Imagine an area the size of Hinds County with virtually no life: you can't drink the water; seeds rot in the soil; and only cockroaches can breathe the air. It's as if a nuclear reactor exploded and nothing survived.

Now imagine a dead area roughly 10 times the size of Hinds County. The 8,000-square-mile area would include all of Hinds, Madison, Rankin, Yazoo, Holmes, Attala, Leake, Scott, Smith, Simpson and Copiah counties, or just under 20 percent of the state's entire area.

Now you have a sense of how big the dead zone in the Gulf of Mexico is expected to be this year.

The Gulf dead zone is an oxygen-starved region that forms every spring and summer off the Louisiana and Texas coast, caused by excessive nitrogen and phosphorous in the waters of the Mississippi and Atchafalaya rivers. The nutrients are the result of farm fertilizers and animal wastes. In years where the waters are high with lots of spring rain, the dead zone expands. Scientists expect this year's zone to be between 7,450 and 8,456 square miles. The largest dead zone on record was 8,484 square miles in 2002, according to Science Daily, and the five largest zones, ever, have occurred since 2001. This year's zone will easily come in second, if not first.

"The growth of these dead zones is an ecological time bomb," said aquatic ecologist Donald Scaviato to Science Daily. Scaviato is a professor at the University of Michigan School of Natural Resources and Environment and director of the University's Graham Environmental Sustainability Institute.

The dead zones decimate many types of ocean wildlife. When the nutrients in the river waters hit the salt water, they trigger explosive algae "blooms." Then, as the algae dies and sinks, its decomposition near the ocean floor consumes the oxygen in the water, creating a dead zone. Bottom dwelling fish, shrimp and crabs can't survive in the oxygen-depleted water; they must move on or die.

"Without determined local, regional and national efforts to control them, we are putting major fisheries at risk," Scavia said.

The Gulf fishing industry has an annual value of more than $650 million, with shrimp its most valuable part. Scientists have linked dead zone hypoxic conditions with up to 25 percent declines in shrimp habitat on the Louisiana coast. The Gulf dead zone was one of 405 such zones seen worldwide last year, a 40 percent increase since the 1980s.