BACKGROUND INFORMATION:
Tree species maple, beech, black cherry and birch cover much of the remaining forested areas of Pennsylvania. Black cherry is currently one of the main "cash crops" coming out of Allegheny National Forest (our closest national forest). These trees are deciduous. This means that they drop their leaves every year. Streams that have a canopy cover receive these leaves, which become food for aquatic invertebrates.
A healthy stream has a balance between how much leaf litter enters the stream and how much is consumed by the invertebrate. Any unconsumed leaf litter affects the amount of dissolved oxygen in the stream water. This affects what can live in the stream: invertebrates, crustaceans, mollusks and fish. This also affects the food chain of mammals and birds. A "healthy" stream generally indicates that the surrounding riparian habitat is also "healthy".
Part of every species definition is a limit or tolerance level for various environmental factors: biological, chemical and physical. These factors set the guidelines for habitats, places where certain species tend to live, and can be reduced to a numerical value between 1 and 10. If we try to determine a food preference in aquatic invertebrates, we could possibly predict the future invertebrate diversity and stream health by a survey of the canopy species.
CONCEPTS:
Do aquatic invertebrates exhibit food preferences?
Is the presence of certain aquatic invertebrates indicative of stream health?
GOALS:
Students will demonstrate the use of kicknets, invertebrate keys, CBL systems and probes (as listed in equipment) and HACH kits to discover correlations in food preferences of invertebrates, and assess stream health.
EQUIPMENT:
PROCEDURE:
Collect the leafpacks and place one in each ziplock bag. The student should label the bag number and microhabitat with the marker.
Have the students use the above equipment to record:
Temperature
pH
Dissolved oxygen
Iron, Nitrates and Phosphates as per kit instructions.
Have the students record the information on the worksheets.
Have 5 groups of students kicknet in different areas of the stream.
Return to lab to sort and identify the invertebrates, using the Cummins guide.
Once the invertebrates have been identified the students should take
a slip of paper and write, in pencil, the stream name and
collection date on one side and the Family and Order of the invertebrate
on the other side.
Place the slip of paper and the identified invertebrate in a small glass vial filled with alcohol. Seal the vial.
Keep a running tally of invertebrates you identified on your Biotic Index Worksheet.
Continue until all specimens are identified.
Calculate the Biotic Index for the stream.
The total number of each type is written in column B and the sum of the column is written at the bottom.
Multiply column A by column
B to get the total tolerance value for column C. Record value.
Sum the total
tolerance values of column C and write at the bottom.
Divide B into C (C/B) and write on the worksheet.
Once the kicknet sample has been completed, assign each group 3 leafpacks of the same mixture.
Repeat steps 5 10 for the leafpacks. Share the data you collect with the other groups.
Begin lab report.
Lab Report:
Bar graphs will be constructed based on the number of life forms found in the leafpacks from the 3 different stream sites. Five pages of graphs will be submitted on graph paper. Each page will contain 3 bar graphs for one leafpack, one graph for each site. The life forms will be grouped into 3 orders listed on the x-axis and the number found listed on the y-axis. A summary page comparing the graphs will be included in the lab report.
Closing Questions:
Was our sample size large enough? If you would add,
how many more would you add?
Do you think there was a correlation between the
biotic index of the stream and the riparian habitat?
How could we quantify this?
If there was anything you would do differently if
you did this experiment over?
