In order to determine if the carp have an impact on plant growth, we decided to grow duckweed in five mini-environments. Each environment consisted of a 500mL beaker filled with 300mL of water. To each beaker, five duckweed fronds were added, each with two lobes. To lower the amount of growth error (from occurrences such as illness, insects, etc), each environment was replicated three times. We set up a control group with de-ionized water and two other aquatic environments with relatively high and low phosphorus levels. This left us with the five mini-environments: water from within the enclosure, water from outside the enclosure, a high and a low phosphorus aquatic environment and a control group using de-ionized water.
In order to adequately distribute a high and low amount of fertilizer, to compare against the natural environment, we combined one teaspoon of liquid fertilizer to two liters of de-ionized water ("High Phosphorus" treatment). We then used a serial dilution by pouring 100mL of stock solution into a 1,000mL beaker filled with 900mL of de-ionized water. After pouring 10mL of this new solution into the 1,000mL beaker we added 990mL of de-ionized water to make the "Low Phosphorus" treatment. The 1,000mL were then divided up into the series of beakers listed above, leaving 100mL of water to be discarded. The high and low phosphorus groups were used as a measure, to give an approximate idea of the effect of phosphorus in synthetic fertilizer on plant growth.
Over a three-week period, the duckweed's growth was recorded by counting each individual frond, and grouping them according to the number of lobes. A plant, for instance, with three lobes was recorded separately from a plant with two lobes. Single fronds were also counted separately, as well as dead or dying fronds (noted as being white from lack of chlorophyll or chewed away by the occasional mite). The data were then entered into an Excel spreadsheet and graphed for further analysis.