Record breaking Gulf of Mexico ‘Dead Zone’ this summer

According to predictions made by a team of NOAA-supported scientists from the Louisiana Universities Marine Consortium, Louisiana State University, and the University of Michigan, the Gulf of Mexico “dead zone” is likely to become record big this summer. If there predictions are true, we will see a dead zone the size of New Jersey (7,450 to 8,456 square miles). Additional flooding of the Mississippi River since May can however increase these numbers even further.

What is the Gulf of Mexico ‘dead zone’?

The dead zone is an area off the coast of Louisiana and Texas in the Gulf of Mexico where the oxygen level seasonally drops so low that most life forms living in and close to the bottom dies.

Dead zones are the result of large amounts of nutrients reaching the water, e.g. through waterways polluted by sewage and agricultural runoff. The excess nutrients stimulate rapid and massive algae growth in the affected area, a so called algae bloom. When the algae die, they sink to the bottom where oxygen dependant bacteria begin to break them down. The decomposition process consumes vast amounts of oxygen and soon the bottom and near-bottom waters become so oxygen depleted that all sorts of oxygen breathing organisms begin to die. This so called hypoxic area (an area where the oxygen levels are low to non-existent) is not just a problem for wildlife; it can also damage the economy of nearby states since it destroys habitat necessary for commercial and recreational Gulf fisheries.

The largest dead zone on record appeared in 2002 and measured 8,484 square miles.

Mississippi and Atchafalaya Rivers too rich in nutrients

During April and May this year, the Mississippi and Atchafalaya Rivers experienced heavy water flows that were 11 percent above average.

“The high water volume flows coupled with nearly triple the nitrogen concentrations in these rivers over the past 50 years from human activities has led to a dramatic increase in the size of the dead zone,” said Gene Turner, Ph.D., a lead forecast modeler from Louisiana State University.

“As with weather forecasts, this forecast uses multiple models to predict the range of the expected size of the dead zone“, said Robert Magnien, Ph.D., director of NOAA’s Center for Sponsored Coastal Ocean Research. “The strong track record of these models reinforces our confidence in the link between excess nutrients from the Mississippi River and the dead zone.”