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  • [♪ INTRO]

  • When you imagine an ecosystem,

  • you might picture an old-growth forest, or maybe a coral reef.

  • But an ecosystem can be any place

  • where living things interact with each other and their environment.

  • It can be very small, like a single tide pool, or very large, like an entire grassland.

  • It can also be very odd.

  • Around the world, living things have managed to build truly extraordinary ecosystems

  • in some of the last places you would think to look.

  • Here are five unusual ecosystems that just go to show

  • how innovative and adaptable life really is!

  • Along the West Coast of the U.S., trees called coast redwoods

  • grow taller than any other tree in the world;

  • sometimes reaching up to 37 stories high.

  • People have admired these trees for a long time,

  • but we've only recently started to pay attention to

  • what's actually happening way up at the tops of them.

  • In fact, it took til the late 1990s

  • before people began exploring these redwood canopies because, well,

  • scooting up a tree that's nearly as tall as a skyscraper isn't your typical field work.

  • But when people finally got up there, they found way more than they expected.

  • In fact, redwood trees were so large, and extended so far from the ground,

  • that their canopies had become ecosystems of their own.

  • Scientists essentially found a forest growing on top of a forest,

  • completely hidden from sight on the ground.

  • Up in the canopy, single trees split into multiple trunks.

  • In one study, researchers counted 137 trunks growing out of a single tree.

  • These aren't, like, little scrawny things, either.

  • The trunks of these trees can be a meter wide,

  • so you probably couldn't tell them apart from trees on the forest floor,

  • except that they're 50 meters or more up in the air.

  • These weren't just redwoods, either.

  • Trees of all different species, like Sitka spruce and Douglas fir,

  • grew off of the redwoods' branches.

  • Researchers even found a California bay laurel tree

  • with its roots some 98 meters above ground!

  • And these trees can grow here because there is actually soil to grow in!

  • Canopy branches grow really wide, sometimes two meters across,

  • and they can get covered in ferns.

  • Over time, these so-called fern mats trap dead branches, and broken trunks, and other debris,

  • building up a layer of soil and organic material, a lot like what's on the forest floor.

  • And, like the forest floor, that soil is full of critters, like snails, and earthworms,

  • and even moisture-loving salamanders.

  • What are you doing all the way up there, little buddies?!

  • So, these treetops are a happenin' place.

  • And now that scientists actually know what's going on up there,

  • they can work on protecting these systems and all of the diversity that they support.

  • For instance, they now know that it's not enough to protect young redwood forests,

  • since they don't have these complex canopies that these old-growth forests have.

  • But dwindling numbers of redwoods have isolated some of these canopy ecosystems,

  • so scientists have begun looking at ways to speed up canopy growth

  • in younger trees to help keep this incredible ecosystem alive.

  • There are lots of incredible ocean ecosystems,

  • but the ocean floor is home to one especially unique one: whale carcasses.

  • You might think of whales washing up to the shore when they die,

  • but most of the time, dead whales actually sink,

  • dropping all the way to the bottom of the ocean floor.

  • These are called whale falls,

  • and these dead bodies become incredible hotspots for underwater life.

  • We've actually found very few of these in nature because

  • the ocean is so massive and so deep that it's pretty hard to look for things on the bottom.

  • Like, in 2013, scientists discovered a whale fall more than 4000 meters deep in the Atlantic ocean.

  • And that was only the seventh natural whale fall they'd ever studied in detail.

  • So other times, scientists have intentionally dropped carcasses into the ocean

  • in order to better understand the ecosystems that develop around them.

  • And what's amazing about whale falls is that

  • they create an ecosystem in a place where, otherwise, not much can survive.

  • There aren't many nutrients at the bottom of the ocean floor,

  • but when a whale dies, literal tons of food arrive all at once.

  • And that attracts a huge diversity of creatures!

  • Scientists have spotted animals like deep-sea octopuses,

  • crabs, snails, limpets, and even bone-eating worms.

  • They've even seen animals that they have never recorded anywhere else.

  • On one whale carcass, the majority of the 41 species researchers identified

  • were totally new to scientists.

  • These are exciting places to study marine life because

  • we actually don't know a lot about what goes on undersea.

  • I mean, only about ten percent of the ocean has even been mapped so far.

  • So whale falls are kind of like a microcosm of life in the deep sea,

  • and they give scientists a rare chance to discover and learn about the species that thrive there.

  • Apart from whale carcasses, there's also another place in the deep sea

  • that hosts a totally different kind of ecosystem;

  • one of the most chemically and physically extreme ecosystems on Earth.

  • These are fissures in the ocean crust called hydrothermal vents,

  • where blistering-hot water full of minerals bubbles out of Earth's crust.

  • And as unfriendly a place as it seems, lots of life has evolved to survive here.

  • Since there's no sunlight that deep in the ocean, photosynthesis is a no-go.

  • Luckily, these vents release a slurry of chemical compounds

  • including sulfide, hydrogen, and methane,

  • which these organisms can use in a process called chemosynthesis.

  • Basically, instead of using energy from the sun

  • to convert carbon from the environment into organic compounds,

  • organisms at these vents create organic compounds using energy from chemical reactions.

  • Which is pretty incredible!

  • But it's not just extreme microbial life living it up at these vents;

  • their energy gets transferred up the food chain.

