The condition when the amount of dissolved oxygen in a water body is alarmingly decreased is called:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. hypoxia.
The condition when the amount of dissolved oxygen in a water body drops to dangerously low levels is known as hypoxia. This occurs when oxygen levels fall below what is necessary to sustain most aquatic life, typically due to excessive nutrient pollution from sources like agricultural runoff, sewage, or industrial waste. These nutrients promote rapid growth of algae (algal blooms), which, when decomposed by bacteria, consume large amounts of oxygen. Hypoxia can lead to the death of fish and other aquatic organisms, creating 'dead zones' where life cannot survive. It is a serious environmental issue affecting freshwater and marine ecosystems worldwide.