The Effect of Various Pollutant Concentrations on Daphnia

Researched by Rachel F.
2002-03

PURPOSE

The purpose of this experiment was to determine the effect of various pollutants and their concentrations on the survival of Daphnia magna.

I became interested in this idea when I went on a school field trip and learned about aquatic life.  On the trip we learned about water pollution and it’s effect on phytoplankton and zooplankton. 

The information gained from this experiment would help teach our society what pollutants we need to reduce to insure health for streams, rivers, ponds, and lakes.



HYPOTHESIS

My hypothesis was that the greater the concentration of pollutant the lower the survival rate would be. 

I based my hypothesis on a video called "Clean Water".  In the video it talks about biomagnification.  When a toxin is consumed and goes up the food chain the concentration of the pollutant increases, and while doing so each animal becomes more toxic.  This lead me to believe that the same thing would happen when the daphnia are subjected to increasing concentrations of pollutants.



EXPERIMENT DESIGN

The constants in this study were:

  • Amount of daphnia in each petri dish during each trial
  •  Amount of water used in each petri dish during each trial
  • Size of petri dishes
  • Type of daphnia
  • Test procedure
The manipulated variable was the type of pollutant and the concentration used.

The responding variable was how many daphnia survived the pollutants. 

To measure the responding variable I used a jeweler’s loupe to examine the daphnia’s heartbeat and movement over different periods of time. 



MATERIALS
QUANTITY
ITEM DESCRIPTION
150  Daphnia magna
365 ml Tap Water
1 Jewelers Loupe
1 ml Antifreeze
1 ml Roundup Weed Killer
1 ml Clorox
10  Petri Dish
4  Pipette



 PROCEDURES

1. Make the twelve mixtures of pollution and water at the different concentration percentages
A.) Pipette 1.0 ml toxin into graduated cylinder 
B.) Add 99.0 ml H20 to graduated cylinder
C.) Label beaker as 1.0% toxin
D.) Take 10.0 ml of 1% toxin put in clean graduated cylinder
E.) Add 90 ml of H2O to gaduated cylinder
F.) Label beaker as 0.1% toxin
G.) Take 10 ml of 0.1% toxin put in clean graduated cylinder
H.) Add 90 ml of H2O to graduated 
I.) Label beaker as 0.01% toxin
J.) Repeat A-I with next toxin
K.) Repeat A-I with all remaining toxins 
2. Use the pipette to pick up twenty daphnia and put in Petri dish, separated at equal distances 
3. Check the daphnia to make sure all are alive before starting experiment
4. Dab the water near daphnia with a tissue to remove excess water 
5. Put 15 ml of pollution and concentration in Petri dish
6. Let the daphnia sit in solution untouched for 10 minutes
7. Check the daphnia with a jewelers loupe to examine their heart beats
8. Then record the amount of daphnia with heart beats and the amount without after every 10 minutes for 80 minutes, then check after 24 hours
9. Repeat steps 2-7 for the other 8 trials with a different pollution and concentration
 RESULTS

The original purpose of this experiment was to determine the effect of various pollutants and their concentrations on the survival of Daphnia magna.

The results of the experiment were that Clorox bleach killed the daphnia faster than the other two pollutants, and the higher concentration of the pollutant the lower the daphnia survival rate. 

See the table and graph below.



RESULTS

The original purpose of this experiment was to determine the effect of various pollutants and their concentrations on the survival of Daphnia magna.

The results of the experiment were that Clorox bleach killed the daphnia faster than the other two pollutants, and the higher concentration of the pollutant the lower the daphnia survival rate. 

See my table and graph



 CONCLUSION

My hypothesis was that the greater the concentration the lower the survival rate.

The results indicate that this hypothesis should be accepted. 

Because of the results of this experiment, I wonder if different pollutants would produce the same results.  I also wonder if they would turn out different if I used different test organisms.

If I were to conduct this project again I would have done more trials and used more pollutants.  I also would have liked to have used different percents of pollution in my trials.  To tell which pollutant was most toxic I would really have to test it on another animal, because there might be pollutants that only affect daphnia, and not other species.


Research Report

Introduction

Water is our most important natural resource.  Without it the world as we know it would not exist.  Water nourishes all the living organisms on out planet.  That is why we need to stop polluting, and try to keep water clean.  There is only so much useable water in the world.

Arthropods

There are many different species of arthropods.  All the adults have two things in common; they all have jointed legs and bodies, and external skeletons.  Some arthropods have thick external shells like crab, and some have delicate transparent ones like daphnia.  As the animal grows it molts its skeleton which is replaced.  The arthropods are separated into five classes, which are millipedes, crustaceans, centipedes, spiders and insects.  The crustaceans are then divided into two groups.  The small group consists of fairy shrimp, daphnia, and brine shrimp.  The large group consists of crab, snow bug, crayfish and lobster.  Almost all crustaceans live in water, and breath with gills.  The young are usually developed from fertilized eggs.

