"Tuna for Lunch" Case Study
Part 1:
1) What is in some fish and shellfish that has caused the EPA and FDA to issue the restriction for pregnant women and for young children?
Mercury
2) Why is there a restriction for pregnant women and young children, but not the rest of the population?
If a pregnant women consumes mercury it can be passed to their unborn child and can affect their health or development.
3) Do pregnant women have to avoid all fish? Explain your answer.
No, women only have to avoid the fish that their doctor tells them to because it has a high amount of mercury in that certain fish.
4) Should Amanda have avoided the pan-seared tuna for lunch?
Yes, she should have avoided the pan-seared tuna for lunch as a precaution to her unborn child.
5) Why is eating fish good for you? Do you want to avoid fish all together? Why or why not?
Fish is a good for you because it is a good source of protein. No, you don't want to avoid fish all together, just certain fish that doctors recommend you not to eat because of the high amount of mercury in them.
Part 2:
1) What human actions lead to increased Mercury levels in the environment?
Coal-burning power plants
2) How does the Mercury end in fish? DRAW a flow chart following the Mercury path.
Fish take in the water contaminated with mercury.
1) What is in some fish and shellfish that has caused the EPA and FDA to issue the restriction for pregnant women and for young children?
Mercury
2) Why is there a restriction for pregnant women and young children, but not the rest of the population?
If a pregnant women consumes mercury it can be passed to their unborn child and can affect their health or development.
3) Do pregnant women have to avoid all fish? Explain your answer.
No, women only have to avoid the fish that their doctor tells them to because it has a high amount of mercury in that certain fish.
4) Should Amanda have avoided the pan-seared tuna for lunch?
Yes, she should have avoided the pan-seared tuna for lunch as a precaution to her unborn child.
5) Why is eating fish good for you? Do you want to avoid fish all together? Why or why not?
Fish is a good for you because it is a good source of protein. No, you don't want to avoid fish all together, just certain fish that doctors recommend you not to eat because of the high amount of mercury in them.
Part 2:
1) What human actions lead to increased Mercury levels in the environment?
Coal-burning power plants
2) How does the Mercury end in fish? DRAW a flow chart following the Mercury path.
Fish take in the water contaminated with mercury.
3) Where in the United States are Mercury wet deposition levels highest? What do you think explains this pattern?
Missouri, Arkansas, Tennessee, Florida because they have the most coal-burning power plants.
4) The EPA criterion for human health is 0.3 ug/g. Which fish species have average concentrations that exceed the EPA limits?
Large mouth and Spotted Bass
5) The concern level for piscivorous (fish-eating) mammals is 0.1 Hg ug/g. Which fish species have average mercury concentrations that exceed this limit? Why is the mercury level for piscivorous mammals lower than the level for human health?
Trout and bass exceed the limit. Mercury level is lower than in human health because the animal might not have been able to resist mercury as much as humans.
6) Should you be concerned about mercury toxicity if you catch and eat a largemouth bass in a local lake? Why or why not?
Yes, because largemouth bass has a high level of mercury.
7) In which samples were mercury concentrations the highest (fish, streams, or sediment)? Why do you think this is?
Sediments, because it can be in both ground and water, making it absorb more mercury.
Part 3:
1) Draw a food web for Lake Washington using the species and food preferences given in Table 3. Start with phytoplankton (algae) as the base of your web and then build up the food chain.
2) Label the species in your food chain as either high (>100 ug/kg), medium (20-100 ug/kg), or low (below 20 ug/kg) mercury concentrations. Which types of animals have the highest levels of mercury? Which types of animals have the lowest? Why do you think this is?
The big fish have the highest levels of mercury. The phytoplankton have the lowest. The fish have higher levels because of biomagnification.
Missouri, Arkansas, Tennessee, Florida because they have the most coal-burning power plants.
4) The EPA criterion for human health is 0.3 ug/g. Which fish species have average concentrations that exceed the EPA limits?
