You are studying runoff from fertilized fields that carries nutrients, such as nitrogen and phosphorus, to lakes in your area. you notice that runoff stimulates such an excessive growth of algae that its natural community interactions are disrupted. you can easily account for nutrients necessary to stimulate algal growth, but where do they get their energy?

They get energy from sunlight

Explanation:

Algae are autotrophs as they have green colored pigment called chlorophyll which helps in the process known as photosynthesis.

With the help of sunlight, carbon dioxide and other nutrients available in water aids in photosynthesis.

This process provides energy to algae for its growth and metabolism. As producers an make their own food they are dependent on photosynthesis for their energy.