Interactions - continued
Material from: page 88 - 105, Enger & Smith

1.  Review: Table 5.1 - Roles in an Ecosystem.
Trophic = eating

2.  Decomposers?

• Use nonliving organic matter for energy  & raw materials
• Sources of non living organics
• Shedding (hair, leaves)
• Excretion (urine, feces)
• Death of organism
• VERY important for recycling
• Who:  small animals, fungi, bacteria

2.  Keystone Species

• critical role in maintenance of specific ecosystem
• Examples
• Prairies: grazers (bison)
• Eat primarily grasses, other small plants left, biodiversity higher with bison than without
• Create wallows: disturbed sites for other plants
• Prefer burned area, create a patchwork
• Marine subtidal (sea otters)
• Eat sea urchins
• Sea urchins eat kelp
• No otters -> too many urchins -> kelp lost

3.  Figure 5.25:  Biomass & Energy: a pyramid represents the relationship between each trophic level

4.  Figure 5.26.  Energy Flow in Ecosystems: Each transfer looses energy to entropy

5.  Figure 5.27.  Food Chain: How many trophic levels from plant to human?
1 - primary producer
2 - grazer (1st consumer)
3 - predator (2nd consumer
4 - predator (3rd consumer)
5 - predator (4th consumer)
6 - top predator (5th consumer)

6.  Figure 5.28.  Food Web: Actual energy movement through ecosystems is a very complex web, not a strait line relationship.

7.  Review:ecosystem = biotic + abiotic

8.  Carbon Cycle: see Figure 5.29CO2 & O2 cycled

9.  Nitrogen Cycle:  follow from source to sink

10.  Phosphate Cycle:  source to sink and biological components
11.  What happens when too many nutrients wash down the watershed to the sea?  
12.  On your own

• What happened as a result of phosphate mining on Nauru?
• Analyze an aquarium as an ecosystem.  Identify the major abiotic and biotic factors.  List members of the producer, primary consumer, secondary consumer and decomposer trophic levels.