Summary Kick Net Data Sheet
Date Collected _____________________________
Class ______________________________________ Stream _______________________
Experimental Condition _____________________________________________________
| ü | Taxon |
|
| Ephemeroptera (Mayflies) | ||
| Odonata | ||
| Anisoptera (Dragonflies) | ||
| Zygoptera (Damselflies) | ||
| Plecoptera (Stoneflies) | ||
| Megaloptera | ||
| Dobsonflies | ||
| Alderflies | ||
| Coleoptera (Water Beetles) | ||
| Beetle larvae | ||
| Adult beetles | ||
| Water Pennies | ||
| Trichoptera (Caddisflies) | ||
| Diptera (True Flies) | ||
| Chironomidae (Midges) | ||
| Simuliidae (Black Flies) | ||
| Tipulidae (Crane Flies) | ||
| Tubellaria (Planarians) | ||
| Oligochaeta (Earthworms) | ||
| Hirudinea (Leeches) | ||
| Gastropoda (Snails) | ||
| Isopoda (Sowbugs) | ||
| Amphipoda (Scuds) | ||
| Miscellaneous Macroinvertebrates |
Total # of Different Types _____
Total # of Macroinvertebrates _____
Summary Leaf Pack Data Sheet
Date Collected _____________________________ Leaf Species __________________
Class ______________________________________ Stream _______________________
Experimental Condition _____________________________________________________
| ü | Taxon |
|
| Ephemeroptera (Mayflies) | ||
| Odonata | ||
| Anisoptera (Dragonflies) | ||
| Zygoptera (Damselflies) | ||
| Plecoptera (Stoneflies) | ||
| Megaloptera | ||
| Dobsonflies | ||
| Alderflies | ||
| Coleoptera (Water Beetles) | ||
| Beetle larvae | ||
| Adult beetles | ||
| Water Pennies | ||
| Trichoptera (Caddisflies) | ||
| Diptera (True Flies) | ||
| Chironomidae (Midges) | ||
| Simuliidae (Black Flies) | ||
| Tipulidae (Crane Flies) | ||
| Tubellaria (Planarians) | ||
| Oligochaeta (Earthworms) | ||
| Hirudinea (Leeches) | ||
| Gastropoda (Snails) | ||
| Isopoda (Sowbugs) | ||
| Amphipoda (Scuds) | ||
| Miscellaneous Macroinvertebrates |
Total # of Different Types _____
Total # of Macroinvertebrates ________
Biotic Index Worksheet
Team ________________________________ Stream _________________________
Experimental Condition ___________________________________________________
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X |
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C | |||
| Taxon |
Tolerance Value |
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Tolerance Value |
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| Ephemeroptera (Mayflies) |
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| Anisoptera (Dragonflies) |
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| Zygoptera (Damselflies) |
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| Plecoptera (Stoneflies) |
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| Megaloptera (Dobsonflies & Alderflies) |
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| Coleoptera (Water Beetles) |
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| Trichoptera (Caddisflies) |
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| Diptera (True Flies) | |||||||
| Chironomidae (Midges) |
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| Simuliidae (Black Flies) |
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| Tipulidae (Crane Flies) |
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| Tubellaria (Planarians) |
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| Oligochaeta (Earthworms) |
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| Hirudinea (Leeches) |
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| Gastropoda (Snails) |
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| Isopoda (Sowbugs) |
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| Amphipoda (Scuds) |
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Sum of Total Tolerance Values / Sum of Abundance = Biotic Index
_____ / _____ =
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TEACHERS NOTES:
This lesson would be good follow-up to an introductory invertebrate identification lab.
To Prepare Leaf Packs
You will need 15 onion bags, 15 bricks, 15 numbered plastic pigeon bands and leaves to make 15 leaf packs.
Keep the mass of the leaves in the leaf packs consistent and do mixtures as a % by weight, as illustrated by the following column.
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| 3 | 100% | ||
| 3 | 100% | ||
| 3 | 100% | ||
| 3 | 34% | 33% | 33% |
| 3 | 40% | 20% | 40% |
Place the leaf packs at least 3 weeks prior to the
lab date. Place one of each leaf mixture at three different microhabitats:
riffle, glide and pool.
Print the worksheets on waterproof paper.
This lesson has been designed for 5 groups of 4 students.
This lesson is an all day event. Caution students to wear old clothes and sneakers and to bring sunscreen, bug spray and waders if they have them.
Using a Kicknet
Select a fast-moving area of the stream: 3-12 inches deep, with stones 2-10 inches or larger, and low silt levels. (This is an ideal habitat for aquatic invertebrates.)
Three people position the kicknet downstream of a riffle, making sure the bottom edge fits tightly across the streambed.
Start a meter above the net and churn up the bottom of the streambed, kicking towards the net. Do this for several minutes.
Pick up any large stones and search the surface for invertebrates (such as caddisflies). Place them in the net.
Remove the net with a forward swooping motion. Try not to allow any organisms to escape from the net.
Place the sieve underneath one end of the net and use a squirt bottle at the opposite end to flush the debris down into the sieve.
Clean the sieve out and place all contents into a bottle of alcohol.
Label the bottle with the day and location that you collected the sample.
ADAPTATIONS FOR SPECIAL NEEDS STUDENTS
Prior to lesson: Stream and ecology videos that relate to the area to be studied. Good reference books would be helpful; especially those of a lower reading level such as middle school. They tend to have larger print and more colorful pictures.
