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article imageGulf of Mexico's 'dead zone' to be biggest on record this year

By Karen Graham     Jun 22, 2017 in Environment
The oxygen-poor dead zone in the Gulf of Mexico is expected to be the third largest ever this year, doubling in size to cover an area of the northern Gulf roughly the size of the state of New Jersey.
The annual prediction, “2017 Forecast: Summer Hypoxic Zone Size, Northern Gulf of Mexico," is the work of Louisiana State oceanographers, R. Eugene Turner and Nancy Rabalais.
This year's prediction estimates the dead zone will cover more than 10,000 square miles (26,000 square kilometers) off the shores of Louisiana and Texas. However, even during a normal year, the Gulf's dead zone is the largest in North America and second-largest in the world. The size and extent of the zone usually peaks in mid-July every year.
Dead zones can be found worldwide, and include the Baltic Sea, Black Sea, off the coast of Oregon, and in the Chesapeake Bay. Dead zones may also be found in lakes, such as Lake Erie.
What is the Gulf of Mexico's dead zone?
The Gulf of Mexico's dead zone is an expanse of hypoxic waters at the mouth of the Mississippi River. While the size of the zone can vary, it usually extends to cover an area about 5,000 to 6,000 square miles.
Map showing distribution of bottom-water dissolved oxygen from July 28 to August 3  2015  west of th...
Map showing distribution of bottom-water dissolved oxygen from July 28 to August 3, 2015, west of the Mississippi River delta. Black lined areas — areas in red to deep red — have very little dissolved oxygen.
The zone extends from the inner and mid-continental shelf in the northern Gulf of Mexico, beginning at the Mississippi River delta and extending westward to the upper Texas coast. A dead zone is characterized as having less than 2.0 parts per million (PPM) of dissolved oxygen, making it hypoxic.
The Gulf's dead zone is caused by the nitrogen-rich agricultural runoff in the Midwest farm belt. This fertilizer runoff, along with human and animal wastewater, fuels the growth of algae. When the algae die, it sinks to the bottom and decomposes, sucking the oxygen from the water and making it uninhabitable for fish and other marine organisms.
Wide range of effects resulting from dead zone
The biggest threat from a large and extended dead zone will be to the U.S. seafood industry. The Gulf supplies 72 percent of U.S. harvested shrimp, 66 percent of harvested oysters, and 16 percent of commercial fish. This means fishermen and coastal economies could suffer.
Shrimp boat in Biloxi channel with nets out shrimping while pelicans and sea gulls chase it down the...
Shrimp boat in Biloxi channel with nets out shrimping while pelicans and sea gulls chase it down the channel.
The Gulf Dead Zone may also slow shrimp growth, leading to fewer large shrimp,” the National Oceanic and Atmospheric Administration (NOAA), which funded the study, said in a statement. “This could mean higher costs of large shrimp at the marketplace and an economic ripple effect on the Gulf shrimp fisheries."
Easy solutions but few concerted efforts
From the federal government on down the line through state and local government bodies, information on mitigating the effects of fertilizers, septic tank waste and wastewater discharges into our river systems is readily available to everyone. The USGS estimates that in May this year, 165,000 tons of nitrate — roughly 2,800 train cars of fertilizer — plus 22,600 metric tons of phosphorus flowed down the Mississippi and Atchafalaya Rivers.
Fertlizing Corn
A farmer applying fertilizer to his corn crop
Lynn Betts
But here is how government works - In 2008, the New Orleans-based Gulf Restoration Network filed a petition asking the U.S. Environmental Protection Agency to issue standards for applying fertilizers in states along the Mississippi River.
The Environmental Protection Agency (EPA) responded, saying: that though it agrees “nutrient loadings to the Mississippi River and its tributaries are both harming upstream water quality and contributing significantly to hypoxia … in the Gulf of Mexico” it “does not believe that the comprehensive use of federal rule-making authority is the most effective or practical means of addressing these concerns at this time.”
So this is the way it stands today. Yes, some farmers are to be given credit for trying to reduce fertilizer runoff from their lands, but as long as large agribusiness farms continue in their usual way, nothing will change until it's too late to make changes.
More about Dead zone, Gulf of Mexico, hypoxia, Nitrogen, Phosphorus
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