NOAA forecasts very large ‘dead zone' for Gulf of Mexico

James Marshall
Июня 13, 2019

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 unusually high Mississippi River discharge in May controls the size of this zone, which will likely be the second largest zone since systematic measurements began in 1985". 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 MA. Nitrogen and phosphorous enter the river through runoff of fertilizers, soil erosion, animal wastes and sewage.

"A major factor contributing to the large dead zone this year is the abnormally high amount of spring rainfall in many parts of the Mississippi River watershed", the agency said in its annual "dead zone" forecast.

The NOAA estimates its size increase will be down to large amounts of rainfall.

Decomposition when the microorganisms eventually die reduce oxygen near the seafloor to a level where most marine life perish.

Scientists warn that the "dead zone" wreaking havoc on marine life in the Gulf of Mexico will cover nearly 9,000 square miles this summer.

The predictions for the size of the dead zone are based on computer models that make calculations based on typical weather conditions for the summer months.

NOAA said the forecast for this summer is close to the largest on record, which was 8,776 square miles in 2017.

Storms before last year's mapping cruise reduced that hypoxic zone to about 2,720 square miles (7,040 square kilometers), about 40% the average size that had been predicted, and among the smallest recorded.

Flooding rains in the Midwest are partly to blame for the anticipated size of this year's dead zone, according to NOAA. The five-year average is 5,770 square miles.

Editor's Note: This story clarifies that NOAA's forecast is an area roughly the size of the land in MA and removes the incorrect reference to the size of Turkey.

This story was reported from Los Angeles.

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