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Terraqua Column

Page history last edited by Hassan Wilson 14 years, 10 months ago

TAC Activities

 

 

Taking Inventory and Pondering Change

The TerrAqua Column that you’ve designed includes a variety of aquatic and terrestrial organisms. In a study system like this, it’s important to describe the living things that you stock it with before you introduce them into their habitats. “Taking Inventory” will assist you in doing this, and “Pondering Change” will help you predict changes that you think will occur as your TerrAqua Column develops over time.

 

Materials Required

 

Instructions

Taking Inventory

  1. Assemble the aquatic and terrestrial organisms to be introduced into your TerrAqua Column.
  2. Observe each item and identify it with a common and/or scientific name.
  3. Using your Taking Inventory Data Sheet (PDF), describe identifying and interesting characteristics for each organism.
  4. Take and record measurements of each organism.
  5. Make a sketch of each organism, including scale.
  6. Make a graphic inventory of your TerrAqua Column, showing where each organism is to be placed.

Pondering Change

  1. Use your Pondering Change Data Sheet (PDF) to make predictions about change in your TerrAqua Column over time.
  2. Set the length of the study period for your TerrAqua Column.
  3. At regular intervals during your study period, observe your TerrAqua Column and record changes that occur.
  4. At the end of your study period, make another graphic inventory.

 

Activity Questions

At the start of your study period

  1. What aquatic organisms will you introduce into your TerrAqua column?
  2. What terrestrial organisms will you introduce?
  3. Why did you choose these organisms?
  4. How would you describe diversity in your aquatic habitat? Your terrestrial habitat?
  5. What do you expect to happen in your aquatic habitat over time? Your terrestrial habitat?
  6. Do you expect to find “newcomers” in either habitat that you didn’t introduce?
  7. If so, what do you think these newcomers will be?
  8. How do you think newcomers might be introduced into each habitat?

At the end of your study period

  1. What types of changes occurred in your aquatic habitat? Your terrestrial habitat?
  2. What do you think caused these changes?
  3. Did you find any newcomers in either habitat? What were they? How did they get there?
  4. Were there any problems in either habitat?
  5. How would you change the design of your TerrAqua Column for future studies?

 

 

 

TAC Salt Experiment

 

Salt Pollution: Does salt affect plant growth?

Roads in Massachusetts* are salted in the winter to de-ice them, frequently with NaCl (sodium chloride), sometimes with CaCl2 (calcium chloride). The question arises whether the salt, carried by melt-water runoff from the road, affects plants growing in the vicinity, or aquatic systems where the runoff goes.

The following list of questions and answers provides you with a model for how you might set up an experiment with TACs.

What question are you exploring?

Are plants affected by runoff from roads de-iced with salt in the winter?

What specific idea (hypothesis) are you testing?

Higher concentrations of salt (NaCl) negatively affect plant growth.

What variable will you change in your experiment?

The concentration of NaCl in water fed to plants.

What variables will remain constant in your experiment?

Type of soil, water, and plants, age of plants, and salt treatment schedule. Physical conditions such as temperature and light.

List all the items you will need:

  • four TACs filled with 50 ml of water below and equal amounts of a potting soil above
  • seeds of grass, Fast Plants, radishes, or other fast-growing plants
  • four labels
  • salt – Use road salt, lab grade NaCl, pickling or kosher salt. Table salt often contains iodine and "flowing agents" that may affect results
  • eye dropper
  • soil testing kit to monitor soil pH (optional)

What is your experimental procedure?

  1. Plant seeds in four TACs.
  2. After plants have sprouted, label two columns CONTROL, label two 0.25% NaCl, and two 5.0% NaCl
  3. Prepare salt solutions of 0.25% and 5.0% salt by weight. (For example, 0.25% is one fourth of a gram of salt per 100 ml of water.)
  4. Treat each TAC with 10 ml of the appropriate salt solution. Use an eye dropper to place 5 ml on the soil and 5 ml in the reservoir. Treat the CONTROL with plain water.
  5. Treat plants every tuesday and friday day for a month.
  6. Observe and record plant development, including height, leaf number, size and color. You might also take pictures of the plants to monitor changes in color and other aspects of physical appearance. Keep track of the number of living snails and other organisms.
  7. Repeat this experiment, or run several at once. Can you reproduce your results?
  8. Upload your data to the TAC wiki on moodle.

Do the results of your experiment support your hypothesis?

*Adapted from http://www.bottlebiology.org/investigations/terraqua_explore.html

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