Stream Ecology
Stream Quality Assessment Exercises
A good way to analyze the environmental quality of a stream is via a combination of
water chemistry analysis, physical habitat assessment, and characterization of the benthic
macroinvertebrate community. A physicochemical approach provides a “snapshot” of
current habitat and water quality conditions, but using macroinvertebrates to assess water
quality provides a “moving picture” of the recent past.
You are familiar with the types of chemical and physical habitat measures that can be
performed on streams (e.g., DO, pH, alkalinity, width, discharge, temperature, substrate,
bank stability, canopy, etc.), and with techniques for sampling benthic invertebrates (with
a D-net or Surber sampler). You are also familiar with various schemes that classify
benthic macroinvertebrates into groups based on their tolerance to pollution (such as that
in the NRCS’ Stream Visual Assessment Protocol, Iowa’s Iowater program, or Auburn
University’s Bio-Assess).
For Field & Lab Exercise #7 (20 points), we will examine the macroinvertebrate (Surber)
samples we took from the Cottonwood River earlier this semester and use Auburn’s BioAssess and invertebrate tolerance scores to develop a cumulative index value that will
allow us to assess quality of that river.
For Field & Lab Exercise #8 (40 points), we will examine a subset of those data to
analyze percent EPT at our site (see, for example, Tiemann et al. 2005. Effects of
lowhead dams on the ephemeropterans, plecopterans, and trichopterans group in a North
American river. Journal of Freshwater Ecology 20:519-525).
We will process our macroinvertebrate samples in the laboratory. Each of 3 research
teams (Yellow, White, or Blue) will be responsible for processing and identifying 1 jar
from each of our 2 habitats. Begin by sorting the macroinvertebrates into groups of
similar-looking organisms, then use keys and identification guides to identify individuals
to the level indicated on the Bio-Assess Picture Key. Count the number of individuals in
each of the 17 taxa belonging to the 3 Macroinvertebrate Groups on the Bio-Assess
handout (that is, do not simply assign a letter code for the tally). Keep data from all 6
samples separate!
For Field & Lab Exercise #7, due __________________, pool data from the 6 jars to
facilitate your stream quality assessment by completing the Bio-Assess form, indicating
the appropriate letter code (R, C, or A) for each taxon. Hand-in the completed BioAssess form.
For Field & Lab Exercise #8, due __________________, calculate % EPT in each of the
6 samples and test your null hypothesis statistically. Hand-in a brief but thorough (ca. 2page, word-processed) synopsis of your hypothesis, data, statistics, and conclusion.