The Effect of Phosphate on Biofilm Algal Numbers

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The Effect of Phosphate on Biofilm Algal
Numbers By Riley Lehman, Ryan Martin, Adriana
McMullan, Shelly Meyer, Jacob Phillips Josiah
Polito
Abstract After hypothesizing that doubling the
phosphate concentration will double the algae
numbers, we filled two containers full of water
from the Avenue of the Saints pond. For four
weeks we sampled the microcosms, centrifuged, and
then counted the algae. We also doubled the
amount of phosphate in the experimental container
each week.
Introduction Phosphate is a very important
nutrient that limits the productivity of many
algae in freshwater and marine environments. In
fact, it is important to have a large supply of
phosphorus because the phytoplanktons, kinds of
algae, form the base of the food web. These
species are responsible for half the
photosynthesis on earth, they remove almost as
much carbon dioxide from the atmosphere as all
land plants, and supply half the oxygen we
breathe. We tested our microcosm to see if the
added concentration of phosphate was helping the
algae grow.
Materials and Methods Our microcosms consisted of
two seventeen liter plastic containers each
filled with 15 L of water taken from the samples
of water in the 45-gallon garbage cans using a
one liter graduated cylinder. One container was
labeled Experimental and the other Control.
The two containers were stored in the Biology
labs greenhouse. After placing the two
containers in the greenhouse, eight tiles were
first cleaned and then four were placed into each
container, one along each side of the container.
We used the HACH DR/700 Calorimeter with PhosVer
3 Phosphate Reagent Powder Pillow for a 10 mL
sample to determine the level of phosphate in the
experimental container. The stock solution of
phosphate used in the microcosms was NaPO4.
Along with testing the phosphate level in the
microcosms, we also tested the pH level and the
conductivity. The HACH sensION5 conductivity
tester was used to calculate the conductivity by
placing it in the two containers and waiting for
the display to stabilize and show a number.
After calculating the levels of phosphate, pH,
and conductivity, samples from each microcosm
were taken and viewed using microscopes. Before
adding new levels of phosphate to the
experimental microcosm, a tile from each
microcosm was removed in order to obtain samples
to view. Ten different fields were viewed and the
number of each organism was counted.
Results From our results, the group derived the
general idea that the algae increased with the
phosphate level because the algae thrived on the
higher phosphate levels. Over the period of five
weeks we increased the level of phosphate from
0.03 mg/L the first week to 2.09 mg/L the last
week. Specific types of algae increased to
different levels while other specific types of
algae decreased. We have shown below the results
of our control and experimental environments. We
could not show all of the figures, but we put in
the first sample, the middle sample, and the
final sample.
Discussion/Conclusion Our findings proved our
hypothesis that doubling the phosphate
concentration will double the algae numbers. We
experienced an increase in the total amount of
algae found in the experimental environment. Not
all of the specialized types of algae increased
in number, but that was made up for by the
excessive increase found in the other types of
algae. Our experiment is very important because
high/low levels of phosphate concentration can
either hinder or benefit an ecosystem. Elevated
levels of phosphate are some of the causes for
trouble in the river runoff from fertilizers.
Paddy fields and golf courses are a source of
contamination after rainfall washes away the
fertilizer. People need to know this because it
greatly affects the ecosystem. Our experiment
helps to discover the rate at which the algae
increases and the types of algae that do or do
not increase in number. Researchers need to
study the water quality so people and other
organisms do not get hurt. Water quality and
periphyton structure differs significantly
between sites upstream and downstream of the
discharge. Typha latifolia, a type of periphyton,
is a useful indicator of the impact of waste
waters on the biota and can also be used to
evaluate water body recovery. This is a type of
algae that might be useful to study if we were to
do our experiment again. Our experiment can
benefit other people and the environment by
helping future studies.