Deadly Bloom: Eutrophication at Work and Its Effects on Amount of Dissolved Oxygen

Tiffany Vang, Trevor Wilson


Sewage and fertilizers carry nitrogen and phosphorous into water sources by runoff and other methods. This is known as eutrophication (Hoefnagels, 2015). When pollutants are added to water, it can lead to an increase in algae and decomposers which will decrease the overall dissolved oxygen concentration in the water. We hypothesize that when there is an increase in pollution, the amount of dissolved oxygen in the water will decrease due to an increase in the population of the decomposers. We tested our hypothesis through experimenting with different concentrations of pollutions and yeast in water. We found that the sample with the yeast that acted as decomposers had a significantly lower concentration of dissolved oxygen than the ones that did not contain yeast. Our results show that in eutrophic waters, the abundance of decomposers leads to a decrease in dissolved oxygen, which could lead to the aquatic ecosystem to not be able to support other populations.

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