Governments, private groups and individuals spend billions of dollars a year trying to root out non-native organisms that are considered dangerous to ecosystems, and to prevent the introduction of new intruders.
政府、私人团体以及个人每年都花费了大量的金钱来清除那些被认为会危害当地生态系统的外来生物,以及预防新入侵者的引入。