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.

Nutrients and Coral Reefs

Figure 1:

Coral reefs are some of the most beautiful and one of the most complex ecosystems in the ocean. Coral reefs are made up of a wide variety of different organisms such as marine life, algae, and plant life. Due to all the biodiversity that is present in the reefs, the amount of nutrients that is present in the reefs is abundant. Coral reefs are so successful in containing biodiversity because they “tightly recycle nutrients, and all the plants and animals live in symbiosis.” However according to the article, some of the nutrients are limited in amount but also abundant in amount. So how can something that is so essential to life be limited but also be successful at the same time? I think coral reefs are so successful in being able to provide nutrients in order for it to strive because it has many different ways of gaining the nutrients it needs.

One way that coral reefs are able to gain carbon is through the symbiotic relationship between coral and the algae (zooxanthellae). The algae live inside the host coral, and garn its energy from the sun and are able to “fix carbon” through the process of photosynthesis. Thus, the algae provide energy for their host and in return gain nitrogen and phosphorus waste from its host. The nitrogen and phosphorus waste fertilize the algae, causing more algae to grow at a rapid pace. Meaning that more fixed carbon and more nitrogen and phosphorus waste. However, coral reefs significantly lack in the amount of fixed nitrogen. The algae to host relationship is symbiotic which allows those organisms not to lose fixed nitrogen but within the coral reef, fixed nitrogen is passed back and forth between plants and animals through the process of ingestion. Which means that if there is a lack of plants or a lack of animals many organisms would become deprived of fixed nitrogen which is essential in creating proteins and nucleic acid. Due to the lack of fixed nitrogen available, corals have to garn energy from a different source. Through the process of ingestion, corals ingest zooplankton or bacteria that come in contact with their mucus layer. Corals can also uptake fixed nitrogen when the water is low in ambient levels. These types of foods are not consistently available so the easiest form of fixed nitrogen that is available is in the form of ammonia. The ammonia becomes available to the corals because fish in the area are constantly excreting ammonia.

Another way that coral reefs gain nutrients is through a relationship called the mangrove-seagrass-coral reef. The mangroves which are located at the shoreline in which they provide many organisms with shelter and because of that they are very nutrient rich. At the mangroves a lot of denitrification takes place. The same happens with segrass. Although the process of denitrification occurs, seagrass provides shelter for many of the terrestrial animals that provide nutrients for the coral reefs. Due to the shelter they provide, fish are able to survive and provide coral reefs with solid nutrients rather than liquid nutrients through its feces.

Figure 2

With all this nutrients coming in, when is there to much nutrients and what are some of the side-affects. According to Olivieri, “With excess nutrients the zooxanthellae population grows uncontrolled and the balance of the nitrogen-carbon fluxes between the coral host and zooxanthellae is disrupted, resulting in a reduction of calcification and weakening of the coral calcareous skeleton.” (Olivieri, 1997).  In 1994, Hoegh-Guldberg conducted a study based on the population dynamics of symbiotic zooxanthellae in an area that was exposed to high levels of ammonia. He found that, “The calculated growth rates of zooxanthellae exposed to 20 µM or 50 µM NH4Cl were higher than those representative of zooxanthellae living in control corals.” (Hoegh-Guldberg, 1994). This supports his theory that the population of the zooxanthllae can become toxic when the amount of NH4CL in the sea water reaches 50 µM NH4Cl. If the amount of nutrients becomes too toxic for the ecosystem, all the nutrient cycles would be affected and many organisms that serve important roles in the cycles will begin to die out and eventually the coral reefs will begin to die themselves.

I think that coral reefs are successful in maintaining a nutrient efficient ecosystem because they are able to keep levels from becoming toxic even when there are loads of nutrients coming in from different sources. I think that we as humans also help keep them successful through the process of fishing.


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Fig. 2:

