1. SF Bay Estuary Ecology Notes

2. I. What is Ecology?
A. Definitions:
1. Ecology- The study of the interactions of organisms with one another and their environment.
2. Ecosystem-a self-sustaining collection of organisms and their environment.
3. Estuary-a partially enclosed body of water where fresh river water mixes with salty ocean water.

3. II. The ABC’s of Ecology
A=Abiotic Factors (non-living)
1. Factors in SF Bay include:
Temperature
Water
Sunlight
Wind
Salinity:
- varies from 0ppt to 35ppt depending on the location in the estuary.
Rocks and soil
Catastrophes: fires, floods, earthquakes

4. B. B=Biotic Factors (living)
1. Factors in SF Bay include:
Plants, Animals, Protists, Fungi, Bacteria
2. Organisms are classified as follows:
Producers- organisms that make their own food using photosynthesis
Consumers-organisms that receive their energy from consuming other organisms herbivores-eat plants carnivores-eat herbivores and each other omnivores-eat both plants and animals
Decomposers -organisms that obtain their energy from non-living organic matter

5. C. C=Cultural Factors (human impact) 1. Factors in SF Bay include:
Endangered plants and animals
30 species of endangered plants and animals use the Estuary during at least a part of their lives.
Diversion of Fresh Water
~50% annual flow of fresh water is diverted for agriculture.
Waste and Run-Off
Almost 200 industry sites dump wastes into the Estuary each year-including 300 tons of trace metals. Urban runoff contributes even more pollutants.
Destruction of Tidal Marshes
- 97% of the tidal marshes have been destroyed or altered.

6. III. Energy in the Ecosystem
A. The Sun is the Source of Energy
1. Producers convert the sun’s energy into chemical energy through a process called photosynthesis.
2. Equation:
Carbon Dioxide + Water = Glucose + Oxygen CO H20 = C6H12O O2

7. III. Energy in the Ecosystem
Food Chains and Food Webs
1. Consumers receive energy by eating producers or other consumers.
2. A food chain is a diagram showing the flow of energy through individual organisms.
3. Example:
diatoms
sea lion
shrimp
salmon
Trophic level
Source
Producers
1º Consumers
2º Consumers
Top consumers

8. III. Energy in the Ecosystem
Food Chains and Food Webs
4. A food web is a diagram illustrating the flow of energy through an entire ecosystem.
5. Example:
*Arrows show direction of energy flow
Figure 47-21

9. III. Energy in the Ecosystem
Ecological Pyramids -An ecological pyramid represents energy relationships among trophic levels.
Pyramid of Energy
Figure 47-16
10% rule:
Only 10% of energy can be transferred to the next energy level!
90% of energy is used by organism or lost as heat

10. III. Energy in the Ecosystem
Ecological Pyramids
2. Pyramid of Biomass and Numbers
Figure 47-16

11. IV. Questions to Consider
1. Suggest an explanation why there are fewer lions than zebras on the African plains.
*90% of energy is lost at each level so there
isn’t as much energy available for top consumers.
Also, it is easier to get food as a producer so population
numbers are higher.
More agricultural land would be available to provide food for the growing human population if humans did not eat meat. Explain why.
A person gets the same amount of energy from eating the same amount of either meat (cow) or grain. But due to the 10% rule, much more grain will be used if the person eats the cow for energy. Making more grain uses land and resources that could be available to feed more people.
Person 1
Grain 10 or
Cow 10
Grain
100