地球壮观河流之旅（2019）

它们会附在鱼鳃上数周时间
They will hitch a ride on the fish's gills for a few weeks
然后就会脱落下来
before finally dropping off.
大鱼在不经意间让河蚌幼体
The fish unwittingly spread the young mussels
散布在河床上
up and down the river bed.
这绝对是地球上最非凡的育儿策略
Surely, one of the most extraordinary parenting strategies
之一
on Earth.
春季上涨的河水为北方地区的
The rising waters of spring provide opportunities
许多水生生物提供了生机
for many river creatures right across the north.
但对另一些生物而言春季的冰雪融化并不那么受欢迎
But, for others, the spring melt is not so welcome.
密西西比河流域内都有河狸生活
Beavers are found throughout the Mississippi Basin.
它们会在巢穴附近修建水坝 就像是一道护城河
They build dams to create a watery moat around their homes,
可以帮助它们防御那些或许会从陆地上发起进攻的捕食者
which protects them from predators that could attack from the land.
在它们的巢穴里面
Inside their homes, known as lodges,
成年河狸和幼崽们安全又温暖
adults and their kits stay safe and warm.
但它们的宁静生活即将被打破
But their peace is about to be shattered.
河狸从流水声中察觉到了危险
The beavers can hear there's a problem.
研究者发现 对河狸来说流水声
Researchers have found that the sound of running water
是很重要的预警
is something that beavers are simply unable to ignore.
那种声音意味着它们珍贵的水坝正处于
The sound means their precious dams are in danger of being swept away
被湍流冲毁的危险中
by the swelling streams.
它们的护城河会排空
Their moats could drain away,
使它们的家园失去水的保护而受到捕食者的威胁
leaving their lodges high and dry and at risk from predators.
河狸必须加班加点努力啃咬树枝 尽可能多的
The beavers must gnaw, drag and pack as much fresh material
往水坝拖拽并填补新材料
into the dams as they can,
试图阻止水流
to try and staunch the flow.
河狸的一生几乎都在努力阻挡河水
Beavers spend their whole lives trying to block the river.
但最后
But in the end,
河水总是胜出的那一方
the river always wins.
人类试图掌控密西西比河支流上
Humans have also tried to control the powerful waters
汹涌的河水
of the Mississippi's tributaries.
建起了水坝 比如位于落基山脉的这些
Building dams like these in the foothills of the Rockies.
它们有许多被用来储存冰雪融水
Many are used to store meltwater for irrigation
以便在干旱的夏季用来灌溉农田
in the dry summer months.
但是当密西西比河的河水向下游流动时
But not even these 100-metre-high walls
即便这些百米高的水坝也没有办法
can entirely contain the Mississippi's water
完全容纳这些河水
on its journey downstream.
水坝反而会扰乱河水的自然流动
Damming rivers disrupts their natural flow.
不过在距离落基山脉东部1600公里的
But here, Marsh Lake in Minnesota,
明尼苏达州 坐落在马什湖的水坝
nearly 1,000 miles downstream from the Rockies,
为一些生物提供了意外的机会
it's created an unexpected opportunity for some.
美洲白鹈鹕
American white pelicans.
它们的翼展长达三米 每年春季都飞到这里来
They arrive here each spring on three metre wingspans.
有些白鹈鹕要飞行3200公里才能来到这里
Some of them have flown over 2,000 miles just to get here.
它们的巢穴四周环水 可以防御捕食者
Their nests are protected from predators by the surrounding waters.
大约22000只美洲白鹈鹕将这个小岛挤得满满的
22,000 of them cram onto the islands.
它们已经做好了繁殖的准备
As a sign that they're ready to breed,
其中一个信♥号♥♥就是雄性及雌性的喙上会长出一种特别的角
both males and females grow a special horn on their bills.
这种角会在产卵后脱落
Which drops off after their eggs have been laid.
马什湖的水坝不仅为它们提供了保护
But Marsh Lake's dam offers more than protection.
还迫使洄游的鱼类在通过水坝时不得不通过狭窄的间隙
It forces migrating fish to pass through a narrow gap,
这使得鱼类全部集中在一处
concentrating them all in one place.
而美洲白鹈鹕有着众所周知的大胃口
And pelicans are famed for their appetite.
游经水坝的一些鲤鱼甚至长达一米
Some of the carp funnelled across the dam can be over a metre long.
只要有一只美洲白鹈鹕找到了大小合适的鱼
But when one pelican finds more suitably sized fish,
它们就会一哄而上
it's the cue for them all to pile in.
配乐：罗西尼 塞维利亚理发师 序曲
MUSIC: The Barber of Seville Overture by Rossini
丰富的食物资源为饥饿的
The bonanza provides a welcome meal
幼鸟们提供了大餐
for the hungry chicks.
等到幼鸟长出羽毛后
After their young have fledged,
成年的美洲白鹈鹕就会离去
these pelicans will leave.
它们会飞往密西西比河的干流
They'll fly towards the main channel of the Mississippi River,
并依靠干流的流向作为自己的指南针飞往遥远的南方
using it to help navigate on their long journey south.
离开荒芜的上游河段后
As they leave its wild, upper reaches,
密西西比河的诸多支流开始汇聚到干流里
the Mississippi's tributaries begin to funnel into the main channel.