Hoegh-Guldberg, 1994

Olivier 1997

What’s happening with the Carbon Cycle

How the Carbon Cycle should be

The carbon cycle tells us how carbon, one of the most essential elements needed for life, travels from the surface of the earth to the atmosphere. A producer uses carbon dioxide in order to conduct photosynthesis. Then a primary consumer will eat the consumer and the carbon will also be transferred from the producer to the consumer.Then when another consumer eats that consumer or it dies the carbon dioxide will be released into the atmosphere and the cycle will restart. Carbon can also be stored for longer periods of time during the carbon cycle. Forests are a good carbon sink because trees can hold carbon for multiple years. Trees also provide the atmosphere with oxygen using carbon dioxide during photosynthesis. Recently, scientists have been observing that the majority of carbon sinks are located in the southern hemisphere but not in “big forests, but in dry places, even deserts, places where the only green things are shrubs or tall grass.” This had scientists wondering what was happening because this was not coherent with the carbon cycle, so they did research and learned that rain played apart in this occurrence. The year before this happened the precipitation in the southern hemisphere was more than usual and it caused the carbon dioxide to move to these dry environments. Scientists reported that “plants become more efficient with their water use under elevated CO2 in the atmosphere.” The plants in these areas then flourish with the rain and carbon dioxide because both water and CO2 are necessary for photosynthesis to occur. Ecologists were concerned about this change in the carbon cycle because they fear that it is not sustainable. Ecologist Daniel Metcalfe at the University of Lund in Sweden explained that having carbon stored in small plants is a short term solution because these plants usually live for a couple of years. He stressed that trees were the ideal place to store carbon for “tens or hundreds or sometimes even thousands of years.” The carbon cycle is one of the most important cycles that we must monitor because of its relevance to life on earth. With the recent increase in combustion of carbon due to human reliance on coal, oil, and natural gases the amount of carbon in the atmosphere is not healthy because the ratio of carbon in the atmosphere to carbon in the earth’s surface is supposed to be close. With the combustion of fossil fuels and the cutting down of trees in forests the ratio of carbon in the atmosphere to carbon on earth’s surface is becoming unstable. The carbon cycle is important to monitor in order to ensure the sustainability of life on our earth! Listen to the NPR on this it’s very interesting! Link is in the bibliography.


Long Island’s Nitrogen Downfall

The earth carries out it’s cycles day by day without us even realizing. It revolves around it’s axis each day, concurrently revolving around the sun each year. It rains, the sky clears, it rains again. The earth seems to do what it pleases, without any respect to the measly human being. But we as a race have more power than we realize. Our actions change this earth, not always for the better.

fig. 1 Montaulk is an example of a beautiful beach in Long Island

Long Island is a beautiful region of the United States, popular for it’s breath taking beaches and serene oceanside environment. For years, tourists have flocked the sandy seashore, and fishermen have angled the plentiful amounts of crustaceans and aquatic creatures living underneath the surf for profit. But the seeming perfection of this environment has been shattered. New data and observations have shown that the Nitrogen levels of well known areas such as Westhampton Beach, Huntington Bay, Shinnecock and Flanders Bay have skyrocketed, forcing the oxygen levels toxically low. This increase in nitrogen has caused many sea creatures to either leave or die off. These aquatic animals need oxygen to survive. As the number of creatures in the area lowers, unrestrained algae takes over, turning oceans and bays an unsightly and unhealthy green.

fig. 2 In areas of countries like China, this algae increase has become extreme.

But why does this occur? The answer can be found in a lesser known, yet integral cycle of the earth: the nitrogen cycle. Nitrogen is required for life of all plants and animals. Without it, we could not survive. Seventy-eight percent of the atmosphere is made of nitrogen, as well as three percent of our own human body. Nitrogen can be found in proteins and nucleic acids, in other words, in foods, and in DNA. As you can now see, nitrogen, though invisible, is essential. But nitrogen in large amounts can be detrimental to our environment. Large amounts of nitrogen, in the form of pollution, have entered the Long Island waters by way of soil leaching and runoff. Leaching occurs when fertilizer added to the ground does not bind with the soil, due to the nitrate in the substance being negatively charged. Runoff includes that from the sewer and septic pipes.

fig. 3 The nitrogen cycle is a complex process, but is necessary to sustain life on earth.

Other polluting contributors include an outdated waste water system, the use of pesticides, and emissions from power plants and vehicles. As these factors add up over time, nitrogen levels heighten, oxygen levels decrease, and the sea creatures dissipate. But the fish and animals aren’t the only things to disappear. The increase in nitrogen affects more than just the wildlife. It can negatively affect the economy, as it is doing now in New York. Tourists are slowly disappearing, disliking the polluted water, that is steadily becoming greener with algae. The pristine, once picture-perfect beaches may soon be a thing of the past. The fishing industry suffers as well, as their copious supplies run low, and what animals that remain will be sickly and oxygen-deprived. The main economic frame of the area is bending and shifting, all due to too much nitrogen.

fig. 4 Seen in this image is an example of runoff. This runoff is coming directly from the sewers and has many negative affects on the environment.

