Coming To A Gulf Of Mexico Near You: A 'Dead Zone' The Size Of Massachusetts

Jun 11, 2019

An oxygen-sapping, fish-killing swath of algae is headed to Gulf of Mexico this summer.

Forecasters at the National Oceanic and Atmospheric Administration say the so-called dead zone is the result of agricultural activity, which courses through the Mississippi River Delta and spawns a massive bloom of algae that kills marine life. The buildup happens every summer, but researchers predict this year the dead zone could be as large as 8,766 square miles – roughly the size of the Commonwealth of Massachusetts. 

NOAA says higher than average amounts of rainfall along the river's watershed could make this year's dead zone especially aggressive.

An illustration of runoff from the Mississippi River Delta into the Gulf of Mexico. Nutrients from urban and agricultural runoff contribute to the so-called dead zones.
Credit NOAA

And, the agency warns, larger masses of algae could continually form each summer as heavy rainfall becomes the norm over much of the region and Texas, in particular. In an announcement of its forecast, NOAA's director of National Centers for Coastal Ocean Science, Steve Thur, said that was also a central finding in a multiagency climate assessment and that the rain could increase the dead zone, known in science speak as a "hypoxic zone."

"The assessment predicts an increase in the frequency of very heavy precipitation events in the Midwest, Great Plains, and Southeast regions, which would impact nutrient input to the northern Gulf of Mexico and the size of the hypoxic zone," Thur said.

The forecast, however, is just that: a forecast. Thur said it's possible the model, which also uses data from the U.S. Geological Survey, could overestimate the mass of the algae bloom in the Gulf, as it did last year. But, while the dead zone was smaller than anticipated last year, it was because the bloom was jilted by an overactive hurricane season.

NOAA expects this year's Atlantic Ocean hurricane season to follow a similar pattern.

NOAA has previously found these dead zones lead to stunted growth in Gulf shrimp. That ecological impact becomes an economic one for shrimpers, who haul in smaller shrimp, which net less money.