Question

In village in karnataka people starred cultivating crops all around the lake which was always filled with water. They added fertiliser to their field in order to enhance the yield. Soon they discovered that the water body was completely covered with green floating plants and fishs started dying in large numbers. Anlyse the situation and give reason for excessive growth of plants and death of fishes in the lake.

Answer 1

Since people used excessive fertilizers in the fields, they were carried down to the lake during rains. As many fertilizers contain phosphates and nitrates, the water body became enriched with these chemicals. These chemicals promote excessive growth of aquatic plants and the surface of water was completely covered with plants. (Eutrophication)
Depletion of light in the water body and insufficient availabilty of dissolved oxygen and nutrients resulted in the death of fish.

Answer 2

$\large\bf\red{Solution☞}$

During rains fertilizers used for agriculture spreads to the lakes. Fertilisers contain phosphates and nitrates by which water body became enriched with these chemicals. These chemicals promote excessive growth of aquatic plants and the surface of the water was completely covered with plants. (eutrophication)

Depletion of light in the water body and insufficient availability of dissolved oxygen and nutrients resulted in the death of fish.