It seems like there is not much that can be done. Big factories and corporations will not soon change their polluting ways, and nor will ordinary humans, most living their lives oblivious to the the existence of the nitrogen cycle and its importance. Though I usually try to see the bright side in situations, the future does not look promising for Long Island, and possibly other beaches around the country, and world. I believe that pollution, though promoted extensively in a negative light, will not decrease anytime soon. Fertilizers and pesticides are an everyday tools for farmers; they will not risk the health of their crops and cease to use these things. The world takes their white sand and blue rolling surf for granted, but if people do not soon learn of the nitrogen cycle, all will soon turn green… with algae.

Stop Hogging the Nitrogen!

Like many other nutrients, nitrogen is crucial for life on earth; nitrogen is needed for the production of nucleic acids and amino acids, which make up proteins, which in turn builds the very physical beings of organisms. Producers depend on soil bacteria to fix nitrogen gas into the form of ammonium or nitrate in order to use it. But what if one species of a producer consumed all the available nitrogen in the soil like a vacuum cleaner cleaning up dust? That species would grow as if it had its own personal fertilizer. Needless to say, that particular species would flourish, and other plant populations, on the other hand, would dwindle.

Mahtaab Bagherzadeh, an undergraduate at Virginia Tech, participated in a study of how rhododendrons (more commonly known as azaleas) disrupt the nitrogen cycle with their greediness for nitrogen. In recent years, there has been a trend in areas losing various plant species when they are densely populated with rhododendrons. Declining plant species include chestnut and hemlock. Figure 1 is an example of dying hemlock leaves. Figure 2 is an example of a healthy bough of hemlock.

Figure 1

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Figure 2

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How does this nitrogen feud work? Well, microbes need nitrogen to sustain themselves as well. The relationship between microbes and plants is not one of commensalism; it’s not as if microbes exist for the sake of the life above ground. So they take whatever nitrogen they need and leave what’s left over for the plants. Rhododendrons release complex proteins that are difficult for microbes to break down. These proteins lock the nitrogen in organic compounds to create a hoard of nitrogen accessible to only rhododendrons. And without nitrogen, non-rhododendrons can’t survive.

Bagherzadeh and his advisor, Jeb Barrett, continue to study nitrogen and soil communities to address this issue with rhododendrons, but the take-away I am getting from this report is actually a reinforcement of the idea that these cycles and food-chains are more interactive with each other than a textbook would emphasize. Yes, nitrogen cycles through the atmosphere and the earth and so do carbon compounds. And yes, consumers eat producers before being decomposed into the ground by bacteria. But those cycles weave through one another, and if a species like the rhododendron disrupts a cycle, multiple issues pertaining to trophic interactions and nutrient cycles will ensue, not just ones respective to that one cycle.

Changing Biomes in South Africa and it’s Negative Effect

Could it be possible for a region to experience a change of it’s biome? If you think that this is absolutely ridiculous, I hate to break it to you, but you are wrong. It is completely possible for a region to have a change in it’s biomes overtime. But first, you may be wondering what a biome is, so here is a little refresher. A biome is a large area on the earth’s surface, which is defined by it’s abiotic factors such as climate, precipitation, geology, soil, and vegetation. In each of the biomes, the animals and plants have to learn to adapt to the environment. A common misconception is that a biome is an ecosystem, but that is actually not true. Although it may seem that a biome is a large ecosystem, in a biome the plants and animals have adaptive qualities and because of this you will also find multiple ecosystems in a biome. More specifically, the grassland biome is predominant with different species of grass, with a few trees and bushes scattered across. There are two types of grasslands, the Savanna Grassland and the the Temperate Grassland. The grassland biome can be considered the medium or the in-between of a desert biome and rainforest biome. Because of it’s temperatures, it can be considered to be either, and because of it’s lond dry season, it can be classified as a desert.

Now back to what I was saying, an example of changing biomes is currently happening in South Africa. Because of the increasing temperature, which has to do with climate change, and the change in precipitation, South Africa is facing the challenge of trying to preserve the grassland biome. The grassland biome is getting reduced in size, which is leading to an increase in the desert biome. You can see in figure one, that even though there are several different types of biomes in South Africa, there is a large difference in the size of the grassland biome from several years ago to now.

Figure 1.

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The reason that this is such a big deal is because if the grassland biome begins to decrease, it will affect all of the animals and plants that have adapted to the certain biome. Some of these animals may not be abel to make the transition, which will cause them to die. This in turn can have a drastic impact on the ecosystems in the biome and the food web. For instance, if a zebra is unable to find grass, which it’s main source of food, then the number of zebra’s will decrease. This will then effect the cheetahs, which feed on the zebras.

