Question

A lake receiving domestic sewage shows

• A. Drying up due to algal bloom
• B. Increased fish production due to higher nutrient availability
• C. Death of fish due to oxygen depletion
• D. Increased food web organisation

Answer 1

The correct option is C Death of fish due to oxygen depletion

A lake receiving domestic sewage becomes eutrophic. Biological Oxygen Demand increases which indicate the presence of organic matter in the water body. High BOD indicates the great amount of organic matter. The dissolved oxygen in water is consumed by bacteria present in the organic matter of sewage or other discharges thereby depleting the oxygen of the water body. The decrease in oxygen can kill the aquatic life in the water body especially fishes that totally rely on the dissolved oxygen for their respiration.

Hence, the correct answer is 'Death of fish due to oxygen depletion'.