Bloomin' Algae!

based on 15 ratings
Author: Sarah Benton

Grade Level: 6th - 8th; Type: Ecology, Chemistry


This project models a real world scenario and ecological issue: eutrophication, which results in bodies of water that are depleted of oxygen and are in a sense “dead”. The goal of the project is that the student becomes aware of a real ecological issue and how humans can inadvertently create damage to the natural environment. The student will also research and understand the far reaching effects of this issue and how we can work to prevent it.

Research Questions:

  • What is eutrophication?
  • What is an algal bloom and what are the environmental effects of an algal bloom?
  • What are examples of point source pollution and non-point source pollution?
  • How do fertilizers, phosphates, nitrates, etc. lead to oxygen depletion in the water?
  • What are the long term effects of a body of water being depleted of oxygen?
  • What is the experimental control in your experiment? What are some of the variables to consider in your project?

Eutrophication occurs when extra nutrients are added to a body of water. The algae or plant life in the body of water grows at a very fast rate or “blooms”. As the plants grow they begin to deplete the oxygen dissolved in the water. The other living things in the water requiring this oxygen begin to die off. Eventually the body of water cannot sustain life and it becomes a “dead” body of water. Eutrophication is mainly caused by fertilizer runoff from intensive farming practices, and improper sewage treatment. As the need for food rises with the country’s population we become dependent on farming practices different than those that have been traditionally used. This includes using more fertilizer on our crops to increase production. Chemical fertilizers are full of soluble phosphates and nitrates that run off of the land during heavy rains and irrigation. The chemicals make their way into bodies of water where they cause algal and plant blooms, hence eutrophication. When sewage runs into waterways the decomposers in the waste use the oxygen in the water and this also leads to eutrophication. In order to prevent this from happening we need to be more careful about what we use to fertilize crops and how we handle our sewage. Natural fertilizers like manure decompose more slowly so that the nutrients are not washed away quickly in run off water like the chemical fertilizers. We need to treat sewage properly before it makes its way back into the water cycle.


The materials for this project can be found at the grocery store, an aquarium supply shop and around the home.

  • 7 jars
  • Cheesecloth
  • Rubber bands
  • Masking tape
  • Pond water (pond water is best, but if it is not available water from a slow moving stream, or a lake should work as well)
  • Spring Water (bottled water)
  • Measuring cups and spoons
  • Dissolved oxygen kit (from aquarium shop)
  • Fertilizer (powdered or granulated, like Miracle Gro)
  • Powder Detergent containing phosphates (like Cascade)
  • Rubber gloves
  • Camera (optional)
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