BiBioommaaggnniiffiicaticationon

AP Environmental ScienceAP Environmental Science

When we try to pick out anything by itself, When we try to pick out anything by itself, we find it hitched to everything else in the we find it hitched to everything else in the universe. universe. John Muir John Muir

Biological MagnificationBiological Magnification

• The process whereby The process whereby certain substances such certain substances such as pesticides or heavy as pesticides or heavy metals collect in the metals collect in the bodies of organisms in bodies of organisms in progressively higher progressively higher concentrations as it concentrations as it moves up the food moves up the food chainchain

• This is OPPOSITE to how This is OPPOSITE to how energy moves up the energy moves up the food chain!food chain!

The Problem: The Problem: Peregrine Falcons Extirpated Peregrine Falcons Extirpated from much of U.S.from much of U.S.

The Peregrine Falcon The Peregrine Falcon

became an endangered became an endangered species because of the species because of the overuse of pesticides overuse of pesticides such as DDT during the such as DDT during the 1950s, 60s, and 70s.1950s, 60s, and 70s.

http://www.iowaccess.org/main/news/newsimages/peregrine.jpg

Osprey andOsprey andBald Eagles Bald Eagles were declining,were declining,as well.as well.

Meanwhile, in Borneo:Meanwhile, in Borneo: Roofs began to fallRoofs began to fall Gecko-eating cats began Gecko-eating cats began

to die,to die, and thriving rats brought and thriving rats brought

plague and typhusplague and typhus

The World Health The World Health Organization began to Organization began to parachute cats into parachute cats into Borneo, but what was Borneo, but what was causing these problems?causing these problems?

Finding the cause:Finding the cause:

It seemed to be a chainIt seemed to be a chain

The Data suggested DDTThe Data suggested DDT Measurements of DDT levels seemed to multiply as Measurements of DDT levels seemed to multiply as

the compound moved up the food chain:the compound moved up the food chain: Water to zooplankton: 800x Water to zooplankton: 800x Zooplankton to fish #1 = 31x Zooplankton to fish #1 = 31x Fish #1 to fish #2 = 1.7x Fish #1 to fish #2 = 1.7x Fish #2 to gull = 4.8x Fish #2 to gull = 4.8x Overall = 202,368x Overall = 202,368x

Food Chain ExampleFood Chain Example

Let’s look at our food chain to see how Let’s look at our food chain to see how bio-magnification works:bio-magnification works:

Food ChainFood Chain

Let’s say, for example, that each piece of plant Let’s say, for example, that each piece of plant material has one microscopic drop of methyl material has one microscopic drop of methyl mercury. mercury.

1 ppm equals 0.0001 percent 1 ppm equals 0.0001 percent 1 ppm is equivalent to 1 1 ppm is equivalent to 1

milligram of something per liter milligram of something per liter of liquid of liquid

Food ChainFood Chain

One insect eats 25 pieces of plant material, One insect eats 25 pieces of plant material, that would mean that each insect would have that would mean that each insect would have _______ microscopic drops of methyl mercury _______ microscopic drops of methyl mercury in its body. in its body.

25

Food ChainFood Chain

If one small fish needs 10 insects to If one small fish needs 10 insects to live, then one fish would have _____ live, then one fish would have _____ microscopic drops of methyl microscopic drops of methyl mercury. mercury.

250

Food ChainFood Chain

One big fish eats 5 small fish to live. So, One big fish eats 5 small fish to live. So, one big fish would collect a total of _____ one big fish would collect a total of _____ microscopic drops of methyl mercury in its microscopic drops of methyl mercury in its body. body.

1250

Food ChainFood Chain What about you and me? Lets say we eat What about you and me? Lets say we eat

1 big fish a day for 3 days. We would 1 big fish a day for 3 days. We would collect total of ______ drops of methyl collect total of ______ drops of methyl mercury in our body over the 3 days. This mercury in our body over the 3 days. This is how bio-magnification works!is how bio-magnification works!

3750

Food ChainFood Chain

Now let’s say that methyl mercury makes Now let’s say that methyl mercury makes living things sick. The more methyl living things sick. The more methyl mercury in the living organism, the more mercury in the living organism, the more sick it would get. From our example sick it would get. From our example above, which organism will be most above, which organism will be most affected by the toxin methyl mercury?affected by the toxin methyl mercury?

Depending on their Depending on their chemical composition, chemical composition, substances are either substances are either water or fat solublewater or fat soluble

Water soluble substances Water soluble substances are easily excreted by the are easily excreted by the body in various ways body in various ways (digestive process, (digestive process, sweating, feces, urine) – sweating, feces, urine) – Ex: alcoholEx: alcohol

Fat soluble substances Fat soluble substances are not easily excreted are not easily excreted and tend to be stored in and tend to be stored in bodilybodily

How does bio-magnification work?How does bio-magnification work?

How does bio-magnification work?How does bio-magnification work?

DDT, a synthetic DDT, a synthetic molecule, cannot be molecule, cannot be broken down or broken down or excreted – Life excreted – Life doesn't have doesn't have enzymes that "know" enzymes that "know" how.how.

Thus, it concentrates Thus, it concentrates as animals higher on as animals higher on the food chain eat the food chain eat more and more food.more and more food.

Peregrine FalconPeregrine Falcon

DDT interfered with reproductionDDT interfered with reproduction The The dichlorodiphenyltrichloroethane built-up in built-up in

the falcon's fat tissues resulting in less calcium in the falcon's fat tissues resulting in less calcium in the eggshells the eggshells

Thinning eggshells Thinning eggshells Reduction in the number of eggs that survived to Reduction in the number of eggs that survived to

hatching. hatching. In several parts of the world, such as the eastern In several parts of the world, such as the eastern

USA and Belgium, this species became extinct as a USA and Belgium, this species became extinct as a result. result.

Bald EagleBald Eagle

Bald Eagle was severely affected in the Bald Eagle was severely affected in the mid-20th century by a variety of factorsmid-20th century by a variety of factors

Thinning of egg shells attributed to the use Thinning of egg shells attributed to the use of the pesticide DDTof the pesticide DDT

Female eagles laid eggs that were too Female eagles laid eggs that were too brittle to withstand the weight of a adult.brittle to withstand the weight of a adult.

What is the point?

Pesticide ResistancePesticide ResistanceIn the beginning, most In the beginning, most pests were sensitive to pests were sensitive to DDT but a few were DDT but a few were resistantresistant

The resistant forms The resistant forms survived and reproducedsurvived and reproduced

In the end, most pests In the end, most pests were resistant to DDTwere resistant to DDT

"This we know: The earth does not belong to man; man belongs to the earth. Whatever befalls the earth befalls the sons of the earth. Man did not weave the web of life; he is merely a strand in it. Whatever he does to the web he does to himself."

- Chief Seattle