ECOSYSTEM
An ecosystem is an interrelatedsystem that includes all the
autotrophs, heterotrophs, and the physical and chemical factors
of the environmentat a given place and time.
WHAT IS AN ECOSYSTEM?
autotrophs
heterotrophs environment
Arrows showa transfer of:ENERGY &MATERIALS
The10 %
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 startwith the SUN.
PHYTOPLANKTON
The 10% RULE !
90% of theENERGY captured
by PRODUCERSis used to keep
themselvesalive (converted
to heat).
Max. 10 % toHERBIVORES
HEAT
PRODUCERSHERBIVORES
1st OrderCARNIVORES
2nd OrderCARNIVORES
3rd OrderCARNIVORES
Producers are the BASEof the pyramid of biomass because
their ENERGY comes directfrom the SUN.
ZOOPLA
NKTONPHYTOPLA
NKTONThe 10% RULE !
10%
HEAT
Max. 10 % toCARNIVORES
90%
90% was usedto keep the
HERBIVORESalive.
PRODUCERSHERBIVORES
1st OrderCARNIVORES
2nd OrderCARNIVORES
3rd OrderCARNIVORES
HERBIVORESexist on only 10%
of the ENERGYfrom PRODUCERS.
ZOOPLA
NKTONPHYTOPLA
NKTON
1st Order C
ARNIVORES
The 10% RULE !
90%
HEAT
Max. 10 % to2nd O. CARNIVORES
10%
10%
10%
PRODUCERSHERBIVORES
1st OrderCARNIVORES
2nd OrderCARNIVORES
3rd OrderCARNIVORES
1st O. Carnivores are max.10%of HERBIVORES.
ZOOPLA
NKTONPHYTOPLA
NKTON
1st Order C
ARNIVORES
2nd Order CARNIVORES
The 10% RULE !
10%
10%
10%
PRODUCERSHERBIVORES
1st OrderCARNIVORES
2nd OrderCARNIVORES
3rd OrderCARNIVORESThere isn’t much
ENERGY left near the top.
PRODUCERSHERBIVORES
1st OrderCARNIVORES
2nd OrderCARNIVORES
3rd OrderCARNIVORES
The 10% RULE . . .
...resultsin this
ECOLOGICALPYRAMID
PRODUCERS - 1000HERBIVORES - 100
1st OrderCARNIVORES - 10
2nd OrderCARNIVORES - 1
3rd OrderCARNIVORES
0.1
The 10% RULE . . .
...is usedto helppredict
NUMBERS.
1000100
101
0.1
The 10% RULE . . .
...is usedto helppredict
BIOMASS.
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?
REVIEW QUESTIONS
FOOD WEBS !Show all the possible FOOD CHAINS.
Show all the OMNIVORES.
Show multiple feeding preferences.
What causes ecosystems to change?
Natural causes:
Drought
Disease
Fire
Overpopulation
3
2
1
4
What causes ecosystems to change?
Changes caused by humans:
Water pollution
Air pollution
Land pollution
Construction
1
2
3
4
How can humans help to prevent changes in ecosystems?
Use resources wisely
Laws that control pollution
Clean up litter
Keep rivers and lakes clean
1
2
3
4
Organism Trophic Type Prey/Food Predators/Grazers
algae primary producer --- krill, fish, blue whales
birds carnivorous consumer krill, fish seals, killer whales
blue whales
planktivorous consumer algae, krill killer whales
fish omnivorous consumer algae, krill birds, seals, killer
whales
killer whales top consumer blue whales, fish,
birds, seals ---
krill herbivorous consumer algae fish, blue whales,
birds
seals carnivorous consumer fish, birds killer whales
DESIGN A FOOD WEB USING THE BELOW INFORMATION
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?