Unit 3 (part 5): Monitoring Water Quality through the use of Algae
Concepts: Algae can be used as an indicator of level of organic pollution in a
water sample.
Objectives:
1. Students will observe and identify certain types of algae associated with
water pollution.
2. Students will use an algal pollution index to determine the level of organic
pollution in a water sample.
Summary:
Students will collect water samples from a predetermined site. Samples will be
brought back to the laboratory for careful examination. Water quality of the
samples will be determined by the types and quantities of algae present.
Teacher Notes:
Site Location
Class instructor should locate (and gain permission to sample) one of the following
scenarios for this investigation.
Scenario 1. Two stream comparison
1. Identify two different, but similar sized streams. Each stream should be
shallow, wadeable, and have a riffle habitat(s) for students to investigate.
One stream should be relatively healthy (i.e., good riparian corridor, rocks
without sediments covering them) and the other impacted/impaired (i.e., no
riparian corridor, heavy sediment load).
2. Make certain that you have permission from the neighboring land owner(s)
to sample.
3. Enter the sample location downstream from the riffle(s) that you will be
sampling.
4. Work your way to the riffle site carefully and visually inspect the rocks for
algal specimens. Be careful to disturb the streambed as little as possible.
© 2010, Ohio Northern University: Dr. Debra Gallagher, Dr. Robert Verb, Dr. Ken Reid and Ben McPheron
5. If measurements of water quality are to be done (i.e., pH, specific
conductance), please take samples before disturbing the site.
6. Large filamentous algal forms can be collected by hand or with forceps and
placed in a bag/container (with some stream water) for transport back to the
lab.
7. Have students pick five rocks out of the riffle and transport them to the bank
for processing.
8. A known area (e.g., 5 cm x 5 cm) should be scrapped or brushed to loosen
the attached algal mat. Use stream water to rinse the loose algae into a
bag/container for transport back to the lab. Carefully replace rocks in the
riffle.
9. Algal samples can be brought back the lab for processing, examination, and
identification.
Scenario 2. One stream comparison.
1. Identify a single system that has a known point source (e.g., waste water
treatment plant) that releases water into the stream. The stream should be
shallow, wadeable, and have a riffle habitat(s) for students to investigate.
2. Make certain that you have permission from the neighboring land owner(s)
to sample.
3. Enter the sample location downstream from the riffle(s) that you will be
sampling.
4. Work your way to a riffle site DOWNSTREAM of where the water is
dumping in the stream. Visually inspect the rocks for algal specimens.
5. If measurements of water quality are to be done (i.e., pH, specific
conductance), please take samples from the bank before disturbing the site.
6. Large filamentous forms can be collected by hand or with forceps and
placed in a bag/container (with some stream water) for transport back to the
lab.
7. Have students pick five rocks out of the riffle and transport them to the bank
for processing.
8. A known area (e.g., 5 cm x 5 cm) should be scrapped or brushed to loosen
the attached algal mat on each rock. Use stream water to rinse the loose
© 2010, Ohio Northern University: Dr. Debra Gallagher, Dr. Robert Verb, Dr. Ken Reid and Ben McPheron
algae into a bag/container for transport back to the lab. Carefully replace
rocks in the riffle.
9. Move UPSTREAM, past the point where water is being discharged into the
stream, and locate the second riffle habitat.
10.If measurements of water quality are to be done (i.e., pH, specific
conductance), please take samples from the bank before disturbing the site.
11.Large filamentous forms can be collected by hand or with forceps and
placed in a bag/container (with some stream water) for transport back to the
lab.
12.Have students pick five rocks out of the riffle and transport them to the bank
for processing.
13.A known area (e.g., 5 cm x 5 cm) should be scrapped or brushed to loosen
the attached algal mat on each rock. Use stream water to rinse the loose
algae into a bag/container for transport back to the lab. Carefully replace
rocks in the riffle.
14.Algal samples can be brought back the lab for processing, examination, and
identification.
Equipment/Materials:
Hand lenses
Collection containers (ziplock bags, old plastic container with screw top lids)
Pipettes/syringes/basters
Notebooks
Toothbrushes
Forceps
Spoon/Knife
Hanna Combo Meter (temperature, pH, etc.)
Data Sheet-Field Collection
© 2010, Ohio Northern University: Dr. Debra Gallagher, Dr. Robert Verb, Dr. Ken Reid and Ben McPheron
Microscopes
Well slides
Cover slips
Counting chambers
Identification keys
Activity Sheets:
Notebook
Engage:
Show the pictures of air and water pollution (below). Ask students if they think
the air is polluted? What evidence do they have for their answer? Do they think
the water is polluted? What evidence do they have? Sometimes we use
macroinvertebrates to determine the quality of water. Today we are going to use
Algae to help us determine how much organic pollution is in a water sample.
