Question

if too much fertilizer (nitrogen + phosphorus) washes into rivers, algae blooms occur. when the algae die, bacteria decompose them and use up all the oxygen in the pond. what is the result?
o carbon dioxide is stored in the sediments and used immediately by fish.
o nitrogen gas is permanently removed from the system supporting more life
o oxygen levels drop, harming aquatic life
o oxygen levels rise, supporting more fish

Explanation:

When algae die, bacteria decompose them and consume oxygen in the water. This leads to a decrease in oxygen levels which can be harmful to aquatic life.

Answer:

Oxygen levels drop, harming aquatic life