Daphnia

Daphnia, also known as water fleas, are an important part of nature.  Because of their fast reproductive system they are basic food to marine, and freshwater fish.  Daphnia reproduce every 2-3 days, and one can reproduce about 13 billion babies in 60 days.  The babies are kept in an egg sack with embryos visible in the brood.  A brood is the place where the eggs are kept and is located right above the rear of the abdomen.  There are two kinds of eggs: thin-shelled ones which are produced during the summer and do not require fertilization by the males, and thick-shelled ones which are produced during the winter and do require fertilization by the males.  During the cold winter days the eggs do not hatch, but wait until warmer weather.  If the eggs are kept at room temperature then the batch will turn out with mostly females.  If the weather conditions are adverse, then the batch will consist of mostly males.  The males are recognized by their straight intestinal tubes.

Daphnia live in shallow water, usually ponds, lakes, or streams.  They are usually found close to the surface of the water, near vegetation, and away from currents.  Ponds with barnyard drainage, pools by dumps or swamps are an ideal place to find daphnia.  In a good area thousands can be found.

Freshwater daphnia thrive on Bacillus coli, Euglena, Chilmonas, and small green algae.  Daphnia magna are about 4 mm in size, and daphnia plutex are microscopic. They have a delicate transparent oval shaped shell.  Their eyes are a single compound and they have two antennae.  With many beats of their antennae down they will move up.  Without moving their antennae at all they will slowly sink.  Daphnia move in constant jerky movements.  Their internal body is clearly visible with a 10x lens.  The heart can be observed by the depressed or welled sides of the daphnia. 

Water Pollution/Clean Water 

Water is used for everything, from cleaning clothes, to watering the grass, to drinking.  Nothing can live without water, since every living organism needs it to survive.  Water covers over 70% of the earth’s surface, but out of that only 3% is suitable for drinking and irrigation.  Out of the 3% suitable for drinking and irrigation 75% of that is frozen in glaciers and ice caps.  That leaves only about 1% of the world’s water for human needs.

Water pollution is a large problem of the industrial life style.  It is found all around the world.  The majority of the world does not have safe clean drinking water.  Scientist believes that the availability of fresh water is one of the largest problems in the world.  Bad water is spreading disease all over Africa, Asia, and Latin America.  Some examples of water born diseases are dysentery, yellow fever, cholera, and malaria.  More than a million people in developing countries are affected by polluted water.  Unsanitary water is the cause of 3/4 of the world’s diseases.

When water is used as irrigation on crops and runs off into rivers it takes with it all the herbicides, and pesticides that were used on the crops.  Chemicals in bodies of water are bad because of biomagnification.  Biomagnification is the increase of chemical concentration, as it goes up the food chain.  Chemicals such as pesticides, are taken in by microorganisms, then eaten by fish, then the fish is eaten by another animal, and so on.  As the pollutant goes up the food chain the concentration increases with every animal, and each is made more toxic than the last.

Oceans get a lot of pollution, such as sewage, garbage, and untreated sewage from ships and barges.  One of the largest threats to aquatic life comes from plastics.  Littered plastics cause over 2 million deaths to sea birds, and over 100,000 deaths to marine mammals.  Many sea turtles mistake plastic sacks for jelly fish, and birds mistake plastic pellets for food. 

Chesapeake Bay is the largest estuary in the U.S.  An estuary is a water passage where many different rivers meet.  Estuaries get lots of pollution from sewage plants, urban and suburban run off, agricultural run off, and toxic waste.  This is causing the population of fish and crab to drop.

Antifreeze

Antifreeze is a liquid that protects an automobile’s cooling systems.  The antifreeze helps keep the vehicle from over heating or freezing.  It may contain ethylene glycol, diethylene glycol, propylene glycol, or sodium nitrite.  The ingredients are considered toxic and poisonous to animals when consumed. 

Clorox Bleach

Bleach is a household item that is used for whitening and softening laundry. Bleach is also used for other household chores like cleaning the kitchen, or washing the bathroom floor, or cleaning mildew stains from the exterior of the home.  It contains the ingredients Sodium Hypochloride, sodium hydroxide, and surfactants.  This product is very dangerous if consumed.  Clorox is one of  the many brand names of  bleach.

Roundup

Roundup is an herbicide used by farmers and  homeowners in their yards to get rid of any unwanted plants.  It can be harmful to animals and can run off into streams and rivers.  Some of the chemicals are biodegradable, but not all.  Some of the non-biodegratable chemicals can stay harmful for long periods of time.  If an organism consumes the toxin it will then be contaminated.

Summary

Humans would not exist without water.  Water is vital for all living things.  There is only a certain amount of water in the world.  If we pollute it now we are only hurting our future.

BIBLIOGRAPHY

"Antifreeze." January 4, 2003
<http://state.ga.usdur/p2ad/hhw/auto.pdf>

"Chemical of the Week Ammonia, NH3."November 13, 2002
<http://www.ask.com/mean/metaAnswer.asp.htm>

"Clean Water." Schlessinger Video Productions. 1993

Knapps, Brian. Nitrogen and Phosphorus. CT: Danbury, 1996. pp. 12-14

Krupinski, Marty. "Environmental Storm Water Management Diversion." December 8, 2002 
<http://www.norfolk.va.us/publicworks/stormwater.htm>

"Water Pollution." October 16, 2002 <http://Encarta.msn.com/Encarta/refpages/RefArtical.aspx?refid=761572857.htm

ACKNOWLEDGEMENTS

I would like to thank the following people:

  • Mr. Newkirk for helping me with everything, especially correcting my writing and getting my daphnia.
  •  My Mom and my Dad for all the support and taking me to and from after school classes.
  • My friend for all their support and encouragement.
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