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Decoding Diatoms: Paleo to Present Day Water Studies

Submitted By: Victoria Chraibi (Fulbright Eco-Leadership Program), Alexis Berke and Sarah Erickson (Great Lakes Aquarium) and Nadine Meyer (Minnesota DNR MinnAqua Program)
Age Range: Grades 7-12
Time Needed: 1-3 hours for activity, additional prep time

Materials Needed:

Main Learning Objectives: To understand the use of diatoms as a tool for studying the health of a lake over time. Students will view and identify microorganisms found in freshwater and will identify diatoms found in pond water samples. Download the full lesson plan for a list of MN state science objectives met by this activity. (Lesson Plan)

Description of Activity:Summary: Diatoms are a type of algae. Their cell walls are made of silica (glass.) This unique structure preserves their shape, and makes them excellent species to study the condition of lakes over time. Scientists can collect core samples and identify diatoms in the layers of that sediment core that were living at various points in time. The presence or absence of certain diatoms can help us understand the history of the particular lake. Diatoms are ubiquitous and are found in most water. In this lesson, students will practice microorganism identification using local water samples and apply this understanding to a study of diatoms found in Lake George. Topic: Freshwater microorganisms, specifically diatoms Theme: The presence or absence of diatoms in a core samples from a lake bed, can give clues to changing lake conditions over time.

Diatom Activity