Name __________________________________________________________________ Date _________________________ Lab: Bioaccumulation and Biomagnification Introduction: Some toxic substances that are produced by industry or agriculture are not simply putting harmful materials into the atmosphere, but also our water supply and unwitting animals. During this lab we will examine the impact of the harmful toxin “MMT” on our fragile ecosystem and food chain. There are two types of pollutants that can enter an ecosystem. Persistent pollutants, which accumulate in an organisms fatty tissue; and non-­‐persistent pollutants, which are water-­‐soluble and therefore, pass through an organisms body when it excretes sweat, urine, or feces. When a producer comes in contact with a persistent pollutant, it accumulates in the tissue of the organism; when animals eat organisms (plants or other animals) that have these persistent pollutants in their tissue, it accumulates in the tissue of the consumer by a process called bioaccumulation. The higher an animal is on the food chain, the greater the concentration of pollutant in their body. This strengthening of the pollutant as you move up the food chain is called biomagnification. !!!!! HOLD UP !!!!! Ecology Review – What are other examples of animals at these trophic levels What does a trophic level represent? How does energy flow through the food chain? Quaternary Consumers: Tertiary Consumers: Secondary Consumers: Primary Consumers: Primary Producers: Name __________________________________________________________________ Date _________________________ Prelab: Look at the animals for our lab today and fill in the marine food chain Phytoplankton: acquire toxic chemicals from industrial plants Procedure: 1. You will receive both a krill card and a second animal card. Tape these to your plastic bag or beaker. These are the animals you will represent throughout this experiment 2. Go to the area designated for the experiment. The beads/M&M’s scattered throughout the area represent phytoplankton. *oops, the factory nearby has pretty harmful smoke pouring out, and some of the phytoplankton may be toxic! 3. Begin with the bag/beaker labeled as “krill”. On the signal, you will have 2 minutes to move around the area and “eat phytoplankton”. This will be symbolized by picking up the beads/M&M’s. 4. At the end of 2 minutes, the small fish will be released and begin to eat – for 1 minute. The small fish eat only the krill. They do not eat the phytoplankton. To eat a krill, a student wearing a small fish card takes the krill’s bag of food. Krill may continue to eat throughout this time 5. After the small fish have been eating for 1 minute, the penguins will be released and begin to eat only the small fish. Penguins do not eat krill or phytoplankton. To eat a small fish, students who are “penguins” take the small fish’s bag(s) of food. a. Eaten small fish must sit down on the ground and remain there through the exercise. b. Living small fish may continue to feed on krill c. Living krill may continue to grade on phytoplankton 6. After the penguins have been eating for 1 minute, the seal will be released and begin to eat for 1 minute. The seal eats penguins only. It will not eat small fish, krill, or phytoplankton. a. Eaten small fish and penguins must sit down on the ground and remain there through the exercise. b. Living penguins may continue to feed on small fish c. Living small fish may continue to feed on krill d. Living krill may continue to grade on phytoplankton 7. At the end of this minute, the experiment ends and everyone stops moving. 8. Students who represent living organisms should move to one side of the area and sit as a group. Living organisms should examine and record the contents of their bags to determine how much toxin each animal consumed. To do this, each living organism should: a. Pour all of the beads/M&M’s from all of the bags in their possession onto a sheet of paper. Count all of them and record this number in data table 1. We will collect class data to complete this table b. Count the ___________________ and ___________________ beads/M&Ms and write the total number of these colors (separately and together) on the data table. These represent the toxins released by the factory. Name __________________________________________________________________ Date _________________________ Data: Toxic algae accumulate in the bodies of animals that eat them. If as much as 25% of the food an animal eats is toxic, that animal will die. Calculate the percentage of toxic food consumed by living animals with this formula: % Toxic Food = (# Total Toxic M&Ms / Total number of M&Ms) x 100 Data Table 1. Percentage of toxic Lived/ food Died consumed Total Number of M&Ms Organism Name Number of _____ Total Toxic M&Ms Number of _____ Data Analysis: Trophic Level Animal % Concentration of Toxin (average) Producers Primary Consumers Secondary Consumers Tertiary Consumers Quaternary Consumers Name __________________________________________________________________ Date _________________________ 1. How did the % concentration of toxin change as we went from the bottom of the food chain to the higher trophic levels? Did that match your predictions? Why or why not? 2. If the colored M&Ms represents Mercury (a persistent pollutant) first absorbed by the producers, which of the following groups are most susceptible to problems from Mercury: primary producer, primary consumer, secondary consumer, 3rd order consumer, or 4th order consumer? Why? 3. Challenge: The sea lamprey is considered an apex predator in most Great Lakes food chains because it has no natural predators, however it is NOT affected by DDT (a pesticide which is a persistent pollutant) as other apex predators would be. Why? Think about the diet of the sea lamprey! 4. Consider the two following food chains: Food chain 1: flagellates à opossum shrimp à rainbow trout Food chain 2: flagellates à opossum shrimp à alewife à rainbow trout How might the differences in these food chains result in exposure to different amounts of DDT? 5. Distinguish between a persistent pollutant and a non-­‐persistent pollutant. Name __________________________________________________________________ Date _________________________ 6. Suppose an average Midwesterner eat 300g of yellow perch per month. If the fish tissue consumed by the human has an average concentration of 0.1μg/g (micrograms Mercury per gram of tissue), how much DDT is the human consuming per year? Show your work! 7. Now suppose the same person eats 300g of lake trout per month. Since the lake trout is higher on the food chain, the fish tissue consumed has an average concentration of 2.0 μg/g. How much DDT is the human consuming per year? Show your work! 8. An LD50 value is the mean lethal dose. This means that half of the organisms that have ingested or been exposed to a dosage equal to the LD50 will die. The rat oral LD50 for Mercury is 41 mg/kg (milligrams of Mercury per kilogram of tissue). Would consuming 300g of lake trout be enough to kill a rat? Show all work and remember to convert units! 9. DDT is a pesticide that has been banned in the United States since the 1970s, yet the Center for Disease Control has found concentrations in nearly ALL human blood sampled in 2005. a. Would this make it a persistent or non-­‐persistent pollutant? Describe its path through an organism (is it stored or excreted?) and the food web (does it accumulate or not?). b. Why do we still find DDT in human blood? Use the terms bioaccumulation, biomagnification, and nutrient cycles in your response. What implications does this have on the long-­‐term health of humans and other organisms that come in contact with this chemical? Name __________________________________________________________________ Date _________________________