Attack of the killer algae - Eric Noel Muñoz

412,383 views ・ 2014-06-24

TED-Ed


Please double-click on the English subtitles below to play the video.

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We've all seen the movies where a monster,
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created by a scientist in a laboratory,
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escapes to wreak havoc on the outside world.
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But what if the monster was not some giant rampaging beast,
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destroying a city, but just a tiny amount of seaweed
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with the potential to disrupt entire coastal ecosystems?
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This is the story of Caulerpa taxifolia,
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originally a naturally occurring seaweed
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native to tropical waters.
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In the 1980s, one strain was found to thrive in colder environments.
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This trait, combined with its beautiful, bright green color
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and ability to grow quickly without maintenance
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made it ideal for aquariums, which it helped keep clean
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by consuming nutrients and chemicals in the water.
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Further selective breeding made it even heartier,
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and soon it was used in aquariums around the world.
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But it was not long before a sample of this
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aquarium-developed super algae
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turned up in the Mediterranean Sea
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near the famed Oceanographic Museum of Monaco.
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The marine biologist who found it believed that
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the museum had accidentally realeased it into the ocean
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along with aquarium waters,
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while museum directors claimed
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it had be carried into the area by ocean currents.
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Regardless of how it ended up there,
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the non-native Caulerpa multiplied rapidly,
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having no natural predators
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due to releasing a toxin that keeps fish away.
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And like some mythical monster, even a tiny piece that broke off
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could grow into a whole new colony.
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Through water currents and contact with boat anchors and fishing lines,
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it fragmented and spread throughout Mediterranean coastal cities
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covering coral reefs.
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So what was the result of this invasion?
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Well, it depends on who you ask.
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Many scientists warned that the spread of Caulerpa
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reduces biodiversity by crowding out native species of seaweed
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that are eaten by fish,
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with the biologist who first discovered its presence dubbing it
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Killer Algae.
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Other studies instead claim
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that the algae actually had a beneficial effect
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by consuming chemical pollutants --
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one reason the aquariums strain was developed.
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But the disruption of a natural ecosystem
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by an introduced foreign species
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can have unpredictable and uncontrollable effects
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that may not be immediately visible.
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So when Culerpa taxifolia was discovered
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at Carlsbad's Agua Hedionda Lagoon,
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near San Diego in the year 2000,
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having most likely come from the dumping
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of home aquarium water into a connecting storm drain,
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it was decided to stop it before it spread.
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Tarps were placed over the Culerpa colonies
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and chlorine injected inside.
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Although this method killed
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all other marine life trapped under the tarps,
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it did succeed in eradicating the algae
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and native eelgrass was able to emerge in its place.
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By responding quickly, authorities in California
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were able to prevent Culerpa from propagating.
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But another occurrence of the strain,
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in the coastal wetlands of southeast Australia,
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was left unchecked and allowed to spread.
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And unfortunately, a tarp cannot cover the Mediterranean Sea
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or the Australian coast.
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Invasive species are not a new problem,
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and can indeed occur naturally.
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But when such species are the results of
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human directed selective breeding or genetic modification
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and then released into the natural environment,
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their effect on ecosystems
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can be far more radical and irreversible.
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With the proliferation of new technologies
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and multiple threats to the environment,
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it is more important than ever for scientists
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to monitor and evaluate the risks and dangers,
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and for the rest of us to remember
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that what starts in our backyard
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can effect ecosystems half a world away.
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