The Harmful Effects of Toxin-Producing Algae

Although the increase in the rate of algal growth can clearly be seen, measured, and correlated to increases in the use of fertilizers (especially nitrogen-based fertilizers) in farming practices around the world, one might wonder how algal growth could have a negative effect. After all, algae are a naturally evolved and essential part of any fresh or salt water ecosystem. Algae convert the sun’s energy to sugars, and many fish and other organisms feed on algae to survive. The fish and other organisms then become prey to other animals, indirectly making algae an important source of energy for predators as well. One might even draw the conclusion that an increase in algae would induce an increase in the growth and populations of many other organisms as well.

However, the implications of rapid algal growth are much more complex that a simple increase in food. Algal blooms can create hypoxic conditions in marine ecosystems. This decrease in oxygen levels kills fish and other organisms that rely on higher concentrations of oxygen dissolved in the water. A potentially more devastating effect in higher algal populations is the increase in algae that produce harmful toxins. One such variety of algae comes from the genus Pseudo-nitzschia, which is one type of algae that blooms recurrently off the coast of California.

Pseudo-nitzschia produces the neurotoxin domoic acid. In humans, domoic acid induces vomiting, nausea, diarrhea, abdominal cramps, headache, dizziness, confusion, disorientation, loss of short-term memory, motor weakness, seizures, cardiac arrhythmias, coma, and can even cause death in high enough concentrations. Humans who suffer from domoic acid poisoning typically acquire the elevated levels of domoic acid from mussels and other shellfish that eat the Pseudo-nitzschia in their environment. Because of the tendency for short-term memory loss after eating the contaminated shellfish, domoic acid poisoning is also referred to as Amnesic Shellfish Poisoning (ASP). Because of the dangers of domoic acid and the recurring blooms of Pseudo-nitzschia off the coast of California, the Department of Health Services requires shellfish growers in areas with a history of blooms to screen their harvests and test phytoplanton for levels of the neurotoxin. If the concentrations become too high, monitoring increases and admonitions against eating—and even quarantines on—the sea life in the area are set in place. In the spring of 2007, California saw a dramatic increase in the concentrations of domoic acid off their coast.

While seriously affected, humans are not the only organisms affected by the neurotoxin. The fish and other organisms, such as shellfish, that eat Pseudo-nitzschia do not generally receive high enough concentrations of domoic acid to suffer observable negative consequences; however, the species that eat the fish and shellfish are frequently affected. Much like DDT becomes more likely to kill as it is consumed by higher-level predators, domoic acid accumulates in higher and higher concentrations as it moves up an ecosystem’s food web, affecting the topmost predators the most. For example, domoic acid affects the brains of birds—such as pelicans—that eat fish. As a result, the many of the birds start having seizures. When the seizures occur during flight, the birds can end up flying to unfamiliar areas, or simply falling out of the sky and even drowning. When sea lions eat fish containing domoic acid during pregnancy, the domoic acid tends to accumulate in the amniotic fluid. As a result, the fetuses’ brains develop differently and the offspring tend to have epileptic seizures and strange behavioral habits later in life.

While the algae are a naturally occurring organism in the aquatic environment, the high levels of fertilizers in the water have increase their populations, causing detrimental effects to the aquatic ecosystem and affecting all levels of the food web, including humans. If the growth is not curbed by decreasing the amount of fertilizer released into the ocean, the affects could even spread to future generations of both humans and aquatic species.

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References

http://www.cop.noaa.gov/stressors/extremeevents/hab/features/ca_pn_050807.html

http://www.sciencedaily.com/releases/2008/06/080609103232.htm

http://www.sciencedaily.com/releases/2007/04/070427084149.htm

http://www.freedrinkingwater.com/water_quality/quality2/j-11-08-algae-blooms-cause-severe-oxygen-depletion.htm

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A History of Algae and Fertilizers

Algae has had a long history, from when it was first evolving, then becoming an important part of the diet of fish and other aquatic organisms, to today.
The first photosynthetic life forms (from which algae would one day evolve) were cyanobacteria. In water conditions that provided little oxygen and high competition for accessible sources of usable energy, cyanobacteria were able to manufacture their own by using just the sun, water, and carbon dioxide—all of which was plentiful in their environment. Eventually, other bacteria evolved to the point that they could encapsulate a cyanobacterium and use it as an organelle. The energy-storing molecules that the cyanobacteria produced could be used by the larger cell, a relationship that would benefit both the host cell and its offspring. Over time, these specialized cells with energy producing organelles (known as chloroplasts) eventually evolved into algae.

