Effects of elevated pCO2 on Emiliania huxleyi genetic diversity and the viruses that infect E. huxleyi (EhVs) have been investigated in large volume enclosures in a Norwegian fjord. Triplicate enclosures were bubbled with air enriched with CO2 to 760 ppmv whilst the other three enclosures were bubbled with air at ambient pCO2; phytoplankton growth was initiated by the addition of nitrate and phosphate. E. huxleyi was the dominant coccolithophore in all enclosures, but no difference in genetic diversity, based on DGGE analysis using primers specific to the calcium binding protein gene (gpa) were detected in any of the treatments. Chlorophyll concentrations and primary production were lower in the three elevated pCO2 treatments than in the ambient treatments. However, although coccolithophores numbers were reduced in two of the high-pCO2 treatments; in the third, there was no suppression of coccolithophores numbers, which were very similar to the three ambient treatments. In contrast, there was considerable variation in genetic diversity in the EhVs, as determined by analysis of the major capsid protein (mcp) gene. EhV diversity was much lower in the high-pCO2 treatment enclosure that did not show inhibition of E. huxleyi growth. Since virus infection is generally implicated as a major factor in terminating phytoplankton blooms, it is suggested that no study of the effect of ocean acidification in phytoplankton can be complete if it does not include an assessment of viruses.
Bibliographical noteFunding Information:
Twenty-seven people participated in the mesocosm experiment and we thank all of them for their contributions. In particular, we thank Dorothee Bakker for high precision measurements of the carbonate system, Isabel Mary and Andrew Whiteley for flow cytometer measurements of coccolithophore number and Cecilia Balestreri for laboratory support. Special thanks are due to the staff at the Espegrand field station for their assistance. The mesocosm experiment was supported by NERC, through Grant No. NE/C507902, as part of the Post-Genomics and Proteomics Programme.
© 2017 by the authors. Licensee MDPI, Basel, Switzerland.
- Climate change
- Emiliania huxleyi
- Ocean acidification