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Introduction to Zebra Mussels

Unit Plan: Ecosystems in Action: Population & Community Dynamics, Invasive SpeciesLesson: 1 Time: One 45 minute lesson Setting: Classroom
6-8, 9-12Hudson River Ecology
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Students will know what lives in the Hudson River, and will be able to create a food web drawing to represent the organisms living in the river. They will also know that the Hudson River food web is changing in response to the zebra mussel invasion, and will be able to make predictions about how native organisms will be affected by this invasion.  


    1. Students will create an ecosystem diagram of the Hudson River.

    2. Students will expand their knowledge of the Hudson River food web through a class critique of their ecosystem diagrams.

    3. Students will view the base of the food web using microscopes.

    4. Students will watch a video from the AMNH River Ecology website describing the invasion of zebra mussels into the Hudson River and the invasion’s effects on Hudson River food webs.

    5. Students will read two passages explaining the ecology of the zebra mussel and its impact on the Hudson River ecosystem.  


    • Post-it notes
    • Copies of student worksheets (“Introduction to zebra mussels” and “Exploring a population”) and Resource Sheet (“River Ecology Variables”)
    • Materials on the AMNH River Ecology site:
    • AMNH reading passages 1 and 2 (suggested homework)
    • AMNH Hudson River Ecology Video part 1 and part 2 (via internet)
    • Presentation slides “Lesson 1 Slides: Success of Invasives” and slide notes
    • Microscopes OR videos of microorganisms:

    Option 1: Demo slides (real organisms) can be purchased from Connecticut Valley Biological (, or Carolina ( )

    Option 2: Videos


    1. Begin by asking a formative assessment question: What lives in the Hudson River? Ask students to sketch, individually or in pairs, a food web for the Hudson River.
    2. Once they draw their food webs, students can view and critique a partner’s food web. Discuss what students have created, and create a class-wide food web on the board.  One way to do this is to hand out post-it notes to each pair of students and ask them to write down, or draw, a representative organism and place it on the board.  You can then add in arrows to represent the flow of matter and energy.  Ask students to think about which parts of the created web may be missing organisms or missing links between organisms (students often do not include plankton, detritus, or bacteria). Students should save their webs in order to add to them later (Sample Food Web Diagram attached).



    1. Students will become more familiar with the base of the Hudson River food web by viewing demoslides, cultures, etc, of various plankton specimens using microscopes (or, students will watch videos of common plankton).  Students could make drawings of these organisms to add to the food web diagrams. 
    2. Based on these observations, ask students to add to the class Hudson River food web diagram. 
    3. Hand out the worksheet “Introduction to zebra mussels”. 
    4. Students will watch the AMNH Hudson River Ecology video which introduces the zebra mussels Before viewing the video, ask students to make a claim about how the zebra mussels will impact the Hudson River food web on the worksheet provided (“Intro to zebra mussels”).  video:…
    5. Students will then watch Part 2 of the video series. This video introduces research that is being done to explore the effects of zebra mussel invasion. Students can answer questions about this research on the worksheet.
    6. A powerpoint is available to support this discussion – it includes an overview of common characteristics of invasives, costs of invasion, and a brief introduction to the zebra mussel life cycle. 



    1. Viewing the base of the food web, either with microscopes or with videos, allows students to build knowledge about this important part of the Hudson River.  Once students have added the organisms they observed to the class food web, ask students to add in the energy arrows. 
    2. Students often overlook or are not familiar with the importance of inputs from the terrestrial system (e.g. vegetation), along with the microorganisms that decompose them. This is an important part of most aquatic food webs, including that of the Hudson River. In the Hudson, inputs from the watershed account for 90% of the carbon that is available (phytoplankton provides about 2%, and rooted plants about 6%).  Leaves and organic matter that enter the river from the terrestrial environment are decomposed by bacteria. Bacteria, the “biofilm” it creates on the surface of dead organic material, and broken down bits of organic matter are all important food sources for microzooplankton (tiny aquatic invertebrates). In turn, zooplankton are an important source of food for fish. Students should add the terrestrial inputs to their food web diagrams. The following is a simplified version of the Hudson River Food web which appears in the AMNH Hudson River Ecology videos. Notice that the base of the food chain is made up of both aquatic and terrestrial energy sources.
    3. Phytoplankton is a blanket term for one-celled organisms, mostly protists, which have the ability to photosynthesize. While these primary producers are a food source (mostly for filter-feeding organisms) they also help oxygenate the water.
    4. Zebra mussels are small, filter feeding, aquatic mollusks that were introduced to the Hudson River in the early 1990s. While there are other species of filter feeding mollusks native to the Hudson River, the zebra mussels have had a more significant impact on the river since their introduction. Zebra mussels are small, cryptic and they are prolific reproducers. They can easily be spread by humans- attaching themselves to the hull of boats, being transported as larvae in bait buckets, etc. They attach themselves firmly to hard surfaces on the riverbed with a mass of thread-like strands called a byssus, which makes them hard to dislodge.
    5. Cary Institute researchers have been exploring conditions in the Hudson River Estuary before and after zebra mussel invasion. Zebra mussels were 1st recorded in the Hudson River in 1992, but scientists had been monitoring biotic and abiotic conditions in the river since 1986. Accordingly, they were able to make predictions about how the zebra mussels would affect the river, and look for evidence of change over time once it arrived.



