2005 Young Naturalist Awards - Environmental Effects of Industrial Run-off on Daphnia magna

Mauree Environmental Effects of Industrial Run-off on Daphnia magna

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Mauree with a sample in the lab

For the traditional part of my research this year I tested the water for phosphate, nitrate, ammonium nitrate, pH, dissolved oxygen, and total and free chlorine. I collected water samples at a total of seven locations. At each site I collected four two-gallon containers of water. I collected the water at both the entry and exit points of the creeks. Four different locations were required for Spring Creek. This was because there are three entry sites for this creek and one exit point. Brush Creek had only one collection site because it originates on the IAAAP, and, due to strict security measures after September 11, I was unable to obtain a sample at this entry site. I collected the water samples by lowering a metal bucket down into the creek with a rope. I made sure that no sediment was being brought up from the bottom of the creek because this would contaminate my sample. All of the samples were collected and tested within a six-hour period. I gave each sample a number: Spring Creek entering, 1-3; Spring Creek exiting, 4; Brush Creek exiting, 5; Long Creek entering, 6; and Long Creek exiting, 7. Immediately following collection, I tested the water samples for phosphate, nitrate, ammonium nitrate, pH, dissolved oxygen, and total and free chlorine. I also documented the temperature of the water at each of the test sites. The water tests were conducted in accordance with the standard procedures provided with the HACH water test kit.

For the non-traditional part of my research, I conducted two experiments using Daphnia magna. Before conducting any experiments using Daphnia magna, age controls were set. This was to ensure that the Daphnia magna were all the same age and that some of them would not die from old age at the beginning of the experiment, because this would alter my results. The age controls were set by placing individual adult Daphnia magna in plastic cups filled with spring water. The Daphnia magna were allowed to reproduce, and their offspring were then used in the experiments. The Daphnia magna were fed every week with liquid invertebrate food.

The lab setup

The purpose of the first experiment was to examine their population growth, heart rates, and reflex quality. To begin this experiment, I filled a total of eight plastic aquariums with a designated type of water (Site 1, 2, etc.). The eighth aquarium was for the control, and spring water was used for this type of water. Then I added five age-controlled Daphnia magna to each of the aquariums. Every day I counted the populations and checked the pH and temperature. Every other day I documented the Daphnia magna's heart rate and eye reflex, and also fed the Daphnia magna with the liquid invertebrate food. I monitored their heart rate by examining the Daphnia magna under a microscope and counting the beats per 15 seconds; this was then converted to beats per minute. In order to insure that the microscope's stage would not heat up, causing the Daphnia magna to become stressed, I changed the microscope's light source to a glass rod, bringing in light from the room, which is cool light. I measured their eye reflex by turning off the original light source and moving another light source (a flashlight) around the microscope 180 degrees and giving a rating of: 1) no reflex, 2) an incomplete reflex, and 3) perfect reflex. I then conducted a second trial, using water from the same collection times. Both trials lasted 36 days.

Samples

The purpose of my second experiment was to examine how individual Daphnia magna develop in water from each of the test sites. To begin this experiment I set up plastic cups in a grid system. There were four cups per each site number. Each of these cups was then filled with the corresponding type of water. Again, four cups were used for the control, using spring water. To each cup I added an age-controlled Daphnia magna. Every day I documented their heart rate and eye reflex. In addition, I also documented the number of births. Every week I fed the Daphnia magna the liquid invertebrate food. I continued this experiment until all of the Daphnia magna had reached the end of their life cycles. During both of my experiments, my raw data was documented in a notebook and then transferred to a computer for analysis at the end of the experiments.

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