1. What do the presence of fish and a wide diversity of invertebrates in a river indicate

The river is very clean.

Explanation:

It indicates that the river is very clean since if you have fish and other invertebrates, you have to have some algae and water plants. If the river is dirty, little plants will grow and there won't be many fish and other invertebrates.

The river is very clean. I agree with the first response

may i see the historical information and the excerpt?

i dont know doing this for points