• determine if different temperatures effect the growth and survival rates of aquatic plants.
• evaluate the optimal temperature for the growth of aquatic plants.

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

• Test tubes 1 & 2-Refrigerator or ice bath
• Test tubes 3 & 4-Incubator or light source
• Test tubes 5 & 6-Room temperature

Hypothesis:
 

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

Data Table:
 

After the observations are complete, answer the following questions
 

Conclusions:
1. Based on your observations, what would be the optimal 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. 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 this problem can be alleviated.