这里距河口约有3200公里
Here, around 2,000 miles from the river's mouth,
密西西比河流经了美国农业的中心地带
the Mississippi passes into the farming heartland of the USA.
美国出口的农产品有92%
92% of America's agricultural exports
产自密西西比河流域
are produced within the Mississippi Basin.
艾奥瓦州 伊利诺伊州以及威斯康星州等地的人们种植了各种作物
States like Iowa, Illinois, Wisconsin growing everything...
比如大豆 蔓越莓等
..from grain to soybeans to cranberries.
威斯康星州出产了全世界一半以上的蔓越莓
Wisconsin produces over half the world's cranberries.
一直以来这里的蔓越莓产业主要依赖密西西比河的河水
Historically, this industry relied on the Mississippi's water.
果实成熟后 种植蔓越莓的农田会被刻意淹没
When the fruit is ripe, the fields are deliberately flooded.
这时蔓越莓漂浮在水面上
The cranberries float to the top,
最终被挑拣出来 出口到世界各地
ready to be skimmed off the surface and exported across the globe.
密西西比河的中段为整个美国提供了食物
The central stretch of the Mississippi helps to feed the entire nation.
也同时为野生动物提供了丰富的资源
And is a fertile home for wildlife, too.
每年的七月初
Each year, around the 4th of July,
一种小型昆虫会在这里上演令人惊叹的大戏
tiny insects put on an amazing show.
这是蜉蝣
Mayflies.
蜉蝣若虫已经在河床上生长了两年
Their nymphs have lived on the riverbed for up to two years,
它们逐渐长大 做好了飞向空中的准备
slowly maturing, preparing to sprout wings and take to the air together.
数百万只蜉蝣同时出现聚为一大群
Millions emerge simultaneously in swarms so big,
气象雷达都能发现它们
they can be seen on weather radar.
但离开河水后它们的生命是很短暂的
But their independence from the river is short lived.
蜉蝣聚集在一起是为了交♥配♥
They emerge simply to mate,
而后雌性蜉蝣会回到河中产卵
after which the females must return to lay their eggs.
在首次从水面亮相的两天后
Just two days after they first appeared,
蜉蝣短暂而灿烂的一生就结束了
the final, spectacular stage of their life will be over.
早在人类定居之前
Mayflies have risen from the river
蜉蝣就已经在这一河段的水面上盘旋
since long before people settled here.
但如今的密西西比河
But those that emerge today
却深受这些现代居民的影响
are surrounded by the modern face of the Mississippi.
这一河段是整个干流中最深的部分
This central stretch is the steepest section of the main river channel.
为了保持水的深度以便航运
To keep the waters deep enough for transport,
河面上修建了巨型船闸和水坝
giant locks and dams have been built right across it.
曾经狂野奔腾的河流
What was once a wild, rushing river
变成了悠然前行的宽广运河
has become a huge, sluggish canal.
川流不息的大型货船
Today, an endless stream of massive barges
装载着数百万吨♥的货物
move millions of tonnes of the nation's produce
在美国境内奔走着
up and down the length of the country.
生活在这里的人们
Whole communities live and rely
都依赖于工业化的密西西比河
on the industrialised Mississippi,
约翰-希尔-加特纳船长就是其中一位
including captain John Hill Gardner.
我们所有人的生活都依靠着这条河
All these people are dependent on the river for their livelihood.
大家都要谋生 是这条河给了我们生活的保障
We all have a living and it gives us a living.
我们的工作时间很长工作也很辛苦
The hours are long. The work's hard.
但是每次回到这里就感觉就像回到家里
When you come back, it's like you're coming back to your home.
这是一种生活方式
It's just a way of life.
四通八达的河流带来了繁荣的贸易
Fed by trade on the river,
因而密西西比河沿岸也诞生了许多热闹的城市
bustling cities have grown up all along its banks.
密西西比河最长的支流密苏里河就在这里交汇
Halfway down the Mississippi, St Louis was built where
圣路易斯就建在那里
the longest of the river's tributaries, the Missouri, joins the main channel.
粮食从美国中部集聚到这里
Grain is trucked here from across the central USA,
然后运向世界其它地方
destined for the rest of the world.
在河面上 拖船的船长们调控着空仓的大型货船
On the river, tugboat captains wrangle huge, empty barges.
每艘货船能运载1500吨♥粮食或大豆
A single barge can carry 1,500 tonnes of grain or soy.
装载完毕后
Once loading is finished,
这些货船被成群结队地托运走
the barges are shuffled together in giant flotillas.
每支船队都有四个足球场那么大
Each one can cover the area of four football pitches
长度超过350米
and be over 350 metres long.
多亏了河流地帮助 只需一艘船就能拖动
Thanks to the river's help, the whole flotilla can be pushed
整支船队 这支船队地运力相当于
by a single boat, hauling as much cargo in one journey
2500辆卡车
as over 2,500 trucks.
船队将沿着密西西比河行驶数千公里
A boat trip down the Mississippi is nearly 2,000 miles long.
这要两周时间 就要船员具备专注力
It can take two weeks and requires concentration,
耐力和充足地经验
experience and stamina.
这里地运营从不停歇
We work out here in a nonstop operation.
每天24小时每周7天每年365天
It goes 24/7, 365 days a year.
我们每工作6小时就休息6小时
We work six hours on, six hours off,