Explore:
SEE TEACHER NOTES-SITE LOCATION
1.
2.
3.
4.
5.
Explain that you will be going to a site to collect water samples.
Review procedures for collecting samples.
Explain to the students that they will sketch the site in detail
Students and teacher go to collections site
Students will take detailed notes about the site and make sketches in their
notebooks. Include information such as:
a. Water temperature
b. Outside temperature
c. Weather
d. pH of water
© 2010, Ohio Northern University: Dr. Debra Gallagher, Dr. Robert Verb, Dr. Ken Reid and Ben McPheron
e. Sketch of the site
6. Students collect samples of water to be taken back to the classroom.
Explain:
Discuss what students will expect to find in the water samples.
Ask the following questions:
“Will your samples indicate little or much organic pollution?”
“What evidence do you have to support you answer?”
Extend:
Laboratory Analyses
Observe each type of macroalgae (filamentous) algae under the compound
microscope. Make observations, measurements, sketches, and records of the
magnification in your laboratory notebook. Use this information and any available
taxonomic keys to indentify the algae. Be certain to record the species name and
where it was collected.
Take samples from your homogenized algal scrapping and place them in your
counting chamber. Place a plastic coverslip on top and examine under the
compound microscope. Make observations, measurements, sketches, and records
of the magnification in your laboratory notebook. Use this information and any
available taxonomic keys to indentify the algae. Be certain to record the species
name and where it was collected. Keep track of how many times you see the algae
and how many different fields of view were used.
Researchers have developed many biologic indices (or metrics) that assist in
determining the health of a body of water. A simple one based on selected algal
genera (Palmer, 1969; Person 1989) is found in the table below.
© 2010, Ohio Northern University: Dr. Debra Gallagher, Dr. Robert Verb, Dr. Ken Reid and Ben McPheron
Genus
Anacystis
Ankistrodesmus
Chlamydomonas
Chlorella
Closterium
Cyclotella
Euglena
Gomphonema
Lepocinclis
Melosira
Index
1
2
4
3
1
1
5
1
1
1
Genus
Micractinium
Navicula
Nitzschia
Oscillatoria
Pandorina
Phacus
Phormidium
Scenedesmus
Stigeoclonium
Synedra
Index
1
3
3
5
1
2
1
4
2
2
If there are five or more cells of a particular genus on a slide, the algae must be
included in the analysis. The index numbers for all of the recorded algae are
totaled. Any algae found that are not listed in the table above have a pollution
factor of zero. See example below:
Sample A:
Genus identified
Ankistrodesmus
Closterium
Synedra
Sprirogyra
Phormidium
Draparnaldia
Euglena
Total
# of cells
5
23
7
15
29
18
6
Pollution index value
2
1
2
0 (not in the index table)
1
0 (not in the index table)
5
11
If the pollution score is 20 or more, the score is indicative of high organic
pollution. A score of 15-19 is evidence of probable or intermediate organic
pollution. Lower score may depict less organic pollution or some other factor is
limiting algal growth.
Make calculations of the pollution score for each of the stream sites that you
visited and sampled. Explain your results.
Evaluate:
Notebook
© 2010, Ohio Northern University: Dr. Debra Gallagher, Dr. Robert Verb, Dr. Ken Reid and Ben McPheron
Teacher Background
Biomonitoring is the assessment of health of a habitat through the examination of
the organisms living there. In the aquatic environment, common bioindicators
include algae, macroinvertebrates, fish, and amphibians. Lowe and Pan (1996)
noted that there are several characters that make algae particularly useful in the
bioassessment or water quality including: 1) Sessile nature (algae are fixed in place
and cannot avoid pollution), 2) Species rich communities (many species in a small
area), 3) Samples are easy to collect and store, and 4) Identification is not difficult
with most taxonomy being based on the shape and color of the organism.
There have been many attempts to create algal indices (species which indicate
different types of pollutants and/or habitat conditions). One early attempt at
linking different algae to various water conditions is Algae in Water Supplies by C.
Mervin Palmer (1962). Other lists of algal indices may be available from
governmental agencies or academic institutions in your area.
© 2010, Ohio Northern University: Dr. Debra Gallagher, Dr. Robert Verb, Dr. Ken Reid and Ben McPheron
Air Pollution
© 2010, Ohio Northern University: Dr. Debra Gallagher, Dr. Robert Verb, Dr. Ken Reid and Ben McPheron
Water Pollution
© 2010, Ohio Northern University: Dr. Debra Gallagher, Dr. Robert Verb, Dr. Ken Reid and Ben McPheron