Physiological and molecular responses of coccolithophores to ocean acidification

• Main Author: Rachel Ellen Diner
• Other Authors: Jonathon Stillman, Edward Carpenter, Richard Dudgale
• Format: Master Thesis
• Language: English
• Published: San Francisco State University 2014
• Subjects: Ocean acidification
• Online Access: http://hdl.handle.net/10211.3/132001

The absorption of atmospheric pCO2 by the ocean causes changes in water chemistry, collectively termed ocean acidification (OA). Anthropogenic CO2 emissions have increased rapidly since the dawn of the industrial age, and OA is occurring faster than ever before. Marine phytoplankton abundance and distribution respond to these global climate changes, with many species being either directly or indirectly affected. Coccolithophores are globally abundant phytoplankton that create calcium carbonate shells. Through both photosynthesis and calcification they play an important role in marine ecosystems, the global carbon cycle, and ocean-atmosphere CO2 exchange. For my master's thesis research, I investigated both physiological and molecular responses of coccolithophores to ocean acidification. I examined global transcription of Emiliania huxleyi (Strain CCMP371) after long-term exposure to increased temperature and pCO2 predicted for the future, finding that although calcification rate increased in future conditions, genes related to calcification were not differentially expressed. I also investigated responses of the biogeochemically important coccolithophore genus Calcidiscus to increasing pC02. While all strains examined were negatively impacted, one lightly calcified strain was more resilient than the other more heavily calcified strains. Investigating how these two globally important coccolithophore species respond to OA will help the scientific community better understand and predict the effects of climate change on marine ecosystems, and on marine and global carbon cycling.