Hypoxia and Medicine

What did humans do to cause the Gulf of Mexico Dead Zone?

Right now I am looking at the Gulf of Mexico Dead Zone and was just wondering.. what did humans do to cause this?

Public Comments

1. Dead zones (the non-oil-disaster kind) are created by excess nutrients being added to an ecologic system, primarily from agricultural runoff that brings with it fertilizers and other nutrient sources. No, this probably sounds like a good thing, but it isn't. What happens is that the algae and plankton at the surface (the producers) bloom madly, because yes, there is a sudden and large food source. Then the free-swimming animals get into it, like fish that feed on the producers. The fish population booms. Sometimes even higher animals, like sea turtles and dolphins even bloom (but not very common, due to their longer gestation periods). Unfortunately, there is one resource in this system that is still fixed - oxygen. You used to have 100 units of oxygen and 100 units of animals breathing the oxygen. Now you have 200 or 500 or 1000 units of life breathing the oxygen, and just life sticking people in a room with no oxygen input, the oxygen eventually thins and disappeared. With no oxygen, nothing can survive. Creatures die off in huge amounts, and those that are able to move, move out of the area and into somewhere that there is still an oxygen supply. The "dead zone" is called hypoxic -- no/little oxygen. Lack of oxygen and other food also causes the bottom-dwellers to die, PLUS the fact that in shallower waters, blooms of algae can actually block out enough sunlight that bottom plants the rely on photosynthesis die - and thus anything that feeds on them, too. These dead zones can exist for months until the ecosystem balances itself again, with the right amount of life and oxygen levels back to normal. So what did humans do? We neglected to look at the end-result of being irresponsible with our wastewater.
2. massive pollution
3. The dead zone was caused by massive amounts of agricultural runoff that flowed into the Mississippi River and then into the Gulf of Mexico