Trophic Levels & Energy Flow

1. Trophic Levels & Energy Flow Chapter 2.3 & 2.4

2. Nutrient Flow Through Ecosystems We have already studied how nutrients flow through ecosystems:

3. Nutrient Flow Through Ecosystems

4. Nutrient Flow Through Ecosystems Notice that nutrients are continuously recycled through ecosystems by decomposers through a process called biodegradation.

5. Energy Flow Through Ecosystems • Define energy: • The ability to make things move, or • The ability to do work. • Law of conservation of energy: • Energy can neither be created nor destroyed, it can only change from one form to another.

6. Energy Flow Through Ecosystems • What is the ultimate source of energy in any ecosystem? • The Sun – it gives off heat and light.

7. Energy Flow Through Ecosystems • What is the only type of organism that can derive energy directly from solar energy? • Producers – they use sunlight to manufacture food by photosynthesis. …

8. Energy Flow Through Ecosystems From there, solar energy indirectly passes to the primary consumers which are also called herbivores.

9. Energy Flow Through Ecosystems From there, solar energy indirectly passes to the secondary consumers which are also called carnivores.

10. Energy Flow Through Ecosystems Finally, this solar energy indirectly passes to the tertiary consumers which are also called top predators or top consumers.

11. Energy Flow Through Ecosystems • So how is the flow of energy different than the flow of nutrients through an ecosystem? • Energy, unlike nutrients, cannot be recycled. • Energy is lost to heat along each step of the pathway. Each organism changes up to 90% of energy gained to heat. (So only 10% of the energy gets passed onto the next organism!)

12. Trophic Levels and Ecological Pyramids Organisms can be arranged by the energy they consume in the shape of a pyramid.

13. Trophic Levels and Ecological Pyramids Each level of this pyramid is called a trophic level and it shows the position of the organism in the energy pyramid. There is less energy as we get nearer the top of the pyramid.

14. Trophic Levels and Ecological Pyramids The pyramid must broad at the base and narrower at the top because energy is lost to heat by each organism as we go up the pyramid, so less energy is available at each trophic level. This limits the number of organisms at each level. There is not enough energy to support large populations at each level.

15. Trophic Levels and Ecological Pyramids The pyramid will never have more that 4 trophic levels because there is not enough energy to support animals at a higher trophic level.

16. Food Chains • Define food chain: • The pathway taken by nutrients through different trophic levels in an ecosystem. (ex. Grazing food chain.)

17. Food Chains • Detritus Food Chain • This is different from a regular food chain because it occurs when left overs (undigestible remains) that cannot be a part of the grazing food chains are left for the detrivores and decomposers to recycle for other consumers.