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Unit Plan: Stream Ecology Lesson: 2 Time: 40 minute lesson Setting: Classroom Objectives:

Students will be able to discuss habitat needs and feeding habits of specific macroinvertebrates and understand connections that exist between the aquatic and terrestrial ecosystem.

Overview
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Lesson Overview:
  1. Students share what they learned about macroinvertebrate taxa.
  2. Students participate in an activity that helps them understand what abiotic and biotic conditions affect the populations of macroinvertebrates in the stream
Materials:

For the whole class:

  • prepared leaf pack or kick net for demonstration
  • preserved or live specimens of macroinvertebrates

 

 For individual groups:

  • Leaf pack Challenge worksheet/kick net challenge worksheet

Engage:

  1. Have students group together based on the macroinvertebrate they researched for homework.
  2. Give students two to three minutes to discuss what they found out in regard to feeding habits and habitat preference within their group. 
  3. Ask students to share with the class their macroinvertebrate card and answers to question prompts “Where do I live in the stream?” and “How do I eat?.  As students come up to share their information, project on a screen an image of the organism (using Insect Photos powerpoint).   Students can share their information individually – for small class sizes OR in groups (students who researched the same organism) –for large class sizes.
  4. Students now have the opportunity to observe live and preserved specimens of the macroinvertebrates they researched.  These specimens should be set up beforehand on a table that students can walk around, with cards identifying each organism.  Be sure students carefully observe mouthparts, gills and other breathing structures.  Walk around with students and remind them to think about how the physical characteristics of the organism might help them live in their preferred habitat, gather food, etc.

 

Explore (This lesson should align with the appropriate protocol being used during the lesson 3 field trip - Leaf packs OR kick nets):

LEAF PACKS:

  1. Show students a leaf pack that has not been put in the water.
  2. Ask them:  What do you need to know to come up with a really good answer to the question  -   What organisms will you find living in this leaf pack if we put it into the stream today and retrieve it in three weeks?”
  3. Hand out the “ Leaf Pack Challenge Worksheet” and ask students to fill in abiotic and biotic factors that they would need to know to answer the above question  “ What organisms will you find living in this leaf pack if we put it into the stream today and retrieve it in three weeks?” Tell them to be as specific as possible and think as broadly as possible.   Give students several minutes to think about and write down their responses individually.   Their responses should include ideas that show they are thinking about the abiotic characteristics of the stream, such as: water temperature, time of year, water flow.  Their responses might also include ideas about biotic factors of the stream, such as:  presence of predators, competitors, food source, etc. 
  4. *****It is important that students think about what they need to know to answer the question and don’t try to actually answer the question.  If students seem confused by this you may want to model the process. For example, you can do the same activity as a class, with a simple question such as, “What would you need to know to answer the question… “Can we go on a picnic this Saturday?” *****
  5. Students can be paired up to share their lists (for small classes) or can share their ideas in a class discussion.  As a small group or class, make a diagram, concept map, or graphic organizer that helps organize their thinking about how to answer the question.  Their diagram should help them explain how to think about the question to someone else.
  6. Tell students that they will be participating in a study at the Cary Institute that will involve collecting organisms using leaf packs.  They will be collecting data on the numbers and types of organisms they find in the stream as well as the environmental conditions in the stream.

 

KICK NETS:

  1. Show students a kick net or a photo of a kick net if you do not have access to one.  (Photos can be easily found by doing and internet image search for "Bottom Kick Net".)
  2. Ask them:  What do you need to know to come up with a really good answer to the question  -   What will you find in your kick net if you hold it on the bottom of the stream for 20 seconds, while kicking the mud and rocks in front of the opening?”
  3. Hand out the “ Kick Net Challenge Worksheet” and ask students to fill in abiotic and biotic factors that they would need to know to answer the above question  What will you find in your kick net if you hold it on the bottom of the stream for 20 seconds, while kicking the mud and rocks in front of the opening?” Tell them to be as specific as possible and think as broadly as possible.   Give students several minutes to think about and write down their responses individually.   Their responses should include ideas that show they are thinking about the abiotic characteristics of the stream, such as: water temperature, time of year, water flow.  Their responses might also include ideas about biotic factors of the stream, such as:  presence of predators, competitors, food source, etc.
  4. *****It is important that students think about what they need to know to answer the question and don’t try to actually answer the question.  If students seem confused by this you may want to model the process. For example, you can do the same activity as a class, with a simple question such as, “What would you need to know to answer the question… “Can we go on a picnic this Saturday?” *****
  5. Students can be paired up to share their lists (for small classes) or can share their ideas in a class discussion.  As a small group or class, make a diagram, concept map, or graphic organizer that helps organize their thinking about how to answer the question.  Their diagram should help them explain how to think about the question to someone else.
  6. Tell students that they will be participating in a study at the Cary Institute that will involve collecting organisms using kick nets.  They will be collecting data on the numbers and types of organisms they find in the stream as well as the environmental conditions in the stream.

