THE CORRELATION OF ZOOPLANKTON & TOTAL PHOSPHOROUS
Brandon Call1, Kenton Montgomery 2 and Daniel J. Lundberg, Ph.D. 1
Department of Science, Technology and Mathematics,
Gallaudet University, 800 Florida Ave NE, Washington, DC 20002
2 Department of Natural Resources, Central Lakes College, 501 W College Dr, Brainerd, MN 56401
1
Introduction
The main goal of my internship was to find whether there is
a correlation between zooplankton and total phosphorus
levels in Brainerd, Minnesota area lakes. The purpose of
this research is to find a quicker and cost-effective way to
monitor the lakes’ health. Total phosphorus concentrations
are analyzed, because they are associated with nutrient
loading in lakes, such as runoff from the lakes’ watershed.
Determining total phosphorus concentrations are
determined by laboratory-based experiments, which can
become expensive when water samples are tested by
certified laboratories or by students in the laboratory with
instrumentation.
Why did we choose zooplankton as a possible alternative?
Zooplankton are readily accessible to everybody, easily
collected and counted with a microscope after samples are
splitted if necessary. Zooplankton also are very important
to the lake ecosystem, because they act as the keystone
species in the food chain, which will support the fish in
lakes.
Copepod, rotifer, cladoceran, and ostracods were the types
of zooplankton (Figures 1-4) counted in the laboratory at
Central Lakes College in Brainerd, MN.
Results
Conclusions
Pour points of all the sub-watersheds that drain into
Crow Wing Lake were identified by ArcGIS. Samples for
total phosphorus and zooplankton were collected near
these pour points, where the water depth was at least
10 feet, and at the deepest part of the lake (CW LA)
(Figure 5). As shown in Figure 6, zooplankton density
generally increased over time during the summer as the
trophic state increased.
A bivariate analysis of zooplankton density versus total
phosphorus was done at the end of the internship
(Figure 7). The correlation is small and the p-value is
not significant (p-value = 0.64). Analysis was done
using the CORREL function for the data and an online
calculator was used to find the p-value
(http://www.socscistatistics.com/pvalues/pearsondistri
bution.aspx)
According to the bivariate analysis of zooplankton versus
total phosphorus concentration (Figure 7), there is no
correlation. The sample size is very small; however, this
project will be continued for the next summer and beyond
on Crow Wing Lake and other Brainerd, MN area lakes. It
will be interesting to see whether there continues to be
zero or little correlation, or whether a correlation becomes
apparent.
Another suggestion would be to have a certified laboratory
analyze the total phosphorus concentrations to compare
with the values obtained by the interns in the laboratory—
to confirm that the total phosphorus concentrations are
accurate.
Figure 8: A zooplankton
pleading for mercy
Fiigure 9: Zooplankton being
analyzed under the microscope
Figure 5: Crow Wing Lake pour points where the samples were
collected
Figure 2:
Rotifer; the
smallest
group of
zooplankton
Figure 3:
Cladoceran;
has two
pairs of
long
feeding
arms
Figure 4:
Ostracod; has a
body
similar to
bivalves
10,000,000
Zooplankton Density (#/m3)
Figure 1:
Copepod; the
strongest and
fastest animal in
the world
relative to it is
body size
1,000,000
100,000
10,000
6/12/15
1,000
7/3/15
7/24/15
100
Figure 10: Interns collecting samples from the canoe
10
1
1M
Throughout the internship, I harvested zooplankton by
going out in the field with the use of three important tools:
the Zooplankton Net to gather these tiny creatures from
the water column, Containers to store the samples, and
Ethanol to preserve the zooplankton for tallying purposes.
In the lab, I have three other important tools to use to
assist me in the counting of the zooplankton: the Plankton
splitter which helps me divide the zooplankton into a
manageable quantity for counting, a Microscope to aid in
my observation, and an iPhone Counter app to keep track
of those thousands of tiny creatures under the microscope.
The zooplankton density was then
calculated by the formula shown below,
the estimated amount of zooplankton
per cubic meter
D=N* S
in the water column.
V
1M
CW 01
CW 02 CW 03 CW 04
Crow Wing Lake Sites
CW 05
CW 06
Figure 6: Graph of Crow Wing Lake pour point sites over time
Zooplankton density vs. Total Phosphorus (ppb)
References
http://crowwing.us/241/Water-Wetlands
http://www.dnr.state.mn.us/index.html
80
70
60
Total Phosphorus (ppb)
Materials/Methods
CW LA
50
Acknowledgements
y = 1.7696ln(x) + 5.4612
R² = 0.0239
40
30
20
10
0
0
2,000,000
4,000,000
6,000,000
Zooplankton Density (#/m3)
8,000,000
Figure 7: Bivariate analysis of Zooplankton and Total
Phosphorous
10,000,000
-Anonymous Donor through Gallaudet University
-Gordon Brown Fund, administered by the Gallaudet
University Career Center
--Dean Kuehn, Dean Hatfield, and Ms. LaDoucer, Central
Lakes College
-Tony Johnsen, ASL Interpreter
-Giovanna Vasquez for total phosphorus work and Jeromino
Ocampos for ArcGIS data, my fellow interns