The stream environment

Brief Description

Students connect environmental conditions in the stream to habitat preferences of different macroinvertebrates.
Background for Teachers

Macroinvertebrates vary in their stream environment requirements. Some tolerate wide differences in chemistry; some do not. Some like streams with fast flowing water and a cobble-y streambed, some like slow moving water and a mucky streambed.

For example- as the amount of fine-grained sediment goes up in an area of the stream (and cobble-y substrate goes down) the total number of mayflies, stoneflies and caddisflies goes down.

It is possible that the stream characteristics above and below your research culvert may differ from one another.  How might this culvert-induced difference in stream setting affect the macroinvertebrate community?

In this activity your students will be using the information they have gathered from the Macroinvertebrate activity and stream information to find a suitable stream (or streams) for their organisms. There are three streams in the activity to choose from. These streams have different chemistries and physical settings. It is important that your students support the placement of their organisms with information from their prior research.

There are a lot of things about a stream that affect the stream as a habitat for macroinvertebrates-

  • Sunny or Shady;
  • Fast flowing or slow;
  • Wide or narrow;
  • Rocky bottom or muddy…
  • …and everything in between, often in the same stream!

A lot of these (parameters) we can easily collect data for.  Below is a list of some stream characteristics that may influence the macroinvertebrate community.

Note! This is a long list of things we can measure. It is very similar to the Table of Field Variables that you will use later in the project. You can measure any of them, but it is advisable to select only a few parameters, or variables, based on what will support your student’s hypotheses.

Physical characteristic

What it is

Why it is an important habitat consideration

What we can measure

Streambed substrate

What is on the bottom of the stream

Different organisms live in and use different substrates

Size: boulders, cobbles, gravel, sand, muck

Percent: of each of the above.

Stream bank plants

The plants that live next to the stream

These influence how much shading the stream gets (which will help determine how cold the water stays)

Some plants are better at holding stream banks together.

Some organisms use stream bank plants to lay their eggs on.

Plant type

Whether or not they shade the stream

Stream width

How wide the stream is

How much space there is in the streambed for different organisms.

Widths at different locations along the stream

Stream depth

How deep the stream is from one side to the other

Different organisms prefer different depths.

Depth across the stream from one side to the other (also in multiple locations along the stream)

Water speed

How fast the water is travelling

Speed of water will influence who can live where



The amount of water moving through a part of the stream

The amount of water moving through any part of the stream will tell us how much material is being moved from the stream system to the ocean

Using width, depth and velocity we can calculate flow.


The change in height from the top of your study area to the bottom of your study area

Slope can tell us a lot about how things can move around or live in an area

We can use a clinometer to measure slope.

Chemical characteristic

What it is

Why it is an important habitat consideration

What we can measure


How warm or cold the water is

Warm water can hold less oxygen than cold water, and because animals have different oxygen level tolerances they will be found in waters of different temperatures.



How acidic or basic the water is

Different organisms have different “preferred” and “tolerated” ranges of pH levels- pH can determine who lives where.


Dissolved oxygen (DO)

How much oxygen is dissolved in the water

Animals have different oxygen level tolerances.

Dissolved oxygen (DO)


How clear or murky the water is

Turbidity is caused by particles that are suspended in the water column- some organisms can handle turbid water, some cannot.



To review some basic terminology:


Students understand:

  • That the physical and chemical attributes of the stream influence the macroinvertebrate community


  • Become familiar with different stream chemistries and physical differences
  • Students will apply knowledge about their macroinvertebrates and use stream data to select a stream (or streams) for their organism
  • Students will use facts (from their research) to justify the stream environment(s) they have chosen for their invertebrates
  • Create three different community assemblages of macroinvertebrates- one for each stream

Where does this lesson happen in the Project?

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

Getting Ready

Most students are already familiar with streams and rivers. Solicit information that students already have about streams that they know-

  • Does your stream have trees hanging over it?
  • Is the water cold or warm?
  • What does it look like in the winter?
  • Are the rocks slippery?
  • Is it mucky?
  • What does the water looks like- clear or murky?
  • What does the streambed look like?
  • Is the particular stretch of stream straight or does it meander?
  • Is it deep or shallow?
  • Fast flowing or slow moving?
  • Wide or narrow?

Ask them to recall some of the stream requirements of their macroinvertebrates (from Activity 1: Stream Invertebrates). Alternately, instead of recall, have them refer to the information they have.

If you have gone to your study site review photos and narrative information about what your study site is like.

Your students will be using the research information for their macroinvertebrates and the stream data on the Stream Information Worksheet to find the best location for their particular organisms. It is best to have just one image for each stream for the classroom. In this way when the students are done they have a feel for whole macroinvertebrate assemblages that exist in different environments.


  • Student’s Resident Expert worksheet or presentation
  • Pictures of the different organisms from Activity 1: Stream Invertebrates
  • Stream Information Worksheet
  • Question Worksheet
  • Images of the three different stream environments

Handouts (see also Lesson Resources)

    Stream Information Worksheet
    Question Worksheet

Student Prerequisites

  • Students must have completed the first activity in the Unit (Stream Invertebrates)

Time Needed

  • 1 class period

Doing the Activity

Make sure the students have their information from their macroinvertebrate research.

The students will use the information from the three different streams and decide which stream or streams is best for their macroinvertebrate- based on their prior research.  After the students have written their reasoning for their placement of the macros they should put an image of their macro on to the classroom stream picture. There may be more than one “good” stream for some of the macroinvertebrates (and therefore you may need more than one image for some of the macroinvertebrates), but what will emerge are different assemblages of macroinvertebrates.

There may be a fair amount of overlap, but each stream community will be slightly different.


Discuss the different community assemblages, ask students to explain, to the class, their stream selection.

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 stream conditions and macroinvertebrates, or culverts and stream conditions. 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.

If your students are challenged start with a prompt- do you think that the shade from having trees over the stream would affect the macro community- why or why not? How could we test this? (chose any one of the parameters from the list above for asking this question)


  • None at this time

Lesson Extensions and Supplements

Assign your students to bring in pictures of a stream they are familiar with (or use the internet as a source for stream pictures). Use any of the physical parameters to arrange the pictures on a scale (for example “A lot of canopy cover” to “No canopy cover”).

Instead of placing their own organisms in streams have your students switch organisms so that each person is using someone else’s research to place the macroinvertebrate in a stream.

Lesson Resources

application/pdf iconStream Information Worksheet
application/pdf iconQuestion Worksheet
application/pdf iconImages of the three different stream environments