The big-beaked, rock-munching fish that protect coral reefs - Mike Gil

470,958 views ・ 2020-08-04

TED-Ed


請雙擊下方英文字幕播放視頻。

譯者: Lilian Chiu 審譯者: Helen Chang
00:07
As the sun rises over a quiet coral reef, one animal breaks the morning silence.
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隨著太陽升起到 安靜的珊瑚礁上方,
一隻動物打破了早晨的寧靜。
00:13
Named for their vibrant scales and beak-like teeth,
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這些鸚哥魚的名字來自牠們 顏色鮮明的鱗片及像鳥喙般的牙齒,
00:16
these parrotfish are devouring a particularly crunchy breakfast: rocks.
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牠們正在狼吞虎嚥地吃 一種特別酥脆的早餐:
石頭。
00:22
It may not be immediately clear why any creature would take bites
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或許無法馬上理解為什麼
有任何生物會想要去啃食海底。
00:26
out of the seafloor.
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00:28
But the diet of these flashy foragers actually plays a key role
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但這些俗豔的搶食者 其實扮演了一個關鍵角色:
00:32
in defending the coral reef’s complex ecosystem.
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保衛珊瑚礁的複雜生態系統。
00:36
Massive coral reefs begin with tiny coral larvae,
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大型珊瑚礁一開始 也只是小型的珊瑚幼蟲,
00:40
which settle on the seafloor’s hard surfaces
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幼蟲住在海底的堅硬表面上,
00:42
and metamorphasize into coral polyps.
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變態成為珊瑚蟲。
00:46
Over time, these polyps generate rock-like skeletons
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隨時間,這些珊瑚蟲 會產生像岩石一樣的骨骼,
00:49
made of calcium carbonate.
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骨骼由碳酸鈣構成。
00:51
Together, colonies of polyps produce large three-dimensional structures,
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成群的珊瑚蟲一起製造出 大型的立體結構,
00:56
which form the basis of an underwater metropolis.
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成為水中都市的基礎。
00:59
These coral complexes are full of nooks and crannies
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這些珊瑚構成的結構中 滿是隱蔽處和裂縫,
01:03
that house and protect countless life forms.
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成為無數生命形式的住處和庇護。
01:06
Even though coral reefs occupy less than one percent of the ocean floor,
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雖然珊瑚礁只佔據 不到 1% 的海底面積,
01:10
these dense ecosystems are home to more than twenty-five percent of marine life.
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有超過 25% 的海洋生命
以這些稠密的生態系統為家。
01:16
Many fish use corals as shelters for sleeping and to hide from large predators
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許多魚類用珊瑚當作 庇護所,可以在裡面睡覺,
也可以在搜尋海草的過程中 到此躲避捕食性動物。
01:22
between their trips foraging for seaweed.
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01:24
As the primary food source for many of the reef’s fish and invertebrates,
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海草是許多珊瑚礁魚類 及無脊椎動物的主要食物來源,
01:29
seaweed is vital to this ecosystem.
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對於這個生態系統極其重要。
01:31
But in high densities, seaweed can become problematic,
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但若密度過高, 海草有可能帶來麻煩,
01:35
and even lethal to corals.
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甚至會造成珊瑚死亡。
01:37
Seaweed grows on the same hard open surfaces that coral larvae rely on,
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海草就生長在珊瑚幼蟲 所仰賴的堅硬開放表面上,
01:42
and their growth prevents new coral from settling and expanding.
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海草的生長會阻撓 新的珊瑚定居、拓展。
01:46
These competitors have also evolved a variety of ways to kill existing corals,
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這些競爭者也演化出多種 可以殺死既有珊瑚的方式,
01:51
including smothering and abrasion.
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包括造成窒息以及磨損。
01:54
Some seaweed species even engage in chemical warfare—
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有些種類的海草 甚至會打化學戰——
01:57
synthesizing compounds that destroy coral on contact.
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合成一些化合物來摧毀 它們接觸到的珊瑚。
02:02
This is where parrotfish come in.
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此時就該鸚哥魚登場了。
02:04
Like many reef fish, these colorful creatures eat seaweed.
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和許多珊瑚礁魚類一樣, 這些多彩的生物也吃海草維生。
02:08
But unlike their neighbors,
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但和牠們的鄰居不同,
02:10
parrotfish can completely remove even the tiniest scraps of seaweed
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鸚哥魚能夠將海草從海底除去,
乾淨到一點都不剩。
02:14
from the ocean floor.
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02:16
Their so-called beak is actually a mosaic of tightly-packed teeth
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牠們所謂的喙,其實是 緊緊鑲嵌在一起的牙齒,
02:21
which can scrape and grind rock,
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能夠刮落、磨碎岩石,
02:23
allowing them to consume every bit of seaweed covering a stony surface.
