[ Target Science | Lessons and Investigations ]
Creek Safari

Patricia Dung, Target Science Director
Esther Zack, Target Science Academic Director
(adapted from our UCLA Urban Safari)


PART A: THE LIVING ECOSYSTEM

Introduction:
What is here? What do we see in the riparian habitat that we can recognize as an ecosystem? On our "creek safari" we will attempt to discover what this complex system is comprised of and begin to get a picture of the riparian ecosystem.

Materials: (For each group) Procedure:
1. Select a spot by the creek that can be safely explored.

2. Divide into small groups. Within each group divide into subgroups:
a. What's underfoot? b. What's at eye-level? c. What's overhead? d. What's in the water?

3. Use the following tasks (where appropriate) to conduct your investigations. Record what you see and experience (write it down, sketch it, photograph it).

Creek Safari Tasks: Choose one or two of the following to do.

1. Look for signs of animals by the creek and in the water: tracks, homes, evidence of eating, fecal deposits, pathways. What do these signs tell you about who lives here? Do you see anything swimming in the water or clinging to rocks?

2. Look for signs of who eats whom/what. Try to determine the food chain in which this animal exists. Do the animals you have discovered live off of nature or human intrusions (garbage, pet food, etc.)?

3. Do you see any animal homes? Lift a rock, move a twig, turn over a leaf. What do you see? (Be sure you put what you moved back the way you found it.)

4. Be a bird-watcher: Where do you see them? What do they seem to be doing? What do they look like (color, shape)? Can you identify any of them? How many of each species do you see?

5. Be an insect-watcher: Where do you see them? What are they doing? Do you observe any division of labor going on? Can you influence their behavior by scattering food particles?

6. What do you see that is reflective of human impact? Do you see any harm or benefits from that impact?

7. Walk along the creek for 10 feet. List all the different species of plants you see. If you don't know their names, just count them. (This technique is called walking a transect.)

8. Use your sense of smell. What is the dominant smell in the area? What is it caused by? Is it natural or man-made?

9. Pick one plant or animal at your level to examine as thoroughly as you can. If it is an insect, you can put it in the bug box, but be sure to put it back when you are finished observing it. Sketch or photograph it. Why did you pick this item?

10. Sounds- Close your eyes. Listen to the sounds around you. Which one do you notice most? Why? Is it a sound from nature, or man's creation? If you have a tape recorder, record for a while. Play it back and see if what you focused on was what the tape recorder picked up.

11. Study a quadrant of the creek. The plot can be "staked out" using string and stakes or delineated with rocks and pebbles. Sketch a quadrant map and record the location and number of plants and animals using symbols. For example, Æ could indicate filamentous algae and * could represent minnows. It is not necessary to know the names of each and every living thing, but you could use identification/field guides to help identify them. What physical factors would influence the distribution of plants and animals? List them. Would predict differences in the organisms found in your quadrant at different times of the day? different seasons of the year?

12. Microorganisms in Creek Water
Collect samples of creek water from different locations along the creek. Be sure to collect filamentous algae, floating debris, floating insects, etc. Label each sample. "Feed" your sample by floating a small piece of wilted lettuce or adding 3 grains of rice, yeast, or oatmeal. Be careful not to drop in too much food as this will cause fermentation. "Feeding" will increase the densities of the microorganisms so that it is easier to observe them with a microscope.

Set aside your water samples in a warm, lighted spot out of direct sunlight.

Use a pipette or medicine dropper to take a sample from the floating "scum" on top of the water samples near the lettuce or other food. Examine under low power. You may see larger insect larvae, worms, and filamentous algae. When you find a microorganism, switch to high power to observe it better. You should see various types of diatoms, unicellular green algae, protists such as paramecia, etc.

Make detail sketches of what you observe. What are they eating? What is the food relationship in the microworld.

Wrap-up:
When you are finished with your safari, discuss your findings with the other members of your group (ground level, eye level, overhead). Then share your group findings on chart paper with the other groups when you return. Compare what you found with their experiences, noting similarities and differences. Share any photographs and or tape recordings you made also.

Extension:
Have the members of each group contribute to a mural depicting their discoveries on their safaris.


PART B: THE ABIOTIC PART OF THE ECOSYSTEM- Work in your larger group.

Introduction:
An ecosystem is comprised not only of living things, the biotic part of an environment, but also of the physical environment, the abiotic part of the environment. Some of the abiotic factors include the water, air, weather, and geological features found in a given area. Living things adapt to these factors or emigrate or die.

Materials: (For each group) Creek Safari Tasks: Choose one of the following to do.

1. Water Speed and Quality
Where is your relative location along the creek? Middle or lower reaches? Is the water moving swiftly or slowly. Lay a meter stick along the bank of the creek and float a leaf from one end to the other. How long does it take? Record this in mm/sec. Do this in other sections along the creek.

Look at the water. Is it murky, clear, or in between? Use pH paper to test how acid or basic the water is.

If available, use coliform bacteria kits to test for possible fecal contamination in samples of water taken in various places along the creek.

If available, use water quality kits to test for pH, relative amounts of ammonia, nitrates and dissolved oxygen. ( LaMotte: Pond Water Tour for elementary and LaMotte: Dissolved Oxygen, Metchek kits)

If you are near where the creek empties into the ocean, you might test for specific qravity, an indirect measurement of salinity, by using a hydrometer.

Record your results in chart form for different locations of the creek.

Is there a difference in water quality along the creek from head waters to the lower reaches?


2. Air Temperature
Take readings l meter (39.37 inches) above any of the following, if found in your study area:

Celcius Farenheit
open barren ground or soil: ____________ ____________
1 meter over the open creek ____________ ____________
10 cm. over the open creek ____________ ____________
open grass/weeds or shrubbery: ____________ ____________
creek under the shade of a tree: ____________ ____________


3. Relative Humidity
The relative humidity or relative moisture in the air can be measured by comparing the wet bulb thermometer reading with a dry bulb thermometer reading. Read the instruction sheet with the sling psychometer and determine the relative humidity in the following places of your study area.


dry bulb celcius wet bulb celcius Rel. Humidity
open barren ground: ____________ ____________ ____________
open grassy area: ____________ ____________ ____________
open creek: ____________ ____________ ____________
under the shade of a tree: ____________ ____________ ____________


How do plants affect the amount of moisture in the air? Why? How does standing or moving water affect the amount of moisture in the air?

4. Rocks, Soil, and Sediment
List the kinds of rocks in your study area. If there is a larger rock 4 inches or more, lift it up and see if there are living things under it or on it. Compare the shape of rocks in the creek with rocks on the land. Look at sediment in the creek with your hand lens and under the microscope. What is it composed of? Can you identify living and non-living components? Does the soil have components of the rocks you observed?

Wrap-up, Part B:

When you are finished with your abiotic observations and measurements, discuss with your group how the abiotic environment determines and affects the living things found in your area. Discuss how living things affect the abiotic environment. Chart the discussion on chart paper.


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