Understanding the 'Dead Zone' in the Gulf of Mexico

First things first--what even is a "dead zone"? It's the popular term for what scientists call "hypoxia"--or areas of low oxygen in large bodies of water. Some of these dead zones have occurred naturally throughout history, but something else is going on in the Gulf of Mexico. 

Even before scientists started studying the dead zone closely, other people had begun to suspect that something was up in the Gulf of Mexico. In the 1950s, shrimp trawlers began reporting areas off the coast that had unusually low numbers of live shrimp for catching. 

By the 1970s, scientists knew something was going on in the Gulf. The size of the dead zones reported by fishermen seemed, at least anecdotally, to be growing. By 1985, researchers were actively tracking the size and timing of the Gulf dead zone every year. 

Environmentally, the Gulf dead zone is troubling.  A lack of oxygen in the ocean can lead to less and less biodiversity, which can in turn lead to a collapse of delicate ecosystems. Organisms subjected to these low-oxygen conditions experience changes to their reproductive systems, which leads to fewer and smaller offspring. 

It's not just scientists that are alarmed by this growing dead zone, though. It can also spell economic disaster for the businesses and communities that rely on Gulf Coast fishing to sustain themselves. If fish are smaller and fewer in number, there's less money to be made from them. 

The dead zone in the Gulf is caused by a chain reaction of events, but that chain begins with humans. When farms around the Mississippi river or its tributaries get rain, the fertilizer in the soil can make it into the river itself. And once it's in the Mississippi, it's only a matter of time before it makes its way to the Gulf of Mexico. 

Once these fertilizer nutrients reach the Gulf, the algae living there are delighted to see them. These nutrients put algae growth into overdrive, until they achieve what's known as an algae bloom. However, when these algae begin to die, the dead zone begins to take shape. 

As the algae die off, microscopic bacteria begin the decomposition process. Their presence reduces the oxygen levels in the surrounding waters, sometimes to a point where its detrimental to other marine life. 

In 2019, scientists recorded the size of the Gulf Dead zone at just under 7000 square miles--6952, to be exact. That's just smaller than the state of New Jersey. 

Since scientists began measuring the size of dead zones in the Gulf, a few have been larger than 2019's, but not many. It is the 8th largest in recorded history. 

States in the Midwest and South experienced some severe flooding in the spring of 2019—which means that more nutrient-rich soil made its way to the Gulf. Normally, this would indicate a larger-than-normal dead zone, but another major weather event may have interfered. 

In July 2019, Hurricane Barry made its way through the Gulf of Mexico and onto the state of Louisiana. While the storm had devastating effects, scientists believe that it also was able to disturb the waters of the Gulf enough to reduce the spread of the dead zone. 

So what's to be done? Luckily, this is a problem that can be reversed. The most important step in the solution is preventing fewer fetilizer nutrients from reaching the Gulf at all. Changes to fertilizers or farming methods could have a significant impact. 

However, we can also mitigate dead zones even when these nutrients do reach the Gulf. Seaweed is known to absorb phosphorus and nitrogen--the two main drivers of the dead zone. Massive seaweed farms in China have proven to be effective at reducing the concentrated nutrients around coastal areas. 

Similarly, organisms like mussels and clams have also been shown to be effective at filtering out nitrogen in the surrounding water. 

While the Gulf dead zone may be the largest in the United States, it's not the only area with problems. The Chesapeake Bay also struggles with dead zones caused by industrialization. 

Additionally, the Baltic Sea in Europe has had to deal with issues of hypoxia as well. They've had recorded dead zones of up to 37000 square miles!

For many years, the Black Sea was home to the largest dead zone in the world.

However, the size of this dead zone shrunk significantly in the 90s after the collapse of the Soviet Union. As a result, fishing has once again become a viable economic option in this region. 

With a proper plan, there's no reason to think that the dead zone in the Gulf of Mexico couldn't be reduced. In fact, there's a goal to reduce its size to just 1900 square feet by 2035. Whether we can actually work together to pull that off remains to be sesen.