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The Structure of Ecosystems- Trophic Pyramids and Food Webs

The Structure of Ecosystems- Trophic Pyramids and Food Webs. Autotrophs and Producers. Get energy from sunlight ( photoautotrophs ) Ex. Plants, algae, phytoplankton (in aquatic ecosystems) OR get energy from chemicals ( chemoautotrophs )

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The Structure of Ecosystems- Trophic Pyramids and Food Webs

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  1. The Structure of Ecosystems- Trophic Pyramids and Food Webs

  2. Autotrophs and Producers • Get energy from sunlight (photoautotrophs) • Ex. Plants, algae, phytoplankton (in aquatic ecosystems) • OR get energy from chemicals (chemoautotrophs) • Ex. Chemosynthetic bacteria living at deep sea vents or in hot springs/geysers that use toxic chemicals to make food

  3. Consumers and Heterotrophs • Get energy from consuming other organisms • Can be herbivores (primary consumers) • Ex. Cows, bunnies, mushrooms • OR can be carnivores (secondary consumers) • Ex. Snakes, wolves, lions

  4. Food Chain • Series of steps in an ecosystem in which energy is transferred among individuals by eating and being eaten • Ex. ________  ______  ________

  5. Food Web • The variety of feeding interactions among organisms within an ecosystem • Can be very complex because several species of consumers may feed on the same species, and one species may feed on several species • What is an example of this in your surrounding environment?

  6. Food Web example

  7. Energy in Food Webs and Food Chains • All organisms require energy • The total energy at the base of the food web (producers) determines the energy available for the entire ecosystem • How does energy passes through an ecosystem? • Relationship between producers and consumers form the ecosystem’s trophic structure • This pattern of relationships determines the flow of energy and nutrients in an ecosystem

  8. Trophic Structure • 1st Level= Producers: (such as plants) make up the trophic level that supports the ecosystem • Photosynthesis: process by which an organism makes its own food using light • Chemosynthesis: process by which an organism makes its own food using chemicals • The other levels include consumers that depend either directly or indirectly on the producers for nutrients and energy • The main producers in ecosystems on land are plants • The main producers in aquatic ecosystems are algae

  9. Food Web example . .

  10. Trophic Structure • 2nd Level= Herbivores: (organisms that consume plants or algae) are primary consumers • Ex: Deer, grasshoppers, and garden snails • 3rd Level= Carnivores: (meat eaters) are secondary consumers that eat herbivores • Ex: wolves and most fish • 4th Level= carnivores that eat the carnivores called tertiary consumers • Ex: Hawks

  11. . . . . Food Web example . . . . . . . . . . . . . . . . . .

  12. Trophic Structure • Decomposers: consume organic wastes and dead organisms from all trophic levels • Ex: bacteria, fungi (primary decomposers), other examples= earthworms, cockroaches, scavengers, etc.

  13. Interactive Demonstration with white boards • http://www.eduweb.com/portfolio/earthsystems/food/foodweb4.html

  14. Trophic/Energy Pyramid

  15. Trophic/Energy Pyramid • The area of each level represents the quantity of energy it receives from the level below • In many ecosystems each level receives about 1/10 of the energy from the level below it= 10% Rule • The other 90% is used for • Metabolism • Movement • Released as heat energy

  16. Trophic/Energy Pyramid • Biomass ( the total amount of living matter at each trophic level) decreases at higher trophic level as does energy • Ex: the total mass of all wolves in the forest is much less than the mass of rabbits and other prey or the mass of trees and other plants. • Why can’t there be more wolves than there are rabbits? • Productivity: the rate at which new biomass forms • Predict the trophic level where the most productivity has to take place? • Highest among primary producers, and declines at higher trophic levels

  17. Productivity • Remember the definition of Productivity: the rate at which new biomass forms • Gross primary productivity= the TOTAL amount of new organic matter that is developed through photosynthesis and chemosynthesis • Net primary productivity= the remaining amount of organic matter after some is used to sustain life

  18. Invasive Species • What are invasive species? • Non-native species that can disrupt and/or replace native species. • Ex: Zebra Mussles of the Great Lakes • What are some problems that invasive species could cause? • WebQuest Tomorrow to answer this question and more in more detail=)

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