Equilibrium Lab Report

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Method and Equipment Ecosystem jar contents A 2 litre plastic jar with 589g of sand was used. It was filled with the following: 1439ml of creek water, 1.73g Elodea, 6.13g Vallisnera and 3.30g of Lemna. The jar was covered with netting. Probe testing Using an electric probe, accurate levels for pH, O2 availability and water conductivity can be measured. Chemical testing Two 5ml samples of ecosystem water was extracted into two test tubes, where chemical indicators for phosphorus and nitrogen were used. Both were shaken and after 90 seconds were compared to the appropriate colour on the indicator sheet. Bug abundance testing Count the amount of observable bugs suspended in the jar per 30 seconds. Repeat 3 times and take the average as the…show more content…
Through this idea, the ideal equilibrium should be one that is not static, but fluctuates within a narrow range. This is seen within the weekly reading taken for the abiotic and biotic factors of the aquatic ecosystem. The oxygen levels stabilised by the third week around 11mg/L. This suggests that at this level, the photosynthetic output of the primary producers matched the output of the secondary consumers . The only two thriving forces within the ecosystem was the Lemna and the Daphnia, so accountability for the stabilisation level is clear. The Lemna growth was limited to the jars surface whilst the Daphnia rely on the abundance of food to manage their asexual growth. From initial to final, oxygen increased by 2.58mg/L which shows how the Lemna appears to the organism with more influence over the ecosystem (How et al., 2012). Conductivity shows the amount of organic molecules suspended in the water and the results showed a large increase which reached an equilibrium of 289 μs/cm. The decomposition of the Elodea and the Vallisneria influences the amount of suspended dead organic matter in the water. As a result, a rise in salinity allowed a greater food source for the Daphnia but also allowed the bacteria and algae to

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