Introduction In an ecosystem the two most important factors are biotic and abiotic interactions. Biotic interaction is the interaction between living, breathing organisms such as fish, birds, and amphibian. Abiotic interaction is between non-living organism such as a tree absorbing sunlight and using the air to get the necessary nutrient to make its food. There is a balance between these two factors and when the balance is disrupted there are consequences. A substance that can cause that balance to be interrupted is pollution. "Pollution is not usually the result of deliberate mistreatment of the environment. The pollutants are almost always the by-products of otherwise worthy and essential activities “ producing crops, creating comforting homes, providing energy and transportation, and manufacturing products “ and of our basic biological functions  (Wright, R. T. (2008)). Although aquatic pollution is not intentional it is caused by runoff from producing crops due to human activities. And so when excess nutrient finds their way into bodies of water whether it be sea, rivers or lakes there is an increase in the algae population. Algae are photosynthetic organism that plays an important role in the aquatic ecosystem. When there is a bloom in the algae the balance between biotic and abiotic is unbalance and therefore causes problem for the body of water. This process is known as eutrophication. On the other hand, bacteria The interaction of fertilizer in the river water will ultimately result in higher bacterial populations. The introduced fertilizer will stimulate algae growth, thereby increasing nutrient supply for the bacteria allowing an increase in population growth. Methods We focused on the bacteria population and were given two jars filled with river water. This experiment was three weeks long and for each week we plated two samples of river water (control and experimental) on agar plates and observed.