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3.05 Water Quality/Bioassessment Lab

Directions: Use Accessing Water Quality Virtual Laband complete the simulated lab on using bioassessment to determine water quality. In this lab, you will learn how water’s pH level affects 10 different macro-invertebrates. Follow the procedure steps below carefully, complete the chart on page two, and then answer the questions.

Procedures:

  1. Click on Information at the bottom of the screen and read more about pH and using bioassessment to determine water quality.
  2. Examine the aquarium. Three invertebrates have been randomly chosen for you to begin the lab. Notice the pH of the water starts with 7.0.
  3. Click on the computer on the desk and record the number of each organism at the 7.0 pH level in the chart below.
  4. Click on the dropper in the 1% Carbonic Acid. This will add three drop of acid to the aquarium.
  5. Record the pH and number of organisms after adding the three drops. (You can see the number of organisms by clicking on the computer on the desk).
  6. Continue adding drops of carbonic acid and recording the pH and number of organisms until you have the data for pH of 2.8.
  7. After completing the test for the 1st invertebrates, click the reset button to randomly choose the next 3 organisms.
  8. Record the data for each pH level in the chart below.
  9. Complete steps 1-7 until all 10 organisms have been tested.

pH / Aquatic
Earthworm / Snail / Tubifex
Worm / Clam / Leech / Sideswimmer / Dragonfly
Nymph / Crayfish / Fairy
Shrimp / Stonefly
Nymph
7.0
6.7
6.4
6.1
5.8
5.5
5.2
4.9
4.6
4.3
4.0
3.7
3.4
3.1
2.8

Use your data and the information you learned in the lab to answer the following analysis questions.

  1. Which organism was the most tolerant to the increase in acidity? Which organism was the least tolerant to the increase in acidity? (Hint: pH increases as the number gets lower.)
  2. According to the information, what causes acid rain? What is the typical pH of acid rain?
  3. What is an indicator species? From the lab you just completed, which organism(s) would you consider an indicator species?
  4. If you were an ecologist studying the effects of acid precipitation on plant life, describe how you might design an experiment to determine a good indicator species of plants.
  5. What other water quality characteristics could an indicator species identify according to the Information tab?