by abandoned mine runoff and agricultural waste. Biological assessment of the stream has been carried on over the past 30 years and
the stream is commonly used for an introduction to stream assessment in the General Biology II lab. All equipment required for completing the lab activity is presented in Table 1.
The methods provided below are divided into three lab sessions, which
are expected to take three hours each. Lab 1 provides the background
for the use of macroinvertebrates and identification of macroinvertebrates using anatomical characteristics (see Figure 1 and Table 2).
Lab 2 isolates the DNA using the organisms identified in the first
session. Finally, Lab 3 amplifies the COI region of the DNA samples
collected and analyzes the PCR products using gel electrophoresis.
The first lab begins with a review of macroinvertebrate identifica-
tion and importance in stream ecology and toxicology. This section
should include classification of the organisms for the assessment of
stream quality and ecological niche occupied by the organisms
present in the stream (Table 2). The identification of the macroin-
vertebrates can be completed using macroinvertebrates that are col-
lected fresh from the stream or that have been collected previously
and preserved in ethanol. Either way, the goal of this portion of the
lab is to allow students to gain some experience in the traditional
taxonomic identification methods. The method outlined in the cur-
rent learning module is given in this manner because of the
arrangement of the current lab at St. Vincent College, where the
molecular genetics section of the lab occurs before the stream water
analysis, which necessitates the use of preserved samples. The stu-
dents should be instructed to photograph with a dissecting micro-
scope to aid in identification of macroinvertebrates by general
taxonomic features. The images will be used to allow the students
to share the characteristics of the insects for identification of the
taxonomy group. Images can be used by students in preparing a
report from the lab, assessing the students’ ability to properly iden-
tify the macroinvertebrates. For the identification, several published
keys are available to assist students, such as those from the Stroud
Figure 1. Sample images of common macroinvertebrates found in the streams of southwestern Pennsylvania, including the
stonefly, identifiable by the two long antenna-like tails; mayfly, identifiable by the three (in some species only two) long, antenna-like tails and feathery gills on the abdomen; midge larvae, identifiable by cylindrical, slightly curved, segmented bodies with
distinct head and prolegs; and caddisfly, identifiable by its curved body with abdominal gills and hooks at the dorsal end.