这篇报道的主角是大堡礁（the Great Barrier Reef）。我们传统意义上所说的珊瑚，其实只是珊瑚的骨架。而在这些骨架上，生活着数以万计的珊瑚虫，有了这些珊瑚虫，珊瑚才是色彩斑斓的。同时与珊瑚虫共生着无数的藻类。这些藻类和珊瑚虫对于水温都十分敏感，温度一旦变化，他们就很可能死去，从而造成珊瑚失去色彩，而白化问题。近期，由于全球变暖，珊瑚白化的问题越发严重，科学家们呼吁大家关注此问题，并且正在寻找解决的方案。
澳大利亚语言学院整理的PTE素材库，旨在帮助各位PTE的烤鸭们在平时练习、复习备考的阶段，除了一些官方的练习题之外，还能有不少的素材可以练习听力、阅读、口语、写作，不同PTE的题型，例如re-tell lecture，例如summarize spoken test 都是各位考生们比较纠结的难点题型。这篇文章是一篇很好的听力练习材料，包含了很多不常见的生词，所以可以用来练习Re-tell Lecture。大家可以试试看光听，不看画面的话，你能否理解polyp以及algae 到底都是什么呢？
bleach v. 漂白，变白
organism n. 有机体，生物体
chunk n. 大块
polyp n. 珊瑚虫，息肉，水螅虫
sensitive adj. 敏感的
die off 相继死去，逐个死亡
bounce v. 弹跳，反弹
combat n. 战斗，斗争
The federal Environment Minster has raised the coral bleaching threat level to its highest point. Researchers say this summer’s bleaching is the worst they’ve seen in 15 years. But how does it even happen? Here’s the answer.
This is probably how you imagine the Great Barrier Reef looks. The film Finding Nemo showed kids around the world the beautiful creatures and colours of the Reef.
But lately big parts of the reef have been looking more like this. Lots of the coral on the reef is turning white because of something known as ‘coral bleaching’.
So where have all the bright colours gone? Well, first up, let’s take a look at where all that colour actually comes from in the first place. The Great Barrier Reef is one of the great natural wonders of the world and it’s the only living organism visible from space. Yep, you heard right – that giant thing is actually alive.
CARL: See when you look at a chunk of coral, you’re actually looking at its skeleton.
But if you look a little closer, you’ll see these tiny little bumps all over it. Inside those little bumps live something called polyps, and that’s the part of the coral that’s alive when it’s still under water. And a single chunk of coral can have millions and millions of these things living together in a single colony.
Polyps spend their time popping out of their little hidey holes and munching on any food that floats past. They then convert it into more of that coral skeleton.
But the coral isn’t alone in those little holes. There are tiny little algae inside too! And they actually help feed the coral by converting sunlight into energy the coral can use! While doing that the algae also gives coral its amazing colours.
But that algae is really sensitive to temperature. If it gets too warm the algae leave, the coral turns white, and it starts to starve. If the water cools down quickly they can recover. But if it stays too warm for too long, some coral die. And that’s the problem researchers are seeing right now after some record-breaking hot months.
KATE QUIGLEY, JAMES COOK UNIVERSITY: If you just kind of look just to the side of us, right next to Carly, you can see just tons of white colonies.
These scientists are based on Lizard Island, North of Cairns and they’re worried things will just keep getting warmer and warmer up here because of climate change.
TERRY HUGHES, JAMES COOK UNIVERSITY: The reports in the last few days have been quite extreme levels of bleaching with the beginning of coral mortality.
When corals die off it’s a big problem because it can take years or even decades for it to recover, if ever. And even if it does bounce back, it might not have the same diversity of corals and colours as before.
The government says it’ll put more money into programs designed to keep an eye on the reef, and it’s raised the coral bleaching threat level to as high as it can go.
Many scientists say that’s good news, but some say we need to be doing more to combat climate change. Things like switching to more renewable energy sources instead of burning fossil fuels. Because if we aren’t careful this giant, complex colourful mass of life could be lost for good.