Eutrophication



Eutrophication 2820
Photo by: Arvind Balaraman

Eutrophication (pronounced you-tro-fi-KAY-shun) is a natural process that occurs in an aging lake or pond as that body of water gradually builds up its concentration of plant nutrients. Cultural or artificial eutrophication occurs when human activity introduces increased amounts of these nutrients, which speed up plant growth and eventually choke the lake of all of its animal life.

In nature, eutrophication is a common phenomenon in freshwater ecosystems and is really a part of the normal aging process of many lakes and ponds. Some never experience it because of a lack of warmth and light, but many do. Over time, these bodies of freshwater change in terms of how productive or fertile they are. While this is different for each lake or pond, those that are naturally fed rich nutrients from a stream or river or some other natural source are described as "eutrophic," meaning they are nutrient-rich and therefore abundant in plant and animal life. Eutrophication is not necessarily harmful or bad, and the word itself is often translated from the Greek as meaning "well nourished" or "good food." However, eutrophication can be speeded up artificially, and then the lake and its inhabitants eventually suffer as the input of nutrients increases far beyond what the natural capacity of the lake should be.

Words to Know

Algae: Single-celled or multicellular plants or plantlike organisms that contain chlorophyll, thus making their own food by photosynthesis. Algae grow mainly in water.

Nitrate: A salt or ester of nitric acid, which is a transparent corrosive liquid composed of nitrogen, hydrogen, and oxygen.

Phosphate: A salt or ester of a phosphoric acid, which is any of three acids that are formed when the oxide of phosphorus reacts with water.

Too much of a good thing

Natural eutrophication is usually a fairly slow and gradual process, occurring over a period of many centuries. It occurs naturally when for some reason, production and consumption within the lake do not cancel each other out and the lake slowly becomes overfertilized. While not rare in nature, it does not happen frequently or quickly. However, artificial or human-caused eutrophication has become so common that the word eutrophication by itself has come to mean a very harmful increase and acceleration of nutrients. It is as if something receives too much fertilizer or has too much of what is a good thing.

Humans increase the rate of eutrophication

Human activities almost always result in the creation of waste, and many of these waste products often contain nitrates and phosphates. Nitrates are a compound of nitrogen, and most are produced by bacteria. Phosphates are phosphorous compounds. Both nitrates and phosphates are absorbed by plants and are needed for growth. However, the human use of detergents and chemical fertilizers has greatly increased the amount of nitrates and phosphates that are washed into our lakes and ponds. When this occurs in a sufficient quantity, they act like fertilizer for plants and algae and speed up their rate of growth.

Algae are a group of plantlike organisms that live in water and can make their own food through photosynthesis (using sunlight to make food from simple chemicals). When additional phosphates are added to a body of water, the plants begin to grow explosively and algae takes off or "blooms." In the process, the plants and algae consume greater amounts of oxygen in the water, robbing fish and other species of necessary oxygen.

All algae eventually die, and when they do, oxygen is required by bacteria in order for them to decompose or break down the dead algae. A cycle then begins in which more bacteria decompose more dead algae,

An eutrophic lake. (Reproduced by permission of The Gale Group.)
An eutrophic lake. (Reproduced by permission of
The Gale Group
.)

consuming even more oxygen in the process. The bacteria then release more phosphates back into the water, which feed more algae. As levels of oxygen in the body of water become lower, species such as fish and mollusks literally suffocate to death.

Eventually, the lake or pond begins to fill in and starts to be choked with plant growth. As the plants die and turn to sediment that sinks, the lake bottom starts to rise. The waters grow shallower and finally the body of water is filled completely and disappears. This also can happen to wetlands, which are already shallow. Eventually, there are shrubs growing where a body of water used to be.

In the 1960s and 1970s, Lake Erie was the most publicized example of eutrophication. Called a "dead lake," the smallest and shallowest of the five Great Lakes was swamped for decades with nutrients from heavily developed agricultural and urban lands. As a result, plant and algae growth choked out most other species living in the lake, and left the beaches unusable due to the smell of decaying algae that washed up on the shores. New pollution controls for sewage treatment plants and agricultural methods by the United States and Canada led to drastic reductions in the amount of nutrients entering the lake. Forty years later, while still not totally free of pollutants and nutrients, Lake Erie is again a biologically thriving lake.

[ See also Lake ]



Also read article about Eutrophication from Wikipedia

User Contributions:

