Tuna For Lunch
Directions: Read the case study and answer the following questions on your scrAPES website as STATEMENTS, not simply answering the questions number by number.
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 has caused the EPA and FDA to issue restriction for pregnant women and children due to its toxicity.
2: Why is there a restriction for pregnant women and young children, but not the rest of the population?
Mercury causes birth defects for babies in the wmb and problems within the nervous system of young children and even cause learning defeciencies, whose bodies are still maturing.
3: Do pregnant women have to avoid all fish? Explain your answer.
No, women should avoid fish that feed higher up the food pyramid; due to biomagnifcation, it is safe to eat fish that comes from the lower side of the food chain because the fish hcontains less concentration of the toxin hence not harmful to the baby.
4: Should Amanda have avoided the pan-seared tuna for lunch?
Amanda should have avoided the pan-seared tuna because tuna are very high on the food chain which means that biomagnification has occured and it contans a lot more toxns that harms the body.
5: Why is eating fish good for you? Do you want to avoid fish all together? Why or why not?
Fish should not be avoided altogether because it is high in vitamins and nutrients that are essential to human health often it is less containated than meat; however there are still hazardous effects if one is not aware of the type of fish hey are eating.
1: What human actions lead to increased Mercury levels in the environment?
Fossil fuel burning is one of the main contributors to increasing levels of mercury in the atmosphere
2: How does the Mercury end in fish? DRAW a flow chart following the Mercury path.
3: Where in the United States are Mercury wet deposition levels highest? What do you think explains this pattern?
Missouri, Arkansas, Tennessee, and Florida have the highest levels of Mercury wet deposition because these areas have many 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?
The Largemouth 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?
The Trout and Bass exceeded the limit. The mercury level is lower than it is for human health because the animals are more vulnerable to mercury than humans are
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 it could have high levels of mercury bioaccumilated within its body
7: In which samples were mercury concentrations the highest (fish, streams, or sediment)? Why do you think this is?
Sediment samples had the highest concentration of mercury because it can be in the ground and water.
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?
Large fish have the highest level of mercury. Phytoplankton have the lowest. Biomagnification cause larger fish to have higher concentrations.
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.
Mercury occurs naturally in the environment, and is emitted into the atmosphere from volcanic smoke. Human activities, such as coal-burning and power plants, have ignificantly increased mercury emissions. Once it enters the atmosphere it is precipitated through rainfall and enters the environment. Because it is naturally occurring in the atmosphere, it is only harmful in large amounts causing learning disabilities in children. Larger doses of Mercury have been known to have dangerous impacts on the nervous system of young children and cause birth defects on developing fetuses. In recent years aquatic organisms have been exposed to mercury deposits into their water. Organisms bioaccumulate mercury into their bodies through biomagnification. Mercury is biomagnified up the food pyramid, and evntually enters the part of the food chain where the people consume it. Larger fish should be avoided because of their higher accumulation of Mercury, and should especially avoided childre and pregnant women to prevent toxicity.
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.
Arsenic- occurs naturally and from industrial activity or through desired use (pesticide, medicine, or feed additive). It can cause cancer in the skin, lungs, bladder and kidney, and skin changes such as thickening and pigmentation.
DDT- Used on crops, and is known to cause headache, nausea, vomiting, and confusion. DDT has also been known to cause distilled births for many organisms
3: Distinguish between bioaccumulation and biomagnification and design a mnemonic device for the distinction
Bioaccumulation= bio + accumulation (mu→ more); an individual acquiring more toxin within its body
Biomagnification= bio + magnification (magnifiying glass makes things bigger→ bigger organisms have more toxin than prey)