    1. Students will research an aquatic organism for homework, and share information with classmates on Day Two. Students should be assigned their organisms so that at least two students research each organism, forming an “expert group”. A handout is provided with websites that students can use for research.  Students will then convene with their “expert group” on Day Two to share what they learned, and complete a graphing exercise. Students should use the attached worksheet (“Exploring a population”) as a guide for their research.
       Example Organisms
      1Sphaeriidae (native, freshwater clams)
      2Phytoplankton (e.g. Euglena, Volvox)
      3Rotifers (microzooplankton)
      4Alosa (open water fish)
      5Cladocera (macrozooplankton)
      6Centrarchidae (shallow water fish)
      7Bacterial abundance (decomposers of detritus and organic material)
      8Copepods (macrozooplankton)
      9Copepod nauplii (larval macrozooplankton)
      10Unionidae (freshwater pearly mussels)
    2. Students should come prepared to discuss what they learned with their expert groups tomorrow.*(More on Jigsaw Teaching Technique at
    3. Reading AMNH River Ecology Passages 1 and 2 prior to their second class day will give students background about the Hudson River food web, as well as information about zebra mussels (including the life history traits that researchers consider when making predictions about what effects it might have on the ecosystem). Students can answer the questions at the end of these passages, or they can be used as guidelines for review at the beginning of Lesson 2.
    4. Students can play a game teaching them about different types of invasive species, found here: (Introduction to Invasive Species lesson)


    1. Assess student understanding of the materials presented in the videos by having them share answers from their worksheet (“Intro to zebra mussels”).
    2. Students can share claims about the impacts of zebra mussels on the Hudson River ecosystem- can be discussed in class, submitted via their worksheet, or as an exit ticket, etc. 

    Lesson Files

    Zebra Mussel Lesson 1 Reading Passage 1-higher
    Zebra Mussel Lesson 1 Reading Passage 2- higher
    Zebra Mussel Lesson 1 Reading Passage 1- lower
    Zebra Mussel Lesson 1 Reading Passage 2- lower
    Zebra Mussel Lesson 1 worksheet- Exploring a Population
    Zebra Mussel Lesson 1 worksheet- Intro to ZM
    Answer key- Explore pop
    Answer Key- Intro to ZM
    Lesson 1 slide notes
    Success of Invasives PPT
    River Ecology Variables

    Benchmarks for Science Literacy

    1B Scientific Inquiry, 2A Patterns and Relationships, 5A Diversity of Life, 5D Interdependence of Life, 5E Flow of Matter and Energy

    NYS Standards

    MST 4- Physical setting, living environment and nature of science, MST 6- Interconnectedness of mathematics, science, and technology (modeling, systems, scale, change, equilibrium, optimization)
    Next Generation Science Standards

    Science and Engineering Practices

    Asking questions and defining problems, Engaging in argument from evidence, Obtaining, evaluating, and communicating information

    Cross Cutting Concepts

    Stability and change

    Disciplinary Core Ideas

    LS2A: Interdependent Relationships in Ecosystems
    New York State Science Learning Standards

    Performance Expectations

    MS-LS2-1. Analyze and interpret data to provide evidence for the effects of resource availability on organisms and populations of organisms in an ecosystem., MS-LS2-2. Construct an explanation that predicts patterns of interactions among organisms in a variety of ecosystems., MS-LS2-4. Construct an argument supported by empirical evidence that changes to physical or biological components of an ecosystem affect populations., HS-LS2-1. Use mathematical and/or computational representations to support explanations of biotic and abiotic factors that affect carrying capacity of ecosystems at different scales., HS-LS2-2. Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales.

    Materials from the American Museum of Natural History's River Ecology program.