Algae Abundance in F.W. Kent Lake

The amount of filamentous and periphytic algae (growing on plants) over a four-week period was visibly reduced after an early summer bloom, as shown in the before and after footage. Phosphate and dissolved oxygen levels that were recorded during the phenomenon suggest that algae began dying off and decomposing.

Driving Question

• What is causing the algae abundance in lakes to change over time?

Probing Questions

• What populations would you expect to find in a healthy lake and what resources do these populations need?
• How does an abundance of algae affect a lake?
• Why do you think this lake experienced a brief algae bloom, but was not overtaken by the algae?
• What could people do to manage and control algae blooms?

Classroom Suggestions

Students could: 

• Investigate the data table to identify patterns in the data that would correlate to the growth and decline of the algae observed.
• Visit a local body of water periodically from late summer into fall to observe and document what species are present and how their populations change over time. Chemical water quality assessments (pH, dissolved oxygen, nitrate/nitrite, phosphate, chloride) as well as physical (e.g. turbidity) assessments can be collected and compared.
• Learn from an expert. Invite a resource management specialist from your county to share what work has been done or needs to be done to improve the water quality in your local bodies of water.
• Research limiting factors, including phosphorous, that affect producer populations, particularly algae. What might cause changes to the levels of these factors? How have humans tried to control these factors?

Relevant Related Resources

• From Farms to Phytoplankton: Lesson plan on eutrophication for secondary students.
• What is Eutrophication?: Video overview of eutrophication from NOAA with transcript and links.
• USGS Water-Resources Investigations Report: USGS report on phosphorus control measures for water quality.
• Iowa's Waters: Links relating to Iowa’s water resources from Iowa Conservation Education Coalition.