Many scientists believe the dead zone in the Gulf of Mexico is triggered by the vast quantities of nitrates (mostly from fertilizers) that run off farms into the Mississippi River and wash into the Gulf.

  !   Click on the area of the dead zone below to see the sequence of events that can lead to the development of the dead zone in the Gulf of Mexico. Use the next and previous buttons to move through the sequence.

Some scientists believe that the dead zone blocks certain types of shrimp from reaching their spawning areas. There is concern that this will eventually lead to increasingly smaller shrimp catches and may ultimately result in the collapse of the Gulf fishing industry.