1. Just Keep Swimmin’: Investigating Population Growth
Name: _______________________
Date: ________________________
Pd. _______
Just Keep Swimmin’: Investigating Population Growth
You will investigate what happens to the population of fish as various factors change. You will also determine how limiting factors affect population growth rates. With populations, a limiting factor is the factor that controls the growth of the population. Density-dependent factors vary according to how dense the population is. Density-independent factors, such as seasons or severe weather, affect organisms regardless of population density.
Procedure:
1. Go to the following website:
2. Work with your partner to follow the tutorial in the simulation to familiarize yourself with how the simulation works. Read each screen carefully and be sure you understand each part of the tutorial before moving to Stage 1 of the simulation.
3. In Stage 1, click on the “Show Normal Population Growth” box to see the graph of what happens to this population if reproduction, migration, and death rates are moderate.
Draw the graph here. Be sure to label the axis.
4. Explore what happens to the population as you change the three variables (Reproduction, Migration, and Death). Change one of the three variables at a time and click “Play” afterwards. Click “Reset” to start again.
Draw the resulting three graphs graph here. Be sure to label the axis.
Compare and contrast the three graphs above to the normal population growth graph.
5. Move to Stage 2, and repeat Steps 3 and 4. Note that in Stage 2 you cannot control pollution or disease events, which will occur at random intervals. Keep the default levels of predation and food. Anytime disease or pollution occur assume they are catastrophic disasters. Click “Play” and draw the resulting graph. Circle places where disease or pollution occur.
Draw the resulting graph here. Be sure to label the axis.
Compare and contrast this graph with the normal population graph.
High Reproduction Rate
High Migration Rate
High Death Rate

2. Move to Stage 3, and repeat Steps 3 through 5
Move to Stage 3, and repeat Steps 3 through 5. Choose two seasons and move them to the moderate setting, while leaving the other two the same.
6. Move to Stage 4. In this stage, all of the factors are combined. Repeat Steps 3 through 5. Keep everything at the default level, but change TWO seasons to the medium level and high reproduction. Circle where disasters occur in the graph.
Repeat step 6, but instead of high reproduction, change it to low reproduction.
Which of the factors in this simulation were density-dependent and provide some examples of density-independent factors (DISEASE IS NOT DENSITY-INDEPENDENT).
What would be some density-dependent and density-independent factors for the human population? Explain your choice.
Why do population growth graphs level off at the end? What does this value represent (think of the specific term!)? Explain.
Draw the resulting graph here. Be sure to label the axis.
Why is it important to have seasons and catch limits on fish populations?
Draw the resulting graph here. Be sure to label the axis.
Salmon experience population dynamics like the graph at right. Can salmon fishing be done sustainably? Explain your answer.
Salmon
Draw the resulting graph here. Be sure to label the axis.
Groupers are long lived fish that take up to 30 years to reach sexual maturity. Which graph most closely matches the pattern expected of grouper are fished.? What precautions should be taken when harvesting grouper?
Grouper