IOWA 4-9 SCIENCE PROJECT

TEACHER GUIDE for: GUPPIES, CYCLES, AND ECOSYSTEMS Steve Bartlett
ECOLOGY.695 Grades 7-9


CONCEPT OBJECTIVE:

Students will set up a balanced aquatic ecosystem and
monitor the water quality and animal/plant populations for a period of 20-30 days.


PROCESS OBJECTIVES:

Thinking skills developed in this cycle are predicting, investigating, experimenting and reporting.


TEACHER BACKGROUND:

This project should be carried out to help reinforce concepts in the water cycle, carbon-dioxide/oxygen cycle, and nitrogen cycle. The students should have some understanding of how these cycles operate. The idea for this project is for the students to work in teams to set up an aquatic ecosystem and observe the 3 cycles operating. Emphasis should be placed trying to create an ecosystem that can operate effectively without any human interference. Water quality can be checked by the students at various intervals during the project. The results should be kept by the students and some things could be graphed to show relationships but this is not totally necessary. Also there is a wide range of water testing that can be done and this may depend on what chemicals are available to the teacher and what water tests the students are capable of doing. The tests that are included here are the CO2 test, the dissolved oxygen test, and the nitrate test. Other tests that could be done are the ammonia test and the hardness test. Most tropical fish shops stock testing kits to test aquarium water. Also science companies sell a wide range of testing kits. I guess what you use depends on what your school can afford and how deeply you want to go into this part of the project.


MATERIALS:

Plastic 2 liter pop containers or homemade aquariums or other suitable containers, aquarium plants (elodea, hornwort, duckweed or other suitable plants, hay infusion or infusoria, snails, crayfish or other suitable scavengers, thermometers, ph meter or
ph paper, water testing equipment (hach kits or water testing kits from tropical fish shops


EXPLORATION:

Students should investigate the abiotic and biotic
components of the water cycle, carbon dioxide/oxygen cycle, and nitrogen cycle. They can use science reference books to create a drawing of each cycle showing all the relationships which exist within each of these cycles.


CONCEPT DEVELOPMENT:

Have the students design what they think is the perfect aquatic ecosystem that could survive by itself. Have them include all the abiotic and biotic things that would be necessary to keep the system going. What things are necessary to support each of the cycles? ( carbon-dioxide/oxygen, nitrogen, water). The students should fill out the plan sheet for their system and then get it approved by the instructor.


APPLICATION:

Students should construct their aquatic ecosystems with the materials provided. Two liter pop containers will work for the aquarium. They are lightweight, portable and the students can take them home when they are finished. The disadvantage is that to get water samples, you must pour out some of the water to test it. Also in a closed system, there is a limit to the time the guppies will survive because there is not an exchange of gases with the atmosphere, so the system may become polluted and not be able to cleanse itself. Small plastic containers may be purchased from science supply houses for around $2.00. Also if you can get a glass company to donate some glass for this project, you can easily construct your own aquariums using silicone sealer. Plants which can be used can be purchased from tropical fish shops include hornwort, elodea, duckweed and others that do not require a root system planted in soil or sand. Feeder guppies and feeder goldfish may be purchased from tropical fish stores fairly cheaply for less than $2.00/dozen. Snails and crayfish may be used for scavengers. A food source could be a hay infusion of microorganisms. Also available from fish shops is infusoria, a microorganism powder which if placed in water with hay, grass or some other food source will develop in about 48 hours with plenty microorganisms for the fish to eat. Pond water infusion could also be used. The following variables may be monitored by the students: temperature, ph, CO2, O2, nitrate. Instructions are included in the student packet for doing the carbon dioxide test, the oxygen test, and the nitrate test. Ph levels may be checked with a ph meter (expensive) or ph paper. Students can graph the results of these tests to see relationships as time passes. Water
testing should be done prior to introducing any plants and animals to the system. Then it can be done every day for a few days, then once every 3 or 4 days. Changes in the system should be observed by the students and recorded in their data table. New additions to the tank (births) and deaths should be noted. Odor, color, turbidity and other factors may be considered. The point should be made that plants and animals die even in a perfect system and this could happen in their aquarium.
QUESTIONS:
1. How successful was your guppy aquatic system? If not, what
would you change to make it better?

