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Algal Culture Study
1 INTRODUCTION
1.1PURPOSE
Small scale freshwater toxicity investigations must be
done on a regular basis in order to ensure a healthy
habitat is available for the organisms present. Testing
for possible toxins is vital in investigations, as well
as examining for an extended period of time, the
organisms living within the ecosystem. In doing so, a
general idea of behavioral characteristics will be
recorded and observed; this will allow for a contrast
in behavior, if a toxin happens to be exposed to the
freshwater.
1.2ALGAL SPECIES
The species of algae that was used for this study was
Selenastrum algae that was cultured and stored in the
toxicology lab under 24hour light illumination.
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1.3CULTURE TECHNICIAN
The culture technicians who performed this study were
Brett Larabie and Jason Straun.
1.4CULTURE MEDIUM
The algae was cultured and used throughout the semester
for various activities, and could be found under the 24
hour lit bench in the toxicology lab.
1.5LIGHT INTENSITY (LUX)
1000
1.6DATE INITIATED
The initial start date for this study was January 7th,
2015.
1.7DATE HARVESTED
The date that the algae was harvested for the
algistatic assay was April 1st, 2015.
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2 DATA
2.1ABSORBANCE
The algae was not diluted at all, due to the fact that
the absorbance of the algal culture was 0.718; if the
450nm absorbance is above 1, then the sample must be
diluted to a 0-1 reading.
2.2SLOPE VALUE FROM BEER’S LAW PLOT (ML./CELLS)
The slope value from the “Beers Law Plot” in the
Examination of Algae and the Determination of K is 6 x
10-8.
3 RESULTS
3.1 TABLE 1
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3.4 FIGURE 1.1
3.2 [CU]
{MG/
L}
3.3 TUBE # CELL DENSITY (CELLS/ML) AVG
(F/I)
FOR 2
TUBES
LOG OF AVG
(F/I)
INITIAL FINAL RATIO OF
F/I
0 1:0.182
2:0.174
1.41 X
107
1: 3.03
X 10-10
2: 2.8
x 10-10
1: 0.0021
2: 0.0020
0.00205 -2.688
0.5 1:0.184
2: 0.164
1.41 X
107
1: 3.06
X 10-10
2: 2.73
x 10-10
1: 0.0022
2: 0.0019
0.00205 -2.688
1.0 1: 0.141 1.41 X
107
1: 2.35
X 10-10
1: 0.0016
2: 0.0019
0.00175 -2.757
y = -0.0361x - 2.7127
R² = 0.4078
-2.77
-2.76
-2.75
-2.74
-2.73
-2.72
-2.71
-2.7
-2.69
-2.68
-0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2
log(finaldensity/initialdensity)
log[Toxicant]
Toxicant VS F/I
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2: 0.160
2: 2.67
x 10-10
3.0 1:0.165
2: 0.161
1.41 X
107
1: 2.75
X 10-10
2: 2.68
x 10-10
1: 0.0020
2: 0.0019
0.00195 -2.710
5.0 1: 0.160
2:0.146
1.41 X
107
1: 2.67
X 10-10
2: 2.43
x 10-10
1:0.0019
2: 0.0017
0.0018 -2.745
10.0 1: 0.143
2: 0.139
1.41 X
107
1: 2.83
X 10-10
2: 2.31
x 10-10
1: 0.0020
2: 0.0016
0.0018 -2.745
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Figure 1.1: Visual representation contrasting log of
toxicant (copper) and log (F/I). Where x=0, an adverse
test result occurred, resulting in an inconclusive
summary of the data.
4 DISCUSSION
4.1 DEFINE ALGISTATIC CONCENTRATION OF A TOXICANT
In my opinion, the algistatic concentration of a
toxicant is the ability of a toxicant to inhibit algae
growth. Algi meaning algae, and static meaning lacking
in change/movement. This phrase, if you will, just
means what quantity or concentration of toxicant will
it take to inhibit the growth of the actual algae.
4.2 HOW OFTEN WERE THE TUBES SHOOK
The test tubes were shook every day of the test to keep
the salutation homogenized, as the algae had the
tendency to settle at the bottom of the tube if left
for an extended period of time. In order to record
accurate test results, the solutions needed to be
homogenized daily.
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4.3 CALCULATION FOR FINAL CELL DENSITY (SECOND TUBE)
Since the original solutions of algae were of a <1
absorbance, a “corrected absorbance” was never actually
created and therefore the formula was altered to better
suit the specific results;
Cell Density= absorbance/slope
0.146/6 x 10-8
2.43 x 10-10
4.4 TOXICANT RELEASED INTO LAKE IN HIGH QUANTITY
If a toxicant is released into a waterbody this has
potential to cause adverse effects on the entire
ecosystem. This could result in a fish population
shift, algal blooms, etc. Organisms live in lakes
because they are accustomed to the parameters. If a
cold-water fish was put into a warm-water lake, it
would not survive. This is also true for algae and
other organisms living in the water body. When physical
parameters are change too drastically, organisms cannot
properly adapt and this will affect the entire food
chain. Copper specifically has the ability to compete
for binding sites of enzymes such urease, acid
phosphatase and ATPase, and can inhibit other enzymes
of nitrogen metabolism and photosynthesis. Small
amounts of metals are essential for biological
activities, however they can be toxic.
5 CONCLUSION
In conclusion, although our test results were
inconclusive and variable, it is clear that toxicants
such as copper have the ability to inhibit the growth
of algae in ecosystems. In the future, I would have
taken better care in checking parameters, to therefore
be more confident in the results.
