How plant food affects microorganisms in water samples from Oklahoma’s water bodies

Tyler Johnson, Mandy Lawson, Shelbi LaMascus, Caitlynn Land, Tyler Ryan


Phosphorus and nitrogen eutrophication of water sources can create many biological problems, most commonly algal bloom formation, and consequently, nutrient depletion and harm to entire ecosystems. Previous experiments have shown that phosphorus and nitrogen can improve growth rate, although they can also stunt growth at high concentrations. To investigate how these elements affect the growth of microorganisms, we added plant food to water obtained from the Lake Hefner golf course and Lake Hefner fishing dock and waited one hour before measuring cell density. Using a hemocytometer, we calculated cell density in samples with and without plant food added. Both of the samples at the high plant food concentration (3.88 g/L) had a lower cell density than the control after 1 hour. However, the golf course’s cell density was affected much less. The low concentration (2.00 g/L) was less consistent, with the golf course showing an increase and the dock showing a decrease. Our results were unexpected, as we predicted that the plant food would increase cell density. This is likely because our one hour trial times were not long enough to allow the algae to grow sufficiently. Future research could encompass how different fertilizers compare to one another and how addition of nitrogen and phosphorus affects biodiversity.

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