The Gulf Of Mexico's Dead Zone Is The Biggest Ever Seen
It has become a rite of summer. Every year, a "dead zone" appears in the Gulf of Mexico. It's an area where water doesn't have enough oxygen for fish to survive. And every year, the National Oceanic and Atmospheric Administration commissions scientists to venture out into the Gulf to measure it.
This week, NOAA announced that this year's dead zone is the biggest one ever measured. It covers 8,776 square miles — an area the size of New Jersey. And it's adding fuel to a debate over whether state and federal governments are doing enough to cut pollution that comes from farms.
The debate actually goes back many years, at least to 1985, when Don Scavia was a scientist at the NOAA. He and his colleagues asked some scientists, for the first time, to go look for a dead zone in the Gulf.
"We expected it to be there," Scavia recalls. They expected to find it because they knew that the Mississippi River delivers a heavy load of nutrient pollution, specifically nitrogen and phosphorus, into the Gulf.
Every year, the National Oceanic and Atmospheric Administration tasks scientists with measuring the dead zone in the Gulf of Mexico. This year's map, based on that data, shows a zone the collective size of New Jersey.
"Most of the nitrogen and phosphorus that drives this problem comes from the pper Midwest," Scavia says. "It's coming from agriculture."
Farmers use those nutrients on fields as fertilizer. Rain washes them into nearby streams and rivers. And when they reach the Gulf of Mexico, those nutrients unleash blooms of algae, which then die and decompose. That is what uses up the oxygen in a thick layer of water at the bottom of the Gulf, in a band that follows the coastline.
"Fish that can swim will move out of the way. Organisms that are living on the bottom, that the fish feed on, can't move, and they often die," says Scavia, who now is a professor of environment and sustainability at the University of Michigan.