Biological Magnification

Food chain or food web?

What is DDT?Chlorinated hydrocarbonConsidered highly toxic to insects, but didnt (immediately) kill mammals or humans.Popular because it killed mosquitoes (who spread malaria) and cockroaches (which are human pests).

Background InformationDDT was discovered in the 1930s by Paul Muller, a Swiss chemistIt was inexpensive, broad-spectrum, persistent chemical that was extremely toxic to insects but not to humans and other mammalsIt was used to control lice, mosquitoes, spruce budworm and beetles, and to help grow more economically productive crops.

In the 1950s Rachel Carson investigated the effects of DDT on wildlife. Her book, Silent Spring, chronicles a message that insecticides can have dangerous environmental effects.Rachel Carson has been credited with the creation of the Environmental Protection Agency (EPA).The EPA worked to ban DDT in the early 1970sDDT is still believed to be entering the Great Lakes ecosystem through rainfall and dust sources from halfway around the world, to this day.

The study of DDT provides a good example of biological magnification or biomagnification of the chemicals in the ecosystemBiomagnification is the accumulation of higher and higher concentrations of chemicals in individual organisms.It occurs when a chemical is ingested and cannot be broken down or excreted, leading to accumulation of chemical that they pass along a food chain.

Ecological PyramidParts per millionExplains how the accumulation increases because Secondary Consumers eat more than one Primary Consumer

http://www.youtube.com/watch?v=E5P-UoKLx1A I wasnt sure if you wanted the screenshot or to actually import the video, so I left it blank

Crushed egg shell next to normal egg shellDDT affected eggs are crushed when sat on by the mother bird

How does this affect us?

http://www.youtube.com/watch?v=LQ64sV0nSVU&feature=related

The PresentMany new pesticides are biologically based and breakdown readily upon contact with soil or in reaction to sunlightMuch more target-specific and less likely to damage on-target organisms.Persistence of a chemical is tested during the pesticide registration process by the Pest Management Regulatory Agency.Long term effects and overall impact of new and existing chemicals on ecosystems can only be partially evaluated by current laboratory testing procedures.

The Biomagnification GameGrasshoppersShrewsHawksTwo difference food sources (hence, two different colored Hersheys Kisses)