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HYPOTHESIS
The effect of temperature over macroinvertebrate abundance of two streams in
San Juan, Puerto Rico Stephanie M. Rivera Morales¹, Jorge Rosario Vega1, Prof. Frank G. Torres Vélez, B.S.¹
1University Gardens High School, San Juan, P.R.
RESULTS
[1] Byers, H. (2005). Phosphorus, Sediment and Escherichia coli Loads in Unfenced Streams of the
Georgia Piedmont, USA. Journal of Environmental Quality, 34, 2293-2300.
[2] Corsi, S. (0). Unit-Area Loads of Suspended Sediment, Suspended Solids, and Total Phosphorus
from Small Watersheds in Wisconsin. USGS: Fact Sheet, ., ..
[3] Durance, I. (2007). Climate change effects on upland stream macroinvertebrates over a 25-year
period. Global Change Biology, 13, 942-957.
[4] Figueroa, R. (0). Macroinvertebrados bentonicos como indicadores de calidad de agua. VI
Jornadas del Conaphi-Chile, ., 1-24.
[5] Heathwaite, A. (1996). Contribution of Nitrogen Species and Phosphorus Fractions to Stream
Water Quality in Agricultural Catchments. Hydrological Processes, 10, 971-983.
[6] Johnson, L. (1997). Landscape influences on water chemistry in Midwestern stream ecosystems.
Freshwater Biology, 37, 193-208.
[7] Mallin, M. (1999). Hurricane Effects on Water Quality and Benthos in the Cape Fear Watershed:
Natural and Anthropogenic Impacts. Ecological Applications, 9(1), 350-362.
[8] Oscoz, J. (2006). Variación de la comunidad de macroinvertebrados bentónicos en relación con la
calidad de las aguas. Limnetica, 3, 683-692.
[9] Packman, J. (1999). Using turbidity to determine total suspended solids in urbanizing streams in
the Puget Lowlands. Confronting Uncertainty: Managing Change in Water Resaources and the
Environment, 27-29, 158-165.
[10] Pérez, G. R. (1999). Los macroinvertebrados y su valor como indicadores de la calidad del
agua. Academia Colombiana de Ciencia, 23(88), 375-387.
REFERENCES
The results obtained through qualitative and quantitative analysis of the data support the
original hypothesis that temperature would affect the urban stream more than the rural stream and
macroinvertebrate richness would reflect the impact. Water temperature, mean macroinvertebrate
density, and mean macroinvertebrate richness from the urban stream were all modeled with
polynomial regressions while these same data from the rural stream were modeled with linear
regressions. This demonstrated that variability in the water temperature from the urban stream
reflected itself as variability on the macroinvertebrate data. Meanwhile, constancy in the rural
stream’s water temperature reflected itself as constancy in the macroinvertebrate data. TP, TSS and
pH results have a strong additional impact upon the macroinvertebrate community in both streams
and should therefore be considered when analyzing the variability in their density and richness.
Nevertheless, these results were in occasions similar in both streams but yet there was variability in
the macroinvertebrate analysis.
These findings demonstrate the negative effect of temperature over stream ecosystems and
therefore remind of the necessity of decreasing the rate of human-driven temperature rises (e.g.
“global warming”) to prevent the unwanted alteration of aquatic habitats.
Macroinvertebrate abundance in the urban stream will be more affected by temperature than the
one in the rural stream. Macroinvertebrates will have different tolerances to these differences in
temperature, and their richness will reflect the impact of temperature upon the stream.
Two streams were chosen, one with an urban catchment area (Señorial Stream or
PN_SenStrm_49) and one with a rural catchment area (Rivera Stream or PN_RivStrm_154). The
experimentation was done from December 2010 through February 2011 and consisted of weekly
water quality samplings, temperature and pH level measurements; in addition to
macroinvertebrate samplings done every three weeks. A reach was determined, facing upstream,
for each stream (28m for PN_RivStrm_154 and 40.7m for PN_SenStrm_49) in order to conduct all
samplings.
Water quality samples for each stream were taken weekly by filling three replicates of Total
Phosphorus (TP) and three replicates of Total Suspended Solids (TSS) with water from the
beginning of each reach. In addition to these, temperature and pH levels were measured with a
Milwaukee® pH52 pH/temperature meter.
Macroinvertebrate samplings were conducted every three weeks at three different riffles of
each stream. Ascending from downstream, each determined riffle was disturbed during thirty (30)
seconds while holding a kick net in front to capture all organisms. These were then preserved in
Whirl-pak® bags with 95% ethanol.
After all fieldwork, water quality samples were sent in refrigerated containers to the
University of Vermont Water Quality Laboratory [1] for their analysis. Macroinvertebrate samples
were counted and identified with the “Guide to Aquatic Invertebrates of the Upper Midwest” [2]
and the calculation of metrics was done to obtain measurements of richness, density, and values
for the Hilsenhoff Biotic Index.
All data were subject to a statistical analysis consisting of calculation of means, standard
deviations of data sets, and 95% confidence intervals were calculated to establish statistical
significance between values.
