Daphnia Lab Report

Introduction:

All living organisms require oxygen to grow. Daphnia magna and Lemna minor (also known as Duckweed in its most common form) are no exceptions to this rule. Fertilizer is used to help plants, like Lemna minor grow. Plants give off the oxygen that other organisms, such as Daphnia magna, need. However, over-oxygenated environments can cause excess in the plant life. For example, algal blooms can lead to a reduction in the amount of light that can make it through the water (Rice University, 2013). This causes plants to die off, which then results in oxygen depletion. Oxygen depletion means that there is little to no oxygen in the water. An environment becomes anoxic when it has zero amounts of oxygen (Darley et al., 2013). This results

It will be referred to as Daphnia for this section. Lemna minor is duckweed, a plant, and it will be referred to as such. We collected three small jars with clear lids for each part of the experiment. They all were filled with 130 milliliters of filtered Lake Herrick water, measured with a graduated cylinder. Each jar also included five Daphnia, which were suctioned out of their previous environment and carefully dropped in to the jars. The experimental jar was comprised of the Daphnia, five milliliters of fertilizer, 1.764 grams of duckweed, and filtered lake water. We measured the duckweed by setting the weight of the scale to include the container, and then removing as much of the excess water from the plant as possible and depositing it on the scale. The control jar included the Daphnia, 1.727 grams of duckweed, and filtered lake water. An additional jar was added to remove any confounding variables, such as the possibility of the fertilizer alone being the direct cause of the possible diminishment of the Daphnia population. This jar was comprised of Daphnia, filtered lake water, and five milliliters of fertilizer. We measured the oxygen content with a dissolved oxygen probe as well as the weight of the duckweed on a weekly basis to check for oxygen compared to plant growth. In addition, we observed the state of our Daphnia and counted each of them, checking for life as

The experimental group contained both fertilizer and Duckweed, and we saw a large increase in the amount of Duckweed before it began to decrease again. This is compared to the control group, which lacked fertilizer, and did not have as sharp an increase or decline as the experimental group. By week two, we still had four Daphnia magna in the control group, while the numbers dwindled from five to one in the experimental