Scientists say the "dead zone" in the Gulf of Mexico off the Louisiana coast is likely to be the largest since they began keeping records in 1985.

The annual survey from LSU and National Oceanic and Atmospheric Administration predicts this year's dead zone, where the oxygen levels are so low no life can exist, will cover 8,800 square miles.

They blame the increased use of nitrogen fertilizers as farmers along the Mississippi River plant more corn to produce ethanol for fuel.

Today's prediction will be field-tested when measurements are taken in the Gulf later this month.