Lab 8
Stream Ecology Using ANOVA
April 10, 2002
Group 5
Abstract
Stream ecology was analyzed in this lab because it indicates the effects of pollutants on
organisms in the environment. Lab 8 compared the mouth and base of Huron Creek,
which has been affected by paved-over wetlands and road salts to Coles Creek, which is
virtually untouched by construction. The Total Dissolved Solids (TDS), temperature,
and amount and type of organisms in the two streams were measured as indicators of the
health of the stream. The conductivity, a measure of TDS, and temperature were
collected using a computer program “Test 12 Total Dissolved Solids”. The amount and
types of macroinvertebrates were determined by collecting 10 rocks from the stream.
The organisms on the rocks were then counted and identified on each rock. This
technique was used as a biological indicator of the health of the two creeks. Cole’s Creek
was found to be ecologically healthier than Huron Creek through analyses of aquatic
organisms present and of the conductivity of the water. Additionally, ANOVAs
performed on the data showed Cole’s Creek to be statistically different from Huron Creek
in temperature, conductivity, and organism diversity. Good. Some more specific results
would be appropriate (e.g., The conductivity at Coles Creek (65 μS) was low and
unaffected by road salts in comparison to the conductivities measured in Huron Creek
(112, 490 μS). Both the number of individuals (avg. 35 per rock) and the variety of types
(18 organism types identified) found in Coles Creek were much higher than those found
in Huron Creek (5 and 7 per rock, 5-7 organism types)./
Introduction
One aspect of Environmental Engineering deals with measuring pollution concentrations
and controlling pollution in the environment. The reason for doing this is to protect the
organisms present within those environments. Some species of organisms are more
susceptible to pollution than others. Those species indicate the health of the ecosystem.
Organisms play important roles in their ecosystem; therefore, it is critical to monitor their
status to safeguard the health of the environment
The objective of the lab was to observe the effects of paved over wetlands, and road salt
on stream ecology. By measuring the temperature, conductivity, and the
macroinvertebrates in an unhealthy stream compared to a healthy stream, one can see the
effects of pollutants on stream ecology. A large area and large number of organisms
were sampled. Therefore, ANOVAs were used to assess if any of the data was/were/
statistically different from one site to the next site.
The areas sampled were from the mouth and the base of Huron Creek and from Cole’s
Creek. Huron Creek starts from behind Wal-Mart and goes to the waterfront park on the
Portage Canal. The paving of wetlands there has altered the stream’s original course and
there is less flow upstream than compared to/use either “than at” or “compared to”/ the
mouth. Cole’s Creek is virtually untouched by human impacts, and is fast flowing
compared to Huron Creek.
Methods
Each Lab section sampled either Huron Creek or Cole’s Creek. Each group collected 30
TDS measurements, 30 temperature measurements, and collected ten rocks from the
respective streams. The rocks where then placed in plastic bags and taken to the lab for
counting and identifying of organisms. Both the conductivity and temperature
measurements were taken using the Mac laptop computers to collect the data. Since
conductivity depends on the total number of ions present in the water, conductivity and
TDS are linearly related. So, from the conductivity measurements, TDS concentrations
were determined. The steps outlined in Lab 8 handout (Urban 2002) were followed.
However, conductivity and temperature measurements were taken at three different
locations on Huron Creek instead of two different locations.
Results
Table 1 below illustrates the TDS levels, measured by conductivity, for the four different
test sites. Huron Creek at Wal-mart exhibited the highest TDS concentrations of 492.04
(Significant digits 490) mg/L while Cole’s Creek had the lowest TDS concentrations of
66.87 mg/L. The data suggested that TDS concentrations increased in Huron Creek as it
passed by Wal-mart and then slowly decreased as the Creek drained to the Portage Canal.
Road salt and other dissolved ions associated with the chemicals surrounding Wal-mart
have been the major factor in this phenomenon.
Table 1: Statistical Summary for Conductivity/TDS (mg/L)
Cole's Creek
Huron Creek Mouth
Mean
66.87
346.0
St Dev
1.40
164.6
COV
0.02
0.48
Huron Creek Walmart
492.04
12.05
0.02
Huron Creek Walmart before
112.68
1.99
0.02
Significant digits
Table 2: Biosurvey Results
Cole's Creek Averages
Midge
32.1
Stonefly
0.3
caddisfly
2.5
blackfly
0.4
Mayfly
0.3
copepod
0.0
leech
0.2
Snail
0.1
Watersnipe
0.1
sowbug
0.0
Scud
0.1
worm
0.1
dragonfly
0.1
crane fly
0.1
Cacoon
0.2
Other
1.2
Huron Creek Walmart Averages
blackfly
1.5
midge
3.9
caddisfly
0.2
riffle beetle
0.0
worm
0.1
mite
0.0
dragonfly
0.1
Other
0.3
Huron Creek Mouth Averages
caddisfly
midge
worm
blackfly
mite
Other
1.1
6.0
0.0
0.0
0.1
0.1
Table 2 shows the average number of macroinvertebrates per rock for each test site.
