The Effect of Bleach on the Survival Rate of Daphnia
Student Experimenter

Researched by Lauren G.
2004-05


PURPOSE

The purpose of this experiment was to see the survival rate of daphnia exposed to bleach.

I became interested in this idea because, I know how dangerous bleach is to our environment as well as us, if someone eats a polluted fish. We are in danger of poisoning the world, including ourselves. Water pollution is something I’ve been interested in for these reasons and many more.

The information gained from this experiment could help humans to see that we are in big danger if we don’t stop polluting the water, and hopefully would explain to them some of the items or “necessities” that we use in everyday life are extremely dangerous to our world.

HYPOTHESIS

My hypothesis was that the bleach would kill the daphnia within twenty minutes, at almost any concentration.

I based my hypothesis on the fact that bleach is considerably dangerous to humans. Daphnia, more than likely, are affected in a far worse way.

EXPERIMENT DESIGN
  • The constants in this study were:
  • The temperature of water
  • The light each daphnia was put under
  • The species of daphnia
  • The experimental procedures
  • The amount of daphnia in one dish

The manipulated variable was the concentration of bleach.

The responding variable was the survival rate of daphnia.

To measure the responding variable I observed the daphnia for gill movement. If the gills weren’t moving, I counted them as no longer living...

MATERIALS  

QUANTITY
ITEM DESCRIPTION
16 Petrie Dishes
60 Daphnia
8 ML Bleach  
1192 ML Water
1 Eye Dropper
7
 200 ML Beakers
1 100 ML Graduated Cylinder
1 1 Liter Beaker

See my graphs  
PROCEDURES

1. Get together the sixteen petri dishes divided in to four quadrants, a one thousand ML beaker, a one hundred ML graduated cylinder, seven two hundred ML beakers.
2. Make sure all these items are clean. If they aren’t clean follow the sub steps bellow.
A. Get a wet paper towel and clean off the bottom of the item.
B. If it still looks dirty after you clean off the bottom of the dish then just, rinse the item(s) several times under warm water.
C. After rinsing six to seven times, use a paper towel as a little scrubber. (You shouldn’t need soap)
D. Then dry the items with a dry paper towel.
3. Get out daphnia and put five in each quadrant using the eyedropper. (Put a drop of water in with each daphnia or they’ll die before the experiment is over!)
4. Fill the one Liter beaker with water, be sure that the water temperature at 20 degrees.
5. Pour 92 ML of water into a 200 ML beaker.
6. Add eight ML of bleach into the same beaker creating 8% of bleach. Label it ‘8%’.
7. Then, pour fifty ML of the mixture into the graduated cylinder.
8.  Add fifty ML out of the one thousand ML beaker into the cylinder.
9. Pour the contents of the graduated cylinder into another beaker then back into the graduated cylinder and then back into the beaker again. (To mix it) Label this beaker 4%
10. Repeat steps 7-10 four times, but put the following labels on in the exact order: 2, 1, .5, .125.
11. Place the Petri dishes with the daphnia on the table in two rows of two.
12. With the first two daphnia dishes to the left, just put in three ML of water in each quadrant totaling at 24 ML of water.
13. Repeat step thirteen except use all of the mixtures in the beakers that you earlier made.
14.Check each Petri dish every ten minutes for 90 minutes.
15. Record the number of daphnia that are still alive in each dish.
 
RESULTS

The original purpose of this experiment was to test the survival rate of daphnia against bleach.

The results of the experiment were that bleach killed daphnia quickly at low concentrations and at an even faster pace at high concentrations.
   
See the table and graph below.

CONCLUSION

My hypothesis was that the bleach would kill all of the daphnia, even at the lowest concentration, within 20 minutes.

The results indicate that this hypothesis should be accepted.

Because of the results of this experiment, I wonder if daphnia are as vulnerable to bleach if they’re in the wild.

If I were to conduct this project again, I would be more organized about my whole experiment, and check on the daphnia more often.

RESEARCH REPORT

Introduction
This report is about water pollution, even if no one gives a care at all about sea life, water pollution is dangerous to them too. Water pollution pollutes fish, microorganisms and other sea life. If a fish was directly intoxicated it would polluted, actually even if a microorganism that was intoxicated and the fish ate it the results wouldn’t be very different, the fish was caught and boiled, roasted or BBQ they’d be also be poisoned. No matter how minimal the poison, the effect isn’t a good one.

Water Pollution

What Water Pollution Is
Water Pollution is a common type of pollution that happens often. Trash is thrown in a river, or raw sewage gets into the ocean. Landfills may slide in a lake or river and kill and/or intoxicate millions of fish, microorganisms, sea mammals, and many more.

Causes for Water Pollution
Water pollution has many causes. Some people just throw trash directly into the water, or sewage will find it’s way to the ocean. Sometimes landfills near lakes or rivers can just slide into the water because of the weight and just collapse.  Pollution can also be washed out through the gutters. Oil is an excellent example of this. Like, if there’s a leak in a car’s gasoline tank, and leaves a puddle, especially in rainy places like Seattle, there’s a high chance of it getting washed out into the ocean and killing or, possibly, poisoning fish.

Daphnia

What Daphnia Are
Daphnia are freshwater zooplankton. They, being zooplankton, most of the time just float with the current. that are often used in lab experiments. This is most likely because it’s easy to see whether they’re alive or not, being nearly transparent.

Appearance
Daphnia are about .2-.3 Millimeters long and have a helmet-like head. They’re also transparent, or very close to being so, one could see right through them. It is also easy to see their heart beat. They have a tail that helps the daphnia move up and down. Their stomach is also visible, with their transparent body. They’re eye looks like a big black dot the eye is also the brain and the nerve.

Uses For Daphnia
Daphnia are primarily used for experimental purposes, but there are other uses for them. Daphnia are good bait for freshwater fish like trout, but only if they’re in clusters. If they aren’t then it’s impossible to get them attached to.

Daphnia Environment
Daphnia are fresh water zooplankton. Their general environment is in fresh water pounds, lakes, rivers, and so on. Daphnia eat bacteria so it’s often that you’ll find them in places like a pound that has mold or an unclean stream. Daphnia are actually located in Europe as well as North America. Daphnia are also practically invisible in lake water because the daphnia are usually either semi-transparent or the color of the lake water.

Species of Daphnia
There are around 135 species of Daphnia in North America and around 800 around the world, though most species are similar to another.

Summary

Water pollution is a dangerous thing for human beings, and the environment. Water pollution happens in many ways. Daphnia are small creatures that move around, live in lakes and ponds, and are often used for experiments or fishing.
BIBLIOGRAPHY

Clare, John. “Daphnia: An Aquarist's Guide.” http://www.caudata.org/daphnia/.  12/1/04.
 
Cornell University/Pennsylvania State University. “Environmental Enquiry Using Daphnia.” <http://ei.cornell.edu/toxicology/bousga/daphnia>. 11/26/04.

Orlans, Barbra F. “Animal care: From protozoa to small mammals.” 1977. Pp. 95-97.

Schuman, Kai. “FAQ – Prototype.” Daphnia. <http://ee.pax.edu/devidr/discus/artcas/daphnia>. 11/28/04.

Tulis, Larry. “Discovering Daphnia.” 9/01/2001.  Pp. 50-54.
 

ACKNOWLEDGEMENTS

I would like to thank the following people for helping make my project possible:
  •  My mom for driving me to the school so I could conduct my experiment and for buying the items that I’d use for it.
  •  My Soar teacher for helping me out with the daphnia

Top of page

Menu of 2004-2005 Science Projects

Back to the Selah Homepage