Q.11 Why does the increased level of nutrients in the water affect the survival of aquatic organisms?

An increase in the level of nutrients in water body leads to an excessive increase in the population of algae in the water body.

When these algae die, they serve as a food material for the decomposers and this process utilizes a lot of oxygen which consequently leads to a decrease in the level of dissolved oxygen in the water body.

Hence this increases the mortality rate of fishes, aquatic plants and animals due to the shortage of dissolved oxygen.