1. © 2012 John Wiley & Sons, Inc. All rights reserved. Overview of Chapter 3 Energy & Ecosystems – Photosynthesis and Cellular Respiration Flow of Energy Through Ecosystems – Producers, Consumers & Decomposers – Ecological Pyramid – Ecosystem Productivity

2. © 2012 John Wiley & Sons, Inc. All rights reserved. Energy The ability or capacity to do work – Chemical, – Thermal, – Mechanical, – Nuclear, Electrical, and – Radiant/Solar  BASIS OF MOST ECOSYSTEMS Stored energy = potential energy Energy of motion = kinetic energy

3. © 2012 John Wiley & Sons, Inc. All rights reserved. Energy Rules (laws of thermodynamics) – Energy cannot be created or destroyed; it can be changed/converted from one form to another 1 st law of thermodynamics Producers capture energy of sun Consumers must eat other living things (or their waste) – When energy is converted form one form to another, some of it is degraded to heat Second Law of Thermodynamics Energy is lost as it passes from one trophic level to next

4. © 2012 John Wiley & Sons, Inc. All rights reserved. Trophic level Based on main source of nutrition/energy – Producers (fix energy from sun) – Primary consumers (herbivores) – Secondary consumers (predators or detrivores/decomposers) – Tertiary consumers (predators or detrivores/decomposers) – Quartinary consumers (predators or detrivores/decomposers)

5. © 2012 John Wiley & Sons, Inc. All rights reserved.

6. Ecosystem Productivity Gross Primary Productivity (GPP) – Total amount of energy plants capture by photosynthesis Net Primary Productivity (NPP) – Energy captured by photosynthesis minus energy “spent” during cellular respiration GPP (photosyn) – cellular respiration = NPP – Plant growth per unit area per time – Only NPP is available as food to higher trophic levels

7. © 2012 John Wiley & Sons, Inc. All rights reserved. Variation in NPP by Ecosystem

8. © 2012 John Wiley & Sons, Inc. All rights reserved. Ecosystem Productivity Aquatic Ecosystems: Nutrients--#1 Nitrogen & phosphorus Limited by light penetration--#2 Terrestrial ecosystems Temperature and water availability -- #1 Nutrients -- #2 Nitrogen & phosphorus

9. © 2012 John Wiley & Sons, Inc. All rights reserved. Energy Flow Through Ecosystems

10. © 2012 John Wiley & Sons, Inc. All rights reserved. Food Chains

11. © 2012 John Wiley & Sons, Inc. All rights reserved. Food Web

12. © 2012 John Wiley & Sons, Inc. All rights reserved. Food Web

13. © 2012 John Wiley & Sons, Inc. All rights reserved. Pyramid of Energy Amount of energy at each trophic level – (and how much is transferred to the next level)  Most energy is lost between trophic levels  Limits number of levels

14. © 2012 John Wiley & Sons, Inc. All rights reserved. Average 10% efficiency (ranges from 5-20%)

15. © 2012 John Wiley & Sons, Inc. All rights reserved.

16. Number of tropic levels is limited by amount of energy available in ecosystem (i.e., productivity)

17. © 2012 John Wiley & Sons, Inc. All rights reserved. Pyramid of Biomass The amount of living material (biomass) at each level  90% reduction in biomass between trophic levels  Why?

18. © 2012 John Wiley & Sons, Inc. All rights reserved.

19. Pyramid of Numbers Number of individuals at each trophic level  Fewer organisms occupy each successive level  Does not indicate:  biomass of organisms at each level  amount of energy transferred between levels

20. © 2012 John Wiley & Sons, Inc. All rights reserved. Controls on trophic levels Bottom up: – Trophic levels are limited by nutrient availability and biomass of next lower level – Nutrient  producers  1 consumers (herbivores)  2 consumers (predators)… Top Down (trophic cascade) – Consumption by higher levels limits next lower level – Predation  herbivores  producers

21. © 2012 John Wiley & Sons, Inc. All rights reserved. Bioaccumulation The buildup of a persistent toxic substance in an organism’s body, often in fatty tissues – Synthetic chemical do not metabolize well – They remain in the body for extended periods of time DDT Lead Mercury PBDE (flame retardants) Dioxins PCB Phthalates BPA

22. © 2012 John Wiley & Sons, Inc. All rights reserved. Biomagnification The increased concentration of toxic chemicals in the tissues of organisms that are at higher levels in food webs Diagram (right) is example of biomagnification of DDT LD 50 of 113 mg/kg in rats

23. © 2012 John Wiley & Sons, Inc. All rights reserved. Effect of DDT on Bald Eagles

24. © 2012 John Wiley & Sons, Inc. All rights reserved.