Long after algae had begun its evolutionary path, humans began to endeavor into the agricultural world. At first, agricultural methods were crude and yields were minimal—at least by today’s standards. As time went on, practices were refined, and people learned better ways to gain more yield for lower costs in resources. Finally, in 1843, the commercial fertilizer industry was born with the development of a process to make superphosphate. In 1849, mixed fertilizers were starting to be sold commercially, and fertilizers became more readily available to the average American farmer. By the 1890s, the average fertilizer consumption per year was 1,845,900 tons. As fertilizers were refined and improved and more was learned about which nutrients were most important to which crops, the amount of fertilizer consumed by American farmers continued to increase.

Much like plants, algae tend to grow more with the addition of fertilizer, especially fertilizers with ammonium nitrate phosphates. While fertilizers may not have created much of a problem at the beginning of their use, the amount of fertilizer that was used increased steadily over the decades to feed both people and the economy. In addition, much of the world has adopted the use of fertilizers for their crops. Fertilizers tend to seep into the groundwater, which can lead into rivers and streams which lead to lakes and oceans. When the fertilizers reach the algae, they can cause rapid growth and even an algal bloom, potentially upsetting the ecosystems in which the algae had played an integral role in shaping and developing.

Evolutionary history of Algae
A History of American Agriculture

Increase in Algal Growth as a Result of Globalization

Globalization is the spread of culture, economy, and religion into one large network that spans the entire planet. This spread can not only affect the people involved in trade and the global economy as a whole, but also the environment that we live in. As more countries become mechanized and move to a more westernized way of life, we are seeing more effects on the environment. Countries are increasingly effecting changes in agriculture and how people raise and handle their crops. There is an increase in the movement of non-native—and often invasive—species due to people. Most of all, we are seeing more use of agrichemicals such as ammonium nitrate in farming, as well as a higher dependency on fossil fuels and non renewable energy sources.

The Blog that I will be writing will detail how globalization effects the environment, specifically using algae as an example. I chose algae to be the focus of my blog because it sits at the bottom of the food chain, and while it may be small and seemingly unimportant, it can have a large effect on the entire environmental processes that take place above it. Algae can be affected by many things from temperature, chemical, and other changes that take place in its environment. Algae can give us a good view of what is happening in an ecosystem. It can also help us to understand how the planet as a whole is being affected because it occupies a large portion of our oceans, lakes, and other waterways.

The increase in the use of fertilizers in different countries all over the world has had a significant impact on the growth of algae. As excess fertilizer is washed into streams, it is taken down rivers into lakes and oceans. The algae that grow these areas are then exposed to the fertilizers and other chemicals, which provide the algae a more hospitable environment in which to grow and multiply, sometimes even causing algal blooms and dead zones.

Algae is a highly important part of aquatic ecosystems, providing food for many herbivorous creatures; however, too much algae in an area can disrupt the balance of a food web, ultimately resulting in the decrease in population of many species of plants and animals and—in extreme cases—dead zones. This decrease can have a harsh impact on the lives of peoples who rely on the benefits of oceans and lakes to survive and make an income. For example, fishermen can often be impacted if algal growth causes the decrease in the populations that they fish. Although they may still be able to catch some fish if the area is not rendered into a dead zone, the added competition of a global market can make it more difficult to profit from a smaller number of fish.

Although the most obvious solution to the problem of algal growth is to decrease or cease the use of chemical fertilizers, the problem is not that simple. If chemical fertilizers are banned or limits are placed on their use, farmers will get lower yields. The banning of fertilizer would therefore merely shift the hardship from fishermen to farmers, rather than eliminating it.

Spreading Dead Zones