SMALL STREAM HABITAT ASSESSMENTS
ECOLOGY OF LARGE RIVERS LABORATORY

Location: Pleasant Valley Creek
Objective: Assess stream habitat characteristics of two sites on a small stream in and near Winona
Hypothesis: Physical characteristics do not differ between upstream and downstream locations on Pleasant Valley Creek.

Agenda:
1) Take measurements of stream width approximately every 5 m.

2) At each width measurement, measure water depth (cm) and current velocity (at 0.6-depth) at five locations spaced evenly across the stream.

3) At every spot where water depth and current velocity are measured, determine substrate composition by identifying the major substrate type within a square-foot patch. Use the following guide:

Bedrock - large mass of solid rock

Boulder - over 10" in diameter

Rubble - 2" to 10" in diameter

Gravel - 1/8" to 2" in diameter

Sand - less than 1/8" in diameter

Silt - fine material with little grittiness

Clay - compact, sticky material

Detritus - organic matter, e.g., sticks, leaves, etc.

Vegetation – submersed and/or emergent vegetation within the water

4) Measure the dimensions (length x width) of any logs/branches, boulders, and undercut banks that may be used as cover by trout. Measure these anywhere they occur in the stream, not just where you measure stream widths.

5) Determine the total length of stream surveyed.

6) Measure the distances (m) between adjacent riffles (upstream edge to upstream edge).

Analysis:
1) Calculate means and standard deviations for width, depth, current velocity, and riffle spacing at each stream site, and statistically compare the means between sites using t tests (use the two-tailed P values).

2) Group your water depth measurements into 10-cm depth categories (0-9, 10-19, 20-29, etc.) and your current velocity measurements into 10 cm/sec velocity categories (same as above). Create two frequency histograms comparing 1) depths between stream sites, and 2) current velocities between sites.

3) Calculate the total area of stream assessed at each location (length x average width).

4) Determine the total areas of each of three types of fish cover: logs/branches, boulders, and undercut banks. Also estimate the areas of instream vegetation (counts of vegetation divided by total substrate assessments, multiplied by total stream area assessed). Follow a similar procedure to estimate the total area of water >30 cm deep, and >60 cm deep. Use a bar chart to display the areas of these six different types of fish cover between the two stream sites.

5) Calculate a single flow discharge estimate (cubic meters per second) for each site by multiplying average stream (m) width by average current velocity (m/sec) by average water depth (m). REMEMBER TO CONVERT DEPTHS AND CURRENT VELOCITIES INTO METERS AND METERS/SEC BEFORE MULTIPLYING.

6) Use a contingency table analysis (http://www.physics.csbsju.edu/stats/contingency_NROW_NCOLUMN_form.html) to compare substrate composition between the two sites.

7) Summarize your data (means and standard deviations), substrate counts, and statistical analyses in one or more tables as required.

Equipment:
Meter tapes, meter sticks, current meter, rangefinder, waders!