Effect of Ocean Acidification on the Food Quality of the Coccolithophore Emiliania huxleyi

The anthropogenic burning of fossil fuels has doubled atmospheric carbon dioxide (CO₂) levels over the last 200 years. Atmospheric CO₂ diffuses into the ocean, changing the chemistry and decreasing the pH of seawater in a process called Ocean Acidification (OA). Calcifying marine phytoplankton, coccolithophores, are vulnerable to OA. Emiliania huxleyi is a lipid-dense and globally-abundant species of coccolithophore, therefore it is a vital food source for higher marine trophic levels. The objective of this project was to determine how OA affects the lipid profile and calcification of E. huxleyi CCMP #371. Gas chromatography was used to determine how the proportions of saturated (SFA), monounsaturated (MUFA), and polyunsaturated fatty acids (PUFA) in E. huxleyi varied with increasing pCO₂. Flow cytometry was used to measure how the distribution of highly calcified cells, partially calcified cells, and un-calcified cells changed with increasing pCO₂. The proportion of MUFA increased with pCO₂. The proportion of un-calcified and partially calcified cells increased with increasing pCO₂, however, the results varied across two experimental runs. In conclusion, the lipid-profile and calcification properties of E. huxleyi, and likely its food quality to predators, are affected by OA.