Effects of Chlorine on Daphnia for Science Fair Projects

Chlorine: Toxic and Helpful?

Chlorine is a very helpful chemical, however, it can also be toxic in high concentrations. If you are interested in testing what chlorine can do to biological organisms at toxic levels then test it out on the daphnia. This project subject can be used to see if chlorine is a good pool pesticide as well as to see how it effects biology at toxic levels.

PURPOSE

The purpose of this experiment was to find out whether different concentrations of chlorine affect the survival rate of daphnia.

I became interested in this idea when I found out that you could see a microorganism's heart beating and experiment with them.

The information gained from this experiment could lead large companies, municipal water plants, and homeowners to learn that they are doing damage to the food chain. By polluting the environment with chlorine, you are killing daphnia, which feed the fish we eat.

HYPOTHESIS

My hypothesis is that as chlorine concentrations increase, the percent of daphnia survival will decrease.

I base my hypothesis on the fact that chlorine is dangerous to human beings. It is known to be fatal if swallowed or inhaled in concentrated amounts according to the manufacturers.

EXPERIMENT DESIGN

• The temperature of the water
• The amount of water
• The amount of daphnia tested
• The same kind of containers
• The same type of daphnia

MATERIALS

PROCEDURES

1. Prepare all of the necessary supplies and put the safety gloves on.
2. Make the dilutions by adding the prepared 1 ml of chlorine to the prepared 99 ml of distilled water in a graduated cylinder. That was the strongest solution.
3. Then add 10 ml of the previous solution to 90 ml of distilled water in a graduated cylinder. Thus, having the second strongest solution.
4. To make the third least potent solution, add 10 ml of the previous solution to the 90 ml of already prepared distilled water.
5. To make the weakest solution, add 10 ml of the previous to 90 ml of distilled water.
6. Get the dishes out and number them on the bottom one through five, five being the most lethal.
7. Pour 10 ml of the first solution into dish one.
8. Place 10 ml of the second solution into dish two.
9. Insert 10 ml of the third solution into the third dish.
10. Pour 10 ml of the third solution into the third dish.
11. Pour 10 ml of plain distilled water into the dish number five.
12. Place ten beads in each solution. Repeat step twelve until there are ten beads in each dish.
13. Then take the eyedropper and suck up one daphnia at a time placing them into one ring at a time until finished.
14. Check the daphnia every ten minutes with a microscope and see how many are still alive. (Their heart will stop beating if they die.)
15. Record the times as follows: Time 0=starting time
Time 10=ten minutes past
Time 20=twenty minute past
Time 30=thirty minutes past
Time 40=forty minutes past
Time 50=fifty minutes past
Time 60=sixty minutes past
If some of the daphnia do not die, douse them in a heavy concentration of chlorine and then flush them.
* First Solution is 1% potent
* Second solution is 0.1% potent
*Third solution is 0.01% potent
*Fourth solution is 0.001% potent

RESULTS

The original purpose of this experiment was to find out whether different concentrations of chlorine affect the survival rate of daphnia.

The results of the experiment were that chlorine reduced the survival rate of daphnia considerably. It reduced the number of living daphnia usually within five minutes.

CONCLUSION

My hypothesis was that as chlorine concentrations increase, the percent of daphnia survival would decrease.

The results indicate that this hypothesis should be accepted.

Because of the results of this experiment, I wonder if similar results would be seen with other microorganisms.

If I were to conduct this project again I would use other pollutants instead of chlorine. In my experiment I would do more than one trial with more daphnia per trial. 3rd party contributor