1. Ecological pyramids and productivity

2. Activities Complete first and second page of Zoo assignment
Complete food chain and food web sheet

3. Ecological pyramids Represent trophic levels in an ecosystem
Do not show specific eating relationships
Detritivores and decomposers usually omitted
The length of the bar at each level of the pyramid shows the relative measurement of the trophic level in terms of numbers, biomass or energy

4. Pyramid of numbers
Shows number of organisms at each trophic level per unit area of ecosystem
Pyramid shaped is the most common, but sometimes the shape may be inverted or spindle shaped

5. Pyramid of biomass
Biomass is the amount (weight) of dry organic matter at a trophic level at a particular time
If biomass is measured only over a short period of time, pyramid may be inverted, as higher level organisms often take longer to build up biomass

6. Pyramid of energy Shows amount of energy INPUT into each trophic level
Never inverted. (why?)

7. Activities
Glossary: Ecological pyramid, biomass, pyramid of numbers, pyramid of biomass, pyramid of energy
Quick check pg 454

8. Productivity Rate at which chemical energy is produced in an ecosystem
Expressed in units such as “grams of organic matter per square metre per year”

9. Production: gross and net
Gross Primary Production (GPP) = chemical energy produced over a given period of time
R = energy that is used by the producers within their lifetime
Net Primary Production (NPP) = amount of energy available to consumers
NPP = GPP - R

10. In general, those ecosystems with the highest net productivity are those with the greatest producer biomass
More chemical energy stored in organic matter
More producer biomass
More photosynthesis
Other limiting factors of productivity:
Limiting factor
Why it limits
Temperature
Low = slower enzyme activity
Sunlight
Low = little radiant energy to convert
Nutrients
Low = stunted growth of producers
Water availability
Low = no growth of producers

11. Deep sea ecosystems
May survive on organic matter that floats down from surface-dwelling organisms
Few organisms live at these depths

12. Chemosynthesis No light = no photosynthesis
Chemosynthesis = bacteria use chemical reactions occurring at sea vents to produce organic matter

13. Activities
Glossary: productivity, gross primary productivity, net primary productivity, chemosynthesis
Quick check pg 458, pg 460