Aquatic Ecology Lab Exercise 6
Stream Environments
In this lab we will conduct several simple analyses of stream habitats. These analyses will be
based on the US EPA’s Rapid Bioassessment Protocol (RBP). There is a CA RBP that is
derived from the Federal RBP, however, it is much less extensive than the EPA version. Next
week we will visit the same site to sample stream biota, primarily focusing on
macroinvertebrates. The rationale for sampling the same site is to first gain familiarity and
understanding of a particular habitat in order for you to understand why this habitat is able
to support the biota we will examine in the second week.
There are FOUR main tasks for this week. The descriptions below are simplified from the
more complete explanations of tasks on subsequent pages and as we will have discussed in
class. You will have to carefully designate tasks among group members to increase efficiency!
TO DO:
-By the time we depart the site, each group must complete the following:
1. ‘Habitat Assessment Field Data Sheet’ and calculated score
2. ‘Stream Habitat Characterization’
3. Substratum Composition (on back of field data sheet)
4. Collect macroinvertebrate samples
-----------------------------------------------------------------------------------------------------------------I. Comparison of Habitat Assessment (HA) Scores
Calculate (sum) your HA Score. We will compare among groups.
Questions: (you may need to refer to):
HTTP://WWW.EPA.GOV/OWOW/MONITORING/RBP/CH05B.HTML#SECTION 5.3
A. What variables (categories) did you feel were most subjective?
B. Do you think the variables should carry equal weight towards habitat
assessment?
C. What would you do if were conducting a study of stream habitats and found
that the physical habitat looked optimal, but there were few species and low
numbers of macroinvertebrates in the stream? How would you proceed to
examine this discrepancy in more detail?
III. Discharge Calculations
Calculate discharge for your group’s riffle. (We will compare discharge estimates
among groups)
Questions:
A. How ‘even’ was the stream velocity across the wetted width? Did this
correspond to changes in depth?
B. Do you expect the actual discharge to vary between segments (riffle-pool) and
reaches (upstream-downstream)? Why or why not (e.g. what factors may
influcence differences in discharge among the adjacent reaches)?
Group Members:_____________________________________________________________
II. Substrate Composition Quantification
(SEE FIELD DATA SHEET) Quantify substrate composition in your riffle (and pool
if possible). Assign larger particles a higher score, producing a range of
5=Boulders, to 1=Sand and Silt. Produce an average score for your riffle and pool.
Questions:
A. Did you find the expected differences in riffle and pool substrate composition?
B. Were there clear delineations in riffles and pools which corresponded to
substrate composition with water depth and velocity?
IV.
Macroinvertebrate samples
Collect, sort, label, and preserve your macroinvertebrate samples
Next week’s lab will be dedicated to:
1. Working with your macroinvertebrate samples
2. Relating these assemblages to habitat variables
Assignment:
Get approval on all completed data sheets as you complete each procedure. I will collect
your compiled data sheets and make copies available for everyone in your group (be sure
to include the names of each person in the group). Turn in your answers to the questions
above when we next meet for lab on April 21.