0
Spring
The effects of nitrogen on the growth
rate of Salvinia minima
Dominic Galanti
BIOL 220M
Pennsylvania State University
TA: Andrew Fister
Due: April 21, 2014
[Type the company address]
14
[Type text]
[Type text]
Galanti, 1
Introduction
With an increase in water pollutants human populous is often to blame for
impure water throughout the world. The pollutants range from large solid masses of
plastic to heavy metals and high levels of nitrates1. These come from common
littering, which follows waterways that lead from streams to the ocean. Inevitably
this affects all levels of the food chain. Many factories and sewage treatment plants
are held to low standards and end up dumping large quantities into local water
systems. In addition to this fertilizer runoff effectively raises nitrogen and
phosphorus levels in the water, key nutrients for plant growth, which causes algal
blooms in the water. These algal blooms can kill or weaken fauna and outcompete
other flora2. In order to rectify waterway contaminants environmentalists
incorporate phytoremediation into their work. Throughout these experiments
scientists used different variables to determine growth rates in Lemna minor and
Salvinia minima with a comparison to the factors found in polluted bodies of water3.
Among all of the factors found in a real life scenario these experiments investigated
the growth rates in increased ratios of either phosphorus or nitrogen along with
competition between the two species. This experiment will take a primary focus on
the phytoremediation abilities of Salvinia.minima and it’s growth rate in water with
higher than normal nitrogen levels.
Studies suggest that certain plant species uptake varying levels of nutrients
as well as enduring with different fitness levels4. Through investigation of the fitness
of Salvinia minima in nutrient levels equivalent to their typical growing
[Type text]
[Type text]
Galanti, 2
environment and nutrient levels representative of waters with higher nutrient
levels due to pollution, environmentalists will have a better understanding of
Salvinia minima fitness in polluted waters and it’s applications in
phytoremediation4. Due to Salvinia minima’s range of environmental tolerance it can
be predicted that with an increase in the available nitrogen Salvinia will have a
higher growth rate and carrying capacity.
Materials and Methods1
This experiment took place over a matter of 5 weeks. The first week was
focused on preparing the cultures. To set up there were 5 dishes; two to act as
controls for growth with an artificial pond water media, one with 12 individuals and
the other with 24 individuals of the species Salvinia minima. The dish with 24
individuals was considered the control for the nitrogen growth experiment. The
remaining 3 dishes contained 24 individuals of Salvinia minima with water from the
same source as the control but an additional 2 ml CaNo3 per dish. Each dish
contained 10 oz. of water. When preparing dishes the quantity of Salvinia minima
reflects the number of individuals, or each leaf set with a stem, not the number of
leaves.
On the Monday of each week an additional 2ml of CaNo3 was added per dish.
In addition the dishes were watered 3 days of the week along with 2 days where the
cultures were counted for thalli, number of leaves.
Within the growing environment, a greenhouse at the Pennsylvania State
University during March 2014 existed two species, Lemna minor and Salvania
[Type text]
[Type text]
Galanti, 3
minima. These two species existed in separate containers for this experiment but
were in the same greenhouse. The additional species, Lemna minor was used in
other bioremediation experiments and could be used as a comparison to Salvinia
minima in future experiments. The plants were not shaded and the daytime
temperature within the greenhouse was set to 70 degrees although varying sunlight
intensity could affect the surface temperature as this experiment was done in
March.
In addition to this particular experiment scientists combined data from
similar bioremediation experiments to better understand each scientist’s specific
experiment. The additional experiments included an identical experiment to this
specific nitrogen growth variable with the substitution of phosphorus for nitrogen.
The other experiments followed the two stated above substituting Lemna minor for
Salvinia minima. The last experiment investigated the competition between the two
species (Lemna minor and Salvinia minima). Unlike the nutrient experiments, which
used the 24 individual dish as a control, the competition used the 12 individual dish
as a control to compare to because the initial setup of these dishes included 12
individuals of each Lemna minor and Salvinia minima.
Equations:
Geometric rate of increase: λ=(Nt+1)/(Nt)=ermax
Logistic Growth Equation: dN/dt=rmaxN[(k-N)/N]
Lamda vs. N: y = -0.0231x + 6.6299
Surface Area Carrying Capacity Estimation: S.A.dish/S.A.thalli
[Type text]
[Type text]
Galanti, 4
The above equations were used to determine growth rates, carrying
capacities, and to generate the below models for the results. .
Results
Table 1: Growth of Salvinia Control
Experiment 1-24 Salvinia Control
Time (weeks)
Number of Leaves
0
52
2
142
3
138
4
319
Table 1 is a collection of thalli counts of the control experiment over a 5-week
period.
Table 2: Growth of Salvinia with Nitrogen
Experiment 2-24 Salvinia with Nitrogen
Time (weeks)
Number of Leaves
0
53
2
158
3
225.33
4
335
Table 2 shows the average number of leaves in three cultures of Salvininia minima
with an increased nitrogen level per week.
Table 3:
Additional calculated values for the growth of Salvinia minima
Time (weeks)
Lambda
Ln(N)
Carrying
Capacity(k)
[Type text]
[Type text]
Galanti, 5
0
N/A
3.97
K by graph: 243.71
2
2.98
5.06
K by S.A.: 207.46
3
1.42
5.41
4
1.48
5.81
Table 3 shows growth values calculated given the leaf counts and population
equations stated previously.
Table 4: Final counts from other group experiments
Group
1-12
1-24
1
2
3
Exp.
