Lesson Plan #9 – Algal Bloom Research



Students will understand that human choices greatly affect our natural waterways by observing what chemicals do to phytoplankton and other types of algae.


An algal bloom is a build up of usually microscopic algae growing out of control in a body of water. Algal blooms may occur in fresh or salt water and can grow to be millions of cells per milliliter of water. Algal blooms are often green, but depending on the specific species of algae can also may be other colors such as yellow, red or brown. Some algal blooms are actually caused by Cyanobacteria, which are not actually considered to be algae. Some kinds of algal blooms, such as red tides can also be poisonous which often effects our ability to eat shellfish. Algal blooms are often caused by nutrients such as fertilizer or Nitrogen / Phosphorus run off from farms or cities. Large storms can often flush massive amounts of nutrients into our water ways causing algal blooms to grow out of control. When an algal bloom occurs, the algae use up all the oxygen and cause it to be hypoxic which means that it’s low in oxygen. Life can not exist in water without balanced levels of nutrients and oxygen, so when this happens all life in the water dies and it becomes known as a “dead zone”.


How do phytoplankton react to the imbalance of nutrients in the water?

What are the long term effects of our choices and the health of the marine food web?

What actions can humans take to educate other people about this problem?

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