1. Influence of water’s chemical properties on aquatic organisms
There are several chemical properties that can affect organisms, including the pH of water, and the salinity of water.

2. pH levels and how the affect organisms
The level of pH in the water either makes the water more acidic or basic. This can cause a problem to organisms because they need to maintain a certain pH level
A factor of pH levels is carbon dioxide. If there is a decrease in this then the water becomes more basic while an increase causes the water to be more acidic.

3. Dissolved oxygen
The amount of oxygen in the water also determines where an organism can live. An example is a fish that requires more oxygen will live in a fast moving stream while another fish might not require the same amount of oxygen and lives in a lake or a pond.
The faster the water moves the more oxygen it is going to have, but a lake does not have fast moving water so it has very little oxygen in it.

4. Salinity
The salinity of water is also a key chemical factor that determines where a certain organism lives. Some species require salt being in the water to survive while others do not require any at all.

5. Influence of waters physical properties on aquatic organisms
There are two main physical points of water that can determine where an organism lives and that’s how cold or warm the water is and how fast the water is moving.

6. Physical properties of water
How warm or cold water is is determined by how fast a stream moves.
A faster stream is normally colder and only certain organisms live.
A slower moving stream, lake, or pond is normally warmer and only certain organisms live there.
A trout normally lives in fast moving cold streams
A bluegill many lives in warm slow moving lakes.

7. Influence of the surrounding land on organisms
Some things that can affect a stream are trees and different land areas, for example cliffs and hills.

8. Trees
Trees affect a stream and its organisms by providing shade making the water cooler and also organic material which is the basis to maintaining this ecosystem.

9. Land formations
Land formations also affect organisms by making the water flow faster or change completely

10. The water cycle and how it affects aquatic ecosystems
Drought can really affect and ecosystem including other organisms besides aquatic organisms.
Flooding can also change an ecosystem by making the water foggy and providing food for the organisms.
Pollution can kill and affect many organisms in this ecosystem