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SSS 2008-07-24

时间:2010-05-14 05:45来源:互联网 提供网友:木渐浅。   字体: [ ]
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This is Scientific American's 60-Second Science. I’m Karen Hopkin. It’ll just take a minute.

 

When you think about an ecosystem1, you usually think of the big animals that live there. The Serengeti’s ruled by lions. And estuaries2 are populated by fishes, birds, snails3 and maybe the occasional otter4. But there’s more to an ecosystem than meets the eye. Because a team of scientists from the US and Mexico has found that parasites5 constitute a sizeable chunk6 of the biomass of an ecosystem. The scientists catalogued and weighed all of the plants, animals and parasitic7 species living in three river estuaries. They found that in terms of sheer bulk, parasites represent about three percent of the biomass of these ecosystems8. Pound for pound, one parasite—the trematode fluke that infects a certain snail—outweighs all of the estuaries’ birds, which are the ecosystem’s top predators9. The results appear in the July 24 issue of Nature. That means that creatures you can’t see might be even more important to the health of an ecosystem, and to its balance of power, than the ones you can see. For example, in these estuaries, snails that are infected with trematodes outnumber those that are fluke-free. Now that’s what you call a controlling interest.

 

Thanks for the minute for Scientific American's 60-Second Science. I’m Karen Hopkin


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1 ecosystem Wq4xz     
n.生态系统
参考例句:
  • This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
  • We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。
2 estuaries 60f47b2d23159196be8449188dca90a4     
(江河入海的)河口,河口湾( estuary的名词复数 )
参考例句:
  • We also recognize the diversity and complexity of controlling in fluences in estuaries. 我们也认识到在河湾内控制影响的多样性和复杂性。
  • Estuaries also contribute to economy through tourism and fishing. 河口还为人类提供了休闲和教育的场所。
3 snails 23436a8a3f6bf9f3c4a9f6db000bb173     
n.蜗牛;迟钝的人;蜗牛( snail的名词复数 )
参考例句:
  • I think I'll try the snails for lunch—I'm feeling adventurous today. 我想我午餐要尝一下蜗牛——我今天很想冒险。 来自《简明英汉词典》
  • Most snails have shells on their backs. 大多数蜗牛背上有壳。 来自《简明英汉词典》
4 otter 7vgyH     
n.水獭
参考例句:
  • The economists say the competition otter to the brink of extinction.经济学家们说,竞争把海獭推到了灭绝的边缘。
  • She collared my black wool coat with otter pelts.她把我的黑呢上衣镶上了水獭领。
5 parasites a8076647ef34cfbbf9d3cb418df78a08     
寄生物( parasite的名词复数 ); 靠他人为生的人; 诸虫
参考例句:
  • These symptoms may be referable to virus infection rather than parasites. 这些症状也许是由病毒感染引起的,而与寄生虫无关。
  • Kangaroos harbor a vast range of parasites. 袋鼠身上有各种各样的寄生虫。
6 chunk Kqwzz     
n.厚片,大块,相当大的部分(数量)
参考例句:
  • They had to be careful of floating chunks of ice.他们必须当心大块浮冰。
  • The company owns a chunk of farmland near Gatwick Airport.该公司拥有盖特威克机场周边的大片农田。
7 parasitic 7Lbxx     
adj.寄生的
参考例句:
  • Will global warming mean the spread of tropical parasitic diseases?全球变暖是否意味着热带寄生虫病会蔓延呢?
  • By definition,this way of life is parasitic.从其含义来说,这是种寄生虫的生活方式。
8 ecosystems 94cb0e40a815bea1157ac8aab9a5380d     
n.生态系统( ecosystem的名词复数 )
参考例句:
  • There are highly sensitive and delicately balanced ecosystems in the forest. 森林里有高度敏感、灵敏平衡的各种生态系统。 来自《简明英汉词典》
  • Madagascar's ecosystems range from rainforest to semi-desert. 马达加斯加生态系统类型多样,从雨林到半荒漠等不一而足。 来自辞典例句
9 predators 48b965855934a5395e409c1112d94f63     
n.食肉动物( predator的名词复数 );奴役他人者(尤指在财务或性关系方面)
参考例句:
  • birds and their earthbound predators 鸟和地面上捕食它们的动物
  • The eyes of predators are highly sensitive to the slightest movement. 捕食性动物的眼睛能感觉到最细小的动静。 来自《简明英汉词典》
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