The Arizona STEM Acceleration Project

Learning Through Leaf Packs!

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Lesson 2 of 8: Stream Food Webs

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Learning Through Leaf Packs

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Stream Food Webs

(Lesson 2 of 8)

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A Middle School (6th - 8th) STEM Lesson

Susan Brown & Carrie Jenkins

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12/19/22

Learning Through Leaf Packs

Note for Teachers: This is an 8 lesson unit that is designed to be used together to learn about the health and diversity of your local watershed by placing leaf packs into a water source (natural or man-made ponds, lakes, streams, and rivers) and attracting macroinvertebrates. Links to lessons are on the next slide.

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Why do this?!

• Connection to science standards
• Engage students in the scientific process
• Authentic science
• Citizen science (Global database)
• Collaboration with community members
• Students LOVE it!!!

Carrie Jenkins, 6th math & science

You don’t need a water source. This unit has a virtual option to collect data!

Lesson Sequence

Lesson 1: What is a leaf pack?

Lesson 2: Stream Food Webs

Lesson 3: Dichotomous Keys

Lesson 4: Leaf Pack Dissection

Lesson 5: Data Analysis and the Leaf Pack Network

Lesson 6: Stream Sleuths

Lesson 7: Using Biotic Index to Infer Water Quality

Lesson 8: Chemical Water Testing to Assess Water Quality

Susan Brown, 7th science

Notes for Teachers

• Lesson will take one 50-60 minute class period.
• Lesson will familiarize students with benthic macroinvertebrates for leaf pack lesson.
• Students will create a food web of a stream ecosystem using macroinvertebrate cards.

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List of Materials

• markers
• chart paper
• organism cards (Acorn Naturalist or Leaf Pack Network Steam Ecology Kit)
• Presentation embedded in this lesson plan

Arizona Science Standards

6.L2U1.13 Develop and use models to demonstrate the interdependence of organisms and their environment including biotic and abiotic factors.

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6.L2U1.14 Construct a model that shows the cycling of matter and flow of energy in ecosystems.

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Science & Engineering Practices

• ask questions and define problems
• develop and use models
• plan and carry out investigations
• analyze and interpret data
• use mathematics and computational thinking
• construct explanations and design solutions
• engage in argument from evidence
• obtain, evaluate, and communicate information

Arizona Science Standards

Life Science Standards

Students develop an understanding of the flow of energy in a system beginning with the Sun to and among organisms They also understand that plants and animals (including humans) have specialized internal and external structures and can respond to stimuli to increase survival.

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6.L2U3.11 Use evidence to construct an argument regarding the impact of human activities on the environment and how they positively and negatively affect the competition for energy and resources in ecosystems.

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Core Ideas

6.L2U3.12 Engage in argument from evidence to support a claim about the factors that cause species to change and how humans can impact those factors.

● Ecosystems are dynamic in nature, their characteristics can vary over time. Disruptions to any physical or biological component of an ecosystem can lead to shifts in all its populations.

● Human activities have significantly altered the biosphere, sometimes damaging or destroying natural habitats and causing the extinction of many other species.

Objective(s):

• Today we will learn about a stream food web.
• Today we will learn about the roles that organisms play in a stream ecosystem.

Agenda (1 class period)

1. What are the major players in a stream food web?
2. Shredders, collectors, scrapers, predators
3. Create a foodweb of a stream using common macroinvertebrates.

Intro/Driving Question/Opening

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What is the role of macroinvertebrates in a stream ecosystem?

We categorize benthic macroinvertebrates by their job.

Do they break apart leaves, eat the shredded and broken down leaf material, do they eat other macros?

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Four main categories:

• Shredders
• Collectors
• Grazers/Scrapers
• Predators

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Examples of the 5 main functional feeding groups: filter feeders, predators, shredders, scrapers, and collector/gatherers.

Shredders

• What does the word “Shredder” imply?
• Examples of shredders in the Southwest include the caddisfly (Heteroplectron californicum) and the stonefly (Zapada cinctipes)
• Shredders are responsible for processing coarse particulate organic matter (CPOM). CPOM is greater than 1 mm in size and typically derived from allochthonous sources, such as woody debris, leaves, and other vegetation from the neighboring riparian corridor. Examples of shredders in the Southwest include the caddisfly (Heteroplectron californicum) and the stonefly (Zapada cinctipes).

