Have you ever heard the sound of frogs calling at night?
你有听过青蛙在夜晚的鸣叫吗？
For hundreds of millions of years, this croaking lullaby has filled the nighttime air.
几亿年来，这由呱呱声组成的催眠曲一直与夜晚的宁静相随。
But recent studies suggest that these frogs are in danger of playing their final note.
但是近期的研究显示，这些青蛙正处于危险之中，它们的鸣叫将会成为绝唱。
Over the past few decades, amphibian populations have been rapidly disappearing worldwide.
在过去几十年间，在全世界范围内，两栖类动物的数量一直在快速减少。
Nearly one-third of the world's amphibian species are endanger of extinction,
将近1/3的两栖类物种都面临灭绝的危险，
and over 100 species have already disappeared.
上百个物种已经消失了。
But don't worry, there's still hope.
所幸的是，希望还在。
Before we get into how to save the frogs,
在谈论如何拯救青蛙之前，
let's start by taking a look at why they're disappearing and why it's important to keep them around.
让我们先看看它们消失的原因和保护它们的重要性。
Habitat destruction is the number one problem for frog populations around the world.
栖息地遭到破坏是首要问题，对遍布世界各地的青蛙都是如此。
There are seven billion humans on the planet, and we compete with frogs for habitat.
地球上居住着70亿人口，我们与青蛙争夺着栖息地。
We build cities, suburbs, and farms on top of frog habitat
我们在青蛙的栖息地上建设城市，郊区，开辟农场，
and chop forests and drain the wetlands that serve as home for numerous amphibian populations.
砍伐森林，把为无数两栖动物提供了庇护的湿地消耗殆尽。
Climate change alters precipitation levels, drying up ponds, streams, and cloud forests.
气候变化改变了降雨量，使池塘和河流干枯，雾林枯竭。
As the Earth's human population continues to grow, so will the threats amphibians face.
随着地球上人口数量的增加，两栖类动物面临的威胁也随之增长。
There are a variety of other factors contributing to the frogs' decline.
有各种各样其它的原因导致青蛙数量减少。
Over-harvesting for the pet and food trade results in millions of frogs being taken out of the wild each year.
为发展宠物和食物交易进行的过度捕捉，使上百万的青蛙每年于荒野中消失。
Invasive species, such as non-native trout and crawfish, eat native frogs.
入侵物种，比如鳟鱼和小龙虾，都会吃掉本地的青蛙。

Humans are facilitating the spread of infectious diseases
人类正在加快传染性疾病的传播，
by shipping over 100 million amphibians around the world each year for use as food, pets, bait,
通过每年在全球范围内用船运输上亿只两栖动物，供我们当作食物，宠物，诱饵，
and in laboratories and zoos, with few regulations or quarantines.
或被送进实验室和动物园，没有法规约束或进行检疫。

One of these diseases, chytridiomycosis,
在这些疾病当中，壶菌病，
has driven stream-dwelling amphibian populations to extinction in Africa, Australia, Europe, and North, Central, and South America.
已把沿河居住的两栖动物逼入绝境，包括非洲，澳大利亚，欧洲和美国的北部、中部、南部。
On top of all these problems, we add hundreds of millions of kilograms of pesticides to our ecosystems each year.
除了这些问题之外，我们每年还往生态系统中喷洒上亿公斤的农药。
And these chemicals are easily absorbed through amphibians' permeable skin,
这些化学物质可轻易通过两栖动物可渗透性的皮肤被吸收，
causing immunosuppression, or a weakened immune system, and developmental deformities.
导致其免疫低下或削弱免疫系统，从而导致畸形。
Okay, so why are these little green guys worth keeping around?
那么为什么我们周围的世界里非要有这些绿色的小东西呢？
Frogs are important for a multitude of reasons.
青蛙的重要性有诸多体现。
They're an integral part of the food web, eating flies, ticks, mosquitoes, and other disease vectors,
它们是食物网不可分割的一部分，它们捕食苍蝇，虱子，蚊子和其它疾病媒介物
thus, protecting us against malaria, dengue fever, and other illnesses.
这使得我们免于遭受疟疾，登革热和其它疾病带来的痛苦。
Tadpoles keep waterways clean by feeding on algae,
蝌蚪吃掉藻类，保持水道的清洁，
reducing the demand on our community's filtration systems and keeping our cost of water low.
降低我们的社区对过滤系统的要求，维持饮用水的成本在较低水平。
Frogs serve as a source of food for birds, fish, snakes, dragonflies, and even monkeys.
青蛙是包括鸟，鱼，蛇，蜻蜓，甚至猴子在内的很多动物的食物来源。
When frogs disappear, the food web is disturbed, and other animals can disappear as well.
当青蛙消失，食物网就会被打乱，其它动物也会消失。
Amphibians are also extremely important in human medicine.
两栖动物在人类药物学方面也功不可没。
Over ten percent of the Nobel prizes in physiology and medicine have gone to researchers whose work depended on amphibians.
诺贝尔生理学奖和医学奖的得主中，超过百分之十的人在研究过程中需要用到两栖动物。
Some of the antimicrobial peptides on frog skin can kill HIV,
青蛙皮肤上的一些抗菌肽可以杀死艾滋病病毒，
some act as pain killers, and others serve as natural mosquito repellents.
一些可以作为止痛药，其它一些可以作为天然的驱蚊剂。
Many discoveries await us if we can save the frogs,
如果我们能拯救青蛙，还有许多未知等待我们去探索，
but when a frog species disappears, so does any promise it holds for improving human health.
但当一个青蛙物种灭绝时，它承载的改善人类健康的希望便也随之破灭了。
Fortunately, there are lots of ways you can help,
幸运的是，你可以通过很多方式提供帮助，
and the best place to start is by improving your ecological footprint and day-to-day actions.
最好的出发点就是增加你的生态足迹和日常行动。
The next time you listen to that nighttime lullaby,
下次你再听到那夜之催眠曲时，
don't think of it as just another background noise, hear it as a call for help, sung in perfect croaking harmony.
别再只把它当成另一种背景噪音了，把它当作是用“呱呱”这样悦耳的音符来呼救吧。