1. Energy Flow Through an Ecosystem
Activity 7
Energy Flow Through an Ecosystem

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3. Read the introduction
What examples of producers and consumers did you see in the previous activity?

4. Get Started
Ask the students what the diagram shows about the relationships of organisms in the diagram. Students should conclude that because the images of the organisms are simply in a line, the diagram does not tell anything of the interrelationships or of the energy that flows from one to the next.
Note: This image is taken from Transparency 7.1, “Organisms in an Ecosystem.”

5. Get Started
Ask the students about the relationships between organism in the figure, and the flow of energy between the organisms. Students should understand that the arrows indicate the flow of energy between organisms.
Note: This image is taken from Transparency 7.2, “Food Web for an Ecosystem.”

6. Challenge
How can we use food webs to predict the short- and long-term effects of particular events on an ecosystem?

7. Part A
In step 8, when adding arrows to your food web, the arrows should point in the direction of the organism that is doing the eating to represent the pathway of energy.

8. Part B
For step 13, be sure to discuss the short- and long-term effects of the event on the ecosystem.
See your Teacher’s Edition for sample student responses.

9. Which level in the energy pyramid contains the most energy?
Which level contains the least amount of energy?
The lowest/bottom level contains the most energy and the top/highest level contains the least amount of energy.

10. Why is there a different amount of energy available to the producers than to the tertiary consumers? What happened to the energy?
Some of the energy is stored in the organism and some is lost to the environment as heat.

11. Analysis 2
What is the difference between the role of an organism that is a producer and one that is a consumer? How is a decomposer different from other consumers?
Analysis Question 2 may be scored using the Understanding Concepts (UC) scoring variable. More information and a sample student response can be found in your Teacher’s Edition for this activity, and in Teacher Resources IV: Assessment.

12. Analysis 3 Explain the role of the sun in the kelp forest ecosystem.
Analysis Question 3 may be scored using the Understanding Concepts (UC) scoring variable. More information and a sample student response can be found in your Teacher’s Edition for this activity, and in Teacher Resources IV: Assessment.

13. Analysis 4 Describe the flow of energy in the kelp forest ecosystem.
Analysis Question 4 may be scored using the Understanding Concepts (UC) scoring variable. More information and a sample student response can be found in your Teacher’s Edition for this activity, and in Teacher Resources IV: Assessment.

14. Analysis 7
Imagine you are an ecologist who studies kelp forest ecosystems. You have been asked by the federal government to evaluate two plans for managing the California sheephead fishery, which relies on kelp forests. A summary of two proposals follows. Read the proposals and determine:
A. how the two proposals differ.
B. which proposal do you think the government should implement
In your recommendation include a discussion of the trade-offs you considered.
Question continues on the next two slides.

15. Cost to implement this proposal: $750,000
Proposal A
Take population counts of California sheepheads once every three months.
If the fish population is below sustainable levels, decrease the size of the allowed sheephead catch. If the sheephead population is at or above sustainable levels, keep the catch limit at current levels.
Cost to implement this proposal: $750,000
Question continues on the next slide.

16. Cost to implement this proposal: $1,250,000
Proposal B
Take population counts of California sheepheads and sea urchins once every three months.
If the size of any population is below sustainable levels, decrease the size of the sheephead catch allowed. If the size of each population is at or above sustainable levels, keep the sheephead catch limit at current levels.
Cost to implement this proposal: $1,250,000
Analysis Question 7b is a Quick Check assessment opportunity to assess students’ identification and comparison of trade-offs in the two proposals. See your Teacher’s Edition for a sample student response.

17. Revisit the Challenge
How can we use food webs to predict the short- and long-term effects of particular events on an ecosystem?
Return to the KWL chart from Activities 1 and 3 and add to the “What I Learned” column.
Sample answers to the complete KWL can be found in your Teacher’s Edition.

18. biodiversity consumers decomposers energy pyramid food web producers
Key Vocabulary
biodiversity
consumers
decomposers
energy pyramid
food web
producers
See Teacher Resources III: Literacy for more information on key vocabulary and the most effective strategies to enhance student vocabulary learning.
Note that bold words are formally defined in this activity. Words in regular font are used in the activity, but not formally defined. The definition of a key vocabulary word should not be discussed as a class prior to the formal definition being introduced.