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  • We've all seen the movies where a monster,

  • created by a scientist in a laboratory,

  • escapes to wreak havoc on the outside world.

  • But what if the monster was not some giant rampaging beast,

  • destroying a city, but just a tiny amount of seaweed

  • with the potential to disrupt entire coastal ecosystems?

  • This is the story of Caulerpa taxifolia,

  • originally a naturally occurring seaweed

  • native to tropical waters.

  • In the 1980s, one strain was found to thrive in colder environments.

  • This trait, combined with its beautiful, bright green color

  • and ability to grow quickly without maintenance

  • made it ideal for aquariums, which it helped keep clean

  • by consuming nutrients and chemicals in the water.

  • Further selective breeding made it even heartier,

  • and soon it was used in aquariums around the world.

  • But it was not long before a sample of this

  • aquarium-developed super algae

  • turned up in the Mediterranean Sea

  • near the famed Oceanographic Museum of Monaco.

  • The marine biologist who found it believed that

  • the museum had accidentally realeased it into the ocean

  • along with aquarium waters,

  • while museum directors claimed

  • it had be carried into the area by ocean currents.

  • Regardless of how it ended up there,

  • the non-native Caulerpa multiplied rapidly,

  • having no natural predators

  • due to releasing a toxin that keeps fish away.

  • And like some mythical monster, even a tiny piece that broke off

  • could grow into a whole new colony.

  • Through water currents and contact with boat anchors and fishing lines,

  • it fragmented and spread throughout Mediterranean coastal cities

  • covering coral reefs.

  • So what was the result of this invasion?

  • Well, it depends on who you ask.

  • Many scientists warned that the spread of Culerpa

  • reduces biodiversity by crowding out native species of seaweed

  • that are eaten by fish,

  • with the biologist who first discovered its presence dubbing it

  • Killer Algae.

  • Other studies instead claim

  • that the algae actually had a beneficial effect

  • by consuming chemical pollutants --

  • one reason the aquariums strain was developed.

  • But the disruption of a natural ecosystem

  • by an introduced foreign species

  • can have unpredictable and uncontrollable effects

  • that may not be immediately visible.

  • So when Culerpa taxifolia was discovered

  • at Carlsbad's Agua Hedionda Lagoon,

  • near San Diego in the year 2000,

  • having most likely come from the dumping

  • of home aquarium water into a connecting storm drain,

  • it was decided to stop it before it spread.

  • Tarps were placed over the Culerpa colonies

  • and chlorine injected inside.

  • Although this method killed

  • all other marine life trapped under the tarps,

  • it did succeed in eradicating the algae

  • and native eelgrass was able to emerge in its place.

  • By responding quickly, authorities in California

  • were able to prevent Culerpa from propagating.

  • But another occurrence of the strain,

  • in the coastal wetlands of southeast Australia,

  • was left unchecked and allowed to spread.

  • And unfortunately, a tarp cannot cover the Mediterranean Sea

  • or the Australian coast.

  • Invasive species are not a new problem,

  • and can indeed occur naturally.

  • But when such species are the results of

  • human directed selective breeding or genetic modification

  • and then released into the natural environment,

  • their effect on ecosystems

  • can be far more radical and irreversible.

  • With the proliferation of new technologies

  • and multiple threats to the environment,

  • it is more important than ever for scientists

  • to monitor and evaluate the risks and dangers,

  • and for the rest of us to remember

  • that what starts in our backyard

  • can effect ecosystems half a world away.

We've all seen the movies where a monster,

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B2 US TED-Ed algae aquarium seaweed mediterranean strain

【TED-Ed】Attack of the killer algae - Eric Noel Muñoz

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    稲葉白兎 posted on 2015/01/25
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