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Environment

Gulf 'Dead Zone' Forecast Larger Than Average This Summer

mississippi_river_gulf_dead_zone_usgs_0.jpg
USGS
The Mississippi River near Vicksburg, Mississippi, looking northeast at the I-20 bridge in October 2016. The confluence of the Yazoo River is in the foreground.

Federal scientists are predicting that this summer’s “dead zone” in the Gulf of Mexico will be larger than average.

The dead zone is an area of little-to-no oxygen that forms every summer and is deadly to marine life. It’s primarily caused by excess nutrient pollution from human activities throughout the Mississippi River watershed.

Oceanographers with the National Oceanic and Atmospheric Administration recently released a report forecasting this summer’s dead zone to be approximately 6,700 square miles -- that’s higher than the average by 1,313 square miles. 

However,  it's still substantially less than the record of 8,776 square miles set in 2017. 

"Yes, 2017 was a significant year, largely because of the much higher than average May stream flows into the Gulf of Mexico from the Mississippi River watershed, ultimately resulting in the largest dead zone measured over the 33 years that we have been taking measurements," said David Scheurer, oceanographer with NOAA's National Ocean Service, in an email.

"This year, the discharges are much lower than in 2017."

Now, at the start of hurricane season, Scheurer said weather events can either enhance conditions or cause them to dissipate.

The annual prediction is based on the U.S. Geological Survey's river-flow and nutrient data. Researchers plan to take a survey cruise of the dead zone in early August to document the severity. 

“Not only does the dead zone hurt marine life, but it also harms commercial and recreational fisheries and the communities they support,” said Nicole LeBoeuf, acting director of NOAA’s National Ocean Service, in a press release.

“The annual dead zone makes large areas unavailable for species that depend on them for their survival and places continued strain on the region’s living resources and coastal economies.”