The ecosystem of this lake is very fragile.

His actions exerted a great influence on our plans.

Due to overfishing, there is a possibility that the marine ecosystem could be destroyed.

The problem of overfishing is having a serious impact on marine ecosystems.

This problem is very serious.

Do you understand the seriousness of this problem?

His opinion had a big influence on my decision.

That news greatly influenced his opinion.

We learned about the protection of the main sea.

He is an expert in ecology.