Cole’s Creek contained the highest number of organisms per rock. Huron Creek had a
relatively low number of organisms at both locations. The category named “Other”
summed all of the individual organisms not bolded /There is no such verb./ in the table.
Tables 3, 4, and 5 below show the results of the ANOVA for temperature, conductivity,
and number of organisms for each of the four sites. The F value was larger than the Fcritical value for all three cases. This meant that all four sites are statistically different
from one another in all three cases. /No. Be careful of your wording. The ANOVA
results indicate that not all four sites are similar, but it does not indicate whether one is
different from the others, whether two are different from another two, or whether each
one is different from the others./
Table 3: ANOVA for Temperature
Groups
Count
Cole's Creek
93
Huron Creek Mouth
31
Huron Creek Walmart
30
Huron Creek
Walmart Before
30
ANOVA
SS
Source of Variation
Between Groups
148.338261
Within Groups
1.19555149
Total
149.533812
Table 4: ANOVA for Conductiviy
Groups
Count
Cole's Creek
122
Huron Creek Mouth
119
Huron Creek Walmart
60
Huron Creek
Walmart Before
30
ANOVA
SS
Source of Variation
Between Groups
9267765
Within Groups
3205647
Total
12473412
Sum
Average Variance
242.1303 2.603551 0.011514
63.98874 2.064153 0.000272
17.16394 0.572131 0.000801
18.70352 0.623451 0.003616
df
MS
F
P-value
F crit
3 49.44609 7444.511 1.9E-188 2.654794
180 0.006642
183
Sum
Average Variance
8157.719 66.86655 1.948282
41171.19 345.9764 27090.94
29522.53 492.0422 145.1844
3380.318 112.6773 3.969625
df
MS
F
P-value
F crit
3 3089255 315.1271 4.17E-96 2.632227
327 9803.203
330
There are not all the observations being read; therefore, the values are slightly off.
Table 5: ANOVA for Organisms
Groups
Count
Cole's Creek
40
Huron Creek Mouth
40
Huron Creek Walmart
40
ANOVA
SS
df
Source of Variation
Between Groups
23128.02
Within Groups
18686.35
Total
41814.37
Sum
1436
287
231
Average
35.9
7.175
5.775
Variance
363.2718
82.40449
33.4609
MS
F
P-value
F crit
2 11564.01 72.4052 3.44E-21 3.073765
117 159.7124
119
Discussion
Figures 1,2, and 3 show the distribution of aquatic macroinvertebrates in Cole’s and
Huron Creek. Midges were most predominating/predominant/ in all three sites. Cole’s
Creek displayed a wider variety in/of/ organisms than did either test site on Huron Creek,
which displayed a lower variety of organisms at higher population levels percentagewise. Huron Creek also had a larger percentage of group 2 and 3 taxa organisms, which
are more pollution tolerant, than did Cole’s Creek. Cole’s Creek contained more group 1
taxa organisms, which can only be found in good quality water. This indicated poorer
water quality in Huron Creek than in Cole’s Creek. This difference may have been due
to Huron Creek flowing through more industrialized areas and encountering more
pollutants than Cole’s Creek.
Huron Creek Walmart Macroinvertebrates
blackfly
midge
caddisfly
Other
Figure 1: Huron Creek at Walmart Macroinvertebrate Pie Chart How could the reader tell what
is the percentage of each type of organism from the figure?
Cole's Creek Macroinvertebrates
Midge
Stonefly
caddisfly
blackfly
Other
Figure 2:Cole's Creek Macroinvertebrate Pie Chart
Huron Cree k Mouth Macroinve rte brates
caddisfly
midge
Other
Figure 3: Huron Creek at Mouth Macroinvertebrate Pie Chart
Temperature also may have played a role in the number of organisms per rock. The data
indicated that higher temperatures correlated /You should say this only if you performed
a correlation analysis and found a significant correlation coefficient./ with an increased
variety of organisms. Cole’s Creek had an average temperature of 2.6 oC and had a wide
variety of organisms. On the other hand, Huron Creek at Walmart had an average
temperature of 0.57 oC and had a low variety of organisms.
