Photo courtesy of Nick Hewson via Flickr.

Why The Gulf Of Mexico Has A Massive “Dead Zone,” And How To Fix It

Photo courtesy of Nick Hewson via Flickr.

Planting a brand new flood forest could help fix the massive dead zone in the Gulf of Mexico.

Along the coastal stretch from the Mississippi river delta to Texas, a “dead zone” stretches for more than 5,000 miles.

During the summer season, no wildlife can exist here – simply because there is no oxygen

How does this happen?

Oxygen depletion is caused by drainage from the Mississippi river, which combines with the regular growth season to clog the stream with oxygen-depleting organisms. This is the process:

1. Massive amounts of nitrate from fertilizer, pesticides, and animal waste drains into the river from northern agricultural areas

2. Nitrates fuel the growth of algae

3. The algae is eaten by zooplankton, which multiply rapidly due to excessive nutrients

4. Zooplankton excrete a material that decays on the ocean floor and absorbs oxygen in the process.

When this process occurs on such an unnaturally large scale, the result is a seasonal dead zone that is – at the height of the annual algae bloom- devoid of oxygen.

It’s not just a problem in the Gulf of Mexico- at least 400 areas covering almost 95,000 square miles across the world are affected, according to the journal Science.

But in the Gulf alone, the economic impacts of such a dead zone is at least $82 million a year, from both lost fishing and tourism activity, according to Nature magazine.

The zone has also been slowly expanding for decades – but it doesn’t have to continue.

What can be done about dead zones?

Ocean dead zones like these are actually reversible.

After the collapse of the Soviet Union, farming declined after subsidies ended. As a result, the world’s largest dead zone in the Black Sea reversed to a natural state, as nitrate deposits from agriculture dropped substantially.

However, a similar situation in the U.S. would require the cooperation of farmers and authorities across large swaths of the country. The following map shows all the areas that would be affected:

Dead zones in the Gulf of Mexico is killing fishing and tourism.

Image courtesy of the Environmental Protection Agency via Wikipedia.

An EPA-coordinated initiative (pdf) is still studying the phenomenon, but it has yet to culminate in a large-scale effort.

A study from the University of Notre Dame, however, in partnership with the Nature Conservancy, found that planting or restoring floodplain forests – basically forests that grow in flooded areas – along river banks could significantly reduce the amount of nitrates that run downriver.

Every acre planted can absorb nearly 600 pounds annually.

Of course, this project would also require some scale. The Mississippi river releases nearly 1.7 million tons of nitrates per year.

If all nitrates were to be absorbed this way it would require 5.6 million acres of floodplains – more than the size of 4.2 million football fields.

Planting flood forests won’t be the only thing preventing dead zones, though. More likely, the cleanup of dead zones will happen through a variety of measures, including reduced agricultural and industrial waste, better drainage systems, and increased awareness among consumers and farmers.

Ole Skaar