In a village in Karnataka, people started cultivating crops all around a lake which was always filled with water. They added fertilizers to their field in order to enhance the yield. Soon they discovered that the water body was completely covered with green floating plants and fishes started dying in large numbers. Analyses the situation and give reasons for excessive growth of plants and death of fish in the lake.

This situation is known as Eutrophication which is defined as the the growth of green floating plants in water in excess amount. Moreover, due to addition of fertilizers, Algae are grown in water because they require nitrates in water to grow and nitrate was present in the fertilizers. The situation mentioned above is very serious as due to growing up of large green floating plants, most of the Oxygen is utilized by them and there is no Oxygen left for water bodies like fishes. Due to lack of Oxygen to them, the fishes are dying in large amount.