Bi o m a g n i f i cati on AP Environmental Science

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

Biological Magnification The process whereby certain substances such as pesticides or heavy metals collect in the bodies of organisms in progressively higher concentrations as it moves up the food chain The process whereby certain substances such as pesticides or heavy metals collect in the bodies of organisms in progressively higher concentrations as it moves up the food chain This is OPPOSITE to how energy moves up the food chain! This is OPPOSITE to how energy moves up the food chain!

The Problem: Peregrine Falcons Extirpated from much of U.S. The Peregrine Falcon became an endangered species because of the overuse of pesticides such as DDT during the 1950s, 60s, and 70s. The Peregrine Falcon became an endangered species because of the overuse of pesticides such as DDT during the 1950s, 60s, and 70s.

Osprey and Bald Eagles were declining, as well.

Meanwhile, in Borneo: Roofs began to fall Roofs began to fall Gecko-eating cats began to die, Gecko-eating cats began to die, and thriving rats brought plague and typhus and thriving rats brought plague and typhus The World Health Organization began to parachute cats into Borneo, but what was causing these problems? The World Health Organization began to parachute cats into Borneo, but what was causing these problems?

Finding the cause:

It seemed to be a chain The Data suggested DDT The Data suggested DDT Measurements of DDT levels seemed to multiply as the compound moved up the food chain: Measurements of DDT levels seemed to multiply as 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 Example Let’s look at our food chain to see how bio-magnification works: Let’s look at our food chain to see how bio-magnification works:

Food Chain Let’s say, for example, that each piece of plant material has one microscopic drop of methyl mercury. Let’s say, for example, that each piece of plant material has one microscopic drop of methyl mercury. 1 ppm equals percent 1 ppm equals percent 1 ppm is equivalent to 1 milligram of something per liter of liquid 1 ppm is equivalent to 1 milligram of something per liter of liquid

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

Food Chain If one small fish needs 10 insects to live, then one fish would have _____ microscopic drops of methyl mercury. If one small fish needs 10 insects to live, then one fish would have _____ microscopic drops of methyl mercury. 250

Food Chain One big fish eats 5 small fish to live. So, one big fish would collect a total of _____ microscopic drops of methyl mercury in its body. One big fish eats 5 small fish to live. So, one big fish would collect a total of _____ microscopic drops of methyl mercury in its body. 1250

Food Chain What about you and me? Lets say we eat 1 big fish a day for 3 days. We would collect total of ______ drops of methyl mercury in our body over the 3 days. This is how bio-magnification works! What about you and me? Lets say we eat 1 big fish a day for 3 days. We would collect total of ______ drops of methyl mercury in our body over the 3 days. This is how bio-magnification works! 3750

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

Depending on their chemical composition, substances are either water or fat soluble Depending on their chemical composition, substances are either water or fat soluble Water soluble substances are easily excreted by the body in various ways (digestive process, sweating, feces, urine) – Ex: alcohol Water soluble substances are easily excreted by the body in various ways (digestive process, sweating, feces, urine) – Ex: alcohol Fat soluble substances are not easily excreted and tend to be stored in bodily Fat soluble substances are not easily excreted and tend to be stored in bodily How does bio-magnification work?

DDT, a synthetic molecule, cannot be broken down or excreted – Life doesn't have enzymes that "know" how. DDT, a synthetic molecule, cannot be broken down or excreted – Life doesn't have enzymes that "know" how. Thus, it concentrates as animals higher on the food chain eat more and more food. Thus, it concentrates as animals higher on the food chain eat more and more food.

Peregrine Falcon DDT interfered with reproduction DDT interfered with reproduction The built-up in the falcon's fat tissues resulting in less calcium in the eggshells The dichlorodiphenyltrichloroethane built-up in the falcon's fat tissues resulting in less calcium in the eggshells Thinning eggshells Thinning eggshells Reduction in the number of eggs that survived to hatching. Reduction in the number of eggs that survived to hatching. In several parts of the world, such as the eastern USA and Belgium, this species became extinct as a result. In several parts of the world, such as the eastern USA and Belgium, this species became extinct as a result.

Bald Eagle Bald Eagle was severely affected in the mid-20th century by a variety of factors Bald Eagle was severely affected in the mid-20th century by a variety of factors Thinning of egg shells attributed to the use of the pesticide DDT Thinning of egg shells attributed to the use of the pesticide DDT Female eagles laid eggs that were too brittle to withstand the weight of a adult. Female eagles laid eggs that were too brittle to withstand the weight of a adult.

What is the point?

Pesticide Resistance In the beginning, most pests were sensitive to DDT but a few were resistant The resistant forms survived and reproduced In the end, most pests were 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