Effect of elevated CO2 on the dynamics of particle-attached and free-living bacterioplankton communities in an Arctic fjord

• Published in: Biogeosciences 2013-01, Vol.10 (1), p.181-191
• Main Authors: Sperling, M, Piontek, J, Gerdts, G, Wichels, A, Schunck, H, Roy, A.-S, Roche, J La, Gilbert, J, Nissimov, J I, Bittner, L, Romac, S, Riebesell, U, Engel, A
• Format: Article
• Language: English
• Subjects: Environmental Sciences; Life Sciences
• ISSN: 1726-4170; 1726-4189
• DOI: 10.5194/bg-10-181-2013

In the frame of the European Project on Ocean Acidification (EPOCA), the response of an Arctic pelagic community (3 μm) and free-living (FL; < 3 μm > 0.2 μm) bacteria by Automated Ribosomal Intergenic Spacer Analysis (ARISA) in 6 of the mesocosms, ranging from 185 to 1050 μatm initial pCO2 , and the surrounding fjord. ARISA was able to resolve, on average, 27 bacterial band classes per sample and allowed for a detailed investigation of the explicit richness and diversity. Both, the PA and the FL bacterioplankton community exhibited a strong temporal development, which was driven mainly by temperature and phytoplankton development. In response to the breakdown of a picophytoplankton bloom, numbers of ARISA band classes in the PA community were reduced at low and medium CO2 (~ 185-685 μatm) by about 25%, while they were more or less stable at high CO2 (~ 820-1050 μatm). We hypothesise that enhanced viral lysis and enhanced availability of organic substrates at high CO2 resulted in a more diverse PA bacterial community in the post-bloom phase. Despite lower cell numbers and extracellular enzyme activities in the post-bloom phase, bacterial protein production was enhanced in high CO2 mesocosms, suggesting a positive effect of community richness on this function and on carbon cycling by bacteria.