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Monitoring Creek Health
Who Is in the Aquatic Food Pyramid
and What Is Their Relationship to the
Health of an Ecosystem?
Students explore aquatic ecosystem health by building an aquatic food pyramid and creating aquatic insect field guides.
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Student Outcomes
At the end of this activity, the students will be able to:
- Measure and monitor water samples in the classroom (pH, dissolved oxygen, and temperature).
- Determine an aquatic food pyramid based on aquatic insect research.
- Create aquatic insect field guides used to monitor water quality.
- Understand aquatic insects are indicators of water quality and parts of various food chains.
California Science Standard Links (grades 6 – 8)
This activity is linked to the California Science Standards in the
following areas:
- 6th grade:
- 5a - food webs;
5b - organisms and the physical environment;
5e - resources available and abiotic factors. - 7th grade:
- 7b - utilize a variety of print and electronic resources.
National Science Standard Links (grades 5 – 8)
This activity is linked to the National Science Standards in the following areas:
- Content Standard A - Abilities necessary to do scientific inquiry.
- Content Standard A - Think critically and logically to make the relationship between evidence and explanations.
- Content Standard C - Structure and function of living systems; population and ecosystems; regulation and behavior.
- Content Standard F - Populations, resources, and environments.
- Content Standard G - Science as a human endeavor.
Materials
To be photocopied from this guide:
- Aquatic Organism Field Guide activity sheet (40K PDF document)
- Aquatic Food Pyramid activity sheet (44K PDF document)
Vocabulary
Generated by student inquiry
Procedures
- Begin a discussion of aquatic food systems
Brainstorm a list of components included in an aquatic habitat. Remember, many insects begin life in an aquatic environment. - Distribute activity sheets
Each student should receive both activity sheets. - Independent work
Students (or student teams) will be assigned or choose an insect (or other aquatic organism) from the list at the end of this lesson. It is their responsibility to complete Aquatic Organism Field Guide activity sheet for their species and to supply a picture or drawing. - Create food webs
Using the blackboard (or large sheets of butcher paper), have all students, one at a time, place their food webs (from activity sheets) on the blackboard. If a representative of their food web is already listed on the board, they should incorporate their food web with that organism. - Create food pyramid
Let the entire class examine the food web. What would be the base of the food pyramid? What would be at the top? How does the sun's energy flow through an ecosystem? Discuss the role of producers, consumers, scavengers, and decomposers. Complete an Aquatic Food Pyramid activity sheet, or draw on blackboard - Processing questions
How can a food pyramid be used to determine the health of an aquatic ecosystem? What would happen if organisms at the base went extinct as opposed to organisms at the top? Which species could potentially have the greatest positive or negative impact on this food pyramid? Define the components of this ecosystem and discuss humans' role in aquatic ecosystems. - Aquatic insects are long-term quality monitors
In a random collection of aquatic insects, some are tolerant of pollution while others are very sensitive. A stream with very few sensitive aquatic insects is probably not very healthy. - Water quality tests vs. aquatic insect surveys
What can each tell you about the health of a creek? Water quality tests will tell you about the water in that second of time. Variables can be thrown off very quickly if you test a sample that includes storm runoff from an area where someone has just washed a car. Aquatic insect surveys are indicators of long-term health. But aquatic insect surveys can be inconclusive if done at the time of the year those insects are never present (in terms of their life cycle). Each of these tests provides us with different information and complements the other. Both types of tests will be conducted on the upcoming field visit to Point Reyes National Seashore. - Create aquatic insect field guide
A field guide may be created in many forms. Following are some suggestions:
Collect all of the Aquatic Insect Organism Field Guide sheets. Assemble in a binder to be brought on the field visit. Full-sized activity sheets can be used or smaller copies laminated.
Break the class into four groups (the groups they will work with on the field trip). Each group receives a copy of all Aquatic Insect Field Guide sheets. It is up to each group to produce a field guide. Some students may scan sheets into computer and use a layout program to create a guide; some may choose to replace drawings with pictures from other sources. Remind students that what they are designing will be used on their field trip. Creativity and functionality are their guideline.
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Extension ideas
- Visit "The Stream Study" website (listed in the Resources section) to use an online key for identifying and learning about aquatic insects.
- Have students generate all the ways humans can impact water quality and the results of certain tests.
- Discuss the water cycle and the sun's role as a major source of energy.
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Association.
