2. Energy Flow Through Ecosystems
- energy pyramids
-biomass pyramids
-bioaccumulation/biomagnification

3. Energy Pyramid/Ecological Pyramid
Shows how energy flows through an ecosystem
The sun: provides initial energy through photosynthesis
The first trophic level is composed of autotrophs

4. Sample Energy Pyramid

5. Energy Pyramid
At each trophic level 90% of the energy is LOST as HEAT or due to life processes
Only 10% of energy is transferred from one trophic level to another

6. Based on this pyramid, what is happening to the energy?
Heat
Heat
Heat
Heat

7. Biomass Pyramid
Shows the WEIGHT of living material at each trophic level
Each bar of the biomass pyramid represents the amount of biomass within a trophic level
Biomass decreases with each trophic level

8. Pyramid of Biomass

9. What do you think happens when pesticide is sprayed. Where does it go
What do you think happens when pesticide is sprayed? Where does it go? Does it only target the animal it is intended for?

10. Bioaccumulation
The building up (accumulation) of a toxic substance in an organism
The toxin builds up, and remains in the fatty tissue of an organism

11. Biomagnification
The concentration of the toxic substance increases as you go up a food chain
It becomes more deadly as you go up the food chain

12. Where is the most Mercury?
Top Predator
Hg = Mercury
Where is the most Mercury?

13. Real Life Examples
DDT is a pesticide used to kill mosquitos and agricultural pests
DDT was sprayed in the 1940’s and 1950’s

14. DDT traveled from the bottom of the food chain and increased in concentration
Shrew
Grasshopper
Hawk

15. Result of DDT
Due to the biomagnification of DDT, large predatory birds like Bald Eagles, have high concentrations of DDT
The DDT caused these birds to lay eggs with thin shells
Predatory Bird populations dropped significantly, and some almost went extinct

16. Other Real Life Examples
Water has been polluted with Mercury and PCB’s (polychlorinated biphenyl)
Both chemicals are carcinogenic (cancer causing)
They can cause neurological issues, infertility, and deformities
PCB’s are what is found in the Hudson River

17. the concentration of a toxin
Where is the greatest
amount of
pesticide?
Even though there are
less organisms
at the top of a food
chain/web
the concentration of a toxin
is greater at the top
than at the bottom
Key:
Dots equal
Pesticide

18. Bald Eagle Video