Biomagnification Through a Food Chain

Materials:

  • 100 M&M’s
  • Paper Towel for M&M’s
  • 20 small cups labeled zooplankton
  • 5 medium cups labeled minnow
  • 2 larger cups labeled eel 1 and eel 2
  • 1 bowl labeled osprey

Procedure:

  1. The pile of M&M’s represents the phytoplankton ( a small plant-like algae) population in a lake. The printed M on the candy represents the amount of DDT (in ppm – parts per million) the phytoplankton ingested from pesticide runoff from a nearby agricultural area. There are 100 M&M’s in the pile. Each circle below represents one phytoplankton. Mark the amount of each toxin each phytoplankton has ingested by doing the following:
  1. If there is a full M stamped on the candy, then that phytoplankton has ingested 1 ppm of DDT, so write a 1 in one of the circles below.
  2. If there is no M on the candy, then that phytoplankton did not ingest any DDT so write a 0 in one of the circles below.
  3. If there is a partial M on the candy then estimate how much of the M there is. For example, if there is only one hump of the M, then that would equal ½ a ppm of DDT ingested by that phytoplankton, so you would fill in one of the circles below with a ½.

1a. Using the numbers written on the phytoplankton above, add the amount of DDT each phytoplankton ingested to get the total amount of DDT ingested in ppm. Divide by 100 to get the average amount of DDT ingested by each phytoplankton. Write this number in column A on your data table.

1b. Now, in column B, write the total number of organisms at this trophic level by counting the phytoplankton.

1c. In column C, write the name of the trophic level/feeding relationship. You will use some terms more than once. Herbivore, primary consumer, top consumer, tertiary consumer, primary producer, secondary consumer, carnivore

2. Zooplankton in the lake (pictured below) each eat 5 phytoplankton. Move 5 M&M’s into each of the cups labeled Zooplankton. Now, look at the M&M’s in each cup and calculate the total amount of DDT ingested by adding up the M’s stamped on each M&M. Remember, if there is only ½ of an M pictured, you only add ½ ppm. As you calculate how much DDT each zooplankton ingested, write the total from the 5 M&M’s on each of the zooplankton pictured below. Each zooplankton should have a number written on it that ranges from 1-5.

2a. Now, to get the average amount of DDT ingested by each zooplankton, add the total amount of DDT ingested by each zooplankton. Divide the total by 20. Record this information in column A for zooplankton.

2b. For column B, add the total number of zooplankton by counting them.

2c. For column C, provide the names for this level.

  1. Minnows (population size of 5) in the lake each eat 4 zooplankton. Pour four zooplankton cups into each minnow cup. Count the ppm as before, and record the total amount of DDT ingested by each minnow, by writing the amount on the pictures below.

3a. For column A, add the amounts on the pictures above and divide by 5 to fill in the average amount of DDT ingested.

3b. Count the total number of minnows for column B.

3c. Write the appropriate labels for this trophic level in column C.

  1. Two eels then come along for dinner. Eel 1 eats 2 minnows and the Eel 2 eats 3 minnows. Move the correct number of cups from the minnows into the eel cups. Write the total amount of DDT on each eel below. One eel should have no more than 40 ppm, and the other eel should have no more than 60 ppm.

4a. Add the total amount of DDT ingested by each eel and divide the number by 2 to complete column A.

4b. Add the total number of eels for column B.

4c. Label the trophic level correctly for column C.

  1. Finally, an osprey flies by and eats both eels. Pour the eel cups into the osprey bowl. Write the amount of DDT on the osprey picture below.

5a. Complete columns A, B, and C.

Data Table:

A
Average amount of DDT Ingested (ppm)
By each organism / B
Numbers of Organisms / C
Name of trophic level/feeding relationship
Phytoplankton
Zooplankton
Minnow
Eels
Osprey
  1. Using column B, draw a pyramid of numbers. On your pyramid, write the names of the organisms at each level, as well as the numbers of organisms.
  1. Now, draw a pyramid showing the concentrations of DDT at each trophic level, using the information in column A. ***You may need an upside-down pyramid here. 
  1. Compare the amount of DDT found in the osprey with the amount of toxin found in one phytoplankton. Be specific. Discuss numerical evidence.
  1. Compare and contrast the numbers pyramid with the DDT pyramid. Write down the differences, while using numerical data.
  1. Why do you think a DDT pyramid displays the concept called BIOMAGNIFICATION? Think about how the DDT is moving up the food chain.
  1. Research how DDT has been used in the last 100 years. Give three examples of its use.
  1. Research two organisms that have been negatively affected by DDT and cite example of how the organism has been impacted.
  1. What are the current restrictions for DDT use?