Sample Abstract of a 5th grade student project
HOW DOES WATER POLLUTION AFFECT THE HEART RATE OF DAPHNIA (Water Flea)? John Herr, and Judy Luedke (teacher) Valley Presbyterian School, 9200 N. Haskel Ave. North Hills, CA 91343
Daphnia magna (waterflea) is a fresh water crustacean found in lakes and ponds throughout much of North America and is an important element in the aquatic food chain. Experiments were developed to determine how water pollution from common household products affects the heart rate of Daphnia magna. Images of the Daphnia heart were viewed on a computer connected to a compound videomicroscope through an analog/digital converter. Daphnia were placed in single drops of pond water on depression slides and videotaped twice to record normal resting heart rates. Heart rates were determined by playing the digital videos in slow motion and dividing the number of beats by the elapsed time reported by the software. After an average resting heart rate was determined, one drop of 1.0% pollutant was added to each slide, bringing the final pollutant concentration to 0.5%, and the heartbeats were recorded at one, three, five and thirty minutes from the time of exposure. The procedure was replicated with a second Daphnia for all pollutants tested and the results were averaged. All of the pollutants tested made the heart rates decrease during the thirty minutes observed. After thirty minutes the heart rate went down 100% in ammonia and Draino, but only 51% in ethanol, and 21% in paint thinner. The greatest effect was observed with ammonia which killed Daphnia in 3 minutes, followed by Draino which killed the Daphnia 5 minutes. Ethanol reduced the heart rate 51% after thirty minutes while pant thinner reduced the heart rate only 21% during the same period.