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when we say they eat fish

它们以鲑鱼为大餐, we dont mean theyve developed a mouth full of pointy teeth 说它们‘吃’鱼,但实际上它们在食物链中处于相当高的位置,研究这些生态系统的科学家猜疑 the trees were eating the bears leftovers, But whichever one is in short supply in a given area is deemed the limiting nutrient. 但在特定区域内, theyre actually pretty high up the food chain. 最重要的是, If that sounds your cup of tea, And along the northwest coast of North America, interactive courses you can take with a Premium subscription. 会员订阅后, nitrogen-14 tends to be excreted more than nitrogen-15. 由于我们不完全相识的生物化学的特性,你就能看到年轮中的氮含量—— the researchers were able to show how important salmon are to the trees. 研究人员可以或许证明鲑鱼对树木的重要性,尽量你大概认为鲑鱼是并不是凶猛的捕食者,为漫长的冬季蛰伏做筹备。

But salmon have a weirdly high amount of nitrogen-15, Since fish carcasses have lots of nitrogen in them, Go to to learn how you can take your chemistry skills to the next level this year! 登录进修如何让你的化学常识在本年更上一层楼! Fish-eating trees sound like theyre straight out of science fiction. 吃鱼的树, well,它们的营养物质渗入泥土, when compared with land-dwelling species. 但和与陆地生物对比。

the trees eat salmon. 在北美西海岸的很多丛林里。

And overall,听起来像是科幻小说里的走出来的。

Now,鲑鱼中氮-15含量很是高,我再汇报各人一个好动静, Thanks to Brilliant for supporting this episode of SciShow. 感激Brilliant对本期节目标支持。

the first 200 people to sign up at will get 20% off the annual Premium subscription. 前200名注册的观众将得到年会员8折优惠, you could take their course on chemical reactions and learn about molecules and how they interact. 譬喻, Like any living thing,因此动物的职位越高。

And they can do that because bears that do have pointy teeth and sharp claws catch the fish for them! 它们可以这样做, thats something todays sponsor——can help with. 那么Brilliant.org可以辅佐你, Thats partly because most salmon spend nearly all of their adult life in the ocean, in their bodies. 它们饮食中的所需氮-15就越多——因此, So head over there, And if youre a human whos been inspired by this episode to dive deeper into biochemistry。

它们体内就越多, During and after years when more fish came upstream to spawn, And it turns out nitrogen atoms can have either seven or eight neutrons and remain stable— 功效证明氮原子可以有7到8其中子而且保持不变—— so nitrogen has what chemists call two stable isotopes. 所以化学家称氮有两个不变的同位素,他们需要留意所有氮气!并不是所有的氮都是一样的,, Starting in the late 1990s, research revealed that trees near salmon streams in Alaska have impressively high levels of nitrogen-15. 从20世纪90年月末开始,研究发明阿拉斯加鲑鱼溪流四周的树木含有大量的氮-15, This is an all you can eat buffet for bears that feast on the salmon to get ready for their long winter hibernation. But bears are messy eaters. 这些是熊的自助餐, But theyre a real thing—one that exists right here on Earth. 可是它们确实存在——就存在于地球,并不是指它们长出了满嘴尖牙 or razor-sharp claws to pluck a swimming salmon from the water. 或可以或许水中捕捞鲑鱼的尖利爪子。

但熊是邋遢的食客, the more nitrogen-15 they have in their diet — and therefore, trees that received nutrients from salmon grew 19% bigger than those that didnt! 总的来说,。

when we say they eat fish, And its just one of the fun, if youre a tree who wants to grow nice and tall。

Over 99% of the nitrogen on Earth is the lighter kind: nitrogen-14. 地球上高出99%的氮都是较轻的那一种:氮-14, But to prove it, For example,你可进修更多有趣的交互课程,氮-14比氮-15更容易被倾轧体外, On top of that, the trees grew bigger rings with more nitrogen. 当更多的鱼游到上游产卵时, What we mean is that the trees obtain a large portion of their nutrients from fish. 我们的意思是, check it out and see if its right for you. 各人可以去看看这些课程是否适合你。

So, on a single stream, plants need a bunch of different nutrients to grow. 和许多有生命的事物一样, not all nitrogen is the same. 但为了证实这一点, in two months, they needed to follow the nitrogen! See, the higher up animals are。

树木就会长出更大的带更多氮的年轮, And animals use each nitrogen isotope slightly differently. 动物对每种氮同位素的利用略有差异, And since this happens at every level of the food chain, they make a one-way trip from the ocean up into streams to lay their eggs. 鲑鱼筹备产卵时, 部门原因是因为大部门鲑鱼成年后险些都糊口在海洋里, though you may not think of salmon as fierce predators, 假如你受这一集开导,是因为熊有尖尖的牙齿和尖利的爪子为它们抓鱼! When salmon are ready to spawn。

它们就在河岸上和树上留下了高出5000公斤的鲑鱼碎屑! And those scraps have a lot of something trees need desperately: nitrogen. 这些碎屑中有许多树木急需的对象:氮。

植物发展需要大量差异的营养物质,限制营养素凡是是氮,不只如此, scientists studying these ecosystems suspected 因为鱼的尸体含有大量的氮, For example,这些树从鱼身上获取大量的营养,仅在一条小溪中,树木就开始“吃”熊的残食,你可以进修他们的化学回响课程, Because of quirks of biochemistry we dont fully understand, the limiting nutrient is often nitrogen. 而在北美的西北海岸, , In many forests on the west coast of North America,进修分子和它们的化学回响,树以鲑鱼为食。

Ive got some good news for you,它们会从海洋出发, 假如它们的课程适合你。

在两个月的时间里, So the obvious conclusion: they get a lot of their nutrients from salmon! That wasnt all. 所以结论很明明:它们从鲑鱼中获取了大量营养,任何一种短缺的营养物质都被认为是限制营养素, Some nitrogen atoms have more neutrons than others. 一些氮原子比其他原子有更多的中子, and it just so happens that the chemical and biological processes that occur in seawater make more nitrogen-15 available there than on land. 海水中产生的化学和生物进程刚好能比陆地上的发生更多的氮-15, 由于这产生在食物链的每一层, once the salmon decomposed and their nutrients sank into the soil. 一旦鲑鱼腐朽, By looking at nitrogen in individual tree rings—those yearly layers you can see if you cut a tree in half — 通过调查单个树木年轮中的氮含量——假如你把一棵树砍成两半,从鲑鱼中得到营养的树木比那些没有从鲑鱼中得到营养的树木大19%,你最好不要错过这些寿司, And they show just how interconnected life on this planet is. 它们展示了这个星球上的生命是如何彼此接洽的。

youd better not skip out on the sushi. 假如你是一棵想长得又美又大的树, they left over 5000 kg of salmon scraps along the river banks and up into the trees! 譬喻,想深入研究生物化学,一路游到溪流产卵。