Energy Transfer in an Ecosystem

1. Energy Transfer in an Ecosystem

2. Why do organisms need energy? • To carry out essential functions • Growth • Movement • Maintenance • Repair • Reproduction The amount of energy an ecosystem receives and the amount that is transferred from organism to organism affect the ecosystem’s structure!!!!!

3. Producers • Organisms that manufacture their own foods by capturing energy and using it to make organic molecules • Plants (Terrestrial) • Some protists (Aquatic) • Some bacteria (Aquatic)

4. Producers • Photosynthetic • Use solar energy to power the production of food • Chemosynthetic • Use energy stored in inorganic molecules to produce carbohydrates

5. Measuring Productivity by Producers • Gross primary productivity • Rate at which producers capture the energy of sunlight by producing organic compounds • Biomass • Organic material produced • Only energy stored as biomass is available to other organisms in ecosystems

6. Net Primary Productivity • The rate at which biomass accumulates • NPP = GPP-Rate of respiration in producers • Expressed in either: • Units of energy per unit area per year (kcal/m2/y) • Units of dry organic mass per unit area per year (g/m2/y)

7. Comparative Productivity of Ecosystems • NPP can vary greatly between ecosystems • Variation in terrestrial ecosystems due to light, temperature, and precipitation • Variation in aquatic ecosystems due to light and availability of nutrients Cairns, Australia

8. Comparative Productivity of Ecosystems • What does this graph tell us about rain forests? • Average NPP of a tropical rainforest is 25 times greater than the rate in a desert the same size Although rainforests account for only 5% of the Earth’s surface, they produce 30% of the Earths NPP

9. Consumers • Heterotrophs that cannot manufacture their own food • Get energy by eating other organisms or organic wastes • All animals, most protists, all fungi, many bacteria

10. Types of Consumers • What are 4 types of consumers? • Herbivores • Carnivores • Omnivores • Detritivores

11. Herbivores vs. Detritivores Herbivores Detrirtivores Feed on the “garbage” of an ecosystem Ex] Earthworm Waste, such as dead organisms, fallen leaves, and wastes = detritus Decomposers are those bacteria and fungi that cause decay by breaking down complex molecules • Eat producers • Ex] Giant panda

12. Carnivore vs. Omnivore Carnivore Omnivore Eat both consumers and producers Ex] Pigs • Eat other consumers • Ex] Lions

13. Create your own graphic • Label the types of organisms according to energy flow Producers: make energy-storing molecules Carnivores: consume herbivores Herbivores: consume producers Omnivores: consume producers & herbivores Detritivores: consume producers, herbivores, carnivores, and omnivores

14. Energy Flow • When an organism eats another, energy is transferred • Therefore energy flows from producers to consumers • Group organisms based on energy flow in an ecosystem

15. Food Chains and Food Webs Food Chain Food Web Interrelated pathway of food chains in an ecosystem • A single pathway of feeding relationships in an ecosystem

16. Energy Transfer • On average, only 10% of the total energy consumed in one level is incorporated into the next level. • Why so low? • Some escape being eaten • Some die and decompose • Some used for cellular respiration • Some can’t be broken down • Some lost as heat from metabolism

17. Limitations of Trophic Levels • Low rate of energy transfer explains why there are only a few trophic levels in an ecosystem • High trophic levels contain less energy, so they can only support a few individuals

18. What is the organic material in an ecosystem called? Biomass

19. What is an organism called that eats both producers and consumers? Omnivore

20. How much of the total energy is transferred from one trophic level to the next? Approximately 10%