1. By the end of this session I should be able to:
(a) define the term ecosystem;
(b) state that ecosystems are dynamic systems;
(c) define the terms biotic factor and abiotic factor, using named examples;
(d) define the terms producer, consumer decomposer and trophic level;
(e) describe how energy is transferred though ecosystems;
(f) outline how energy transfers between trophic levels can be measured;
(g) discuss the efficiency of energy transfers between trophic levels;
(h) explain how human activities can manipulate the flow of energy through ecosystems (HSW6b);

2. On the piece of paper in front of you there are 10 different ecosystems. Name as many as you can by labelling the pictures and adding the selection pressure that would have the biggest effect on the organisms living there.

4. What is lurking in your eyelashes?

5. Use your texts to complete the following
Key Word
Definition
Examples
Link across the spec
Ecosystem
Abiotic factor
Biotic factor
Producer
Consumer
Decomposer
Trophic level

6. What selection pressures does Ethan have to cope with
What selection pressures does Ethan have to cope with? Think biotic and abiotic factors.

7. Biotic  living / Abiotic  non living
Biotic factors that Ethan needs to consider

9. What limits the length of the food chain?

10. What limits length of food chain?
H1: Energetics
Availability of energy limits to 5-7 levels
Depends on:
NPP
energy needed by consumers
average ecological efficiency
H2: Dynamic stability
Longer chains less stable because:
Fluctuations at lower trophic levels magnified at
higher levels --->
extinction of top predators.
Microcosms - useful for such tests…replicate essential features of ecosystem. Control all variables except ones of interest
Get pix of 1.20

11. A food web is a branching food chain with complex trophic interactions
Species may play a role at more than one trophic level
Food webs can be simplified by isolating a portion of a community that interacts very little with the rest of the community

12. Biomass available at the next trophic level
About one order of magnitude of available energy is lost from one trophic level to the next
Biomass available at the next trophic level
How heterotrophs use food energy
Reason why food chains generally consist of only 3 or 4 steps
Energy loss in an ecosystem
Cayuga Lake
In NY

13. How can we calculate the amount of energy? each trophic level?
Consumers
(heterotrophs)
Ecosystem trophic structure model: Spatial pattern set by autotrophs
Decomposers blur the pattern
Predators link components, stabilize system
Producers (autotrophs) 13

14. How is energy lost between trophic level?
Lost in the transfer of light energy into chemical energy in photosynthetic organisms
Lost in the transfer from one consumer the next

15. Primary productivity Gross Primary Productivity (GPP):
total amount of photosynthetic energy captured in a given period of time.
Net Primary Productivity (NPP):
the amount of plant biomass (energy) after cell respiration has occurred in plant tissues.
NPP = GPP – Plant respiration
plant growth/ total photosynthesis/
unit area/ unit area/unit time
unit time

16. Primary productivity – marine ecosystems

17. Global variation in estimated NPP
Figure 9

23. Mr Moore set the homework on ‘increasing efficiency in the production of food by manipulating trophic levels’