Investigating Crayfish and Freshwater Ecosystems, Lesson 2 Invasive Crayfish and Community Changes

Engage students and encourage them to apply prior knowledge by asking what they would do if they discovered that native crayfish and other macroinvertebrates (small animals without backbones) seem to be less common in a nearby stream, while some new crayfish species are appearing there.

Ask students to think about what research project(s)/tests they might conduct to get more information, who they might talk to about it, and what other problems might be related to the issue. Tell them they will have a few minutes to brainstorm their ideas with a neighbor, recording them on paper or with an electronic device in words and pictures.

Circulate through the groups, answering (and asking) questions to help students arrive at their own conclusions. After a few minutes, tell students they will have one more minute to brainstorm and to be prepared to share their best ideas with the class.

Allow the groups to share their ideas and tell them that they will be working with a partner to graph some data to learn about the issue. 

Ask students to form groups of 2–3 while you pass out the “The Mystery of the Changing Crayfish Populations” activity sheet. Ask them to first read through the scenario. Explain that after they finish reading, they should work together to graph the data and answer the questions in the “Your Challenge” section.

Tell students they should conduct additional research, as necessary, to determine what roles each of the species listed in the table play in the Great Lakes ecosystem. They may use the Internet and other available reference sources; they should cite the sources they use for additional information. 

Circulate through the room answering (and asking) questions, helping the groups get started. Encourage students to use reliable sources to research the organisms listed in the table on the student activity sheet. Suggest sites listed in the Expand Knowledge + Skills and Resources sections, if needed.

Allow students time to complete their investigation outside of class, if necessary.

Once students have completed their research, ask a group to share their graph of organism abundance during a full class discussion. Ask other groups if their graphs are similar and discuss different ways of displaying data.

Ask students to share their observations about what is happening to organisms in Large Lake. Consider asking different groups to share what they discovered about each organism listed in the table.

Write the terms “native species” and “invasive species” on the board. Ask students if they know what these terms mean and how the terms were used in sources they found through their research. Ask students if they have heard about any other invasive species found in the U.S.

If students haven’t already mentioned that Rusty and Red Swamp Crayfish are invasive species found in Large Lake (and the Great Lakes), share that information. Ask students what impacts these two crayfish species might be having on the other species in Large Lake, based on the data.

Ask students to think about the different ways an invasive species could negatively impact a native species. Help them understand that invasives can outcompete natives for space and food, introduce new diseases, and disrupt an entire ecosystem.

Students can complete the “Invasive Species Project,” explained on the handout following the lesson plan, including the creation of fun “Wanted” posters.

Ask students to read “Native & Invasive Crayfish of the Great Lakes Region” found in the introduction of this curriculum. They can use it as a reference to help them compare two crayfish species. This can be done using a graphic organizer such as a Venn diagram and/or a written analysis.

Have students read cartoons about invasive crayfish and/or create their own cartoons. Excellent examples and ideas are listed in the “Stone Soup: Invasive Species and Cartooning” lesson plan found in the materials block above.

Show some or all of the TED-Ed Animation “The Threat of Invasive Species–Jennifer Klos” found in the materials block. Ask the students to work through the “Think” questions with a partner, recording their ideas in science notebooks or via the online system. Discuss their ideas as a class and/or through the discussion board accessed via the “Discuss” link.

For younger and/or less experienced students, consider reading through “The Mystery…” scenario as a class and answering questions before forming groups to work on the project.

Investigate the biodiversity of macroinvertebrates in a nearby stream to evaluate water quality based on the prevalence of different species. You can also help to improve water quality by doing a service project such as planting native plants or removing trash. Good activities to support this field work are found in:

• “Stream Side Science” lesson plans from Utah State Univ. Extension Service: extension.usu.edu/waterquality/files/Stream-Side-Science.pdf
• SOLVE’s Environmental Service-Learning curriculum: engagingeverystudent.com/project/solve-environmental-service-learning-curriculum

Invite students to create public service announcement videos about ways to help keep invasive species of animals and plants out of our ecosystems. 

Review student research projects and answers to the questions.

Use student participation in class discussion and activities to determine student understanding.

Ask students to reflect on the lesson in writing and/or orally, including about what they learned and what you, as the teacher, might do to improve the lesson next time.