Researched by Charlie Ann G.
2003-04

• PURPOSE 
• HYPOTHESIS 
• EXPERIMENT DESIGN 
• MATERIALS 
• PROCEDURES 
• RESULTS 
• CONCLUSION 

• RESEARCH REPORT 
• BIBLIOGRAPHY 
• ACKNOWLEDGEMENTS 

• ABOUT THE RESEACHER 

Introduction
One of the most important human needs is the need for clean water.  Water pollution affects the environment in many harmful ways.

Daphnia
Daphnia, also known as water fleas, are crustaceans, a group of arthropods, found mostly in freshwaters. They range in size from 0.2 to 0.6 millimeters.  Daphnia are used widely as test organisms, because their clear outer shell enables researchers to easily observe the organs and other internal body parts of this microscopic animal.

Daphnia are used for two main things. As a bio-indicator, their translucent bodies allow a scientist to tell if a chemical has an effect on their heart rate. A scientist could also measure the toxicity of a chemical in the water by observing changes in the heart rate of a daphnia. Daphnia are also used as fish food because they are easy to grow and reproduce quickly.

Daphnia are very proliferate. Four days after they hatch, daphnia start reproducing. Most populations consist of all asexual females, however lack of food and poor conditions cause females to lay male eggs.  When male eggs are produced, sexual reproduction begins, and females lay resting eggs, similar to those of the brine shrimp. Every batch of eggs that a daphnia produces is called a brood. A female’s first brood usually consists of 4-22 eggs, but as they age, a daphnia’s brood can consist of over 100 eggs. The average number of broods a female produces in a lifetime is six, but some females may lay up to 25.

The daphnia’s body can be divided into three parts: the posterior abdomen, the middle thorax, and the anterior head. The posterior abdomen and the middle thorax are enclosed in the carapace, or a “double fold of body wall”. The daphnia’s head extends away from the carapace, and is bent downward, or ventrally. The carapace “folds along the dorsal midline” and forms a valve on each side of the body of the daphnia.  This is why the carapace is also called the bivalved -- meaning two-valved -- carapace. The organ that moves the animal, is its second antenna.  It moves up and down, and the daphnia is transported up near the surface of the water, and back down, though very jerkily. These movements look like the daphnia is jumping, so they are nicknamed water fleas.
 

Water Pollution
Pollution is very harmful to most all living things. It damages the environment and kills already endangered plants and animals.

Water pollution is the “contamination of streams, lakes, underground waterways, bays, or oceans by substances harmful to living things”.  Water pollution can be divided into eight main categories: petroleum products, pesticides, herbicides, heavy metals, hazardous wastes, excess organic matter, sediment, and infectious organisms.

Petroleum products, which are used for fuel and manufacturing plastic, are extremely harmful to living organisms. Most spills of petroleum  are accidental ship spills, but when contacted with animals, petroleum can damage feathers, fur, and even cause the death of animals.

Pesticides and herbicides, the chemicals used to kill unwanted animals and plants, can be collected in rainwater runoff and taken into streams.  Some pesticides and herbicides are biodegradable, which means they can decay and become less or non harmful, but some pesticides and herbicides are non-biodegradable, and will stay toxic. When an animal 11consumes something contaminated with non-biodegradable chemicals, the chemicals get absorbed into the body tissues of the animal, and if another animal (or person) consumes the contaminated animal, the chemicals are passed on. It keeps going through the food chain, and each step up the food chain the concentration of the non-biodegradable chemical gets larger and larger.  Lots of drinking water is contaminated with pesticides. More than 14,000,000 people in the United States alone drink water with pesticides in it, and an estimated 10% of wells have pesticides in them.

Hazardous wastes are chemical wastes that are toxic, reactive, corrosive, or ignitable. If used improperly, hazardous wastes can pollute water supplies. A class of chemicals called PCB’s that were used in electrical equipment can “get into the environment through oil spills can reach toxic levels as organisms eat one another.”

Excess organic matter, or fertilizers and other things used to make plants grow better, and faster, can sometimes get into water. When these chemicals first reach the water, they promote the growth of algae, and other plants found underwater, but when the algae and other plants die, microorganisms, such as plankton or daphnia, decompose them.  While decomposing, these microscopic animals consume unusually high amounts of oxygen, making the oxygen level in the water dangerously low.  When this happens, animals that are dependent on oxygen die. “This process of depleting oxygen to deadly levels is called eutrophication”,  according to Encarta Encyclopedia, “Water Pollution”.
 

Specific Pollutants
Bleach is a chemical that makes any material whiter or brighter.  The type of bleach used in this experiment is called sodium hydroxide, and it is used for household cleaning. It is very harmful to any organism, but is very easy to get into an aquatic environment because when people clean their sink, for example, bleach goes down the sink and into a nearby body of water, killing many of its inhabitants.

Ammonia is a “colorless alkaline gas made up of one part nitrogen and three parts hydrogen, and is very soluble in water. When mixed with water, a chemical called ammonium hydroxide. When ammonia is dissolved in water, it is reactive with many other chemicals. Ammonium hydroxide “neutralizes acids and forms the corresponding ammonium salts.” So when mixed with other chemicals, which frequently happens, ammonium hydroxide can become extremely toxic, and deadly to aquatic animals.

Vinegar, a substance used widely as a food preservative, is mostly made of Acetic Acid, a substance which gives vinegar its sour taste. Acetic acid is a clear liquid with a stinging odor, and when not diluted by water, can cause severe burns. It is also used to make rubber, and is used widely as a solvent. Acetic acid in vinegar is very harmful to many environments, including aquatic ones.
 

Summary
Water pollutants are extremely harmful to all organisms, let alone the water itself. People drink water that has had toxins in them, so any little bit of water pollution can lead to the harm of other humans.

Armbruster, David C. “Ammonia” World Book Encyclopedia. 1998

“Crustacea”. 11/21/03. <http://www.orion1.paisley.ac.uk/cources/Tather/biomedia>

“Daphnia”. 11/21/03<http://www.selah.k12.wa.us/LINKS/daphnia.html>

Fox, Richard. Daphnia Magna. 1994, <http://www.science.lander.edu/rsfox/daphnia.html>

 Kai Shumann. “Daphnia FAQ-prototype”.12/12/03. <http://www.ee.pdx.edu/~davidr/discus/articles/daphnia.html>

McLaughlin, P.A. “Water Flea” World Book Encyclopedia. 1999

Needles, Howard L. “Bleach” World Book Encyclopedia.  1998

Oetinger, David F. “Vinegar” World Book Encyclopedia. 1998

Orlans, F. Barbara. Animal Care From Protozoa to Small Mammals. Canada: Addison-Wesley Publishing Company, 1977. pp.

“Water Pollution.” Microsoft Encarta Encyclopedia Deluxe.  2001