Determining the Health of an Aquatic Ecosystem

Nutrients in the soil may enter groundwater and eventually move into water bodies. In aquatic ecosystems (streams, lakes, rivers, and coastal waters), nitrogen and phosphorus support the growth of water plants and algae, which in turn provide food and habitat for fish and other animals.

The graphs show how the increasing amount of nitrogen or phosphorus affects algae growing in a lake.

In addition to the amount of nutrients, other factors can affect the health of the ecosystem. The amount of dissolved oxygen, soil, and other small particles in the water, and the presence of E. coli bacteria all help indicate how healthy a body of water is.

What is the relationship between the amount of nitrogen or phosphorus and algae growth? Support your answer with evidence.