Aquatic Insects

Lesson Plan by Debolina Dutta

Water Quality Index & Diversity Index

General Information

Location: and local creek or stream

Duration:  Approx. 8 class periods, however if time is limited, indicated portions of the lesson may be skipped 

Grade Level:  6th to 12th
Aligned with the California State Standards under the grades nine through twelve biology/life science section on ecology.

Objectives

  1. Academic: To learn about the adaptations, niches, and the life cycles of the common stream insects. Find the water quality index and diversity index of creeks or streams.
  2. Personal: Explore creeks and streams, learn to see the vast diversity of organisms within a stream.
  3. Social: Working collaboratively with other students as a “research team.”

Lesson Development

This series of lessons expose students to the microcosmos of aquatic insects and the diversity they have in a small area of stream or creek. Students are allowed to feel comfortable being near or in creeks and touching insects. Organism memorization and concepts building can be taken further by ingraining these ideas into students’ memory via hands on education. Finally, students will understand the incredible importance aquatic insects have in identifying the water quality of a stream. This understanding can empower students to be mindful of their nearby waterbodies and/or take an active role in preserving their creeks and streams.

Preparation

Everyday:
Photocopy one set Common Macroinvertebrates flash cards (see Appendix 6). I recommend laminating them so you can use them repeatedly and water will not damage them.

Virtual creeks for Day Two:
Photocopy paper insects from Appendix 3 to form several virtual creeks (one for each group). Make different creeks that have either:

  • high biodiversity & high water quality index
  • high biodiversity & low water quality index
  • low biodiversity & high water quality index 
  • low biodiversity & low water quality index

Day Three:

  • Photocopy or write on the board the methods and formulas for calculating water quality index and diversity index. Use Appendices 1 and 2.

Day Four and Five

  • Photocopy Leader’s Aquatic Insect Datasheet (see Appendix 4) and students’ Aquatic Insect Datasheet (see Appendix 5).

Background Information

While it is not required, students should have a general understanding of the importance and interdependence of organisms and their habitat.

Vocabulary

Adaptation: the ability to change, either physically or behaviorally, to better survive environmental conditions

Biodiversity: measurement of the healthiness of a habitat; measured by the number of different species (richness) and by their distribution. A healthy environment would typically have many species which are relatively rare, intermixed with a few abundant species 

Competition: a detrimental interaction between two or more organisms for an essential, but limited resource

Database: a collection of data

Functional Feeding Groups: division of animals by the way they eat

Macroinvertebrate: a group of animals without backbones which are large enough to see without a microscope

Metamorphosis: a change in body shape and structure

Complete Metamorphosis: where the young look extremely dissimilar from the adult. A non-feeding pupal stage enables radical remodeling. The needs of the young are very different than the adults’.

Incomplete Metamorphosis: where young look like tiny, wingless adults. The young’s needs are nearly the same as the adults’.

Niche: an organism’s role; the “place” of an organism which includes its habitat, and its effect on other organisms and the environment.

Procedure

* indicates when really pressed for time, then only cut this from your lesson.

Day One:
1*. Show, by flash cards or slide show, the types of insects that are commonly found in creeks.

Show typical body and mouthpart adaptations these creatures have for living in different stream niches. By using a different space or food, competition between closely related species is minimized.

2. Have students brainstorm, and list, the advantages and disadvantages of complete metamorphosis. 

[Advantages include: less competition between young and parents (more food, shelter, etc. is available); young raised in a more hospitable environment; young face different predator pressures than adults; protected even if one habitat become inhospitable; adults unable to cannibalize young; and greater specialization for each life stage.
Disadvantages include: little parental protection for young; difficulty in finding appropriate, unpolluted, adjacent habitats; and possibility of accidentally mating with close relative.]

Day Two:
1*. Divide the class into groups of three.
Using copies of an Aquatic Macroinvertebrate key [Save Our Stream’s Monitors Guide to Aquatic Macroinvertebrates highly recommended], have each student key out preserved museum specimens.
Beside each animal’s common name, have the students write a body adaptation, and then predict in which part of the creek each animal lives.
or

1*. Divide the class into groups of three and form “research teams.” Assign one of the following insect groups for each team to thoroughly research and have each team:

Draw its complete life cycle;
Classify by its scientific nomenclature (for extra credit, determine of the meanings of the scientific names), and by its feeding strategies,
Determine its niche (location usually found in the creek);
List its pollution sensitivity [see reference: SOS Stream Insect & Crustaceans card]
Record its common enemies.

