Response of bacterioplankton community structure to an artificial gradient of pCO2 in the Arctic Ocean
1State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China
2Division of Life Science and Division of Environment, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
3Microbial Ecology and Biogeochemistry Group, Université Pierre et Marie Curie-Paris 6, CNRS, Laboratoire d'Océanographie de Villefranche, 06230 Villefranche-sur-Mer, France
*These authors contributed equally to this work.
Abstract. The influences of ocean acidification on bacterial diversity were investigated using DNA fingerprinting and clone library analysis of bacterioplankton samples collected from the largest CO2 manipulation mesocosm study that had been performed thus far. Terminal restriction fragment length polymorphism analysis of the PCR amplicons of the 16S rRNA genes revealed that bacterial diversity, species richness and community structure varied with the time of incubation but not the degree of ocean acidification. The phylogenetic composition of the major bacterial assemblage after a 30-day incubation under various pCO2 concentrations did not show clear effects of pCO2 levels. However, the maximum apparent diversity and species richness which occurred during incubation differed in the high and low pCO2 treatments, in which different bacterial community structure harbored. In addition, total alkalinity was one of the contributing factors for the temporal variations in bacterial community structure observed during incubation. A negative relationship between the relative abundance of Bacteroidetes and pCO2 levels was observed for samples at the end of the experiment. Our study suggested that ocean acidification affected the development of bacterial assemblages and potentially impacts the ecological function of the bacterioplankton in the marine ecosystem.