Near-record 'dead zone' predicted in Gulf of Mexico

James Marshall
June 11, 2019

ANN ARBOR-University of MI scientists and their colleagues are forecasting that this summer's Gulf of Mexico hypoxic zone or "dead zone"-an area of low to no oxygen that can kill fish and other marine life-will be approximately 7,829 square miles, or roughly the size of MA".

The National Oceanic and Atmospheric Administration is forecasting an area of about 7,800 square miles, roughly the size of MA or Slovenia. Once the excess nutrients reach the Gulf, they stimulate an overgrowth of algae, which eventually die, then sink and decompose in the water.

Rabalais has been measuring the hypoxic zone since 1985.

The US National Oceanic and Atmospheric Administration released its forecast for the year's hypoxic zone on Monday.

Widespread downpours around the Mississippi River Basin have led to record amounts of water, carrying large amounts of fertilizer and other nutrients downriver.

A task force of federal, tribal and state agencies from 12 of the 31 states that make up the Mississippi River watershed set a goal almost two decades ago of reducing the dead zone from an average of about 5,800 square miles (15,000 square kilometers) to an average of 1,900 (4,900).

The discharge in the MS and Atchafalaya rivers was about 67 percent above the average, officials said. The scientists warn of impacts to resources living there, including fish, shrimp and crabs.

USGS estimates that larger-than-average river discharge carried 156,000 metric tons of nitrate and 25,300 metric tons of phosphorus into the Gulf of Mexico in May 2019 alone. Those are about 18 percent and 49 percent above the long-term average, respectively.

NOAA drew a direct line between the dead zone and the price of shrimp in 2017.

NOAA's forecast assumes normal weather conditions, but large storms could impact the ultimate area of the dead zone.

A rush of spring rain feeding into the MS is what's expected to push 2019's zone to a near-record size.

The NOAA also stressed that nutrient levels distributed into the Gulf of Mexico vary from year to year due to the natural swings in precipitation and river discharge. "No reductions in the nitrate loading from the Mississippi River to the Gulf of Mexico have occurred in the last few decades".

University of MI scientists are predicting that the Gulf of Mexico will have a very large "dead zone" in 2019.

The agency said it operates 3,000 real-time stream gauges, 50 real-time nitrate sensors, and 35 long-term monitoring sites along the MS watershed.

It will be measured during an annual July cruise by Nancy Rabalais of the Louisiana Universities Marine Consortium.

Other reports by Click Lancashire

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