旦被放生到野外，你的植物和鱼就会打破水生生态系统的平衡。 今天的入侵物种是：水葫芦。 水葫芦原产于亚马逊河流域，但作为一种观赏性水生植物，在1884年被引入佛罗里达州。到20世纪中期，水葫芦就造成了佛罗里达州水路的堵塞，干扰航运，更何况还取代了本地物种。尽管清理花费了数百万美元，但是它们仍然在除南极洲以外的各大洲蔓延。 你猜猜在国际自然保护联盟的最严重的100个入侵物种名单里，有多少是因为水族箱和观赏性放生造成的？ 有多少呢？ 整整三分之一！你知道的在选取水族馆动植物品种时，我们一般选用已长大成熟的动植物，尤其是易养活的那类，因为其他那些相对脆弱的动植物在运输的路途上无法存活下来。因此不论他们何时被放生到外界，故意的或是无意的，它们都能够很好的适应生存。 尽管如此，直到最近研究者们在研究外来入侵物种时都很大地忽略了宠物鱼和水生植物所扮演的角色。最后，是时候该制定一些指导方针了，特别是针对减少入侵和侵略物种交易的规定，或者取而代之种植一些本地的和更安全的物种。