2. What are the limiting factors of your guppy population?

3. How was your guppy ecosystem like a real pond community? How
was it different?

4. Design another aquatic ecosystem which might run more
efficiently.


GUPPIES, CYCLES, AND ECOSYSTEMS

In this project your team will be given some fish (guppies) and a
tank. Your job is to set up a balanced ecosystem that will keep your fish alive for a period of time determined by your teacher without intervention. Your mini-ecosystem will be like the ecosystem of a pond. Just as in a full sized pond, the three major cycles we have studied will be going on in order to maintain a balance. In planning your ecosystem you must allow for these cycles. You will monitor your ecosystems periodically by observations and testing samples of the water for levels of oxygen, nitrogen, and carbon dioxide. You will also learn what pH means and how to check the pH of your water.
NOW ITS TIME TO PLAN YOUR ECOSYSTEM

CYCLES

OXYGEN / CARBON DIOXIDE CYCLE- In order to support this cycle
we will need to




Biotic items we will need are





Abiotic items we will need are




WATER CYCLE- In order to support this cycle we will need to





Biotic items we will need are





Abiotic items we will need are





NITROGEN CYCLE- In order to support this cycle we will need to






Biotic items we will need are





Abiotic items we will need are






Food Source for the fish?




Name of fish




GROUP MEMBERS__________________________________

This plan is approved_________ Date________
Teacher signature__________________________



GUPPY TANK DATA
NAME/S_________________________________________________MOD_______ ___SEC.______
DATE STARTED_________________________
FISH NAME/S ________________________ ___________________ ____________________

WATER ORGANISMS

DAY D/0 (ppm) D/CO2 (ppm) N2 (ppm) PH Odor Plants Animal

TESTING WATER QUALITY

NAME/S__________________________MOD_______________SECTION________ _
You have learned that an ecosystem is kept in balance by various cycles. The Oxygen/Carbon Dioxide Cycle takes the waste product, CO2 out of the system and puts O2 into the system. The WATER CYCLE purifies water. The NITROGEN CYCLE takes the waste products in the form of nitrates and nitrites
out of the system and makes them available to the plants. In a balanced pond ecosystem these cycles keep the oxygen level high enough to support the animal life and keep the carbon dioxide and nitrogen levels low enough so the animal life can survive. Today you will learn how to test the water for carbon dioxide (D/CO2). The levels for all of these will be entered in your chart in parts per million (ppm)

PROCEDURE FOR TESTING FOR CARBON DIOXIDE IN WATER

1. Fill the plastic test tube 1/2 full with water from your guppy tank. Use the special droppers to draw up a sample of your water.

2. Add 1 drop of Phenolphthalein indicator solution to the contents of your test tube.

3. Add the Sodium Hydroxide solution drop by drop. Count each drop as is is added. Continue adding drops until a light pink color forms and persists for 30 seconds. Remember to swirl the test tube after each drop is added.

4. Each drop of Sodium Hydroxide solution you added equals 5ppm of carbon dioxide (CO2).Multiply the number of drops that you used by 5 to find the ppm for the day.

SAFETY PRECAUTIONS !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

BOTH OF THESE CHEMICALS CAN BE DAMAGING TO THE EYES AND IRRITATING TO YOUR SKIN. THEREFORE, IT WILL BE NECESSARY FOR PEOPLE DOING THIS TEST TO WEAR SAFETY GOGGLES AT ALL TIMES INCLUDING DURING THE TIME THEY ARE CLEANING
THE EQUIPMENT AFTERWARDS.


