These tiny things form the base of the food chain and play an important role in the global carbon cycle.

这些微小的东西构成了食物链的基础，并在全球碳循环中发挥着重要作用。

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The ocean's planktons form the bottom of both the food chain and the bulk of the carbon-oxygen cycle for our planet.

海洋的浮游生物即构成了食物链底端，又是我们地球碳-氧循环的交换场。

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Competition among the species is a continuing cycle in the animal food chain.

在动物的食物链上，不同种群之间的竞争是一个永不停息的循环。

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The cycle goes on and the levels of toxicity increases until you get to the top of the food chain with pelagic fish such as swordfish that end up on our dinner plate.

CNN: STORY HIGHLIGHTS