algal culture study

Samantha Hornell

Environmental Toxicology

Brett LarabieAlgal Culture Report

1

Algal Culture Report

Algal Culture Study

1 INTRODUCTION

1.1 PURPOSE

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.

1.2 ALGAL 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.

2


1.3 CULTURE TECHNICIAN

The culture technicians who performed this study were Brett

Larabie and Jason Straun.

1.4 CULTURE 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.

1.5 LIGHT INTENSITY (LUX)

1000

1.6 DATE INITIATED

The initial start date for this study was January 7th, 2015.

1.7 DATE HARVESTED

The date that the algae was harvested for the algistatic assay was

April 1st, 2015.

3


2 DATA

2.1 ABSORBANCE

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.

2.2 SLOPE 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.

4


3 RESULTS

3.1 TABLE 1

5


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

2: 0.160

1.41 X 107 1: 2.35

X 10-10

1: 0.0016

2: 0.0019

0.00175 -2.757

6


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

7


3.4 FIGURE 1.1

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.

-0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2

-2.78

-2.76

-2.74

-2.72

-2.7

-2.68

-2.66

-2.64

f(x) = − 0.0360805504644015 x − 2.71270153559484R² = 0.40778521622187

Toxicant VS F/I

log [Toxicant]

log

(fina

l den

sity/

initi

al d

ensit

y)

8


4 DISCUSSION

4.1 DEFINE ALGISTATIC CONCENTRATION OF A TOXICANTIn 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 SHOOKThe 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.

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 QUANTITYIf 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

9


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.

algal culture study

Documents