Biological Assessment of Stream Quality
Mary V. Ball
Jefferson City, Tennessee 37760
Mary Ball teaches non-majors biology classes, genetics, ecology, and embryology in the Biology Department of Carson-Newman College. Her interests include science education, environmental education, and stream monitoring.
© 1991 Carson-Newman College
[ABLE's Copyright Policy]
|Reprinted from: Ball, M.V. 1991.
Biological assessment of stream quality. Pages 75-88, in Tested
studies for laboratory teaching. Volume 12. (C. A. Goldman, Editor). Proceedings
of the 12th Workshop/Conference of the Association for Biology Laboratory
Education (ABLE), 218
Although the laboratory exercises in ABLE proceedings volumes have been tested and due consideration has been given to safety, individuals performing these exercises must assume all responsibilities for risk. The Association for Biology Laboratory Education (ABLE) disclaims any liability with regards to safety in connection with the use of the exercises in its proceedings volumes.
Abstract: By surveying the kinds, density, and abundance of aquatic
invertebrates in a stream it may be possible to assess the quality of the
environmental circumstances. Observations on the stream site and the watershed
may allow identification of environmentally damaging practices or conditions.
Using a variety of simple equipment, which can be made inexpensively or
purchased, students can easily learn the technique of biological assessment
of stream quality. The approach lends itself to being used with non-majors
and majors classes and for independent student research.
The Save Our Streams (SOS) program was originally developed in the 1960s in Maryland by Malcom King, who realized that clean streams were vital to the welfare of Chesapeake Bay. although study of the Bay itself may require a boat and expensive equipment, every school and camp in Maryland is within 1/2 mile of a stream. Since the most serious threat to America's surface waters is "non-point source pollution" (see Appendix A), the Izaak Walton League's SOS Program stresses educating people about how our everyday practices affect water quality by influencing what is carried into streams and waterways by stormwater runoff.
In summary, there are three major reasons to focus on stream quality:
Notes for the Instructor
The Student Outline that follows is an exercise we use in a 3-semester-hour spring course in Environmental Science designed to meet the General Education requirements. We currently schedule nine (9) 2-hour laboratory sections per week, with 2530 students per laboratory. Each section is staffed by one course instructor and one undergraduate Teaching Assistant.
We "rig" the water samples to simulate conditions listed in Table 5.3. We collect aquatic insects from local streams and preserve them in 70% ethanol for student "sorting." Having samples of live organisms promotes interest, but is not always possible.
In some of our other courses, with a longer lab period and fewer students, we have the students collect water samples and benthic macroinvertebrates. Ideally, they should be able to visit at least one "good" site before studying polluted sites.
The techniques described in Appendices B and C lend themselves for use in Honors projects and independent student research. For campuses located on or near streams, Adopt-A-Stream programs offer a way to involve students in meaningful long-term collection of data.
This exercise was developed primarily using SOS materials from The Izaak Walton League of America (IWLA). We began looking for resources because we were distressed at the inadequate coverage of aquatic ecology in the course textbook and wanted to supplement it. As we examined the SOS materials, we realized that the empowerment they offer students is as important as the content.
Table 5.3 is from the SOS's A Stream Watcher's Guide. Table 5.7 is from Richard Klein's three guides: Hands-on Streams and Rivers, Preservation and Enhancement of Stream Quality, and Stream Quality Assessments. All of these guides can be obtained from: The Izaak Walton League of America, Inc., 1401 Wilson Blvd., Level B, Arlington, VA 22209. Resource materials are described in Appendix D: print materials on benthic macroinvertebrates and collection techniques, sources for audiovisual materials, and information on monitoring equipment.
"Save Our Streams"
[Slogan of the Izaak Walton League of America]
Having completed the exercise, you should be able to:
Major Causes of Concern in Regard to Stream Quality
The presence of excessive amounts of soil in water can smother aquatic life, clog fish gills, and cut off light to underwater plants. Two major causes of sediment pollution are the uptake of exposed soil by rainwater and the eroding of stream banks by an excessive volume of runoff.
Excessive volume of runoff results from lack of absorption of rain into the ground and may negatively affect aquatic life in two different ways. During dry weather, stream levels tend to be lower due to lack of underground water, but, during rainy periods, aquatic organisms are exposed to flow rates that may scour the stream bed.
