Coupling of heterotrophic bacteria to phytoplankton bloom development at different pCO2 levels: a mesocosm study
Coupling of heterotrophic bacteria to phytoplankton bloom development at different pCO2 levels: a mesocosm study
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DOI：
10.5194/bg-5-1007-2008
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发表时间：
2008-01-01
期刊：
影响因子：
4.9
通讯作者：
Grossart, H. -P.
中科院分区：
文献类型：
--
作者：
Allgaier, M.;Riebesell, U.;Grossart, H. -P.
预计的人为二氧化碳排放量的增加将增加上层海洋的二氧化碳浓度并降低海水pH值。最近的研究揭示了pCO(2)引起的海水化学变化对多种海洋生物的影响，特别是钙化生物。为了检验预测的pCO(2)的增加是否会直接或间接（通过浮游植物动态变化）影响浮游植物华生长过程中异养细菌的丰度、活动和群落组成，我们用CO2曝气中生态系统，获得三种不同CO2分压（pCO(2)）的三倍：350亩atm（1倍CO2）、700亩atm（2倍CO2）和1050亩atm（3倍CO2）。浮游植物繁殖的发展是由硝酸盐和磷酸盐的添加引起的。随着pCO(2)的增加，游离菌和附着菌的细菌产量（BPP）以及附着菌的细胞特异性BPP （csBPP）与悬浮物的C:N比有关。这些关系在不同处理之间有显著差异。然而，细菌丰度和活性在不同处理之间没有统计学差异。单独的游离菌群落结构随pCO(2)的变化而变化，而附着菌的群落结构似乎与pCO(2)无关，但与浮游植物华生长密切相关。我们的研究结果表明，虽然pCO(2)的变化反映了自由生活细菌群落结构的变化，但并不直接影响细菌的活性。此外，异养细菌的细菌活性和动态，特别是附着细菌，与浮游植物的发育密切相关，因此也可能潜在地依赖于pCO的变化(2)。
The predicted rise in anthropogenic CO2 emissions will increase CO2 concentrations and decrease seawater pH in the upper ocean. Recent studies have revealed effects of pCO(2) induced changes in seawater chemistry on a variety of marine life forms, in particular calcifying organisms. To test whether the predicted increase in pCO(2) will directly or indirectly (via changes in phytoplankton dynamics) affect abundance, activities, and community composition of heterotrophic bacteria during phytoplankton bloom development, we have aerated mesocosms with CO2 to obtain triplicates with three different partial pressures of CO2 (pCO(2)): 350 mu atm (1 x CO2), 700 mu atm (2 x CO2) and 1050 mu atm (3 x CO2). The development of a phytoplankton bloom was initiated by the addition of nitrate and phosphate. In accordance to an elevated carbon to nitrogen drawdown at increasing pCO(2), bacterial production (BPP) of free-living and attached bacteria as well as cellspecific BPP (csBPP) of attached bacteria were related to the C:N ratio of suspended matter. These relationships significantly differed among treatments. However, bacterial abundance and activities were not statistically different among treatments. Solely community structure of free-living bacteria changed with pCO(2) whereas that of attached bacteria seemed to be independent of pCO(2) but tightly coupled to phytoplankton bloom development. Our findings imply that changes in pCO(2), although reflected by changes in community structure of free-living bacteria, do not directly affect bacterial activity. Furthermore, bacterial activity and dynamics of heterotrophic bacteria, especially of attached bacteria, were tightly correlated to phytoplankton development and, hence, may also potentially depend on changes in pCO(2).