Jeremy Jackson : How we wrecked the ocean

Jeremy Jackson at Mission Blue Voyage  (transcript)
How we wrecked the ocean
Summary
In the article, the speaker explains important ecological systems of our oceans to understand really well.
For beautiful coral reefs, no fish is important. 1)
However, overfishing leads to dying sea urchin because fish that big fish eat had been caught by people. 2)
The seaweed can grow immediately because sea urchin that eats seaweeds dies. 3)
There is no fish, though, there is a lot of seaweed and slams.  4)
And then, overfishing, pollution, and climate change prevent sea recovering. 5)

However, the answers about how we wrecked the ocean are not those.
The answer is that we, people, are continually doing. It's our greed, need for growth, and selfishness. Ocean recovering depends on us.

Words in the story
urchin /ˈɚːtʃɪn/