Oxygen Levels in Fish Raceways

Data from fish raceways show changes in oxygen levels as the water passes through raceways containing large fish populations and over weirs that aerate the water. 

Possible Guiding, Compelling and/or Anchoring Questions

What does the graph show? 
What is happening to cause the values to change?

Classroom Suggestions

• Carrying Capacity: The amount of fish that can be effectively raised depends upon sufficient oxygen levels in the water, so stocking rates are adjusted to match the dissolved oxygen (DO) available. Young, fast growing fish require higher DO levels than older fish. 
• The bacteria that feed on feces and algae also alter the DO used in the raceway.
• Adaptations to Habitat: Trout have high oxygen needs and thrive in cold, fast moving streams.
• Additional Questions:
  • Why is supplemental oxygen needed in modern aquaculture?
  • How does pressure affect dissolved oxygen levels?
  • Why is water temperature important?
  • How does Le Chatelier’s Principle help us to make predictions?
  • How do weirs work? What are their limitations?
  • What is gas bubble disease, how is it prevented, and how is it tied to human health?
     

Related Resources

• Le Chatelier’s Principle: Comprehensive article on equilibrium with links to other resources and example graphs showing effects of changes.  
• PhET: Reversible Reactions Simulation: Several teaching activities available with a free account, simulation of shifts, runs on CheerpJ.
• Professor Dave Explains: Gives examples of Le Chatelier’s Principle, with a quick quiz at the end.
• Equilibrium: Crash Course Chemistry #28: Explains the basics of equilibrium.