Macroinvertebrate Populations Lack Diversity Throughout Nahant Marsh Pond

1
Macroinvertebrate Populations Lack Diversity
Throughout Nahant Marsh Pond Jenna
Harper-Exercise Science, Samantha Themas-Biology,
Samantha Troyer-Psychology, Alex
Wirzbach-Psychology St. Ambrose University

• Background
• Benthic macroinvertebrates are small organisms
  that live on the floor of freshwater ponds or
  streams.
• The macroinvertebrate group includes organisms
  such as snails, worms, larvae, leeches, etc.
• The diversity of macroinvertebrates determines
  the overall integrity of a water source.
• Different types of macroinvertebrates indicate
  the quality of the water.

Figure 1 Map of Nahant Marsh Pond
This map includes the labeled locations where our
eight samples were taken. The locations were
predetermined by another research group

Hypothesis There will be unequal amounts of
different types of macroinvertebrates through out
various locations in the pond.

Figure 2 Dipnet Technique
Results To determine the significance of the
differences in number of macroinvertebrates per
location, we conducted an analysis of variance
test (ANOVA) with the data collected over the
three week period. After analyzing the numbers
produced by the test, we determined that there
were significant differences between the total
number of macroinvertebrates between each
plot. To determine the diversity of each plot,
we ran a Chi Squared test with the total number
of different species at each plot. The test
results showed an insignificant difference in the
number of different species at each location.
Figure 2 is a visible representation of the
dipnet technique. To perform the dipnet
technique we inserted the dip net into the pond
until the far rim of the net reached the floor of
the pond. We swept the net across the top of the
floor of the pond the length of the marked 90
centimeters. After we made the sweep, we held
the rim of the net above water and carefully
moved the submerged net back and forth to filter
excess mud.
These are examples of macroinvertebrates that we
found, and the type of water quality group they
thrive in.
Methods We took macroinvertebrate samples at
eight different locations within the pond at
Nahant Marsh (Figure 1) We used the dipnet
technique to collect samples (Figure 2) We placed
the samples in labeled Ziploc bags We searched
the samples and identified the macroinvertebrates
by color and structure the following morning We
counted the number of each type of
macroinvertebrate at all eight locations and
placed the numbers in a data table We repeated
this process three times over a period of three
weeks To determine if the differences between the
total number of macroinverebrates at each
location were significant, we produced an ANOVA
summary with the averages of the data we
collected over the three days To further analyze
our data, we ran a Chi Squared test on the total
number of species at each location to determine
if there was a significant difference in the
diversity at each location


Conclusions We partially support our hypothesis
on behalf of the Analysis of Variance because the
results of this test show significant differences
between the total number of macroinverebrates at
each location. We partially reject our hypothesis
because the Chi Squared test shows that there is
no significant difference in the number of types
of macroinvertebretes (diversity) between the
locations. Acknowledgments We would like to
thank Dr. Richard Legg, Dr. Shannon Mackey, Dr.
Mathew Halfhill, Dr. Paul Koch and the entire
staff at Nahant Marsh for their incredible help
and support. References City of Federal Way.
(2004, September). Macroinvertebrate Sampling.
Retrieved September 12, 2008, from
http//www.cityoffederalway.com/Page.aspx?page58
0 Clallam Country Washington. (2008). Field
Procedure Benthic Macroinvertebrate Sampling
Retrieved September 12, 2008, from
http//www.clallam.net/streamkeepers/assets/applet
s/Benthic.pdf Helgen, J (2000). Wetland Health
Evaluation Program. Macroinvertebrate sampling
protocols. Retrieved September 8, 2008, from
http//www.mnwhep.org/id66.html IOWATER. (2005,
March). IOWATER BENTHIC MACROINVERTEBRATE KEY.
Retrieved September 9, 2008, from
http//www.iowater.net/datashts/Level1BenthicKey05
.pdf