This short, targeted simulation is adapted from the full-length “Marine Biology” simulation.

Can you get to the bottom of a mysterious massive fish-killing?  In this simulation, you will be an environmental investigator to solve this fish kill mystery. You will analyse the oxygen levels in the water using a spectrophotometer and discover the impact of the oxygen levels on the fish.

The mass fish-killing

Meet Trisha at the bay where you learn of a mass fish killing. Make a hypothesis about what happened and discuss how you could find the cause of the fish killing. Take samples from the site of the fish killing before returning to the lab.

Analyze the oxygen levels in water

You collected water samples from the bay where the fish were found. Start your analysis by learning about the principles of spectrophotometry. To measure the absorbance of your samples you need to add a coloring agent that has more intense color if more oxygen is in the sample. Use a spectrophotometer to measure the absorbance of the water sample and samples containing a known amount of oxygen. Plot a calibration curve to compare the dissolved oxygen levels in the water sample to the known value samples to investigate whether low oxygen in the lake could have caused the massive fish death. Do the results of this analysis correspond with the symptoms exhibited by the fish?

Solve the mystery

After gathering evidence by analysing the dissolved oxygen levels in the water samples, you will need to figure out what caused the massive fish death. Will you be able to solve the mystery?