As if the BP oil spill didn't cause enough damage to the coastal areas of the Gulf of Mexico, large amounts of nitrogen and other nutrients from midwest agricultural lands has washed down the Mississippi river and entered the Gulf.
The abundance of nutrients causes a dramatic increase in the plant life initially (e.g. algal bloom) but then creates what is known as a 'hypoxic zone' or 'dead zone' as all the oxygen dissolved in the water gets used up by the photosynthesizing plants. This has huge ramifications for the animal life in those areas, and could be costlier to the ecosystem and the Gulf fishing economy than the BP oil spill.
