Coexistence of algae and bacteria: a test of the carbon hypothesis
Coexistence of algae and bacteria: a test of the carbon hypothesis
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藻类和细菌的共存：碳假说的检验
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
M. Loreau
中科院分区：
文献类型：
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作者：
T. Daufresne;Gérard Lacroix;D. Benhaim;M. Loreau
藻类和水生细菌对无机营养盐的竞争限制了这两种基本群体在水体中的共存。基于竞争和化学计量理论，碳假说指出，由于细菌是营养物质的更好竞争者，它们可能会驱使自己限制碳（C），因此营养限制藻类和C限制细菌之间自然会出现共存。我们测试了碳假说在24个封闭的水生微宇宙与4种不同的人工媒体接种的一个藻类（栅藻）和天然细菌群落。我们监测了藻类和细菌的生长，随着时间的推移共存，以及S。细菌和细菌群落。在所有24个微宇宙中，藻类和细菌群落都显示出净增长阶段，随后是平台期，反映了随时间的推移稳定共存。在高原，藻类的限制由氮（N）和/或磷（P），取决于介质，而细菌的共同限制由有机碳和营养物质N和P。我们认为，这些结果是一致的碳假说，我们讨论的事实，细菌的共同限制，而不是纯粹的C-有限的资源比理论。我们的研究结果提供的证据表明，即使在没有阻止竞争性排斥的因素（如空间异质性，时间波动，捕食者），浮游植物和细菌可以共存，并维持基本的生态系统功能，即初级生产和营养循环。
The competition between algae and aquatic bacteria for inorganic nutrients puts some constraints on the coexistence of these 2 essential groups in the water column. Based on competition and stoichiometry theories the carbon hypothesis states that, since bacteria are better competitors for nutrients, they may drive themselves to carbon (C)-limitation, so coexistence would naturally arise between nutrient-limited algae and C-limited bacteria. We tested the carbon hypothesis in 24 closed aquatic microcosms with 4 different artificial media inoculated with an alga (Scenedesmus obliquus) and a natural bacterial community. We monitored algal and bacterial growth, coexistence over time, and the limitation status of S. obliquus and the bacterial community. In all 24 microcosms, both the algal and the bacterial communities showed a net growth phase followed by a plateau, reflecting sta- ble coexistence over time. At the plateau, the algae were limited by nitrogen (N) and/or phosphorus (P), depending on the medium, whereas the bacteria were co-limited by organic C and the nutrients N and P. We argue that these results are consistent with the carbon hypothesis, and we discuss the fact that bacteria were co-limited instead of purely C-limited in light of the resource-ratio theory. Our results provide evidence that, even in the absence of factors preventing competitive exclusion (e.g. spatial heterogeneity, temporal fluctuations, predators), phytoplankton and bacteria can coexist and sustain basic ecosystem functions, namely primary production and nutrient cycling.