Another reason that this is harmful is because of the increase in aridity, which refers to the dryness of the atmosphere. Because of the aridity, the area of the atmosphere can shrink. If you look at figure 2, as of 2002, the area highlighted in blue was rather large, but as the years progress, the area has shrunk because there is double the amount of CO2 emissions.

Figure 2.

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All in all, the changing of biomes is extremely hazardous to the environment and the ecosystems in these environments. The excess levels of CO2 in the atmosphere area result of humans; therefore, with less CO2 emissions, the changing of biomes can hopefully come to an end.


Knowledge is Power!

Algal blooms and consequential dead zones are a problem plaguing the globe. In order to understand what algal blooms and dead zones are, and the impact they have on the environment, you have to understand the nitrogen and phosphorus cycles.

Algal blooms are caused because of human disruptions in the nitrogen or phosphorus cycle. Nitrogen and phosphorus are two of the main chemical elements of earth. The nitrogen and phosphorus cycles are biochemical cycles; biochemical cycles are simply cycles in which matter moves through out the earth.   An algal bloom is a rapid increase in the amount of algae in an aquatic environment. These blooms often occur because excess amounts of nitrogen and phosphorus enter the aquatic environment, and stimulate the increased growth of algae. (Science Daily)

Nitrogen and phosphorus are naturally occurring elements but they become overabundant from nutrient pollution. An example of nutrient pollution is runoff from farms using fertilizer containing a large amount of fixed nitrogen or phosphorus. Nitrogen fixation is the first step in the nitrogen cycle; it is the process by which nitrogen oxide from the atmosphere is converted into nitrate or ammonia. In the form of ammonia or nitrate nitrogen can be used in fertilizer to stimulate the growth of producers.  Phosphorus is more readily dissolved by soil than by water, so even a small amount of phosphorus within fertilizer runoff can stimulate growth of producers. Nitrogen and phosphorus may be helpful as fertilizers, but they can deadly when entering an aquatic environment. Nutrient pollution can occur in different ways, but the end result is always the sane, an abundant amount of nitrogen or phosphorus stimulating the growth of algae, creating an algal bloom. The abundance of algae in the aquatic environment turns the water green or red, (Figure 1 illustrates this). (National Geographic)

Figure 1


What is a dead zone and how does an algal bloom create it? Well, once the algae produced in the algae bloom dies, it sinks to the bottom, and bacterium decomposes the algae through cellular respiration. The bacteria takes in dissolved oxygen and produces carbon dioxide and chemical energy. The excess amount of decomposition decreases the amount of dissolved oxygen, creating hypoxic zones, areas with low amounts of oxygen. This lack of oxygen causes mass amounts of organisms requiring oxygen to die, or find new habitats, leaving an aquatic wasteland: also known as a dead zone.Now that you have an understanding of what algal blooms and dead zones are, and why they occur, it’s important to understand their significant impact on the environment. In 2007, an algal bloom in China’s Lake Taihu, the third largest lake in the country left 2 million people without water. “Overnight the city had no drinking water… what happened is folks woke up in the morning to make tea and found green Jello-like stuff coming out of the faucet. “ said Hans Pearl, a professor of the University of North Carolina-Chapel Hill. (Circle of Blue) Figure two shows an image of Lake Taihu:

Figure 2


Depriving an entire population of drinking water is a clear indication that something needs to be done in order to combat the nutrient pollution entering aquatic environments. Nonetheless, if you need something closer to home, in August, “a toxic bloom shut down the water supply system in Toledo Ohio. Since 2004 blooms of toxic algae shut down water supplies for more than 3 million people on three continents and have closed hundreds of inland lakes to recreation.” (Circle of Blue)

So, what should be done?

State legislation needs to be passed in order to allow government to regulate the amount of waste entering aquatic environments. But, because of the lack of political urgency in which this issue is viewed, nothing is being done. Teresa Fedor, a Democrat from Toledo articulates my view on the issue perfectly when she says, “We need regulations on seatbelts for cars to save lives, and on air pollution to shut down acid rain. So why would we not do this for the most fundamental, basic need of water?” ( Circle of Blue)

The only way to combat this issue is through limiting the use of fertilizers rich with nitrogen and phosphorus. Legislation passing laws limiting the use of such materials must enforce this. I think right now attention needs to be called to this issue; the people need to be informed of the environmental impact of algal blooms. If the people rally for it, politicians have no choice but to legislate. In this situation, knowledge is power!