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?