Effect of CO2 enrichment on bacterial production and respiration and on bacterial carbon metabolism in Arctic waters

The impact of rising carbon dioxide (pCO2) on bacterial production (BP), bacterial respiration (BR) and bacterial carbon metabolism was investigated during the mesocosm experiment in Kongsfjord (Svalbard) in 2010. The mesocosm experiment lasted 30 days and nine mesocosms with pCO2 levels ranging from ca. 180 to 1400 μatm were used. Generally, BP gradually decreased in all mesocosms in an initial phase, showed a large (3.6-fold in average) but temporary increase on day 10, and increased slightly afterwards. BP increased with increasing pCO2 at the beginning of the experiment (day 5). This trend became inversed and BP decreased with increasing pCO2 on day 14 (after nutrient addition). Interestingly, increasing pCO2 enhanced the leucine and thymidine ratio at the end of experiment, suggesting that pCO2 may alter the growth balance of bacteria. In contrast to BP, no clear trend and effect of changes of pCO2 was observed for BR, bacterial carbon demand and bacterial growth efficiency. Our results suggest that (1) the response to elevated pCO2 had a strong temporal variation, potentially linked to the nutrient status, and (2) pCO2 had an influence on biomass accumulation (i.e. BP) rather than on the conversion of dissolved organic matter into CO2 (i.e. BR).

Motegi C., Tanaka T., Piontek J., Brussaard C. P. D., Gattuso J.-P. & Weinbauer M. G., 2012. Effect of CO2 enrichment on bacterial production and respiration and on bacterial carbon metabolism in Arctic waters. Biogeosciences Discussions 9: 15213-15235. Article.


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