Bilogical magnification

Biological Magnification Cycle

Transcript of Bilogical magnification

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Biological Magnification


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What is Biological Magnification? Biological Magnification, also known as

Biomagnification, is the increase of substances that occurs in food chains. 

  These substances are usually found in contaminated

environments. Substances, such as pesticides and mercury, are absorbed by organisms due to their environment or the food they consume. The substance then accumulates inside the cells. 

 When an organism higher in the food chain eats multiple organisms below, each of them containing some of the toxins, the toxins becomes more concentrated in the higher food chain. Since this continues throughout the food chain, organisms higher in the food chain are the ones who will obtain the most toxins.


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Bioaccumulation Biological Magnification is often related with

Bioaccumulation, which is the increase of the toxic substance in an organism’s body. 

  These two terms are different: 

o Accumulation pertains to harmful substances in a living organism's body and its effects. 

oMagnification deals with the substance being passed along the food chain.

Bioaccumulation will cause a number of problems within the body that contains it. 

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How Biomagnification affects animals A common example of Bio magnification and Bioaccumulation is

the use of DDT in the 1960's and 1970’s. DDT, or dichlorodiphenyltrichloroethane, was overly used by humans as a pesticide. It soon found its way into the environment. 

  DDT and other toxins eventually climbed up the food chain, and

affected the bald eagles, nearly driving them to extinction. The DDT was absorbed by organisms which the bald eagles hunted, such as fish and carrion. Each bald eagle would eat multiple numbers of these fish and carrion.

  The DDT would accumulate inside each of the eagles' bodies.

The DDT would sterilize the birds or cause them to make fragile eggs that would break easily. This caused the birds population to dwindle rapidly.

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Bald Eagle Population


Figure 1

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How DDT rises in a food chain

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Mercury Mercury is a natural substance, that is found in very

small quantities in the ocean. Human interference with the environment, causes higher levels of mercury in the ocean. 

  Algae, a producer, consistently absorbs the mercury

which is found in its environment. However, it excretes it slowly. Often, zoo plankton will consume the algae and the mercury along with it. 

  The plankton is then consumed by small fish, which is

in turn consumed by larger fishes. Eventually, the fishes end up on human dinner tables. Humans, who consume fishes high in mercury, will easily become ill from mercury poisoning.

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Biological Magnification of Mercury

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The Biological Magnification of DDT in a marine ecosystem.

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Toxins that Bio magnify

DDT and Mercury are not the only toxin that biomagnifies. Other examples include, but are not limited to:  

PCB'S (polychlorinated biphenyls): used in insulators, as a plasticizer, and fire retardant. It biomagnifies, impairs reproduction and is widespread in aquatic systems.

  Cyanide is used in leaching gold and in fishing. It is a dangerous

toxin and is known to have effects on coral reefs.  

Selenium is concentrated by farming desert soils. It is toxic and causes reproductive failures in organisms. 

  Heavy metals such as mercury, copper, nickel, zinc, and lead

affect the nervous system and they may affect reproduction. 

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More Biological Magnification

Figure 5

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Why We Should Care Ironically, bio magnification and bioaccumulation are

caused by humans but also have a profound impact on us. 

  It can lead to neurological effects such as mental

retardation in infants who contract it through their mothers.

  A weakened immune system is also the result of bio


Some cancers are also linked through ingesting these toxins.

It can also lead to organ failure in both animals and humans.

Since some animals have weaker immune systems then humans, they will die faster which can lead to extinction if it continues.

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Prevention of Bio magnification In an attempt to eradicate bio magnification, the U.S. and

several countries worldwide have placed a ban on the use of DDT.

  People are trying to prevent harmful substances such as oil

and human waste from being dumped in water. 

Landfills are also trying to get rid of these substances because they can seep into ground water.


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Special Thanks / Citations


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Special Thanks / Citations Continued



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