Distinct patterns of microbial metabolism associated to riverine dissolved organic carbon of different source and quality
Distinct patterns of microbial metabolism associated to riverine dissolved organic carbon of different source and quality
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DOI：
10.1002/2015jg002963
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发表时间：
2015-06-01
影响因子：
3.7
通讯作者：
del Giorgio, Paul A.
中科院分区：
文献类型：
--
作者：
Berggren, Martin;del Giorgio, Paul A.
河流中的溶解有机碳（DOC）含有多种可被微生物吸收的分子。然而，对于DOC的来源和组成如何调节DOC支持微生物生长和呼吸的程度，目前还没有全面的了解。我们通过结合短期细菌产生和呼吸测量与长期DOC损失以及细菌使用不同单一基质的分析，分析了魁北克不同溪流和河流中DOC的微生物代谢模式。我们发现不同的代谢模式确实存在于不同的集水区，反映了DOC的不同性质和来源。例如，森林源头的DOC系统地支持最高的细菌生长效率（BGE），而泥炭沼泽排水的DOC则显著降低了BGE。清澈的山地河流中的碳消耗（可能以原生藻类DOC为代表）支持最高的细菌呼吸速率和最高的长期DOC损失。通过主成分分析，我们证明了所有测量的代谢反应的主要变化轴与荧光分光光度法测定的DOC组成指标和DOC来源的同位素指标密切相关。如果假设因果关系，我们的研究结果表明，不同来源的DOC供应的变化，例如由土地利用或气候变化引起的变化，应该导致水生微生物代谢模式的剧烈变化，从而改变水生生态系统功能，可能对食物网结构和温室气体平衡产生影响。
Dissolved organic carbon (DOC) in rivers contains a wide range of molecules that can be assimilated by microbes. However, there is today no integrated understanding of how the source and composition of this DOC regulate the extent to which the DOC can support microbial growth and respiration. We analyzed patterns in microbial metabolism of DOC from different streams and rivers in Quebec, by combining short-term bacterial production and respiration measurements with long-term DOC loss and analyses of bacterial use of different single substrates. We show that distinct metabolic patterns indeed exist across catchments, reflecting the varying nature and sources of the DOC. For example, DOC from forest headwaters systematically supported the highest bacterial growth efficiency (BGE) that was recorded, while in contrast DOC in peat bog drainage was used with significantly lower BGE. The carbon consumption in clear mountain rivers, possibly represented by autochthonous algal DOC, supported the highest bacterial respiration rates and the highest long-term DOC losses. By using principle component analysis, we demonstrate how the major axes of variation in all of the measured metabolic responses are tightly connected to spectrofluorometrical DOC composition indicators and to isotopic indicators of DOC source. If causality is assumed, our results imply that changes in DOC supply from different sources, for example, caused by land use or climate change, should result in dramatic changes in the patterns of aquatic microbial metabolism and thus in altered aquatic ecosystem functioning, with likely consequences for food-web structures and greenhouse gas balances.