Mississippi flooding could mean largest Gulf dead zone ever

Each year when the nutrient-rich freshwater from the Mississippi and Atchafalaya rivers pours into the Gulf, it spawns massive algae blooms. In turn, the algae consume the oxygen in the Gulf, creating the low oxygen conditions. Fish, shrimp and many other species must escape the dead zone or face dying.

Federal and university scientists predict this year’s zone will be between 8,500 square miles and about 9,400 square miles. The actual size of the dead zone will be measured over the summer.

The largest recorded dead zone was found in 2002 when 8,400 square miles of the Gulf was found to lack sufficient oxygen for most marine life.

The forecasts of the size of the hypoxic zone are usually close to the mark, although hurricanes have chopped them up in the past.

Eugene Turner, an oceanographer at Louisiana State University, said the dead zone has continued to get larger since it was first noticed and measured in the 1970s. He said the dead zone is getting worse with time.

The biggest contributor is the amount of fertilizer — and the nitrates and phosphates in them — that wind up in the Mississippi River each spring and get flushed out to the Gulf.

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