Algae in Excess

Plants need nutrients to grow. This is why we apply fertilizers to grass and food crops. In this activity, learners will explore how fertilizers can affect lakes and other bodies of water. Learners will first have to collect a sample of algae from a pond, lake, or stream. Using these samples. Learners will then examine the effects of fertilizer and fish food on the algae over two weeks. Step-by-step instructions are included with photos along with safety recommendations. Activity guide includes a “What’s going on?” explanation and relevant connections to the effects of algae growth and death on rivers and lakes.

Materials List:

• 3 clear containers, such as jars or plastic bottles, approximately 500mL (2 c) each


• Access to a pond, lake or stream with algae


• Liquid fertilizer used for lawns or house plants


• Masking tape


• Marker


• Disposable gloves


• One or more drinking straws (optional)


• Fish food (optional)