While researching aquatic ecosystems, a student has compiled the following notes:
- Eutrophication occurs when a body of water becomes enriched with nutrients such as nitrogen and phosphorus.
- Excess nutrients spur the rapid growth of algae, creating algal blooms.
- When algal blooms die, the decomposition process consumes dissolved oxygen in the water.
- A severe reduction in dissolved oxygen, called hypoxia, can kill fish and other aquatic organisms.
- Major human contributors to eutrophication include agricultural runoff and untreated sewage.
The student wants to explain why algal blooms can result in fish die-offs. Which choice most effectively uses relevant information from the notes to accomplish this goal?