When the concentration of chemical nutrients typically compounds containing nitrogen or phosphorous in an ecosystem increases up to such an extent that it increases the primary productivity of the ecosystem then it is termed as Eutrophication.

Eutrophication is also a consequence of anthropogenic contamination with nutrients; particularly it happens due to the expulsion of fertilizers in the form of sewage waste matter into the ocean. Eutrophication provides excessive growth to the plants and decays them. It generally does not favor complicated plants but favors plankton and simple algae and also causes the harsh decrease in quality of the water.

In an aquatic environment, the excess growth of the plants like phytoplankton disrupts the ecosystem and its normal functioning. It also causes several problems, which include less oxygen supply, which is required by shellfish and fish to survive due to this water becomes cloudy, colored with some bits of yellow, green, red or brown. The resources of the oceans, rivers, lakes, hunting, fishing and other activities are also reduced by Eutrophication.