Energy in Ecosystems

Ecosystem Components Producers Basis of an ecosystem’s energy Autotrophs: perform photosynthesis to make sugars Chemotrophs: Bacteria which use minerals from deep-sea vents to make energy Consumers Heterotrophs: Consumes others for energy Omnivores, herbivores, carnivores, decomposers, detritivores

4.5897 kcal 45.897 kcal 458.97 kcal 4589.7 kcal 45,897 kcal Trophic Levels 4.5897 kcal 45.897 kcal Defined: Feeding level of an ecosystem Trophic levels consist of producers, consumers, and decomposers ~ 10% of energy is passed to the next level ~ 90% is used by the organism or lost as heat If there are 45, 897 kcal at the primary producer trophic level, how much energy is available to the other trophic levels? Food chains contain few trophic levels 458.97 kcal 4589.7 kcal 45,897 kcal

Food Chains 1st trophic level = Producers Autotrophs (perform photosynthesis) Bottom (basis) of food chain Ex: Plants, algae, cyanobacteria

Food Chains 2nd trophic level = Primary consumers Feed on producers Herbivores (plant eaters)

Food Chains 3rd trophic level = Secondary consumers Feed on primary consumers Omnivores and carnivores

Food Chains 4th trophic level = Tertiary consumers Feed on secondary consumers Omnivores and carnivores

Food Chains 5th trophic level = Quaternary consumers Feed on Tertiary consumers Omnivores and carnivores

Decomposers Rarely shown on food chains Feed on any food chain level when organisms die Detritivores: Feed/ingest dead matter Decomposers: secrete enzymes to break down dead matter and then absorb the nutrients

What’s wrong with this food chain? Food Chain Analysis What’s wrong with this food chain? The arrows are pointing the wrong direction. This implies that the plant eats the grasshopper.

What’s wrong with this food chain? The arrows are pointing the wrong direction. This implies that the grasshopper eats the mouse.

What’s wrong with this food chain? The arrows are pointing the wrong direction. This implies that the mouse eats the snake.

What’s wrong with this food chain? The arrows are pointing the wrong direction. This implies that the snake eats the hawk.

On your paper fix the arrows so they show the correct direction energy travels… Now the arrows show the direction that energy is passed up the food chain.

tertiary consumer secondary consumer primary consumer producer Energy Pyramids Defined: diagram that compares energy used by producers & other organisms on trophic levels. Label the tropic levels in this energy pyramid tertiary consumer secondary consumer primary consumer producer

Food Webs Defined: Group of interrelated food chains Arrows show direction energy (nutrients) travel Analysis Trace 2 food chains from this food web. Food Webs Defined: Group of interrelated food chains Arrows show direction energy (nutrients) travel

Analysis: Highlight a food chain from this food web. Then label each trophic level. Tertiary consumer Secondary consumer Primary consumer producer

Analysis: Highlight a food chain from this food web. Then label each trophic level. Quaternary consumer Tertiary consumer Secondary consumer Primary consumer producer

Analysis What could happen if the grasshoppers die out due to pesticide use?

X Owl death (less blue jays to eat) Blue jay death (less spiders to eat) Spider death (no more grasshoppers to eat) Squirrel increase (less owls hunting them) X

YouTube Food Chain Video

Review How many trophic levels are in the following food chain? Apple tree  Worms  Blue Jay  Owl If the tree in the example above makes 15,000 calories of energy from photosynthesis, how much energy is available for each other trophic level? In the food chain above, which is the producer? In the food chain above, which is the primary consumer? In the food chain above, which is the tertiary consumer? Which level consumer are herbivores known as? What is the lowest consumer level possible for a carnivore? Examine the food web on the previous slides. Find a complete food chain that is 6 trophic levels from start to finish. Why do food chains contain few trophic levels?

Review Answers How many trophic levels are in the following food chain? Four Apple tree  Worms  Blue Jay  Owl Primary Producer, Primary Consumer, Secondary Consumer, Tertiary Consumer If the tree in the example above makes 15,000 calories of energy from photosynthesis, how much energy is available for each other trophic level? 1500 kcal 150 kcal 15 kcal In the food chain above, which is the producer? Apple Tree In the food chain above, which is the primary consumer? Worms In the food chain above, which is the tertiary consumer? Owl Which level consumer are herbivores known as? Primary Consumer What is the lowest consumer level possible for a carnivore? Secondary Consumer

Examine the food web on the previous slides Examine the food web on the previous slides. Find a complete food chain that is 6 trophic levels from start to finish. Grass, Grasshopper, Spider, Blue Jay, Cat or Owl, Hawk Why do food chains contain few trophic levels? Because only ~ 10% of energy is passed from one trophic level to the next, the longer the food chain, the more energy is lost overall. Less energy means there are less resources for the organisms in a particular trophic level.