WHAT IS AN ECOSYSTEM? An ecosystem is an interrelated system that includes all the autotrophs, heterotrophs, and the physical and chemical factors of the environment at a given place and time. autotrophs Arrows show a transfer of: ENERGY & MATERIALS heterotrophs environment
The 10 % RULE !
The maximum amount of ENERGY that passes from one trophic level to the next is 10%. 90% of the ENERGY at each trophic level is used to keep the organisms alive and is converted to HEAT.
Always start with the SUN.
The 10% RULE ! PHYTOPLANKTON 90% of the ENERGY captured by PRODUCERS is used to keep themselves alive (converted to heat). HEAT Max. 10 % to HERBIVORES
PRODUCERS HERBIVORES 1st Order CARNIVORES Producers are the BASE of the pyramid of biomass because their ENERGY comes direct from the SUN. 2nd Order CARNIVORES 3rd Order CARNIVORES
The 10% RULE ! PHYTOPLANKTON 10% ZOOPLANKTON 90% HEAT 90% was used to keep the HERBIVORES alive. Max. 10 % to CARNIVORES
PRODUCERS HERBIVORES 1st Order CARNIVORES HERBIVORES exist on only 10% of the ENERGY from PRODUCERS. 2nd Order CARNIVORES 3rd Order CARNIVORES
The 10% RULE ! PHYTOPLANKTON 10% ZOOPLANKTON 10% 1st Order CARNIVORES 90% HEAT 10% Max. 10 % to 2nd O. CARNIVORES
PRODUCERS HERBIVORES 1st Order CARNIVORES 2nd Order CARNIVORES 3rd Order CARNIVORES 1st O. Carnivoresare max.10% ofHERBIVORES.
The 10% RULE ! PHYTOPLANKTON 10% ZOOPLANKTON 10% 1st Order CARNIVORES 10% 2nd Order CARNIVORES
PRODUCERS HERBIVORES 1st Order CARNIVORES 2nd Order CARNIVORES 3rd Order CARNIVORES There isn’t much ENERGY left near the top.
PRODUCERS HERBIVORES 1st Order CARNIVORES The 10% RULE . . . 2nd Order CARNIVORES ...results in this ECOLOGICAL PYRAMID 3rd Order CARNIVORES
PRODUCERS - 1000 HERBIVORES - 100 1st Order CARNIVORES - 10 The 10% RULE . . . 2nd Order CARNIVORES - 1 ...is used to help predict NUMBERS. 3rd Order CARNIVORES 0.1
1000 100 10 The 10% RULE . . . 1 ...is used to help predict BIOMASS. 0.1
REVIEW QUESTIONS 1. What is the 10% rule ? 2. Where does most of the ENERGY go at each trophic level ? 3. What 2 things can the ecological pyramid help predict? FOOD WEBS ! Show all the possible FOOD CHAINS. Show all the OMNIVORES. Show multiple feeding preferences.
What causes ecosystems to change? Natural causes: 1 Drought Disease 2 3 Fire 4 Overpopulation
What causes ecosystems to change? Changes caused by humans: 1 Water pollution 2 Air pollution 3 Land pollution 4 Construction
How can humans help to prevent changes in ecosystems? 1 Use resources wisely 2 Laws that control pollution 3 Clean up litter 4 Keep rivers and lakes clean
Now let’s take a closer look at the food web you created. What would happen if you removed one of the organisms from the food web? Are there other organisms that could take its place? How would the organism’s predators/grazers respond? How would the organism’s prey/food respond? Let’s start at the top and try a few scenarios: • 1) What would you hypothesize might happen to the other organisms in the web, if killer whales went extinct? • 2) What might happen if we exhausted the fishery (through over fishing), and fish were no longer a component of our food web? • 3) What might happen if we removed the algae from the food web? • 4) Which scenario above affected the most organisms? • 5) What does this tell you about the importance of the base of the food web?