During the lesson: At the stream, pair the ESL student with mature, responsible students who are willing to help the student become a real member of the team.
After the lesson: The student can organize the collected data. The student will be ready to see the sequence to some of the material and processes. The mathematical results should help them match some English words to the concepts.
Prior to lesson: The strategy would be quite similar to the student who has English as a second language. Depending on the reading level and the interests of the student, individual references should be sought. The librarian should be able to help the student and the teacher to obtain the appropriate references.
During the lesson: Slow learners will be less intimidated by the scientific processes if they feel that they have help. They should be incorporated into a team that has previously displayed skill, responsibility and maturity.
After the lesson: The slow reader could be a good oral presenter. If that is the case, this might be the group obligation that they could fulfill. The ability to collect data should not be affected by a lower reading ability. This person could be the best recorder and sketch artist for field organisms that are collected.
During the lesson: The student should be granted as little "off-time" as possible. One method to keep this student busy at all times would be to assign him or her the task of archivist or field librarian. They would be photographing the groups performing the tasks and videotaping the site, the procedures and the organisms collected.
After the lesson: If there is a need and time for this, an oral presentation using the video and pictures processed would provide a good experience for this student and a good review for the class.
RUBRIC:
Two instruments, Invertebrate Identification and the Lab Report will grade this lesson. Invertebrate Identification will be worth 25 points and the Lab Report will be worth 15 points. The grade will be the sum of the two.
Are the invertebrates correctly identified as to Order and Family? 25 points
Teacher randomly checks bottles of invertebrates.
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| 100 90% | Correct to Family | 25 |
| 89 80% | Correct to Family | 24 |
| 79 70% | Correct to Family | 23 |
| 69 60% and 100 90% | Correct to Family and Correct to Order | 22 |
| 59 50% and 100 90% | Correct to Family and Correct to Order | 21 |
| 49 40% and 100 90% | Correct to Family and Correct to Order | 20 |
| 39 30% and 100 90% | Correct to Family and Correct to Order | 19 |
| 29 20% and 100 90% | Correct to Family and Correct to Order | 18 |
| 19 10% and 100 90% | Correct to Family and Correct to Order | 17 |
| 89 80% | Correct to Order | 16 |
| 79 70% | Correct to Order | 15 |
| 69 60% | Correct to Order | 14 |
| 59 50% | Correct to Order | 13 |
| 49 40% | Correct to Order | 12 |
| 39 30% | Correct to Order | 11 |
| 29 20% | Correct to Order | 10 |
| 19 1% | Correct to Order | 9 |
| None identified | 0 |
Lab Report: 15 points are earned by the following:
Introduction: 3 points. Two or three sentences in a general statement including applications mentioned in class.
Purpose statement: 3 points. The correct concept must be stated in clear concise language that is grammatically correct.
Summarized Procedure: 3 points for a complete summary. 2 points for missing one critical concept. 1 point for missing a concept or concepts and grammatical and/or spelling errors.
Calculations and Observations: 3 points for showing all bar graphs. 2 points for showing the majority of the bar graphs. 1 point for turning in 2/5th of the bar graphs. 0 points for turning in a report with one or fewer bar graphs.
Conclusion: 3 points for verifying if the data supports the tested theory, how to improve accuracy and precision in the experiment and explaining where errors were made in their calculations or procedure. 2 points for leaving out one of the above. 1 point for leaving out two of above. Zero points for leaving out all of the above.
EXTENSIONS:
For gifted students you could:
Assign an oral presentation at a science fair.
Have the students categorize the invertebrates by functional groups (predators, shredders, etc).
To see how much biomass was consumed have the students separate and save the leaves from the leaf packs. They can be rinsed, cleaned, dried in an oven then massed.
Try to determine if the decomposition of one species of leaf has a more of a detrimental effect on D.O.s. Set up four aerated aquariums. Label the aquariums A, B, C, and D. Leave aquarium A empty as a control. Sort the leaves by species, weigh for equal mass and place maple leaves in aquarium B, birch leaves in aquarium C and beech leaves in aquarium D. Check the dissolved oxygen levels once a week over a period of three months to check for differences.
Pulverize the leaves in a solvent and run in a TLC to examine for any
natural insect repelling properties. Black cherry is an excellent leaf
to use for this experiment because it contains cyanide.
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