Dead zone found in La. sound

NEW ORLEANS – Researchers mapped a 250-square mile area of low oxygen this summer in Chandeleur Sound and say the dead zone possibly sprouted after state officials opened a river diversion to keep oil from a damaged BP well from fouling marshes.

The report by the Lake Pontchartrain Basin Foundation, which monitors water quality, said the dead zone formed sometime between May and July in the weeks after a Mississippi River diversion at Caernarvon was opened to wash oil threatening the Louisiana coast out to sea. River water contains a lot of nutrients, which can lead to a dead zone.

Still, John Lopez, a coastal scientist with the Lake Pontchartrain Basin Foundation, said it was far from clear what caused the dead zone this year and that it could be a phenomenon that happens every year.

He said the low oxygen might have suffocated immobile shellfish and invertebrates in Chandeleur Sound.