WASHINGTON, DC, July 20, 2007 (ENS) – A team of federal government and university scientists is predicting that the "dead zone" off the coast of Louisiana and Texas this summer could be the largest since shelf wide measurements began in 1985, and much larger than the average size since 1990.

A dead zone is an area of low oxygen or no oxygen which can kill all marine life in it.

The scientists from the National Oceanic and Atmospheric Administration, NOAA, Louisiana Universities Marine Consortium, and Louisiana State University, led by R. Eugene Turner of LSU, predict this summer's "dead zone" may be as large as 8,500 square miles, an area about the size of New Jersey.

Since 1990, the average annual hypoxia-affected area has been approximately 4,800 square miles. The "dead zone" measured 6,662 square miles in 2006.

Tropical storms and hurricanes are capable of disrupting the physical structure of the water column and aerating the bottom layer.

While NOAA has predicted an active hurricane season for 2007, if no strong storms appear, this year's dead zone could equal the largest recorded in 2002 and stretch into Texas' continental shelf waters.

The "dead zone" is an area in the Gulf of Mexico is caused by a seasonal change where algal growth, stimulated by input of nutrients such as nitrogen and phosphorus from the Mississippi and Atchafalaya rivers, settles and decays in the bottom waters.

The decaying algae consume oxygen faster than it can be replenished from the surface, leading to decreased levels of dissolved oxygen. This low oxygen area is of particular concern because of its potential to affect the valuable Gulf fishery.

The forecast is based on nitrate loads from the Mississippi and Atchafalaya rivers in May and incorporates the previous year's conditions.

"I am anticipating a historically large hypoxic zone this summer because the nitrate loading this May, a critical month influencing the size of the area, was very high," said Turner.

"The difference between 2007 and 2002 cannot be explained by increased river flow. The riverine flow in May 2007 was 77 percent of the May 2002 discharge, but it contained 35 percent more nitrogen," he said.

The relatively high nitrate loading may be due to more intensive farming of more land, including crops used for biofuels, unique weather patterns, or changing farming practices, the scientists said.

Research indicates that nearly tripling the nitrogen load into the Gulf over the past 50 years has resulted in the widening dead zone.

"This prediction is an example of the ecological forecasting capabilities of NOAA and its partners. We believe such forecasts will become important tools for coastal managers in the coming years," said David Whitall, a NOAA scientist involved in this project.