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会“吃”鲑鱼的树 – 译学馆
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会“吃”鲑鱼的树

These Trees Eat Salmon!

Thanks to Brilliant for supporting this episode of SciShow.
感谢Brilliant支持本期《科学秀》节目
Go to Brilliant.org/SciShow
赶快登录Brilliant.org/SciShow网站
to learn how you can take your chemistry skills to the next level this year!
学习如何在今年让你的化学成绩得到提高
《科学秀:微真相》
Now fish-eating trees sound like
“会吃鱼的树”听起来像
they’re straight out of science fiction.
科幻小说里描写的那样神奇
But they’re a real thing—one that exists right here on Earth.
但这种树在地球上还真的存在
In many forests on the west coast of North America,
它们生长在北美西海岸的大片森林中
the trees eat salmon.
以鲑鱼为养料 维系生存
And they show just how interconnected life on this planet is.
它们证明了地球上的生物是如此的紧密相连
Now, when we say they “eat” fish,
我们在这里所谓的“吃”鱼
we don’t mean they’ve developed a mouth full of pointy teeth or razor-sharp claws to
并不是说它们用尖牙利爪
pluck a swimming salmon from the water.
从水里抓活的鲑鱼吃
What we mean is that the trees obtain
我们说的是 这些树从鱼类中
a large portion of their nutrients from fish.
汲取大部分的营养
And they can do that because
它们之所以能够这样存活
bears that do have pointy teeth and sharp claws catch the fish for them!
是因为有熊用尖牙利爪为它们捕鱼
When salmon are ready to spawn,
每到产卵季节 鲑鱼就会
they make a one-way trip from the ocean up into streams to lay their eggs.
“义无反顾”的从海洋游到河里产卵
This is an all you can eat buffet for bears that
这是为熊准备的自助大餐
feast on the salmon to get ready for their long winter hibernation.
它们享受鲑鱼盛宴 为漫长的冬眠做准备
But bears are messy eaters.
但熊吃起东西来弄得一片狼藉
For example, in two months, on a single stream,
比如 两个月的时间内 熊会在小溪两岸
they left over 5000 kg of salmon scraps along the river banks and into the trees!
留下5000多公斤渗入树根的鲑鱼渣滓
And those scraps have a lot of something trees need desperately: nitrogen.
这些渣滓含有许多树木急需的营养物质:氮
Like any living thing,
植物和其它生物一样
plants need a bunch of different nutrients to grow.
也需要大量不同的营养物质
But whichever one is in short supply in a given area
限制性营养指的是任意一种
is deemed the limiting nutrient.
营养物质在某个区域供给短缺
And along the northwest coast of North America,
通常在北美的西北海岸
the limiting nutrient is often nitrogen.
限制性营养就是氮
Since fish carcasses have lots of nitrogen in them,
因为鱼类尸体氮含量很高
scientists studying these ecosystems suspected
所以一些研究这些生态系统的科学家推测
the trees were “eating” the bears’ leftovers,
如果鲑鱼腐烂分解
once the salmon decomposed
这些营养物质会渗入土壤里
and their nutrients sank into the soil.
这些树木就可以“吃掉”熊留下的残羹剩饭
But to prove it, they needed to follow the nitrogen!
但为了证实这种观点 科学家们需要研究氮
See, not all nitrogen is the same.
你知道吗 并非所有的氮都一样
Some nitrogen atoms have more neutrons than others.
某些氮原子比另一些氮原子拥有更多的中子
And it turns out nitrogen atoms can have
氮原子可以有7到8个
either seven or eight neutrons and remain stable—
保持稳定的中子
so nitrogen has what chemists call two stable isotopes.
因此氮原子含有化学家所说的两种稳定同位素
Over 99% of the nitrogen on Earth is the lighter kind: nitrogen-14.
地球上99%以上的氮都是较轻的氮14
But salmon have a weirdly high amount of nitrogen-15,
与陆地生物相比
when compared with land-dwelling species.
鲑鱼体内的氮15含量高得出奇
That’s partly because most salmon spend
部分原因是 大多数鲑鱼成年后
nearly all of their adult life in the ocean,
几乎都生活在海洋中
and it just so happens that
而和陆地相比 因为海水会出现
the chemical and biological processes that
化学和生物的反应过程
occur in seawater make more nitrogen-15 available there than on land.
所以海洋的氮15含量更多
On top of that, though you may not
最重要的是 尽管你可能认为
think of salmon as fierce predators,
鲑鱼不是凶猛的捕食者
they’re actually pretty high up the food chain.
但它们实际上在食物链中的位置相当高
And animals use each nitrogen isotope slightly differently.
动物对每种氮同位素的使用稍有不同
Because of quirks of biochemistry we don’t fully understand,
由于我们并不完全了解的生物化学的特性
nitrogen-14 tends to be excreted more than nitrogen-15.
氮14比氮15更容易被排出体外
And since this happens at every level of the food chain,
这种现象在食物链的每一层都会发生
the higher up animals are,
食物链地位越高
the more nitrogen-15 they have in their diet
它们食物中的氮15含量越高
— and therefore, in their bodies.
因此它们体内的氮15含量也就越高
Starting in the late 1990s,
20世纪90年代末以来
research revealed that
研究发现 在阿拉斯加溪流附近的
trees near salmon streams in Alaska
有鲑鱼聚集的树木
have impressively high levels of nitrogen-15.
含有大量的氮15
The obvious conclusion:
研究结论显而易见:
they get a lot of their nutrients from salmon!
这些树从鲑鱼体内汲取了大量营养
And that wasn’t all.
这还不是全部真相
By looking at nitrogen in individual tree rings—
如果把一棵树砍成两半
those yearly layers you can see if you cut a tree in half —
你可以看到年轮
the researchers were able to show
研究每棵树年轮中的氮含量
how important salmon are to the trees.
研究人员就能证明鲑鱼对树有多重要
During and after years when more fish came upstream to spawn,
经过数年 更多的鲑鱼游到上游产卵时
the trees grew bigger rings with more nitrogen in them.
树就会长出更宽的 氮含量更多的年轮
And overall, trees that received nutrients from salmon
总的来说 能够从鲑鱼中汲取营养的树木
grew 19% bigger than those that didn’t!
比那些无法汲取营养的树木高出19%
So, if you’re a tree who wants to grow nice and tall,
所以 如果你是一棵希望长得又高又茂盛的树
you’d better not skip out on the sushi.
最好不要错过鲑鱼寿司盛宴
But if you’re a human who’s been inspired
如果你因受本期节目启发
by this episode to dive deeper into biochemistry,
而更深入地研究生物化学
well, that’s something today’s sponsor—Brilliant.org—can help with.
那么今天的赞助商可以为你提供帮助
for example, You could take their course on chemical reactions
例如 你可以听他们的化学反应课程
and learn about molecules and how they interact.
学习分子及其相互作用
And it’s just one of the fun, interactive courses
这是一个有趣的互动课程
you can take with a Premium subscription.
你可以享受优惠价格订阅哦
That sounds a cup of tea,
这不过是小意思
I have got some good news for you.
我有好消息告诉你
The first 200 people to sign up at Brilliant.org/SciShow
前200名注册Brilliant.org/SciShow的用户
will get 20% off the annual Premium subscription.
将获得20%的年费优惠
Head over there,check it out and see if it’s right for you.
赶紧去查阅吧 看看有什么适合你的课程

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