How does a farmer's fertilizer cause a dead zone in the ocean?

Question

How does a farmer's fertilizer cause a dead zone in the ocean?

Question 3 options:

What is used on land has no interaction with what happens in the ocean.

The run off from the farm brings nitrogen to the ocean. This causes the algae population to grow quickly. When they die the decomposers break them down and use up all the oxygen in the water. If there is no oxygen, nothing can live.

The run off from the farm brings nitrogen to the ocean. This increases the population size of all organisms. The presence of so many organisms, like fish, in a single area causes sharks and other predators to come. When they consume all the organisms in the area, it becomes known as a dead zone.

Answer 1

The second option is the correct answer. The run off from the farm, containing nitrogen from the fertilizer, enters the ocean and causes the population of algae to increase rapidly. When these algae eventually die, decomposers break them down and use up the oxygen in the water during the decomposition process. This depletion of oxygen creates an environment where most marine organisms cannot survive, leading to a dead zone in the ocean.