What is a trophic cascade, and how can protecting whales prevent climate change? Huh? What? But if you have watched the video above, you understand what a trophic cascade is now. It is much better to learn by examples than by a crazy difficult definition like the one below…
Trophic cascades occur when predators in a food web suppress the abundance or alter the behavior of their prey, thereby releasing the next lower trophic level from predation (Wikipedia)
Here are some key language functions/discourse markers used in the video which could be used in IELTS speaking. Some of them are too informal for an essay. I have added some more formal written equivalents for you to match them to.
Match the spoken phrases from the video with the more formal, written ones.
From the video (Spoken English)
1. We all know that (at 0.50 in the video)
2. Not only… , but also (1.18)
3. It now turns out that… (1.15)
4. But the story doesn’t end there (2.58)
5. The more X, the more Y. (3.24) also: More X, means more Y.
In an essay (more formal)
A. It has now become evident that…
B. Furthermore, …
C. Not only…, but in addition…
D. It is widely known that…
E. Increased levels of X cause corresponding rises in Y.
These two phrases should be guessable from the video, and I’ve marked the times on them for you to look them up.
- Pitch dark (1.31)
- It seems counter intuitive (1.10)
A few more difficult words from the video:
To sink into the abyss
To sink…
- A boat sinks when it fills with water.
- Your heart sinks when you hear bad news.
Abyss is a large, deep and dark place; where there is no light at the bottom of the sea.
It now turns out that
- We have now discovered that…
- We have now realised that…
Boosts
- Helpfully increases
Speaking Practice
Answer the following IELTS part 2 question about whales or another animal species:
Describe an animal you think is important to protect
You should say:
- What the animal is
- Where it lives
- Why it needs to be protected
Explain how you feel about this animal
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