Samuel Kim, Dr. Jillian Decker, Dr. Kristopher Baker The Effects of Ocean Acidification on Emiliania huxleyi and Thalassiosira pseudonana Samuel Kim, Dr. Jillian Decker, Dr. Kristopher Baker

Introduction The increasing usage of fossil fuels since the Industrial Revolution has led to an exponential increase in the concentration of greenhouse gases in the atmosphere. This has led to the well known problem of global warming. However, there is another problem caused by increasing emission of greenhouse gases that poses an equal or greater threat than global warming: Ocean acidification.

Introduction http://www.oceanacidification.org.uk/

Introduction This can be very harmful to many marine organisms, especially microorganisms like phytoplankton due to their sensitivity to environment conditions. Little is known on how phytoplankton react to the effects of ocean acidification, and different species may react differently. Therefore more research is needed.

Review of Literature (Riebesell et al., 1993; Rost et al., 2008) The rate of photosynthesis increases with the availability of carbon dioxide, benefitting phytoplankton. (Rost et al., 2008) Suggested that the increased availability of CO2 in the ocean could lead to increased growth rates in phytoplankton.

Review of Literature (Iglesias-Rodriguez et al., 2008) The coccolithophore Emiliania huxleyi in particular had contradicting results to the effects of ocean acidification. (Shi et al., 2012) Chemistry change in the ocean limits nutrient availability, negatively affecting phytoplankton.

Statement of Purpose The main goal of this study was to measure specific growth rates and doubling times in the diatom, T. pseudonana, and the coccolithophore, E. huxleyi. It was hypothesized that the growth rates of both species would decrease as pH decreased, with E. huxleyi having a much greater difference in growth rate due to the added burden of coccolith maintenance in lower carbonate.

Statement of Purpose A secondary goal of this study was to identify the relationship between light absorbance and cell density for both E. huxleyi and T. pseudonana to provide a more rapid method of measuring cell density. It was also hypothesized that there would be a positive relationship between cell density and absorbance due to the increasing amount of cells contributing to photosynthesis, and that finding cell density from absorbance would be possible.

Methodology

Results E. huxleyi Growth Averages

Results T. pseudonana Growth Averages

Results

Results

Discussion The results for E. huxleyi and T. pseudonana were both statistically insignificant. To verify the validity of our results, a similar experiment should be run that has a larger sample size and a larger time frame. Light absorbance can be used as a method to measure cell density. However, another experiment should be run with a larger time frame to see the validity in the relationship between light absorbance and cell density.

Discussion •Our results show that E. huxleyi will be able to adapt quickly to changes in the ecosystem while maintaining the similar growth rate to the control. •Our results conflict with those of Franklin et al., (2012), which showed a decreased growth rate for diatoms under the influence of ocean acidification.

Conclusion Coccolithophores start out with a negative reaction towards increased carbonate concentrations and lowered pH levels, but adapt quickly to match the control growth rate. Diatoms suffer a slight growth rate decrease, but quickly react to the increased carbonate concentrations and lowered pH levels to have a fast growth rate and doubling time. There is a positive correlation between light absorbance and cell density.

Acknowledgements I would like to thank my mentors Dr. Jillian Decker and Dr. Kristopher Baker for helping me with my project My parents for supporting me And my science research teachers: Ms. Foisy, Ms. Kleinman, and Ms. O’Hagan for their continued support throughout the program

Samuel Kim, Dr. Jillian Decker, Dr. Kristopher Baker The Effects of Ocean Acidification on Emiliania huxleyi and Thalassiosira pseudonana Samuel Kim, Dr. Jillian Decker, Dr. Kristopher Baker