考满分 toefl

1 .Listen to part of a lecture in a Marine Biology class.

听一段海洋生物学课程上的演讲

1 .We've been talking about the decline of coral reefs in tropical areas all over the world... um... how natural and man-made stresses are causing them to degrade, and in some cases, to die.

我们一直在讲世界各地热带地区珊瑚礁的减少，自然和认为的因素是如何使他们退化，一些情况下，死亡的。

1 .So now let's focus on a specific example of a natural predator that can cause a lot of damage to coral reefs - The Crown of Thorns, or Cot starfish.

好的，我们现在来关注一个具体的例子，一个危害珊瑚礁的自然捕食者，棘冠海星，或叫CoT海星。

2 .The Cot starfish is found on coral reefs in the tropical Pacific Ocean and it eats coral.

CoT海星生活在热带太平洋的珊瑚礁里，并且以珊瑚为食。

3 .Now, in small numbers, the starfish don't affect coral reefs dramatically.

少量的海星并不会严重影响珊瑚礁。

4 .But periodically the starfish population explodes.

但是海星的数量会周期性的激增。

5 .And when that happens, the reefs can become badly damaged or even destroyed, something we are trying very hard to prevent.

激增时，珊瑚礁就会被严重伤害甚至毁灭，这是我们非常努力去预防的。

6 .For example, during the 1960, there was an outbreak of Cot starfish in the Great Barrier Reef, off the east coast of Australia.

如，在20世纪60年代，在澳大利亚东海岸的大堡礁，又一次CoT海星的剧增。

7 .Luckily, the Cot starfish population gradually declined on its own and the reefs recovered.

幸运的事，海星的数量渐渐自然减少了，珊瑚礁也回复了。

1 .But we were left wondering - what cause the population to increase so suddenly?

但是我们仍然在思考到底时什么使得海星数量如此迅速的增加。

2 .Well, over the years, we've come up with a few hypotheses, all still hotly debated.

多年来我们有一些猜想，仍在激烈的讨论之中。

1 .One hypothesis is that it's a natural phenomenon, that the starfish naturally undergo population fluctuations following particularly good spawning years.

一个猜测说这是一种自然现象，海星在一些产卵很多的年份以后数量波动。

1 .There are also several hypotheses that suggest some sort of human activities are partly responsible, like fishing.

还有几个猜测说一些人为的活动也有一部分责任，比如捕鱼。

2 .There are fish and snails that eat starfish, particularly the giant triton snail, which is main predator of the starfish.

一些鱼和蜗牛以海星为食，特别是大海蜗，它是海星的主要捕食者。

3 .These fish and snails have themselves experienced a decline in population because of overfishing by humans.

因为过度捕捞，这些鱼和蜗牛的数量都下降了。

4 .So with a decline in starfish predators, the starfish population can increase.

所以当海星的天敌减少了，海星的数量增加了。

1 .Another hypothesized human-related cause is fertilizer runoff.

另一个猜测的认为愿意是化肥。

2 .People use fertilizer for their crops and plants and a lot of it eventually makes its way from land into the seas.

人们给农作物和植物施肥，而很多肥料最终流入大海。

3 .It's fertilizer, so it has a lot of nutrients.

肥富含很多营养物。

4 .These nutrients have an effect on the starfish, because they cause an increase in the growth of phytoplankton.

这些营养物能影响海星，因为营养激发浮游植物的生长。

5 .Phytoplankton are microscopic plants that grow in the ocean.

浮游植物是一种微小的海洋植物。

6 .Larval Cot starfish eat phytoplankton in their first month of life, so more fertilizer in the ocean means more phytoplankton, which means more starfish, bad for the reefs.

幼年的海星在生命的第一个月中以浮游植物为食，于是更多的化肥流入海洋意味着更多的浮游植物，也就意味着更多的海星。这对珊瑚礁是有害的。

1 .Now, the final hypothesis has to do with the storm events.

最后一个猜测是关于暴风雨的。

2 .If some reefs are destroyed by storms starfish populations that inhabited those reefs would have to condense and concentrate on the reefs that are left.

如果珊瑚礁在暴风雨被毁坏，那里生活的海星就需要以剩下的珊瑚礁为食。

3 .So this can cause a kind of mass feeding frenzy.

所以这可以造成大量海星疯狂抢食。

1 .So we have ideas, but no real answer.

我们只有一些猜想，并没有真正的答案。

2 .And because we aren't sure of the causes for starfish population increases, it's difficult to prevent them.

而且因为我们不知道海星数量增长的真正原因，所以很难去预防。

3 .I mean, some progress has been made.

我想说 ，还是有一些进步的。

4 .For example, new survey techniques have enabled us to detect population increases when the starfish are quite young, so we can be ready for them.

比如，新的探测技术使我们可以在海星幼年时发现他们数量的增加，所以我们可以准备好（迎接大量海星）。

5 .But meaningful progress requires much better evidence about the cause.

但是我们还需要理解海星增加的成因会有有意义的进步。

1 .On the bright side, in all the research being done on causes, we have discovered something related to how starfish populations might affect coral reef diversity.

好的一方面是，在这些研究海星增长的原因的是严重，我们发现了海星可能影响到珊瑚礁的多样性。

2 .We think that when reefs are damaged, after a few years, the fastest-growing corals repopulate the areas.

我们认为当珊瑚礁被损坏的几年后，长速快的珊瑚礁重新布满了这些地区。

3 .And these fast-growing species can grow over the slower-growing species of coral, denying them light and preventing them from recovery.

而且它们的生长压制了长速慢的珊瑚品种，比如减少阳光和防止它们恢复。

4 .However, the faster-growing coral species are the preferred food of Cot starfish.

然而，这些长速快的珊瑚是海星喜欢的食物。

5 .So when an outbreak of Cot starfish occurs, they thin out the fast growing coral and may give the slower ones a chance to reestablish.

因此当海星数量激增时，它们会吃掉很多长速快的珊瑚，并且给生长较慢的珊瑚一个重新开始的机会。

6 .So without the outbreak, the diversity of coral would be reduced.

所以，没有海星的激增珊瑚的多样性就会被减少。