Large mouth and Spotted Bass
5) The concern level for piscivorous (fish-eating) mammals is 0.1 Hg ug/g. Which fish species have average mercury concentrations that exceed this limit? Why is the mercury level for piscivorous mammals lower than the level for human health?
Trout and bass exceed the limit. Mercury level is lower than in human health because the animal might not have been able to resist mercury as much as humans.
6) Should you be concerned about mercury toxicity if you catch and eat a largemouth bass in a local lake? Why or why not?
Yes, because largemouth bass has a high level of mercury.
7) In which samples were mercury concentrations the highest (fish, streams, or sediment)? Why do you think this is?
Sediments, because it can be in both ground and water, making it absorb more mercury.
Part 3:
1) Draw a food web for Lake Washington using the species and food preferences given in Table 3. Start with phytoplankton (algae) as the base of your web and then build up the food chain.
2) Label the species in your food chain as either high (>100 ug/kg), medium (20-100 ug/kg), or low (below 20 ug/kg) mercury concentrations. Which types of animals have the highest levels of mercury? Which types of animals have the lowest? Why do you think this is?
The big fish have the highest levels of mercury. The phytoplankton have the lowest. The fish have higher levels because of biomagnification.
Part 4:
1) Imagine you are Tara. Write a letter to your friend Amanda explaining what you have learned about mercury. Be sure to convey the aspects of your learning that will be most useful to Amanda.
Dear Amanda,
There are many fish in the sea, but certain ones are to keep away from. There are many fish that contain mercury in them and if consumed, can cause health problems. If you are pregnant it is especially important to not consume any fish that contain mercury because it can be transferred to you're unborn child and can cause health problems. Mercury usually comes from coal-mining power plant. If fish live near these power plants then they will contain mercury. Due to biomagnification, the larger the fish, the more mercury it has in it. Mercury is very dangerous and we need to be careful with what we are consuming.
Sincerely, Selena
2) Find two other samples of compounds that biomagnify. Explain how each compound and/or toxin enters the biosphere and what impacts it has on living organisms in general and humans in particular.
DDT- Enters the biosphere from the humans spraying it in their crops. Causes headache, nausea, vomiting, confusion
Cyanide- Enters the biosphere by putting it in the water. Causes paralysis and miscarriages.
3) Distinguish between bioaccumulation and biomagnification and design a mnemonic device for the distinction
Bioaccumulation- Buildup of toxic chemicals.
Biomagnification- Concentration of a toxic magnifies when a larger organism eats an organism with toxic chemicals.
Distinction: Bioaccumulation>Accumulation>Accumulate>Build up
Biomagnification>Magnification>Magnify>Boost
1) Imagine you are Tara. Write a letter to your friend Amanda explaining what you have learned about mercury. Be sure to convey the aspects of your learning that will be most useful to Amanda.
Dear Amanda,
There are many fish in the sea, but certain ones are to keep away from. There are many fish that contain mercury in them and if consumed, can cause health problems. If you are pregnant it is especially important to not consume any fish that contain mercury because it can be transferred to you're unborn child and can cause health problems. Mercury usually comes from coal-mining power plant. If fish live near these power plants then they will contain mercury. Due to biomagnification, the larger the fish, the more mercury it has in it. Mercury is very dangerous and we need to be careful with what we are consuming.
Sincerely, Selena
2) Find two other samples of compounds that biomagnify. Explain how each compound and/or toxin enters the biosphere and what impacts it has on living organisms in general and humans in particular.
DDT- Enters the biosphere from the humans spraying it in their crops. Causes headache, nausea, vomiting, confusion
Cyanide- Enters the biosphere by putting it in the water. Causes paralysis and miscarriages.
3) Distinguish between bioaccumulation and biomagnification and design a mnemonic device for the distinction
Bioaccumulation- Buildup of toxic chemicals.
Biomagnification- Concentration of a toxic magnifies when a larger organism eats an organism with toxic chemicals.
Distinction: Bioaccumulation>Accumulation>Accumulate>Build up
Biomagnification>Magnification>Magnify>Boost