BIO 104 Answers_to_Biomagnification_Lab

Lab Report > BIO 104 Answers_to_Biomagnification_Lab_2018

Name BiomagnificationHidden Dangers in Food Webs Purpose: To observe how toxins such as DDT and PCB can accumulate in organisms within a food web. Materials: dog food with varying colors, gr ...[Show More]

Name

Biomagnification

Hidden Dangers in Food Webs

Purpose: To observe how toxins such as DDT and PCB can accumulate in organisms within a food web.

Materials: dog food with varying colors, grassy space for a game of tag

Introduction:

Many chemicals produced by industries end up in our waterways through dumping or runoff.

Many of these chemicals can accumulate in the cells of organisms that live in the water. These chemicals then move up through the food chain and can be damaging or fatal to many types of organisms. Although the initial level of these chemicals might be low, the concentration of these chemicals can increase/magnify as they move up food chains. This is known as biomagnification.

DDT (dichlorodiphenyl-trichloroethane) was the first commonly used insecticide. DDT was relatively inexpensive to manufacture and had long-lasting effects. DDT enters plants as they take it in while obtaining water for photosynthesis. DDT is harmful to many organisms as it attacks the nervous system of animals. Furthermore, it also has adverse effects on many seabirds. DDT prevents proper eggshell production in birds, which results in very brittle eggs which are then easily broken. This greatly reduces the rate of successful reproduction for these birds.

Procedure:

1. Randomly spread dog food with at least 2 different colors (simulating grass) into an open space.

2. The students selected to be rabbits will have 2 minutes to collect as much dog food (grass) as they can.

3. Now the “snakes” will be released to chase the rabbits. If a rabbit is caught, they will give their bag of dog food/grass to the snake that caught them and remove themselves from the game.

4. Next, the “hawks” will be released to chase the remaining rabbits and the snakes. Any “animal” that is tagged will need to give all of their food bags to the hawk that caught them and then remove themselves from the game.

5. Upon returning to the classroom, each “animal” that is still alive will count the number of toxic/red pieces of dog food in all of their bags combined.

6. As a class, Calculate the average amount of DDT/toxin for each species type.

a. For example:

Amount of DDT per organism

Analysis Questions:

1. In the space provided below, construct a food chain to illustrate the flow of energy between the organisms used in this simulation.

Plants à rabbits à snakes à hawks

2. What happened to the amount of DDT per organism as you move up the food chain?

The amount of DDT increases as you move up the food chain.

3. Which organism contained the largest concentration of DDT? The Hawks (the largest predator) contain the largest concentration of DDT because they eat the other animals where the toxin has built up.

4. Why is DDT harmful to hawks? (What does it prevent them from doing successfully?) The DDT prevents the hawks from reproducing successfully. It softens the eggs so that the babies are born too early and cannot survive.

5. The organisms used as examples in this activity are common in a NY ecosystem in North America. Using the information below construct a food web of a typical NY ecosystem in the space provided below.

6. What is one other organism besides hawk that you would expect to have high concentrations of DDT? Explain your answer.

7. If the hawk population were to decrease due to DDT, what are two other populations that would be affected and how?

Thinking further:

The following diagram illustrates a typical marine food web. Mercury, a toxic heavy metal, can accumulate in the fatty tissue of organisms.

Mako Shark