What shredders eat!

Collectors

• What does the word “Collector” imply?
• Collectors filter and collect smaller particles of organic matter (FPOM) found in the water column and bottom sediments. FPOM can range in size from 0.01-1.0 mm and usually arrives in water columns and benthic sediments as a result of CPOM being broken up by shredder species. Examples of collector species include the beetle (Zaitzevia parvula) and the Dipteran (true flies) (Antocha monticola).

Whirligig Beetle - an overview | ScienceDirect Topics

Chironomidae (Midges) True Fly Larva Pictures

Fine particulate organic matter (FPOM) transport and processing in littoral interstices – use of fluorescent markers - ScienceDirect

Collectors eat this!

Scrapers/Grazers

• What does the word “Scraper/Grazer” imply?
• Grazers are found on rocks and woody debris, feeding on periphyton, detritus, and submerged aquatic plants. Most gastropods (snails) are grazer species; other grazers in the Southwest include the caddisfly (Helicopsyche borealis) and the beetle (Optioservus quadrimaculatus).

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Lunged Aquatic Snails (Pulmonate Pond Snails) | Missouri Department of Conservation

https://www.winonaflyfactory.com/caddis-fly-entomology-pt-3/

Aquatic plants: unsung but prime salmon habitat | California WaterBlog

Scrapers eat this!

Predators

• Predators prey on animal tissue. The primary food sources for this group are other aquatic macroinvertebrates. Many southwestern dragonflies, such as the riffle darner (Opolonaeschna armata) and Pacific spiketail (Cordulegaster dorsalis), are voracious predatory species.

Common Green Darner (U.S. National Park Service)

Arizona’s Fish Species – Anglers United

Hands-on Activity Instructions

• Learn the different jobs of macroinvertebrates in a steam food web.
• Make your own food web using the cards provided.
• Remember arrows show the flow of energy and go from the food to the eater.

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Let’s look at the example on the right to remember what we have learned about food webs.

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What gives energy to the fox? What role does the fox play?

Assessment

Food Web:

On your chart paper, you need to create a food web of stream organisms. You need to correctly show the flow of energy through the aquatic ecosystem by using arrows.

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*Note: use pre-printed cards with organisms to create food web or make your own. If you have students make cards, laminate then and use them for future years. You can also have student research online.

Differentiation

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Prior to students making the food web, you can categorize organisms based on their role in the ecosystem: producers, predators, prey, decomposers, primary consumers, secondary consumers, and tertiary consumers.

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Students can make a food chain instead of a food web.

Remediation

Extension/Enrichment

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Students can add in additional organisms that are part of the local ecosystem in the surrounding area.

Students can research endangered species in a local ecosystem (AZ fish for example that rely on macros).

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Useful Links & Resources

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Macroinvertebrate cards for purchase here:

Nature Circles® Pond & Stream Life Card Set

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Macroinvertebrate cards also available at LaMotte:

https://lamotte.com/aquatic-macroinvertebrates-insect-identification-flashcards-5882-sa1

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• Plastic mesh bags
• 1 6″ sieve, 500 micron mesh
• 1 MacroLens™,
• 1 set of 6 Laminated, Spiral-Bound Freshwater Macroinvertebrate Dichotomous Keys
• 1 set of 6 Biotic Index Data Sheets,
• 30 feet of nylon twine to secure your leaf packs in the stream
• 60 Petri dishes or similar clear dishes to place on sorting sheets
• 12 artist’s paint brushes
• 6 plastic sorting trays
• 6 hand lenses
• 12 plastic spoons
• Dried tree leaves, 180g (30g per leaf pack)
• 1 hand-held scale or digital kitchen scale, to weigh leaves for leaf packs
• Dissecting microscope
• Buckets

Stream Ecology Kit

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“Leaf Pack Stream Ecology Kit.” Stroud Water Research Center, 12 Mar. 2020, stroudcenter.org/product/leaf-pack-kit/

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