Question

In the given image the fish died due to:

• A. decrease in dissolved oxygen.
• B. low pressure of water.
• C. low water temperature.
• D. increase in dissolved oxygen.

Answer 1

The correct option is A decrease in dissolved oxygen.

Nitrogen and phosphorous rich contaminants in water is a source of nutrients for algae. This helps the algae to flourish and then die. Once they die, they serve as food for decomposers such as bacteria. A large quantity of oxygen gets used up in this process. Thus, this lowers the oxygen content of water, leading to the death of aquatic species.