The dead zone that develops in the Gulf of Mexico forms because the large amounts of nitrogen from fertilizers and sewage carried by the Mississippi River
A) kill the algae, which are the main food of primary consumers.
B) cause bacterial populations to grow rapidly and create widespread disease among secondary consumers.
C) lead eventually to large bacterial populations that deplete deeper waters of oxygen.
D) are poisonous to bacteria, which are critically important decomposers.

Question

Quizplus · Accepted Answer

The excess amounts of nitrogen from fertilizers and sewage flowing into the Gulf of Mexico through the Mississippi River stimulates the growth of phytoplankton, which in turn die and fall to the bottom of the ocean. This leads to a high demand for oxygen in the deeper waters as bacteria decompose dead algae, which result in depletion of oxygen in the waters, creating a dead zone where aquatic life cannot survive.

The Dead Zone That Develops in the Gulf of Mexico