Understanding Energy Transfer in Ecosystems: Key Concepts, Terms & Examples

1. Energy Transfer in Ecosystems

2. Terms to be Familiar with • Ecosystem • Biotic • Abiotic • Producer • Consumer • Herbivore • Carnivore • Omnivore • Scavenger • Decomposer/Detritovore • Parasite

3. A step-by-step sequence linking organisms that feed on each other. A food chain always begins with producers (plants). Arrows are used to show direction of energy transfer.

4. Trophic Levels • Feeding level • Producers = 1st trophic level (most energy available) • Primary consumers feed on producers (2nd trophic level) • Secondary consumers feed on primary consumers (3rd trophic level) • Tertiary consumers (4th trophic level) Quartenary consumer Primary Secondary Tertiary Consumer

5. Energy Transfer • The sun provides energy for producers to grow. Producers use the sun’s energy to: • Perform photosynthesis – Transforms Solar E -- Chemical E (glucose) - Plants use the stored chemical energy to “fuel” their metabolism. • (Run chemical reactions which result in Growth, Make nectar, Active transport) • This Chemical E is transferred from producer to consumer when a consumer eats a plant.

6. Energy Transfer • Animals do not store all of the energy they obtain from a plant. They use it to: • Move • Pump blood • Digest food • Other Chemical reactions • Most E from food is “burned” to maintain our body temperature • Once the energy has been used, it is not available to be transferred. • Only ~10% of the energy at each trophic level gets transferred to the next one.

7. 100% of original energy 2% of original energy 0.2% of original energy 0.02% of original energy 0.002% of original energy Phyto- plankton Zoo- plankton Smelt (fish) Sun salmon humans Energy Transfer • A food chain is usually limited to 5 trophic levels.

8. Food Webs • A diagram that shows the feeding relationship between organisms in an ecosystem. • The arrows indicate the direction of energy transfer. Source of E -> Recipient • A food web consists of many food chains. • More chains and interconnections supports a more stable ecosystem

9. Keystone Species • A species that plays a vital role in stabilizing the ecosystem. Removal of a keystone species will cause a chain reaction involving many other species in the ecosystem. Wolves of Yellowstone

10. Wolves of Yellowstone • Trophic Cascade powerful interactions that can control entire ecosystems. • Occur when predators limit the density (#/area) and/or behavior of their prey and thereby enhance survival of the next lower trophic level. • Effects of the presence/absence of the keystone species “cascades” down the food chain

11. Check your Understanding • Food Chain Gizmo | ExploreLearning

12. Try This • In a forest community, green plants of many types form the start of the food web as the producers. One small food web that can be identified is one starting with these green plants that are eaten by the cankerworm. The cankerworm is eaten by the red-eyed vireo (a bird). Rabbits also feed from the green plants, and they are eaten by the bobcats. Both the rabbit and the bobcat are eaten by lice which live in their fur. These lice are eaten by the red-eyed vireos in the forest. It has been noted that both the red-eyed vireos and the rabbits are eaten by sharp-shinned hawks in the area.