Explain the process of eutrophication.

Eutrophication is the process by which a body of water is enriched with excess nutrients as a result of frequent runoffs from land; this result in excessive growth of some plants on the surface of the water.
When fertilizers are washed away from the land surfaces into the rivers as a result of water erosion, the fertilizers usually add nutrients to the water and bring about the growth of plants such as algae on the surface of the water. The plants that are growing on the surface of the water affect the organisms living in the water negatively because the plants will reduce the amount of light that get to the surface of the water.