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

2. Organisms in an Ecosystem
As you view the diagram on the next slide…
Identify which organisms are PRODUCERS and which are CONSUMERS
What are some different types of consumers?
What relationships do you observe?
How does energy flow through these organisms

3. 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. FOOD CHAIN: shows the flow of energy through a series of organisms

7. 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.”

8. Read the Introduction What is kelp?
To what land biome do kelp forests compare?
What is a food web?
What are decomposers?

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

10. Roles of organisms in Ecosystems
Separate the organism cards into 2 or more groups.
Record your responses in your notebook

11. FOOD WEB

12. Food Web - Interconnected Food Chain. .
The arrow in a food web always points toward the consumer in the direction of the flow of energy
TROPHIC LEVELS:
Tertiary Consumer – Hawk
Secondary Consumer – Bird
Primary Consumer – grasshopper
Producer - Grass

13. TROPHIC LEVELS

14. Create a Food Web Start with the kelp card
Place other producers on either side
Build from the producers to the primary consumers…then to the secondary consumers…and so on
Once you have built your food web…draw it on chart paper
Be sure ARROWS point in the right direction to show flow of energy
See your Teacher’s Edition for sample student responses.

15. FOOD CHAIN

16. Which level in the energy pyramid contains the most energy?
What happens to energy as it flows through the ecosystem?
Why is there a different amount of energy available to the producers than to the tertiary consumers? What happened to the energy?
The lowest/bottom level contains the most energy and the top/highest level contains the least amount of energy.

17. Now use different colors to color code each trophic level in your food web
Can an organism occupy more than one trophic level?
Give an example from your food web

18. IMPACT OF EVENTS/ACTIONS ON ECOSYSTEMS
Go through the event cards…one at a time
Summarize the event in the table
Predict short term and long term effects

19. ENERGY PYRAMIDS

20. Ecological Pyramid – shows the amount of energy or matter contained within each trophic level.
Pyramids (Diagrams) that show the transfer of:
Energy
Biomass – amount of living matter at each trophic level
Population Size – relative # of organisms at each trophic level

21. Trophic Level = Energy Level.
SUN
Scavengers, decomposers
Only 10 percent of energy goes to the next level. The rest is either used or lost as heat.
4th trophic level
3rd heterotroph
(3rd consumer)
Carnivore- eats meat
Trophic Level = Energy Level.
As move up the pyramid energy is lost so the
amount of energy decreases.
Energy must be replaced by the sun.
3rd trophic level
2nd heterotroph (2nd consumer)
Carnivore- eats herbivore
2nd trophic level
1st heterotroph (1st consumer)
Herbivore- eats plants
1st trophic level.
Autotroph- plant.
Producer.

22. ENERGY PYRAMID
Complete an Energy Pyramid for your marine kelp food web

23. ANALYSIS
Answer questions 1-7

24. 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.

25. 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.

26. 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.

27. 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.

28. 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.

29. 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.

30. 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.

31. 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.