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Something Fishy…Do Now

Something Fishy…Do Now. How much seafood do you eat in the average week? What types? Are there any dangers associated with eating seafood?. Objective. Students will be able to… explain how mercury enters the food chain list health effects of high levels of mercury on humans

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Something Fishy…Do Now

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  1. Something Fishy…Do Now How much seafood do you eat in the average week? What types? Are there any dangers associated with eating seafood?

  2. Objective Students will be able to… • explain how mercury enters the food chain • list health effects of high levels of mercury on humans • Explain the difference between bioaccumulation and biomagnification.

  3. Mercury The Minimata Disease http://www.youtube.com/watch?v=ihFkyPv1jtU

  4. Tuna for Lunch? A Case Study Examining Mercury Bioaccumulation and Biomagnification By Caralyn B. Zehnder Department of Biological and Environmental Sciences Georgia College and State University, Milledgeville, GA

  5. Lesson Outline- Key Questions 1. How does mercury get into the food chain? 2. What is the EPA limit for mercury? 3. What are the factors that determine how much mercury an animal has in it? 4. What part of the population needs to be the most careful about ingesting mercury? 5. Is mercury the only substance with this type of problem?

  6. How does mercury get into the food chain? • ___________is the most common source of mercury pollution • Natural sources of mercury are: _____ Group 2

  7. Coal-burning power plants most common source Coal contains mercury naturally  burned released into the air.

  8. How does mercury get into fish? Group 2

  9. Start Here! Hg – in emissions (smoke) Hg - Deposited on land and into water Bacteria 50-75% from human sources Methyl-mercury (MeHg) MeHg Zooplankton MeHg Large fish MeHg Small fish Phytoplankton (algae) MeHg

  10. What’s the deal with MeMg? Form of Mg determines toxicity. Effects: • Immune system • Alters genetic enzymes • Damages nervous system • Sense of touch, taste, and sight. Doesn’t eliminate quickly

  11. Each and every fish tested from nearly 300 water streams in the U.S. was found to contain mercury. Group 1 Fish to look out for?...Help us out!

  12. Figure 1: Mercury concentrations (ug/g) found in fish tissues of commonly sampled fish species. Group 2

  13. Mercury concentrations (ug/g) found in fish tissues of commonly sampled fish species. US EPA criterion for human health.

  14. Factors that determine mercury concentration… • How much food containing mercury the animal eats • Eating food without mercury • How long the animal has lived • Biaccumulation • How high in the food chain it is • Biomagnification Group 3 & 4

  15. Bioaccumulation Bioaccumulation: The buildup of substances, such as pesticides or heavy metals, in an organism. Absorbing faster than excreting Mercury out Mercury in Group 4

  16. Biomagnification An increase in concentration of a pollutant from one position in the food chain (trophic level) to the next. If a substance can biomagnify: animals (predators) at the top can have higher concentrations than animals lower on the food chain. Group 4

  17. Just another way to look at it… What does the relative size of each rectangle represent in this diagram?

  18. An anchovy eats zooplankton that have tiny amounts of mercury in them. The anchovy eats many zooplankton, accumulating the mercury of each over its life. A tuna then eats many of these anchovies over its life, accumulating the mercury of each of those anchovies into its body. This continues up the food chain, with the concentration increasing each time.

  19. Which would you predict to have a higher level of mercury?

  20. Size vs. Trophic level Why might two types of animals that are very different in size have the same level of contamination? They are on the same level of the food chain Group 3&4

  21. Bioaccumulation vs. Biomagnification Bioaccumulation is the increase of toxins within an organism Biomagnification is the increase of toxins between organisms of different trophic levels. Group 3

  22. Who should be most careful? Group 1 & 2 Because…Possibility for nerve damage in developing brains

  23. Is Mercury the only example of bioaccumulation? DDT insecticide Birds ate infected bugs ->largest birds were harmed the most Eagle Egg shells too weak to protect the growing eaglet.

  24. How much mercury do you have in you? Calculate your mercury intake: http://www.nrdc.org/health/effects/mercury/calculator/start.asp

  25. Write a 3 sentence explanation of this picture using the terms bioaccumulation and biomagnification.

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