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Sarah
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Oct 3, 2008 @ 9:21 pm
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Nammy
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Oct 7, 2008 @ 2:14 pm
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Aaniya
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robert kirkham
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Oct 13, 2008 @ 1:13 pm
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Todd
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shirin
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looter
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Lily
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Mar 10, 2009 @ 7:07 am
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pius
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Mar 15, 2009 @ 6:06 am
this is clear and comprehensible information on eutrophication as a consequence of loss of our valuable wetlands.bravo !
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confuzed no more
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Apr 22, 2009 @ 7:19 pm
oh my god thanks i was searching the internet for hours looking for a article i could understand because my 7th grade science teachers thinks were in collage. thanks a bunch :D
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shantha meena
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Aug 21, 2009 @ 8:08 am
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John
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Aug 21, 2009 @ 12:12 pm
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Jimmy
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Sep 14, 2009 @ 8:08 am
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Ahsan
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Oct 7, 2009 @ 9:09 am
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Feb 3, 2010 @ 4:16 pm
Excellent info, but where is this info coming from, a reference of sources would be great!
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Feb 9, 2010 @ 8:08 am
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Feb 17, 2010 @ 8:08 am
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Mar 28, 2010 @ 3:03 am
Thanks! Great help with my chemistry assignment on water pollution!
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Apr 11, 2010 @ 11:23 pm
It's simple and interesting.I would like to know more about the other articles published by the author.Thank U.
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Jul 10, 2010 @ 7:07 am
it such a great help for me and my classmates in understanding more about eutrophication
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Aug 20, 2010 @ 7:07 am
How does it(eutrophication) starts and what are the impact of it in animals living in water
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Nov 18, 2010 @ 2:14 pm
its really helpful and in easy wordings that can be understood easily
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Dec 5, 2010 @ 6:18 pm
exactly what i was looking for to teach my class. thankyou
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Dandoa
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Dec 7, 2010 @ 8:20 pm
This article helped A LOT for my chemistry project. Thanks :)
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Jan 8, 2011 @ 4:04 am
VERY NICE INFORMATION ABOUT THE WATER ELECTRIFICATION
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Jan 24, 2011 @ 10:10 am
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Rae
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Feb 17, 2011 @ 7:07 am
I basically agree with everyone else here. I am doing a sophomore project in college. One significant issue I have recognized is that eutrophication is happening world-wide. This is beyond alarming to me. This should also eencourage us all to be more susutainable and look to improve this scary situation.

What does this algae do to the ecosystem? Pollute drinking water, take away swimming as a recreational activity, and add more aquatic species to the endangered list?
32
Sanae
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Mar 10, 2011 @ 1:13 pm
Great article. Provided all the information I needed in a concise and simple fashion. Really helped me with my environmental science project.
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Mar 10, 2011 @ 2:14 pm
Dear Science Clarified,
My name is Erica Kelley and, I am I sixth grader at Riverfield Country Day School in Tulsa, Oklahoma. This year we are doing a big project on polluted bodies of water. I have Lake Peipus in Russia and in Estonia and, I recently found that it is struggling from eutrophication. So, I went researching eutrophication and I came across you guys. I was wondering if you could answer a few questions about eutrophication if you don’t mind. If you have any question you can contact me at tumblingsmidge@gmail.com
1. How long had eutrophication been going on for?
2. Have you heard about eutrophication in Lake Peipus?
3. Is eutrophication hard to see?
4. How long have we known about eutrophication?
5. Do animals die from eutrophication?

Thanks for your time,
Erica Kelley
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Apr 5, 2011 @ 4:16 pm
This is an excellent article. I gained a better understanding of eutrophication for my science report. Thanks for posting this and explaining it very thoroughly!
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May 19, 2011 @ 4:16 pm
I realy like this article.It helped me in my studies.
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alex
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Jul 14, 2011 @ 8:20 pm
Very interesting and to the point article. I have always been interested in eutrophication and the whole process. I live in an area with many lakes and I've noticed when I look on Google maps, you can see the outlines of many lakes and former lake beds from the air. Also you can see where there once was a very large body of water, and now is a group of smaller, shallower lakes. Thanks
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Aug 9, 2011 @ 1:13 pm
When eutrophication start it was introduced by human activity nd ther is no minimizing of ths phenomenon
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Oct 26, 2011 @ 10:22 pm
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Nov 6, 2011 @ 2:14 pm
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bryan
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Feb 3, 2012 @ 7:19 pm
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Mark
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Feb 21, 2012 @ 5:05 am
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david
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May 15, 2012 @ 4:04 am
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charlie
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Feb 18, 2013 @ 4:04 am
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Question. ---> Many attempts to reduce food security by increasing food production are controversial, discuss. (70)
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tshering
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Apr 16, 2013 @ 1:13 pm
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jess
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Aug 12, 2013 @ 2:14 pm
Thank you for this article. I have to write a paper about cultural eutrophication for my A.P. Bio class and this is a great help!
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Aug 4, 2014 @ 8:20 pm
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Kay
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Oct 13, 2014 @ 8:08 am
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Emliy
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Oct 13, 2014 @ 6:18 pm
this was a great article and helped me immensely to complete my project
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Brittany N. Reed
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Nov 25, 2014 @ 11:11 am
Can anybody describe the difference between natural eutrophication and man-made eutrophication for me cause I can not think how to describe the difference between these 2 eutrophication. So can you explain to me about the difference from this question
that I have just typed in please thank you I would appreciate it.
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Keighley Taylor
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Feb 3, 2015 @ 3:03 am
this is not very useful but if you added a bit more that I needed then maybe I would say that it was extermly useful rather than saying that's its not
54
simsonrajarathinam
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Feb 25, 2015 @ 4:04 am
In nature, eutrophication is a common phenomenon in freshwater ecosystems and is really a part of the normal aging process of many lakes and ponds
55
simsonrajarathinam
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Feb 25, 2015 @ 8:08 am
In nature, eutrophication is a common phenomenon in freshwater ecosystems and is really a part of the normal aging process of many lakes and ponds
56
Anna
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Mar 21, 2015 @ 7:19 pm
Very helpful information for my science essay. thanks to whoever wrote it!
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Lesley
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Jun 8, 2015 @ 8:20 pm
thank you so much,that's really helpful, my science essay finally found some strong sourse.
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Maria
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Feb 7, 2016 @ 6:18 pm
What are the consequences of artificial eutrophication?
59
Curtis
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Mar 3, 2016 @ 12:12 pm
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Bongani
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Sonic
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Mar 27, 2017 @ 6:18 pm
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Apr 27, 2017 @ 3:15 pm
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