The Effects of Various Pollutants on Aquatic Pond Life.
 
 

Researched by Trevor G.
1998-99


  RESEARCH REPORT
  BIBLIOGRAPHY

Purpose

The purpose of this experiment was to determine the effects of various pollutants on a daphniaís heartbeat.

I became interested in this idea when I noticed articles in magazines and books saying that our water was becoming polluted and killing pond life.

The information gained from this experiment may help people understand the detrimental effects of pollution on pond life.


Hypothesis

My hypothesis is when the pollutant is added to the daphniaís water, it will slowly die due to intoxication. I think the gasoline or the weed killer will be the most toxic and kill the daphnia quicker. I think the control group, the ice melter, and the antifreeze will be less toxic.
I base my hypothesis on information I found on the Internet that scientists who had performed similar experiments put there.


Experiment Design:

The constants in this study were:
.
            -The type of daphnia.
            -The intervals between checking the daphniaís heartbeat
            -The size and type of rubber ring
            -The period of time between each trial

The manipulated variable was type of pollutant added to the daphniaís water.

The responding variable was the daphniaís death rate per minute.

To measure the responding variable I used my sight to count the daphniaís heartbeat.

Materials
 
Quantity Item description
1  Microscope
5  Petri dishes
5   16oz. jars
500ml. Aquarium water
25ml.  Gasoline
25ml.  Antifreeze
25ml.  Driveway ice melter
-  Tap water
25ml.  Roundup Weed Killer
75 Daphnia
1  Syringe
1  1 hour timer


Procedures

1. Gather materials needed.
2. Complete steps 3-8:
    3. Gather 5 glass quart-canning jars. (Make sure they are clean).
    4. Take one jar and add 500 ml. of water for your control group.
    5. In jar #2 add 5 ml. of gasoline and 500 ml. of water and mix well.
    6. For the third jar, add 5 ml. of automobile radiator antifreeze, and 500 ml. of water. Mix well.
    7. For the fourth jar, add 5 ml. of ìRoundup Weed killerî (diluted to application rate), and 500 ml of water. Mix well.
    8. For the last jar, add 5 grams. of dry driveway ice melter, and 500 ml. of water. Mix well.
9. Label all the jars with the pollutant they contain.
10. Set up the jars in a row in the work area.
11. Place a Petri dish in front of each jar.  Distribute 5 clean plastic rings in each Petri dish to act as corrals for the daphnia. Label the rings A, B, C, D, and E. Add 25 ml of liquid from jar #1 to Petri dish #1.
12. In a similar manner add liquid from jar #2 to Petri dish #2.  Repeat with 3, 4, and 5.
13. Set up a microscope with 40-power magnification in a safe place.
14. Set up a timer by the microscope.
15. Take an eyedropper and collect one daphnia and place it in the first plastic corral in Petri dish #1.
16. Repeat step 14 for the other four corrals.  Try to work quickly, but gently.
17. Place the Petri dish under the microscope.
18. Check daphnia ìAî for a heart beat for 15 seconds. Record whether daphnia is alive (heart beat can be seen) or dead (no observable heart beat), and repeat for the other four daphnia.
19. Set timer for 1 hour.
20. Repeat steps 15 ñ 18 for the other 4 liquids (pollutants.)
21. When the timer goes off observe the daphnia in Petri dish #1 in the same order (A, B, C, D, E), checking the daphniaís heartbeat for fifteen seconds each using the microscope.  Record ìaliveî or ìdeadî.
22. Reset timer for 1 hour.
23. Repeat step 21 for the other 4 liquids (pollutants) in the same order as in step 20.
24. Repeat steps 21 ñ 23 until a total of 8 observations have been made.
25. Discard daphnia and clean Petri dishes.
26. Repeat steps 11- 24 two more trials.
27. Average the results from all three trials.

Results

The original purpose of this experiment was to determine the effects of various pollutants on Daphnia.

The results of the experiment were the Gasoline and the ice melter killed all five daphnia each on hour one. The Antifreeze and the water were about the at the same pollutant level. The antifreeze killed one to two daphnia in each test. When the daphnia died on any of the pollutants between hour one, and hour two, I assumed it was because of natural causes, with the exception of the Gasoline and Ice melter. The weed killer (Round Up) killed most of the daphnia between hour 5-6, accept for trial two when four of them lived to hour eight. All three trials turned out very similar results.

 


Conclusion

My hypothesis was, when the daphnia come in contact with the pollutants; they will slowly die due to intoxication.

The results indicate that this hypothesis should be partly accepted. The gasoline was the most toxic pollutant. But the daphnia lived fairly well in the weed killer. The Ice melter was also very toxic. It killed them in the first hour. The daphnia lived the best in the antifreeze and the controlled group.  The results show that the hypothesis should be partly accepted.

