northeastern university seal
EXPLORE NORTHEASTERN
News

Gulf of Mexico “dead zone” predicted to approach record size

On June 10, 2019, the National Oceanic and Atmospheric Administration (NOAA) released their annual forecast for the dead zone located in the Gulf of Mexico. A hypoxic zone, more commonly referred to as a dead zone, is an area of low oxygen concentrations in the ocean, which lead to death of the marine life population. This year the Gulf is expected to experience a 7,829 square mile hypoxic zone, coming close to the record setting 8,776 square mile zone of 2017. Roughly the size of Massachusetts, this dead zone will have both ecologic and economic effects and will test the Gulf region’s resilience.

Algae bloom in the Gulf of Mexico (source Flickr/National Oceanic Service)
Algae bloom in the Gulf of Mexico (source Flickr/National Oceanic Service)

The Science of Dead Zones
Dead Zones in the Gulf of Mexico are caused by fertilizer and waste nutrients that runoff into the Mississippi River, eventually being deposited into the ocean. Nutrients such as nitrogen and phosphorous allow for an algae bloom that eventually sinks in the ocean and decomposes. The decomposition process depletes the available oxygen and diminishes the source for other marine life. High amounts of rainfall and runoff this past spring have led to this record dead zone prediction. NOAA reports that in the month of May, discharge was 67 percent greater than the average since 1980. The U.S. Geological Survey reports an 18 percent increase in nitrate loads carried into the Gulf in May, in addition to a 49 percent increase in phosphorus loads when compared to the long-term average. These events are thought to be a direct result of climate change. More intense rainfall and flooding events lead to more fertilizer runoff, while warmer waters are capable of carrying even less oxygen to begin with.

Effects
The ecological effects of a dead zone can be felt through the food chain. Some animals are capable of relocating, such as shrimp, crab, or fish. Shrimp tend to find oxygen in shallow waters closer to the shore. This, however, stunts their growth. Other species that live closer to the seafloor, such as crustaceans and worms, do not have the ability to leave and will eventually die. This disturbs the food supply for other organisms and has a lasting effect on the region.

Mississippi River delta (source NASA/Jesse Allen)
Mississippi River delta (source NASA/Jesse Allen)

The impact of a dead zone, however, is not just ecologic. This summer’s dead zone is predicted to be located in an area commonly used by fishing vessels. It poses a threat to jobs that depend on the area and could increase the cost of working there. A 2017 study from Duke’s Nicholas School of the Environment found that the dead zone in the Gulf causes a rise in large shrimp prices and fall in the prices of smaller options. This has economic implications for all aspects of the market, including consumers and fisherman. Hypoxic events have been found to slow the growth of organisms in the area, if not cause them to die. The Duke study found that the presence of the dead zone in the Gulf creates monthly changes in the market price of Gulf brown shrimp. In the summer months when the dead zone is occurring, larger shrimp are found to become increasingly more expensive than small ones, widening the difference in prices. The broad effect of this dead zone presents numerous resilience challenges to the area. Not only will depleted or stunted species need to adapt and recover in order to prevent long term ecological harm, but the fishing and seafood industries may also be distorted as markets react to shifting supply and demand.

Moving Forward
States are working to regulate and reduce the amount of nutrients running into the Gulf each year. Dr. Eugene Turner, a professor at Louisiana State University in the College of the Coast & Environment, believes better management practices could minimize the scope of the issue. In addition, he suggests maintaining soil health through crop rotation, decreased fertilizer use, and crop covers that keep soil in place. Don Parrish, a senior director at the American Farm Bureau Federation, states farmers have already begun adopting practices that reduce nutrient runoff. However, they come at a high cost and can be technically challenging to learn and adopt. Practices such as precision farming and artificial intelligence are being used, but cannot be widespread solutions.

The ecological and economic effects of dead zones are poised to become more evident, and more challenging to combat, in coming years. Climate change will bring more rainfall and further record breaking dead zones. Low cost solutions and economic incentives are needed to prevent permanent changes to the market and environment. However these incentives must be well informed of the social and economic implications of a changing system. If these challenges can be met with resilience-informed action, communities will be able to minimize the effects of ecological stresses like dead zones and bounce back more quickly if disruptions do occur.

Sources and Further Reading

NOAA forecasts very large ‘dead zone’ for Gulf of Mexico – NOAA

What is a dead zone? – National Ocean Service

The Gulf could see one of the largest dead zones in history this year – CNN

Gulf shrimp prices reveal hidden economic impact of dead zones – Duke Nicholas School of the Environment

Massive 8,000-mile ‘dead zone’ could be one of the gulf’s largest – National Geographic