为了帮助托福考生更好的备考托福听力，小马托福小编为考生整理了TPO31听力音频全面的学习材料，有需要的考生可以在线下载了，托福考试中的托福听力是很有难度的一个部分，要想获取高分，在平时备考的过程中需要多加练习。

　　Lecture 3 -Marine Biology (Coral Reefs & CoT starfish)

　　Narrator：Listen to part of a lecture in a Marine Biology class.

　　Professor

　　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.

　　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. The Cot starfish is found on coral reefs in the tropical Pacific Ocean and it eats coral. Now, in small numbers, the starfish don’t affect coral reefs dramatically. But periodically, starfish population explodes. And when that happens, the reefs can become badly damaged or even destroyed, something we are trying very hard to prevent. For example, during the 1960s, there was an outbreak of CoT starfish in the Great Barrier Reef, off the east coast of Australia. Luckily, the CoT starfish population gradually declined on its own and the reefs recovered.

　　But we were left wondering – what cause the population to increase so suddenly? Well, over the years, we’ve come up with a few hypotheses. All still hotly debated.

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

　　上述就是TPO31听力音频的相关介绍，希望对考生有所帮助。

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