The Dead Zone

In the northern part of the Gulf of Mexico there is a yearly occurrence of what is now called the “Dead Zone” that has grown to nearly the size of Connecticut. This event is caused by algal blooms which causes a depletion of the oxygen in the water, this then results in a hypoxic zone. The lack of oxygen makes the water inhospitable for marine life and kills what is there if it is unable to move to other waters. Every year it appears that the Dead Zone is expanding and this has immediate effects on the surrounding environment and economy. The shrimp and oysters in Louisiana is typically a thriving source of income, but the Dead Zone is diminishing that. Just 30 years ago, 90% of shrimp consumed in the United States came from Louisiana, but now it is only 30%. 

The expansion of the Dead Zone can be credited to the expansion of fertilizer used in Corn Belt of the United States. In the past few decades, the usage of fertilizer in agriculture has increased significantly. A very important ingredient of fertilizer is nitrogen. Nitrogen is a limiting nutrient, meaning that it dictates the growth of many organisms. When put into fertilizer it typically generates much more of whatever crop is being grown than soil without nitrogen. These nitrogen-filled fertilizers have had a very positive impact on the agriculture industry, but the introduction of large amounts of nitrogen to very delicate ecosystems can have a very large effect. The Mississippi River Drainage Basin (pictured below) is what brings all of the runoff of fertilizers (containing high amounts of nitrogen) into the Gulf of Mexico.

Figure One: This map shows the Mississippi River Drainage Basin that connects all of the rivers in the Corn Belt and flows into the Gulf of Mexico.

The practices of intensive farming have had serious effects to environment. Just from 2002 to 2007, there was a 30% increase in the nitrogen levels of the water in the Mississippi River. Also, there has been a 300% increase in the level of algae-boosting nutrients in the past century. The increases of these factors negatively impact the creatures living in these waters.

Figure Two: This displays a large number of dead crabs washed ashore near the Gulf of Mexico’s Dead Zone.

In order to minimize this dangerous Dead Zone there must be a change in agricultural norms. The usage of nitrogen-filled fertilizers must be regulated in order to prevent more runoff and larger algal blooms. The protection of the Gulf of Mexico is vital not only for the environment, but also for the economies of those states surrounding it.

3 thoughts on “The Dead Zone

  1. Kristen, This is so interesting!! My blog post about Long Island’s nitrogen problem is so similar to yours. Though it’s cool we have a connection, this is also very worrisome. As I observed when researching New York, this occurrence can cause major devastation to an area. After reading your blog, I now fully realize that these problems are much larger than I could have imagined. It’s so interesting how I had never heard about these dead zone issues before, though they are so prevalent in the United States; it’s very alarming. Do you think that it a turnaround is possible? I see things such as algal blooms growing in China and can’t help but wonder: will this someday befall our own country?


  2. Kristen,
    This post was really interesting! It is truly incredible how much of an affect humans can have to the environment or an ecosystem. It is hard to believe that just by increasing nitrogen-filled fertilizers to improve crop growth, it could ultimately could create a dead zone and kill many marine organisms. I really like how you used data to represent what an impact humans have had, such as how adding nitrogen into the fertilizer has affected the nitrogen cycle and caused a 30% increase in nitrogen levels in the Mississippi river which caused a 300% increase in the level of nutrients that support algal blooms.
    Your post lead me to research how exactly algal blooms decrease the dissolved oxygen in a body of water and why dead zones occur. I found this really interesting website, you should check it out!

    Keep posting!


  3. Hey Kristen,
    I think that this is so fascinating! It’s crazy to think that there is a 300% increase in the amount of algae-boosting nutrients. Therefore, when you say that a large majority of the marine life is unable to survive in it makes sense since the algae takes up the oxygen. As you mentioned towards the end, I agree the main change has to happen within the agricultural industry, more specifically the fertilizer with nitrogen. Is this happening due to run off? Does this mean that just the areas around the body of water need to stop using the fertilizer? Overall, I think you did a fantastic job going in-depth about the issue at hand. Great job Kristen!


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