Decomposition of excessive amounts of organic substances by microbes uses oxygen and may reduce oxygen levels to the point that other aquatic organisms suffocate. The major causes of oxygen depletion are "organic enrichment" and the addition of plant nutrients to the water. Organic enrichment refers to the introduction into the stream of organic material. Sources of organic material are listed in Table 5.1.
Table 5.1. Sources of organic material in streams.
|Source||Example of organic materials present|
|Sewage treatment plants
Septic system failure
Ground-up food scraps
Food waste, leaves, grass clippings
Pet feces, grass clippings
Introduction of plant nutrients can cause excessive growth of algae, whose eventual decomposition can also contribute to oxygen depletion. The nutrients may be a by-product of decomposition of organic materials, or may be the result of fertilizers in runoff or of phosphates in detergents.
The most common toxic substances are listed in Table 5.2.
Table 5.2. Common toxic substances.
Release of "treated" water
Runoff, "do-it yourself" oil-changing
(motor oil, gasoline, kerosene, etc.)
Salting of roads
Problems in this category could include channelization, damming, addition or removal of bed material, removal of water, or changing water temperatures.
A: Mapping the Watershed of a Stream
B: Physical Assessment of Stream Quality
|Muddy water||Erosion of soil in upstream areas; in tidal waters it could also be caused by high winds.|
|Green color||Microscopic plant cells called algae. Algae growth may be caused to exceed normal limits due to excessive water. Nutrient sources include: fertilizers, pet waste, grass clippings, leaves, etc.|
|Yellow-brown to dark brown||Acids released from decaying plants. Naturally occurs each fall when dead leaves collect in the stream. Also common in streams draining marsh, or swampland.|
|Orange to red coating on bed||Results from bacterial action upon iron. May indicate a high erosion rate or industrial pollution.|
|Colored sheen on surface||May indicate oil has entered the stream, particularly if there is also an oily odor.|
|Foam||When foaming occurs in only a few scattered patches and is less than 3 inches high and cream-colored it is probably natural. If the foaming is extensive, white in color, or greater than 3 inches, it may be due to detergents entering the stream.|
|Rotten egg color||Indicates sewage pollution. Odor may also be present in marsh or swampland.|
|Yellowish coating on bed||May indicate polluted water draining from a coal mine.|
|Musky odor||May indicate presence of untreated sewage, livestock waste, algae, or other conditions.|
|White cottony mass||Could be "sewage fungus." The presence of this growth indicates sewage or other organic pollution.|
|Blue-green algae (Cyanobacteria)||Could indicate sewage or other pollution if growth is excessive.|
Table 5.4. Possible causes of unusual color or odor of water samples.
|Sample||Possible causes of unusual condition|
C: Biological Assessment of Stream Quality
One measure of stream quality is the diversity, abundance, and kinds of organisms present (see Table 5.5). Although any group of organisms might be surveyed, a survey of aquatic insects has several advantages.
Aquatic insects may be collected from a stream site in several ways. A simple way is to hold an old window screen against the bottom while someone kicks up the bottom just upstream, allowing the dislodged insects to be caught on the screen. Another way is to place a Hester-Dendy sampler, a stack of fiberboard plates, into the stream for 6 weeks or longer. Insects that attach to the "insect condo" can then be sampled.
Insect identification can be difficult, but the Izaak Walton League has developed an insect identification card to assist in the process. Once the "catch" is identified, the results can be interpreted.
Table 5.5. Relationship of water quality and diversity, abundance, and kinds of organisms.
|Expected results of insect survey|
|Polluted*||Pollution-tolerant types only, little variety|
|Excellent||Species that require high water quality, diverse|
* If only one or a few kinds or organisms are present but are in great abundance,
organic enrichment. If no insects are present, or a few of several kinds, suspect toxic pollution.
