Species-Specific Variations in the Nutritional Quality of Southern Ocean Phytoplankton in Response to Elevated pCO2

Water

Cathryn Wynn-Edwards³  Rob King¹  Andrew Davidson³  Simon Wright³  Peter D. Nichols²  Simon Wotherspoon³  So Kawaguchi³ 

[1] Australian Antarctic Division, 203 Channel Hwy, Kingston Tas 7050, Australia; E-mail:;Antarctic Climate & Ecosystems Cooperative Research Centre, University of Tasmania, Private Bag 80, Hobart, Tasmania 7001, Australia; E-Mail:;Institute for Marine and Antarctic Studies, University of Tasmania, Private Bag 129, Hobart, Tasmania 7001, Australia; E-Mails:

关键词: Antarctic phytoplankton;    biochemical changes;    polyunsaturated fatty acids;    nutritional quality;    ocean acidification;   

DOI  :  10.3390/w6061840

来源: mdpi

【 摘 要 】

Increased seawater pCO₂ has the potential to alter phytoplankton biochemistry, which in turn may negatively affect the nutritional quality of phytoplankton as food for grazers. Our aim was to identify how Antarctic phytoplankton, Pyramimonas gelidicola, Phaeocystis antarctica, and Gymnodinium sp., respond to increased pCO₂. Cultures were maintained in a continuous culture setup to ensure stable CO₂ concentrations. Cells were subjected to a range of pCO₂ from ambient to 993 µatm. We measured phytoplankton response in terms of cell size, cellular carbohydrate content, and elemental, pigment and fatty acid composition and content. We observed few changes in phytoplankton biochemistry with increasing CO₂ concentration which were species-specific and predominantly included differences in the fatty acid composition. The C:N ratio was unaffected by CO₂ concentration in the three species, while carbohydrate content decreased in Pyramimonas gelidicola, but increased in Phaeocystis antarctica. We found a significant reduction in the content of nutritionally important polyunsaturated fatty acids in Pyramimonas gelidicola cultures under high CO₂ treatment, while cellular levels of the polyunsaturated fatty acid 20:5ω3, EPA, in Gymnodinium sp. increased. These changes in fatty acid profile could affect the nutritional quality of phytoplankton as food for grazers, however, further research is needed to identify the mechanisms for the observed species-specific changes and to improve our ability to extrapolate laboratory-based experiments on individual species to natural communities.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.