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Faculty Advisor

Kyle Grice, Jason Bystriansky

Abstract

Ocean acidification is a growing problem that may affect many marine organisms in the future. Within 100 years the pH of the ocean is predicted to decrease to 7.8, from the current ocean pH of around 8.1. Using phenolic acid levels as a stress indicator as well as respiration and chlorophyll content as a measure of health, the effect of lowering pH was tested on the seagrass, Cymodocea nodosa, in a controlled environment. Plant samples, water, and soil were taken from the Bay of Cádiz, Spain, and placed in aquaria in a temperature-controlled room. One control group was left untreated with a pH of approximately 8.1, while experimental groups maintained pH levels of 7.8 and 7.5. Using High Performance Liquid Chromatography (HPLC), concentration of the phenol rosmarinic acid was quantified in the plants. Average concentration for the control group was 1.7 μg g-1, while it was 2.9 μg g-1 for pH group 7.8, and 10.1g g-1 for pH group 7.5. To evaluate the overall health of C. nodosa within the three groups, chlorophyll concentration and photosynthesis/respiration rates were determined. A one-tailed ANOVA test was conducted using the chlorophyll concentrations of the three groups. With an F-value of 1.360 and a p-value of 0.287, the differences between the groups were not statistically significant. Although the raw data shows a slight decrease in chlorophyll content between the control group and the pH group 7.5, these discrepancies might have been larger or smaller due to sampling or experimental error. Additionally, the average values with their respective standard deviations were calculated for the respiration rates and oxygen production of each group. A one-tailed ANOVA was also used to determine the relationship between rosmarinic acid content and pH levels between the groups, with an F-value of 5.1423 and a p-value of 0.050.

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