A planned increase in US ethanol production from corn would spell environmental "disaster" for marine species in the Gulf of Mexico, said a co-author of a science study published Monday.

A boost in corn production will worsen the Gulf's so-called "dead zone," an area with so little oxygen that sealife suffocates, said Simon Donner, a geographer at the University of British Columbia in Western Canada.

"Most organisms are not able to survive without enough oxygen," Donner told AFP. "All the bottom-dwelling organisms that can't move away are probably going to die, while fish will migrate if they can."

Donner and Chris Kucharik of the University of Wisconsin used computer models to conclude that growing enough corn to meet US biofuel goals set for 2022 would cause a boost of 10 to 34 percent in nitrogen pollution in the Mississippi and Atchafalaya Rivers, which run into the Gulf of Mexico.

In turn, the study said, there will be more than a 95 percent probability of failure in American targets to reduce the Gulf dead zone.

The study is published Monday in the online Early Edition of the Proceedings of the National Journal of Sciences.

The Gulf's dead zone, first measured about three decades ago, has grown to cover an area as large as 20,000 square kilometers (12,400 square miles) each summer in the Gulf, which is ringed by the southern United States, Mexico and Cuba.

The zone is caused indirectly by nitrogen fertilizers used on cornfields in states like Illinois, Iowa, Nebraska and Wisconsin. Excess nitrogen runs into the Mississippi River, becomes nitrate, and feeds algae growth. When the algae eventually dies it sinks to the bottom and rots, a process that sucks oxygen out of the water and kills all other life forms.

Donner noted the continental United States already produces about half of the world's corn, in part for human consumption but mostly to feed livestock or make ethanol.

The authors predict the only way nitrate pollution could be controlled and ethanol targets met would be if American farmers stop raising meat animals on corn and dramatically change agricultural management techniques.

With oxygen levels in the Gulf's dead zone already as low as two parts per million or less, all commercial and sport fishing in the zone has been wiped out, said Donner.

But the fishery "doesn't have the economic value that corn production does," he noted. "You can think of it as an equity problem in a way. It's pollution from one part of the US damaging another part of the US."