Testing Water Quality: Nitrites and Nitrates

Too much Nitrite in the water is very harmful. It is caused by organic substances (fish excreta, food and plant residues). High values signal organic materials are not being broken down through the biological filter or by natural means. Most of the fresh water and sea water fish can tolerate a Nitrite content of 0.5mg per liter. Periodic checks of the aquarium water are necessary so that a safe Nitrite level is not exceeded. To detect Nitrite levels in water it will be necessary to purchase some water test kits from aquarium or pet shops. There are several companies which produce these products.
METHOD 1 (using TETRATEST NO2 kit available in most aquarium and fish shops. Other brands are available also)

1. Rinse the measuring flask or test tube with water from the
aquarium.
2. Put 5 ml of aquarium water into the flask.
3. Hold the dripping bottle (Tetratest #1) vertically above the flask opening and put 7 drops in.
4. Shake lightly
5. After 10 seconds add 7 drops of Nitrite #2.
6. Shake again
7. Leave standing for 2-5 minutes, then compare coloring of the liquid with the color scale. Read the measurement and record in your data table. The color scale printed on the cardboard box gives you adequate information about the Nitrite content of the water. In order to obtain a more precise measure you could use the Tetratest Colorimeter with the color wheel. For this project all that is really necessary to know is that a bright yellow color indicates low nitrite levels and a red to dark red color indicates high levels of nitrite.
8. After measurement, clean flask or test tube with tap water.

Method #2 (using Hach low range Nitrate test kit, Model NI-14, Cat. No.14161-00). Hach Company, P.O. Box 389, Loveland, Colorado 80539, Telephone: 303-669-3050, TWX 910-930-9038.Follow directions listed in the kit.


TESTING WATER QUALITY: DISSOLVED OXYGEN
(Using Hach dissolved oxygen test kit: Model ox-2p Cat. No.1469-00)

High Range Test Instructions

1. Fill the Dissolved Oxygen bottle (round bottle with glass stopper) with water to be tested by allowing the water to overflow the bottle for two or three minutes. To avoid trapping air bubbles in the bottle incline the bottle slightly and insert the stopper with a quick thrust. This will force air bubbles out.
If bubbles become trapped in the bottle in steps 2 or 4 the sample should be discarded before repeating the test.

2. Use the clippers to open one Dissolved Oxygen 2 Reagent Powder Pillow. Add the contents of each of the pillows to the bottle. Stopper the bottle carefully to exclude air bubbles. Grip the bottle and stopper firmly, shake vigorously to mix. A flocculant (floc) precipitate will be formed. If oxygen is present in the sample the precipitate will be brownish orange in color. A small amount of powdered reagent may remain stuck to the bottom of the bottle. This will not affect the test results.

3. Allow the sample to stand until the floc has settled halfway in the bottle, leaving the upper half of the sample clear. Shake the bottle again. Again let it stand until the upper half of the sample is clear. Note the floc will not settle in samples with high concentrations of chloride, such as sea water. No interference with the test results will occur as long as the sample is allowed to stand for four or five minutes.

4. Use the clippers to open one Dissolved Oxygen 3 Reagent Powder Pillow. Remove the stopper from the bottle and add the contents of the pillow. Carefully restopper the bottle and shake to mix.
The floc will dissolve and a yellow color will develop if oxygen is present.

5. Fill the plastic measuring tube level full of the sample prepared in steps 1 through 4. Pour the sample into the square mixing bottle.

6. Add PAO Standard Solution drop by drop to the mixing bottle, swirling to mix after each drop as it is added. Continue to add drops until the sample changes from yellow to colorless.

7. Each drop used to bring about the color change in step 6 is equal to 1 mg/L of dissolved oxygen (DO)

OTHER WATER TESTS

1. Ammonia ( test kits are available from fish shops and
companies like Hach.)

2. Ph ( Ph meters may be used or Ph paper)