1. The Ecosystem
An Introduction

2. Ecosystem
A community of interdependent organisms and the interactions with the physical environment in which they live.
It can also be defined as the abiotic and biotic factors and the interactions between them.
The interaction between organisms and the environment is the key!

3. Differentiate between the following terms:
Organism
Species
Population
Community
Niche
Habitat

4. In your notebook, draw a picture of a bunch of little organisms
Label: The organisms of the same type (species)
Circle: individuals of the same species (Population)
Draw interactions between the populations (Community)

5. Compare the terms habitat and niche
Sometimes people confuse these terms.
Figure out the differences between the terms.

6. Niche vs habitat
A habitat is wear an organism lives. The habitat must provide a source of food, water and shelter for the organism.
Niche: The role of the organism. This is largely to do with the trophic level of the organism.
For example: plants produce food for the rest of the food chain. Tigers keep herbivore populations under control.

7. Abiotic and Biotic factors
Biotic Factor: A living, biological factor that may influence an organism or a system.
Example: predation, disease, competition
Abiotic factor: A non-living, physical factor that may influence an organism or a system
Examples: Temperature, salinity, pH, light

8. Which factors are biotic?
Rabbits
Cacti
Daylight hours
Precipitation
Moss
Soil composition
Bacteria

9. Limiting factors
An abiotic factor can limit the population size if there is too much or too little of it. Even if there is the right amount of other factors
Examples to consider:
Sunlight
Precipitation
Salinity
Nutrients in the soil

10. Trophic levels
Ecostems are often broken up and described according to feeding relationships.
Trophic level:
The position of an organism in a food chain
A group of organisms that occupy the same place in a food chain

11. Trophic levels in food chains
Be able to give an example of each!
Primary producers (autotrophs)
Primary consumers (herbivores)
Secondary consumers(carnivores)
Tertiary consumers (top carnivores)
Decomposers
Detrivores
Scavengers

12. Energy flow and material cycling

13. Producer lAutotroph - “self” + “feed”
lAn organism that obtains organic food molecules without eating other organisms but by using energy from the sun or inorganic molecules to make organic molecules
lRemember: This trophic level supports all of the others
lThe role of producers is to convert energy into a form useable for other organisms

14. Producers
lMost producers are photosynthetic
(e.g. algae, mosses, diatoms, some bacteria, plants etc.) but some are chemosynthetic (e.g. hydrothermal vent bacteria)
(H2)

15. Decomposer
lAn organism that obtains energy by breaking down dead organic matter, including dead plants, dead animals and animal waste, into more simple substances
lExamples include: bacteria and fungi
L Interconnects all trophic levels since the organic material making up all living organisms is eventually broken down
lRole of decomposers is to return valuable nutrients to the system so they can be used again

16. Compare detritus feeders to decomposers:

17. Consumer lHeterotroph - “other” + “feed”
lAn organism that obtains its nutrition by eating other organisms
lPrimary consumer (herbivore) - eats producers e.g. sea urchin, copepod
lSecondary consumer (carnivore) - eats primary consumers e.g. wolf eel, herring
lTertiary consumer - eats secondary consumers e.g. sea otter, seal
lQuaternary consumer - eats tertiary consumers e.g. killer whale

18. Consumers
The role of the consumer is to transfer energy from one trophic level to the next.
Notice that consumers have different names, depending on what they eat:
Herbivores: plant eaters
Carnivores: meat eaters
Omnivores: eat plants and animals

19. Food Chains

20. Show energy flow through an ecosystem
Food webs
Show energy flow through an ecosystem
L An ecosystem’s trophic structure determines energy flow and nutrient cycling

21. Food webs

22. Trophic levels

23. Pyramid of biomass

24. Second Law of Thermodynamics
There is a tendency for numbers and quantities of biomass and energy to decrease along food chains.
The pyramids become smaller at the top because around 90% of the energy is “lost” between each level and only 10% is available in the body of the organism for transfer to the next level.

25. Energy transfer in a food chain: First law of thermodynamics

26. The end!