Lesson 10 Food Webs in Action

Transcription

1 Lesson 10 Food Webs in Action Classroom Activities and Procedures Part 1 Phytoplankton and Marine Animals Objectives To construct a sample marine food web. To explain the importance of phytoplankton in the food web. May 2003 Phytoplankton Northern Right Whale Sightings Spring 2003 The images above show sightings of northern right whales together with average chlorophyll concentrations for March and May. Off the coast of New England in May, notice there are many sightings near very high phytoplankton areas. Northern right whales do not eat phytoplankton, however. These animals use broom-like plates in their mouth called baleen to filter zooplankton and small fish out of the water. March 2003 Phytoplankton NOAA CoastWatch, NASA GSFC, OceanColor Web S-125

2 Part 2 From Tiny to Tremendous: Marine Food Webs Carefully follow the instructions below with your group. 1. Use the organism cards to build the connections between organisms. Each card has the name, picture of the organism, and information about what the organism eats and/or is eaten by. Begin with the different types of phytoplankton because they use the Sun s energy to make food. Place the phytoplankton cards near the bottom of a blank piece of poster paper. Draw the Sun near the phytoplankton, and draw an arrow from the Sun to the phytoplankton to show that the energy is transferred from the Sun to the phytoplankton. 2. Read through the cards and determine which consumers eat the phytoplankton. This means that these organisms are getting energy from the phytoplankton. Place these cards on the poster above the phytoplankton and use arrows to indicate the flow of energy. 3. Continue to add the different cards to the poster and connect them using arrows. Remember that the arrows show the direction in which the energy flows. There may be one or many arrows connected to a single organism. 4. Once all of the organisms are connected, glue the cards to the poster. The diagram your group created represents the transfer of food energy within a community of organisms. This diagram is known as a food web. S-126

3 Now, use the poster and the following information to answer the questions below: 1. What is the source of energy for this food web? 2. Fishermen believe that they compete with seals. Why do they believe this to be true? 3. There is growing concern that some fish species are being overfished. Overfishing means that people who fish are catching too many of a fish species; the species does not have time to replenish itself. For example, if people who fish catch many young fish before they reproduce, the species will not be able to sustain itself. By looking at the food web, predict what would happen if herring were overfished. 5. Is this a complete food web? Why or why not? S-127

4 6. What would happen if there were no energy source for the food web? 7. Why are phytoplankton often called the base of the food web? 8. If the amount of phytoplankton in an area decreased, what do you predict would happen? 9. How might some of the larger consumers cope with less phytoplankton in an area? S-128

5 Part 3 Putting it Together May Why is it important to look at chlorophyll (phytoplankton) imagery when tracking marine animals? March Why are phytoplankton important to northern right whales? 3. In an area with a low concentration of phytoplankton, would you expect a lot of biodiversity? Why or why not? S-129

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