Investigating water quality through quantative and qualitative analysis of benthic macroinvertebrate sampling.
Summary
In this Biology field lab, students will investigate the relative health of an aquatic system based upon benthic (bottom dwelling) macroinvertebrates (small, but seen with the naked eye, mostly insect larvae), as these are bioindicators of water quality and habitat quality. Students will collect various critters from a pond, lake, ditch, stream or river, and categorize the number of each type in a small sample. From the pooled class data, they will assign relative pollution values and come up with a biodiversity index for that aquatic biome. Students write a lab report describing their results. Students can also develop a comparison between healthy and unhealthy aquatic biomes if 2 different environments (same stream, different areas or 2 different streams) are used.
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Learning Goals
This activity is designed for students to explore the aquatic environment(s) in their community and determine the relative health of it through qualitative and quantitative analysis.
Context for Use
This is a field exercise that will take from 2 to 5 days+ depending on period time, grade level, class size, sampling, and how deep into the lesson the teacher wants to get. Equipment for a class of 24 working in groups of 3 is as follows: 8 dip nets, 8 buckets to obtain samples, 8 ice cube trays (to separate out each type of critter), 8 laminated identification tables with pollution values, and data table. Optional equipment could include field identification guides and magnifying glasses (for deciphering differences in types of critters). Depending on the environment, the students may make an artificial substrate, usually 4 to 6 weeks ahead of time. Students will investigate the relationships of these animals to factors found in the environment (biotic and abiotic).
Description and Teaching Materials
This is a rough estimate. Time can be shortened or lengthened depending on student activities or lecture time.
Day 1
Introduction to benthic macroinvertebrates, how to get samples and where to get them.
Day 2
Get out and get samples. (store in a cool environment like a fridge)
Day 3
Classify organisms using table, dichotomous key, or field guide.
Day 4
Compile classroom data, assign pollution values and come up with biological index.
Day 5
Student reflection, assessment.
Day 1
Introduction to benthic macroinvertebrates, how to get samples and where to get them.
Day 2
Get out and get samples. (store in a cool environment like a fridge)
Day 3
Classify organisms using table, dichotomous key, or field guide.
Day 4
Compile classroom data, assign pollution values and come up with biological index.
Day 5
Student reflection, assessment.
Teaching Notes and Tips
Students should have some understanding of how these critters in the environment are able to exist and what factors lead to them being able to live there. Example: Leaches can inhabit virtually any type of water because they have a high pollution tolerance, whereas a stone fly larvae is very sensitive to any pollution and will not inhabit water that has a low dissolved oxygen content from pollution or runoff. Each has a certain niche that it can thrive in. Each species is assigned a pollution value (PV on the handouts). Those with a high value (7—9) are pollution tolerant, those with a low value (1—3) have little tolerance. The calculations are made as follows...
PV x Density (how many of each) / total density (total number of organisms collected) = biodiversity index
The lower the number the better.
This activity looks at the bioindicators of water quality rather than the chemistry involved in water quality. It gives the students a unique insight into the effects of the pollutants and environment makeup and past the analysis of pollutants and DO in water. It requires very little in the case of probes, electronics and testing equipment, which makes it much more suitable for larger classes and schools with minimal budgets.
PV x Density (how many of each) / total density (total number of organisms collected) = biodiversity index
The lower the number the better.
This activity looks at the bioindicators of water quality rather than the chemistry involved in water quality. It gives the students a unique insight into the effects of the pollutants and environment makeup and past the analysis of pollutants and DO in water. It requires very little in the case of probes, electronics and testing equipment, which makes it much more suitable for larger classes and schools with minimal budgets.
Assessment
Students will summarize their data in a class data table with the relative biological index. A comparison can be made to another type of aquatic environment if 2 samples are used. A conclusion (essay or paper) that states the factors (variables) or locations that influence population levels and diversity (DO, temp, substrate, invasive species, or human activities, etc. are some of the variables). Also the interactions of those variables from the physical and biological environment (why and how they exist or coexist).
Standards
Grades 7. IV. Life science. C. Interdependece of life. 3. ecosystems and populations. & 4. factors that influence life
Grades 9 - 12. IV. Life science. C. Interdependence of life. 1. Variables that influnce populations & 4. changes related to population and biodiversity.
Grades 9 - 12. IV. Life science. C. Interdependence of life. 1. Variables that influnce populations & 4. changes related to population and biodiversity.