SF Bay Estuary Ecology Notes

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.

I. What is Ecology?

http://www.niot.res.in/

A.  Abiotic (Non-Living) Factors 1. Factors in SF Bay include:

•  Temperature •  Water •  Sunlight •  Wind •  Salinity:

•  varies from 0 to 33 parts salt per 1000 parts water depending on the location in the estuary.

•  0 is typically for freshwater rivers •  33 is for the saltiest parts of the ocean

•  Rocks and soil •  Natural Catastrophes: fires, floods, earthquakes

The Ecology of the SF Bay

B. Biotic (living) Factors 1. Normal biotic factors, including in the SF Bay, fall into the five kingdoms:

•  Plants, Animals, Protists, Fungi, Bacteria (Monera)

B.  Biotic (living) Factors - Continued 2. Organisms are classified as follows:

•  Producers- organisms that make their own food using photosynthesis (Ex: plants and phytoplankton)

•  Consumers-organisms that receive their energy from consuming other organisms (Ex: animals and zooplankton) herbivores-eat plants (Ex: Deer)

carnivores-eat herbivores and each other (Ex: Mountain Lion) omnivores-eat both plants and animals (Ex: Raccoons)

•  Decomposers -organisms that obtain their energy from non-living organic matter (Ex: earthworms and bacteria)

C. Human Impacts 1. Factors in SF Bay include:

•  Endangered or threatened plants and animals

•  97 species of endangered or threatened plants and animals use the Estuary during at least a part of their lives.

•  Diversion of Fresh Water •  approximately 50% annual flow of

fresh water is diverted for agriculture.

•  Waste and Run-Off •  From local industry (waste and trace

metals) •  From urban runoff (roadways and

gutters) •  Destruction of Tidal Marshes

•  85% of the tidal marshes have been destroyed for construction of homes, etc.

A. The Sun is the Source of Energy for Every Ecosystem 1. Producers convert the sun’s energy into chemical energy through a process called photosynthesis. 2. Equation

Carbon Dioxide + Water è Glucose + Oxygen��� (from the air) (plant sugar/food) (plant waste)

III. Energy in the Ecosystem

B.  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:

III. Energy in the Ecosystem

diatoms shrimp salmon sea lion

EnergySource Producers Primary

ConsumersSecondaryConsumers

Top consumers

Trophic level

B.  Food Chains and Food Webs 4. A food web is a diagram illustrating the flow of energy through an entire ecosystem.

5. Example:

III. Energy in the Ecosystem

*Arrows show direction of energy flow

C.  Ecological Pyramids -An ecological pyramid represents energy relationships among trophic levels.

1.  Pyramid of Energy

III. Energy in the Ecosystem

Ten Percent Rule: • A consumer gets energy from a producer, but only 10% of the energy in the producer that was consumed gets stored as energy in the body of the animal that eats it • 90% of energy in the producer is lost as heat or is used up by the body as it processes the organism that was eaten

C.  Ecological Pyramids 2. Pyramid of Biomass and Numbers

III. Energy in the Ecosystem

Biomass: The total mass of all the living organisms in an ecosystem

1. Suggest an explanation why there are fewer lions than zebras on the African plains.

IV. Questions to Consider

*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.

2.  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.

Grain100

Cow10

or

Grain10

Person1