APES

Biomagnification Visualization

Introduction:

Bioaccumulation is when an organism accumulates a material in its body at a concentration greater than the environment. Biological Magnification occurs when bioaccumulation happens in several links in a food chain. A consumer (of any level) has to consume a lot of biomass from the lower trophic level in order to survive. If that biomass contains the pollutant, the pollutant will be taken up in large quantities by the consumer. Biomagnification can happen when:

  1. The material is long-lived (does not degrade, or is not easily broken down by organisms).
  2. The material is concentrated in the organism’s body (is not excreted).

This often occurs with pollutants that are soluble in fat. Water-soluble pollutants usually do not magnify because they dissolve in the bodily fluids of the consumer. Examples of Biomagnification include organic compounds like DDT or PCBs, and heavy metals. In the 1960’s scientist Rachel Carson published “Silent Spring” which led to the banning of DDT, the search for pesticides that would not biomagnify, and the birth of the “modern” environmental movement.

Video:

Materials:

Dice

Silver paper clips = (humans)

Red paper clips = (fish)

Blue paper clips = (zooplankton)

Green paper clips = (algae)

Black paper clips = (mercury)

Procedure: What if you could see all the chemicals you were eating?

  1. READ the introduction above!
  1. You will be looking at a simulated food chain between algae, zooplankton, Fish, and Humans. On your own sheet of paper construct a trophic level pyramid for the given organisms. Make sure to label each trophic level (ex: primary consumer etc.)
  1. Create a data table to record how much mercury accumulates in each trophic level.
  1. We will start by assuming that each alga accumulates 2 units of mercury. So start by placing 2 black paper clips on 1 green paper clip (simulating 2 units of mercury per unit of algae).
  1. Each zooplankton needs to consume 2 algae to stay alive. Attach 2 algae (green) to 1 zooplankton (blue). Remember that each alga comes with 2 units of mercury!
  1. Now in real situations competition and chance are involved so we will roll a dice to see how many zooplanktons each fish (red) in our chain consumes. If you roll a 1-3 then your fish consumes 2 zooplankton. If you role a 4-6 then each fish consumes 3 zooplankton. Remember you must include all previous levels of materials!
  1. Follow the procedure for number 5 to figure out how many fish each human consumes in your food chain. Remember you must include all previous levels of materials!
  1. Use your data table to create a bar graph comparing the amount of mercury in each trophic level.
  1. Take all paper clips apart from each other and return all materials to the bag you received. Answer the questions on the back of this paper in complete sentences.

Discussion Questions

  1. What is the difference between bioaccumulation and biomagnification?
  1. What are 2 situations in which biomagnification can happen?
  1. What are some examples of pollutants that can biomagnify?
  1. Why are compounds that are soluble in water not likely to biomagnify?
  1. Which trophic level was most affected by biomagnification?
  1. This simulation showed just one path in a food chain. In real life over many years would this affect be greater or smaller over many years of feeding?
  1. Use what you have learned to explain how a very small amount of a dangerous chemical can become very dangerous.
  1. Would you expect a fish that is a carnivore or an herbivore to contain more mercury? Why?
  1. Example from page 75 (There are multiple species for numbers 3 and 4)