The North American signal crayfish, which had been introduced to English waters decades ago and spread steadily north, were taking over. 北美标志性的小龙虾是在数十年前被引入英国境内,并且向北蔓延最后占据了水域。
But in Scottish streams and lochs, these creatures are intruders. American crayfish may be destroying the catch. 然而在苏格兰,这种生物却是入侵者,美国小龙虾可能会毁掉苏格兰的生态。