Hoppe Hans-Georg, Gocke Klaus, Koppe Regine, Begler Christian
Section of Marine Ecology, Institute of Marine Science, Düsternbroker Weg 20, D-24105 Kiel, Germany.
Nature. 2002 Mar 14;416(6877):168-71. doi: 10.1038/416168a.
The oceanic carbon cycle is mainly determined by the combined activities of bacteria and phytoplankton, but the interdependence of climate, the carbon cycle and the microbes is not well understood. To elucidate this interdependence, we performed high-frequency sampling of sea water along a north-south transect of the Atlantic Ocean. Here we report that the interaction of bacteria and phytoplankton is closely related to the meridional profile of water temperature, a variable directly dependent on climate. Water temperature was positively correlated with the ratio of bacterial production to primary production, and, more strongly, with the ratio of bacterial carbon demand to primary production. In warm latitudes (25 degrees N to 30 degrees S), we observed alternating patches of predominantly heterotrophic and autotrophic community metabolism. The calculated regression lines (for data north and south of the Equator) between temperature and the ratio of bacterial production to primary production give a maximum value for this ratio of 40% in the oligotrophic equatorial regions. Taking into account a bacterial growth efficiency of 30%, the resulting area of net heterotrophy (where the bacterial carbon demand for growth plus respiration exceeds phytoplankton carbon fixation) expands from 8 degrees N (27 degrees C) to 20 degrees S (23 degrees C). This suggests an output of CO2 from parts of the ocean to the atmosphere.
海洋碳循环主要由细菌和浮游植物的联合活动决定，但气候、碳循环和微生物之间的相互依存关系尚未得到充分理解。为了阐明这种相互依存关系，我们沿着大西洋的南北断面进行了海水高频采样。在此我们报告，细菌和浮游植物的相互作用与水温的经向剖面密切相关，水温是一个直接依赖于气候的变量。水温与细菌生产与初级生产的比率呈正相关，更强烈地与细菌碳需求与初级生产的比率呈正相关。在温暖的纬度地区（北纬25度至南纬30度），我们观察到主要是异养和自养群落代谢的交替斑块。计算得出的（赤道以北和以南数据的）温度与细菌生产与初级生产比率之间的回归线显示，在贫营养的赤道地区，该比率的最大值为40%。考虑到细菌生长效率为30%，由此产生的净异养区域（即细菌生长加呼吸所需的碳需求超过浮游植物碳固定的区域）从北纬8度（27摄氏度）扩展到南纬20度（23摄氏度）。这表明海洋部分区域有二氧化碳排放到大气中。
