1. Food Chains, Food Webs, and the Transfer of Energy
Unit 2: Ecosystems
Food Chains, Food Webs, and the Transfer of Energy

2. The study of the interactions between organisms and their environment.
ECOLOGY
The study of the interactions between organisms and their environment.

3. The Nature of Ecology
Ecosystem organization
Organisms
Populations
Communities
Ecosystems
Biosphere

4. The Earth’s Life-Support Systems
Troposphere
Stratosphere
Hydrosphere
Lithosphere
Biosphere

5. Sustaining Life of Earth
One-way
Flow of energy
Cycling of matter

6. Ecosystem Services and Sustainability

7. ENVIRONMENT = all the factors that affect an organism.
ABIOTIC FACTOR =
non-living factors in an environment.
BIOTIC FACTORS =
living factors in an environment.

9. HABITAT = place where an organism or population of organisms live.
NICHE = the role or job of a species in an ecosystem.

10. Biosphere
Ecosystems
Communities
Populations
Organisms

11. ECOSYSTEM includes all the biotic & abiotic factors in an environment.

13. Autotrophs
A groups of organisms that can use the energy in sunlight to convert water and carbon dioxide into Glucose (food)
Autotrophs are also called Producers because they produce all of the food that heterotrophs use
Without autotrophs, there would be no life on this planet
Ex. Plants and Algae

14. Autotrophs

15. Autotrophs Chemotrophs
Autotrophs that get their energy from inorganic substances, such as salt
Live deep down in the ocean where there is no sunlight
Ex. Bacteria and Deep Sea Worms

16. Heterotrophs Organisms that do not make their own food
Another term for Heterotroph is consumer because they consume other organisms in order to live
Ex. Rabbits, Deer, Mushrooms

17. Heterotrophs

18. Heterotrophs Consumers
1. Scavengers/Detritivores – feed on the tissue of dead organisms (both plans and animals)
Ex. – Vultures, Crows, and Shrimp

19. Heterotrophs Consumers 2. Herbivores – eat ONLY plants
Ex. – Cows, Elephants, Giraffes

20. Heterotrophs Consumers 3. Carnivores – eat ONLY meat
Ex. – Lions, Tigers, Sharks

21. Heterotrophs Consumers 4. Omnivores – eat BOTH plants and animals
Ex. – Bears and Humans

22. Heterotrophs Consumers
5. Decomposers – absorb any dead material and break it down into simple nutrients or fertilizers
Ex. – Bacteria and Mushrooms

23. Transfer of Energy
When a zebra eats the grass, it does not obtain all of the energy the grass has (much of it is not eaten)
When a lion eats a zebra, it does not get all of the energy from the zebra (much of it is lost as heat)

24. Transfer of Energy
The two (2) previous examples of energy transfer show that no organism EVER receives all of the energy from the organism they just ate
Only 10% of the energy from one trophic level is transferred to the next – this is called the 10% law

25. Trophic Levels
Energy moves from one organisms to another when it is eaten
Each step in this transfer of energy is know as a trophic level
The main trophic levels are producers, consumers, and decomposers

26. Food Chains
The energy flow from one trophic level to the other is know as a food chain
A food chain is simple and direct
It involves one organism at each trophic level
Primary Consumers – eat autotrophs (producers)
Secondary Consumers – eat the primary consumers
Tertiary Consumers – eat the secondary consumers
Decomposers – bacteria and fungi that break down dead organisms and recycle the material back into the environment

27. FOOD CHAIN = used to show how matter & energy move through an ecosystem.

28. Food Chain

29. Ocean Ecosystem Structure
Trophic levels
and dynamics

30. ENERGY

32. How about Mass Transfer?

33. Food Web Most organisms eat more the JUST one organism
When more organism are involved it is know as a FOOD WEB
Food webs are more complex and involve lots of organisms

34. FOOD WEB = shows all the possible food chains in an ecosystem

35. Food Web
Notice that the direction the arrow points  the arrow points in the direction of the energy transfer, NOT “what ate what”

36. Food Web

39. Working at Little Rock Lake in Wisconsin, researchers tracked the connections in the food web-predators like the smallmouth bass at the top and tiny free-floating plants (phytoplankton) at the bottom. (BBC NEWS)

40. Ecological Pyramid
An ecological pyramid shows the relationship between consumers and producers at different trophic levels in an ecosystem
Shows the relative amounts of energy or matter contained at each trophic level
The Pyramid shows which level has the most energy and the highest number of organisms

41. ECOLOGICAL PYRAMIDS
Are graphical models of the quantitative differences that exist between the trophic levels of a single ecosystem.
In accordance to the 2nd Law of Thermodynamics, there is a tendency for numbers and quantities to biomass and energy to decrease along food chains, therefore the pyramids become narrower toward the top.

42. Ecological Pyramid

43. Ecological Pyramid

44. Ecological Pyramid Which level has the most energy?
Which level has the most organisms?
Which level has the least organisms?
Which level has the least energy?

45. A few large producers (the trees) support a much larger number of
Grassland
(summer)
Temperate Forest
Producers
Primary consumers
Secondary consumers
Tertiary consumers
A few large producers (the trees) support a much larger number of
Small primary consumers (insects) that feed on the trees.

46. Biomass
The total mass of the organic matter at each trophic level is called biomass
Biomass is just another term for potential energy – energy that is to be eaten and used.
The transfer of energy from one level to another is very inefficient (10% Law)

47. Biomass

48. PYRAMID OF BIOMASS represent the standing stock at each trophic level.
Units:
J m-2 or
g m-2

49. Abandoned Field
Ocean
Tertiary consumers
Secondary consumers
Primary consumers
Producers
In open waters of aquatic ecosystems, the biomass primary consumers (zooplankton) can exceed that of producers. The zooplankton eat the Producers (phytoplankton) as fast as they reproduce, so their population is never very large.

50. PYRAMID OF PRODUCTIVITY represents the flow of energy through each trophic level.
Units:
J m-2 yr-1 or
g m-2 yr-1

51. As you move up each trophic level, only 10% of the energy is transferred.
The other 90% is used for everyday life functions, metabolism.

53. Pyramid structure affects
the functioning of an
ecosystem.
Bioaccumulation

54. Symbiosis
A close and permanent association between organisms of different species
Commensalism – a relationship in which one organism benefits and the other is not affected
Example: Barnacles on a whale
Mutualism – a relationship in which both organisms benefit from each other
Example: Birds eating pest off a rhino’s back
Parasitism – A relationship in which one organism benefits and the other is harmed
Example: Ticks on a dog

55. Ecological Succession
A change in the community in which new populations of organisms gradually replace existing ones
1. Primary Succession – occurs in an area where there is no existing communities and for some reason (s) a new community of organisms move into the area

56. Ecological Succession
A change in the community in which new populations of organisms gradually replace existing ones
2. Secondary Succession – occurs in an area where an existing community is partially damaged

57. Ecological Succession
A change in the community in which new populations of organisms gradually replace existing ones
3. Climax Community – a community that is stable and has a great diversity of organisms