Why are frogs disappearing? - Kerry M. Kriger

391,326 views ・ 2013-09-16

TED-Ed


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

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Have you ever heard the sound of frogs
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calling at night?
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For hundreds of millions of years,
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this croaking lullaby has filled the nighttime air.
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But recent studies suggest
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that these frogs are in danger
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of playing their final note.
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Over the past few decades,
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amphibian populations have been rapidly disappearing worldwide.
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Nearly one-third of the world's amphibian species
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are endanger of extinction,
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and over 100 species have already disappeared.
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But don't worry, there's still hope.
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Before we get into how to save the frogs,
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let's start by taking a look
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at why they're disappearing
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and why it's important to keep them around.
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Habitat destruction is the number one problem
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for frog populations around the world.
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There are seven billion humans on the planet,
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and we compete with frogs for habitat.
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We build cities, suburbs, and farms
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on top of frog habitat
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and chop forests
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and drain the wetlands
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that serve as home
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for numerous amphibian populations.
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Climate change alters precipitation levels,
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drying up ponds, streams, and cloud forests.
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As the Earth's human population continues to grow,
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so will the threats amphibians face.
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There are a variety of other factors
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contributing to the frogs' decline.
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Over-harvesting for the pet and food trade
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results in millions of frogs
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being taken out of the wild each year.
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Invasive species,
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such as non-native trout and crawfish,
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eat native frogs.
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Humans are facilitating the spread
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of infectious diseases
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by shipping over 100 million amphibians
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around the world each year
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for use as food, pets, bait,
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and in laboratories and zoos,
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with few regulations or quarantines.
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One of these diseases,
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chytridiomycosis,
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has driven stream-dwelling amphibian populations
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to extinction
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in Africa,
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Australia,
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Europe,
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and North, Central, and South America.
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On top of all these problems,
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we add hundreds of millions of kilograms of pesticides
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to our ecosystems each year.
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And these chemicals are easily absorbed
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through amphibians' permeable skin,
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causing immunosuppression,
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or a weakened immune system,
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and developmental deformities.
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Okay, so why are these little green guys
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worth keeping around?
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Frogs are important for a multitude of reasons.
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They're an integral part of the food web,
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eating flies, ticks, mosquitoes,
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and other disease vectors,
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thus, protecting us against malaria,
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dengue fever,
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and other illnesses.
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Tadpoles keep waterways clean
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by feeding on algae,
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reducing the demand
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on our community's filtration systems
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and keeping our cost of water low.
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Frogs serve as a source of food
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for birds, fish, snakes, dragonflies, and even monkeys.
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When frogs disappear,
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the food web is disturbed,
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and other animals can disappear as well.
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Amphibians are also extremely important
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in human medicine.
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Over ten percent of the Nobel prizes
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in physiology and medicine
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have gone to researchers
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whose work depended on amphibians.
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Some of the antimicrobial peptides
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on frog skin can kill HIV,
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some act as pain killers,
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and others serve as natural mosquito repellents.
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Many discoveries await us
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if we can save the frogs,
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but when a frog species disappears,
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so does any promise it holds
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for improving human health.
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Fortunately, there are lots of ways you can help,
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and the best place to start
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is by improving your ecological footprint
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and day-to-day actions.
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The next time you listen to that nighttime lullaby,
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don't think of it as just another background noise,
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hear it as a call for help,
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sung in perfect croaking harmony.
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