1. Malawi: Carrying Capacity
SC.7.L.17.3
Describe and investigate various limiting factors in the local ecosystem and their impact on native populations, including food, shelter, water, space, disease, parasitism, predation, and nesting sites.

2. Engagement- Carrying Capacity Probe
Complete the Carrying Capacity and Limiting Factors Probe (page 50)

3. Exploration- The Great Table Experiment – How many is too many?
Table with :
4 chairs
15 sheets of paper
15 pencils
Small trashcan
Write your name on the paper.
How would it feel to work in the allotted space at the table for the day? Why?

4. Exploration- The Great Table Experiment – How many is too many?
Let’s add 2 more students and their chairs. Write your name on the paper. How would it feel to work in the allotted space at the table for the day? Why?

5. Exploration- The Great Table Experiment – How many is too many?
Let’s add 4 more students and their chairs. Write your name on the paper. How would it feel to work in the allotted space at the table for the day? Why?

6. Exploration- The Great Table Experiment – How many is too many?
Let’s add 5 more students and their chairs. Write your name on the paper. How would it feel to work in the allotted space at the table for the day? Why?

7. Exploration- The Great Table Experiment – How many is too many?
Despite the ample available resources (paper, pencils), you simply cannot all fit. Now, let’s add the remaining students in the class. Clearly, there is not enough space OR resources for everyone. It is simply too crowded!

8. Exploration- The Great Table Experiment – How many is too many?
Now, I invite the original 4 students to crumple their papers and put it in the small trashcan.
Waste disposal is not a problem for the 4 students.
Next, the next 2 people that joined do the same with your paper.
Then, the next 4 people that joined do the same with your paper.
Finally, the last 5 people that joined do the same with your paper.
We see that there is an overabundance of waste and nowhere to dispose of it!

9. Investigating it! Carrying Capacity and Limiting Factors
Science is a social activity; therefore, as scientists, you will work in groups to gain an understanding of carrying capacity and limiting factors.
Your mission is to access the assigned video link and
Define carrying capacity
Name limiting factors
Explain how each limiting factor affects carrying capacity.
Youtube : Serious Science, Biological Carrying Capacity
Youtube : The Adventures of Harry and Jerry, Limiting Factors and Carrying Capacity
Study.com : Carrying Capacity with Animal Populations

10. Explanation – Let’s Discuss!
Discuss the questions, based on the findings gained from the website/videos
In what ways are your findings from the video like the Great Table experiment?
Define the concepts of carrying capacity and limiting factors, using the table experience and data collected from your video.

11. A Balanced Ecosystem Let’s read! Recap:
For organisms to thrive in an ecosystem, there must be sufficient resources, including space, food, and water. Theses resources are known as limiting factors.
To guarantee survival and reproduction of organisms within the aquaponics system, we need to determine the proper number of organisms. This proper number is called carrying capacity.
Too many organisms in an ecosystem drain resources (i.e. not enough food for all and organisms starve; excessive waste pollutes the environment, making it unavailable).

12. Extension – Carrying Capacity in Our Aquaponics System
Discuss with each other how the aquaponics system works and ways they think the concepts of carrying capacity and limiting factors might apply to the aquaponics system. On the bottom of pg 52, describe how would you use your new knowledge of carrying capacity and limiting factors with the aquaponics system?

13. Extension – Carrying Capacity in Our Aquaponics System

14. Extension – Carrying Capacity in Our Aquaponics System
Recap:
A standard aquarium’s fish-to-water ratio is 1 inch of fish per 1 gallon of water. As a partial rationale for this, fish produce waste. In excess, the waste makes the water toxic and harmful to the fish.
Aquaponics systems differ from standard aquariums, as waste released into the water by fish is cycled through a pump into the grow bed. Bacteria in the grow bed filter the water before returning it to the tank, therefore, you can have more than one inch of fish per gallon.
Waste is converted into plant food by bacteria in the grow bed, which supports plant life.
While filtering waste improves fish survival rates, excessive amounts of fish in the system threaten humane treatment of fish, and limit space needed to thrive.
A fine balance exists between the proper number of fish needed to support plant life, and fish over-crowding.

15. Let’s read about Fish Stress and Disease!
…and then finish by revisiting our Carrying Capacity Probe and making adjustments, as needed.