How pH Alters the Performance of Algae and Decomposers in an Ecosystem

Kristin McCay, Morgan Kiser, Jonathan Lane Navarro, Tori Lauren O'connor, Jie Ren


We conducted this study in order to gain a better understanding of why dissolved oxygen levels vary among different water conditions that are caused by point-source pollution. Dissolved oxygen levels can be an indicator of the health of an ecosystem because algae produces oxygen during photosynthesis. This oxygen is needed for algae cellular respiration, as well as the other trophic levels’ cellular respiration. Since we know pH level is both affected by pollution and crucial to algae productivity, we altered this in our experimental groups. We then measured dissolved oxygen levels over time in order to monitor how the algae were doing in the presence of yeast, among different pH levels. We found the neutral group to be the only pH that allowed for an overall increase in dissolved oxygen levels. The acidic group proved to be the most detrimental to dissolved oxygen levels in this experiment. Our hypothesis was supported by the results because less neutral pH caused a decrease in dissolved oxygen levels. We ran an ANOVA test to verify our results were significant.

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