Healthy Waters
Summary
Animals are often more finely-tuned than humans to changes in an environment. At one time, coal miners used canaries to detect the presence of dangerous gases because these birds are sensitive to shifts in air quality. Similarly, aquatic macroinvertebrates have different tolerances to water pollution. The health of a stream can be judged by the macroinvertebrate species that are present and may indicate shifts in an environment before such changes are easily recognizable to humans.
Both macroinvertebrate species that are sensitive to and those tolerant of pollution can live in a stream with good water quality. With increased pollution however, fewer sensitive species will be found. If the stream's water quality is very poor, only those macroinvertebrates tolerant of pollution will survive. EPT is an abbreviation for Ephemeroptera, Plecoptera, and Trichoptera (mayflies, stoneflies, and caddisflies), insect groups that are largely intolerant of pollution. If many EPTs are present, the water quality is probably good. Macroinvertebrates capable of surviving in very polluted water include aquatic worms, leeches, and midge larvae.
The Hilsenhoff Biotic Index, or HBI, measures the health of a stream by assigning tolerance values to macroinvertebrates which range from 0 for organisms that are very sensitive to organic wastes to 10 for organisms that are very tolerant of organic wastes. The biotic index of a stream site is found by collecting a sample of benthic macroinvertebrates, then multiplying the number of individuals within each separate species by the tolerance value of the species. The resulting products are then added together and this sum is divided by the total number of organisms in the sample.
*taken from "Windows into wonderland-mystery into the missing bugs" lesson from Yellowstone National Park
Learning Goals
- Calculate the Biotic Index of each site.
- Analyze the "water quality" of their sample with 100% accuracy.
- Comparatively determine the sample site that indicates high pollution.
Concepts: By the end of this lesson, students should understand how we can use macroinvertebrates to determine the quality of water in a river/stream.
By the end of this lesson, students should be able to determine how a community can increase or decrease the water quality of its local steams/rivers through its practices (runoff, fertilizers, pollution, etc)
Vocab: Biotic indicators, Biotic Index, macroinvertebrate, pollution tolerance, benthic, Ephemeroptera, Plecoptera, and Trichoptera
Context for Use
Estimated time - (2) 45 minute class periods
Equipment - (if using lab from website)
Large bag of M&Ms
Bag of macaroni noodles
Box of Cheerios
Bag of beans
Small plastic bags
Paper
Pencils
Equipment - (if using modified lesson)
10 ice cube trays
Tweezers
stereoscopes
Transparencies (cut out each species of macroinvertebrates)
Ziploc baggies (to put "samples" in from each stream)
Pencil
Paper
I am using this activity in the very beginning of the year to introduce my insect collection. I want to do more ecology in my class and have it as a recurring theme throughout the year. I believe this lesson can be adapted to high school (actually going out and collecting the macroinvertebrates and then calculating). Could also be used in an elementary setting.
Description and Teaching Materials
We will discuss these questions and make a concept map on the board from these questions/answers. We will then talk about water and ecology in a lecture/ Q & A format. The lab will be explained after the lecture and students will start the investigation. The closure for the activity will be to post all the results on an overhead and then discuss why each stream is different and what the difference means to us.
Equipment - (if using lab from website)
Large bag of M&Ms
Bag of macaroni noodles
Box of Cheerios
Bag of beans
Small plastic bags
Paper
Pencils
Equipment - (if using modified lesson)
10 ice cube trays
Tweezers
stereoscopes
Transparencies (cut out each species of macroinvertebrates)
Guide to macroinvertebrates
Ziploc baggies (to put "samples" in from each stream)
Pencil
Paper
Reference: Windows Into Wonderland - Mystery of the Missing Bugs (Windows Into Wonderland website no longer available)
Biotic index lesson plan (modified) (Microsoft Word 33kB Aug24 07) Data Table Macroinvertebrates (modified) (Microsoft Word 65kB Aug24 07) Data table macroinvertebrates (yellowstone version) (Acrobat (PDF) 19kB Aug24 07) Rubric (yellowstone version) (Acrobat (PDF) 41kB Aug24 07)
Teaching Notes and Tips
Assessment
Formal assessment for this lab would be done with the data table worksheet and the questions included on it. Also, if doing the Yellowstone version, you can use the supplied rubric.
Standards
B.4 - dichotomous keys
B.5 - kingdom
C.1 - irreversible effects by humans
C.2 - population definition
C.3 - ecosystem
C.4 - factor that effect #'s in an ecosystem
D.5 - reproduction
E.3 - adaptations to enhance reproduction