Amanda Behmer - Graphical Data Analysis

Graph #1: Average turbidity as a function of C.reinhardtii growth over three days in 8 different experimental cultures containing approximately 0.1g of unwashed PET powder (A-D) or approx. 0.1g washed PET powder (Q-Z) irradiated for varying lengths of time in comparison to a positive control group (R).

Graph #2: Average Resistance (with standard deviation of three biological replicates) as a function of C.reinhardtii optical culture density from 9 different culture groups at 2.2% inoculation- each containing filtered leachate solutions of either washed (A-D) or unwashed (Q-Z) PET microplastics irradiated for varying amounts of time and a control group (R) containing no PET microplastic leachate- over a time period of 76 hours.

Analysis of Graph #1

Plastics were UV irradiated prior to exposure to cultures in order to introduce potential variation in culture growth inhibition based on plastic weathering. However, there was not a statistically significant difference in culture density based on UV irradiation. Experimental groups experienced between a 1.28NTU to 2-fold increase in turbidity over the time period, while the control group (R ) experienced a 49.73NTU fold increase in turbidity- at least 47.7 more NTU than experimental groups. Because of this, there was a statistically significant difference in culture density based on the presence of plastics.

Analysis of Graph #2

Cultures did not experience a statistically significant difference in culture density based on varying UV-irradiation-generated plastic leachates. However, these results could likely be attributed to experimental error. Under a microscope, our mentor found lysed C. reinhardtii cells; these likely impacted density measurements and impacted the quality of the algal growth environment. Additionally, interspecific competition is a likely inhibitory factor in the growth of algae cultures, as we had grown the cultures for two weeks prior to the experiment. Thus, the algae were reaching a high density and were also near the end of their life cycle.