University of Stuttgart, Institute for Modelling Hydraulic and Environmental Systems, Pfaffenwaldring 61, 70569 Stuttgart, Germany.
Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany.
Water Res. 2020 Oct 15;185:116182. doi: 10.1016/j.watres.2020.116182. Epub 2020 Jul 13.
Biofilm activities and their interactions with physical, chemical and biological processes are of great importance for a variety of ecosystem functions, impacting hydrogeomorphology, water quality and aquatic ecosystem health. Effective management of water bodies requires advancing our understanding of how flow influences biofilm-bound sediment and ecosystem processes and vice-versa. However, research on this triangle of flow-biofilm-sediment is still at its infancy. In this Review, we summarize the current state of the art and methodological approaches in the flow-biofilm-sediment research with an emphasis on biostabilization and fine sediment dynamics mainly in the benthic zone of lotic and lentic environments. Example studies of this three-way interaction across a range of spatial scales from cell (nm - µm) to patch scale (mm - dm) are highlighted in view of the urgent need for interdisciplinary approaches. As a contribution to the review, we combine a literature survey with results of a pilot experiment that was conducted in the framework of a joint workshop to explore the feasibility of asking interdisciplinary questions. Further, within this workshop various observation and measuring approaches were tested and the quality of the achieved results was evaluated individually and in combination. Accordingly, the paper concludes by highlighting the following research challenges to be considered within the forthcoming years in the triangle of flow-biofilm-sediment: i) Establish a collaborative work among hydraulic and sedimentation engineers as well as ecologists to study mutual goals with appropriate methods. Perform realistic experimental studies to test hypotheses on flow-biofilm-sediment interactions as well as structural and mechanical characteristics of the bed. ii) Consider spatially varying characteristics of flow at the sediment-water interface. Utilize combinations of microsensors and non-intrusive optical methods, such as particle image velocimetry and laser scanner to elucidate the mechanism behind biofilm growth as well as mass and momentum flux exchanges between biofilm and water. Use molecular approaches (DNA, pigments, staining, microscopy) for sophisticated community analyses. Link varying flow regimes to microbial communities (and processes) and fine sediment properties to explore the role of key microbial players and functions in enhancing sediment stability (biostabilization). iii) Link laboratory-scale observations to larger scales relevant for management of water bodies. Conduct field experiments to better understand the complex effects of variable flow and sediment regimes on biostabilization. Employ scalable and informative observation techniques (e.g., hyperspectral imaging, particle tracking) that can support predictions on the functional aspects, such as metabolic activity, bed stability, nutrient fluxes under variable regimes of flow-biofilm-sediment.
生物膜活动及其与物理、化学和生物过程的相互作用对各种生态系统功能至关重要，影响水-地貌、水质和水生生态系统健康。有效管理水体需要深入了解流动如何影响生物膜结合的沉积物和生态系统过程，反之亦然。然而，关于流动-生物膜-沉积物这一三角关系的研究仍处于起步阶段。在这篇综述中，我们总结了流动-生物膜-沉积物研究的当前现状和方法，重点介绍了生物稳定化和细颗粒动态，主要在流水和静水环境的底部区域。从细胞（纳米-微米）到斑块尺度（毫米-分米）的一系列空间尺度的这种三向相互作用的示例研究突出了跨学科方法的迫切需要。作为这篇综述的贡献，我们将文献综述与一项在联合研讨会框架内进行的试点实验的结果相结合，以探索提出跨学科问题的可行性。此外，在这次研讨会上，我们测试了各种观察和测量方法，并单独和组合评估了所获得结果的质量。因此，本文最后强调了在未来几年内，流动-生物膜-沉积物三角关系中需要考虑的以下研究挑战：i）建立水力和泥沙工程师以及生态学家之间的合作，以使用适当的方法研究共同的目标。进行现实的实验研究，以测试关于流动-生物膜-沉积物相互作用以及床层结构和机械特性的假设。ii）考虑水-沉积物界面处的空间变化的流动特征。利用微传感器和非侵入性光学方法的组合，如粒子图像 velocimetry 和激光扫描仪，以阐明生物膜生长的机制以及生物膜和水之间的质量和动量通量交换。使用分子方法（DNA、色素、染色、显微镜）进行复杂的群落分析。将不同的流动状态与微生物群落（和过程）联系起来，将细颗粒沉积物特性与增强沉积物稳定性（生物稳定化）的关键微生物功能联系起来。iii）将实验室规模的观察结果与更适合管理水体的大尺度联系起来。进行野外实验，以更好地了解可变流动和泥沙条件对生物稳定化的复杂影响。采用可扩展和信息丰富的观测技术（如高光谱成像、粒子跟踪），以支持对功能方面的预测，如代谢活性、床稳定性、在流动-生物膜-沉积物的变化条件下的养分通量。
