Open the Stella model called "daphniamed"
You will see two buttons fluoxetine and clofibric. These buttons add the medication to the water. When the medication is added the center of the button is green. Start with the buttons off (not green).
Double click on the male female graph. A graph will appear. Double click on the female table. This table records the number of female daphnia each day of the experiment. Each time you run an experiment the data is recorded in a new column.
Double click on the males table to open it up. These tables shouldn't have data in them before you start experimenting. To clear the data click the dynamite icon at the top right of the table.
There are two ways to run the experiment. You can pull down the run tab at the top of the screen and select run. The second way is to select the running man at the bottom left corner of the screen. This opens a dialog box. Clicking on its right arrow runs the model.
Run the model and see how the daphnia reproduce when there is no medication in the water.
1. Describe how the male and female populations change. What are their highest and lowest numbers.
Click on the fluoxetine button. The center should be green. This adds a small amount of the antidepressant fluoxetine to the water. Run the model again to see how the daphnia grow with this medication.
2) Describe how the male and female populations change with fluoxetine in the water. What are their highest and lowest numbers.
Click on the fluoxetine button again to remove it from the water. The fluoxetine button should be gray not green. Click on the clofibric button to add it to the water. Run the model to see how the daphnia grow with this medication.
3. Describe how the male and female populations change with clofibric in the water. What are their highest and lowest numbers.
4. Predict what will happen when you add both fluoxetine and clofibric acid to the daphnia's water.
For the last trial add both fluoxetine and clofibric to the water. Both buttons should be green. Run the model.
5. Describe how the male and female populations change with both fluoxetine and clofibric in the water. What are their highest and lowest numbers.
Copy the data from the tables to a spreadsheet. Design an algorithm to compare the control run with each of the runs with medication. (Hint; subtracting the control number from the medicated number will give the difference for each day.)
6. Describe the short and long term effect of the two medications on your daphnia.
7. Describe the effect on the daphnia with both medications in the water.
8. Would you recommend additional experiments to see if medications effect other animals in rivers and streams? Defend your recommendation.