水域生态学教材外来种和生物入侵.pptVIP

外来种 ;美国, 自哥伦布踏上美洲大陆，估计有超过 30,000 中非本土物种被引进 (Pimentel et al., 2000)， 超过 4500 外来种在美国成功定居 2000 多种植物 2000 多种昆虫 239 植物病原 142 陆生脊椎动物 91 淡水贝类 70 种鱼类 (Office of Technology Assessment, 1993). 一些外来种已造成严重的经济损失和环境危害，而大多数其影响尚不清楚;将外来种引入水体生态系统中的原因;有关引进外来种术语的定义;;入侵种 Invasive species;水生态系统中的入侵种－水葫芦;水生态系统中的入侵种－ 杀手藻;Zebra mussel, Dreissena polymorpha ;Zebra mussel, Dreissena polymorpha, a small (2-2.5 cm) strikingly coloured animal;Hazard and damage: shuting down electrical utilities by clogging water intake pipes, causing $5 billion in damages by the year 2002 causing large-scale ecosystem changes and hastening the decline of our native freshwater mussels (50% decline in species in a decade) They gorge on phytoplankton, outcompeting zooplankton for this essential food and disrupting natural food webs. They adhere to the shells of our freshwater mussels-sometimes in numbers exceeding 10,000 zebra mussels to a single native mussel Native mollusk populations tend to crash within four years of zebra mussel colonization ;Impact of zebra mussel on aquatic ecosystem;Crayfish covered with Zebra mussel;It has caused major changes in water chemistry and increased transparency. In the western basin of Lake Erie, It has reduced phytoplankton crop by 80% and doubled the transparency. These might seem desirable consequences, but, in switching the predominant energy flows in this part of the lake to the benthos instead of the plankton, it may disturb the recruitment of fish dependent on the plankton Two species of goby(鰕虎鱼 ) from the Caspian Sea have been introduced to feed on the mussels. But may itself cause further biological problems if it is widely distributed.;Beach covered with zebra mussels;七鳃鳗 Sea Lamprey;Sea lamprey;尼罗尖吻鲈引入维多利亚湖;Simplified version of original food web in Lake Victoria;Influence of an exotic predator, Nile perch, on the food web of Lake Victoria (data from Ligtvoet and Witte, 1991);Lates niloticus;The flesh of Nile perch is not particularly liked by the local people.