Is it true that if the dissolved oxygen level drops to zero, the water will become septic. Give an example which could lower the dissolved oxygen content of an aquatic body.

Explanation

### Step-by-Step Solution:

1. **Understanding Dissolved Oxygen (DO)**:
- Dissolved oxygen is the amount of oxygen that is present in water, which is essential for the survival of aquatic organisms such as fish and other marine life.

2. **Impact of Low DO Levels**:
- When the dissolved oxygen level drops to zero, aquatic life cannot survive, leading to a condition known as septic water. Septic water is characterized by the presence of pathogens and a lack of oxygen, making it unfit for consumption and harmful to the ecosystem.

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