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讓牠們可以將覆蓋在石頭 表面上的所有海草都吃光。
02:28
This helps parrotfish reach seaweed other fish can’t consume,
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這個特點讓鸚哥魚能夠吃到 其他魚類無法吃到的海草,
02:32
while simultaneously clearing out open space for new corals
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同時,還能為新珊瑚 清理出開放空間,
讓新珊瑚定居,讓既有珊瑚拓展。
02:36
to settle and existing colonies to expand.
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02:39
Eating rocks is just one way parrotfish help manage seaweed.
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吃岩石只是鸚哥魚 協助整理海草的方式之一。
02:43
Through a dynamic system of social networks,
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透過社交網路的動態系統,
02:46
parrotfish can convey information to other coral dwelling fish.
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鸚哥魚可以傳遞資訊給 其他住在珊瑚中的魚類。
02:50
Each fish’s presence and simple routine behaviors produce sensory information
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每條魚的出現及簡單的例行行為 都會產生出感官資訊,
02:55
that nearby fish can see, hear, or smell.
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鄰近的魚類可以 看見、聽見,或聞到。
02:59
They can even detect changes in water pressure produced by their neighbors
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牠們甚至可以用 一種特殊的感覺器官
來偵測鄰居造成的水壓改變。
03:03
using a special sensory organ.
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03:05
All these factors can inform the behavior of nearby fish.
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所有這些因素,都能傳遞 鄰近魚類的行為資訊。
03:09
For example, a fish safely entering an open feeding ground
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比如,一條魚安全地 進入了開放的攝食場,
03:13
and not getting attacked means it’s safe to forage.
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且沒有遭受攻擊,就表示 可以安心在那裡覓食。
03:17
Conversely, a fish rapidly leaving a location can provide an early warning
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相反的,一條魚快速離開某個地點,
就是一種預先警示, 表示有威脅迫近。
03:21
that a threat is approaching.
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03:23
By simply trying to stay alive,
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這些珊瑚礁魚類只是 單純地試圖活下去,
03:25
these reef fish can incidentally help their neighbors survive—
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無意間也協助了 牠們的鄰居求生存——
03:29
and more of these fish means less seaweed.
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而這些魚類越多,就表示海草越少。
03:32
Unfortunately, human activities over the last several decades
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不幸的是,在過去 數十年間的人類活動
03:36
have disrupted almost every part of this complex system.
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幾乎把這個複雜系統的 每個部分都破壞了。
03:39
In many coral reefs, overfishing has reduced the number of parrotfish,
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在許多珊瑚礁地區,過度捕撈 已經造成鸚哥魚數量減少,
03:44
as well as other seaweed eaters, such as surgeonfish and rabbitfish.
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其他吃海草的生物如刺尾鯛魚 及籃子魚也同樣不斷減少。
03:48
This has led to unchecked seaweed growth,
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這個現象導致海草 可以無法無天地生長,
03:51
which threatens to degrade entire coral reefs.
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因而產生讓整個 珊瑚礁劣化的威脅。
03:54
The parrotfish that remain live in much smaller communities.
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剩下的鸚哥魚生活在 小很多的群落中。
03:58
Their reduced numbers can weaken their social network,
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牠們的數量減少,會導致 牠們的社交網路變弱,
04:01
making surviving fish more timid and less effective at controlling seaweed.
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讓存活下來的魚類更膽怯, 且無法有效控制海草。
04:06
Today, climate change and pollution are lowering coral’s natural defenses
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現今,氣候變遷和污染都造成 珊瑚的天然防禦能力下降,
04:10
while contributing to runaway seaweed growth—
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同時讓海草的生長遙遙領先——
04:13
leaving reef ecosystems more fragile than ever.
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造成珊瑚礁生態系統 比以往都更脆弱。
04:17
Our reefs are vitally important to both marine and human life.
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珊瑚礁對於海洋生命 及人類生命都極其重要。
04:21
Their unparalleled biodiversity offers unique opportunities for ecotourism,
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它們無比的生物多樣性,提供了 獨特的機會,可以做生態旅遊、
04:26
sustainable fishing, and scientific research,
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永續捕魚,以及科學研究,
04:29
while their rocky structures guard coastlines from waves and storm surges.
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同時它們的岩石結構能保衞 海岸線,對抗海浪和暴潮。
04:34
Fortunately, continued research into reef species
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幸運的是,持續研究珊瑚礁物種,
04:37
like the quirky and critical parrotfish can inform new strategies
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比如多變又重要的鸚哥魚,
提供的資訊可以用來制訂策略, 以保存這些重要的生態系統。
04:41
for preserving these essential ecosystems.
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