Table 5.6. Number of aquatic insects in stream sample.
|___ caddisfly larvae
___ dobsonfly larvae
___ mayfly larvae
___ stonefly larvae
|___ beetle larvae
___ crane flies
|___ blackfly larvae
___ midge larvae
Table 5.7 shows the effects of various land uses and activities. Table 5.8 describes harmful practices. Refer to these tables, as required, to answer the following questions:
Table 5.7. Potential pollutant quantities delivered to streams from various land uses and activities.
|Natural, undisturbed forestland||low||low||low||none||low||low|
|Construction sites||very high||low-mod||mod-high||mod-high||mod||high|
|Surface mines: Coal||very high||low-mod||low-mod||low-mod||high||high|
|Surface mines: Sand and gravel||high||low-mod||low-mod||low-mod||mod||high|
* Runoff quantity
Table 5.8. Potentially polluting practices.
|Pouring oil drained from cars onto a street or into a gutter.||When oil enters stream it can kill aquatic life.||Take oil to a service station. Most managers will allow customers to pour used oil into the station's storage tank.|
|Dumping grass clippings or leaves into a stream or gutter.||When leaves or grass enter water they will decay and use oxygen.||Either material may be composted or bagged and put out with the trash. Leaves could be mulched by running a mower over the lawn with the vent closed. Grass may be left on the lawn or raked up only after every third cutting.|
|Fertilizing the lawn.||Fertilizers, when washed into a body of water, can cause algae to grow too much.||Most lawns need only nitrogen. This eliminates the need for stronger phosphorous fertilizers that encourage algae. Direction on fertilizer bags should be followed.|
|Spraying pesticides about the home and garden.||Pesticides can kill fish and other life when washed into our waters.||Maintaining a healthy lawn with proper cutting and careful fertilizing is the best way to prevent weeds. Bugs that attack garden plants can usually be washed off with a hose or picked off by hand.|
|Allowing pets to run free.||The manure pets deposit on the ground can spread disease or use oxygen when washed into our waters.||Pets should be kept within a fence or on leash. A thoughtful person would collect his/her pet's waste.|
Algae: Simple plants which do not grow true roots, stems, or leaves and live mainly in water, providing food for the food chain.
Biological assessment: Assessing water quality by determining the diversity, abundance, and kinds of organisms that inhabit the stream.
Chemical assessment: Assessing water quality by performing various chemical tests to characterize the chemical composition of the water.
Culvert: A closed passageway (such as a pipe) under roadways and embankments which drains surface water.
Dump: A land site where trash is left exposed in a way which does not protect the environment.
Effluent: An out-flowing branch of a main stream or lake; waste material (i.e., liquid industrial refuse, sewage) discharged into the environment.
Erosion: The wearing away of land by wind or water.
Floodplain: A low area of land, surrounding streams or rivers, which holds the overflow of water during a flood.
Flow: The direction of movement of a stream or river.
Groundwater: A supply of freshwater under the earth's surface which forms a natural reservoir.
Leaching: The process where materials in the soil (such as nutrients and pesticide chemicals) are washed into lower layers of soil or are dissolved and carried away by water.
Monitoring: To watch and care for a stream on a regular basis.
Non-point source pollution: A type of pollution whose source is not readily identifiable, such as pollution caused by car exhaust carried off city streets as rainwater.
Nutrient: Substance which is necessary for growth of all living things (i.e., oxygen, nitrogen, and carbon).
Pesticide: A chemical that kills insects and rodents.
Physical assessment: Assessing water quality by the appearance and/or odor of a sample.
Point source pollution: A type of pollution that can be tracked down to an easily noticeable cause, such as discharge pipes and people putting chemicals and trash into water.
Pollutant: Something that makes land, water, and air dirty and unhealthy.
Pollution: The presence of waste that makes the world around us dirty and contaminated.
Pond-riffle: In a stream or river, areas of deep slow-moving water (pools) or areas of shallow fast-moving water.
Riffle: A shallow area of water with a fast current.
Runoff: Water, including rain and snow, which is not absorbed into the ground, instead it flows across the land and eventually runs into streams and rivers; runoff can pick up pollutants from the air and land, carrying them into the stream.
Sediment: Soil, sand, and materials washed from land into waterways.
Sedimentation: When soil particles (sediment) settle to the bottom of a waterway.
Slumping: Sections of soil with or without vegetation that have come loose and slipped into the stream.
Stagnation: When there is little water movement and pollutants are trapped in the same area for a long period of time.
Toxic Substance: Poisonous matter (either chemical or natural, which causes sickness, disease, and/or death to plants or animals).