 

Explain:

  1. Many small animals, called macroinvertebrates (lacking a back bone), live in aquatic environments, including streams and rivers. Some macroinvertebrates live in streams continuously, such as snails, freshwater clams and mussels, and crayfish. Aquatic macroinvertebrates also include insects, such as dragonflies, damselflies and mayflies, which spend the early stages of their life in the water.
  2. There can be a great diversity of life in streams, but this diversity is strongly affected by the terrestrial environment. Streams receive many food inputs from the terrestrial environment, including leaves and woody materials from terrestrial plants.  Microscopic organisms (bacteria, fungi, algae) in aquatic environments colonize the rocks and  plant materials that collect on the bottom of the stream. The coating growing on these surfaces is called a “biofilm”. Aquatic invertebrates are classified into function groups based on what they eat. Aquatic invertebrates that readily feed on biofilms are called grazers or scrapers. They use rasping mouthparts to scrape the coating of alga, fungus and bacteria off of leaves and other surfaces in the aquatic environment. Organisms that feed on the larger pieces of organic matter (leaves) are called shredders. Those that eat the smaller pieces of organic matter, the leftovers that were processed by the shredders, are called collectors. Predators are organisms that prey on smaller insects in the aquatic environment. See table below for classifications. 
  3. Aquatic environments also provide valuable food sources for terrestrial organisms. Some bird and spider species rely on the adult insects that emerge from streams in the spring and summer as important food sources. Fish, and other invertebrates such as crayfish and mollusks, are prey for many animals, such as raccoons, otters and birds. Ducks and geese feed on aquatic plants and alga. 
  4. In addition to food inputs, terrestrial environments affect stream diversity by influencing water quality. For example, a heavily shaded stream in a forested environment will have cooler water than a stream that has much of its area exposed to sunlight, such as one running through a field or meadow. Warmer streams may have lower levels of dissolved oxygen, which some aquatic invertebrates needs for respiration. A stream in a more developed environment may have greater inputs of runoff from roads, parking lots, etc. This would influence water clarity and pollution levels. Some macroinvertebrate species are very sensitive to water quality. Therefore, macroinvertebrate assemblages can give us insight into the water quality of a stream.

 

Feeding Group Food Source Habitat Found  Major Groups/Taxa
Predators Other Animals Pools, Riffles, and Runs Stoneflies, Dragonflies, Damselflies, Dobsonflies, Alderflies, Caddisflies, Leeches, Planaria
Scrapers Algae, bacteria, anything they can scrape off Pools Water beetles, snails
Shredders Bacteria and fungi on leaf surfaces ("biofilm"). They tear up leaves into small pieces (detritus) Riffles Crane flies, Caddisflies, Stoneflies, Scuds
Collectors-Gathering Small pieces of food and organic matter, like broken up leaves along the stream bed Pools, Riffles True flies, Mayflies, Sowbugs, Crayfish, Clams and Mussels, Aquatic earthworms
Collectors-Filtering Small pieces of food and organic matter floating in the water column, like broken up leaves Runs/pools Net-spinning Caddisflies, Blackflies

 

Extend: 

  1. Have students write a response to a prompt in a homework assignment- A landowner would like to cut down some trees along a stream on his property. How will this influence the aquatic environment (abiotic and biotic factors)?
  2. Have students write a cinquain about a macroinvertebrate of their choice. Additionally students may perform and interpretive dance to go along with their poem!
  3. The format for a cinquain is as follows:

 Line 1: one word (subject or noun)
 Line 2: two words (adjectives) that describe line 1
 Line 3: three words (action verbs) that relate to line 1 (can be a phrase)
 Line 4: four words (feelings or a complete sentence) that relate to line 1
 Line 5: one word (synonym of line 1 or a word that sums it up)

                                    Example:

                                                      Mayfly

                                                      Small, drab

                                                      Gathering its food

                                                      Always waiting for spring

                                                      Collector

 Evaluate:

  1.  Responses to the “What do you need to know” exercise can be used  as a formative assessment to evaluate students understanding of how environmental conditions affect the biota of a stream and the connections that stream organism might have with the surrounding terrestrial environment.
Lesson Resources:
Benchmarks for Science Literacy: 5A Diversity of Life 5D Interdependence of Life 5E Flow of Matter and Energy 9B Symbolic Representation 12D Communication Skills 12E Critical-Response Skills NYS Standards: MST 1 - Mathematical analysis, scientific inquiry, and engineering design MST 4- Physical setting, living environment and nature of science MST 6- Interconnectedness of mathematics, science, and technology (modeling, systems, scale, change, equilibrium, optimization) MST 7- Problem solving using mathematics, science, and technology (working effectively, process and analyze information, presenting results)
Next Generation Science Standards
Science and Engineering Practices: Asking questions and defining problems Construction explanations and designing solutions Obtaining, evaluating, and communicating information

Developed and written by Jen Rubbo and Andrea Caruso