The sharks that hunt in forests - Luka Seamus Wright

翻译人员: Frank Xu 校对人员: Helen Chang

In the coastal waters of the Bahamas,

在巴哈马沿海水域，

a young lemon shark is on the run from a surprising predator:

一条幼年柠檬鲨正在躲避 一个令人意外的捕猎者：

an adult shark of her own species.

一条成年的柠檬鲨。

Half of her 17 siblings have already been eaten by the older generation,

她17个兄弟姐妹中的半数 已经被前辈吞食，

and it looks as though she’s about to join them.

而现在似乎牠也即将加入牠们的行列。

But just as the predator closes in,

但正当捕食者逼近之时，

she disappears into a thicket of underwater roots,

牠消失于一片茂密的水下根茎之中，

safe in the refuge of the mangrove forest.

安全地藏于红树林的庇护之中。

Forests don’t usually come to mind as a habitat for sharks.

几乎没有人会把森林 和鲨鱼的栖息地联想起来，

But various marine forests cover roughly 4.2 million square kilometers

但多种海上森林覆盖了这座星球，

of the planet,

约420万平方公里的面积，

providing food and shelter for 35% of the world’s sharks.

为世界上35%的鲨鱼 提供食物和栖息地。

Deadly tiger sharks blend into seagrass meadows

致命的虎鲨们在 猛扑向海牛和海龟之前

before pouncing on sea cows and sea turtles.

埋伏在海草丛中。

White sharks hunt down seals in forests of kelp towering 65 meters tall.

白鲨在高达65米的 海带林里狩猎海豹。

And lemon sharks stalk forests of mangroves—

而柠檬鲨则穿梭在红树林中——

the only trees on Earth that live in the ocean.

地球上唯一活在海里的树。

All these ecosystems have their quirks,

所有这些生态系统 都有着自己的神奇之处，

but mangroves may be the most unique of all.

但是红树林可能是最独特的。

Harboring life between their roots and among their crowns,

它们的树根与树冠为生命提供庇护，

mangroves function as an essential bridge between land and sea.

红树林行使着 衔接海陆的重要桥梁的功能。

And to survive between these worlds, different mangrove species

而为了在这些世界里生存， 不同种类的红树林

have evolved various adaptations that protect them and their resident sharks.

进化出了多种保护它们本身 和寄宿鲨鱼们的适应特性。

Taking root in the unstable ground of muddy coastal regions is difficult,

在泥泞的海岸地区中 不稳定的大地上扎根是困难的，

so mangrove seedlings germinate attached to their mother plant.

因此红树幼苗缠在红树妈妈上发芽。

Once they've grown large enough to survive on their own,

在它们长大到能够独自生存时，

these partially developed plants begin to ride the current.

这些部分发育过的植物 开始随浪漂流。

Most take root nearby, while some travel for several months

大多数在附近扎根， 而有些则漂流数月

before landing in a different part of the world.

直到到达世界不同的角落。

Once they’ve settled down, mangroves deploy tall, skinny stilt roots,

在它们安定下来后， 红树们长出高大，细长的高跷根，

crutch-like prop roots or wavy buttress roots,

形似拐杖的支柱根， 或者弯曲的扶壁根，

to support themselves in their unsteady terrain.

以在不稳的地形中支撑它们自己。

These newly established mangroves have to contend with two additional problems:

这些新长成的红树林 需要与额外两个问题斗争：

seawater is high in dehydrating and potentially toxic salt,

海水富含会导致脱水 甚至可能具有毒性的盐类，

and the mud contains little to no oxygen.

且泥地含有过少或完全不含氧。

This combination would be lethal to most trees,

这两个问题合在一起 对大多树木来讲会是致命的，

but mangroves make the most of their marshy surroundings.

但是红树林充分利用 它们泥泞的环境。

Rather than being completely buried,

相比完全埋在地下，

mangrove roots are largely above the ground.

