The sharks that hunt in forests - Luka Seamus Wright

譯者: Samantha Cheng 審譯者: Amanda Zhu

In the coastal waters of the Bahamas,

在巴哈馬海岸的水域，

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

一條年輕的檸檬鯊正在逃離 一個令人意想不到的捕食者：

an adult shark of her own species.

一條跟自己同種的成年鯊魚。

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

在她 17 個兄弟姐妹當中， 有一半已經被老一輩的鯊魚吃掉了。

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

而她的命運看似即將與牠們一樣。

但是，就在捕食者要逼近時，

But just as the predator closes in,

she disappears into a thicket of underwater roots,

她消失於一叢水下的樹根中，

safe in the refuge of the mangrove forest.

在紅樹林的掩護下，安全無恙。

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

我們都想不到鯊魚 會把森林當作棲息地。

But various marine forests cover roughly 4.2 million square kilometers

但是各種海洋森林大約覆蓋了 地球的 4.2 萬平方公里，

of the planet,

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

為全球 35% 的鯊魚提供食物和住所。

Deadly tiger sharks blend into seagrass meadows

致命的虎鯊突襲海牛和海龜前，

before pouncing on sea cows and sea turtles.

會先將自己隱藏在海草床裏。

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

大白鯊在高達 65 米的 海帶森林中捕殺海豹。

And lemon sharks stalk forests of mangroves—

而檸檬鯊潜伏於紅樹林中——

the only trees on Earth that live in the ocean.

地球上唯一生活在海洋裏的樹木。

All these ecosystems have their quirks,

這些生態系統都有它們的怪異之處，

but mangroves may be the most unique of all.

但紅樹林可能是最獨特的。

Harboring life between their roots and among their crowns,

紅樹林的根部和樹冠之間庇護著生物，

mangroves function as an essential bridge between land and sea.

它們是陸地和海洋之間的重要橋梁。

And to survive between these worlds, different mangrove species

為了在陸地和海洋之間生存， 不同種的紅樹林

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

演化出各種適應能力， 以保護自己和居住在内的鯊魚。

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

紅樹林要在不穩定而泥濘的 沿海地區扎根是很難的,

so mangrove seedlings germinate attached to their mother plant.

所以紅樹林的幼苗發芽時， 還附著在母株上。

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

它們一旦長得夠大，足以獨立生存，

these partially developed plants begin to ride the current.

這些已經發育了一部分的植物 就會開始順著海流移動，

Most take root nearby, while some travel for several months

大多數都會在附近扎根， 有些則會在漂流數月後，

before landing in a different part of the world.

才在世界另一個地方停下來。

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

它們一旦安頓下來， 紅樹林就會長出高而瘦的高蹺根，

crutch-like prop roots or wavy buttress roots,

像拐杖形狀的支柱根 或者是波浪狀的版根，

to support themselves in their unsteady terrain.

以便在不穩定的地形支撐自己。

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

這些剛長成的紅樹林 必須應付另外兩個問題：

seawater is high in dehydrating and potentially toxic salt,

海水含有大量導致脫水 和可能有毒的鹽，

and the mud contains little to no oxygen.

而且泥土裏幾乎沒有任何氧氣。

This combination would be lethal to most trees,

這個組合會對大部分的樹木 造成致命的傷害，

but mangroves make the most of their marshy surroundings.

但是紅樹林能充分利用 沼澤濕地的環境，

Rather than being completely buried,

它的根部大部分都是在地面之上，

mangrove roots are largely above the ground.

而不是完全被埋在地下。

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

這讓樹根上的微小氣孔 在退潮時吸收氧氣，

before closing to create a waterproof seal during high tide.

然後在潮漲時將氣孔關閉， 變成防水的密封狀態。

Many mangroves also grow snorkel roots,

許多紅樹林也有浮潛根，

which can take in oxygen through the same mechanism,

也可以透過同樣的機制來吸收氧氣，

or directly produce it via photosynthesis.

或行光合作用直接生產氧氣。

To stop salt from entering their system,

為了防止海水中的鹽進入植株內，

some mangrove species use incredibly fine filters in their roots.

有些種類的紅樹林會利用 位於根部裏極細密的過濾器，

Others concentrate salt inside special cellular compartments,

其他則會將鹽集中於 特殊的細胞隔室、樹皮

bark or dying leaves, that then drop off.

或即將枯萎的葉子裏， 然後讓它們脫落。

Some species can even excrete the excess minerals

有些種類甚至演化出特有的鹽腺，

through specially adapted salt glands.

來排出過量的礦物質。

All these processes make mangroves more than a little salty,

這些過程使紅樹林鹽味很重，

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

但是這並不會阻止沿海生物生活在 紅樹林的每個角落和縫隙中。

While birds nest among mangrove branches,

鳥兒在紅樹林的樹枝之間築巢，

fish lay eggs amidst their sprawling, complex root systems.

魚兒則在錯綜複雜的根系中產卵。

Symbiotic sponges and sea squirts protect their host trees

共生的海綿和海鞘 保護牠們紅樹林宿主

from hungry woodboring crustaceans.

免受會啃食木頭的甲殼類動物侵害。

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

螃蟹、蝸牛和蝦會吃 藻類、貽貝、藤壺和鹹的紅樹林碎屑。

and salty mangrove detritus.

These animals in turn feed fish,

這些動物則是魚的糧食，

which are devoured by shark pups roaming the roots—

而魚又會被漫遊在根部的幼鯊吃掉，

alongside occasional vegetarian meals of seagrass.

幼鯊偶爾還會吃素，以海草為食。

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

但鯊魚不僅是海洋森林的受益者，

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

牠們也協助維繫海洋森林的存續。

Sharks limit the abundance of animals

鯊魚限制動物的數量，

which would otherwise overgraze these essential plants.

否則會過度消耗這些不可或缺的植物。

Just as marine forests provide shelter to vulnerable baby predators,

就像海洋森林為脆弱的年幼捕食者 提供庇護所一樣，

those predators grow up to protect their forest homes.

這些捕食者長大後， 會保護它們的森林居所。

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

可惜這微妙的平衡正受到威脅。

Overfishing has decimated shark populations worldwide,

過魚使全球鯊魚的數量大大削減，

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

而許多海洋森林因為沿海地區的開發 而受到污染或被斬伐。

This destruction is especially dangerous

這樣的破壞特別危險，

because marine forests are one of the single most important ecosystems

因為海洋森林是緩解氣候變遷 最重要的生態系統之一。

in mitigating climate change.

Mangroves and seagrasses trap carbon between their roots,

紅樹林和海草會在根部之間把碳留住，

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

而快速生長的海帶會把 大量的碳送往深海。

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

海洋森林每年共儲存了 大約 3.1 億公噸的碳，

capturing 3% of our annual global carbon emissions.

捕集了我們每年全球碳排放量的 3%。

So, like the sharks that inhabit them,

所以，就像居住在這些森林的鯊魚，

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

人類也要竭盡全力保護 這些重要的生態系統。