Background for Teachers

What are culverts designed to do? How is it that some culvert designs do not affect stream functioning while other do? For your students to develop an understanding of how culverts work, and why we are researching how different culvert designs might affect macroinvertebrate communities they will need an introduction to culverts.

In this activity your students:

• Review some available information about culverts
• Participate in a class discussion about culverts and the way culverts and streams work

Culverts are structures that allow water to flow under roads. They can be metal or plastic pipes, concrete tubes, or even archways that look like bridges. They exist at the intersection of two systems—the waterway system that many wild animals use as their highway system; and, the road system in our communities.

Originally, the culvert selected for each road crossing was selected with flood events in mind. In other words- will the culvert work to move water under the road and keep the road intact during a flood? Most culverts work very well to keep the road system working. But, many people have found that culverts that are too small, the wrong shape, or in the wrong place can damage their river or stream system.

Not all culverts were designed with animal habitat in mind. But, from the wildlife perspective, rivers and streams are superhighways. Waterways move organisms like fish and macroinvertebrates and the nutrients those organisms need to live. But:

• Culverts can also have a drop-off at the lower end that is too high for fish to jump up to. Not to mention amphibians or macroinvertebrates that also use the streams and rivers as their homes and highways.
• When it rains culverts can channel water like water in a garden hose (and often like when you turn the hose on fully), but because of the small size of many culverts water can also pool on the upstream side. Instead of a stream that flows naturally we get streams that are pools and garden hoses, with a washed out streambed at the lower end (take that garden hose, turn it on full blast and aim it at a spot of dirt in your yard- what happens?).
• Culverts can also create new space for predators- such as spiders- to lay in wait for new prey.

This is an instance of fixing one system, without realizing what will happen to the other system in question. For our research larger research question it is also an incredible way to look at how different stream ecosystems are affected by an alteration. But alterations that vary in design, construction, age, and maintenance.

Our research focuses on macroinvertebrates but it is important to keep in mind is how the river responds to floods and drought, what the bottom of the river looks like, what its banks look like, how fast it flows, how deep it is… all of these are important in their own right AND they will be some of the abiotic factors that influence the community.

It is important to note that much of what you will read and see about culverts pertains to how they might affect fish movement. Much of our research is only indirectly related to fish- what will they find for food above or below culverts?  What will environmental conditions look like for the fish above and below culverts? It is important to remember that what we are studying is important to fish, but it is just as important to the overall health of the stream.

Goals

Students understand:

• The basics of culverts
• Some of the ways in which culverts may affect stream ecosystems

Outcomes

• Students review culvert basics are involved in a class discussion of how culverts work in the stream environment
• Students will be able to explain at least one way in which a culvert may inhibit natural stream ecosystem functioning and at least one way in which a culvert is neutral in natural stream ecosystem functioning

Where does this lesson happen in the Project?

This is the second activity in Unit 2- Stream Invertebrates Culverts, and the Stream Environment.

Getting Ready

This activity is a class discussion on culverts. There is a culvert overview poster and video for your students to read and watch prior to the class discussion. To get the students thinking about culverts, you might begin with a discussion to elicit what they already know or think:

• Describe your route to school this morning
• Did you notice going over any streams, rivers, dried up streambeds
• How does the water get under the road
• What lives in the stream
• Do you think those (animals, whatever the students say) move back and forth under the road

Something to keep in mind!

There are a lot of culverts in Maine, some function extremely well. It is important to remind students that culverts are not ‘bad’ or ‘good’ they are part of a system (two systems, actually), and we are researching the affect of one part of a stream system (the culvert) on another part of the stream system (the stream macroinvertebrates).

Materials

• Student Culvert Questions worksheet
• Stream Crossings Poster

(Note: This is the best text resource to start with. It is a poster produced by Commonwealth of Massachusetts, Executive Office of Environmental Affairs, and Department of Fish and Game and provides a good graphical overview of some common problems associated with culverts.)

• Computer and access to: “Connecting Fragmented Rivers” video: (3:08 minutes)

(Note: This video is great in that it features non-fish species and was made in New England.)

Handouts (see also Lesson Resources)

    Student Culvert Questions worksheet
    Question Worksheet

Student Prerequisites

• Students should know what a stream is
• Students should know that some organisms depend on the stream environment for part or all of their lives

Time Needed

• 1 class period

Doing the Activity

Hand out the worksheet and copies of the poster. Watch the video. Use the worksheet as a guide to a class discussion on culverts and streams.

Assessment

Formative

Ask a question; design a way to answer the question.  Using the question worksheet, ask students, individually, or in groups, to write down as many questions as they have about culverts or culverts and macroinvertebrates. From the list of questions have the students choose one or two. Ask the students to design a method to answer the question.  If there is time- present some of the questions and designs and discuss the merit of the research design.

Summary: None at this time

Lesson Extensions and Supplements

Ask students to find culverts near their houses and draw or take pictures of them.

Ask students to tally how many culverts they can find on their way to school.

There are many other web-based resources about culverts- some are very technical, some are very biased. This may be a good time to have your students do some Internet research to find more culvert information (although there are a lot of excellent videos about culverts there are a couple of culvert zombie videos… be ware).  It is also an excellent time for students to critically evaluate to quality of the web-based information they are using. Here is one example of a web-information evaluation lesson plan:

Lesson Resources

    Stream Crossings Poster
    Student Culvert Questions Worksheet
    Question Worksheet
    “Connecting Fragmented Rivers” video: