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Date Permissions Signed


Date of Award


Document Type

Masters Thesis

Degree Name

Master of Science (MS)



First Advisor

Donovan, Deborah Anne, 1964-

Second Advisor

Strom, Suzanne L., 1959-

Third Advisor

Sulkin, Stephen D.

Fourth Advisor

Love, Brooke


This study examined the effects of elevated CO2 on the microalga Emiliania huxleyi. Two strains were compared, a calcifying (CCMP 2668) and a non-calcifying (CCMP 374) strain. The CO2 levels used were 390 ppm, 760 ppm, and 1000 ppm. The effects of CO2 on growth rate, cell size, calcification, particulate dimethylsulfoniopropionate (DMSPp), and chlorophyll were examined. Under elevated CO2, cell size in both strains and DMSPp in the calcifying strain increased. Calcification decreased under elevated CO2. DMSPp in the non-calcifying strain and chlorophyll content in the calcifying strain had non-linear responses when exposed to elevated CO2. Growth rate in both strains and chlorophyll in the non-calcifying strain were not affected by CO2 level. The change in DMSPp may be increasing the volume of water inside the cells, therefore increasing the cells size. The change in DMSPp may be a stress response or a path for excess carbon waste. The change in chlorophyll in the calcifying strain may be a result of both an increase in light availability from decreased calcification and an increase in cell size. Both strains experienced physiological changes under elevated CO2 that have implications for the food web and biogeochemical cycling. Increased cell size influences the types of predators that have access to Emiliania huxleyi, which may affect whether nutrients are transported through the food web or sink to the deep ocean and may lead to ecosystem shifts. Reduced calcification may cause a decrease in carbon exported to the deep ocean. It may also increase predation on Emiliania huxleyi. A change in DMSPp may alter the sulfur cycle and decrease grazing on Emiliania huxleyi.





Western Washington University

OCLC Number


Subject – LCSH

Coccolithus huxleyi--Effect of water acidification on; Seawater--Carbon dioxide content; Carbon dioxide--Physiological effect; Ocean acidification; Carbon cycle (Biogeochemistry); Calcification




masters theses




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