Every year copious amounts of fertilizer and nutrient-rich sentiment dump into the Gulf of Mexico from the mouth of the Mississippi River, feeding massive algae blooms so large that they starve the ocean of oxygen. These oxygen-depleted waters, which last year grew to the size of Massachusetts, form a vast "dead zone" completely devoid of all marine life.
Now a new study, published in the journal Environmental Science & Technology, says the problem stands to get far worse if the U.S. follows through on its current federally-mandated efforts to increase annual biofuel production to 36 billion gallons by 2022.
The federal mandate, which was passed by Congress in 2007 in an effort to reduce America's reliance on foreign oil, set targets for the U.S. to blend 36 billion gallons of biofuels a year into the U.S. fuel supply, up from the 11.1 billion gallons projected to be blended this year. That would increase biofuels' share of the liquid-fuel mix to roughly 16% from 5%, based on U.S. Energy Information Administration fuel-demand projections.
That may be good for releasing America's reliance on oil, but an increase in biofuel production that large would also mean more fertilizers washing off farm fields throughout the Mississippi River basin, which could be devastating to both the Gulf's marine ecosystems and its fishing and shrimping industry.
The most intense hypoxia levels (areas which are low in oxygen) are usually between 30 to 60 feet below the surface. Fish in this area can be "stressed", meaning they can die of suffocation or, at the very least, move to other areas, which adversely affects fishermen in the dead zone region.
The zone is already 17-21 percent larger than it was in 1985 when it was first measured, and the five largest Gulf dead zones on record have occurred since 2001, with the largest measuring at a sprawling 8,894 square miles. "The growth of these dead zones is an ecological time bomb," said ecologist Donald Scavia, a professor at the U. of Michigan School of Natural Resources and Environment.
The Mississippi is the largest river in the United States, draining 40 percent of the land area of the country. It also accounts for almost 90 percent of the freshwater runoff into the Gulf of Mexico. It's no wonder that any increase in biofuel production along the river's basin, which is America's farm belt, stands to have a profound impact on the size of the dead zone, which is already one of the two largest such zones in the world.
Government officials had hoped to reduce fertilizer runoff and shrink the zone to the size of Delaware by 2015, but that would be virtually impossible if biofuel production is increased as currently projected. Unfortunately it'll probably have to be one or the other.
The good news is that dead zones are reversible. One such example comes from the Black Sea dead zone, which was itself once the largest in the world. It mostly disappeared between 1991 and 2001, after fertilizers became too costly to use following the collapse of the Soviet Union. Fishing has again become a major economic activity in the region.
For more information:
- More on biofuels: See our biofuel explainer video hosted by Chuck Leavell.
- More on the dead zone: Check out our interactive graphic.
And watch this short documentary video about the impact of the dead zone on the Gulf's local fishing and shrimping industry: