Nitrogen replaces oxygen in the water. The temperature of the water increases. Wave action carries away the dead algae. Bottom dwellers die and fish swim away.
I gave my students this multiple choice question: Nutrient-laden waters from heavy rains flow into the Gulf of Mexico. This produces an algae bloom in the ocean environment. As the algae decays, it uses up large amounts of oxygen along the coastline. Which would most likely happen to the area as a result?

Only one answer is correct among these 4 choices:
- Nitrogen replaces oxygen in the water.
- The temperature of the water increases.
- Wave action carries away the dead algae.
- Bottom dwellers die and fish swim away.

Could you tell me which one is correct?

Bottom dwellers die and fish swim away.