The role of hydrodynamics in shaping the composition and architecture of epilithic biofilms in fluvial ecosystems.
The role of hydrodynamics in shaping the composition and architecture of epilithic biofilms in fluvial ecosystems.
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DOI：
10.1016/j.watres.2017.09.054
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发表时间：
2017-12
期刊：
影响因子：
12.8
通讯作者：
Ute Risse‐Buhl;Christine Anlanger;K. Kalla;T. Neu;C. Noss;A. Lorke;M. Weitere
中科院分区：
文献类型：
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作者：
Ute Risse‐Buhl;Christine Anlanger;K. Kalla;T. Neu;C. Noss;A. Lorke;M. Weitere
以前的实验室和现场实验强调了流体力学在形成生物膜组成和结构中的重要性。在环境因素的复杂相互作用下，在多大程度上可以在自然流动中发现对流体动力学的响应仍然是未知的。在这项研究中，我们研究了近河床湍流的湍流动能（TKE）的组成和结构的生物膜成熟的两个山区流不同的溶解营养盐浓度的影响。在这两个流，TKE显着解释7%和8%的生物膜组成和结构的变化，分别。然而，在营养丰富的流，TKE显着解释12%和3%的生物膜组成和结构的变化，分别影响更明显。而在较低的营养浓度季节性变化的因素，如化学计量的溶解养分（N/P比）和光更重要，并解释41%和6%的生物膜组成和结构的变化，分别。没有观察到特定的生物膜特征，如在实验环境中响应于均匀和单向流动而观察到的细长波纹和流光。微生物生物量和表面积覆盖的生物膜冠与TKE增加，而生物膜厚度和孔隙度不受影响或减少。这些结果表明，在自然流动，近床流速和湍流强度随时间和空间波动，生物膜变得更加紧凑。它们均匀地分布在矿物表面，形成一层密集的球状细胞膜，看起来像鹅卵石路面。生物膜的紧密生长似乎有利于抵抗流体动力学剪切力，以避免位移。因此，近河床湍流可以被认为是重要的因素，塑造自然流动下生长的生物膜的组成和架构。
Previous laboratory and on-site experiments have highlighted the importance of hydrodynamics in shaping biofilm composition and architecture. In how far responses to hydrodynamics can be found in natural flows under the complex interplay of environmental factors is still unknown. In this study we investigated the effect of near streambed turbulence in terms of turbulent kinetic energy (TKE) on the composition and architecture of biofilms matured in two mountainous streams differing in dissolved nutrient concentrations. Over both streams, TKE significantly explained 7% and 8% of the variability in biofilm composition and architecture, respectively. However, effects were more pronounced in the nutrient richer stream, where TKE significantly explained 12% and 3% of the variability in biofilm composition and architecture, respectively. While at lower nutrient concentrations seasonally varying factors such as stoichiometry of dissolved nutrients (N/P ratio) and light were more important and explained 41% and 6% of the variability in biofilm composition and architecture, respectively. Specific biofilm features such as elongated ripples and streamers, which were observed in response to the uniform and unidirectional flow in experimental settings, were not observed. Microbial biovolume and surface area covered by the biofilm canopy increased with TKE, while biofilm thickness and porosity where not affected or decreased. These findings indicate that under natural flows where near bed flow velocities and turbulence intensities fluctuate with time and space, biofilms became more compact. They spread uniformly on the mineral surface as a film of densely packed coccoid cells appearing like cobblestone pavement. The compact growth of biofilms seemed to be advantageous for resisting hydrodynamic shear forces in order to avoid displacement. Thus, near streambed turbulence can be considered as important factor shaping the composition and architecture of biofilms grown under natural flows.