James Anna K, Passow Uta, Brzezinski Mark A, Parsons Rachel J, Trapani Jennifer N, Carlson Craig A
Marine Science Institute, Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California, United States of America.
Bermuda Institute of Ocean Science (BIOS), St. George's, Bermuda.
PLoS One. 2017 Mar 3;12(3):e0173145. doi: 10.1371/journal.pone.0173145. eCollection 2017.
Factors that affect the removal of organic carbon by heterotrophic bacterioplankton can impact the rate and magnitude of organic carbon loss in the ocean through the conversion of a portion of consumed organic carbon to CO2. Through enhanced rates of consumption, surface bacterioplankton communities can also reduce the amount of dissolved organic carbon (DOC) available for export from the surface ocean. The present study investigated the direct effects of elevated pCO2 on bacterioplankton removal of several forms of DOC ranging from glucose to complex phytoplankton exudate and lysate, and naturally occurring DOC. Elevated pCO2 (1000-1500 ppm) enhanced both the rate and magnitude of organic carbon removal by bacterioplankton communities compared to low (pre-industrial and ambient) pCO2 (250 -~400 ppm). The increased removal was largely due to enhanced respiration, rather than enhanced production of bacterioplankton biomass. The results suggest that elevated pCO2 can increase DOC consumption and decrease bacterioplankton growth efficiency, ultimately decreasing the amount of DOC available for vertical export and increasing the production of CO2 in the surface ocean.
通过将一部分被消耗的有机碳转化为二氧化碳，影响异养浮游细菌去除有机碳的因素会对海洋中有机碳损失的速率和程度产生影响。通过提高消耗速率，表层浮游细菌群落还可以减少可供从表层海洋输出的溶解有机碳（DOC）的量。本研究调查了pCO2升高对浮游细菌去除从葡萄糖到复杂浮游植物渗出物和裂解物以及天然存在的DOC等几种形式DOC的直接影响。与低（工业化前和环境）pCO2（250-400 ppm）相比，升高的pCO2（1000-1500 ppm）提高了浮游细菌群落去除有机碳的速率和程度。去除增加主要是由于呼吸作用增强，而不是浮游细菌生物量生产增加。结果表明，pCO2升高会增加DOC消耗并降低浮游细菌生长效率，最终减少可供垂直输出的DOC量，并增加表层海洋中二氧化碳的产生。