Undercutting: A type of erosion which occurs when fine soils are swept away by the action of the stream, especially around curves; the result is an unstable overhang.
Watershed: All the land that serves as a drainage for a specific stream or river.
Watertable: The upper level of groundwater.
Waterway: A natural or man-made place for water to run through (such as a river, stream, creek, or channel).
Wetland: An area of land that is regularly wet or flooded, such as a marsh or swamp
Using a D-Frame Net (After Mitchell and Stapp, 1988)
Note: This method has the advantage of being potentially a one-person job, and is recommended for muddy-bottom streams.
Using a Kick-seine (After IWLA SOS materials)
Note: This method works best when three persons team together.
Using a Surber Stream-bottom Sampler (After Brewer and McCann, 1982)
Note: This method uses one person in the stream and two or more on the bank.
Sequential Comparison Index (After Brewer and McCann, 1982)
Note: This method was developed by J. Cairns in 1968 for use by non-biologists doing stream-pollution studies and is rather subjective. Mitchell and Stapp (1988) recommend sampling from all substrate types at a site, including mud and aquatic plants, when this evaluation method is to be used.
Subjective Index of Water Quality
(Adapted from the materials from the Tennessee Scenic Rivers Association)
Note: This method depends only on the number, color, and variety of organisms present and does not require identification of species.
|Water Quality||Number of kinds
|Good||6 or more||More than 30% are tan, brown, black, or green|
|Fair||3 to 6||11 to 30% are tan, brown, black, or green|
|Poor||1 or 2||90% or more are red, white, or gray|
Print Materials on Benthic Macroinvertebrates and Collection Techniques
Brewer, R. and McCann. 1982. Lab and field manual of
ecology. Holt, Rinehart, and Winston, NY.
[This manual explains calculation of the Sequential Comparison Index, use of a Surber stream-bottom sampler, and construction of a home-made Hester-Dendy sampler.]
Caduto, M.J. 1985. Pond and brook: A guide to nature study in freshwater environments. Prentice-Hall, Englewood Cliffs, NJ. [According to the Preface, this book "takes a holistic-ecological view of the complex world of freshwater life." After building a conceptual framework in the first two chapters, each succeeding chapter concludes with a section titled "Explorations and Activities" which describes simple techniques for studying freshwater environments. Chapter 5 has a good description of stream insects and the environmental conditions they experience.]
Klein, R. Three guides: Hands-on Streams and Rivers (31 pages), Preservation and Enhancement of Stream Quality (34 pages), and Stream Quality Assessments (23 pages). [Available from: The Izaak Walton League of America, Inc., 1401 Wilson Blvd., Level B, Arlington, VA 22209. For current prices ask for the Save Our Streams publication list.]
Mitchell, M.K., and W.B. Stapp. 1988. Field manual
for water quality monitoring: An environmental education program for schools.
Thirds Edition. Thomson-Shore, Dexter, MI.
[This manual describes the monitoring procedures used in the 1987 Interactive Rouge River Water Quality Project, in which 32 high schools and middle schools in Michigan, linked by a computer network, used nine physical-chemical tests to calculate an Index of Water Quality at their assigned sites. For persons interested in biological monitoring, Chapter 4 provides a 43-page comprehensive introduction to "benthic macroinvertebrates" and the major environmental factors which affect them. Available from: William B. Stapp, 2050 Delaware, Ann Arbor, MI 48130.]
Sources for Audiovisual Materials
Educational Images, Ltd., P.O. Box 3456, West Side, Elmira, NY 14905
[The 1990 catalog lists several slide sets on aquatic ecology and aquatic invertebrates.]
The Izaak Walton League of America, 1401 Wilson Blvd,. Level B, Arlington,
[A 28-minute video on the Save Our Streams program is available on loan from local IWLA chapters, or for $15.00 from the national office.]
Information on Monitoring Equipment
Accent! Science, P.O. Box 1444, Saginaw, MI 48605.
[Ask for the Field Biology Catalog, which lists Hester-Dendy samplers, and D-Frame nets.]
Brewer and McCann (1982). [See citation above.]
The Izaak Walton League of America. [See address above. The IWLA is a source for custom-made kick- seines and for instructions on home-made kick-seines and D-Frame nets.]
All contents copyright © 1997. Association for Biology Laboratory Education. All rights reserved.