Because of the results of this experiment, I wonder how much pollution in water is needed to actually kill daphnia. The amounts of pollution I added to the daphniaís water are probably much larger than you would find in water. So I wonder how much pollution is actually needed. If these large amounts killed them off so easily, how would a smaller amount affect them? I also wonder if the pollutants would have different effects on a different type of marine fish such as salmon.

If I were to conduct this project again I would use more pollutants. I would also do more trials and have more daphnia per trial. I would try to make the whole experiment more accurate so I could present better results. I would also try to take more time to do my experiment to make sure I did it right.


RESEARCH REPORT

Last year, I read an interesting statement in a magazine, and I realized that it was very important. It said, ì All of our pond life will slowly disappear as we continue to pollute our environmentî. I thought this was a pretty interesting statement, and it might be an interesting subject to research. I think my topic is important because it will show people what happens when they pollute and how it affects pond life. It will show them the overall detrimental effects of polluting.

Daphnia
Daphnia are very useful for testing pollution amounts in water. They are used as markers. They call this test the 50% marker. When they are placed in a body of water, if 50% or more of the daphnia die, the water is over polluted. If less than 50% die, the water is fairly clean. Daphnia are small fresh water crustacean. They are of the Chydoridae family. Daphnia are related to lobster, crab, shrimp, and crayfish. Daphnia are very advanced microscopic creatures. Like most crustaceans, they have a hard shell made of a chemical called chitin. Its shell is really made up of two pieces. They separate in the middle of the body. Daphnia have branched legs like structures that act as feet. They are actually antennae that come out of the top of the head. They are always moving. They move the daphnia through the water in short, quick, leaps. If you could magnify it enough, you could see that it moves backward like a person rowing a boat. Some daphnia are advanced enough to burrow in the mud on the bottom of puddles and ponds. Daphnia eat by using feather like feet to kick food in their mouth. Daphnia eat small aquatic plants. They also may eat pond life like newly hatched rotifers. 

Size
Not all daphnia are the same size. The largest species is Daphnia magna. It can grow up to four millimeters long. The smallest type is daphnia pulex, usually too small for the human eye to see. A basic full-grown daphnia is slightly larger than a newly hatched brine shrimp, and twice as large as a full-grown rotifer. 

Circulation
             For an advanced body, its circulatory system is very simple. A daphniaís heart beats very rapidly. This is because itís so small. The smaller the animal, the faster the heart beat. If you were able to hear a mouseís heart beat, it would be a high, humming sound, where an elephantís heart would sound like slow thuds. An interesting fact about the daphnia is that its heart is perfectly visible. You can even observe its heartbeat. A daphnia has no veins or arteries; instead, the blood inside of it travels through the empty spaces in the body and back to the heart. Like a reptile, daphnia are sensitive to heat. So there heartbeat is slower or quicker depending on the temperature of the water. If the water is warmer, its heartbeat increases. Lower temperature water has the opposite effect on it. A daphniaís blood is effected by oxygen rather than heat. 
If a daphniaís blood is rich in oxygen, it will appear to be clear, like the water around it. If itís  blood is not rich in oxygen, it will take on a red color like a humanís blood.

Discovery
Daphnia, along with other microscopic creatures, were discovered in a rain puddle. They were discovered by Anton Van Leeuenhoek. They were discovered in the late 1600ís. Leeuenoek was a Dutch microscope lens maker. When he first discovered them, he was shocked. But as he studied and took notes, he learned more about them and how they lived. He first called them animalcules. He also called them protists. He wanted to know more, so he started searching for more protists. He later discovered red corpuscle cells. He demonstrated how they worked in capillaries. He later discovered many other types of protozoa, and bacteria with his microscopes. The one thing that kept him going was interest for his work. 

Water Pollution
Pollution is a big threat to daphnia and other species. The definition of water pollution is the contamination of water. Pollution is a big threat to pond life because it can kill it off very rapidly causing the species to become endangered or possibly extinct. Some common pollutants that can be found in ponds or lakes are chemicals; bacteria, industrial wastes, carbonaceous material, pesticides, surface-active detergents, oil spills, plant nutrients, and even heat can become a problem. All of these are major threats to pond life.

In the future, I hope to research more on this topic.


BIBLIOGRAPHY

Carter, Joseph L.et al. "Life Science", Lexington, Massachusetts, GINN, 1971

 ìDaphnia FAQ fileî, [Online] available
http://www.rtop.com/features/daphnia-FAQ.txt 

ìPhysiological Ecology of Daphnia Magnaî, [Online] available
http://www.wku.edu/~stokes/zoology/225daphnia.html

Schwartz, George L., ìLife in a drop of waterî, Garden city, New York, The National History Press. 1970

Water Fleas-Zygote, ìEncyclopedia of the Animal Worldî. Vol.21, 1972. Grolier Inc.

 

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