红树根大部分位于地表之上。

This allows the microscopic pores on these roots to take in oxygen during low tide

这允许这些树根上的 微小气孔在低潮时能吸入氧气

before closing to create a waterproof seal during high tide.

并在涨潮前关闭以防止水分进入。

Many mangroves also grow snorkel roots,

很多红树还长有通气根，

which can take in oxygen through the same mechanism,

它们能通过相同原理来吸入氧气，

or directly produce it via photosynthesis.

抑或使用光合作用来直接产氧。

To stop salt from entering their system,

为了阻止盐分进入它们的系统，

some mangrove species use incredibly fine filters in their roots.

有些红树种类使用 它们根部中极细的过滤器。

Others concentrate salt inside special cellular compartments,

其它的则将盐浓缩到特殊的细胞室、

bark or dying leaves, that then drop off.

树皮或将枯萎并掉落的树叶里。

Some species can even excrete the excess minerals

有些品种甚至能通过特别进化的盐腺

through specially adapted salt glands.

排出多余的矿物质。

All these processes make mangroves more than a little salty,

所有这些过程把红树林变得咸咸的，

but that doesn’t deter coastal life from living in their nooks and crannies.

但这并不阻止海岸生物 在它们的角落和缝隙里生活。

While birds nest among mangrove branches,

鸟儿们在红树枝间筑巢，

fish lay eggs amidst their sprawling, complex root systems.

鱼儿们在它错综复杂的根系间产卵。

Symbiotic sponges and sea squirts protect their host trees

共生海绵和海乌贼保护它们的宿主树

from hungry woodboring crustaceans.

免受饥饿且爱钻木头的甲壳动物伤害。

Crabs, snails, and shrimp eat algae, mussels, barnacles,

螃蟹、螺，和虾 吃海藻、青口贝、藤壶

and salty mangrove detritus.

还有咸咸的红树残渣。

These animals in turn feed fish,

这些小动物则喂饱鱼类，

which are devoured by shark pups roaming the roots—

后者被在树根间游荡的 鲨鱼幼崽吞食——

alongside occasional vegetarian meals of seagrass.

鲨鱼们有时还吃海草素食餐。

But sharks aren’t just the beneficiaries of marine forests,

但鲨鱼不是海中林的唯一受益者，

they’re part of the glue that holds them together.

牠们也是保持红树林生态的 重要“粘合剂”之一。

Sharks limit the abundance of animals

鲨鱼限制动物的数量，

which would otherwise overgraze these essential plants.

否则太多的动物 会过度消耗这些重要植物。

Just as marine forests provide shelter to vulnerable baby predators,

就像海中林为脆弱的 猎食动物宝宝提供庇护所，

those predators grow up to protect their forest homes.

这些猎食者长大后 保护牠们的森林之家。

Unfortunately, both sides of this delicate balance are under threat.

不幸的是， 这精妙平衡的双方都正遭受威胁。

Overfishing has decimated shark populations worldwide,

过度捕鱼在世界范围 大幅减少了鲨鱼数量，

and many marine forests are being polluted or cut down for coastal development.

并且很多海中林正在 因为沿海开发而被砍伐和污染。

This destruction is especially dangerous

这些破坏特别危险

because marine forests are one of the single most important ecosystems

因为海中林对于减轻环境变化来说，

in mitigating climate change.

是最重要的生态系统。

Mangroves and seagrasses trap carbon between their roots,

红树林和海草林在根系中困住碳，

and fast-growing kelps export vast amounts of carbon to the deep ocean.

而长得飞快的海带 将大量碳输出到深海区域。

Together, marine forests sequester around 310 million tonnes of carbon every year,

算在一起，海中林每年 将大约310万吨碳隔绝起来，

capturing 3% of our annual global carbon emissions.

捕获我们每年 全球碳排放的百分之三。

So, like the sharks that inhabit them,

所以，就像栖息在它们中的鲨鱼，

humans need to fight tooth and nail to protect these essential ecosystems.

人类需要极尽全力 来保护这些重要的生态系统。