NASA satellite image of sediments from Mississippi and Atchafalaya Rivers emptying into Gulf.
What is the Dead Zone?
Oxygen deprived (hypoxic) conditions in the Gulf of Mexico have been recorded since the 1970s. Each spring, nutrient rich waters from the Mississippi and Atchafalaya Rivers empty into the Gulf of Mexico.
This freshwater layer, less dense than salt water, floats on top of the salt water, separating the oxygen in the air from the oxygen-depleted water on the bottom of the Gulf. The resulting Dead Zone lasts from early spring to the hurricane season, when hurricanes and tropical storms whisk away the freshwater layer and churn up water from the bottom of the Gulf.
Is the Dead Zone Growing?
What was once an every-2-to-3-year event soon became an annual occurrence. Last year, the Dead Zone was the size of Massachusetts.
Source: Mississippi River/Gulf of Mexico Watershed Nutrient Task Force. 2008. Gulf Hypoxia Action Plan 2008 for Reducing, Mitigating, and Controlling Hypoxia in the Northern Gulf of Mexico and Improving Water Quality in the Mississippi River Basin. Washington, DC.This March, researchers found regions of low-oxygen around coastal
Gulf Dead Zone Likely to Set Record - US News and World Report
In May, the team of scientists, which includes researchers from Louisiana State University and the Louisiana Universities Marine Consortium, found that nitrogen loading in the Gulf was 37 percent higher this year than in May 2007. The level was the highest since researchers began taking measurements in 1970.What Causes the Dead Zone to Grow?
The massive floods of June in the Mississippi watershed will dump more nutrients into the Gulf than ever before.
Non-Source Point Pollution
- Farmers, spurred by demands for ethanol, have been planting corn and soybeans like crazy. The use of fertilizer has increased as more land is put into crop production. The runoff from farmland contains nitrogen and flows into the watershed.
- Aging sewerage treatment plants leak human nutrients into the water supply.
- Decaying infrastructure like levees and dams give way, allowing flood waters to wash away septic tanks, soil, hazardous waste, cars, cows and houses.
Flood waters loaded with nutrients are now on the way to the Gulf of Mexico. This nutrient-rich freshwater layer provides a perfect environment for an overgrowth of phytoplankton. Plankton consume oxygen as they live, then the planktonic remains and their waste products fall to the Gulf floor, where they are eaten by bacteria. As the bacteria feed, they consume more oxygen, creating oxygen-deprived conditions.
Hypoxic waters appear normal on the surface, but on the bottom, they are covered with dead and distressed animal, and in extreme cases, layers of stinking, sulfur- oxidizing bacteria, which cause the sediment in these areas to turn black. These hypoxic conditions cause food chain alterations, loss of biodiversity, and high aquatic species mortality (www.tulane.edu/~bfleury/envirobio/enviroweb/DeadZone.htm)Why Should We Care about the Dead Zone?
What does the Dead Zone mean to us? Below are just a few areas of impact that I can foresee, and I am no expert.
- The Gulf of Mexico provides about 40 percent of the nation's seafood. Already there are problems with the toxicity of shellfish and oysters in the Gulf. Expect problems with the shrimp.
- Fishing is a multi-million dollar industry in the Gulf of Mexico. If there are no fish, shrimp or shellfish, there will be massive economic impacts. From the small fisherman who feeds his family to the shrimping fleets that fill the harbors, life will change.
- Blooms of phytoplankton kill fish which will wash up on the beaches of the Gulf. Beaches will close, tourism dollars will leave the area, devastating local economies.
- Birds and other creatures higher on the food chain will die, either from eating toxic fish, oysters and shellfish or from starvation. Annual migrations of birds will become disasters. The birding tourism market will collapse.
- Increased health problems for those living in coastal areas. Imagine the smell of the algae blooms and the dead fish.
Unfortunately, we do not have an EASY button for this issue that we may "click to take action." This is the time for sustainable farming, wetlands restoration, innovative water treatment and a lot of elbow grease. Until recently, there were just a few organizations like the Sierra Club, the Gulf Restoration Network and Gulf Base to help us find the answers.
In June 2008, The Mississippi River/Gulf of Mexico Watershed Nutrient Task Force released the Gulf Hypoxia Action Plan 2008 for Reducing, Mitigating, and Controlling Hypoxia in the Northern Gulf of Mexico and Improving Water Quality in the Mississippi River Basin.
Eleven key actions in the 2008 Action Plan outline critical needs to complete and implement nitrogen and phosphorus reduction strategies, promote effective conservation practices and management practices, track progress, reduce existing scientific uncertainties, and promote effective communications to increase awareness of Gulf hypoxia.EPA Requests Grant Proposals to Reduce Hypoxic Zone in Gulf of Mexico | Newsroom | US EPA
The Environmental Protection Agency put out a request for proposals (RFP) to:
. . . use water quality trading programs to reduce nutrient loads, particularly from the Ohio River, the Upper Mississippi River, or the Lower Mississippi River.What Can We Do to Help?
Write or call your representatives, both state and federal, and let them know how important this issue is to you, a registered voter and a concerned citizen of the US.
For readers outside the USA, it is estimated that there are 200 dead zones in the oceans of the world. This is a global problem. For more information please see the NASA Ocean Color site.