Fish Ways Activities
SUMMARY
Students will use a map to discover and trace
the extent of the nearest river system and its watershed,
facilitate discussion of natural stream changes from headwaters
to mouth, and identify human impacts.
OBJECTIVES
Students will be able to:
- isolate and order any stream or river system in Ontario;
- predict the characteristics along various parts of a
stream; and
- list at least two human impacts affecting river systems.
LESSON INFORMATION
Curriculum Link: 7SLS, 7GTGI, 7GPPG, 7GNR
Setting: classroom and outdoors (optional)
Duration: 60 to 90 minutes
Key Terms: catchment, deposit, divide, erosion, first order
stream, floodplain, headwater stream, river basin, second
order stream, stream ordering, third order stream, tributaries,
turbid, valley, watershed
TEACHER BACKGROUND
River, stream, freshet, creek-there are many names for flowing
water. Some, like creek and brook, are used interchangeably;
others have unique, specific meanings. Scientists generally
refer to smaller bodies of flowing water as streams and larger
ones as rivers. The area of land from which rainfall and melted
snow drain into a particular stream or river is called its
watershed or catchment. The high ground separating watershed
is called a divide. Every place on earth is part of some watershed.
Every watershed reflects the land it drains. The quality of
water within a watershed and the species of fishes that can
be found within its boundaries are directly linked to the
quality of the land and any use it is put to by humans. As
streams join other streams, a branching network, or river
system, forms.
Stream ordering is a way of indicating in numerical terms
the relative position of a stream within a much larger river
system. Headwater streams that have no tributaries or branches
are called first order streams. They usually begin from cool
springs arising in a hillside or wetland, or as an outlet
from a lake or pond. First order streams are usually narrow,
shallow and steeply graded; they may have grasses, shrubs
or trees lining their banks, shading the stream from the sun
and keeping the water cold. They may flow quickly, scouring
the bottom of all but rocks and large particles of gravel,
and are often inhabited by cold-water-loving fish species
such as trout. When two first order streams join, a second
order stream is formed. Similarly, a third order stream is
created by the joining of two second order streams, and so
on.
Where two streams of differing orders meet, the downstream
portion retains the higher of those two orders. For example,
second and third order streams would join and form a third
order stream. It has been estimated that about 80 percent
of Ontario's trout streams are first or second order streams.
When does a stream become a river? Most scientists feel that
a third order stream can be classified as a river. The volume
of water in a river is much greater than that of a stream
and often a valley has been cut or eroded by a river's flow.
The rate of flow in a river is usually much less than in a
stream. The floodplain, or land periodically flooded by a
river, becomes flatter, and silt and sand eroded upstream
are often deposited on the bottom of the river bed as the
river slows. The river's water tends to be turbid because
of the suspended particles of clay, silt, finely divided organic
and inorganic matter, etc. It is also often warmer from exposure
to the sun and frequently contains less oxygen. Fish species
like carp, walleye, brown bullheads, channel catfish and lake
sturgeon, which have adapted to warmer water and more turbid
conditions, tend to inhabit these warm water rivers.
A river goes through a number of changes from its headwater
source to its mouth where it empties into a large body of
water such as a lake. Similarly, the character and quality
of its fish community may change as the stream order changes
and as human activity within the catchment changes.
MATERIALS
River System Master Maps (one map per student); Ontario road
maps; coloured pencils Optional: local topographic or county
maps; tracing paper
PROCEDURE
- Have students discuss all the streams, creeks, brooks
and rivers that they've seen (that is, flowing water). What
do these water bodies have in common? How do they differ?
Can these descriptions be organized in any way? For example,
do similar sized streams have similar characteristics?
- Explain that, for scientific purposes, a numerical system
has been devised to standardize the various components of
a moving water system. This numerical system may allow scientists
to roughly determine the types of fishes that may inhabit
that environment. Discuss the characteristics (water temperature,
volume, fish species, etc.) that might change as the stream
order increases from the headwaters to the mouth of the
river. Explain that the majority of trout streams are first
or second order streams.
- You may wish to have your students devise their own technique
for ordering streams or you may follow this approach. Discuss
the system of stream ordering by having the class build
a simple river system. Using the blackboard or chart paper,
have one student link two first order streams to form a
second order stream and label each. Then ask a second student
to draw a similar configuration and link it to the first
to create a third order stream - and so on until a fourth
or fifth order stream is reached. When this river system
is complete, ensure that students realize that the land
the river system drains slopes downhill from a divide as
the stream order increases, thus creating a drainage basin
or watershed. Draw a line around the river system and label
it as the watershed.
- Divide the class into small groups and give each group
a provincial road map. Have students find their own community
on the map and find the nearest river system. Select in
advance the appropriate River System Master Map provided
for your region and distribute a copy to each student. Using
the road map for guidance and the Great Lakes for reference,
have students outline their nearest watershed. Note: The
students' local community may be part of another drainage
system but the river closest to their community on the River
System Master Map should be selected.
- Using coloured pencils, have students establish a key
for their map using a different colour for each stream order
and colour their local river system accordingly. Since the
maps provided are for the Great Lakes drainage basin, all
river systems should end up in a Great Lake.
- Discuss what they know of different parts of this river
system. Are their descriptions consistent with the ordering
system used?
- From the maps and local knowledge, determine major points
of human impact (e.g. industrial plants, cattle crossing
or watering locations, stream improvement projects, storm
sewer outlets), and discuss any known changes to the river
system at those points.
- Depending on the quality of the discussion and the accessibility
of the river system, students could be assigned the task
of confirming/expanding knowledge about various points within
the system through on-site examination.
- Once the exercise is complete, discuss the following
questions with the class. As the stream order increases,
would humans' impact on the river system tend to increase
or decrease? What effect could this have on the local fish
community? Is there evidence of these effects near your
local community?
EVALUATION
Given a map of a simple watershed, have students order the
streams and give a brief description of each order.
EXTENSIONS
- To provide a more accurate stream order for the local
catchment, have students use tracing paper and local topographic
maps or county road maps if available. Once the first and
second order streams are located, contact the Ministry of
Natural Resources district office most convenient to your
school to obtain information on the fish communities in
these streams.
- Organize a field trip to visit nearby examples of different
stream orders. Record and compare stream bank conditions,
rate of flow and water temperature at each site.
- Have students find out if developers, planners and resource
managers take stream order and potential fish habitat into
consideration when building dams, highway crossings, subdivisions,
etc.
REFERENCE
Andrews, W.A., and S.J. McEwan. Investigating Aquatic Ecosystems.
Scarborough, Ontario: Prentice-Hall Canada Inc., 1987.
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