The Importance of Temperature : Will a fluctuation in temperature effect the growth and survival rate of aquatic plants?

Objectives:

Students will be able to:

  • determine if different temperatures effect the growth and survival rates of aquatic plants.
  • evaluate the optimal temperature for the growth of aquatic plants.
    Note: Safety goggles and aprons should be worn at all times during this lab activity.


    • Materials:
    Fresh water sample from a local pond or aquarium
    6 test tubes
    6 portions of duckweed or elodea
    3 thermometers
    3 beakers or test tube racks to hold test tubes
    hand lens or dissecting microscope
    Petri dishes
    Refrigerator (preferable) or ice bath
    Incubator or light source

    Procedure:
    Working with a partner:
    1. Using a hand lens or a dissecting microscope, examine a portion of the plant to be used
    in this experiment.
    Describe the characteristics of a healthy plant.

    2. Label 6 test tubes as follows:

    2 Test tubes - 1 & 2
    2 Test tubes - 3 & 4
    2 Test tubes - 5 & 6
    3. Fill each test tube approximately half full with the fresh or aquarium water sample.
    4. Add a sprig of the plant to each test tube.
    5. Place the test tubes in a rack or a beaker and place each group of two in the appropriate
    location.
    Test tubes 1 & 2-Refrigerator or ice bath
    Test tubes 3 & 4-Incubator or light source
    Test tubes 5 & 6-Room temperature
    6. Place a thermometer in each location as close as possible to the test tubes.
    7. Take a temperature reading from each location after approximately 10 minutes. This
    will allow time for the temperature to stabilize.
    8. Record the temperature readings in the data table under Day 1.
    9. Based on your knowledge of aquatic ecosystems and temperature, hypothesize how the
    cultures will change over a 24 hour period.
    Hypothesis:

    10. Record each of the temperature readings and observations on the data table for the next four
    days.

    Data Table:

    Day Observations on tts 1 and 2 in refrigerator Temp of tts 1 and 2 Observations on tts 3and 4 in light source Temp of tts 3 and 4 Observations on tts 5 and 6 at room temperature Temp of tts 5 and 6
    1

     

     

    		          
    2

     

     

    		          
    3

     

     

    		          
    4

     

     

    		          
    5

     

     

    		          



    When you have finished your observations, answer the following questions

    Conclusions:
    1. Based on your observations, what would be the optimal (best) temperature for the growth and
    development of aquatic plants?

    2. Based on your observations, what would happen to plants in an aquatic ecosystem if the
    temperature increased or decreased?

    3. How would this effect the aquatic ecosystem as a whole? (Consider other organisms
    such as macroinvertebrates and fish)

    4. Go on the web and research the effects of thermal pollution on aquatic plants. Write a short paragraph
    explaining what thermal pollution is and how it effects an aquatic ecosystem. In addition,
    include how you would alleviate (reduce the effect) this problem.