Issue

The hypoxic zone in the Gulf of

Mexico, the so-called dead zone

lacking enough oxygen to support

most marine life, is one of the largest

environmental issues of the decade.

Practical solutions, based on sound

science, are needed.

What

The hypoxic zone is in an area of

approximately 6,000-7,000 square miles

of water with oxygen levels below 2

parts per million. Trawlers are unable

to catch any shrimp or bottomdwelling fish at this low level of

oxygen, and dead organisms have been

found there.

Where

The zone occurs between the inner and

mid-continental shelf of the northern Gulf

of Mexico, from the Mississippi River

birdfoot delta westward, to the upper

Texas coast.

When

There has been awareness of the

problem since the 1970s, but scientists are

unsure whether or not this is a recent

problem that has been worsened by

nutrient application.

Why

The zone is caused by increased

nutrients from the Mississippi River,

especially nitrogen and phosphorus from

fertilizers, animal wastes, and domestic

sewage; seasonal river discharges worsen

the nutrient enrichment. Average nitratenitrogen concentration in the rivers

mainstem has doubled since 1950, with

commercial fertilizers being the largest

source. Nutrients encourage algal blooms,

alter the food chain, and eventually

deplete the area of oxygen.

Significance

The Gulfs hypoxic zone rivals the

largest hypoxic areas in the world such as

those in the Baltic Sea and Black Sea.

Change in distribution of shrimp and fish

pose a potential threat to the Gulf of

Mexicos $4 billion a year seafood

economy. Furthermore, though the Gulf

bears the effects of the nutrients, the

source of the nutrients is a national

problem, involving the entire interior

watersheds of the Mississippi River Basin

and especially States from the Upper

Mississippi ValleyMinnesota, Wisconsin, Iowa, Illinois, and Missouriand the

Restoring Life to the Dead Zone:

Addressing Gulf Hypoxia, a

National Problem

Interior watersheds of the Mississippi River Basin, the source of materials causing the 6,000- to 7,000-

square-mile dead zone, or hypoxia in the Gulf of Mexico.

Distribution of water hypoxia from July 21-25,

1998. Data from Hypoxia Monitoring Studies of

N.N. Rabalais, R.E. Turner, and W.J. Wiseman, Jr.

U.S. Department of the Interior

U.S. Geological Survey

USGS FS-016-00

June 2000

For more information, contact:

U.S. Geological Survey/National Wetlands Research Center,

700 Cajundome Blvd., Lafayette, LA 70506; 337-266-8500;

Fax: 337-266-8513; http://www.nwrc.usgs.gov
lower Mississippi ValleyTennessee,

Arkansas, Mississippi, and Louisiana.

Solution

The FY1999 Department of the Interior

budget for USGS contains a request for the

National Wetlands Research Center to

conduct a $200,000 pilot project to

demonstrate how to use wetlands to

reduce nutrients.

Attacking theProblem

Background

About 25% of the nitrogen load in the

Mississippi River originates in the Lower

Mississippi River Valley, downstream of

the Mississippi-Ohio River confluence.

While most work related to the hypoxia

issue involves either nitrogen reduction in

the upper reaches of the Mississippi Basin

or in understanding the relation of nutrient

loading and the hypoxia zone offshore, the

USGS National Wetlands Research Center

has chosen to take another approach

using inland and coastal wetlands to

attack the hypoxia problem.

Research Activities

With NAWQA researchers, Center

scientists will

 Assess the role of coastal and inland

wetlands in reducing nutrients that

are transported into coastal waters.

 Develop a model of interactions

between wetland and

other habitats and

water quality.

Users

Information from the

research is particularly

needed by the U.S. Fish

and Wildlife Service,

National Oceanic and

Atmospheric

Administrations National

Marine Fisheries Service,

National Park Service, U.S.

Environmental Protection

Agency, U.S. Department of Agricultures

Natural Resources Conservation Service,

and the States of Arkansas, Texas,

Louisiana, and Mississippi.

Future

With additional funding, the Center can

 Assess the impacts of nutrient

enrichment on wetland and estuarinedependent biological resources, in

cooperation with the States of

Mississippi, Texas, and Louisiana, the

National Marine Fisheries Service,

and the U.S. Fish and Wildlife

Service.

 Assess the effects of agricultural Best

Management Practices in reducing

nutrient inflows at the watershed

level in the Lower Mississippi River

Valley.