纪录片《我们的地球》 第48期 淡水资源(05)（在线收听）

A grizzly bear. From famine to feast, he's spoilt for choice.

一只灰熊。它已经很久没有打牙祭了，早就盼着这个机会

This Canadian bear is very special.

这只加拿大熊很特别

He's learnt to dive for his dinner.

它学会了潜水捕猎

But catching salmon in deep water is not that easy, and the cubs have lots to learn.

但要想在深水中捕获鲑鱼可不太容易，熊崽们还要很多东西要学

The annual arrival of spawning salmon brings huge quantities of food into these high rivers that normally struggle to support much life.

鲑鱼每年都会到河里产卵，于是这些平常只能勉强维持众多动物生计的高山河流终于有了提供饕餮大餐的机会

Although relatively lifeless,

尽管高山河流的生物量相对较少，

the power of these upland rivers to shape the landscape is greater than any other stage in a river's life.

它们却有能力改变地形在河流扮演的角色中，这才是最主要的

Driven by gravity, they're the most erosive forces on the planet.

它们借助地心引力，成为地球上最大的侵蚀力量。