By Julia Shanahan | July 12th, 2019
The 2019 Gulf of Mexico “dead zone” will be the second-largest recorded, scientists from Louisiana State University announced this week.
The “dead zone” – an oxygen-depleted area of water in the Gulf of Mexico caused by nitrogen and phosphorus – will cover 8,717 square-miles as of this summer. Unusually high river discharge from the Mississippi River in May contributed to the growth of the dead zone. Oxygen depletion, or hypoxia, also threatens marine life, including fish, shrimp, and crabs.
The National Oceanic and Atmospheric Administration also predicted the dead zone to reach record-highs. In 2017, the dead zone reached about 8,776 square-feet, as reported by the NOAA. LSU scientists predict the 2019 hypoxic area to be about the size of New Hampshire.
The NOAA also attributed the growth in the annual dead zone to the record rainfall and flooding that happened in the spring months. The U.S. Geological Survey estimated a total of 156,000 metric tons of nitrate and 25,300 metric tons of phosphorus were carried from the Mississippi River and into the Gulf of Mexico in May alone.
Iowa experienced record flooding from the Missouri River in the spring, which contributed to the nutrient runoff in the Mississippi River. Iowa remains a major contributor to the annual Gulf of Mexico dead zone.
Low oxygen levels appeared about 50 years ago when farming intensified in the Midwest, according to the press release from LSU. In the last few decades, there has not been a reduction in the amount of nitrogen and phosphorus from the Mississippi into the Gulf of Mexico.