Biological Magnification Bill Addo, Haram Chang, Jay Chen, and Nabila Akthar Biology SB1

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.

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. o Magnification deals with the substance being passed along the food chain. Bioaccumulation will cause a number of problems within the body that contains it.

How Biomagnification affects animals A common example of Biomagnification 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 sterelize the birds or cause them to make fragile eggs that would break easily. This caused the birds population to dwindle rapidly.

Bald Eagle Population Figure 1

How DDT rises in a food chain

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.

Biological Magnification of Mercury

The Biological Magnification of DDT in a marine ecosystem.

Toxins that Biomagnify 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.

Toxins in Bodies of Water ges/ddtwalleye-fig7.gif Figure 2

Toxins in Bodies of Water _fish.html Figure 3

Toxins in Bodies of Water _fish.html Figure 4

More Biological Magnification p/courses/env470/Lectures/lec39/Lec39.htm Figure 5

Why We Should Care Ironically, biomagnification 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 biomagnification. 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.

Prevention of Biomagnification In an attempt to eradicate biomagnification, 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.

Special Thanks / Citations Information

Special Thanks / Citations Continued Pictures ep.