Common Aquatic Macroinvertebrates List:
Stonefly (Order: Plecoptera)
Mayfly (Order: Ephemoptera)
Caddisfly (Order: Tricoptera)
Dobsonfly (Order: Megaloptera)-rare
Fishfly & Alderfly (Order: Megaloptera)-rare
Dragonfly (Order: Odonta)
Damselfly (Order: Odonta)
Aquatic beetles (Order: Coleoptera)
Aquatic caterpillars (Order: Lepidoptera)
True flies (Order: Diptera)
Clams (Phylum: Mollusca; Class: Bivalvia)
Snails (Phylum: Mollusca; Class: Gastropoda)
Planarians (Class: Turbellaria)
Water Striders (Order: Hemiptera; Family: Gerridae)

2. Each groups will give a presentation about the aquatic insect they researched so that everyone in the class knows what aquatic insects they can expect to see and how to identify the insects.

Day Three:
1. Separate students into groups of three and give each group a virtual creek.

2. The groups need to identify what the insects are then calculate the diversity index (DI) and water quality index (WQI) for their creek. 
Recommendation: To calculate WQI, use “The Streemwatch Water Bug Detective Guide” produced by the Waterboard (Sydney-Illawarra-Blue Mountain) and CSIRO’s Double Helix (see Appendix 1). A subjective opinion of a creek’s health becomes an objective number which can be directly compared to the number calculated from other creeks. To calculate DI, use J. Cairns Jr.’s Diversity Index calculation method (see Appendix 2).

3. Each group is to develop a scenario for their creek based on its water quality index and biodiversity. Have the students give a brief presentation on the insects that are present in their creek , diversity index, water quality index, and a scenario for what is happening in their creek.

Days Four & Five:
1. Go to a neighborhood stream. Locate and mark monitoring sites. (The monitoring area should contain relatively shallow, calm and fast flowing water.) Make sure the students are wearing clothing that can get wet. Remember to set boundaries.

2. Remind the students that they are on a zoological expedition, and are to find as many different kinds of creek critters as possible.

Method 1: If you want to make an insect collection
3. Give each student a net and a plastic collection jar. Remind them not to get too wet. Students can successfully search an area without getting very wet. This also keeps the area from being destroyed.

4. Help the students find different insects by looking in unusual places, under rocks, leaf litter, in the mud, etc. As insects are found place them in a dishpan with water. Collect the first one for the “zoo,” and tally the rest on the Leader’s Aquatic Insect Datasheet (see Appendix 4).

5. After about 20 to 30 minutes, gather the students and take them away from the creek where a discussion can take place. Have each student talk about a critter they found, as the insect is passed from student to student in a bug box. (Discuss where the students found the organism, what it was doing, how the students caught it, etc.)

6*. Have each student fill out a Aquatic Insect Datasheet (see Appendix 5). The insect’s common and scientific name, general habitat, outline sketch, and number found during 20 minutes. The scientific name can be written in at a later date in the classroom. Also include data about the day: Date, Time, Location, and creek name.


Method 2: If you do not want an insect collection 
3. Divide class into teams consisting of 3 to 5 members each.
Assign duties: 1 Recorder and 2 to 4 Collectors. The Collectors should be able to identify stream insects fairly well.

4. At the collection site, separate the teams so that the whole area is covered. (The teams should be given an area approximately 2 meters wide which spans the creek.)

5. All teammates first count the surface dwelling insects (mainly water striders), and fish swimming in the assigned area. Record on datasheet.

6. Recorder sets watch for 20 or 30 minutes, while Collectors get their feet wet.

7. Each Recorder shouts “GO”, and the Collectors, for the next 20 minutes, pick up stones, sticks, and leaf litter. They tell the recorder the amount and common names of all macroinvertebrates. The Recorder tallies these “critters”.

8. If an insect cannot be identified, collect it in a vial with alcohol. Temporarily label the specimen with an unique number, and continue using this number whenever you see this insect during the remainder of the day.
NOTE: Collecting unidentified insects does not count as elapsed time.

9. After 20 or 30 minutes, stop tallying stream “insects”.

10. Once in classroom, place collected unidentified organisms in glass vials with eythl alcohol. Key out the organism using the flash cards and books. Label the organisms by making a note card written in pencil and placed within each vial. The note card should be labeled as follows:

Aquatic Insects 1
Aquatic Insects 2

   Ex:  

Evaluation*:
Days Six & Seven:
1. Have each research team teach their insect group to the class by an illustrated talk. Allow the class to take notes.

