Eutrophication and the Gulf of Mexico Dead Zone

What is Eutrophication?

The Prcocess of Eutrophication

Eutrophication is when an ecosystem has an overflow of nutrients that is ultimately harmful. In the case of dead zones, runoff from water carries the nutrients from the land into the water encouraging algae and plankton growth in the water. The new creatures use up all the oxygen in the water, leaving it inhabitable to other organisms.

In the Gulf of Mexico, at the mouth of the Mississippi, there is a huge amount of Nitrogen coming into the ocean which forms a hypoxic zone in the northern gulf. Most of the Nitrogen flowing into the gulf if from the agricultural processes taking place upstream.

Where is the Dead Zone?

The Dead Zone reaches from the Delta of the Mississippi to the upper Texas coast

As of 1999, when the zone reached new records, The Gulf of Mexico dead zone was about 20,000 square kilometers. The area increases in the spring during the floods and is the smallest during the fall when water levels in the river are low. (Dagg)(Dagg, 2003)

“The [dead] zone occurs between the inner and mid-continental shelf… beginning at the Mississippi River delta and extending westward to the upper Texas coast.” (Bruckner)(Montana State University)

Dead zones can be found in almost any body of water including lakes, seas, and oceans. One example of another dead zone nationally is in Lake Erie. Other marine dead zones are in the Chesapeake Bay, the Black Sea, the Baltic Sea and off the coast of Oregon.

What are the Effects of Eutrophication?

After Microscopic plants and animals are attracted to the hypoxic zones of water, their dead cells and fecal matter attract bacteria that consume the oxygen found in the water faster than it is being replenished. (Cunningham, 2001)

Crustaceans, worms, and fish cannot survive under these circumstances, and those which cannot swim away are stranded and eventually suffocate. Hypoxic zones block shrimp and other fish from migrating into the deep ocean. Other places where dead zones have appeared, commercial fishing industries have plummeted.(Simpson, 2001)

Eutrophication leads to an algae boom in the nutrient rich water

What can be done to shrink the dead zone?

Simple options for reducing the nutrient level are limiting the nutrients, organic matter and chemical runoff from farmland, septic systems, sewage treatment facilities and manufacturing facilities. (Bruckner)(Montana State University)

One drastic option engineers are planning is to move the mouth of the Mississippi River. This seemingly radical measure is actually well overdue according to trends in the river. It would help the dead zone, by reversing the state’s marsh loss. The marshes would sift out and benefit from all the nutrient-rich sediment that causes the hypoxia; moving the Mississippi could also be more cost effective in case of rising sea levels. (Dean)(Dean, 2006)

A change in the way humans eat, less meat requires less agriculture necessary in the Mississippi River Basin. An alternative to this plan is to feed livestock with perennial plants instead of annual plants such as soybeans and corn. Corn growth is responsible for approximately 73% of the nitrogen put into the crops in the Mississippi River Basin, and a reduction in the production of corn could greatly reduce the amount of excess nutrients being rushed down to the Gulf. (Donner , 2007)

What has been done already?

The Environmental Protection Agency formed the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force to consider options for response to the hypoxia in the northern Gulf of Mexico. Also, a Hypoxia work group with representatives from the Departments of Agriculture, Commerce, Defense, Health and Human Services, and Interior, the Environmental Protection Agency, the National Science Foundation, and the Smithsonian Institution is compiling the knowledge, extent, causes and effects of the zone. The Hypoxia Work Group will also be examining the costs and benefits of reducing nutrient loads into the water through different methods. They are currently preparing a report to present to Congress during the next session. (National Centers of Coastal Ocean Science)(National Center for Coastal Ocean Science)

Since 1985, the Dead Zone has been growing