_____________________________________________________________________________
[1] The method for the determination of total suspended solids (TSS) and total phosphorus (TP)
was determined from Standard Methods for the Examination of Water & Wastewater (APHA 2005)
and Wetzel & Likens 2000.
[2] Bouchard, R. W. (2004). Guide to Aquatic Invertebrates of the Upper Midwest. St. Paul:
University of Minnesota.
VT EPSCoR Streams Project
Dr. Declan McCabe and his laboratory staff at St. Michael’s College, Burlington, VT
Dr. Juan Arratia, Mrs. Wanda Rodríguez and the staff of AGMUS-Student Research
Development Center of the Universidad Metropolitanta (UMET), San Juan, P.R.
University of Vermont Water Quality Laboratory
ACKNOWLEDGEMENTS
CONCLUSION
Streams have a great importance in the development and maintenance of different
ecosystems, and serve as habitats for many aquatic animal, and plant, species. Although it is
believed that temperature is an indicator of the macroinvertebrate abundance of a stream, there
are not sufficient studies to sustain it. To prove the relationship between temperature and
macroinvertebrate abundance, Total Phosphorus (TP), Total Suspended Solids (TSS), pH levels,
water temperature, and macroinvertebrate abundance and richness were measured in two
streams with different catchment areas (rural and urban). It is expected that macroinvertebrate
abundance in the urban stream will be more affected by temperature than the one in the
rural stream; and that macroinvertebrates will have different tolerances to these differences in
temperature, and their richness will reflect the impact of temperature upon the stream.
This study will allow a better understanding of the consequences that temperature raises
will have over stream ecosystems in the next years. Stream ecosystems are an important source
of food in the lower trophic levels and any change in these will have repercussions in the higher
levels thus affecting human beings. Hence it is important to understand the behavior of stream
ecosystems towards stressing factors as temperature.
METHODOLOGY
R² = 0.3171
R² = 0.4131
0
100
200
300
400
500
600
700
0 5 10 15 20 25 30 35 40
Tota
l Ph
osp
ho
rus
(µg/
L)
Sample number(n=33)
TP Data
PN_RivStrm_154 PN_SenStrm_49
0
50
100
150
200
250
300
350
TP v
alu
e
(n=33)p<0.05
Mean TP
PN_RivStrm_154 PN_SenStrm_49
R² = 0.8036R² = 0.3253
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30 35
Tota
l Su
spe
nd
ed
So
lids
(mg/
L)
Sample number(n=33)
TSS Data
PN_RivStrm_154 PN_SenStrm_49
0
2
4
6
8
10
12
14
16
18
TSS
valu
e (
mg/
L)
(n=33)p<0.05
Mean TSS
PN_RivStrm_154 PN_SenStrm_49
R² = 0.0946
R² = 0.9099
20
21
22
23
24
25
26
27
28
29
#1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11
De
gre
es
°C
Sample
Water Temperature
PN_RivStrm_154
PN_SenStrm_49
00.5
11.5
22.5
33.5
44.5
55.5
66.5
77.5
88.5
9
#1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11
pH
val
ue
Sample
pH Levels
PN_RivStrm_154
PN_SenStrm_49
R² = 0.6094
R² = 1
-200
0
200
400
600
800
1000
#1 #2 #3 #4
De
nsi
ty (
anim
als/
sam
ple
)
Macroinvertebrate Sample
Mean Macroinvertebrate Density
PN_RivStrm_154
PN_SenStrm_49
6.036.07
5.99 6.09
5.666.03
7.95
6.88
R² = 1
0
1
2
3
4
5
6
7
8
9
#1 #2 #3 #4
Bio
tic
Ind
ex
Val
ue
Macroinvertebrate Sample
Hilsenhoff Biotic Index
PN_RivStrm_154
PN_SenStrm_49
Water quality laboratory results reflect a statistically significant (P<0.05) difference between
both streams in both tests (TP and TSS). pH levels were similar between both streams and
temperature was found to be constantly higher in PN_SenStrm_49 than in PN_RivStrm_154.
Macroinvertebrate abundance was higher in PN_SenStrm_49 with a total of organisms equal
to 983; compared with 552 from PN_RivStrm_154. Nevertheless, there was a difference between both
streams in macroinvertebrate density and richness. PN_RivStrm_154 had positive linear regressions
in both measurements thus demonstrating increasing variability and quantity.
PN_SenStrm_49 macroinvertebrate order/families were those with high tolerance to levels.
This is reflected by the high amount of D. chironomidae found in all samples, specially the third one. It
is worth mentioning that the third sample chironomids were red when taken, indicating low dissolved
oxygen levels in the water.
By analyzing the regressions for temperature and macroinvertebrate density and richness data
sets it may be observed that variability of temperature in PN_SenStrm_49 was proportional to
variability in richness and density. On the other hand, constancy of temperature in PN_RivStrm_154
was proportional to constancy in richness and density.
R² = 0.8
R² = 1
0
1
2
3
4
5
6
7
8
9
10
#1 #2 #3 #4
fam
ilie
s p
er
sam
ple
Macroinvertebrate Sample
Mean Macroinvertebrate Richness
PN_RivStrm_154
PN_SenStrm_49
INTRODUCTION
