How Dissolved Oxygen Responds to an Organic Nutrient in the Presence of a Decomposer

Abstract

Eutrophication is the process in which inorganic substances, such as nitrogen or phosphorus, leads to an “algal bloom,” increasing the population of algae while at the same time the population of the decomposers that break down the algae (Hoefnagels, 2012). The increased number of bacteria and algae uses up the dissolved oxygen within the water at a higher rate leaving no remaining oxygen for the other living things in the ecosystem. The amount of phosphorus in a sample of water affects the environment to the point the environment is anoxic, making the water a less viable option for habitation for organisms that require oxygen in order to live. We approached this problem through the use of a sample of water that already contained inorganic nutrients in it and adding more phosphorus to see how the amount of phosphorus affects the decline in dissolved oxygen. We allowed the samples to sit over a period of three weeks, adding yeast in week two to act as a decomposer, and tested the dissolved oxygen levels throughout the period. This research helps support the idea that phosphorus decreases the amount of dissolved oxygen to levels that cannot support life of organisms that require oxygen to survive.