Conductivity, as a measure of TDS concentrations, also may have played a role in the
number of organisms per rock. As shown in Table 1, Cole’s Creek had a much lower
average conductivity level at 66.87 mg/L than did any of the points on Huron Creek,
which ranged from 112.68 mg/L to 346.0 mg/L (significant digits?). It was not
determined exactly how much of the conductivity levels were due to saline runoff from
streets but it can be assumed that road salt accounted for a large part of the high
conductivity concentrations seen in Huron Creek.
All three ANOVAs performed on temperature, conductivity, and number of organisms
showed statistical differences between the four test sites. This was justified in that the
averages of temperature, conductivity, and number of organisms for each site were
noticeably different from one another. The ANOVAs confirmed this through statistical
analysis. Therefore, not only was Cole’s Creek different from Huron Creek in all three
categories, but Huron Creek displayed different characteristics within the stream itself at
the three different points that were measured. /You should have performed t-tests to
determine which site was different from the others./
Conclusion
In conclusion, Cole’s Creek appeared to be of higher water quality than Huron Creek
according to conductivity concentrations and macroinvertebrate diversity. The
ANOVAs that were performed in this lab also showed that Cole’s Creek is statistically
different in all three measured categories from Huron Creek. In addition, Huron Creek
displayed statistical differences in all three measured categories at different points within
itself due to the areas it flows past and the alteration of its original pathway. This lab
confirmed that the virtually pristine Cole’s Creek was of better water quality than
Huron’s Creek, which has been subjected to the construction associated with Wal-mart
and pollution sources from Houghton’s urban areas. Good
Sample Calculations
n
1. Mean- X =
∑X
i =1
i
N
sample: (13.9+13.2+13.7)/3=13.6
n
σ =
2. Standard Deviation-
∑(X
i =1
i
− X )2
N −1
sample: (((13.9-13.6)2+(13.2-13.6)2+(13.7-13.6)2/(3-1))^(1/2) = 0.4
COV =
3. Coefficient of Variance -
σ
X
185.7
185.7
= 0.196
= 0.196
945.6
945.6
Sample:
4. ANOVA-
∑ n (Y
k
Sb 2 =
j
j =1
−Y )
2
k −1
nj
Sj = ∑
2
(X
ij
−Xj)
2
n j −1
i =1
k
Sw2 =
j
∑ (n
j =1
j
− 1) S j 2
k
∑ (n
j =1
j
− 1)
Sb 2
F= 2
Sw
Fcrit is found in Table 8.2 in Statistical Procedures for Analysis of Environmental
Monitoring Data and Risk Assessment
WORKS CITED
Urban, Noel. “Week 8-Stream Ecology and ANOVA”. CE3502. Environmental
Monitoring, Measurements & Data Analysis. 2002.
McBean, Edward A., Rovers, Frank A.. “Characterizing Coincident Behavior-Regression
and Correlation”. Statistical Procedures For Analysis of Environmental
Monitoring Data & Risk Assessment. New Jersey: Prentice Hall PTR. 1998. p
139.
CE3502
Laboratory Report Evaluation Sheet
I.
Title Section
3/3
1) Title 1) Date 1) Authors
II.
Abstract
6/7 Needs more specific results
2) Objective / Purpose 1) Methods 2) Key results 2) Significance
III.
IV.
Introduction
a) Concern with this topic (background)
b) Objectives
4/4
4/4
Apparatus and Procedure
4/4
1) Reference lab handout 1) Changes made to lab
V.
Results
12/15
5/5) Text along with results. Significant digits
VI.
Discussion
14/17
Overall, the discussion is quite good. The ANOVA results are over-interpreted and no t-tests were
performed to identify the specific differences.
VII.
Conclusion and Recommendations
9/9
2) Answer the objectives 3) Main Results 2) Sources of Errors 2) Assumptions
VIII.
Tables, Figures, Appendices
8/10
2/2) Label Appendices A, B, etc. 2/2) Number and Title Tables 2/2) Number and Title Figures 2/2) Units 0/2) Label Axis
IX.
Composition
17/20
1/2) Spelling 4/5) Grammar 2/2) Separate paragraphs / single sentence paragraphs 2/2)
Sample Calculation 4/5) Meaning behind writing 4) Not concise writing
X.
Overall Appearance, Organization
8/8
2) Ease of finding data (including summary tables) 2) Neatness of tables / figures 2) Neatness of sample calculation
2) Neatness of report format
Name of Student:
Total Points for Report (100 Maximum):89/90
Comments: A very nice report except for lacking t-tests.