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Opening Questions

Opening Questions. Why is DDT harmful? What effect of DDT (DDE) is linked to the slow decline of birds of prey in the United States during the late 1960s and early 1970s?

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Opening Questions

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  1. Opening Questions • Why is DDT harmful? What effect of DDT (DDE) is linked to the slow decline of birds of prey in the United States during the late 1960s and early 1970s? • Does DDE accumulate in all species equally? Why not? What type of species is most likely to accumulate large amounts of DDE due to biomagnification? • When was DDT banned?

  2. Was the DDT ban effective in reducing the DDE concentrations in wildlife?

  3. Contains data concerning contaminants in mammals, birds, amphibians and reptiles that live near coastline or estuaries in the United States. • Created by scientists working for the Biological Resources Division of the U.S. Geological Survey, a part of the Department of the Interior of the United States Government. • Data in CEETV is mostly from articles published in peer-reviewed journals. Some data are from government reports and government websites.

  4. Tertiary Consumer There is a lot of data in CEETV, over 11,000 records on more than 400 species. What data do we need to examine if the DDT ban was effective? What type of species should we investigate?

  5. What factors should we consider before selecting a tertiary consumer to investigate? • Do all tertiary consumers have the same likelihood of accumulating high concentrations of DDE? • 2. Can we combine species or do we need to pick one? • 3. How much data is available?

  6. CEETV Data for DDE in Ospreys We have data on DDE concentrations in osprey eggs collected from various locations in the U.S. between 1968 and 1991. What question do we want to ask? What is our hypothesis? Hypothesis:In the two decades following the 1972 banning of DDT,DDE concentrations in osprey eggs did not consistently decrease in the United States below a harmful concentration(< 3ug/g ww). Our investigation is clearly defined: Species:Osprey Matrix (body part): Egg contents Location: United States Harmful concentration of DDE: > 3 ug/g ww Time frame: DDE concentrations < 3 ug/g ww by 1992

  7. DDE DDE DDE DDE Year Year Year Year We are going to investigate our hypothesis by graphing DDE concentrations in osprey eggs collected in the U.S. by year. What do we expect the graph to look like if the hypothesis is supported? What do we expect the graph to look like if the hypothesis is rejected?

  8. Individual data records Groups based on year Average DDE concentration for each group

  9. Sum of DDE concentrations of all individuals in the group Total number of individuals in the group Average DDE concentration for = each group

  10. DDE (ug/g ww average concentration) in Osprey eggs by Year

  11. The bald eagle, our National Bird and a symbol of freedom is also very sensitive to DDE! Adverse reproductive effects begin to occur when concentrations in bald eagle eggs reach about 3ug/g.

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