Phytofighters 153
190
229
219
240
S+P
Em’s Lems
326L
398L
54L 116S 42L 105L 76L 122S Comp
CSLSACD
510
290
417
345
386
L+N
When Life
198
623
916
962
998
L+P
gives you
Lemna
Table 4 shows data collected from groups conducting like experiments in the fourth
week of experiment.
Figure 1:Scatterplot of Control Experiment of N vs. t
Experiment 1: Control Salvinia-24
350
300
250
Experiment 1: Control
Salvinia-24
200
150
Expon. (Experiment 1:
Control Salvinia-24)
100
50
0
0
1
2
3
4
5
Figure 1 shows the exponential increase of Salvinia minima with respect to
time in weeks. This shows experiment one which held a starting culture of 24
individuals with no nutrient variable.
[Type text]
Galanti, 6
[Type text]
Figure 2: Scatterplot of experiment 2; Salvinia with excess nitrogen in N vs t
Experiment 2: Salvinia w/ Nitrogen
400
350
300
250
Experiment 2: Salvinia w/
Nitrogen
200
150
100
50
0
0
1
2
3
4
5
Figure two exhibits the exponential increase of Salvinia minima with respect
to time in weeks. This shows experiment two with a starting culture of 24
individuals and an increased nitrogen level.
Figure 3: Ln(N) vs. t
Experiment 2: Ln(N) vs. t
7
6
5
Experiment 2: Ln(N) vs. t
4
3
Linear (Experiment 2:
Ln(N) vs. t)
2
1
0
0
1
2
3
4
5
Figure 3 represents the natural log of N, number of individuals, against time
in weeks.
Figure 4: Lambda vs. N
[Type text]
Galanti, 7
[Type text]
lambda vs. N
3.5
3
2.5
2
lambda vs. N
1.5
y = -0.0231x + 6.6299
Linear (lambda vs. N)
1
0.5
0
0
50
100
150
200
250
Among these calculations are the carrying capacity estimations by surface
area and by solving the equation of lambda vs. N.Figure one displays the collected
data of the control dish, 24 individuals of Salvinia minima in artificial pond water,
against t, time in weeks. This provides a baseline for the following experiment.
Following this is the table showing growth with added nitrogen. With the higher
results in this table it is clear that the water with a higher nitrogen level resulted in
a higher growth rate and carrying capacity than the control. The last two graphs
help to determine the growth rate with lambda and rmax calculations.
Discussion
The above data proves the hypothesis of an increased growth rate and
carrying capacity as a result of a higher level of available nitrogen in the water. In a
real world application this would correlate to higher numbers of Salvinia minima
individuals in polluted bodies of water. With a higher concentration of plant
individuals the nutrient uptake would be greater and bioremediation of the
[Type text]
[Type text]
Galanti, 8
waterway would be achieved quicker. The actual carrying capacity is thought to be
more than predicted by the surface area estimation. This can be accounted to thalli
not being level and having degrees of translucency allowing more individuals to
propagate. Although this experiment did not quantify the nutrient uptake of Salvinia
minima, due to an increased fitness of the species it is expected to uptake the
nutrient. Future experimentation should include the water to be monitored for
nutrient as time passes and graphs to be constructed showing the correlation of
water nutrient concentration vs. time. If both species are allowed to reach carrying
capacity in this future experiment ecologists will have a better understanding of
which plant to use in the bioremediation setting whether the target is phosphorus
or nitrogen.
This experiment is repeatable but varying results should be expected due to
error. This experiment was done in March of 2014 at a temperature-controlled
greenhouse at the Pennsylvania State University. With varying light intensities at
this season and variable weather patterns for this particular year repetitions of this
experiment are expected to vary. In addition to weather, pests were found in the
dishes, which may have been either competing, algae, or preying upon, fruit flies.
Both of these factors would limit the growth rate of the plant and the algae could
lower the carrying capacity of Salvinia minima. This may be done by a reduction in
sunlight, use of resources, or as a media to harbor diseases, which the fruit flies
could introduce into the population.
In conglomeration with the other scientists who conducted the relatable
experiments it was found that the nutrient phosphorus also increased both the
[Type text]
[Type text]
Galanti, 9
carrying capacity and growth rate for both species. As for the competition
experiment, Salvinia minima was shown to outcompete Leman minor in the given
time period.
References
1Hass,
C.A., D. Burpee, R. Meisel, and A. Ward. 2013. A Preliminary Study of the
Effects of Excess Nutrients and Interspecies Competition on Population Growth of
Lemna minor and Salvinia minima In A Laboratory Manual for Biology 220W:
Populations and Communities. (Burpee, D. and C. Hass, eds.) Department of Biology,
The Pennsylvania State University, University Park, PA.
2Beiswenger,
J. M. 1993. Experiments To Teach Ecology. A Project of the Education
Committee of the Ecological Society of America. Ecological Society of America,
Tempe, AZ. pp. 83-105.
3Dhir,
Bhupinder, 2009. Salvinia: an Aquatic Fern with Potential Use in
Phytoremediation. Department of Genetics, University of Delhi South Campus, New
Delhi 110021, India. Environ. We Int. J. Sci. Tech. 4 (2009) 23-27
4Núñez-López
RA, Meas Y, Gama SC, Borges RO, Olguín EJ. 2008. Leaching of lead by
ammonium salts and EDTA from Salvinia minima biomass produced during aquatic
phytoremediation. 154(1-3):623-32. Epub 2007 Nov 4