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Dead Zones: Empty of Life?

By: Stephenie M.

Would you believe it if someone told you that there is an area of ocean water with low oxygen levels the size of New Jersey? Well, it’s true. Human actions are disrupting the environment, and the outcome is an unbalanced ecosystem. Ecological imbalance impacts humans, who are dependent on the Earth's ecosystem and its services. Its resources are essential to humans' well-being now and in the future. Without equilibrium, organisms are in jeopardy, because they depend on living and non-living features of their environments for their basic needs. When there is a change in the population of a certain species, it can cause population fluctuations and problems in the food chain of that ecosystem.

Humans are, unfortunately, negatively impacting the phosphorus cycle. There are four steps in the phosphorus cycle, which are weathering, absorption, decomposition, and sedimentation. This cycle is known as a biogeochemical cycle that is necessary for life on earth. A biogeochemical cycle is a pathway where substances circulate between living organisms and the environment. Synthetic and animal waste fertilizers are disrupting this cycle. Fertilizers utilized by plants are washing into bodies of water due to phosphate leftovers in a plant's water supply, and water runoff. Excess phosphorus in water is over-nourishment and leads to a process called eutrophication.

Human actions are impacting the water supply because nutrients from fertilizers are washing up into the bodies of water, causing excessive plant growth, and interference with activities. Image by C. Ophardt

Eutrophication occurs when there is an excessive amount of nutrients in the water caused by harmful fertilizers washing up into lakes and rivers. The nutrients, such as phosphorus and nitrogen in fertilizers serve as food for algae, after some time, a thick layer of algae will form at the top of the water known as an algal bloom, which causes plants at the bottom of the lake or river to be unable to absorb sunlight. Without sunlight, plants cannot undergo photosynthesis, since its stored nutrients will run out sooner or later, causing algae and plants to fall to the bottom of the water and undergo decomposition, the process of organic substances to break down. Decomposition needs oxygen to function, resulting in substantially less oxygen for organisms, causing fish to suffocate and die, creating a dead zone.

There are many dead zones each year around the world that are failing to support marine life. Image by Jutta Scheibe

Believe it or not, the Gulf of Mexico is a dead zone that is similar in the size of Delaware and New Jersey. The Mississippi River's water flow is responsible for creating a dead zone in the Gulf of Mexico, demonstrating how dead zones can spread throughout coasts, which is becoming an increasingly concerning problem. According to the United States Geological Survey (USGS), the yearly "delivery of nitrate from the Mississippi River to the Gulf has nearly tripled since the late 1950s", displaying an increase in the number of nitrogen levels found in a dead zone. Also, the number of dead zones has increased throughout the years. Scientists found a trend "that the number of dead zones in the world tends to double every ten years", due to more agricultural practices occurring.

The red represents the Gulf Dead Zone, where there is a small amount of oxygen and little to no life in the area. Picture by NOAA

If fish or other marine life stumbles upon a dead zone, these oceanic species will, sadly, suffocate as a result of no oxygen. Aquatic life dying in dead zones has disrupted biodiversity, which is a significant component of ecosystems. Unfortunately, less biodiversity inflicts decreased ecosystem productivity. Organisms depend on each other for basic needs and if you take away one component of an ecosystem, it can undermine the system, depending on its importance. For instance, a coral reef provides shelter for aquatic life, and it is a breeding ground for thousands of fish. They occupy 0.1% of the ocean area and support 25% of marine life. If this integral component would be eliminated from a biological community, it would be devastating for thousands of fish who depend on coral reefs.

Genetic and ecosystem diversity must increase because it is dropping fast everywhere. Biodiversity helps humans maintain a healthy state since many species provide food and plants are necessary to create medicine. Most importantly, biodiversity makes the earth habitable. Without a rise in biodiversity, many natural resources are threatened in the future.

Not only do dead zones negatively affect ecosystems, but they also threaten the economic state of fisheries and the government. Dead zones have a menacing potential to devastate the Gulf of Mexico’s seafood, which makes up "more than 40% of the nation's seafood", according to the National Oceanic and Atmospheric Administration (NOAA). Such an enormous loss can result in a seafood shortage in America that will impact the price of seafood. NOAA has also found that shrimp in the Gulf of Mexico dead zones has an economic loss on "consumers, fishermen, and seafood markets," as dead zones "drive up the price of larger shrimp" compared to smaller shrimp. Experts estimate that it will cost 2.7 billion dollars to fix the problem in the Gulf of Mexico, and the money will have to come from farmers or taxpayers. You may be thinking to yourself, "2.7 Billion dollars is a lot of money", and it is! However, there are great benefits of fixing this problem, including a change in the price of fish and shrimp stocks, healthier ecosystems, and increased biodiversity.

Dead zones showcase how current human activities provoke ecological damage, and so humans must take responsibility to prevent further environmental destruction. Therefore, farmers should implement alternative farming methods to prevent nitrogen and phosphorus from entering bodies of water in order to avoid destroying an ecosystem. Cover Crops can be a solution to reduce nutrients washing up into bodies of water. Cover Crops are grasses and legumes that cover and protect the soil and keep the living roots in, and they have many benefits as a result of a non-harvesting method. Benefits include an increase in organic matter, a boost in soil health, improved water infiltration, reduction in soil erosion, and the reduction of phosphorus and nitrogen from agricultural runoff. Cover crops are an investment to help improve soil and can also help increase yields and revenue.

Cover crops long roots trap nutrients preventing nutrient runoff.

Illustration by Elayne Sears

Many farmers, who have had cover crops for 4-5 years found an increase in yields. According to the Natural Resources Conservation Service(NRCS), farmers who planted corn in a cover crop field had "a 3.1 percent increase in yield compared" to a farm with no cover crops. Cover crops are a great way to decrease the number of new dead zones each year and benefit farmer's yield and their farms in the long term. We can also help reduce dead zones by eating less meat because the consumption of meat fuels climate change and animal waste, which washes into bodies of water, resulting in eutrophication taking its course.

Humans are responsible for creating dead zones, which are constituting inhabitable environments for marine life, and are also impacting the ecosystem and humans. Future generations will need to depend on the earth's natural resources, but that will be difficult because biodiversity is dropping quickly, and it doesn't help that the population is increasing rapidly. Fisheries and the economy are facing an economic loss as a result of dead zones escalating in number and spreading throughout coats, causing aquatic life such as shrimp and fish to suffocate. A solution to eutrophication is planting cover crops that trap nutrients in the soil and stop the runoff of phosphorus and nitrogen. If humans don't find alternative ways to reduce nutrient runoff, we could experience a surge in the number of dead zones, a shortage of seafood, and future generations could be in trouble.

Discussion Questions:

  • Scientists estimate that all coral reefs will disappear in the next 20 years. What do you think can be done to save them?

  • What occurs when aquatic life comes across a dead zone, will any life survive?

  • Are animal waste fertilizers being used correctly in the winter?

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