What is eutrophication?

Eutrophication is a result of nitrogen rich compounds leeching from farm land fertilizer/manure or other pollution methods to the river water ecosystem. The all of a sudden nitrogen rich environment in the river causes surface algi to grow at an increased rate and create a film over the water. This causes the deeper dwelling plants to die due to no light and then are acted on by decomposers aerobically lowering the water system's oxygen percentage. Aerobic animals such as fish therefore decrease in number due to lower oxygen and decrease in food source and or habitat in the deeper plants.