  • Even though temperatures can reach more than 350 degrees Celsius,

  • yes, that's more than 3 times the boiling point of water,

  • because the pressure is so great that is doesn't boil,

  • the structures that form at these vents host creatures

  • like giant tubeworms, mussels, clams, crabs, and shrimp.

  • And now scientists are realizing that ecosystems at hydrothermal vents may actually have a

  • really wide influence on the rest of the planet.

  • These organisms consume the vast majority of the methane from these vents,

  • preventing this powerful greenhouse gas from being released into the atmosphere,

  • which would have an enormous effect on the Earth's climate.

  • These vents also release iron, which helps fuel the growth of phytoplankton,

  • small organisms that play a big role in capturing carbon in the ocean.

  • Aside from that, these hydrothermal vents

  • might also help us understand some of our planet's earliest life,

  • since they've existed ever since liquid water first accumulated on Earth.

  • In fact, scientists have found traces of organisms from almost 4.3 billion years ago

  • that lived at hydrothermal vents in the ancient seafloor.

  • So by studying the inhabitants of modern vents,

  • we might gain insight into the Earth's earliest microbial communities.

  • Now, you might not think of a giant hunk of ice floating through frigid waters

  • as a great place to live, but for many creatures, an iceberg is a floating oasis.

  • As icebergs float through water, even really icy water, they are always melting,

  • at least a little bit, creating a pool of freshwater that surrounds the iceberg.

  • And as they melt, they release the dust and minerals

  • that were frozen up in the iceberg, which are a good source of iron.

  • The iron in that meltwater helps fuel photosynthesis,

  • which stimulates the growth of phytoplankton around the icebergs,

  • including some species of phytoplankton that normally live in freshwater.

  • And even though icebergs are relatively small,

  • they can have a pretty wide-reaching effect on the region around them.

  • That's because it can take over a year for a big iceberg to completely melt,

  • so it can cover a lot of ground in that time and spread its minerals far and wide.

  • In a study of giant icebergs between 2003 and 2013,

  • researchers found a significant boost in chlorophyll production

  • in the 500 kilometers surrounding the iceberg,

  • and sometimes as much as a thousand kilometers away.

  • These phytoplankton communities attract all sorts of other organisms

  • to the area around the iceberg, including fish, krill, jellyfish, and seabirds.

  • Not only do they form the basis of this floating ecosystem,

  • but phytoplankton also absorb carbon in the ocean.

  • So understanding how icebergs are connected with these organisms can help us

  • understand and predict the ways that climate change will affect our oceans,

  • as more icebergs break off and enter the open sea.

  • Although there are many extreme environments in nature,

  • not all ecosystems have natural origins.

  • And one of the most unusual ecosystems on Earth

  • is the result of a human-caused catastrophe back in 1986.

  • That year, an explosion at the Chernobyl nuclear power plant released

  • huge amounts of radioactive material across 200 thousand square kilometers in Europe.

  • It was one of the worst environmental disasters in human history,

  • and humans have been evacuated from the

  • 4,000 square kilometers around the power plant for more than 30 years.

  • This is called the Chernobyl Exclusion Zone, and it is still unsafe for humans to live there.

  • Still, as deadly as the region is, some species actually seem to be thriving inside it.

  • Things haven't gone exactly back to normal.

  • Even this long after the disaster, mutation rates in animals and plants are really high.

  • Research has also shown that radiation exposure has shrunken the brains

  • of some birds and caused a rise in tumors, fertility issues, and other abnormalities.

  • Parasites may also be using these weaknesses to find new ways to attack their hosts.

  • So in general, all the major animal groups studied within the Exclusion Zone have declined,

  • including bees, grasshoppers, birds, spiders, and mammals.

  • But in spite of all that, some animals are doing better than you'd think.

  • Some species of birds seem to have responded to high radiation levels by

  • producing higher levels of antioxidants, which help reduce the damage to their DNA.

  • Weirdly enough, the birds' ability to adapt seems to be tied to their pigmentation;

  • flashier-looking birds seem less able to produce

  • enough antioxidants to protect themselves from the radiation.

  • But it's not just dull birds and parasites

  • that are able to survive under these conditions.

  • Some mammal species are actually more abundant

  • inside the exclusion zone than they are outside.

  • Scavengers, like wolves and Eurasian otters, seem to be diverse and thriving.

  • And as bizarre as that might sound, the explanation is likely pretty simple:

  • For some organisms, a radioactive ecosystem

  • is better for survival than one that has humans in it,

  • thanks to the added stress that our presence tends to put on environments.

  • Even though these radioactive or far-flung ecosystems

  • might not seem especially homey to us,

  • they go to show that life can make a home out of just about anything.

  • Understanding these ecosystems can help us protect or repair them,

  • and it can also help us appreciate how incredibly resilient and creative living things can be.

  • Thank you for watching this episode of SciShow!

  • And if you liked this video, you might enjoy our episode

  • about the tiny ecosystems hiding inside glaciers.

  • Which just goes to show that life will find a way anywhere if you give it a chance.

  • If you wanna watch that episode, you can right after this.

  • [♪ OUTRO]

[♪ INTRO]

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5個在最不可能出現的地方蓬勃發展的生態系統 (5 Ecosystems Thriving in the Least Likely Places)

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    林宜悉 發佈於 2021 年 01 月 14 日
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