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

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

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

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

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

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.

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

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

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.

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: 0.00013

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: 0.00013 There appeared to be a significant positive effect on Chlamydomonas reinhardtii population growth when grown in after-rain creek water.

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

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.

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?)

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.

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, www.ecology.com/2011/09/02/the-most-important-organism-on-the-planet/. Perlman, USGS Howard. “Runoff (Surface Water Runoff).” Runoff (Surface Water Runoff), USGS Water Science School, 2 Dec. 2016, water.usgs.gov/edu/runoff.html.

ANOVA Day 6 Anova: Single Factor Day 6 SUMMARY Groups Count Sum Average Variance Control 8 1.573 0.191375 3.41E-06 Before Rain 1.531 0.196625 1.41E-06 After Rain 1.665 0.208125 1.7E-05 ANOVA Source of Variation SS df MS F P-value F crit Between Groups 0.001174 2 0.000587 80.78952 1.37E-10 3.4668 Within Groups 0.000153 21 7.27E-06 Total 0.001327 23  

ANOVA Day 14 Anova: Single Factor Day 14 SUMMARY Groups Count Sum Average Variance Control 8 1.619 0.202375 2.55E-06 Before Rain 1.721 0.215125 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 0.001587 2 0.000793 145.1776 5.06E-13 3.4668 Within Groups 0.000115 21 5.46E-06 Total 0.001701 23  

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 0.191375 1.41071E-06 Column 2 1.665 0.208125 1.69821E-05 ANOVA Source of Variation SS df MS F P-value F crit Between Groups 0.00112225 1 122.031068 2.6858E-08 4.600109937 Within Groups 0.00012875 14 9.19643E-06 Total 0.001251 15

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 0.215125 8.125E-06 Column 2 1.776 0.222 5.71429E-06 ANOVA Source of Variation SS df MS F P-value F crit Between Groups 0.000189063 1 27.32258065 0.000128085 4.600109937 Within Groups 9.6875E-05 14 6.91964E-06 Total 0.000285938 15