Question

describe two ways to protect the biodiversity of local fresh water ecosystems

Answer 1

- Let nature take care of it
- Kill any human that could interfere !

Answer 2

Well unfortunately people do tend to live near and interact with water sources, as much as a hinderance it is to the environment (lol nathaneal).

Often freshwater ecosystems are reliant upon plant matter and other things falling into them that are associated with (you guessed it) plants growing next to the water.. so planting plants helps. (For more information try searching riparian buffer - riparian meaning riverside).

Another way is to try and prevent the flow of nutrients, often from fertilizers. This can be achieved through changing soils and usages - its probably a good idea to think about some things that are useful in your area.