1. Effects of Rainfall on Aquatic Productivity
Jacob Cebulak
Pittsburgh Central Catholic HS
Grade 11

2. Runoff
Part of the water cycle and describes the water that flows over a land surface.
Surface runoff occurs on land, typically creating a ‘watershed.’
Artificial materials that are transported in surface runoff: fertilizers, petroleum, pesticides, herbicides, and salt.
Potential effects are assessed by chemical indicators and indicator species.
Rainfall can exacerbate this problem

3. Eutrophication Caused by an overabundance of nutrients in an ecosystem
No limiting factor on algae populations
Uncontrollable growth takes up resources necessary for other organisms-oxygen.
Limits biodiversity
Can occur naturally
Typically occurs today by fertilizer run off

4. Chlamydomonas reinhardtii
Used as a bio-indicator
Genus of green algae
Has an Eyespot to orient itself to light
Two flagella, swims with a breaststroke-like motion
10 μm in diameter
Large, crescent-shaped chloroplasts
Found in freshwater, soil, oceans, and snow

5. Purpose
To determine whether or not rainfall-induced runoff has a significant effect on algal population growth.

6. Hypotheses
Alternative: Runoff-laden creek water will significantly increase Chlamydomonas reinhardtii population growth.
Null: Runoff-laden creek water will have no significant effect on Chlamydomonas reinhardtii population growth.

7. Materials Chlamydomonas reinhardtii (Carolina) Tube rack Vortex
Plum Creek water prior to rainfall
Lamp (21cm from the tubes)
and after rainfall
12 watt light bulb
Spring Water
Wax Paper
Soil Water
Spectrophotometer
Micropipettes
13x100 borosilicate culture tubes

8. Procedure
1. Water was collected from Plum Creek before rainfall occurred.
2. Water was collected from Plum Creek 1 hour following heavy rainfall. (Note: The depth where the sample was collected rose by 2cm from when the first sample was collected.)
3. The tubes were then filled with the following concentrations. Each concentration had 8 replicates.
Control
Test Solution Before Rainfall
Test Solution After Rainfall
Creek Water Before Rainfall
0mL
4mL
Creek Water After Rainfall
Algae
1mL
Spring Water
2mL
Soil Water
Total Volume
5mL

9. Procedure (continued)
4. Tubes were inverted and the absorbances, at 430 nanometers, were recorded with a Carolina spectrophotometer. Spring water was used as a blank.
5. Placed tubes 21 cm below a 12 watt light bulb at 20 degrees Celsius.
6. Recorded absorbance of each tube every other day for 14 days.

10. Day 14 P-value comparing before and after rainfall:
Results
Day 14
P-Value:
5.06E-13
Day 14 P-value comparing before and after rainfall:

11. Was there significant variation between Chlamydomonas r
Was there significant variation between Chlamydomonas r. grown in before-rain creek water and after-rain creek water?
Alpha: 0.05
Day 6 p-value: 2.68E-08
Day 14 p-value:
There appeared to be a significant positive effect on Chlamydomonas reinhardtii population growth when grown in after-rain creek water.

12. Dunnett’s Tests T-Crit: 2.67 Alpha: 0.05
Test Solution Before Rainfall (Compared to the control)
Test Solution
After Rainfall
(Compared to the control)
Day 6
3.89
Significant
12.42
Day 14
10.97
16.89

13. Conclusions
Both samples of creek water seemed to promote Chlamydomonas growth.
The null hypothesis was rejected for both before and after rainfall due to the extremely low p-values. Increased rainfall seemed to significantly increase algal growth-promoting properties of creek water.

14. Limitations Only one model was tested.
The chemical composition of the creek was not tested nor was pH.
Absorbance variation of culture tubes.
There were only 8 replicates.
Only one water source was tested.
Overall growth was very low. (Optimal health?)

15. Extensions Use more than one model.
Use chemical indicators to determine the composition of the creek.
Test more than one water source.
Use more replicates.
Count the cells in the tubes for more precision.
Use different wattage bulbs.
Test different wavelengths of light.
Test optimal growth conditions.

16. References
Nenninger, Katie. “Chlamydomonas Reinhardtii.” Chlamydomonas Reinhardtii, Missouri Science and Technology, web.mst.edu/~microbio/BIO221_2009/C_reinhardtii.html. US Department of Commerce, National Oceanic and Atmospheric Administration. “NOAA's National Ocean Service Education: Estuaries.” NOAA's National Ocean Service, 19 Dec. 2004, oceanservice.noaa.gov/education/kits/estuaries/media/supp_estuar09b_eutro.html. “The Most Important Organism on the Planet.” Ecology Global Network, 27 Apr. 2012, Perlman, USGS Howard. “Runoff (Surface Water Runoff).” Runoff (Surface Water Runoff), USGS Water Science School, 2 Dec. 2016, water.usgs.gov/edu/runoff.html.

17. ANOVA Day 6 Anova: Single Factor Day 6 SUMMARY Groups Count Sum
Average
Variance
Control 8
1.573
3.41E-06
Before Rain
1.531
1.41E-06
After Rain
1.665
1.7E-05
ANOVA
Source of Variation SS df MS F
P-value
F crit
Between Groups 2
1.37E-10
3.4668
Within Groups 21
7.27E-06
Total 23

18. ANOVA Day 14 Anova: Single Factor Day 14 SUMMARY Groups Count Sum
Average
Variance
Control 8
1.619
2.55E-06
Before Rain
1.721
8.13E-06
After Rain
1.776
0.222
5.71E-06
ANOVA
Source of Variation SS df MS F
P-value
F crit
Between Groups 2
5.06E-13
3.4668
Within Groups 21
5.46E-06
Total 23

19. Day 6 ANOVA Before to After Rainfall
Anova: Single Factor
Day 6 Before to After Rainfall
SUMMARY
Groups
Count
Sum
Average
Variance
Column 1 8
1.531
E-06
Column 2
1.665
E-05
ANOVA
Source of Variation SS df MS F
P-value
F crit
Between Groups 1
2.6858E-08
Within Groups 14
E-06
Total 15

20. Day 14 ANOVA Before to After Rainfall
Anova: Single Factor
Day 14 Before and After Rainfall
SUMMARY
Groups
Count
Sum
Average
Variance
Column 1 8
1.721
8.125E-06
Column 2
1.776
0.222
E-06
ANOVA
Source of Variation SS df MS F
P-value
F crit
Between Groups 1
Within Groups
9.6875E-05 14
E-06
Total 15