Or 

1. In class, graph the macroinvertebrate data by Pollution Sensitivity: Very Sensitive, Sensitive, Tolerant, and Very Tolerant.
Also graph the data by Functional Feeding Group: Shredders, Collectors, Scrapers, and Predators. The Functional Feeding Group is the typical feeding pattern used by the macroinvertebrate. Functional Feeding Groups not only give clues to the macroinvertebrate’s trophic level, but can be used to determine the type of stream “disturbance” (either man-made or natural) occurring in the creek.
The macroinvertebrates are divided into four categories:
* Shredders eat coarse organic material,
* Collectors eat very fine organic material,
* Scrapers graze on algae, and
* Predators eat other aquatic animals.
An increase in the proportion of collectors shows organic enrichment ( maybe from increased leaf litter or dumping of waste), whereas an increase in the proportion of scrapers indicates a nutrient runoff (maybe from rains or over-fertilization).

2. Examine the graphs, and decide if your neighborhood creek is “healthy”.
Questions to help determine a healthy habitat:
Are all groups of common macroinvertebrates represented?
Is the complete food chain (herbivores, predators, scavengers, etc.) represented?

Day Eight:
1. Give a practicum to test the students ability to identify common stream insects.

Materials:

  • Common Macroinvertebrates from nearby creek or stream (i.e. Strawberry Canyon Creek) slide show set
  • Set Common Macroinvertebrates flash cards (see Appendix 6)
  • Guides to the common stream insects: [SOS’s Monitor’s Guide to Aquatic Macroinvertebrates recommended]
  • Set Museum Macroinvertebrate Specimens from Big Creek Reserve and Strawberry Canyon Creek
  • Virtual Creek paper insects
  • Handlense (one per student)

For stream or Creek collection (days Three and Four):

  • White observation cupcake tins/containers (one to two per group)
  • bug box with magnifying lens
  • 70% ethyl alcohol
  • plastic collection jars (one per student) or collections trays (one for group)
  • pencil (one per student)
  • Small fish net
  • Tweezers (one per student)
  • Extra pair of old tennis shoes
  • Change of clothes (pants, sweatshirt, socks)

Optional Materials

  • Thermometer (temperature corrected)

Possible Extensions

  • Create a class mural showing the creek creatures in their natural habitat.
  • Create a classroom stream insect guide to a local creek. Share (or sell) your guide to interested groups. Start a creek monitoring network.
  • Create a “Local Stream Insects” slide show. Show the show during a school assembly during Earth Week.
  • Have the class go to a new location, either at a different stream, or at a different section of the stream above, and repeat the procedure.
  • Determine the creek’s water quality from the data. Repeat procedure throughout the year to determine if the water quality changes.
  • If the Water Quality Index of your neighborhood stream needs improvement, hypothesize from the Functional Feeding Group. Brainstorm solutions to improve the creek’s water quality. Implement the students ideas, and monitor the creek.

References

Kellogg, Loren Larkin. Save our Streams Monitor’s Guide to Aquatic Macroinvertebrates. second ed. Gaithersburg, Maryland: Save Our Streams Program, Izaak Walton League of America, 1994. $5.00 each

Lincoln, R.J., and G.A. Boxshell. The Cambridge Illustrated Dictionary of Natural History. Cambridge: Cambridge Univ. Press, 1987.

Lawrence, Eleanor. Henderson’s Dictionary of Biological Terms. 10th ed. New York: A WIley-Interscience Pub., 1989.

Powell, Jerry and Charles L. Hogue. California Insects. Berkeley: Univ. of California Press, 1979.

Save Our Streams Program. 
Stream Insects & Crustaceans card. Gaithersburg, MD: Izaak Walton League of America, 1994.

Izaak Walton League of America
707 Conservation Lane
Gaithersberg, MD. 20878-2983
(301) 548-0150

Appendices

  • Appendix 1 – Water Bug Detective Guide (sheets 1, 2, 3, 4, and 5) and Insect Survey
  • Appendix 2 – Diversity Index
  • Appendix 3 – Bug cutouts
  • Appendix 4 – Aquatic Insect Data Sheet
  • Appendix 5 – Student’s Aquatic Insect Data Sheet
  • Appendix 6 – Download PDF