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Sex. It drives people to do crazy things. Animals too. They'll make unsettling sounds, perform complex dances, or show off giant plumes of colorful feathers.
性会让人们做些疯狂的事情。动物也不例外。它们会发出让人心绪不宁的声音、表演复杂的舞蹈、或是炫耀绚丽多彩的羽毛。
And, famously, salmon will swim hundreds of kilometers upstream to get down to business. They also inadvertently rework the landscape.
而最著名的，就是鲑鱼会向上游游数百千米来解决性的问题。它们在无意中改变了生态景观。
"Adult salmon spend most of their life out in the ocean and then they come in to freshwater to mate." Washington State University ecologist Alex Fremier. "What the female salmon will do is, she digs a hole in the streambed."
华盛顿大学的生态学家阿莱克斯·弗莱米尔表示：“成年鲑鱼一生中大多数时间都在海里，但是当它们交配时要去淡水区。而雌性鲑鱼所需要做的就是在河床上挖一个洞。”
That little hole is called a redd. That's where the salmon lays her eggs. And Fremier says when she builds it, she basically "unpacks" the streambed, making all those loose sands and gravels more mobile.
挖的这个小洞被称为redd，就是鲑鱼产卵的地方。弗莱米尔称，当雌性鲑鱼建造好这个洞以后，她基本上就是将河床“解压”了，让松软的沙子和碎石更易流动。
High water and flooding events move that sediment, which in turn exposes bedrock to further erosion.
高水位以及汛期会使砂石等沉积物移动，这样反过来也会增加基岩的腐蚀程度。
"It's quite impressive. We did not expect to have salmon, in some cases, changing the vertical position of a river channel up to 30 percent more than it would have without salmon in it."
“这的确非常震撼。与没有鲑鱼的河道相比，我们没有想过鲑鱼会将河道的垂直距离改变30%左右。”
Fremier hypothesized that salmon not only influence landscape evolution, but that the evolution of salmon as a species itself has a landscape-level impact.
弗莱米尔假设，鲑鱼不仅可以影响景观演化，同时它们自身的进化也会影响自然景观。
To test the idea, he and colleagues recreated salmon redds in an experimental flume.
为了验证这一想法的正确性，弗莱米尔和同事们在实验水槽中制造了鲑鱼的“redd”。
Then they compared findings from the flume with real field observations. They cross-referenced all that data with discoveries from a study that modelled river profile erosion over five million years.
之后，他们将研究结果与实地观察结果进行比较，并将发现的所有数据和之前模拟的五百万年前的河流横断面的研究进行了对照。
"We were stunned by the fact that it actually had a larger scale effect, given that we account for tectonic uplift, the big floods, like a lot of flood water moving downstream, different conditions of the gravel sizes on the river. I think we were all surprised by the fact that salmon could have such a large effect at that million-year scale."
“随后我们被这样一个事实惊呆了，因为它实际上有一个更大规模的效应。因为我们还考虑到构造隆起、洪水等因素，比如大量洪水向下游移动、河流里不同尺寸条件下的碎石。我想我们都对鲑鱼能在这百万年里有如此巨大的影响感到惊讶。”
